You the man Keith! That was thoroughly entertaining. I hate math but sat through your explanation without feeling overwhelmed and or bored........Keep up the good work!
Thank you Keith for your time and effort, to not only bring these videos out, but also explain (what to some is a complicated process) simply and through diagrams. Cheers.
Some comments question your methods or suggest a different procedure. There are other ways, perhaps but you got nearly perfect results. I think your methods are just great.
For 80 years, my Great Aunt Sigrid started every day with a mug of black coffee and a glass of Akvavit. She baked her own bread until she was 87 years old. She always said that store bought bread didn't taste right.
Keith, This has to be one of the best videos you’ve ever done. There might be other quicker ways to do the calculations, but this method always works for me. Besides, this is the way I learned it 40 years ago and old habits are hard to break. Keep up the GREAT videos.
Love the auto feed, a pair of machinists learning surface grinding for our shops future. To us if you love math you will love surface grinding. We see you are using air mist we see others using flood coolant so interesting to watch.
Keith - excellent video as always. There was no need to use trig, just a proportion calculation: (10÷10.390)×0.216=0.2078 much simpler and quicker. This works because you have similar triangles, in other words triangles of the same shape, so the ratios of the sides are the same for both triangles.
Absolutely! KISS Principle applies here. Doing the calc using similar triangles takes out the approximation and hence the inaccuracy of the angle calculation
If his surface plate is level as it should be. Using a machinists level would do the job. Especially if the first grind was only to get close as it was in this video.
I was thinking the same thing, but it was fun to get a trig refresher after 50 years. Looks like the cast bar still had some internal tension as it appeared to have twisted some after the machining.
Proportion was what I was thinking while watching and I went and got a calculator which cranked out to be 0.207892 before he got his number. I know that I took it to too many places but in rounding it makes 0.2079. I am wondering if the micrometer would not have been the better choice to start with as Kieth said his calipers are not that accurate. Just thinking. It all worked out well which is the goal.
Despite the nay sayers comments, doing the math is the best way to get everything right on. I might have use the surface plate and a height gauge to get the dimensions for the ends of the gib but really, the way Keith did it works fine for the original set-up. It's a one off piece that needs to be highly accurately made and time isn't really all that important here.
Hmm... I've been trying to figure out a slick lighting solution for my mill...then I see you've got a magnetic flexible arm LED light. I have an extra one of these that came with a sewing machine I bought. Thanks, you've helped me more than you possibly realized and wasn't even directly related to the video!
Also, when using the basic trig functions, I gotta mention SOH CAH TOA, a mnemonic for knowing which trig function goes with which sides of the triangle. (sin = opposite / hypotenuse, cos = adjacent / hypotenuse, tan = opposite / adjacent)
Keith - thanks for the math refresher course. What other subjects do you teach? American History, English Lit, Economics? Sign me up for your next class !!!!
Thanks Keith. I love the detail on the math. I am in the process of restoring a Clausing model 5913. I started myself a You Tube Favorites file on lathe repair and have saved this one to it. I always love to see the resurrection of this old Iron. Thanks for taking time to share the detail of how you did it.
Great video, im just a home layman and the trig is beyond me, but looks like youre on your way to yet another finished piece in the lathe restoration - it will serve you well.
Awesome video Kieth. Great use of trig to solve needed stack up. You are probably aware that standard Gib taper is .250 per foot, so all the measuring of the old gib to determine angle wasn't necessary, but nonetheless was an excellent exercise and provided a great tutorial for viewers to show how an unknown taper can be determined! Kudo's
I quess that ten inch required height could be be calculated also by using relation without any rounding errors from going to angle and coming back... Just simply (10 inch/10,39 inch) x 0.216 inch = 0.2078 inch :) Thanks for the really nice gib video series! I accidentally broke one of my gibs from the lathe so have to somehow repair that someday. This is excellent base for what&how to do.
Hi Keith. Could you use a small machinist’s jack and prop it up under the sine plate, then adjust until level with a Brown & Sharpe (or Starrett) bubble level? Then, once you’ve got that, take it over to the grinder, and mike it in that last little bit? 😏
Keith, enjoyable video. May I suggest while you have the cross slide apart now would be a perfect time to add a couple of oil ports to lube those ways and carve some oil paths in the bible and opposing way. That would make a great video.
