I use this tip all the time now to find center of a hole in my mill. Drives my lead man nuts! lol. I still double check it with my indicator, just to assure him that I'm still using one, but this tip has never failed to put me within a tenth or two of dead center, and quickly! Thanks for this video!
I am a anesthesia provider and hadn't developed the skill set or took any shop classes back in school. Between your videos and a few books I am rapidly advancing due to your instruction. Simple clear and to the point. Your a very good instructor. Many Thanks
Very useful video. Learned CNC on a Haas minimill using a probe for work offsets, but I recently learned how to use an edgefinder and now see how much better it is. This video just made all of my projects a little easier since I can now center my programs on an existing hole on the part.
+Alan Hunt Thanks Allan, it's good to hear you got some value out of the video. Be sure to keep your edge finder cleaned an lubricated. They don't work near as well when they start getting sticky. Tom
Probes on the Hass are amazing. I would never use a d edge finder if the machine has a probe. Just me tho. I don't sweep hole with an indicator unless the hole is to small for the probe tip. Always good to know how to use other ways but the probes are one of the best pieces of advancement to cnc milling.
Haha what I find amazing is the amount of people telling you that this is wrong or not accurate. You people have obviously not been taught or tried, for 99% of machine work this is spot on. The other who moan on about clocking it but have no clue about the maths lol keep going your doing great.
@@TomsTechniques it's because it is deceptively simple. Go one way get a size plus error go the other way get a size + error. Because any errors are polar opposites they cancel each other out. Or another way is what it is half of an "untrue" measure on each radius which is the same midpoint at y=0 or when y = +1 or -1. I.e. the chord of a circle
I use a manual mill without a digital read out and use a taper dropped down into the hole and move the bed back and forward front to back with "blue" takes a bit of time but works for me. I make parts for motorcycles like the bushings to convert to single sided swing arms. All have worked and the people have always been happy.I have never used digital but might try it the next time round.
This is a cool tip. I'm guessing theres no concern where exactly you touch off because when you travel across the axis to touch off on the other side, the midpoint is the same regardless of how close/far away from center you are.
I'm impressed! First a question. When you say 2 tenth off, does that mean 2 tenth of a thou(sands)🤔 I'm not used to imperial measures 😐 Afterwords I speculate whether in theory you ought to switch rotational direction on the spindle, when touching of on the far sides and near sides of the center due to the curvature of the periphery. I know it's _theory_ only and your comparison between incremental and absolute measurements says it all. Your comment about "way off center" indicates that when you are way off center, the curvature of the periphery, means more than when you are close to the center?
Just the opposite. It will center as it approaches an edge and then jump to the side when half the diameter of the tip from the edge. The tip on this edge finder is .200" diameter, so at .100" from the edge, it will jump to the side. Then you just move .100" to center on the edge and zero your dials or DRO. The pointed ones are used to find center punch marks. You put the point in a center mark and adjust the location until the diameter at the split line mics the same as the shank.
Heck yeah, good idea, I have never seen anybody do that before, that's a simple & fast way to indicate a hole!!!! They never showed us that in high school shop class!! lol
Your subscribers should also be aware that when it comes time to buy an edge finder, don't go cheap with a Chinese set, but rather buy a Starret. There are plenty of tools to save money on, that don't require the Starrett name, but on an edge finder or wiggler, they earn their keep. Not only that, but I've had my Starret edge finder for 23 years and I paid a whopping $12.00 for it. Funny thing is, I've been running manual equipment and CNC mills and lathes for about 30 years, but never considered using my edge finder for hole locations. But, when my Blake Coaxial indicator just went tits up, I can't afford to shell out $400.00 at the moment to replace it. You're the first one I've seen that actually documents how close this technique will get you to center, which was my hesitation in using it for the purpose. On actual edge-find work on a CNC, I've been able to be within .0001-.0002" with my Starret, but never tested the hole theory. Well done.
+GrizzlyMtn I definitely agree with you about not cheaping out on the edgefinder. There are plenty of cases where Chinese imports are acceptable, such as parallels, shop grade gauge blocks and pin gauges (providing you verify their accuracy), but tools like micrometers, digital calipers, indicators and edgefinders should be the best you can afford and not made in China. There are plenty of videos on YT showing how bad this Chinese stuff really is, especially the digital caliper knockoffs. BTW, I don't even use my co-ax indicator any more. Its much quicker to just use the edgefinder and just as accurate. Tom
Surprisingly enough, I've had pretty good results with Chinese mics and calipers. Calipers by their very nature, aren't exactly precision instruments, regardless of the name brand, so I don't mind spending $20.00, rather than $200.00 on a set. With that said, my go-to set of 0-1 mics are an old Brazilian made pair from Mitutoya. Most folks have never seen them made anywhere but Japan. I've used several sets of Chinese mics and went through 6 month calibrations on all of them. They never missed a beat, but the ergos on most lack a lot to be desired. The quality that Starret puts into their final finish on edge finders and wigglers is worth the extra dollar or two you spend over the imports though. Those surfaces have to be extremely smooth and precision and it's quite apparent that the Chinese have not got that figured out yet.
