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

Close only counts in horseshoes and hand grenades.
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
 
Do you have the same device? if so, please post pictures.

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
 
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
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

1.JPG

2.JPG

3.JPG
 
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.

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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