First, let me say, great video, as always. I love it when I get notified that you've released a new video. BUT... (and you knew this was coming)... I just have to say that the shape of the gib is not a trapezoid. It is a parallelogram. Please don't flame this comment too hard. Thanks :D
No a trapezoid is not a parallelogram. And a trapezoid is not a parallelogram. A trapezoid is a four sided figure with two parallel sides and two nonparallel side. A parallelogram is a four sided figure with two pairs of parallel sides.
@@jeffschira9685 www.mathsisfun.com/quadrilaterals.html Trapezoids (US) are a class of geometric shapes, including parallelograms, rhombus, rectangles, and square as special cases... but not kites! Yes the most specific answer is parallelogram, but hey...
I think I would have left it long until I fitted it. I would be too afraid by the time I got it right it would be too short again, it only takes a little off the width for those things to travel a long way!
While I have nothing against math and trigonometry, I would suggest a way to bypass the trigonometry steps in this case. As the reference part is longer than the 10 inches of the sine plate base, just mark 10 inches rom one end and measure the thicknesses at the end and at the 10 inch mark. The difference between these two readings is directly the required stack for raising your sine plate for the desired angle..
if you do the turcite trick on that gip.. one of the sides.. you will have no bad wear on any of your parts. and u should have done that also inside at the 30 dgr angle. That would have done a hell of change in wear...
All you needed to do is put two lines on the gib 10" apart and measure the thickness at both lines. Subtract one from the other and that is the height of your shim stack.
So cool Keith, question? Did you account for keeping gib perfectly parallel with direction of grinder? Not sure but seems like that would change the math if it wasn't parallel.
I was thinking the exact same thing. The angle won't be correct if the gib isn't parallel with the direction of travel. For example, if you turn the gib 90 degrees, then there won't be any angle along the long length.
the angle bracket-like piece at the end of the sine plate is up against a flat piece (though small) of the gib, so that should keep it fairly close, and scraping will take care of the rest.
I enjoyed the math - brings back memories of HS trig class. Could the angle grind have been done using the granite surface plate, sweep the old gib with a micrometer, then add blocks to the Sine plate until the mic reads zero end-to-end?
Keith, If the gib has 1/4" per foot taper the 10 inch sine plate should need 0.20833 (+ the 0.100 step). This is within 0.001" of your stack and you will be scraping anyway. Just nit picking I guess. Great job on the video.
Keith, WOW what a great job I see on your new gib.!. One question though, now that you have your tail rest & center rest, will you get the pneumatic tapper attachment working and in stalled.?.!.!.!.
Neat video. One slight issue with the math. You can't get 4 significant digits after the decimal if your measurments were only taken to 3. It would have been correct to round the height to .208. It won't matter much, since the gib doesn't actually have to be accurate to .0001 (or you'd have used a micrometer). Just wondering if you could have gotten just as good a result with a precision level.
Qjuestion: Since you're trying to make the first two faces parallel, How do you assure the workpiece isn't warped by the magchuck as the seating face is only milled "flat"?
I wonder if the stack really should have been slightly different. The measurements you came up with work out to about 0.249 inches per foot. I think it is reasonable to assume the design taper was 0.250" per foot. sin(atan(0.250/12))* 10 = 0.208288, so the stack would be 0.2083. Of course since you tweaked it to match the machine it doesn't really matter.
exellent job on the taper. well now i know how you held the gib to get the angle. you used your new angle sine mag plate lol. nice to have that tool in your arsenal of tooling.
OUTSTANDING math and machining! Unexpected sparks ALWAYS get my attention too, especially when working with electricity. :-) For those who may have difficulty remembering the trig functions, just remember SOH-CAH-TOA which is pronounced "socatoa". (This is the recommendation a medicineman gave to an early Indian who dropped a chainsaw on his toe while cutting wood. Yeah, it sounds dumb but it may help you remember the word.) "SOH" is sine = opposite over hypotenuse, "CAH" is cosine = adjacent over hypotenuse and "TOA" is tangent = opposite over adjacent.
since it's not a variable thing couldn't you just mark 6" on the gib, sweep it with an indicator on a surface plate, then have your thou taper per foot?
Keith, since your pivot and the other end are 10.00 inches apart, why not just measure the fat end of the wedge, and then, measure 10.00 inches away, towards the thin edge? steve
Why not use the short gib as a template and lay the new one on top (opposite small end over large end) on the magnetic vise? That would provide the angle as the old one was ground? I understand the need to know how to calculate it, however in this case you have a template to grind from....
