If you ever decide to give up your day job, you'd make a tremendous instructor. You take the time to research your subject matter before spouting off what you've found out. You also have a passion for the subject material. Let's face it, you've been part of several machine scraping classes and I'm sure that in those 5 days for each class, not everything is, or even can be, covered. I never tire of hearing you talk about these things. Keep it up! Hope your recovery continues to go well.
That's kind of what he did. He tried from teaching a&m and runs an educational website and RUclips channel. He occasionally works at the Georgia museum of agriculture doing machine work and such. I would guess he considers this kind of thing his day job though.
Yes, mechanical accuracy, flatness etc and temperature dependence is a rabbit hole one may never emerge from. Very good background and history lesson, thank you!
Nice find. I was recently in a shop of an older gentleman who builds and repairs some high-end race cars, and he had a cast-iron surface plate for inspecting for damage and alignment. He said it was 10 feet by 20 feet. The side rails under the perimeter of the top looked to be about three feet tall. I can only imagine how heavy this thing had to be.
If you dont need extreme accuracy, a piece of 3cm granite from your local granite countertop shop is great, pick the closest tightest grain structure you can find in the scrap 'black absolute' is one of the best but other colors work great. Ive use it for lapping and scraping parts in with no issues, ex exhaust manifolds, headder flanges, filter housing mating surfaces, carb bases, water outlets and such.
A friend of mine went to a company that made tombstones. He got one where they misspelled the name of the deceased, it was really cheap. He then lapped it in.
@@transmaster perfect scrap material for this purpose a mistake in a headstone cannot be fixed it must be replaced, theyd sell it to you for a song lol!
I'd be careful with glass plates, they are more flexible than you might think. Also the flatness isn't that great, I built a simple device for measuring flatness and tested a pane of glass, the indicator jumped all over the place even if it seemed to be flat. Anyway, I built a simple surface plate out of a broken granite tile (actually two, both halves were usable). The surface was somewhat ground already, but just to be sure I got some abrasive powder (silicon carbide) and lapped both plates onto eachother. The result turned out pretty good. It's not perfect, but I'd definitely trust it way more than a piece of glass.
Keith a very useful ready reckoner for Fahrenheit to Centigrade is that 61ºF = 16ºC and 82ºF = 28ºC and then just interpolate between the two sets of equivalents.
@@davidmam I think the conversion factor is actually 5/9 not 5/8. But therein lies the difficulty because it’s hard to remember! Otherwise I’d agree with you that the math isn’t too scary.
quick and dirty for C to F double the c and add 30 ,not completely accurate but near enough plus its a easy in the head one works the other way also - 30 / 2
Great information Keith, learned something new about the difference between those materials. Concerning the moving cart, use large wheeled castors that won't get hung up on small bits left on the floor. That thing has "top heavy" written all over it. Pretty sure you already thought of that but a reminder doesn't hurt.
My father was a Electrcal Engineer Inspector and his standard instruments were kept in the "Standards Room" never to leave at a constant temperature of 68F or 20C. Before he retired he took me on a visit to see all the amazing testing equipment they had. The most interesting for me was a 7KW lamp to imitate the sun and a Catapult Room with a sled on rails for acceleration measurements.
Nice find! I was a scraper hand at a machine tool rebuilding shop in Cleveland Ohio in the 70's. My shop had a beautiful 4'x8' scraped cast iron plate, the master of the shop full of many smaller surface plates, straightedges, and squares. It was treated as such, not used for storage, and always clean. I have also used granite, but find a scraped surface a little better for spotting, the transfer of the blue marking medium for the piece being scraped, that's just my opinion.
I love the machining videos you produce, but I'm never disappointed with a talky one. Your enthusiasm is infectious, your teaching style engaging and your subject matter always of interest. Nice purchase.
We have a cast iron one at the shop I work at. Its 4’x6’. Hasnt been lapped in years and hasnt been used as as surface plate for a long time. Mostly used as a workbench now. We have a few smaller granite surface plates for inspection use.
A great video Keith! So much information about the merits of cast iron versus granite surface plates. I've only room for a 12" x 12" granite in my tiny, tiny shop 7' X 5' yes that small in which I have a 12"x 19" lathe with a milling machine attachment. All the rest of my machinery is outside under cover lol. When I used to be a teacher we had a brand new 24"x 24" cast iron surface plate on a cast stand about 38" high and apart from myself on personal projects I only ever saw it used a couple of times by students. (My head of department taught the senior year examination students ) now it has probably been scrapped along with a 9" Viceroy Shaper, and a Tom Senior Horizontal mill that I was the only one to use. ( until I left of course) there were also 4 , 12"x and at least 24"lathes. One with a vertical milling attachment. Again I was the only one to use it in the 10 years I was there. All probably scrapped or just sold off. What a bloody waste!
"The Fundamentals Of Mechanical Accuracy", is simply one of the most fascinating technical books I have ever read. A must read for any machinist indeed just about anybody fullstop! Thanks for the great video
Hmm, I still have the sink plug that came out of our granite counter top and I’ve been thinking about what to do with it. Now I at least have an idea. Great video.
absolutely!! use it for typical shop needs those are really good surface plates for us hobby shop machinists/mechanics. Ive used one for years and it works great!