+GrizzlyMtn The problem with the Chinese stuff is a lack of consistency. The same product can be good one time but garbage the next. If you have the ability to calibrate the Chinese mics then you are ahead of the game. The digital caliper knockoffs often have poor battery life compared to Mitutoyo. Mine stay on 24/7 and the batteries last for years. I've always been partial to Etalon mics. The Asian import stuff, including Mitutoyo has always felt too springy in the frame for me. That's not to say they don't measure accurately, just that they don't feel as good. Tom
You're right on the digital calipers. I've used a variety and the Mitutoyo is the best, hands-down. If I buy the cheap Chinese calipers, it's always dial, rather than digital. They work fairly well and it has allowed me to have several sets in the shop to share with employees in different departments. If they get dropped or broke, you're not out much. Never handled the Etalon mics, but my first set was a Polish-made 1-3" that I got through MSC. Dollar-for-dollar, they were the best I've had so far and very comfy to use. Extremely precision and smooth. Some 25 years ago they were a good bargain, but they've decided to price themselves right up with the rest of the spendy brands. Back when I was single and without kids, I found myself spending most of my paychecks on tools. Now days, I've acquired nearly all I'll ever need and then some, just ask my wife...:)
doesn't have to be Starrett edge finder. Could be Brown & Sharpe, Mitutoyo. In fact Starrett has been cheaping out on a lot of stuff nowadays, claiming "they can't compete, yada yada " My response to Starrett is "Oh REALLY?? You can't, huh ?? How does B&S and Mitutoyo manage then ????" Good example: current new Starrett 6" analog dial calipers --- drop them and you asking for trouble, not to mention plastic dial bezel adjusting ring (which likes to crack).....is B&S like that? NOPE!! Is Mitutoyo ??? NOPE! Just my two cents, been machining for 15 years. I wouldn't recommend buying anything Starrett if new ....only the old stuff...particularly that which says on the side L. S. Starrett, That's the GOOD STUFF !!! (did you notice the DON"T PUT "L. S. Starrett" on anything nowadays!!). I stopped buying (anything) brand new starrett after my 6" analog dial calipers went to shit after just 10 months in service at a shop! Here's another one: NEVER buy a dial test indicator by Starrett. Buy: Brown & Sharp "Bestest" --- just ask the folks at Long Island Indicator how the two compare (they repair gages and instruments; and they are Swiss, BTW) -- think about that for a while.
IF the tables trammed close and you set the y first... i think maybe .1 or close on the dial . If the mill has an eliminator... Billy T you can do this~
I know this is old comment, but maybe someone will find this useful: You can very well do it without a DRO, what you need is a dial indicator with a magnet, so that you can read the actual movement of the table. That will take care of the backlash pretty well. Of course, you can pick a hole with max dia of (total indicator travel + edge finder tip diameter) at most, but this takes care of most what you'll meet in a home shop...
Good information! Could you hypothetically use the same method on a CNC Lathe to zero out a drill collet? I may have to try, It would be 20 times easier and quicker then using an indicator.
So basically your saying that the bobin on the bottom will centre when it has hit the furthest point away from the centre is that correct? I have an edge finder with a point on one end. Can you do a video with the correct use of the point?
Question: when you “eyeball” approximate center and run back to “y” axis backside, if you are off ( in the “x” direction) by a couple millimeters you will prematurely hit your stop as you encounter the arc of the circle. Would running back and forth on the “x” axis a few millimeters get you more accurate in your position?
I've tried purposely offsetting the X axis to see what would happen and surprisingly, it had vey little effect on the precision of the center location. Obviously, the farther off center, and possibly the smaller the hole, the more chance for error, but anywhere close works fine. It would be interesring to graph the results.
A diameter line midpoint is your zero, imagine a line below or above that running parallel half of that length still gives the same midpoint, even though the line length has changed due to being off centre. So in essence what ever way your measuring make sure the other direction is at the same value and does not deviate, then your midpoints are all the same.
Not very because the center would bear on the edge of the hole rather than the bore. It's never good practice to work from a sharp corner like that. Tom
The pointy end is actually used for locating a center punch mark, not a hole. The idea is to place the point into the punch mark and then adjust the table until the offset is minimized. You can get close by feeling the offset with your fingers, or use a micrometer. I wouldn't suggest using the conical point for critical holes because you would be locating off the edge of the hole, not the bore. For small holes, just put a pin gauge in them and locate off of that with the edge finder of an indicator. Tom
beepcode I would not recommend doing that, because you would be locating off of a sharp corner instead of a face. The least bit of a burr would throw off the reading. Tom
You know, I've been messing about with machine tools (as a rank amateur) for about 6 years now, and never figured out what the conical tip on a Starrett 827B is for. And it certainly isn't that I haven't looked for this information, on the Web and elsewhere. So thank you! I think a short video demonstrating the use of this little frammis -- and why it shouldn't be used for locating holes and similar features -- would be really useful!
