- Joined
- Oct 20, 2014
- Messages
- 159
Well I got antsy and wanted to see if I could just machine the gear using standard tools, instead of the custom cutter stuff. Or I should say, earlier, than the custom cutter stuff. I will still most definitely be doing the custom cutter tooth stuff when my O1 and W1 rods get here.
So...my ingredients included:
-block of nylon I had in the scrap bin..not sure exactly what nylon
-turns out a cutter with a 78 thou radius will get within a couple though of the curvature of the teeth for these DP gears! And lo and behold. I had some weird HSS end mill that was 78 thou, and somehow had also hand ground the shank to be smaller, so it had a longer reach! WTF! First time I tried it it broke though on the deepest cut, the chip clearance wasn't so hot, and I dont have the feeds and speeds dialed in yet for a cutter that size in nylon. Luckily it was double sided so I ground the other end to be skinnier for longer and that worked.
-The nylon had lots of burrs, I dont machine nylon very often so I just took pretty wild a%% guesses about the feedrates. I was able to clean up the gear afterwards but its dumb to have to do that. So if I end up making a bunch of these I'll do some experiments and get the feedrates and rpm perfected, and/or make it out of a different plastic. I didnt have any delrin on hand.
-Looks like the teeth mesh great!
-The threaded holes are for the fixture so I can flip it over and machine the other side. I mic'd the bore diamter and keyway diameters.
-I had to file the keyways inside radiuses flat because I dont have an endmill that cuts square holes yet, cant seem to find one for sale. I guess next time I'll have to just go in deeper so the radius clears the existing geometry but I didnt want to deal with that this time.
-I made a 32 tooth gear, because thats all I need to be able to do 27 TPI with the other gears I have. Not that I really need 27tpi but at least I can try this out with just one CNC'd gear.
-The toolpath took about 13 minutes, totally hands off, 5 tools. But all the feed rates for the small cutters were guesses. I'm not sure how long it would take once I get it all dialed in. I'm guessing at least twice or three times faster possibly.
-Nothing too special about the toolpath. The model was courtesy of emachineshop.coms spur gear generator in its CAD package. Exported as DXF, imported in solidworks (turn OFF constraints and merge points), then extruded, and modified to have all the Atlas Lathe geometry. No spokes on this one because its so small. All the Atlas gear measurements are pretty basic. Looks like I got it right the first time. Camworks for the toolpath. All of its 2.5 axis stuff.
-Man the Atlas really is a pain to change gears on. I guess if I print out the gear change chart and put it near the lathe that might help. But why did they put the bracket nut on the BACK of the bracket so you have to reach around backwards and use a flashlight and struggle to get a wrench in there. Am I missing something??
-So got it in the Atlas and started her up. Hey it works!! Not sure how it would handle a crash but for actual threading might actually do the job.
I have since bought a couple HSS 1/32" and 5/64" end mills off ebay because I have a feeling I will be making alot more gears!
BTW if anyone wants a special change gear (i.e. special number of teeth) for something interesting on the Atlas 10F let me know and I may be able to make you one!
So...my ingredients included:
-block of nylon I had in the scrap bin..not sure exactly what nylon
-turns out a cutter with a 78 thou radius will get within a couple though of the curvature of the teeth for these DP gears! And lo and behold. I had some weird HSS end mill that was 78 thou, and somehow had also hand ground the shank to be smaller, so it had a longer reach! WTF! First time I tried it it broke though on the deepest cut, the chip clearance wasn't so hot, and I dont have the feeds and speeds dialed in yet for a cutter that size in nylon. Luckily it was double sided so I ground the other end to be skinnier for longer and that worked.
-The nylon had lots of burrs, I dont machine nylon very often so I just took pretty wild a%% guesses about the feedrates. I was able to clean up the gear afterwards but its dumb to have to do that. So if I end up making a bunch of these I'll do some experiments and get the feedrates and rpm perfected, and/or make it out of a different plastic. I didnt have any delrin on hand.
-Looks like the teeth mesh great!
-The threaded holes are for the fixture so I can flip it over and machine the other side. I mic'd the bore diamter and keyway diameters.
-I had to file the keyways inside radiuses flat because I dont have an endmill that cuts square holes yet, cant seem to find one for sale. I guess next time I'll have to just go in deeper so the radius clears the existing geometry but I didnt want to deal with that this time.
-I made a 32 tooth gear, because thats all I need to be able to do 27 TPI with the other gears I have. Not that I really need 27tpi but at least I can try this out with just one CNC'd gear.
-The toolpath took about 13 minutes, totally hands off, 5 tools. But all the feed rates for the small cutters were guesses. I'm not sure how long it would take once I get it all dialed in. I'm guessing at least twice or three times faster possibly.
-Nothing too special about the toolpath. The model was courtesy of emachineshop.coms spur gear generator in its CAD package. Exported as DXF, imported in solidworks (turn OFF constraints and merge points), then extruded, and modified to have all the Atlas Lathe geometry. No spokes on this one because its so small. All the Atlas gear measurements are pretty basic. Looks like I got it right the first time. Camworks for the toolpath. All of its 2.5 axis stuff.
-Man the Atlas really is a pain to change gears on. I guess if I print out the gear change chart and put it near the lathe that might help. But why did they put the bracket nut on the BACK of the bracket so you have to reach around backwards and use a flashlight and struggle to get a wrench in there. Am I missing something??
-So got it in the Atlas and started her up. Hey it works!! Not sure how it would handle a crash but for actual threading might actually do the job.
I have since bought a couple HSS 1/32" and 5/64" end mills off ebay because I have a feeling I will be making alot more gears!
BTW if anyone wants a special change gear (i.e. special number of teeth) for something interesting on the Atlas 10F let me know and I may be able to make you one!
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