Arbor for mill advice

[pjf134]

Arbor for mill advice
 I have a Sherline 2000 CNC mill with a rotary table and I want to make some gears with it. I need to make a arbor for it to hold the blank. I was thinking of using 2 threaded nuts to hold the blank on the arbor and was wondering if anyone tried this before. I was thinking of making it a small dia. rod and enlarging the center of the gear after it was cut otherwise I will have to make a few different size arbors. I think I have a tail stock for it and if I don't will have to make one. The mill was free with a box of tooling for it and the Sherline CNC lathe was free too with a box of tooling also, some of the extras are still in boxes so not sure what is in them since I looked last. Every gear I made was done on a automatic gear cutter when I worked in a machine shop so this way is new to me. I could use a 3 or 4 jaw on the rotary an I was going to use a fly cutter with a gear profile cutter to cut the gear teeth. Any input would be appreciated. Pic shows what I have so far.
Paul

[cfellows]

I did something much the same for my dividing head.  I made up a 3/4" arbor with a 1/4" diameter stub in the lathe, then threaded the stub to within about 3/16" of the shoulder.  Mine has a #2 morse taper with a draw bolt to fit my dividing head, but a straight shank works as well.  As you've probably discovered, the gear blank needs to be well away from your chuck so you don't run into it with the gear cutter.

Here's a picture.

[cfellows]

Here's another, double ended arbor I made.  It's a 3" (could be longer if needed) length of 5/8" cold rolled steel.  The small end has a 3/16" tip with a 6-32 socket head cap screw.  The clearance shoulder behind it is 1/2" diameter & 3/8" long.   The other end has a 3/8" tip on it with a 1/4" bolt to secure the work.  The half inch diameter step behind it is to allow mounting a larger blank with a 1/2" center hole.

Most of my gears are 24 pitch and are 1/2" up to maybe 1.5" diameter.

Chuck

[pjf134]

 Chuck,
  That looks like a good idea to use. My gears are most likely go up to 6" dia. and did you use a tail stock with that setup. I do have to make 2 gears that are about 7" dia. with the teeth facing inward, but I think I will just mill it in flat position for those 2. The chuck in the pic is 2 1/2" dia. so if I make some bigger gears I could get the blank closer to the chuck without hitting it with the cutter.
 Paul

[cfellows]

Chuck,
  That looks like a good idea to use. My gears are most likely go up to 6" dia. and did you use a tail stock with that setup. I do have to make 2 gears that are about 7" dia. with the teeth facing inward, but I think I will just mill it in flat position for those 2. The chuck in the pic is 2 1/2" dia. so if I make some bigger gears I could get the blank closer to the chuck without hitting it with the cutter.
 Paul

I don't use a tailstock.  For smaller gears, the overhang on the first arbor doesn't seem to be a problem.  I've used cast iron gear blanks and usually cut 24 pitch gears in one pass.  For larger pitches, either use multiple passes or, as you say, mount the blank closer to the chuck and you shouldn't have a problem.

Chuck

[pjf134]

 Chuck,
  I think I will go for the first arbor mounted in the chuck on the rotary table and see how that goes and go from there.
 Paul

[pjf134]

 Chuck,
  After posting the last one I went and starting making a arbor from 3/4" dia. CR and went to my tool box for a die to thread the end and I found 2 arbors like the one I was making just 7/8" dia. I made them back in the mid 90's for a machine of mine that I was altering, but it would not be called a arbor, just looks like one. Forgot I made them and now I have 3. I keep finding things I made on a lathe 40 plus years later, I just forget that I have them and did not use them for a long time, but do remember when I made them once I see them and why I made it in the first place most of the time.
 Paul