Great video Keith my dad was a Fitter at the same iron works as I served my time as a sparks . away I digress the fitting shop had the old fashioned oak block floor end grain up set on pitch ( nice for the legs and does not ding your tools ) the surface plate was some 20 foot by 12 foot and was constructed on a raised concrete slab, said to be six foot deep, the interesting thing was the cast iron top was made up of separate CI cubes about 1 * 1 * 1 foot , it was used to sett up for machining large casting for the items they assembled , the overhead crane had two blocks one 5 ton and the other 20 ton ( that's 2240 pounds ton ) , I never knew how good it was
Having a small home shop I cheat and use my cast iron table saw surface. I found this flatter than the granite "scrap". I have also used a wing of my 8" jointer for longer items. For the very few times, I have needed an accurate surface this has saved the day.
I picked up a 16" x 16" cast iron plate with a wooden cover from an auction. I wasn't planning on buying it, but no one was interested and got it for next to nothing. As i'm a novice engineer, I have yet to used it in anger, however there's been several times when it's been useful for lapping on emery (had been using glass). I doubt it's accurate, but well within the tolerances I will be doing. I'm really hoping Adam finds something similar and Keith would be willing to do a swap, to keep a tool that gramps might have used in the family.
I really enjoyed the historical context in this video. I also liked the way that you worked in the macro shots of the surface plate details and the pages of the book. It must take lots of time to edit those details into the video, but I feel that it really adds to the quality of the video. Thanks again for the great content!
Semi-related. We needed a 3x4 inspection surface for 120 pound ceramic objects to be sure the bottoms of the objects were flat within +/-0.06. Unglazed fired ceramic is extremely abrasive. I have purchased many surface plates both granite and, years ago, cast iron. Anything we used for a table would be highly abraded. So standard surface pates are not suitable. Granite surface plates would last only a few days. I searched for an old worn-out / damaged cast iron plate or machine base that could be repeatedly ground back to flat as it was worn from use. No such animal in the budget cost range. I resigned to building a cheap temporary table from steel. A local shop said they had a piece of WWII Sherman tank armor in their parking lot for years. They wanted it gone and at scrap steel prices. Could I use it for the inspection table if I altered some of the dimensions? Sure. I had the armor Blanchard ground both sides so it could be flipped over when one side wore out. Wow! After thousands of heavy parts dragged around on the table, the surface was still flat within +/- 0.0001 after 3 years. Did not have to flip it over and use the other ground surface. Absolutely amazing. I have seen cast iron and steel worn -0.01 after a few hundred heavy ceramic parts. Too bad the project is complete. Would like to keep that inspection table for the next future job.
Yeah no doubt. Armor plating is just that, armor. Hardened tool steel essentially. Ceramic will cut or abrade most anything. Even considering the plate was designed to stop ordnance, it's still impressive it stood up to 3 years of what amounts to the worst possible conditions outside of what it was made for. Pretty awesome.
I saw a 4x8 iron plate posted locally for scrap cost. I believe it was several tons and stood at bench height without legs. If I had room for it, I would own it for the simple fact they look cool. Until i have more room, my little bench top iron plate will do.
That book is an incredible source of information and is a fascinating read. Nice to see it being mentioned here. I enjoyed this video, thanks for producing it.
Loved this video. It was a walk down memory lane for me. During the 1970s I worked for a UK company that made cast iron surface plates. 10"x 8" through to 48" X 24". Yes cast iron is a very messy material to work with. I'm sorry to say the company has been gone for many years now.
I read "Machine Tool Reconditioning" by E.F. Connolly back in the eighties to check and correct all my machine tools. It's the best I ever read, probably similar to the one you show. When I got mine, I found a "carpet sample" at a flea market that was an exact fit for my 18 by 24 plate. I've had it for almost forty years, very handy to have for general machine work and for testing/try fit of precision fits. Before I found the granite, I had an apron from a large lathe, about three foot by one and a half, I scraped flat and true, used for ten or fifteen years.
Just ordered that book you referenced. Very expensive but right up my street. I remember my dad telling me that cast iron plates needed to be made in threes. My cast iron plate is only 12” by 12” and would have been purchased second hand in about 1950. When i get my precision ground stones i will certainly check for any high spots although the plate has a wooden cover which both my father and i have been careful to always used. Very interesting video!
Friend's dad owns a "Machinery Rebuilding" place...OK, so they USED to rebuild A LOT. They now do more reselling and sourcing than anything. He has two MASSIVE surface plates, one is Cast Iron and it HAS to be at least 12 x 10. He said he got it out of the tank plant in the 80's when they no longer needed it. He also scored a MASSIVE (again, at least 12 x 10) Granite plate. I mean, i've NEVER seen something that big. He has had people look at the Cast Iron plate, but not the granite...at over 20 Tons the Granite plate is SUPER impractical for almost anybody anymore. He jokes that he's going to turn it into the family grave marker. I couldn't even imagine having that kind of hardware, even when I did small end machine building. I do want the PM lathe he has there, but his son constantly says "No, that's mine". His dad continues to say "I'm going to sell it to him if you don't get it the h3ll out of here". BTW: He's closing the shop this year or next. :( Maybe I'll go over and see what kind of goodies I can get. :)
Keith, when I was a youngster, car enthusiasts used to LIKE engine blocks from a car that had experienced an engine fire, just because the heat had removed all the deformation. Yes, it needed machining, especially the main journal area, and the cam area. Cast Iron is an interesting animal. I'm quite a fan of the OLD ShopSmith multi-tools. They used a LOT of Cast Iron. (The sign in for the Model 10, [10e and 10er] Forum, is Cast Iron.) steve
Well done Keith on beginning your weight-loss journey. I lost weight, 110lbs with KETO. A word of advice. You will get heaps of loose skin. I strongly advise you to start a weight lifting program as soon as you fully recover from the surgery. You are never too old to start at a gym. About 30-40 minutes, 3 times a week is plenty. I went back to the gym at age 50.Now as a 56 year old, in certain lifts (the squat) I not only keep up with the kids, but outlift them.