Great video. Can you explain why there's a 2 tenths difference between absolute and incremental? I don't fully understand the difference between the two. Thanks.
Thanks Jason. Absolute refers to a fixed reference point on the part, such as one corner or the center. Once that is set, you can move to the center point of a feature on the part such as a pocket or hole pattern, switch to incremental mode and zero out the DRO without disturbing the absolute setting. That way if there is more than one feature on a part, you can refer back to the absolute reference point for each of them. The .0002" difference in the reading is because the DRO reads in .0002" increments and it's likely sitting somewhere in the middle. Tom
You said 2 tenths though. Maybe that's how its said on digitized equipment when you know the scale or resolution but .0002 is 20 thousandths right? That being the case even on precision work no bad at all!
Without a DRO you need to take into account the amount of play in the leadscrew, usually .010"-.015". Every time you change direction, you need to add that amount to the reading. If you find the center using an edge finder you can see exactly how much play there is in the screws and split the difference when you zero the dials. Tom
When I first started doing this, I thought the same thing and did the centering process twice to compensate. But as it turns out, unless you are grossly off center, it just doesn't matter. Tom
@@TomsTechniques lol, I get all kinds of speeds depending on who I ask. I was taught to use 1400 when I started. I heard people say anything from 750 to 2500 rpm. 1400 always works for me. But it's amazing how many different answers you'll get when asking.
Turns out it doesn't matter. I've purposely offset the edge finder and it made no noticeable difference in the precision. Of course it has to be somewhere near the center line, but it doesn't have to be right on.
If only you could get an electronic edge finder for most hobbyist machines. Hobbyists usually use ER11 collets and work on non-conductive materials. These are 12 or 16 or 20mm ..that would simplify so many things.
i put in a fixed counter center from a lathe and takes me about 10 seconds or less to find the center =). hole has to be smaller then the counter center though.
Yeah, mine is pretty much an expensive paper weight as well. I had on planned getting back to making videos, but life threw me a hell of a curve ball and took one of my sons. I'll get back to it eventually.
Agree, Yes Two tenths of a thou......A typical machinist usually uses .001 as the reference unit. For example: we don't say "Point four" but rather "Four hundred" (.4)....
+David Rector One of the most difficult things to understand for a novice is that statement as applied to a toleranced dimension on a drawing. It is simply not possible to machine a part to an exact dimension, so all dimensions on drawings have tolerances associated with them. For instance, if a .500" dimension has a tolerance of ± .005", an acceptable range for that dimension is from .495" to .505". In other words, any dimension within that range is equally acceptable. So you don't have to waste time and energy machining a part to "exactly" .500" if it has that tolerance on it. Anything within that range is good to go. Tom
One thing I took from this was that the edge finder doesn't have to be centered in the X direction to get the Y center. Well, as long as the hole is round. Until I heard the "doesn't have to be exact" comment, I had the not given it enough thought and would have assumed that the center in one dimension was needed to be able to find the center in the other. Thanks for this video and the other advice about getting within tolerance. I watched your other videos and those were very useful too.
i don't know why people say tis is great, special rotary center tools are made for tis holes, an edgefinder is made for edges, not for a radius, don't misunderstood me, it's posible, but it takes time and it isn't as accurate as you think.
Easy peasy maybe, but not reliable. Center finders are intended to be used on a center punch mark or scribed line. Using then on a hole means they are bearing on the theoretical sharp corner, not the sides like an edge finder, a no no in the machining world.
Your example in the picture looked like a freshly reamed or nicely drilled crisp edged hole. If it's a bolt hole to be treaded with some tolerance, I say go for it. If it's tight like a steel alignment pin...maybe not.
Lol, practice? I think I pretty much have it figured out by now. Try the technique. I think you will be surprised at how well it works, if you have a mill that is. Tom
You weren't paying attention. I bored the hole with the readout centered to show how well the edgefinder works to find the center of the hole. It wouldn't be a very good tip if it ended up off center.
@@TomsTechniques I apologize. I wasn't paying as much atttention as I thought. I did the math just for fun. Your technique works. I apologize for jumping to a conclusion before I thoroughly understood the process.
Don't be so narrow minded Albert. This is a quick way to find the center of a hole without, in the case of a hobbyist, having to purchase an expensive dial indicator. Even so, it is surprisingly precise and definitely faster than indicating. I save time by using this technique in my shop quite often and don't feel stupid at all.
That is actually not true. In the video I bored a hole, zeroed out the DRO, then picked up the same hole with the edge finder with much better accuracy than .001". Try it and verify with an indicator if you doubt the result.
If you are such an expert, perhaps you should try making a few videos yourself and enlighten us. But then again, it's a whole lot easier to just bitch about the efforts of others.
