Gallery, Projects and General > How to's
Cutting Spur Gears -- A neat technique
sparky961:
--- Quote from: xo18thfa on February 22, 2017, 01:24:34 AM ---Quenched tool steel is too brittle at this point and needs tempering.
--- End quote ---
In practice I've found that no tempering is needed when working with brass or other soft metals like aluminum.
In fact, for a one-off tool that's going to see little use you can often get away without tempering the tool for most materials found in the home shop.
xo18thfa:
--- Quote from: bertie_bassett on February 22, 2017, 01:23:41 PM ---nice work
that method is one im planning on using again in the near future to make change gears for my lathe.
last time i tried it didnt quite work, think my cutter wasnt very accurate. and had issues with working out the depth of cut
couple of questions:
a multi tooth cutter would have been easier on your lathe surely? its just a series of v's at the correct spacing. cuting just one tooth as you have must have been quite clunky as it went round and id have thought harder on your lathe?
also from memory you only need about 5 teeth, anymore dosnt help as they dont do any cutting ( unless your cutting a gear with hundreds of teeth.
--- End quote ---
I tried the multi tooth cutter using helicron's method. My little lathe started to chatter a lot and the attempt failed. The single point tool bumped too, but less. I'll re-visit the tool making method again. Yes, 5 or 6 teeth are enough. I did not know what to expect.
According to Mr Law (in his book), depth of cut = 2.157/DP (DP is diametral pitch)
Thanks, Bob
xo18thfa:
--- Quote from: sparky961 on February 22, 2017, 07:33:20 PM ---
--- Quote from: xo18thfa on February 22, 2017, 01:24:34 AM ---Quenched tool steel is too brittle at this point and needs tempering.
--- End quote ---
In practice I've found that no tempering is needed when working with brass or other soft metals like aluminum.
In fact, for a one-off tool that's going to see little use you can often get away without tempering the tool for most materials found in the home shop.
--- End quote ---
Good to know. That saves a step. Wife gets upset when I use her cooking oil anyway
Lew_Merrick_PE:
--- Quote from: sparky961 on February 22, 2017, 07:33:20 PM ---
--- Quote from: xo18thfa on February 22, 2017, 01:24:34 AM ---Quenched tool steel is too brittle at this point and needs tempering.
--- End quote ---
In practice I've found that no tempering is needed when working with brass or other soft metals like aluminum.
In fact, for a one-off tool that's going to see little use you can often get away without tempering the tool for most materials found in the home shop.
--- End quote ---
There are two steps to heat treating steel. 1) Hardening and 2) tempering. The first (hardening) takes the surface of the steel to a Body-Centered-Cubic crystalline form (which is why "hard steel" grows in size). And tempering "relieves the stresses" generated by such a transformation which makes it more resistant to breakage.
sparky961:
--- Quote from: Lew_Merrick_PE on February 23, 2017, 11:57:05 AM ---There are two steps to heat treating steel. 1) Hardening and 2) tempering. The first (hardening) takes the surface of the steel to a Body-Centered-Cubic crystalline form (which is why "hard steel" grows in size). And tempering "relieves the stresses" generated by such a transformation which makes it more resistant to breakage.
--- End quote ---
No arguments here. What you've said is correct. Though I doubt most home shop machinists care what form of crystal the steel is, as long as it does the job.
What I was pointing out was merely a shortcut that you can often get away with - kinda like sex without birth control.
I didn't think it necessary to add the obvious: "Don't come crying to me if your tool shatters" (or if the baby is crying).
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