My first job out of high school was for a machine tool rebuilder. They had a big granite surface plate, maybe 10ft long and a lot of cast iron plates of all sizes. They had precision lasers, precision levels all kinds of camel back straight edges... They also had a huge Favretto way grinder that they would use on big machines. When they needed to do precision measuring it was on the granite. When they needed to scrape in ways, tables or parts they used the cast iron. Every now and then they would do the 3 plate scrape in, to recalibrate them. I learned a lot there but I was a stupid kid and changed jobs.
The place that I work at has many of these. One was headed to the dumpster, so one of the guys grabbed it for a welding table. It's the size that you have.
As always a very informant video from Keith.. He is the man to look to and contact when you you need the facts from the way back in time and what we also what is acurate today when you are working with heavy machine's for your machineshop.
Enjoyed the video nice to know why there not a lot of cast iron surface plate Around last place I worked at they put it in a storage build , had stuff piled on it
and I see there that wonderful book... such a fantastic read about "how to start a machinery manufacturing company" without meaning to be so. It's worth noting also that another factor wher cast iron outperforms steel is vibration damping, which is another good reason to use it for building machine tools
This was really interesting. I had the chance to install some signs at an aircraft parts manufacturer a few months ago, and they used a granite plate as a reference but had an old Air Force 6ftx12ft cast iron surface plate for absolute accuracy. It was scraped to an overall flatness of 1050 (grade AA). For reference the highest grade I've ever heard of is a 1100 overall flatness, I don't know if it's even possible to make one better. They said that using the cast iron plate is required by the FAA for absolute accuracy in turbine parts, since they are machined down to a +/- .0005 threshold. I honestly thought cast iron was inferior until they explained that in a climate controlled room, it needed less maintenance and was easier to clean. The only downside is that it should never be moved once installed and flattened. even a grain of sand under the leg can throw it off over time. mainly because it deform the feet and cause raised edges that will make it unscrapable until the feet are remachined flat.
The cast iron ones are also great because you can use them as a nice fixture plate for welding. Now how many people just cringed at the above sentence? :)
You got the trifecta. The brass pin made the difference. I'm kind of a shiny tool guy, but the bluing made it look original but didn't hide your surface finish. Great job!
We have loads of medium size cast iron surface plates at my workplace, they're used for inspection near the machines (mostly with a height gauge and some jigs for the parts), and if you need more accuracy we have multiple CMMs for that.
I had a very talented friend who served his machnists apprenticeship at the old Frankford Arsenal in Philadelphia. He said they would place raw cast iron on the roof for at least a year to think he said to season it. I have done electrical work in machine and tool & die shops and amazed that they had a company to come in once a year to check surface plates and place a dated sticker on them if they passed. Never saw a cast iron surface plate. Great vidio.
Rough castings right out of the sand are FULL of stresses. Either you "season", as Frankford did, or you employ sophisticated thermal cycling, like Clarke Easterling does.
I know of two HUGE Starrett granite surface plates that have been sitting at an abandoned machine shop site, outside in the Iowa weather, for 30 years. The small one is at least 4' x 8', and large one substantially bigger. Check out 41°58'34.24"N 91°35'10.93"W and zoom way in.
No sir, you can cause a localized swelling on granite plate. Doall makes a small black granite gage block stone - used to remove positives. Iv'e use to stone down around such divots on black granite. They are known for being softer than the pink granite, for instance. Thanks for your informative comparison of reference surfaces.
How interesting that cast iron maintains flatness better than granite over temperature changes! I always thought of granite as being immune to thermal variations, the fact that it isn’t is really interesting to me. (Not that I’ll ever do anything that even a grade B plate wouldn’t be massive overkill for, but I’m a measurement geek, so so this sort of thing is fascinating to me 😁) Thanks for a great video as always!
Quite so. Even moving a granite to a different location on your shop floor, or jacks under the plate require calibration to assure plate is still to desired flatness after relaxing into new location. We're talking millionths here. Wouldn't matter for what I was doing in my shop; mattered to the aerospace shops I've worked in.
Working at Kearney and Trecker I can attest to the fact steel weldments were a different animal. Cast iron was more stable, as machines would heat up tolerances would change with the steel til it leveled out.
I picked up a tablesaw wing from work, almost 2 feet by almost 3 feet. Cast Iron, and I don't know what it came off of. If I can get it to within 0.001, I'll be happy. I will not need much more tolerance than that. I work at a woodworking store that sells machines, and hardwood lumber. I repair (customer's stuff) and refurbish (consignment stuff.) I ALWAYS hit the top of a tablesaw, with a fine stone I have, just for that purpose. I see the same exact thing you have shown, where a burr was kicked up. I do NOT like sanding down the whole table, especially if there is a shiny patina there. That stone doesn't harm the patina. steve
Temperature is a constant that effects a lot of measurements,the set of gage blocks are most accurate at 68*f according to the information on the sheet on the box
It would be interesting for you to demonstrate how to use a surface plate for inspections. Many years ago the shops I worked in we used the surface plate to do layouts of one off or small numbers of parts.
I use mine as a welding table. I coat it with anti spatter gel. I don't weld to it, just weld on it. I cleaned my medium rust off (when I got it) using paper towels soaked in vinegar. For the metrology I use a granite plate. I think my cast iron plate is 18x18.. It weighs quite a bit.. I think about 80lbs maybe more. I would like to clean up the bottom and paint it because it's out in the garage.. but I've had it for so many years and have never gotten around to it, and probably won't.