Ok fine. But you really should describe the basic arithmetic to use if your DRO does NOT have a Mid-Point function. You're really just showing how your DRO functions.
This technique won't work on a mill without a DRO because there would be no way to accurately compensate for the backlash in the leadscrew. I often show how to do operations without a DRO in my videos, but this is not one of them. Tom
+pbrubaker Find one side of the hole and zero the axis. Find the other side and divide by two. Move to that point and zero again. Repeat for the other axis.
@@TomsTechniques Then why don't you do the video again and check it with an indicator at the end of the video when you are done and prove out your method. No proof this works.
If you actually watched the video, you might notice that the hole I am working with was bored and the DRO zeroed out. Indicating it would be redundant.
I wouldn't exactly call pushing a midpoint button on the DRO math, but you are certainly welcome to use whatever method you like. That's the nice thing about machining, there are a lot of different ways to accomplish the same thing. Tom
I guess it depends on how accurate you need to be. Center drilling and then drilling and reaming I would say could get you to .001 accuracy between holes. When I really wanted to get as accurate as I could I used to center drill then drill and then ream with a slightly smaller end mill than the reamer. Then I would chock that reamer up short. Also I would put the center drill in a collet, NOT in a drill chuck. Any unseeable wobble could throw you off a couple thou in my opinion. And if the top edge of the hole needed to be perfect I would either start the reamer by hand with the machine out of gear and then start it in gear with the reamer already down into the hole about 1/4 inch. OR flip the block over and ream it from the back.
You're a champ! It's people like you that show just what a great educational tool youtube can be. Thank you very much for posting your videos.
+Alan Adams
Thanks for watching!
I use this tip all the time now to find center of a hole in my mill. Drives my lead man nuts! lol. I still double check it with my indicator, just to assure him that I'm still using one, but this tip has never failed to put me within a tenth or two of dead center, and quickly! Thanks for this video!
I've verified it with an indicator as well. It's scary how well it works.
Tom
I am a anesthesia provider and hadn't developed the skill set or took any shop classes back in school. Between your videos and a few books I am rapidly advancing due to your instruction. Simple clear and to the point. Your a very good instructor. Many Thanks
Thanks Adrain.
Tom - you are the BEST! I always find your You Tube vids when trying to learn a "basic" operation. THANKS!
Very useful video. Learned CNC on a Haas minimill using a probe for work offsets, but I recently learned how to use an edgefinder and now see how much better it is. This video just made all of my projects a little easier since I can now center my programs on an existing hole on the part.
+Alan Hunt
Thanks Allan, it's good to hear you got some value out of the video. Be sure to keep your edge finder cleaned an lubricated. They don't work near as well when they start getting sticky.
Tom
Probes on the Hass are amazing. I would never use a d edge finder if the machine has a probe. Just me tho. I don't sweep hole with an indicator unless the hole is to small for the probe tip. Always good to know how to use other ways but the probes are one of the best pieces of advancement to cnc milling.
Haha what I find amazing is the amount of people telling you that this is wrong or not accurate. You people have obviously not been taught or tried, for 99% of machine work this is spot on. The other who moan on about clocking it but have no clue about the maths lol keep going your doing great.
Lol, it's always fun to think outside the box. I'm still astounded at precision of this technique.
@@TomsTechniques it's because it is deceptively simple. Go one way get a size plus error go the other way get a size + error. Because any errors are polar opposites they cancel each other out. Or another way is what it is half of an "untrue" measure on each radius which is the same midpoint at y=0 or when y = +1 or -1. I.e. the chord of a circle
Pin gauges are also handy for finding centers on a Bridgeport.
I use a manual mill without a digital read out and use a taper dropped down into the hole and move the bed back and forward front to back with "blue" takes a bit of time but works for me. I make parts for motorcycles like the bushings to convert to single sided swing arms. All have worked and the people have always been happy.I have never used digital but might try it the next time round.
This is a cool tip. I'm guessing theres no concern where exactly you touch off because when you travel across the axis to touch off on the other side, the midpoint is the same regardless of how close/far away from center you are.
I've tried doing it with the edge finder off center and it really doesn't make any difference until you get way off center.
I'm impressed!
First a question.
When you say 2 tenth off, does that mean 2 tenth of a thou(sands)🤔
I'm not used to imperial measures 😐
Afterwords I speculate whether in theory you ought to switch rotational direction on the spindle, when touching of on the far sides and near sides of the center due to the curvature of the periphery.
I know it's _theory_ only and your comparison between incremental and absolute measurements says it all.
Your comment about "way off center" indicates that when you are way off center, the curvature of the periphery, means more than when you are close to the center?
Thank you so much Tom. I just used this technique and it works flawlessly.
Thanks. It's one of my favorite contrary machining practices. :)
Thanks for showing how to do this, cheers from Australia !
