Metric 127 tooth change gear location

cathead

cathead

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I now have dividing head capability to make a 127 tooth gear for metric threading. My lathe is a Monarch 14C.
My question is where in the gear train does this gear go? Does it replace an existing gear or used as a gear reduction possibly?
 
The problem with the Monarch (I had one, 14CK) same but with lead screw reverse on the carriage, the problem is that there IS no place to mount the translating gears due to the design of the machine. I have a chart that I drew up for metric threading and would be happy to fwd it to you
USPS would be the easiest for me, PM me and we can arrange it.
John
 
It should replace the big idler gear, but used in compound with a 100 tooth or 120 tooth gear. Been a long time since I've looked at a Monarch, I believe most were set up to use a 37/47 compound gear instead of a 127 tooth gear because of room in the gear train.

Ken
 
Yes that would be true, but also there are other change gears necessary, and I think my chart would still work for the 37/47 compound gear The spindle gear drives the larger compound gear, and the smaller one drives the change box. I think my chart will work with any lathe with a 4 pitch lead screw.
 
Thank you John and Ken for the replies. I need to take a good look at the gearing to see what I am up against.
It appears that even with the 127 tooth gear, it may not be a simple thing to accomplish. I will post again once
I have a better idea of the details of the gear train. Also I have an old Springfield Ideal that could possibly be utilized
to do metric so will be looking at that as well.
 
Yes, the Springfield would undoubtedly a easier route; I looked at my 14 CK and just walked away, and converted both of the 19" Regals that I had for metric; I'd have thought that a toolroom lathe would have been much more adaptable to cutting metric and special leads, but not so in this case.
 
I will take a good look at the Springfield today.....................The wheels are turning now... :)
I have the involute gear set for 16dp which is what is used on the Springfield so it might be doable.

Thanks, John.
 
Today I procured some 1/2 inch flat hot roll material to make some gear blanks for the Springfield Ideal metric modification project.
The plan is to replace one existing change gear pair with an altered pair to provide metric carriage travel. I decided to go with the
63/80 which will give me a 1.2698412 to 1 ratio which is close enough to 1.27 to 1 for all practical purposes. With that thought I
made a pair of 1/2 inch thick gear blanks for 80 and 63 teeth in 16dp and 14.5 pressure angle. This is going to require a wide idler
gear to run on both gears and transmit the power to the 8tpi lead screw. Of course this will reverse the travel of the carriage but
with having a reverse already, it should not be a problem. I don't have the correct involute cutter so will have to come up with a
cutter somehow. My involute cutters have a one inch ID and what I find on line is 22 millimeter ID cutters so a little smaller inside.
Maybe I will have to make a 22mm arbor if I can't find a one inch ID cutter.


P1020199.JPG

Machining was pretty easy using a Morse taper arbor stuffed into the Monarch. It was a lot of hot
chips in interrupted cuts as I shaped some squares into rounds. I got no complaints from the carbide
cutter so consider myself lucky in that respect.



The spacing between the two gear blank holes has to be 3.2 inches.
This forces me to go with an idler in the gear train. I can see that I
will have to build up a casing of some sort to hold the idler in position
for this project.


The gear blanks pictured above will replace one of the pairs of change
gears for power transmission. The usual ratios are 1-1, 2-1, 1-2,
1-4, and 4-1 for the gear pairs. Then I will have 1 to 1.27 and 1.27 to 1
for metric options.


edit: I may have to rethink this as apparently it will only give me a limited range
in this configuration. What I really need is to introduce the 1.27 to 1 ratio
and still have function of the change gear sets. It's not clear to me how
this can be done...
 
Last edited:
cathead said:
I now have dividing head capability to make a 127 tooth gear for metric threading. My lathe is a Monarch 14C.
My question is where in the gear train does this gear go? Does it replace an existing gear or used as a gear reduction possibly?
Click to expand...
I'm interested to make a similar 127T gear for my Hendey. I'm looking at a dividing head someone has for sale, an older BS-1 style unit. Is yours also 40:1 reduction, and if so what circle—which hole count—gets you to 1/127 of a spindle rotation? Looking at this calculator

CGTK - Dividing Head Calculator

www.cgtk.co.uk www.cgtk.co.uk
and the three hole plates that come with the dividing head I'm considering, it seems I could not divide a circle into 127 sectors.
 
Yes, it is true that a dividing head without the capability to differential indexing cannot index 127 divisions, unless it would accomodate a 127 hole plate, which nearly any dividing head cannot accomodate, even if one were available. A universal dividing head can do the job by, through a train of gears integrates the spindle rotation back through to the dividing plate, so that as the worm shaft is rotated, the dividing plate also rotates either faster or slower in relation to the worm shaft rotation; the universal dividing heads were not manufactured in the smaller than 10" swing (#2) size dividing heads. Using a #2 universal head, I made a 127 tooth change gear to fit my automatic gear cutter, and so, can cut change gears of virtually any diametral pitch.
 
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