Stainless Steel Thread Bar & Insert

[dabigguy]

What is everyone using out there for single point threading internal threads less than 1/2 diameter hole ie. 1/8 NPT, 1/4 NPT, 7/16-20, 1/2-20. We use a Carmex SIR 0265 K08 which works good for aluminum, brass and steel but insert does not last long in stainless. Yes I have plenty of coolant, newer machines and all the other obvious things before they are mentioned. I far as know there is only one grade of insert in the size needed for that bar. Thanx.

[tawlathes]

all most any c axis lathe can theard mill first choist
tap is the next best
and a theard bar if you must

[gcodeguy]

I don't know how many grades are offered in that size to be honest. We've always used the BXC grade. Suggested SFM for SS is 100-300. Usually you can't run very fast anyway because of chatter. I've pretty much given up on single pointing any pipe threads under 3/8 inch in 316 SS as we lose too many parts. No place for the chips to go, and the threading insert keeps chipping. For some reason the 7/16-20 seems to run pretty good.

Be sure to post back if you find something that does work better. I'd be interested in knowing what you found to work the best.

[Cuda]

We tap anything smaller than 5/8 thread, and 1/4" pipe is the biggest we tap, everything else is done with Vardex laydown threading tools Grade VM7 seems to work great in 304 and 316 SS, we always use a rougher tool to get most of the stock out and then use a finish tool to take the last .010 out. Light cuts seem to hold up the best for roughing and speeds of 150/300 FPM depending on depth. And a trick is using just the first clamp screw to hold in the bar often cuts down on chatter when threading. Vardex does make tooling for smaller stuff.
http://www.vardexusa.com/vardex-threading.aspx

[SDConcepts]

i second using vardex in 304, 316, 321 ss. but really all those small threads like you described we tap.

[Spinit]

Solid carbide Micro 100 type threaders work well for us. Micro 100's are very expensive and so we use also IT tools. If I ever get to run a job soon on my favorite lathe I would be grateful to even thread some harder metal.

[gcodeguy]

Originally Posted by Spinit

Solid carbide Micro 100 type threaders work well for us. Micro 100's are very expensive and so we use also IT tools. If I ever get to run a job soon on my favorite lathe I would be grateful to even thread some harder metal.

Yeah, times suck right now, don't they? We no longer use Micro 100 because of their prices.

[Diesinker]

I use Vardex and Scientific for ID threading on all our swiss turns and Mazaks.