Thank You Very Much For Sharing Your Knowledge.
God Bless
Mike T.
Just the opposite. It will center as it approaches an edge and then jump to the side when half the diameter of the tip from the edge. The tip on this edge finder is .200" diameter, so at .100" from the edge, it will jump to the side. Then you just move .100" to center on the edge and zero your dials or DRO.
The pointed ones are used to find center punch marks. You put the point in a center mark and adjust the location until the diameter at the split line mics the same as the shank.
Heck yeah, good idea, I have never seen anybody do that before, that's a simple & fast way to indicate a hole!!!! They never showed us that in high school shop class!! lol
I'm learning so much here, i'm gonna go back and ask my boss for a raise!!
Your subscribers should also be aware that when it comes time to buy an edge finder, don't go cheap with a Chinese set, but rather buy a Starret.
There are plenty of tools to save money on, that don't require the Starrett name, but on an edge finder or wiggler, they earn their keep. Not only that, but I've had my Starret edge finder for 23 years and I paid a whopping $12.00 for it.
Funny thing is, I've been running manual equipment and CNC mills and lathes for about 30 years, but never considered using my edge finder for hole locations. But, when my Blake Coaxial indicator just went tits up, I can't afford to shell out $400.00 at the moment to replace it.
You're the first one I've seen that actually documents how close this technique will get you to center, which was my hesitation in using it for the purpose. On actual edge-find work on a CNC, I've been able to be within .0001-.0002" with my Starret, but never tested the hole theory.
Well done.
+GrizzlyMtn
I definitely agree with you about not cheaping out on the edgefinder. There are plenty of cases where Chinese imports are acceptable, such as parallels, shop grade gauge blocks and pin gauges (providing you verify their accuracy), but tools like micrometers, digital calipers, indicators and edgefinders should be the best you can afford and not made in China. There are plenty of videos on YT showing how bad this Chinese stuff really is, especially the digital caliper knockoffs.
BTW, I don't even use my co-ax indicator any more. Its much quicker to just use the edgefinder and just as accurate.
Tom
Surprisingly enough, I've had pretty good results with Chinese mics and calipers.
Calipers by their very nature, aren't exactly precision instruments, regardless of the name brand, so I don't mind spending $20.00, rather than $200.00 on a set.
With that said, my go-to set of 0-1 mics are an old Brazilian made pair from Mitutoya. Most folks have never seen them made anywhere but Japan.
I've used several sets of Chinese mics and went through 6 month calibrations on all of them. They never missed a beat, but the ergos on most lack a lot to be desired.
The quality that Starret puts into their final finish on edge finders and wigglers is worth the extra dollar or two you spend over the imports though. Those surfaces have to be extremely smooth and precision and it's quite apparent that the Chinese have not got that figured out yet.
+GrizzlyMtn
The problem with the Chinese stuff is a lack of consistency. The same product can be good one time but garbage the next. If you have the ability to calibrate the Chinese mics then you are ahead of the game. The digital caliper knockoffs often have poor battery life compared to Mitutoyo. Mine stay on 24/7 and the batteries last for years.
I've always been partial to Etalon mics. The Asian import stuff, including Mitutoyo has always felt too springy in the frame for me. That's not to say they don't measure accurately, just that they don't feel as good.
Tom
You're right on the digital calipers. I've used a variety and the Mitutoyo is the best, hands-down.
If I buy the cheap Chinese calipers, it's always dial, rather than digital. They work fairly well and it has allowed me to have several sets in the shop to share with employees in different departments. If they get dropped or broke, you're not out much.
Never handled the Etalon mics, but my first set was a Polish-made 1-3" that I got through MSC. Dollar-for-dollar, they were the best I've had so far and very comfy to use. Extremely precision and smooth. Some 25 years ago they were a good bargain, but they've decided to price themselves right up with the rest of the spendy brands.
Back when I was single and without kids, I found myself spending most of my paychecks on tools. Now days, I've acquired nearly all I'll ever need and then some, just ask my wife...:)
doesn't have to be Starrett edge finder. Could be Brown & Sharpe, Mitutoyo. In fact Starrett has been cheaping out on a lot of stuff nowadays, claiming "they can't compete, yada yada " My response to Starrett is "Oh REALLY?? You can't, huh ?? How does B&S and Mitutoyo manage then ????" Good example: current new Starrett 6" analog dial calipers --- drop them and you asking for trouble, not to mention plastic dial bezel adjusting ring (which likes to crack).....is B&S like that? NOPE!! Is Mitutoyo ??? NOPE! Just my two cents, been machining for 15 years. I wouldn't recommend buying anything Starrett if new ....only the old stuff...particularly that which says on the side L. S. Starrett, That's the GOOD STUFF !!! (did you notice the DON"T PUT "L. S. Starrett" on anything nowadays!!). I stopped buying (anything) brand new starrett after my 6" analog dial calipers went to shit after just 10 months in service at a shop!
