Repairing & Re-Grinding The Okamoto Surface Grinder!
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- Опубликовано: 6 сен 2024
- Recovering from a devastating discovering: a rusted surface grinder table. Follow along as we wire wheel, scrap, grind, clean and adjust to get the Okamoto Surface Grinder back in good working order. Finally, checking the results with a 5-block test!
The Grinding Wheel (Book): amzn.to/2uemqnL
LPS3: amzn.to/2vnhZW0
Cheap 1-2-3 Blocks: ebay.to/2gNqsPa
Mitutoyo 0.0001 DTI: amzn.to/2tiSC6s
Noga Mag Base (FINE adjust TOP!): amzn.to/2gNq3fq 5 Reasons to Use a Fixture Plate on Your CNC Machine: bit.ly/3sNA4uH 
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Good one!
While I do the 5 block test myself, it can be misleading. It tells you only that you grind parallel, it is not a direct indication that you grind straight. That can only (well, not only) be tested with a straightedge/parallel as you showed earlier in the video.
The 5 block test is great to show that you ground the mag chuck properly.
Good to see Richard in the background :D
John: One of the hardest lessons to fully learn (and most applicable) about metrology, is that there is no such thing as "perfect", only a higher degree of resolution necessary to observe actual variation from a desired optimum.
i looked like you were reciting a bible passage when you read that piece about the grinding wheel lol
Amen to that.
its taken from the old testiment ..! thats correct. Never run a machine without coolant it's the 11 ( not in the book no more ) Updated version.
......pass the grinding plate.....
wait, he wasnt? ;P
Yeah take a good look and also listen to "Priest" when he reads loud from the Machine Bible.. it's more holy than the Quran this book :D
professional way of inspecting ground, scrape and lapped surface. I like that.
Grinders take some time to warm up. Wheel bearings, slides everything.
A good half hour to an hour of letting the grinder warm up to temp and stabilize before you grind anything is a good idea.
Even cold hydraulic oil can cause noticeable thermal movement mid way thru grinding as it warms up and shifts things.
John, something that would have prevented that problem all together is laying down a good corrosion prevention compound on the bare metal under the chuck. I work in the aviation field and we have used many different types of CPC's over the years like that LPS 3 you have in the video (does not work well). What we have found to work the best even in saltwater spray/immersion exposure is corrosion-X. They have something in the solution that not only protects the metal but it will also stop existing corrosion from spreading by neutralizing the acids forming. And to remove rust from metal without changing the dimensions (mechanical removal) we use EvapoRust. No scrubbing no sanding no fuss.
John, I can hear your wheel fail. Cast iron is difficult to grind; you have to dress oftener and take lighter cuts.
Use plenty of FLOOD coolant. Heat is a killer. Warm the table surface with injudicious grinding and the heat expands the surface causing it to hump up under the wheel. Then you carefully grind this hump flat with great care and precision. Later when the table gets back to thermal equilibrium the once-expanded surface sucks back from flat to concave.
I suggest a coarse dress and grind no more than one cross slide reversal per dress. Use about 7/8 wheel width cross feed increment. No more than 0.0003" down feed on the final cuts and just beause you're removing so little stock doesn't mean the wheel isn't wearing on the cutting tips of the abrasive. Dress often even if it is a PITA.
It can take a couple hours to do a clean, stress-free job of grinding a surface grinder table.
Bed the clean, fresly stoned mag chuck on a heavy fresh film of a good heavy grease-like metal preservative. I prefer LPS3. Install the chuck while the preservative is still very fluid, otherwise it will take hours or days for the excess to squeeze out. Enen then, don't grind the chuck until the next day when the grinder has reached thermal equilibrium and the preservative film has had time to gel. Apply an asphaltum based automotive undercoat to the exposed T-slots and clamps. Years from now an hours long soak with WD40 will soften the undercoat so you can service the chuck. I guarantee there will be little rust under the chuck.
And yeah, I think you're right: that description you read of the way a grinding wheel ideally breaks down is written in words of gold.
.
Definitely not enough coolant. Too fast cross feed and too fast cross feed on the dressing. Also want to make sure you have a good diamond as a dull one will not open the grain of the wheel properly.
I'm sure I'm late to the party but I work in the optical field as a toolmaker. There's an important aspect to flatness which is shape. When that magnet pulls and your chucks shape is bad you'll get all kinds of poor results. See about making a spherometer and checking the shape of your chuck. Then you're getting into serious precision territory. Keep up the great work!
