How do I make it shorter?

[Mosey]

I have some small 15 tooth brass gears, .342 diameter by .270" long, that I need to be .242" long. I have them in a 6K collet that holds them pretty tightly around the teeth. I need to take that .028" off of them. I don't have a collet stop on this SB 10K, and don't think there ever were any. Do I somehow make a collet stop? or do I just go slowly and try not to put any force against the gears that would push them into the collet?
Or, howbout putting them into a chuck with a spider to keep them from pushing in?
Or, in a chuck on the mill table so they can't move away from the cutter?
??? ???

 

[MachineTom]

I'd suggest just what you said, put as much of the gear in the collet and face away. The greater contact area of the collet helps with the grip. Maybe a sharp point rather than a radius on the bit, a straight AL cutter would inpart less axial force than a C bit. Just saw the material is brass, it should be easy then.

 

[kustomkb]

If you are worried about it being pushed in or getting bumped out of parallel you can make a split collet/bushing with a flange on the outside and a shoulder on the inside;

 

[ruzzie]

Hi
Their are some many way to do it here are a couple of quickies
Push them on to a slightly tapered shaft
Use some low strength loctite to hold them on a shaft

Cheers
Paul

 

[stevehuckss396]

I made holders when I needed to modify my gears. I make them a snug fit and hold the holder in a collet. Almost no runout.

 

[Mosey]

I admit that I knew the answers would be good, but underestimated how good the answers would be from you guys. I'm right on it now with some holders. Thanks!

 

[Tin Falcon]

A collet stop would certainly be another option. comercial ones are available for the common types like 5-C . a shop made one should be quite doable
tin

 

[Mosey]

Tin,
Stops seem to be a problem, as I am not able to find any for my 6K collets, and there are no internal threads, so I can't see how to make one. Ideas??
Mosey

 

[kuhncw]

I don't want to divert this thread, but have one request for Paul. I noticed the engine in your avatar. Would you mind posting a photo or two of the little engine, perhaps in a separate thread?

Thanks.

Chuck

 

[Noitoen]

Don't know if I'm allowed to post these links but :hDe:

From here http://www.practicalmachinist.com/vb/south-bend-lathes/what-have-you-made-your-south-bend-147978/index8.html

 

[kustomkb]

Here is the Cadillac of internal, spindle bore, expanding collet stop.

Achim is a member here.

Here is his translated page.

 

[dwentz]

I have a small faceplate that I super glue this stuff to and it has worked well for me in the past. A little heat from the propane torch and a little asitone and all is nice and clean. I have used double sided carpet tape in the past. The real thin stuff and it worked well also.

More than one way to skin a cat.

Dale

 

[Florian]

Well

The easiest (but not the fastest) method is to use the tailstock!
Just put a rod inot the tailstock, fix it to the bed so the rod is 2 cm away from the gear. Then you put the first gear into the collet, adjust with the tailstock to a certian value on the scale.
After adjusting the tool to the right position, you fix it and and then you can start working.


Or, if you have a quick-change toolpost, just put a square piece of material into the toolholder and use it as a bedstop (you can even put a screw into it for fine adjustment) .

First you remove any toolholders from the toolpost.
Then you put the gear into the collet.
Next you put the toolholder with the square material on the toolpost
Now you push the gear against the bedstop and tighten the colled.
Then change the tollholder and machine the gear.

Cheers
Florian

 

[Tin Falcon]

Tin,
Stops seem to be a problem, as I am not able to find any for my 6K collets, and there are no internal threads, so I can't see how to make one. Ideas??
Mosey

Yep !!! tool catalogs are great inspiration for ideas. Here is a instruction sheet for a Hardinge 5C universal collet stop complete with sectional diagram and parts list.
http://www.shophardinge.com/assets/PDFfiles/B039B.pdf


You could make one similar to An MSC #09682501

this has an expandable Delrin sleeve the main body is aluminum . the stop rod is also aluminum so easily machined easily replaced easy to have a half dozen for various uses.
these examples are 5C but i would think one could change the dimension to other collet families.


Patent drawings can also give ideas
http://www.freepatentsonline.com/2771297.pdf
this drawing uses eccentrics to lock the stop in place.

And last but not least the old Popular Mechanics Magazines
PM Jan 1956 pg 234
I think between the four examples with photo or drawing you should be able to make one to your liking.
I will send the bill for the research ;D
Tin

 

[MachineTom]

What you need to do is make a collet stop in the drawtube. Drill a hole a short distance from the end of the threads. Tap that hole for a set screw, 10-32 size, make a threaded disk slip fit into the tube, with a drilled to line up with the setscrew, and exact depth to allow the setscrew to bottom in said hole, and be flush with the outer surface of the drawtube. The threads in the disk 20 tpi so one turn is .050", a couple different lenght all thread screws with slotted ends, jam nut, your done.

 

[Tin Falcon]

collet tube stops are certainly another option.
Here is another quick fix option from an old pm mag.
Surface collet stop
Tin

 

[Swede]

I know you have a less common collet, but for those working with 5C, one of the cheap "emergency" collets can be bored out with an internal shoulder for just this sort of task.

All these answers are sound, and they should work. Any time I'm worried about the rigidity of a setup, I take more, lighter cuts with a razor sharp tool. Less cutting force = less chance of deflection.

 

[Tin Falcon]

another option not sure if it was mentioned is a pot chuck

the photo is a 3c from tools4cheap.
these are also called pot collets.
Tin

 

[steamer]

+1 for the 5C "emergency" collets or the pot chucks....They come in real handy when you have an oddball or a thin part like a washer of some sort.

Dave

 

[Tin Falcon]

If you have a lathe that has soft jaws they can be machined to fit stuff as well.

tin