Here's another one: NEVER buy a dial test indicator by Starrett. Buy: Brown & Sharp "Bestest" --- just ask the folks at Long Island Indicator how the two compare (they repair gages and instruments; and they are Swiss, BTW) -- think about that for a while.
great video Tom, only problem 4 me is I do not a dro. and this task is near impossible without one because your backlash
This technique does work best with a DRO, but if you know how much backlash is in your screws, you can get pretty close with dials too.
Tom
IF the tables trammed close and you set the y first... i think maybe .1 or close on the dial . If the mill has an eliminator... Billy T you can do this~
I know this is old comment, but maybe someone will find this useful:
You can very well do it without a DRO, what you need is a dial indicator with a magnet, so that you can read the actual movement of the table. That will take care of the backlash pretty well. Of course, you can pick a hole with max dia of (total indicator travel + edge finder tip diameter) at most, but this takes care of most what you'll meet in a home shop...
Wow great. I didn't that we can use this tool like this. Thanks, i got new knowledge today.
does the center point come out of these things or is the blunt ended edge finder a separate tool?
This one has a pin on one end and a point on the other. They are not meant to be disassembled.
I am just starting in Milling for fun retirement. Thanks for a great tip.
Thanks for watching. Hope your retirement is a enjoyable as mine.
I hope so to. If you ever get to southern IL come out to Katylynnwinery.com. @@TomsTechniques
Thanks.
It's one of those projects that pays for itself in time savings if you do much rotary table work at all.
Tom
Good information! Could you hypothetically use the same method on a CNC Lathe to zero out a drill collet? I may have to try, It would be 20 times easier and quicker then using an indicator.
Possibly. As long as you can move the edge finder in two axes.
Tom
So basically your saying that the bobin on the bottom will centre when it has hit the furthest point away from the centre is that correct?
I have an edge finder with a point on one end. Can you do a video with the correct use of the point?
Question: when you “eyeball” approximate center and run back to “y” axis backside, if you are off ( in the “x” direction) by a couple millimeters you will prematurely hit your stop as you encounter the arc of the circle. Would running back and forth on the “x” axis a few millimeters get you more accurate in your position?
I've tried purposely offsetting the X axis to see what would happen and surprisingly, it had vey little effect on the precision of the center location. Obviously, the farther off center, and possibly the smaller the hole, the more chance for error, but anywhere close works fine. It would be interesring to graph the results.
A diameter line midpoint is your zero, imagine a line below or above that running parallel half of that length still gives the same midpoint, even though the line length has changed due to being off centre. So in essence what ever way your measuring make sure the other direction is at the same value and does not deviate, then your midpoints are all the same.
Nice video! How accurate would jamming a Live center down the hole be?
Not very because the center would bear on the edge of the hole rather than the bore. It's never good practice to work from a sharp corner like that.
Tom
Don't forget the pointy end of the finder,it works pretty well too. . . .especially on smaller holes.
The pointy end is actually used for locating a center punch mark, not a hole. The idea is to place the point into the punch mark and then adjust the table until the offset is minimized. You can get close by feeling the offset with your fingers, or use a micrometer. I wouldn't suggest using the conical point for critical holes because you would be locating off the edge of the hole, not the bore. For small holes, just put a pin gauge in them and locate off of that with the edge finder of an indicator.
Tom
Toms Techniques
Not Exactly true. The Conical tip is better for finding slot centers and holes and features that are smaller than .200.
beepcode
I would not recommend doing that, because you would be locating off of a sharp corner instead of a face. The least bit of a burr would throw off the reading.
Tom
You know, I've been messing about with machine tools (as a rank amateur) for about 6 years now, and never figured out what the conical tip on a Starrett 827B is for. And it certainly isn't that I haven't looked for this information, on the Web and elsewhere. So thank you!
I think a short video demonstrating the use of this little frammis -- and why it shouldn't be used for locating holes and similar features -- would be really useful!
Great video. Can you explain why there's a 2 tenths difference between absolute and incremental? I don't fully understand the difference between the two. Thanks.
Thanks Jason.
Absolute refers to a fixed reference point on the part, such as one corner or the center. Once that is set, you can move to the center point of a feature on the part such as a pocket or hole pattern, switch to incremental mode and zero out the DRO without disturbing the absolute setting. That way if there is more than one feature on a part, you can refer back to the absolute reference point for each of them.
The .0002" difference in the reading is because the DRO reads in .0002" increments and it's likely sitting somewhere in the middle.
Tom
Makes sense now, thanks.
You said 2 tenths though. Maybe that's how its said on digitized equipment when you know the scale or resolution but .0002 is 20 thousandths right? That being the case even on precision work no bad at all!
ww5rm No, 0.0002” is 2 ten-thousandths of an inch. Twenty thousandths is 0.020”
How do you account for backlash?