Your actual error is .00035 though so you still are off almost 4 tenths. Keep tweaking you will get there! :-) Obviously you have made a hug improvement in it. When you grind you want to barely dust it. If it is barely sparking it is perfect for truing up. Also I run my spindle for a while before starting to grind and also go ahead and run the flood coolant all over the chuck, it will help to equalize the temp. Once you get it grinding parallel then you can try to get it to grind flat! Well I guess after all this free advise I better go tram my drill press! lmao
Beautiful. Grinding is a true art. It delves into a level of accuracy inconceivable to most folks. Just marvelous. A few tenths' error over that size of table is phenomenal as well.
I love your channel. Mostly because you get excited about all the little details that I want to hear about.
Absolutely Awesome!!!
Watching a Surface Grinder is like Meditation to me. *Tick Tick Tick Tick* 😄
I really love old cast iron machines.
Thank You John :)
Hallelujah brother! We are in the church of steel today, brothers. We even got a parable from Abom79. I’m surprised we didn’t get a passage from Tubalcain too.
Put the indicator base on a metal chair OFF the grinding machine. Make an extension if you need to reach then traverse the table in x and y. You can not use the table surface to measure the table surface. It does not matter if the chair is level or whatever you put the magnetic base on.
Wow, how fortunate that the grinder table was salvageable and is now so incredibly flat and accurate!
Lucky day! :)
That is a nice descriptive passage, some of the older books do describe things beautifully. Another thing that often gets forgotten is the state, the sharpness, of the diamond dresser. A sharp diamond will remove the old grit from the wheel while a dull diamond will often push the dull grit back into the wheel and do nothing to clean the wheel off.
Very nice John! A green silicon carbide wheel is your friend on cast iron. I heard there was a grinding wheel & dressing clinic at your open house :)
ATB, Robin
Hi John,
Thanks for presentation.
I have a Grand Rapids 560 12x36 very similar to yours and I just had the magnet off to check for rust and clean because I had just ground a large thin tapered shim by shimming the chuck. The book for my grinder recommends .0002" down-feed to dress the chuck with frequent dressings. The outriggers on it are part of the machine base so no adjustment that I know of.
Good luck.
Eric
That spark is killing me. TOO HEAVY!!!
After everything is done, moving grinder, possible regrind chuck, put silicone around magnet base to machine base, and for some reason, we had read at one time the holding bolts/screws on mag chuck should be of different torque one end to the other, and also we went back and forth about grinding the top of the chuck while it is on/variable etc, and how different a fine pole magnet is to one with bigger gaps? Will try to find that literature? You have done so well, and you really deserve it, I hear you say all the time you are not classically trained, but yet you are a true perfectionist!!!
That sag in the middle of the chuck could have been due to the rust. Rust would have pushed up on the chuck, making it bow upwards. If it was ground in like that it would end up slightly thinner in the middle. When you cleaned out the rust it pulled back straight(er) with the resulting dip in the middle.
Yup, I'm doing this with our grinder at work this week. The underside of the chuck looked very similar to John's.
Grinders are a special kind of magic
After the chuck is back on, Put you indicator in a mag base on the spindle. Get a sharpie and jog the table all over and write the readings right on the chuck. Start at the high spot and drop down .0001-.0003 per pass. Make sure the mag is on when you grind it. I have no idea what you were doing with that straight edge and your mag base on the chuck. Some folk swear by using a layer of crisco on the chuck when grinding it in.
John, Make sure when you install that new grinding wheel to have it professionally dynamically balanced! A lot of people do a static balance and think it's good enough, but if you want the ultimate in ground surface finish, get it dynamically balanced and the results will blow your mind.
I know this post is 10 months old, but is that where the old nerdy guys drag out an oscilloscope and try to identify some kind of frequency? Just from the sound and some equipment, I think.
You confirmed what I would be worried about with a used grinder. I have a line on a similar grinder, but it could end up taking so much time and money 💰. Probably still worth it in the end. Good for you for figuring it out 👊🏽
That was a great video, John. Seriously one of your best ever. Congrats on getting the grinder in shape- literally!!
I agree - one of your best. It was better Hollywood... the horror of that rust, then the whodunit chasing down all the sources of error.
For the condition you restored the grinder to, what sort of precision would you bid a surface ground job for? i.e., would you take on a job requiring you had to deliver a 8" x 8" x 2" tool steel block ground to a 64 finish, flat and parallel within .001"? .0005"? etc.
