Garrett Wide Range Attachment (AKA, Garrett Millerette) for Lathes.

benmychree said:
Close only counts in horseshoes and hand grenades.
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Depends on what you are doing. The accumulated error (53 times) is just over 1/2 a degree - but it accumulates into 1 position! I am looking for an exact method (without using a 53 tooth gear!). On a side note - a 53 tooth front chainwheel on a bicycle is common, so it would be a good starting point to make a 53 tooth gear
 
Eddyde said:
Do you have the same device? if so, please post pictures.
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Hi Eddy,
I saw one a while ago (end of Nov. 2017) at my local used tool place.
I only recognized it because of this thread, but I took a couple photos:

20171125_154959.jpg 20171125_154952.jpg

I kinda lost track of this thread and never got around to getting them off my phone, until the thread was updated.
Sorry, they had no manual.

-brino
 
JonHolmes said:
Depends on what you are doing. The accumulated error (53 times) is just over 1/2 a degree - but it accumulates into 1 position! I am looking for an exact method (without using a 53 tooth gear!). On a side note - a 53 tooth front chainwheel on a bicycle is common, so it would be a good starting point to make a 53 tooth gear
Click to expand...
On my B&S mill, this would be done by differential indexing; on the Cincinnati dividing head, a plate with a 53 hole circle is provided so that it could be divided by plain indexing. Likely that is the answer to the current discussion; a 53 tooth change gear would likely be needed.
 
I note that the Millerette dividing head seems to be a 90:1 ratio, somewhat unusual , as the "normal" ratio is 40 :1; there was one with a 5:1 ratio for long spiral cutting, and some rotary tables are 90:1. It would seem that this design was an effort to eliminate errors in indexing.
 
Eddy,
I have a few photos. I have the original dividing head - with an additional user made base (green) - the tailstock attachment, a holding device and all 24 gears (15T to 31T, and 35,37,41, 43, 47, 49 and 60 - 24DP) and a few user made taper adapters (the taper is like an "extended" 2mt - extend the large end, and remove off the small end). Also a small 3 jaw chuck has been adapted to fit - not in photos

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benmychree said:
I note that the Millerette dividing head seems to be a 90:1 ratio, somewhat unusual , as the "normal" ratio is 40 :1; there was one with a 5:1 ratio for long spiral cutting, and some rotary tables are 90:1. It would seem that this design was an effort to eliminate errors in indexing.
Click to expand...

Yes, 90:1. As well, the handle is intended to be turned in whole turns - no fractional turns are really possible. Again probably to reduce the risk of errors.
 
What a magnificent piece!
I however did get lost in the math about halfway through the discussion.
Back to the books for me. (sez the guy who can mess up on a RoTab...)
 
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