Crashed the lathe when threading!!

[D.sebens]

12 inch, that's a huge table. Good luck picking it up.

I hadnt thought about weight but I do have an engine hoist I could use. I was looking for a dividing head since it seems like it’s the most accurate version of this but this came up.

 

[savarin]

You could cut the gears like this

tumbler reverse

Its been a long time since I got any shed time but managed a bit in the last week. Made the angle plate from 8mm plate and welded it together. Managed to control the welding distortion and kept it square. I was rather pleased with the 8x1mm thread, it came out pretty good, not perfect but...

www.hobby-machinist.com

That aluminium gear is still in use today.

 

[woodchucker]

I hadnt thought about weight but I do have an engine hoist I could use. I was looking for a dividing head since it seems like it’s the most accurate version of this but this came up.

I believe in a rotary table over a dividing head. While the rotary table doesn't tilt, it does a lot more than a dividing head. If just doing straight gears, you are better off with a rotary table. A dividing table can't be used for rotary operations on the mill unless you use reverse mills, that rotate counter clockwise, otherwise the chuck will spin off. Rotary tables don't suffer from this if you want to do standard rotary milling (more common for me) than cutting gears. Get a set of dividing plates for your rotary table and you are good to go.

 

[tq60]

Many have done repairs on these.

Use mill or drill press with GOOD fixturing.

Clamp the gear with broken teeth at the very top.

Drill and tap 2 or 3 holes along the root of the teeth. Use a screw just larger than the root.

Use Allen socket screws as they are harder, seek, and buy the good ones.

Thread in to bottom out, use epoxy or good Thread locker.

After full cure, grind off head, then ensert the next screw.

Use die grinder to shape the screws, yplace in lathe and manually rotate to get gear interface good

Use good metal filled epoxy to reform the gear teeth to fill in the gaps. You can place tape over mating gear, and with gear on the shaft, you can rotate it to form the epoxy as it cures.



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[bulgie]

If you braze it, I suggest a "nickel-silver" rod (which contains no silver) like Allstate #11 or Gasflux 72. Temperature range is slightly higher than normal bronze (Cu-Zn) but it's worth it for the higher strength, around 80k psi tensile, likely stronger than the original teeth. Some people like the flux-coated rod but I use bare rod and paste flux. Lots of pre-heating, plenty of flux. The flux is your indicator that the part is hot enough, when it melts and flows. Good flux dissolves in hot water after you're done. I like Gasflux Type B. Beware the generic stuff from the welding shop, some of those do not dissove in water, or not well.

If your filing skilz are adequate, I believe filed teeth will mesh just fine. The only lathe gear I repaired that way was in the '70s, but they continued to use that lathe in production for at least 10 years after that.

Nickel-silver is a bit difficult to file, not so much from the strength but more the 'slipperiness' — the file tends to skate off unless it's very sharp, so start with a new or at least sharp file. Keep checking the mesh with the mating gear as you sneak up on the final shape.

 

[Makintrax73]

Mr Pete did a 6 part series on making a gear copying attachment for a lathe. If someone didn't want to buy a dividing head such a fixture could probably be used to create a new gear with mostly scrap bin metal and the appropriate cutter. Lot of work but cheap. Could use the 3d printed gear as the pattern.

He did several videos on using it to cut gears too. Can't see why you couldn't use the device in a mill just as well as a lathe.

 

[D.sebens]

Well ill be! Those 3d printed gears can work! I have a line on a replacement gear for it from a fellow that converted his to cnc but I’m going to see how long this goes. That 7tpi is quite the turn. A lot of contact and moving fast. I did thread at 29.5* but it’s a lot of thread to turn.

 

[D.sebens]

Made my part and the lathe is still tickin.

 

[Firstram]

. A dividing table can't be used for rotary operations on the mill unless you use reverse mills, that rotate counter clockwise, otherwise the chuck will spin off.

If you move the table back and position the work behind the cutter, it tightens the chuck!

 

[woodchucker]

If you move the table back and position the work behind the cutter, it tightens the chuck!

I think itsnthe revers. If you move the table toward you and work from behind it. Or tool on the left work on the right. Either way. Not optimal
oops, nope, still spins it off. you have to cut in reverse.