Very interesting that granite plates became popular in the USA decades before they did in the UK. I never saw a granite plate in any of the engineering works I worked in until the 1990's. Even then it was only really the beds on CCM machines andi think there were a couple in the metrology lab. Crown Windley still makes cast iron plates in reasonable numbers now but also supply granite as a lower cost option.
Sadly, two or three of these went to the junk yard from the place where I used to work. Nobody wanted them. I did, but had no place to store them. These are good layout surfaces.
I have a little 12x18 cast iron plate. I was told the smaller ones were used to drag across the larger ones, but I have no idea whether that's true. I like mine--similar patina to yours. It came with a nice wooden cover already built, which makes sense, since it came from an old boatyard.
I have two cast iron surface plates and one granite surface plate. Your testimony to cast iron makes me reconsider the value of my cast iron. My last CI plate is small and was an auction purchase whim ($7). My years in the shop was entirely dismissive of CI. I suspect my "oldest" CI plate is low accuracy. It includes T slots. I don't know its original purpose. I thought it was a cheap investment into hobby shop capacity with machinery that couldn't boast high precision due to its inferior design, age or use/abuse. I own some of this level machinery in my hobby shop. I have often wished that a surface plate had mag base functionality. Maybe it is time see if my CI plates warrant more affection.
Several years ago I purchased a new cast iron surface plate from a manufacturer in China. The make various sizes from small to huge and was very reasonable.
At the 10 minutes of the video I noticed that it is mentioned. " the surface plae will crown or convex " . In my opinion he should have said that it will " crown or concave ", To crown or covex is the same direction. Crown or concave are opposite to each other.. Even though this is a fine video.
Cast iron plates are the best if you need to use them for lay out. I work in fabrication and they are the best because they're obviously magnetic. We can use it as a standard surface plate with height gauges etc. But then we can also use it for laying out components and use magnets to find edges of plots.
I prefer granite to cast iron for several reasons but mainly bc one they don't rust and two if something is accidentally dropped onto it a cast iron which could leave a raised edge/high spot whereas the granite might chip but there won't be a raised edge. Edit* Of course you talked about my main issues LOL
Granite in general is less changing its size due to temperature than iron. But the granite surface plate is thicker and its heat conductivity is smaller. It takes longer to come into equilibrium. Of most concern are directed infrared rays from sun through windows or from any kind of furnace.
It's a good layout surface. Your shop is getting crowded so putting it on a wheeled stand is probably a good idea. I'm thinking that you need an addition dedicated to the keeping those plates. If someone wants a cast iron welding table, go to Fireball Tool.
Size for size the granite will weigh less than a cast iron plate. It's not often noted, but granite and aluminium are nearly identical in density. Of course, granite is far more rigid than aluminium.
Maybe you should just leave it on the roll-around lift table you have it on now, having an height adjustable work table would really be handy. You would have to head to Harbor Freight to get another hydraulic cart but not too big of a deal. You would still have to build a wooden cover for the cast iron plate but you already said you need to do that. Interesting, Thanks for sharing.
I would like a surface plate, just a small one and I wondered about old cast iron ones, probably more than good enough for my work. What I was wondering though was about rust. If you cover the table and perhaps dont use it for months do they rust, how would you stop it and would it ruin the table?
You forgot to mention the biggest advantage of granite plates: they have much better wear resistance! Cast iron is very soft and if you are going to put dozens of heavy parts on such a plate every day and slide them around to take your measurements then you will very soon find out that you now have a measureable valley in the middle of the plate while under the same load a granite plate would still largely maintain its flatness. Cast iron plates make for good master surfaces but if you want to use them for routine work then you will end up having to regularly check and scrape them. It was what they did 100 years ago but in the modern era of disposable tools and instruments it is just way too much maintenance for any industrial use. That is the main reason why noone uses big cast iron plates anymore and only the smallest ones are still somewhat popular because of the great advantage of being portable and comparatively lightweight.
If you ever decide to give up your day job, you'd make a tremendous instructor. You take the time to research your subject matter before spouting off what you've found out. You also have a passion for the subject material. Let's face it, you've been part of several machine scraping classes and I'm sure that in those 5 days for each class, not everything is, or even can be, covered. I never tire of hearing you talk about these things. Keep it up! Hope your recovery continues to go well.
That's kind of what he did. He tried from teaching a&m and runs an educational website and RUclips channel. He occasionally works at the Georgia museum of agriculture doing machine work and such. I would guess he considers this kind of thing his day job though.
Yes, mechanical accuracy, flatness etc and temperature dependence is a rabbit hole one may never emerge from. Very good background and history lesson, thank you!
Nice find. I was recently in a shop of an older gentleman who builds and repairs some high-end race cars, and he had a cast-iron surface plate for inspecting for damage and alignment. He said it was 10 feet by 20 feet. The side rails under the perimeter of the top looked to be about three feet tall. I can only imagine how heavy this thing had to be.
Heavy enough to influence the orbit of the earth based on where it is sitting, I reckon. That's just plain huge.
If you dont need extreme accuracy, a piece of 3cm granite from your local granite countertop shop is great, pick the closest tightest grain structure you can find in the scrap 'black absolute' is one of the best but other colors work great. Ive use it for lapping and scraping parts in with no issues, ex exhaust manifolds, headder flanges, filter housing mating surfaces, carb bases, water outlets and such.
For lapping components like carb mounting faces, oil pump faces, small heads, etc I just use a plate of glass.
A friend of mine went to a company that made tombstones. He got one where they misspelled the name of the deceased, it was really cheap. He then lapped it in.