I got the impression that the old gib was worn in the middle. The magnetic forces would have pulled the new one out of true and produced a faulty grind.
The original gib angle wasn't quite right which, along with the fact that it was too thin is the reason for making the new gib. It can be used to get the angles close but once that is done you need to fine tune the angle until it's right on dimension.
I have a question regarding the math there. .2078 over 10" works out to .24936 per foot. I suspect that the actual measurement was .25000 per foot. Do you ever check your measurements to see if they're very nearly a logical number?
Scraping gives a bit of roughness to the surface of the metal so it will hold some oil. If you used just the ground side it could squeeze all the oil out and leave it dry (prone to rust).
If at all possible could we get rid of the red line on the preview screenshot? when i scan my videos, it looks so much liked the viewed completion red line i think i have watched this video before.
Keith, I do not like just mag., on part with no support on ends, and sides. You can get an assortment of desperate mag., blocks, to block your work pc., in, so there is no accidents!!! You can get blocks as required, it's much safer, believe me, I ran a surface grinder........🍁
Hi Keith I really enjoy your videos and look forward to the next installment. I was always taught that you should "wring" the gauge blocks together to get a truly accurate stack.
I was jumpy for the few seconds afterwards, while he was waving his hands around near the work, with the wheel running, and looking at the camera. I was sure we were going to see a finger fed between the wheel and the work.
Great video! I would have liked to see the math the second time, but understand it would have been repetitive and probably boring for many viewers. Thanks.
My father was an engineer, but he couldn't operate a surface grinder because, due to military service, he'd lost the upper register of his hearing, so he couldn't hear the wheel "sing", when it needed dressing.
I remember using one of them in High school, it was great and the teacher always told us to make sure the wheel is clear of the work all along (Test run) and the guard was up too, but the sod forgot to do it his self one day and shot the peace and parts of the wheel out a window that was close to the machine and the bits just missed my self and a friend by inches. Till a few years ago when he passed, every time we saw and talked we never forget that day,. He was one of only 4 teachers from that school that understood my work ethic and loved to teach me.
nothing like a well planned operation working out just like you wanted
You the man Keith! That was thoroughly entertaining. I hate math but sat through your explanation without feeling overwhelmed and or bored........Keep up the good work!
I’m glad to see I’m not the only one who jumps when the wheel unexpectedly makes contact with the work piece.
that was funny lol
luck wasn't a factor. the numbers don't lie. great approach to a tricky problem. great skills.
Thanks Keith for showing us your method for determining the correct angle. Very informative.
Nice work Kieth! Thanks
Thank you Keith for your time and effort, to not only bring these videos out, but also explain (what to some is a complicated process) simply and through diagrams. Cheers.
Some comments question your methods or suggest a different procedure. There are other ways, perhaps but you got nearly perfect results. I think your methods are just great.
This is a fascinating project!
Perfect video for my morning coffe here from a wet and cold Sweden.
For 80 years, my Great Aunt Sigrid started every day with a mug of black coffee and a glass of Akvavit. She baked her own bread until she was 87 years old. She always said that store bought bread didn't taste right.
Excellent video Keith! Thanks
Keith, This has to be one of the best videos you’ve ever done. There might be other quicker ways to do the calculations, but this method always works for me. Besides, this is the way I learned it 40 years ago and old habits are hard to break. Keep up the GREAT videos.
Thanks for sharing , I cannot wait to see this old girl up and running again! Great job Keith! Thank you and may God bless you!
Love the auto feed, a pair of machinists learning surface grinding for our shops future. To us if you love math you will love surface grinding. We see you are using air mist we see others using flood coolant so interesting to watch.
OUTSTANDING WORK MY FRIEND!!
A good lesson illustrating the practicalities involved.
Keith - excellent video as always. There was no need to use trig, just a proportion calculation: (10÷10.390)×0.216=0.2078 much simpler and quicker. This works because you have similar triangles, in other words triangles of the same shape, so the ratios of the sides are the same for both triangles.
Absolutely! KISS Principle applies here. Doing the calc using similar triangles takes out the approximation and hence the inaccuracy of the angle calculation
If his surface plate is level as it should be. Using a machinists level would do the job. Especially if the first grind was only to get close as it was in this video.
I was thinking the same thing, but it was fun to get a trig refresher after 50 years. Looks like the cast bar still had some internal tension as it appeared to have twisted some after the machining.