To paraphrase Dirty Harry, "a man's got to know his machine's limitations" - to bid a job.
Good day when you see any one with that big a smile. Good luck
Will
Hi Jon. Great job. I really like to see you do machining manually. Good thing you have not forgotten. I did start looking at the Cnc videos I need to watch them over and over. Good video.
Bill from Seattle.
Shouldn't you have reground both the table and the chuck after adjusting the outriggers?
Awesome results! I didn't appreciate that the table cross feed was a continuous motion - I thought it was like on a shaper where it only advanced at one end of the stroke. I guess that will produce a sort of zig-zag grinding direction across the work?
I use a Mighty Mag with a diamond mounted in it to dress my wheel. It's really handy when you have a part on the chuck that you don't want to take off just to dress the wheel for a finish pass. Just slap it on the top of your part and go.
Awesome!! I am excited as you are....too cool!
It's heat. It's all about heat. More heat is generated as the wheel breaks down. As the material being ground is heated up it warps, and cools down as you spark out, leaving highs, and lows. You need to rough within about a thousandths then redress the wheel, allow the part to cool, and then hit it about a tenth per pass then spark out and you should have better results. Making passes at about a tenth does not generate as much heat as you dial in your size and gives you a more even and accurate grind.
Hi John,
Looks like you have a nice grinder there. We did a few videos on surface grinding on our channel. Check them out, maybe you will fine a few things that are helpful.
Steve
I agree. The tip about the 46 grit wheel was gold!
Thanks Max.
Thanks, Dave
think even if you lay a washer under one end of the mag chuck as long as you flatten the table to the grinder everything you grind will be level all over as you gauge everything to the grinding wheel , offcourse it IS better to have everything level to start with in case you remount stuff under the stone like the mag chuck
Good on you for taking the time with it.
when you use your grinder, you absolutely need to run it with close to full table limits in X and Y for 10-15 minutes to let the hydraulic fluid get in to all the places its going to get in to. That fluid layer could be as much as .001" and over a 2' chuck could be way more than that. Warming up the grinder lets everything get in to place and get warmed up and get to leveling itself back out. You can't just turn this machine on and expect things to go smoothly. Grinding is an art.
Best stuff I found to loosen rusted parts is Kroil its about $15-20 a pint but is some awesome stuff.
Best to use a cluster diamond on a big wheel, they'll stay sharper and last longer. If you want an aggressive cut dress the wheel fast and for a finer cut dress it slow, also if your wheel loads up to fast use candle wax on the wheel, this application is a must for grinding aluminum or beryllium. Good luck . . . D Oktim
You need to watch Stans channel on wheel dressing. Also use archoil reust remover on the table, you mix with water, does not work with out it. Great video.
Wow that mag chuck is gigantic.
Great testing, great learning experience and most of all, great results!
Unusual good episode! Grinding and tuning the machine is a art.
next time is better you use a level for check the machine table.and also can change the angle of the indicator,like that sometime no so good.better Tesa analogic level and steps by 100mm foe check surface
Awesome! Great video! when you get to that fussy measurements even temperature comes into play! which is crazy!
Yes I agree the temperature definitely comes into play You're on the shop floor it's 90°, then you walk into inspection where it's 70 it makes big difference
You want to do dust cuts .001 is too much 4 a chuck. You want to use water. The heat will cause expansion during the cut the contraction. It is better to use air to blow the coolant into the cut. When grinding a chuck and chuck base feed down of .0002 the one or two spring passes is best. To go past the end of the travel so the vibration of the reverse can settle down. Also for roughing cuts to dress .001 with a steady and kinda quick traverse. Then to finish grind dress .0005 and slowdown the traverse a little to close the grain however doing this will increase heat in the cut. After a finish dress be certain to one pick up the high spot of the surface two only feed .0002 or .0001. Take your time or the wheel will load then you will have warping do to heat transfer. .001 variance on grinding is like .01 in milling or turning.
i dont understand why to put the magnet at the housing because you not only want to make shure that it is flat. also that it is parallel to the grinding ways
was wating to see you dial this machine zero, had no doubt you could do it. skilzzzzzz!
also I forgot when you dress the wheel use a piece of brass and just gently drag it across the wheel to remove any loose material so you don't get those fine gouges in the part if you do all that you will be fine and it will look great.
