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A brass dividing attachment I made for a rotary table.

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george wilson

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This was made for a rotary table I have,which,as most do,had a 90 to 1 gear ratio. So,somewhere I found the needed numbers of holes in the dividing plate to go with the rotary table. Most dividing attachments are 40-1 ratio(unless my old head is forgetful this A.M.!~)

I drilled all the holes by first walking a very sharp legged Starrett divider around the very thin lines I scored while the round brass plate was still in the lathe. Then,after several experimental trips around the scribed line,I center punched where each hole was to be,then drilled each hole out with a PUMP DRILL,as used by clock makers in the 18th. C..

When I got the plate all pre drilled,and back to my home shop,I went over all the holes with a very small lathe type center drill,which deepened the holes a bit,and added the bevels around each hole.

Those small holes seen in picture #2 are 1/32" high with serifs! I LOVE old,high quality letter and number stamps. I've searched for each set I have till I have all the sizes. I SWEAR that one set have is 18th. C.. It is made of crudely rolled steel with one side left round. But the letters are PROPER ROMAN letters,with thick and thin letters. The A ' for example,has a thick leg,and the other is thin,etc.. The TOPS of these stamps had EVER been struck,as they had been left as cut off with a hot chisel at the forge. You were expected to grind them flat,which I did reluctantly. Way back then,you had to make your own chisel handles,and sharpen your new saw,which had teeth pre punched,but not sharpened. This makes me think these particular stamps are 18th. C.. They were so FRUGAL about every thing back then,to keep costs down.

The knurled parts were knurled with a knurl I had made. This knurl was made by putting a tap in the lathe chuck,mounting the blank knurl wheel in a holder that allowed it to freely rotate. The tap just let the knurl blank go around and around till the impressions were cut into the wheel,making it into a knurl. The knurl was made from either 01 or W1 steel drill rod. I always stamp each knurl with which steel I used,should I ever want to change the temper long after I'd forgotten what steel I had used.

I always handle this attachment with surgical type nitrile gloves,to protect the beautiful golden color that the alloy 260 brass has turned. I don't care much for the fresh polished color of 260 as it has a little green color in it. I was able back then to buy brass from the museum warehouse,and they stocked 260 sheet up to 1/4" thick.

I can't do that any more. When the Warehouse foreman was caught pocketing the money from employee purchases,the knee jerk reaction was to stop employee sales. Not fair. WE weren't pocketing the money!

The first picture shows the true color the best. A few pictures are to show the old fashioned"Microscope" knurls which you could also learn to make. But it is CAREFUL work,lest you snap off the tap!

dividing plate.jpg

dividing plate 2.jpg

dividing head 2.jpg

dividing plate knob.jpg
 

george wilson

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Thank you,f350ca. Read my post again if you want more info, as I was adding information while you were reading the first post.
 

chips&more

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Very nice work George! Some old clocks also use that rounded knurl. I have a dozen or so knurls that I have made. Every time I go to make a knurl to repair an old clock, none of my knurls match! So I make another one. Some things were just not standard back then! Most of my toys in my shop have handles. But I set-up a dividing head with a stepper and Arduino. Don’t need to worry anymore about those divisions that can’t be done on a diving head. I just push a button and go. No more cranking, trying to remember how many turns you made, don’t count the hole you are in and all of that dividing head stuff/oops...Dave
 
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woodchucker

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This was made for a rotary table I have,which,as most do,had a 90 to 1 gear ratio. So,somewhere I found the needed numbers of holes in the dividing plate to go with the rotary table. Most dividing attachments are 40-1 ratio(unless my old head is forgetful this A.M.!~)
...
The first picture shows the true color the best. A few pictures are to show the old fashioned"Microscope" knurls which you could also learn to make. But it is CAREFUL work,lest you snap off the tap!
beautiful work George, now gotta look up a pump drill
 
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f350ca

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Beautiful work as usual George. Something to aspire to, Im afraid none of my tooling its finished to the degree that requires handling with gloves. I love the look of straight knurls as you've done there. Think I need to try making a knurl to do them. I've seen worm wheels cut as you describe making the knurl. Would you not get an angled profile following the pitch of the tap, or if so does it not show up in the final product. Can't quite tell from the photo.
Thanks and thanks for posting.

Greg
 

Silverbullet

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Almost to nice to use, really nice work. Takes a machinist to build this, not button pushers on CNC machines. Being old school gets it done . Most couldn't even walk the circle with dividers or hermaphrodite dividers for set up. My old apron pockets had the essential tools , 0-1 Mic, 6" scales hard and bendable, scriber, auto center punch, hermaphrodite and point dividers. 10" adjustable wrench. 8ounce ball pein hammer. Anywhere in the shop I was needed to help keep the shop running. You'd be surprised how many times I was called by other machinist to help layouts.
Really beautiful job , I enjoy brass jobs myself , some tricks to working it too. A lot just drilling holes.
 

woodchucker

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I have few Yankee push drill/screw drivers, but what I found was different for pump drills. I found something akin to a fire starter, where you use a string and a stick or bow to turn it back and forth. George also had made one in a previous post of his, although I only saw a portion of it. But I have the idea for both..
 
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Silverbullet

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Yankee model 50 I think is the one I consider a pump drill , the bit only turns one direction so it doesn't wear the sharp edge on the stroke they cut both ways up or down stroke. The push drills reverse the bit during the up stroke.
 

woodchucker

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Yankee model 50 I think is the one I consider a pump drill , the bit only turns one direction so it doesn't wear the sharp edge on the stroke they cut both ways up or down stroke. The push drills reverse the bit during the up stroke.
good info, I'll check which ones I have.
 

george wilson

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The pump drills I referred to are 18th. C. type,used for hundreds of years. They have a tall shaft with a flywheel on it. A cross handle with a stout string is attached to the vertical shaft. Winding the string around the shaft and putting the drill point where you want it,and pulling down the cross handle starts the flywheel rotating. The bits are flat bits with their cutting edges ground on similar to modern drill bits,but no spiral. These drills are not meant for deep holes as the will stall out the pump drill. Still used by many watch makers and silversmiths.

Look way down the list of my projecvts and you will see pump drills I made. 6 of them.
 

Tim9

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Just beautiful workmanship.
 
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