Tempered glass works in a pinch too.
@@transmaster perfect scrap material for this purpose a mistake in a headstone cannot be fixed it must be replaced, theyd sell it to you for a song lol!
I'd be careful with glass plates, they are more flexible than you might think. Also the flatness isn't that great, I built a simple device for measuring flatness and tested a pane of glass, the indicator jumped all over the place even if it seemed to be flat.
Anyway, I built a simple surface plate out of a broken granite tile (actually two, both halves were usable). The surface was somewhat ground already, but just to be sure I got some abrasive powder (silicon carbide) and lapped both plates onto eachother. The result turned out pretty good. It's not perfect, but I'd definitely trust it way more than a piece of glass.
Glad you're feeling better, sir.
One option I didn’t hear; portable propane shop griddle. You’d have the most precise pancakes around.
Keith a very useful ready reckoner for Fahrenheit to Centigrade is that 61ºF = 16ºC and 82ºF = 28ºC and then just interpolate between the two sets of equivalents.
C = (F-32)*5/8
F=8/5*C +32
Straightforward conversion every schoolboy knows
@David Martin actually it's 9/5 and 5/9, but you're right otherwise.
@@davidmam I think the conversion factor is actually 5/9 not 5/8. But therein lies the difficulty because it’s hard to remember! Otherwise I’d agree with you that the math isn’t too scary.
quick and dirty for C to F double the c and add 30 ,not completely accurate but near enough plus its a easy in the head one works the other way also - 30 / 2
Negative 40 is negative 40, in both.
steve
Great information Keith, learned something new about the difference between those materials. Concerning the moving cart, use large wheeled castors that won't get hung up on small bits left on the floor. That thing has "top heavy" written all over it. Pretty sure you already thought of that but a reminder doesn't hurt.
Thank you Keith. This was great information and well presented. It also has an "Aboms, eat your heart out" bonus on this beautiful plate!!
My father was a Electrcal Engineer Inspector and his standard instruments were kept in the "Standards Room" never to leave at a constant temperature of 68F or 20C. Before he retired he took me on a visit to see all the amazing testing equipment they had. The most interesting for me was a 7KW lamp to imitate the sun and a Catapult Room with a sled on rails for acceleration measurements.
Nice find! I was a scraper hand at a machine tool rebuilding shop in Cleveland Ohio in the 70's. My shop had a beautiful 4'x8' scraped cast iron plate, the master of the shop full of many smaller surface plates, straightedges, and squares. It was treated as such, not used for storage, and always clean. I have also used granite, but find a scraped surface a little better for spotting, the transfer of the blue marking medium for the piece being scraped, that's just my opinion.
I love the machining videos you produce, but I'm never disappointed with a talky one. Your enthusiasm is infectious, your teaching style engaging and your subject matter always of interest. Nice purchase.
Very well stated !!
We have a cast iron one at the shop I work at. Its 4’x6’. Hasnt been lapped in years and hasnt been used as as surface plate for a long time. Mostly used as a workbench now. We have a few smaller granite surface plates for inspection use.
A great video Keith! So much information about the merits of cast iron versus granite surface plates. I've only room for a 12" x 12" granite in my tiny, tiny shop 7' X 5' yes that small in which I have a 12"x 19" lathe with a milling machine attachment. All the rest of my machinery is outside under cover lol. When I used to be a teacher we had a brand new 24"x 24" cast iron surface plate on a cast stand about 38" high and apart from myself on personal projects I only ever saw it used a couple of times by students. (My head of department taught the senior year examination students ) now it has probably been scrapped along with a 9" Viceroy Shaper, and a Tom Senior Horizontal mill that I was the only one to use. ( until I left of course) there were also 4 , 12"x and at least 24"lathes. One with a vertical milling attachment. Again I was the only one to use it in the 10 years I was there. All probably scrapped or just sold off. What a bloody waste!
"The Fundamentals Of Mechanical Accuracy", is simply one of the most fascinating technical books I have ever read. A must read for any machinist indeed just about anybody fullstop! Thanks for the great video
Hmm, I still have the sink plug that came out of our granite counter top and I’ve been thinking about what to do with it. Now I at least have an idea. Great video.
absolutely!! use it for typical shop needs those are really good surface plates for us hobby shop machinists/mechanics. Ive used one for years and it works great!
Great video Keith
my dad was a Fitter at the same iron works as I served my time as a sparks . away I digress the fitting shop had the old fashioned oak block floor end grain up set on pitch ( nice for the legs and does not ding your tools ) the surface plate was some 20 foot by 12 foot and was constructed on a raised concrete slab, said to be six foot deep, the interesting thing was the cast iron top was made up of separate CI cubes about 1 * 1 * 1 foot , it was used to sett up for machining large casting for the items they assembled , the overhead crane had two blocks one 5 ton and the other 20 ton ( that's 2240 pounds ton ) , I never knew how good it was
Having a small home shop I cheat and use my cast iron table saw surface. I found this flatter than the granite "scrap". I have also used a wing of my 8" jointer for longer items. For the very few times, I have needed an accurate surface this has saved the day.
I picked up a 16" x 16" cast iron plate with a wooden cover from an auction. I wasn't planning on buying it, but no one was interested and got it for next to nothing. As i'm a novice engineer, I have yet to used it in anger, however there's been several times when it's been useful for lapping on emery (had been using glass). I doubt it's accurate, but well within the tolerances I will be doing.
I'm really hoping Adam finds something similar and Keith would be willing to do a swap, to keep a tool that gramps might have used in the family.