Proportion was what I was thinking while watching and I went and got a calculator which cranked out to be 0.207892 before he got his number. I know that I took it to too many places but in rounding it makes 0.2079. I am wondering if the micrometer would not have been the better choice to start with as Kieth said his calipers are not that accurate. Just thinking. It all worked out well which is the goal.
@@royreynolds108 Yeah- unless you have a micrometer with ball ends, it is difficult to be 100% accurate on a tapered piece
Blue that puppy up and let’s see how she fits. Great video keep it up
Very nice video and another lesson learned. Thanks for sharing.
Despite the nay sayers comments, doing the math is the best way to get everything right on. I might have use the surface plate and a height gauge to get the dimensions for the ends of the gib but really, the way Keith did it works fine for the original set-up. It's a one off piece that needs to be highly accurately made and time isn't really all that important here.
Thank you Keith
Hmm... I've been trying to figure out a slick lighting solution for my mill...then I see you've got a magnetic flexible arm LED light. I have an extra one of these that came with a sewing machine I bought. Thanks, you've helped me more than you possibly realized and wasn't even directly related to the video!
Also, when using the basic trig functions, I gotta mention SOH CAH TOA, a mnemonic for knowing which trig function goes with which sides of the triangle. (sin = opposite / hypotenuse, cos = adjacent / hypotenuse, tan = opposite / adjacent)
Keith - thanks for the math refresher course. What other subjects do you teach? American History, English Lit, Economics? Sign me up for your next class !!!!
Thanks Keith. I love the detail on the math. I am in the process of restoring a Clausing model 5913. I started myself a You Tube Favorites file on lathe repair and have saved this one to it. I always love to see the resurrection of this old Iron. Thanks for taking time to share the detail of how you did it.
Keith you’re a master of you do
Nice work Keith
this rebuilding series we really be invaluable when i get to this point on my old 16" o series south bend
Great video, im just a home layman and the trig is beyond me, but looks like youre on your way to yet another finished piece in the lathe restoration - it will serve you well.
Outstanding lesson! Thanks, Keith.
Awesome video Kieth. Great use of trig to solve needed stack up. You are probably aware that standard Gib taper is .250 per foot, so all the measuring of the old gib to determine angle wasn't necessary, but nonetheless was an excellent exercise and provided a great tutorial for viewers to show how an unknown taper can be determined! Kudo's
Nice Job Keith - You couldn't ask for a better fit !
Congrats on the progress Keith! Nice job!
Keith, Very Nice gib, Great video thanks for sharing.!.!.!.
I quess that ten inch required height could be be calculated also by using relation without any rounding errors from going to angle and coming back... Just simply (10 inch/10,39 inch) x 0.216 inch = 0.2078 inch :) Thanks for the really nice gib video series! I accidentally broke one of my gibs from the lathe so have to somehow repair that someday. This is excellent base for what&how to do.
Well done Keith!
Lovely job Keith. Proper engineering. Apart from the calculator that is !!!
Great video and a great success as expected. Thanks for the video.
Good morning, Keith! Happy Friday and weekend to you, sir!
Nice work Keith!
ATB, Robin
Nice job Keith!
Steve
GREAT VIDEO !!
Thanks for the video and explanations. Very interesting.
Math....ouch, my head hurts! Excellent video for the mathematical end as well as the machining aspect. Thanks very much.
Very enjoyable to watch, as always 🇬🇧
Really enjoyed that Keith, nice informative video :)
Great Video, Nice Job!!
Excellent work Keith. that should scrape in with not much effort one would think.
Keith nice work.
Jeeeeezzzzzz folks give the man a break. Remember he is still learning........ Little kidding around there. He got it done and it fit!
Very nice!
Hi Keith. Could you use a small machinist’s jack and prop it up under the sine plate, then adjust until level with a Brown & Sharpe (or Starrett) bubble level? Then, once you’ve got that, take it over to the grinder, and mike it in that last little bit? 😏
A fine lesson in trigonometry
Love your work bud, long time sub and viewer, please keep up the great content. =)
THANK YOU...for sharing.
Keith, enjoyable video. May I suggest while you have the cross slide apart now would be a perfect time to add a couple of oil ports to lube those ways and carve some oil paths in the bible and opposing way. That would make a great video.
