Indexing on lathe

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.

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.

http://i245.photobucket.com/albums/gg54/camotes2/IMG_0129.jpg

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?

http://i245.photobucket.com/albums/gg54/camotes2/IMG_0128.jpg

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…

http://i245.photobucket.com/albums/gg54/camotes2/IMG_0131.jpg

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.