I really enjoyed the historical context in this video. I also liked the way that you worked in the macro shots of the surface plate details and the pages of the book. It must take lots of time to edit those details into the video, but I feel that it really adds to the quality of the video. Thanks again for the great content!
Semi-related. We needed a 3x4 inspection surface for 120 pound ceramic objects to be sure the bottoms of the objects were flat within +/-0.06. Unglazed fired ceramic is extremely abrasive. I have purchased many surface plates both granite and, years ago, cast iron. Anything we used for a table would be highly abraded. So standard surface pates are not suitable. Granite surface plates would last only a few days. I searched for an old worn-out / damaged cast iron plate or machine base that could be repeatedly ground back to flat as it was worn from use. No such animal in the budget cost range. I resigned to building a cheap temporary table from steel. A local shop said they had a piece of WWII Sherman tank armor in their parking lot for years. They wanted it gone and at scrap steel prices. Could I use it for the inspection table if I altered some of the dimensions? Sure. I had the armor Blanchard ground both sides so it could be flipped over when one side wore out.
Wow! After thousands of heavy parts dragged around on the table, the surface was still flat within +/- 0.0001 after 3 years. Did not have to flip it over and use the other ground surface. Absolutely amazing. I have seen cast iron and steel worn -0.01 after a few hundred heavy ceramic parts.
Too bad the project is complete. Would like to keep that inspection table for the next future job.
Yeah no doubt. Armor plating is just that, armor. Hardened tool steel essentially. Ceramic will cut or abrade most anything. Even considering the plate was designed to stop ordnance, it's still impressive it stood up to 3 years of what amounts to the worst possible conditions outside of what it was made for. Pretty awesome.
I saw a 4x8 iron plate posted locally for scrap cost. I believe it was several tons and stood at bench height without legs.
If I had room for it, I would own it for the simple fact they look cool. Until i have more room, my little bench top iron plate will do.
That book is an incredible source of information and is a fascinating read. Nice to see it being mentioned here. I enjoyed this video, thanks for producing it.
You never really gave me the WHY but THANKS for the vid
Loved this video. It was a walk down memory lane for me. During the 1970s I worked for a UK company that made cast iron surface plates. 10"x 8" through to 48" X 24". Yes cast iron is a very messy material to work with.
I'm sorry to say the company has been gone for many years now.
I read "Machine Tool Reconditioning" by E.F. Connolly back in the eighties to check and correct all my machine tools. It's the best I ever read, probably similar to the one you show. When I got mine, I found a "carpet sample" at a flea market that was an exact fit for my 18 by 24 plate. I've had it for almost forty years, very handy to have for general machine work and for testing/try fit of precision fits. Before I found the granite, I had an apron from a large lathe, about three foot by one and a half, I scraped flat and true, used for ten or fifteen years.
Thanks Keith you are looking good . Hi from the land down under
That looks just about perfect for building model aircraft on, I need one of those!
Keith, very much enjoyed this ‘lecture’. Thank you …
A very sentimental old master, salute
Just ordered that book you referenced. Very expensive but right up my street. I remember my dad telling me that cast iron plates needed to be made in threes. My cast iron plate is only 12” by 12” and would have been purchased second hand in about 1950. When i get my precision ground stones i will certainly check for any high spots although the plate has a wooden cover which both my father and i have been careful to always used. Very interesting video!
Thanks Keith. Great explanation!
Friend's dad owns a "Machinery Rebuilding" place...OK, so they USED to rebuild A LOT. They now do more reselling and sourcing than anything. He has two MASSIVE surface plates, one is Cast Iron and it HAS to be at least 12 x 10. He said he got it out of the tank plant in the 80's when they no longer needed it. He also scored a MASSIVE (again, at least 12 x 10) Granite plate. I mean, i've NEVER seen something that big. He has had people look at the Cast Iron plate, but not the granite...at over 20 Tons the Granite plate is SUPER impractical for almost anybody anymore. He jokes that he's going to turn it into the family grave marker. I couldn't even imagine having that kind of hardware, even when I did small end machine building.
I do want the PM lathe he has there, but his son constantly says "No, that's mine". His dad continues to say "I'm going to sell it to him if you don't get it the h3ll out of here". BTW: He's closing the shop this year or next. :( Maybe I'll go over and see what kind of goodies I can get. :)
You should restore it and give it to Adam booth, it would mean the world to him.
Wonderful! Thank you Keith!
Keith, when I was a youngster, car
enthusiasts used to LIKE engine
blocks from a car that had
experienced an engine fire, just
because the heat had removed
all the deformation. Yes, it needed
machining, especially the main
journal area, and the cam area.
Cast Iron is an interesting animal.
I'm quite a fan of the OLD ShopSmith
multi-tools. They used a LOT of Cast
Iron. (The sign in for the Model 10,
[10e and 10er] Forum, is Cast Iron.)
steve
Well done Keith on beginning your weight-loss journey. I lost weight, 110lbs with KETO. A word of advice. You will get heaps of loose skin. I strongly advise you to start a weight lifting program as soon as you fully recover from the surgery. You are never too old to start at a gym. About 30-40 minutes, 3 times a week is plenty. I went back to the gym at age 50.Now as a 56 year old, in certain lifts (the squat) I not only keep up with the kids, but outlift them.
Keith, I'm sure the past weeks have been hard physically, but I must say that you're looking really good. Recover on!
Thank you for the info. I never have or never will use a surface plate but I like knowing the differences.