I wonder why you did not start restoration from grinder's spindle first?
interesting. but the imperial units are a little annoying. in my shop we grind materials accurate to 1 micron. thats about 0.00004 inches
Would have been nice to have an explanation along those "wrong/right" measurements, as others not-in-the-know might wonder why something is done the way it is. For example, when you put the indicator on the wheel head and measure across the bar, you are effectively measuring the tilt due to unknown surface it is resting on and the way wear. But when travelling a small footprint dial indicator mount across the chuck you are measuring relative differences in the chucks surface. Both are good techniques, just hav to be careful in thinking what is actually being measured.
And the two points you were thinking are called Airy points (en.wikipedia.org/wiki/Airy_points), 5/9 of the length of the bar.
And it is a horizontal spindle machine, so the Y is not across the table ;)
Hey John don't use a fine wheel it will just load up too fast I recommend a 46 I wheel and when you get your repeatometer done use that to test it but most jobs .0002 over all will do just fine don't try to get it better than that it will just drive you nuts if you need closer send it to a lapping shop and save your time and energy I can grind stuff to .000001" but it's not worth the time and money lol great video.
Yeah i learned that sorta new to the industry i was taking hours to get it close to perfect i always aim to get everything .00005 across
What kind of coolant are you using now? what type were you using before?
Brother, EVAPORUST! Saw Keith Rucker use it and WOW its amazing, like some kind of magic elixir. 24 hours in that stuff and your cleanup will have been a BUNCH easier. 5 Gal bucket is about $55 from amazon...just sayin.
WOW, under.0002!! From where you started that's amazing.
John at 6:28 why is that the wrong way to measure??
Also the heat can cause grinder cracking.
what wheel did you dress the chuck with? when i did mine, it was a hell of a learning curve doing that(oh and dry as well). also why didnt you grind the bottom of the chuck? PLEASE give any and all insight on grinding wheels, i have started down the rabbit hole, and ITS DEEPER THAN I COULD HAVE EVER IMAGINED!
and I may be getting ahold of you to grind up some new ways for my little taft peirce no. 1. depending on where i end up with mine.
awesome to see that kind of run out, thats a HUGE table.
He did grind the bottom of the chuck.
Jaakko Fagerlund im gonna have to rewatch.
was that thw little clip before checking the table for flatness?
Sweet results!! More stuff for me to test
why do you get more pressure on your indicator in the middle if its low there?
the indicator sinks... got it
great job
Well done! Most interesting!!
I enjoyed the video. Bring the machine back to that accuracy must have been a real deal for you. I live down in Southern Ohio on the river between Portsmouth and Ironton. Have you been well? It may be the camera but you look a bit pale. Hang in there, Greg.
But, does it hinge?
Indicating that straight edge is completely pointless with your indicator on the chuck. What if the left side of the chuck was was high 3"? You would still get a parallel reading to the chuck. You absolutely must indicate off the spindle. Or the side of the spindle or column. That's the only thing that counts.
Super video John. One question..... How do you keep the rusting from reforming on the chuck bottom in the future? More modern coolants? Dono....
Fred Miller if u listen to oxtools Tom Lipton, frog lube
Thank you Bill!
My vote is for Frog Lube. I apply to all my machine that have exposed surface prone to Rust. Frog lube is a Wax (like car wax) so it forms good thin layer of protection. There are many Frog lube torture tests on you-tube, and that last time I checked, nothing beats frog lube.Another good protectant is Fluid film which I use on farm machinery for protecting bolts and other surfaces that are difficult to reach or clean (some rust protectors don't work well on dirty or already rusted surfaces).
Coat it with POR-15. You will never have to worry about corrosion again. The stuff is amazing. I have seen it used on car frames, outdoor machine parts, anything where rust and corrosion is a problem. Problem solved. It costs $50 a quart, but it is worth every cent!....www.por15.com/
great work !
You need to learn how to vacuum impregnate the cast iron with silicon or some other wear resistance substance like slick 50.
Edward Mitchell what would he be applying this to?
To the cast iron parts where they wear or that is to say have wear points. This is done to engines so that the material doesn't rust out or seize up. Here is a pdf file that explains why this is a good idea: www.sebestasro.cz/cz/get.php?id=496
I worked on internal,external, surface and slideway grinders for 43 years and never got away with not dressing grinding wheels.
nice grinder.
Try some Evapo-Rust on it :) Works wonders.
