Missing Gear Tooth

[milomilo]

I have a Husky PC 36 lathe with a missing gear tooth in the quick change gear box. The lathe is a Taiwan product. It is a compound gear. I have got it out and the measurements are:

16 tooth and 32 tooth, 31.25 mm OD on the 16 tooth and 59.50 on the l32 tooth gear. I expect these measurement may be a little undersized due to gear wear. Bore size is 16 mm. Width is 18.95 mm.

It has a copper bushing in the bore. It appears that the small and large gears are pressed together as you can see evidence of two pins in the pics. The missing tooth is on the small gear.

I have searched the net and find no source for parts for my brand of lathe. I expect the gear is kind of a standard gear used in many of the Taiwan lathes.

Hoping someone here may steer me to a source for the gear, or they may have one this size laying around in their shop.

 

[Uglydog]

Welcome to HM!!

We are going to need to identify the DP (diametrical pitch).
If this is a slow speed gear, and depending on the load, you might be able to repair the existing gear.
A welder and a file might work.
For more precision, if you have access to a mill or shaper and a dividing head you can remake the entire gear?
There are a number of HM who might be willing to make it for you.
Or, if you are interested, many of us would rather help you figure out how to make it yourself.

Daryl
MN

 

[omni_dilletante]

If you are shopping for gears these are M1.75 gears. Or Module 1.75.

The module is OD/(Teeth+2).

Module is the metric version of DP.

 

[omni_dilletante]

Bummer for you.

I just did some Googling for Metric Spur gears and it seems that stock gears are Module 1.5 or 2.0. I am not seeing any Module 1.75 gears.

BTW, these are most likely a 20 degree pressure angle. Some of the DP gears are 14.5 degrees, but everything seems to have gone to 20 degrees.

If you convert Module 1.75 to DP you get 14.5. A DP 14 gear will not work. A 16 tooth DP 14 gear would be 32.7mm in diameter. A 32 tooth gear would be 61.7mm. Your measurements would need to be pretty far off for these to be DP14. They are pretty much spot on for M1.75.

You can get a set of Russian gear cutters for about $100 on ebay but that assumes you have a mill, dividing head and 22mm arbor.

 

[Uglydog]

If you are only missing a few teeth. You may be able to repair the existing gear.
Consider making a single tooth involute (think fly cutter).
This is potentially an easy job.

Daryl
MN

 

[savarin]

I cut my spur gear using this guys method. It went easier than I thought it would and the gear is still in constant use.
http://users.picknowl.com.au/~gloaming_agnet/cq9325rev7.html

 

[milomilo]

Welcome to HM!!

We are going to need to identify the DP (diametrical pitch).
If this is a slow speed gear, and depending on the load, you might be able to repair the existing gear.
A welder and a file might work.
For more precision, if you have access to a mill or shaper and a dividing head you can remake the entire gear?
There are a number of HM who might be willing to make it for you.
Or, if you are interested, many of us would rather help you figure out how to make it yourself.

Daryl
MN

I would make it myself if I had a mill, but I don't have a mill or shaper. If I can not find a good used one I may ask if someone here could make me one.

 

[milomilo]

If you are shopping for gears these are M1.75 gears. Or Module 1.75.

The module is OD/(Teeth+2).

Module is the metric version of DP.

Thanks for the info.

If you are only missing a few teeth. You may be able to repair the existing gear.
Consider making a single tooth involute (think fly cutter).
This is potentially an easy job.

Daryl
MN

Just one tooth. I have thought about brazing it but filing would be near impossible because it is up against the larger gear.

 

[Bob Korves]

I have no personal experience with doing all of this, but I think I would take the two gears apart, build up the broken tooth with brazing rod, make a fly cutter type tool like Uglydog mentioned and cut it on a mill with an indexing head. It sounds like you do not have all those tools and skills, but some of the people here have all of them...

Properly done, the gear would be as strong and as useful as it ever was.

 

[bollie7]

As Bob Korves has said, but if you had to, you could file the shape. 40 years ago when I was doing my apprenticeship it was part of the training.
Depending on the size of the gear and tooth, before brazing, you can drill and tap a hole into the root of the root of the broken tooth and then make a steel pin/dowel (whatever you want to call it) and screw into place. (possibly even fit two or more depending on how wide the gear is) Then build the remainder up with braze. File to shape. Time consuming and possibly tedious but with care it can be a quite satisfactory repair.
peter