My first job out of high school was for a machine tool rebuilder. They had a big granite surface plate, maybe 10ft long and a lot of cast iron plates of all sizes. They had precision lasers, precision levels all kinds of camel back straight edges... They also had a huge Favretto way grinder that they would use on big machines. When they needed to do precision measuring it was on the granite. When they needed to scrape in ways, tables or parts they used the cast iron. Every now and then they would do the 3 plate scrape in, to recalibrate them. I learned a lot there but I was a stupid kid and changed jobs.
Excellent fine gorgeous piece of castle Love to find one of those thanks for the video
The place that I work at has many of these. One was headed to the dumpster, so one of the guys grabbed it for a welding table. It's the size that you have.
Great tutorial for me Keith.
Thanks for sharing.
As always a very informant video from Keith.. He is the man to look to and contact when you you need the facts from the way back in time and what we also what is acurate today when you are working with heavy machine's for your machineshop.
Great content. Thanks for posting, I learned quite a bit
Enjoyed the video nice to know why there not a lot of cast iron surface plate
Around last place I worked at they put it in a storage build , had stuff piled on it
and I see there that wonderful book... such a fantastic read about "how to start a machinery manufacturing company" without meaning to be so. It's worth noting also that another factor wher cast iron outperforms steel is vibration damping, which is another good reason to use it for building machine tools
Good video, nice new toy!
This was really interesting. I had the chance to install some signs at an aircraft parts manufacturer a few months ago, and they used a granite plate as a reference but had an old Air Force 6ftx12ft cast iron surface plate for absolute accuracy. It was scraped to an overall flatness of 1050 (grade AA). For reference the highest grade I've ever heard of is a 1100 overall flatness, I don't know if it's even possible to make one better. They said that using the cast iron plate is required by the FAA for absolute accuracy in turbine parts, since they are machined down to a +/- .0005 threshold. I honestly thought cast iron was inferior until they explained that in a climate controlled room, it needed less maintenance and was easier to clean. The only downside is that it should never be moved once installed and flattened. even a grain of sand under the leg can throw it off over time. mainly because it deform the feet and cause raised edges that will make it unscrapable until the feet are remachined flat.
Very interesting. I wouldn’t have guessed that iron was better.
The cast iron ones are also great because you can use them as a nice fixture plate for welding.
Now how many people just cringed at the above sentence? :)
Great video! If one wants a welding table, two words... ACORN PLATE!!
You got the trifecta. The brass pin made the difference. I'm kind of a shiny tool guy, but the bluing made it look original but didn't hide your surface finish. Great job!
We have loads of medium size cast iron surface plates at my workplace, they're used for inspection near the machines (mostly with a height gauge and some jigs for the parts), and if you need more accuracy we have multiple CMMs for that.
Thanks for the history lesson Mr Rucker 👍. By the way it reminded of Dan Gilbert, he built the ways of his lathe out of granite.
I had a very talented friend who served his machnists apprenticeship at the old Frankford Arsenal in Philadelphia. He said they would place raw cast iron on the roof for at least a year to think he said to season it. I have done electrical work in machine and tool & die shops and amazed that they had a company to come in once a year to check surface plates and place a dated sticker on them if they passed. Never saw a cast iron surface plate. Great vidio.
Rough castings right out of the sand are FULL of stresses. Either you "season", as Frankford did, or you employ sophisticated thermal cycling, like Clarke Easterling does.
I know of two HUGE Starrett granite surface plates that have been sitting at an abandoned machine shop site, outside in the Iowa weather, for 30 years. The small one is at least 4' x 8', and large one substantially bigger. Check out 41°58'34.24"N 91°35'10.93"W and zoom way in.
No sir, you can cause a localized swelling on granite plate. Doall makes a small black granite gage block stone - used to remove positives. Iv'e use to stone down around such divots on black granite. They are known for being softer than the pink granite, for instance.
Thanks for your informative comparison of reference surfaces.
Great video Keith, keep'um coming..
You look really great Keith! Thanks for posting this, very informative. I have both types in my shop.
How interesting that cast iron maintains flatness better than granite over temperature changes!
I always thought of granite as being immune to thermal variations, the fact that it isn’t is really interesting to me. (Not that I’ll ever do anything that even a grade B plate wouldn’t be massive overkill for, but I’m a measurement geek, so so this sort of thing is fascinating to me 😁)
Thanks for a great video as always!
Quite so. Even moving a granite to a different location on your shop floor, or jacks under the plate require calibration to assure plate is still to desired flatness after relaxing into new location. We're talking millionths here. Wouldn't matter for what I was doing in my shop; mattered to the aerospace shops I've worked in.
Working at Kearney and Trecker I can attest to the fact steel weldments were a different animal. Cast iron was more stable, as machines would heat up tolerances would change with the steel til it leveled out.
Nice !
Thanks - I learned something today!
Thank you for sharing. Enjoyed.👍
I picked up a tablesaw wing from work, almost
2 feet by almost 3 feet. Cast Iron, and I don't
know what it came off of. If I can get it to
within 0.001, I'll be happy. I will not need much
more tolerance than that.
I work at a woodworking store that sells
machines, and hardwood lumber. I repair
(customer's stuff) and refurbish (consignment
stuff.) I ALWAYS hit the top of a tablesaw, with
a fine stone I have, just for that purpose. I see
the same exact thing you have shown, where a
burr was kicked up. I do NOT like sanding down
the whole table, especially if there is a shiny
patina there. That stone doesn't harm the patina.
steve
I was thinking Adams Grandfather could have used it also. And another advantage is Granit doesn't rust.
Always wondered about temperature change and stability.
Interesting!!
Temperature is a constant that effects a lot of measurements,the set of gage blocks are most accurate at 68*f according to the information on the sheet on the box
Book arrived safely in johannesburg on 27/1/2023. Most expensive book i have ever purchased!
