how to hold a spline in chuck

[scott m]

Actually what I will have is a 12" long round bar of brass with teeth cut in it running parallel to the lathe center line. I am going to cut these teeth with a special toolpost cutter. What I would like to do is turn hubs and shave gear blanks from this bar with a cutoff tool but it is too big to go through my spindle hole. I first thought about making a internal gear of the same pitch with a smooth outside and a slice in it, kind of like a split nut used to hold threaded items. Two would work, one in the chuck and one in a steadyrest but I have never made a gear like that yet. Would there be an easy way to hold something like that without damaging the teeth? TIA. Scott.

[HuFlungDung]

Yes. A 5C collet would be the answer. If there is not one made the right size, then you can buy an "emergency collet" and bore it to size yourself.

For a few bucks, you can buy a 5C adapter socket that you can use to hold the collet in a regular lathe chuck.

[ViperTX]

So, I would turn a piece of delrin and bore the delrin to a little less then the diameter of the gear rod (or whatever you want to call it)...I would then slit the delrin...slip it onto the end of the gear rod...for the steady rest use a similar piece of delrin...bored to just snuggly slip over the rod...you'll have to center drill the gear rod....I suspect that you'll need it to center the gear rod accurately.

[DareBee]

I am confused!
These answers dont seem to follow along in logic. Is something missing?

[scott m]

I like both of those ideas, maybe leaning to the delrin suggestion. It will have a center drill hole in the end anyway. The only thing I can see is probably not slitting the ring that goes in steady to keep from bumping on all three of the "fingers". I think a push fit would do it. Has anyone ever cut a internal type ring gear? I have a small hand made shaper and a homemade indexer for it so I might try it anyway. Scott.

[Kmed]

I dont know what module gear you are cutting but beware that if your center hole is off by .002 or more you can jam your gears very easily (pitch diameter is different for different modules). In our machine gear boxes, we recieved plates to print +/- .001 for hole location but the gears were .002 instead of .001 TIR. This actually bound up the gear box and was frustrating as hell to figure out the problem. The plates varied within spec but gears that were out of spec would sometimes bind depending on what direction the pin plate varried. Hence we moved manufacting of precision part in house. THis has negated the pin plate issue, and the gear issue was fixed by changing manufacture. All of the in house gear blanks I have cut have worked but watch for perpendicularity of your center hole as my tail stock was off slightly and the first 3 gears I cut off would be in spec and the next 4 would be off. Took a precision pin and time to align the tail stock, ohh and a albrecht chuck

[scott m]

I am cutting 32 pitch gears, of different od's and tooth counts. The way I am doing it is mount the stock with a chuck and steady, after center drilling/drilling/reaming to bore size, then turning the od and then I mount the cutter in the toolpost and hack out the tooth forms, indexing the spindle. Then, I cut the hub with a square formed cutting tool (so I don't have to change tools to cut right and left) and part off. I can't imagine how the hole could be off but thanks for the warning and I will keep an eye peeled on it. Delrin works mighty good . Scott.