Random lathe stuff, chat, questions, tips, etc.

[VPT]

Started this thread just for a place to throw out quick thoughts, questions, etc.


I made a MT3 dead center for the lathe headstock yesterday out of some chormoly bar I had laying around. Today I was pondering and looking at the torn up reverse gears in my old reverse box that came with the lathe.

Just for fun I set up the unimat headstock mounted off the compound (counted 5 axises set up like this) and threw one of the old gears in the 3 jaw chuck. I was able to line up one of the extra 45 degree cutters with the gear teeth. The compound would line up with the gear taper, cross slide worked out for infeed, and all the other axis adjustments worked out to get just the right angles to cut the teeth. Unfortunatly there are 60 indexing holes on the bull gear and 18 teeth on the gear so it comes up to 3.33333. But I tried out a piece of aluminum stock anyhow and cut a few teeth at every 3 indexing holes. It seemed to work out great! I would have to cut one side of all 18 teeth than reset up the unimat to cut the other side of the 18 teeth. But it does look possible with a better setup for indexing. The unimat cut the aluminum with the 1/2" 45 degree cutter without a problem. I was able to cut each slot in about 4-5 passes. I think with a good index set up I would be able to cut all the teeth (both sides) in about 30-45 minutes.

Any ideas for an indexing setup?







Yeah, I did cut and started to cut a couple slots at 4 indexing holes apart. These slots are only cut on one side, the unimat would have the be angled a bit more to cut the face of the opposing wall of the slot.

[Deanofid]

Hi Andy;

I don't have this particular model of Atlas, but here are a couple of ideas that may head you in the general direction.

You can use your change gears and an index pin. Figure out a place to attach a simple pin setup behind the gear cover. All that needs to be is a simple metal block with a hole drilled through it for a pin. Find a way to attach it, like clamping it on the banjo or bolt it to a convenient hole. Make a pin to fit the hole in the block, and grind a "V" shape on one end to match gear teeth. Work out a gear ratio that will give you a gear in the train that will evenly space 18 spaces. Keep the backlash out of the gear train and it should work well.

Or, find anything with 18 spaces that you can attach to the spindle bore. Another gear, a sprocket, what have you. Turn up an expanding plug to hold it in the bore of the spindle, or make a collar that will do the same thing putting it in place of the spindle gear.

I'll suggest something for your gear cutter. Grind up a single point cutter from HSS that matches the profile of the gear teeth on the old gear. Hold it similar to a fly cutter. In aluminum, these work very well. I've cut lots of gears this way. You won't have to mess with the double setups on your milling head.

Dean

[Rubes]

I had seen this on another site recently. How many teeth are on your bull gear? can you do something like this? kind of along what Dean was sayin'.

[VPT]

Thanks for the great ideas! I thought the index holes matched the teeth on the bull gear but looking at this pic they don't. So the bull gear teeth may have right number of teeth. An 18 tooth change gear is also a good idea!



I was trying to find an appropriate endmill in my pile that would be close to the shape of the teeth I wanted to cut but the 45 degree cutter was the closest. The HSS grind in a small fly cutter is also a great idea! Thanks for that as well!


The only problem with two of the gears in the reverse box are the cog teeth. I still haven't figured out how I am going to cut these.

[Shotgun]

Would it make sense to cut two gears? Then you're guaranteed a match. Plus, if the one is all busted up is the matching one cracked and just waiting to go as soon as you get it back together?

[VPT]

If this goes as simple as I think it should I will most likely make all 3 gears in the reverse box.

[paulsv]

[quote=VPT;4985]Thanks for the great ideas! I thought the index holes matched the teeth on the bull gear but looking at this pic they don't. So the bull gear teeth may have right number of teeth.

Well, I counted the teeth three times, and came up with 69 teeth each time. So it will be useful if you want to divide a circle into a number of parts equal to 69, or any number evenly divisible into....... Well, let's see, that would be 69, 23, 3 or 1.

[kenwc]

With you're tenacity....I'm sure you'll succeed.

Originally Posted by VPT

If this goes as simple as I think it should I will most likely make all 3 gears in the reverse box.

[gkemper]

What I did to scribe the 200 lines on the dial I made was to use a CAD program to draw and print out as large a circle as I could on a piece of paper.

This circle had the marks on the circumference I wanted to divide the circle into.

I then glued it to a piece of cardboard and using a spacer I attacked it to the rear end of the head stock spindle (centered of course).

Then I just attached a wire to a fixed location to use as a pointer. Put the lathe into back gear and pull the belt to rotate to my marks.

It is amazingly accurate. The larger the circle the more resolution you get.

[paulsv]

Wow, Gary- beautiful result, and a very creative way of doing it!