Without a DRO you need to take into account the amount of play in the leadscrew, usually .010"-.015". Every time you change direction, you need to add that amount to the reading. If you find the center using an edge finder you can see exactly how much play there is in the screws and split the difference when you zero the dials.
Tom
Thank you sir. I learned a lot from your videos. I hope if you fucos more on gears. ( all kind of gears on milling machine) thank you again
when you touch say in x direction how do you know if you are moving on the y center and not off a bit?
When I first started doing this, I thought the same thing and did the centering process twice to compensate. But as it turns out, unless you are grossly off center, it just doesn't matter.
Tom
Thanks
Old Bob
I do this every day on the overhead comparator at work, but I never thought about using an edgefinder to do the Sam thing.
What spindle spedd do you run your edge finder at?
Lol. Pretty much whatever the mill is set at when I use it. Doesn't seem to make any difference, other than how hard it kicks out.
@@TomsTechniques lol, I get all kinds of speeds depending on who I ask. I was taught to use 1400 when I started. I heard people say anything from 750 to 2500 rpm. 1400 always works for me. But it's amazing how many different answers you'll get when asking.
Hi Tom, I don`t quite understand what you mean by backlash?
Dumb question. When you started on the Y Axis...how do you know your edgefinder is hitting the deepest portion of the hole?
Turns out it doesn't matter. I've purposely offset the edge finder and it made no noticeable difference in the precision. Of course it has to be somewhere near the center line, but it doesn't have to be right on.
How to cutting square thread with lathe & calculation.I thank you.
You sir are a saint
Personally I’d use a clock dial indicator on a hole and edge finder on the side of the material ,I use both every day
This is just another of many methods to consider.
If only you could get an electronic edge finder for most hobbyist machines.
Hobbyists usually use ER11 collets and work on non-conductive materials.
These are 12 or 16 or 20mm
..that would simplify so many things.
Marcus Wolschon you can buy ekectric edge finders
i put in a fixed counter center from a lathe and takes me about 10 seconds or less to find the center =).
hole has to be smaller then the counter center though.
How?
+noshortnamesleft atall
It sounds like he is putting a center in the spindle and "finding" the hole by feel. Fast maybe, but not very accurate.
Tom
+noshortnamesleft atall and also works in a 4mm hole, accuracy is very good.
Thanks for the info, but what's up with your mill? It sounds like it's going to blow up any second.
Good ear. The bronze sleeve in the variable speed pulley had worn along with the key. I made a new sleeve and key and it's all better now.
Tom
Anyone want to buy my coaxial indicator? Thanks for the great video Tom. I pray you are ok...miss your wonderful instruction
Yeah, mine is pretty much an expensive paper weight as well. I had on planned getting back to making videos, but life threw me a hell of a curve ball and took one of my sons. I'll get back to it eventually.
Toms Techniques oh no! I’m so sorry Tom. I’ll remember you and your family in my prayers
Within 2 tenth`s or two 1/tenth`s ?
Two ten thousandths of an inch (.0002).
Agree, Yes Two tenths of a thou......A typical machinist usually uses .001 as the reference unit. For example: we don't say "Point four" but rather "Four hundred" (.4)....
"Doesn't have to be exact" - I'm a complete novice and that was the bit of information I was looking for.
+David Rector
One of the most difficult things to understand for a novice is that statement as applied to a toleranced dimension on a drawing. It is simply not possible to machine a part to an exact dimension, so all dimensions on drawings have tolerances associated with them. For instance, if a .500" dimension has a tolerance of ± .005", an acceptable range for that dimension is from .495" to .505". In other words, any dimension within that range is equally acceptable. So you don't have to waste time and energy machining a part to "exactly" .500" if it has that tolerance on it. Anything within that range is good to go.
Tom
One thing I took from this was that the edge finder doesn't have to be centered in the X direction to get the Y center. Well, as long as the hole is round. Until I heard the "doesn't have to be exact" comment, I had the not given it enough thought and would have assumed that the center in one dimension was needed to be able to find the center in the other. Thanks for this video and the other advice about getting within tolerance. I watched your other videos and those were very useful too.
Very usefull! thanks Tom
Pelle B
Thanks for watching.
Lot more simple than using a test indicator
2 holes x y black center video link send me...
I'll be attempting this shortly with an indicator instead of a DRO :)
This worked beautifully!
i don't know why people say tis is great, special rotary center tools are made for tis holes, an edgefinder is made for edges, not for a radius, don't misunderstood me, it's posible, but it takes time and it isn't as accurate as you think.
Use a pointed center finder and it verifies X and Y at the same time...easy peasy.
Easy peasy maybe, but not reliable. Center finders are intended to be used on a center punch mark or scribed line. Using then on a hole means they are bearing on the theoretical sharp corner, not the sides like an edge finder, a no no in the machining world.
Your example in the picture looked like a freshly reamed or nicely drilled crisp edged hole. If it's a bolt hole to be treaded with some tolerance, I say go for it. If it's tight like a steel alignment pin...maybe not.