Coolant helps
Hey there I need to know how to get my od grinder to return to the reference point. Alarm #3023. Help please. Lol
Self repairing machinery, pretty cool.
It will only self-repair if the ways are flat. If they are not, no amount of grinding the table or chuck can save the thing. If ways are worn, then the only way to get it do flat again is to scrape the ways properly.
I guess grinding the angle plate didn't make the cut.
I bet ABom79 will like your shirt!
Taking too large a cut on that surface grinder. That’s first year apprenticeship knowledge!
That's why you don't clamp these things down without a sufficient layer of grease in between the surfaces
"There is nothing about this in the manual...well, i don´t have the manual for this machine" That could be the reason for it not being mentioned :D
Wow!!!!
wow gack attack but a job well done in the end:) 1
That abom quote.. haha
John, are you hiring? I'm a machine design engineer in Chicago.
I think you've been a bad influence. I'm now lapping stuff in. Have an aluminum disk that I've lapped in on a mirror and now I have two steel disks that I'm lapping into each other. There is something about making things exactly so that is addicting to those who have that quirk. I don't think I'll ever have a surface grinder but have a mirror and plenty of sand paper.
Is a mirror really that flat?
Now that I think about it, if you look at a reflection of lines, or a matrix of lines, you can easily see if it is flat. But does the surface of the mirror or is it the rear, silver paint on the rear of the panel makes the reflection flat?
Hmmm.. Anybody knows, guys?
I'm pretty sure it isn't as flat as that nice surface grinder is but it sure is one heck of a lot less money. I'm thinking about taking two 1" pieces of steel and lapping those together and that does make them pretty flat if you do it right.
I've ground and coated a fair number of optical surfaces and there is no such thing as "Flat" only approximations. Even a very good approximation of a flat surface will change depending on how its supported, no matter how thick or sturdy it may appear.
Tom Lipton has some videos where he investigates and performs a few lapping procedures. Interesting stuff. Check them out.
I understand what you're saying about "no such thing as flat". Life is full of these little things we have to decide on if it's good enough for what we're doing. I know I'm not making it "flat" just flat enough. I can see in my minds eye the roughness of a mirrors surface and the horrible amount of flex that thing goes through just with a mild temperature change. But it does what I need of it. Oh, btw, I keep it turned to the wall, that fat guy keeps showing up the same time I do. Damn untrustworthy NOT flat mirror.
does the book have a passage about deadly sins? thou shalt not borrow my tools etc?
the reference down under .. :D hmm this grinding thing .. both surfaces should have been scraped.. ! :D but lets see how it goes... you can do that.. Seen you at a course doing scraping with that old fat guy. :D ... both Keith and Abom was there too.. :D
Did you bother to watch this video? Richard King was there in John's shop instructing a class.
lol.. I know. The king was there! :D
Loaded wheels can get hot enough to explode!
Really close bessell
Lol .0002 dosent really matter unless ur doing some wild micro grinding
Good luck in your career with an angle grinder then. Day in day out, producing parts that have that 0.0002" as the whole tolerance for thickness, meaning that if it doesnt grind flat, the part is already out of tolerance.
Doubt it
John, when you say "a tenth", a tenth of what?
Is it 0.10?
0.01?
0.001?
0.0001?
You say something is good because it only has a deviation of a tenth. Then in another sentence you say it's bad because it is a tenth either high or low.
Please clarify which tenth a 0.1" is enough to feel through a work boot with your foot.
A 0.01" is OK for foundry work.
0.001" is getting close to close enough, but I think the tenth you are meaning is 0.0001 or less. Is that correct ?
It's typical shop terminology. It's a lot easier to say, "a tenth," than it is to say, "one tenthousandth of an inch."
longcaster tenths in machining is a tenth of a thousandth, or 0.0001". Virtually all of machining jargon and shop-speak is in "thou" (1/1000") or "tenths" (1/10000")
longcaster in machining .0001 is a tenth .001 is a thousandth .010 is ten thousandths and .100 is one hundred thousandths
Aside from the replies, to answer your question yes you're correct. It's o.ooo1
Thanks. Cause getting something to 0.1 ain't doing so good with a machine.
Parallelism*
👨🔬🔬👍🐨🗯
John your fault. sorry but rust under plate??? You are fired.. sorry.
One thing I find interesting about rebuilding and calibrating a surface grinder, is that you can use the machine to heal itself! I don't know of another situation like this. Good luck with future adjustments Your positive attitude will prevail.