Indexing on lathe

So here is how i get my lathe to stay put while we cut flutes or flat spots, as used on our Bullpup Condor. All were made on the lathe as well. First is the index wheel.


The brake for holding in any position.


And getting ready to cut a flute, also used to cut the loading port, sear to hammer access, ect.

Hope everyone has had a great holiday season…


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Oh it might take a bit to knock it open, but on the BULLPUP model of ours it was no problem, we actually have extra noise from the breech slide whacking the top of the tank. Of course this was what we planned on for valve travel limit so we will do the resilient plastic insert. I had already done this for hammer slap, and what a difference. I’ll have to test my springs for strength, but I think they are fairly stout, just what the parts store had in stock. Beggars can’t be choosers, I hope we can find some other parts this weekend when we go to the coast. Maybe pick up some more tube for a couple of more shrouds, and brass for a valve or two. All that stuff is scarce around here, a two hour drive to hope to get anything. And the coast is 500 km. So gotta buy something so i don’t waste a trip. Oh well, if I am lacking in material I might think more before I waste it.

Hey Camotes, have you done a valve stem that large before? Isnt it gonna take a BIG spring and hammer to knock that thing open?

😯 Ingenious!!!!!!

Awesome and creative, great work and thanks for sharing your techniques and ideas!!!


Nice works love the picts. To many ideas my head is spinning.

Thanks 😀

So here are a couple of pics first is the whole milling head. sometime I want to put a heavy flywheel on the mandrel so it might be smoother instead of relying on horsepower to cut via the tooth belt, I will have the flywheels energy.


And here is a close-up of the ports being cut on my son’s .30 cal build. I am sure learning patience letting him do it all. But I guess I was there once upon a time?


Then here is a pic of the ports finished to size. This time the valve stem has a barrell size hole through it so no hinderance for air flow. Then to make sure we have enough circum. for 4 ports divide the circum. by the width of the cutter, ours is .125″ so we can have 4 ports with a little wider than .125″ between for strenght. measure the port find its’ area x4 in this case it still would not flow enough. So hear is the beauty of the index wheel. Our stem dia. is .375 so it has a circum. of 1.178″. It has room for 9.4 index starting points, we use every other one. The portions between the ports are wider than the ports. To get a wider port index the work one inch furter around so you will remove more from one side of the ports, ( one inch is 1/48 of a turn, my wheel has a 48″ circum., valve stem has a circum. of 1.178″, divide the stem’s circum. by 48 you get .024 ) so the ports will now be .024″ wider than previous, if you think it will still not flow enough, index another one inch, or 1/2 inch or what ever your heart desires. just be carefull not to go too wide or the web between the ports will dissapear OOPS!! start again. Not like it has ever happened to me before, don’t get too greedy…


Here it is with ports cut to size plenty big. Velocity and air consumption will be adjusted by turning the valve stem closer or further from the valve seat. Our valve stems are stainless steel. Another point about having a large dia. index wheel is it gives you good leverage if you use it to turn the headstock and work to mill around the work as in cutting the loading port, easier than useing a wrench on the chuck’s jaws, what ever we have.

ya, combining the two is a great idea, i did it seperate ‘coz i had no way of putting the dressmakers tape on my disc brake. a narow tape? or have it divided up else where? just my spin

Maybe you could combine the two?

That is frigging cool! never thought of or seen the mill part on the tool post! I’ve seen people mount the tool in the chuck and mounting the work on the tool post…frigging ingenious! LOVE fluting work too! looks really cool.

Never thought of using the lathe as an indexer either that is a great idea as well. I chucked the valve in the lathe, held the chuck and free hand drilled the holes 😆 it was a PITA to say the least…never thought of locking down the chuck somehow 😆 man do I feel like a chimp about now LMAO…going to be making up an indexing ring and lockdown for my lathe ASAP!


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