Right. If you don't need the precision, then use whatever is quickest.
Practice more with an indicator. Its faster and more accurate by alot
Lol, practice? I think I pretty much have it figured out by now. Try the technique. I think you will be surprised at how well it works, if you have a mill that is.
Tom
More accurate than 2 tenths on a mill...
If you need more accurately holes or whatever.... you better in a climate controlled shop with a jig grinder
Feels like you're going to slip with the camera sitting on the machine.
Why don't you use that mill to build a TRIPOD!
Thanks for the suggestion, but some things just can't be shown with a stationary CAMERA!
Wish I had DRO on mine
Very cool
Thanks for watching.
Excellent ideal
+Mert Silliker
Thanks
What you have done is guaranteed that you will end up exactly in the center of where you started. That is all.
You weren't paying attention. I bored the hole with the readout centered to show how well the edgefinder works to find the center of the hole. It wouldn't be a very good tip if it ended up off center.
@@TomsTechniques I apologize. I wasn't paying as much atttention as I thought. I did the math just for fun. Your technique works. I apologize for jumping to a conclusion before I thoroughly understood the process.
Don’t mislead people, they’re going to look stupid if they do this at a shop. Use the right tool, use a dial test indicator
Don't be so narrow minded Albert. This is a quick way to find the center of a hole without, in the case of a hobbyist, having to purchase an expensive dial indicator. Even so, it is surprisingly precise and definitely faster than indicating. I save time by using this technique in my shop quite often and don't feel stupid at all.
Thanks.
good tip ty
Excellent. Thank you for posting :-)
Not very accurate way if your tolerance for the center is .001 or less
That is actually not true. In the video I bored a hole, zeroed out the DRO, then picked up the same hole with the edge finder with much better accuracy than .001". Try it and verify with an indicator if you doubt the result.
Just so you know im top level machinist and programmer. I know how and edge finder works.
Got it. Thanks.
Thanks...!!!
Just twitched the camera. My head spin.That you guys aren't making good quality just to give you likes
If you are such an expert, perhaps you should try making a few videos yourself and enlighten us. But then again, it's a whole lot easier to just bitch about the efforts of others.
Ok fine. But you really should describe the basic arithmetic to use if your DRO does NOT have a Mid-Point function. You're really just showing how your DRO functions.
This technique won't work on a mill without a DRO because there would be no way to accurately compensate for the backlash in the leadscrew. I often show how to do operations without a DRO in my videos, but this is not one of them.
Tom
Toms Techniques
I did not suggest to do this without a readout. I Commented that you should Explain the core method here.
beepcode
Sorry, my mistake. The thought never occurred to me since I've never seen a DRO without a midpoint function.
Tom
+pbrubaker
Find one side of the hole and zero the axis. Find the other side and divide by two. Move to that point and zero again. Repeat for the other axis.
Toms Techniques ,👍
That will get ya close. .0002???? maybe if your lucky. about .001 most of the time
All day long. Try cleaning and lubing your edgefinder and it will be a lot more repeatable.
Tom
I can dial it in faster.
But not cooler.
This is completely wrong. It will kick out above center not being on a straight edge.
Apparently not when the finder is anywhere near the center of the hole. This is a technique I use all the time and it works very well.
@@TomsTechniques Then why don't you do the video again and check it with an indicator at the end of the video when you are done and prove out your method. No proof this works.
If you actually watched the video, you might notice that the hole I am working with was bored and the DRO zeroed out. Indicating it would be redundant.
@@TomsTechniques Too lazy to show it with an indicator then. Ok, doesn't work.
I would use an indicator ! This look like a lot of wasting time .
I'll race you. ;)
Stephen Colbert and the late show
Just use an indicator PLEASE. No math involved.
I wouldn't exactly call pushing a midpoint button on the DRO math, but you are certainly welcome to use whatever method you like. That's the nice thing about machining, there are a lot of different ways to accomplish the same thing.
Tom
Tom...you are a patient man. Finding a distance and dividing by two is barely math as well. Thanks for the enjoyable videos.
I am a patient man. :)
Thanks for watching.
Tom
I guess it depends on how accurate you need to be. Center drilling and then drilling and reaming I would say could get you to .001 accuracy between holes. When I really wanted to get as accurate as I could I used to center drill then drill and then ream with a slightly smaller end mill than the reamer. Then I would chock that reamer up short. Also I would put the center drill in a collet, NOT in a drill chuck. Any unseeable wobble could throw you off a couple thou in my opinion. And if the top edge of the hole needed to be perfect I would either start the reamer by hand with the machine out of gear and then start it in gear with the reamer already down into the hole about 1/4 inch. OR flip the block over and ream it from the back.
Just use a indicator. That will get you close. Gonna have to indicate it anyway. If you didn't in my shop I would fire you immediately.
Lol. You must not run a very successful shop if you waste time indicating points already located with an edge finder.