It would be interesting for you to demonstrate how to use a surface plate for inspections.
Many years ago the shops I worked in we used the surface plate to do layouts of one off or small numbers of parts.
Looking good Keith! Thanks for the info. I wondered about the differences.
I use mine as a welding table. I coat it with anti spatter gel. I don't weld to it, just weld on it. I cleaned my medium rust off (when I got it) using paper towels soaked in vinegar. For the metrology I use a granite plate. I think my cast iron plate is 18x18.. It weighs quite a bit.. I think about 80lbs maybe more. I would like to clean up the bottom and paint it because it's out in the garage.. but I've had it for so many years and have never gotten around to it, and probably won't.
Very interesting that granite plates became popular in the USA decades before they did in the UK. I never saw a granite plate in any of the engineering works I worked in until the 1990's. Even then it was only really the beds on CCM machines andi think there were a couple in the metrology lab. Crown Windley still makes cast iron plates in reasonable numbers now but also supply granite as a lower cost option.
That plate would make a beautiful coffee table for coffee table books……..like Foundations of Mechanical Accuracy.
Nice! Though the misses might not agree
@@zHxIxPxPxIxEz I’ll let her put some flowers on it as well.
Sadly, two or three of these went to the junk yard from the place where I used to work. Nobody wanted them. I did, but had no place to store them. These are good layout surfaces.
The book is available on order from Moore Tools for $150 USD.
Really interesting video cheers Keith
Saw a plate similar to that one in a navy small engine shop. was used to measure heads for warpage
One advantage of the cast iron plate is that you can clamp instruments with magnetic bases to it.
I have a little 12x18 cast iron plate. I was told the smaller ones were used to drag across the larger ones, but I have no idea whether that's true. I like mine--similar patina to yours. It came with a nice wooden cover already built, which makes sense, since it came from an old boatyard.
I have two cast iron surface plates and one granite surface plate. Your testimony to cast iron makes me reconsider the value of my cast iron. My last CI plate is small and was an auction purchase whim ($7). My years in the shop was entirely dismissive of CI. I suspect my "oldest" CI plate is low accuracy. It includes T slots. I don't know its original purpose. I thought it was a cheap investment into hobby shop capacity with machinery that couldn't boast high precision due to its inferior design, age or use/abuse. I own some of this level machinery in my hobby shop. I have often wished that a surface plate had mag base functionality. Maybe it is time see if my CI plates warrant more affection.
Several years ago I purchased a new cast iron surface plate from a manufacturer in China. The make various sizes from small to huge and was very reasonable.
The Abom connection is wonderful…
KEITH GREAT FIND, GLAD YOU ARE DOING FINE, TELL ALL HELLO...SEE YOU WHEN...
At the 10 minutes of the video I noticed that it is mentioned. " the surface plae will crown or convex " . In my opinion he should have said that it will " crown or concave ",
To crown or covex is the same direction. Crown or concave are opposite to each other..
Even though this is a fine video.
Cast iron plates are the best if you need to use them for lay out. I work in fabrication and they are the best because they're obviously magnetic. We can use it as a standard surface plate with height gauges etc. But then we can also use it for laying out components and use magnets to find edges of plots.
I prefer granite to cast iron for several reasons but mainly bc one they don't rust and two if something is accidentally dropped onto it a cast iron which could leave a raised edge/high spot whereas the granite might chip but there won't be a raised edge.
Edit* Of course you talked about my main issues LOL
rust is indeed a problem for most of us home shops!! so yea granite for me too!
Granite in general is less changing its size due to temperature than iron. But the granite surface plate is thicker and its heat conductivity is smaller. It takes longer to come into equilibrium.
Of most concern are directed infrared rays from sun through windows or from any kind of furnace.
An advantage of cast iron is ...
It's magnetic
Some times pretty handy for measurement
It's a good layout surface. Your shop is getting crowded so putting it on a wheeled stand is probably a good idea. I'm thinking that you need an addition dedicated to the keeping those plates. If someone wants a cast iron welding table, go to Fireball Tool.
If you are going to put it on casters then make sure it’s chained down when Adam visits 😂
Interesting... 🙂
I have a glass surface plate from the 1940's ,which was another alternative to the cast iron
Size for size the granite will weigh less than a cast iron plate. It's not often noted, but granite and aluminium are nearly identical in density. Of course, granite is far more rigid than aluminium.
Maybe you should just leave it on the roll-around lift table you have it on now, having an height adjustable work table would really be handy. You would have to head to Harbor Freight to get another hydraulic cart but not too big of a deal. You would still have to build a wooden cover for the cast iron plate but you already said you need to do that. Interesting, Thanks for sharing.
Good morning everyone
I would like a surface plate, just a small one and I wondered about old cast iron ones, probably more than good enough for my work. What I was wondering though was about rust. If you cover the table and perhaps dont use it for months do they rust, how would you stop it and would it ruin the table?
You forgot to mention the biggest advantage of granite plates: they have much better wear resistance! Cast iron is very soft and if you are going to put dozens of heavy parts on such a plate every day and slide them around to take your measurements then you will very soon find out that you now have a measureable valley in the middle of the plate while under the same load a granite plate would still largely maintain its flatness. Cast iron plates make for good master surfaces but if you want to use them for routine work then you will end up having to regularly check and scrape them. It was what they did 100 years ago but in the modern era of disposable tools and instruments it is just way too much maintenance for any industrial use. That is the main reason why noone uses big cast iron plates anymore and only the smallest ones are still somewhat popular because of the great advantage of being portable and comparatively lightweight.