Morning all, I'm not able to successfully cut external cycle threads in stainless steel bar - mostly 3/8". I'm not using cheap Chinese dies, I'm using what I thought would be good quality HSS items from Tracy Tools, and I have a proper quality British made die stock. Despite opening out the split dies to the fullest extent, using cutting fluid and going as slowly and carefully as I can, I still end up with poor definition threads. They look terrible and they pick up on the nuts. I've used the die 20-30 times maximum, so it's disappointing if it's already worn out. Any suggestions/advice would be greatly appreciated. Cheers.
Hi,
Do what you're doing plus turn the die a few degrees clockwise before anticlockwise to break the swarf, lots of stainless cutting lubricant, clean the die regularly, use 303 stainless and change the die often.
Or:
Give up like I did and buy the bar already threaded.
Best wishes...
Hi Bess, Thanks for you response and advice, it sounds like even the better quality dies don't last more than a few minutes! So as you say, it's probably more cost-effective and certainly less frustrating to buy the damn things! All the best.
SS is a pig to machine at the best of times and one of the problems is that it work hardens not only blunting cutting tools but also making it hard to break off the chips produced. Best to avoid machining it if possible. I try to steer well clear of it on my lathe!
303 or 304 is easy enough to machine either with HSS or carbide tooling but don't touch 316 that's a marine grade and needs industrial machines and tooling. Don't bother with taps and dies described as carbon steel they are rubbish, buy HSS from a good supplier like Tracy tools, I know they are more expensive but the quality is there.
Thanks all for your advice. Even though I'm using HSS dies from Tracy Tools it's still a problem, so I guess I'll have to do as Bess suggests: give up and buy the bloody things - very disappointing. Thanks again everybody.
Stainless steel doesn't cut very well with standard hand dies. It needs carbide tools and a big powerful lathe . I once tried to cut a thread on an A4 marine grade fitting and my HSS 1" die snapped with a hell of a bang, after I checked to make sure I wasn't full of shrapnel I gave up and Google was my friend.
Thanks Bob. Just confirming what everybody says and what I've discovered sadly. Cheers.
Grade 303 is fine for machining on the lathe, here's one I made earlier.
Geoff - I cut these today, it was hard to start off but once it got started it was ok. 304 grade