Very interesting video
First, let me say, great video, as always. I love it when I get notified that you've released a new video. BUT... (and you knew this was coming)... I just have to say that the shape of the gib is not a trapezoid. It is a parallelogram. Please don't flame this comment too hard. Thanks :D
At last someone noticed.
A parallelogram is a trapezoid with two pairs of parallel sides.
No a trapezoid is not a parallelogram. And a trapezoid is not a parallelogram. A trapezoid is a four sided figure with two parallel sides and two nonparallel side. A parallelogram is a four sided figure with two pairs of parallel sides.
@@jeffschira9685 www.mathsisfun.com/quadrilaterals.html Trapezoids (US) are a class of geometric shapes, including parallelograms, rhombus, rectangles, and square as special cases... but not kites!
Yes the most specific answer is parallelogram, but hey...
Jim Korman
That's like saying that a square is a circle with corners.
I think I would have left it long until I fitted it. I would be too afraid by the time I got it right it would be too short again, it only takes a little off the width for those things to travel a long way!
It will be nice to see the first cuts on that lathe it should be really accurate👍
While I have nothing against math and trigonometry, I would suggest a way to bypass the trigonometry steps in this case. As the reference part is longer than the 10 inches of the sine plate base, just mark 10 inches rom one end and measure the thicknesses at the end and at the 10 inch mark. The difference between these two readings is directly the required stack for raising your sine plate for the desired angle..
23:39 "were gonna take it over to the lathe …"
what the hell are you gonna do to that part on a lathe?
"for a test fit"
doh! I'm still laughing :D
if you do the turcite trick on that gip.. one of the sides.. you will have no bad wear on any of your parts. and u should have done that also inside at the 30 dgr angle. That would have done a hell of change in wear...
All you needed to do is put two lines on the gib 10" apart and measure the thickness at both lines. Subtract one from the other and that is the height of your shim stack.
So cool Keith, question? Did you account for keeping gib perfectly parallel with direction of grinder? Not sure but seems like that would change the math if it wasn't parallel.
I probably eyeballed it the best he could, the scrapping will take care of it anyway.
I was thinking the exact same thing. The angle won't be correct if the gib isn't parallel with the direction of travel. For example, if you turn the gib 90 degrees, then there won't be any angle along the long length.
the angle bracket-like piece at the end of the sine plate is up against a flat piece (though small) of the gib, so that should keep it fairly close, and scraping will take care of the rest.
If you do the math you’ll see he’d have to put it on the table really slanted to have any significant error.
I enjoyed the math - brings back memories of HS trig class. Could the angle grind have been done using the granite surface plate, sweep the old gib with a micrometer, then add blocks to the Sine plate until the mic reads zero end-to-end?
Keith, If the gib has 1/4" per foot taper the 10 inch sine plate should need 0.20833 (+ the 0.100 step). This is within 0.001" of your stack and you will be scraping anyway. Just nit picking I guess. Great job on the video.
Keith, WOW what a great job I see on your new gib.!. One question though, now that you have your tail rest & center rest, will you get the pneumatic tapper attachment working and in stalled.?.!.!.!.
Neat video. One slight issue with the math. You can't get 4 significant digits after the decimal if your measurments were only taken to 3. It would have been correct to round the height to .208. It won't matter much, since the gib doesn't actually have to be accurate to .0001 (or you'd have used a micrometer). Just wondering if you could have gotten just as good a result with a precision level.
Its nice showing the math and we all should know how, but there are apps for that.
left side height - right side height = the angle offset at the length of the widget simple geometry no trig needed
👍
Qjuestion:
Since you're trying to make the first two faces parallel,
How do you assure the workpiece isn't warped by the magchuck as the seating face is only milled "flat"?
what did you make that out of the get orange sparks
I wonder if the stack really should have been slightly different.
The measurements you came up with work out to about 0.249 inches per foot.
I think it is reasonable to assume the design taper was 0.250" per foot.
sin(atan(0.250/12))* 10 = 0.208288, so the stack would be 0.2083.
Of course since you tweaked it to match the machine it doesn't really matter.
I think you are correct but with all of the wear and scraping the measurements changed over the years.
...did you ever get the new fence for that magchuck, or is it still the one you made?
Keith, doesn't it make a difference as to where you put the stack of blocks?
Super work Keith!!!
exellent job on the taper. well now i know how you held the gib to get the angle. you used your new angle sine mag plate lol. nice to have that tool in your arsenal of tooling.
Keith had to change his underwear after he made first contact with that gib, LOL
Keith, most folks would have shimmed the old gib. You did it the right way, very nice.
