gear cutters

I want to cut some gears for my lathe , the back gear set has some missing teeth . 14dp gear cutters are hard to find ! Is this one meant
to cut bevel gears , or is it a reference to the cutter geometry ?
https://www.ebay.com/itm/400847658009?
I guess I always have the option of grinding a single point tool to do the job if I have to . If I go that route I'll probably try building up the broken teeth with some nickel TIG alloy (Invar42). Those gears have been soaking in oil for 70 years now , which may make that problematic . I also have some phosphor bronze filler if that might be a better match .
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"Snag" wrote in message
I want to cut some gears for my lathe , the back gear set has some missing teeth . 14dp gear cutters are hard to find ! Is this one meant to cut bevel gears , or is it a reference to the cutter geometry ?
https://www.ebay.com/itm/400847658009?
I guess I always have the option of grinding a single point tool to do the job if I have to . If I go that route I'll probably try building up the broken teeth with some nickel TIG alloy (Invar42). Those gears have been soaking in oil for 70 years now , which may make that problematic . I also have some phosphor bronze filler if that might be a better match .
---------------------- https://pdfcookie.com/download/workshop-practice-series-volume-17-gears-and-gear-cutting-ivan-lawpdf-j9lgooxqqm2o
Law's book describes a simplified method for grinding a cutter with circular instead of involute curves. For another use I ground a concave circular cutting edge on a lathe bit with a conical stone in a die grinder.
I made two gear cutters using a jig that aligns the lathe bit radial and centered on the tooth gap, and repeatedly grinding down the visible contact spots. It worked, but not particularly well because bluing wouldn't stick to the smooth hard surface. I didn't think to try candle smoke. Both were oddballs, one a 30 degree ANSI spline hydraulic pump shaft and the other the cast iron steering sector on a Roper tractor.
I used the closest-fitting commercial gear cutter I have to rough out the gaps in the blank, because cutting with a single flycutter bit is very slow and wears the tool. You could rough out the gaps with the partly formed bit and finish them after grinding it correctly.
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On 1/13/2022 6:06 AM, Jim Wilkins wrote:


I've got the book ... and I have ground form tools to recut splines which are much smaller than these 14dp gear teeth . I even built a holder to go in my boring head for just this use . Just takes time , a strong light , and a magnifying glass . If you want to smoke something fire up the OA torch ... and I've seen photos of your sector gear and remember you had a bit of a glitch starting out . If I do it this way I'll for sure only cut what I have to , while the noise is annoying the back gears do work - and it's not like I do this every day .
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On 1/13/2022 6:06 AM, Snag wrote:




I would think for a for a single job a single point might be better than buying gear cutters. You can grind it to an exact profile rather than the compromise range of a typical wheel cuter, of course it doesn't really need to be perfect. Almost no gears are.
I found gear cutter sets on one of the China direct sites like Bang Good were pretty cheap, but I never bought any. I have pretty much quit buying from those sites. Most any import item I need is usually on Ebay where my financial info is better shielded for a few dollars more. I have some gear cutters I bought as a lot (new very old stock), but it turned out they are almost all the same cutter. Someday I'll get around to listing them on Fleabay.
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On 1/13/2022 9:42 AM, Bob La Londe wrote:








Looking at the lathe today , I'm onlty missing 2 teeth , Those don't rise to the effort of grinding a cutter . I'll pull the gears out and probably use some brass or bronze to build up the missing teeth . Cut to profile with files and dremel burrs . I was thinking it was more , forgot that I have replaced the bull gear - old one was missing like 2 and a half teeth . Won't be tomorrow though . Tomorrow I gotta bake bread and maybe go to town for some more country style ribs . The ones I picked up today - a buck fifteen a pound! - were awesome !
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On 1/13/2022 6:58 PM, Snag wrote:


Glad you don't have such an involved project. I did run across something this morning that might suit you though. I haven't finished watching it, but I instantly thought of you when it popped up on my feed while I was having my morning coffee.
Cut any gear with just a slitting saw
https://youtu.be/eC-OctJoWv4

https://youtu.be/eC-OctJoWv4

Some folks watch the news or read the paper with their morning coffee. I watch machining videos on the big screen.
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On 1/14/2022 8:12 AM, Bob La Londe wrote:



Part way into the video as he marks out his work I had to smile. I am reminded that I have first handle knowledge of this. If you spin up a Sharpie marker it has a very finite RPM limit. At some speed well below 24000 RPM it will explode.
I was thinking this would be tedious and annoying to make a gear this way, but I do have a 4th axis rotab for the Tormach CNC mill. Then I am reminded if I had the geometry of the gear all figured out anyway I'd probably CNC cut it out of flat bar with some clearance reliefs in the bottom of cut. Either way, let the machine do the work while I go program something else.
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