MFC Milling Machine - Seeking Auto Feed gear repair advice.

[spongerich]

I finally got my MFC running this weekend and I discovered that the bevel gears in the auto feed are badly worn. There's only one set on eBay right now and they're $180 - ouch.

Since I have a lathe and a shaper, I was thinking that it would be reasonably simple to have someone fill them with brazing so I could re-machine the teeth. In my mind, the biggest challenge is holding and indexing the parts. My first thought is to hold the cutter in a toolholder so it's perpindicular to the table. Then if I mount my spindex 45 degrees from the axis of the ram, I should be able to cut the bevel teeth.

3A and 4A are the ones that are worn out.



Any other ideas?

 

[34_40]

I'm not 200% certain but I think the gears are made of a material called Zamak. And I don't believe they can be welded.

There are a couple more knowledgeable guys that will know for sure I think, check back later and maybe they'll have a chance to reply.

Sorry.

 

[spongerich]

I'm not 200% certain but I think the gears are made of a material called Zamak. And I don't believe they can be welded.

There are a couple more knowledgeable guys that will know for sure I think, check back later and maybe they'll have a chance to reply.

Sorry.

The table feed gears are steel, so brazing them no problem, however, some research has revealed that cutting bevel gears in the home shop is quite a bit more complicated than it appears at first glance because of the geometry of the gears.

The diameter of one end of the gear is larger than the other, yet the tooth count is (obviously) the same, so the width of the teeth varies.

Plan B looks like it's going to be to find some off the shelf bevel gears and modify them to fit. In the meantime, manual feed isn't terrible. I might adapt a larger crank or a wheel to get an easier smoother feed. I have plenty of handwheels from Atlas aprons/tailstocks that I can fit.

 

[benmychree]

Don't waste your time brazing; if you need to replace them, make new ones from scratch; you are right about cutting bevel gears; it tales a special (bevel gear) cutter, and at least three cuts to generate an acceptable tooth shape; look in Brown & Sharpe's " Practical Treatise on Gearing" for a description of the process.