OUTSTANDING math and machining!
Unexpected sparks ALWAYS get my attention too, especially when working with electricity. :-)
For those who may have difficulty remembering the trig functions, just remember SOH-CAH-TOA which is pronounced "socatoa". (This is the recommendation a medicineman gave to an early Indian who dropped a chainsaw on his toe while cutting wood. Yeah, it sounds dumb but it may help you remember the word.) "SOH" is sine = opposite over hypotenuse, "CAH" is cosine = adjacent over hypotenuse and "TOA" is tangent = opposite over adjacent.
The Flintstones was not historically accurate and I don't think your story about chainsaws is either. Both entertaining though.
I'm surprised there isn't an online calculator, to tell you which blocks to assemble, to produce a specific thickness.
since it's not a variable thing couldn't you just mark 6" on the gib, sweep it with an indicator on a surface plate, then have your thou taper per foot?
Keith, since your pivot and the other end are
10.00 inches apart, why not just measure the
fat end of the wedge, and then, measure 10.00
inches away, towards the thin edge?
steve
Why not use the short gib as a template and lay the new one on top (opposite small end over large end) on the magnetic vise? That would provide the angle as the old one was ground? I understand the need to know how to calculate it, however in this case you have a template to grind from....
I got the impression that the old gib was worn in the middle. The magnetic forces would have pulled the new one out of true and produced a faulty grind.
The original gib angle wasn't quite right which, along with the fact that it was too thin is the reason for making the new gib. It can be used to get the angles close but once that is done you need to fine tune the angle until it's right on dimension.
I have a question regarding the math there.
.2078 over 10" works out to .24936 per foot. I suspect that the actual measurement was .25000 per foot.
Do you ever check your measurements to see if they're very nearly a logical number?
Keith why do you need to scrape it in, seems ok as is its flat and dimensionally correct?
Scraping gives a bit of roughness to the surface of the metal so it will hold some oil. If you used just the ground side it could squeeze all the oil out and leave it dry (prone to rust).
That makes perfect sense. Thanks Keith
If at all possible could we get rid of the red line on the preview screenshot? when i scan my videos, it looks so much liked the viewed completion red line i think i have watched this video before.
RUclips puts a mascara ad in Keith's videos, they know how to target their market...
Keith, I do not like just mag., on part with no support on ends, and sides. You can get an assortment of desperate mag., blocks, to block your work pc., in, so there is no accidents!!! You can get blocks as required, it's much safer, believe me, I ran a surface grinder........🍁
This word correct thing, sucks, remove desperate!!! 🍁
Just check it for oil groove purposes, it's done!...🍁
Hi Keith I really enjoy your videos and look forward to the next installment. I was always taught that you should "wring" the gauge blocks together to get a truly accurate stack.
little jumpy there uncle Keith lol... 4:54
I was jumpy for the few seconds afterwards, while he was waving his hands around near the work, with the wheel running, and looking at the camera. I was sure we were going to see a finger fed between the wheel and the work.
He wasn't expecting the large spark off! If you've never seen a wheel let go, you can't completely understand!
@@MaturePatriot yea i got it. i fully understand. im just joking.....
@@jamessonger3 I mean't no offense my friend. I have jumped like Keith did, myself. Have a great evening.
Great video!
I would have liked to see the math the second time, but understand it would have been repetitive and probably boring for many viewers.
Thanks.
Fascinating as ever. Like the new title music.
same music for years...
The light you have on the grinder is the same one i have on my lathe. Sure is a big help
where did y'all buy it, I was noticing it too?
I was going to ask that also, I'd like to buy about 6 of those light's!
Thank you
I got mine off Amazon. It's a sewing machine light
@@apollorobb Thank you!
Well done, excellent results.
Safety glasses?
My father was an engineer, but he couldn't operate a surface grinder because, due to military service, he'd lost the upper register of his hearing, so he couldn't hear the wheel "sing", when it needed dressing.
I remember using one of them in High school, it was great and the teacher always told us to make sure the wheel is clear of the work all along (Test run) and the guard was up too, but the sod forgot to do it his self one day and shot the peace and parts of the wheel out a window that was close to the machine and the bits just missed my self and a friend by inches.
Till a few years ago when he passed, every time we saw and talked we never forget that day,.
He was one of only 4 teachers from that school that understood my work ethic and loved to teach me.