Advice needed: Form turning

[n3480h]

I have a project coming up which requires four 1/2"Ø bullet shaped pieces. No, they are not bullets, but they are to have the form of the typical long range rifle bullet (just the bullet, not the case). I will be turning the brass on a manual HF 7x14 lathe. Can this be done with a radius turner (ball turning tool), or must I plot the form and repeat the thing four times? Or is there a better way?

I just KNOW someone is going to suggest .50 cal BMG bullets, but they must be brass.:think1:

Thanks for your help.

Tom

 

[DMS]

How long?

If the shape is not that important, a radius turning tool would probably work. If you have a specific shape in mind, you could get a piece of flat stock (O-1 works well), and cut/file out the profile you want. Harden it, temper it, then silver braze it to a shank to make a form tool.

I did this for some small brass thumbscrews I made a couple years ago, worked quite well.

 

[macrnr]

can you run a taper, or do they need a radius?

 

[mikey]

If they have to be identical then some device is needed. If they don't, then a graver will do it quickly.

 

[n3480h]

Thanks guys. I think a form tool would do nicely. I've made special groovers for o-ring grooves, this would just be a different shape. I think I can cut the tool on the mill, then harden it. Thanks for the help!

Tom

 

[n3480h]

Re: Advice needed: Form turning UPDATE

I got on the grinder and rough ground the profile I needed into a 5/16" HSS blank from LMS. Finish ground it with a Dremel mounted stone. Not the best tools for the job, but they worked. I roughed the shape in the brass with a conventional insert tool, then mounted the form tool. Right off the bat, the super sharp tool grabbed the brass slug, lol. Patience kicked in and feed speed lowered, and a slight reduction of tool sharpness, it went better. The tool worked better with a "slicing" feed motion rather than a direct feed into the brass. Took a while, but the piece finally contoured to the tool's shape. A little oil and 2,000 RPM provided a decent finish. Used 600 grade sandpaper, dry, still turning. Then 0000 steel wool for the finish you see here. I'll buff it for the final "blingification". Four of these will be used for tips on a biplane's javelins. Javelins mount where the wing wires form an X, and prevent vibration in the wires. Fun project and learned a lot about form tools and how brass cuts.

Tom