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Titanium or SS?

SmokeWalker

Plastic
Joined
Aug 26, 2014
Location
United States
Hey Everybody,



I've got a potential job coming up and I'm trying to decide between Gr. 2 Ti or SS. We don't need the strength of Grade 5, and the part needs corrosion resistance, so some economical stainless steel would be required if going with anything ferrous.



Machinery:

Manual chucker lathe with the option of low pressure through coolant drill usage.



The part will have a 3/8" hole either drilled 7xd.

The part will have bores to accommodate 9/16-40 internal multistart threads that go 1/2" into the part.

Run of maybe 100 pieces.



Help me decide which material to go with. The main concern with Gr. 2 titanium is that even with the sharpest of tools, and perfect chip formation, I've seen it kick up super small burrs with forming cuts, so I'm worried about burrs at the thread crest which could make the fitment of the parts go all over the place. I can totally see inconsistent thread quality being an issue here, as the multistart threads have to be cut one lead at a time. It's manual, so we can't index for each lead, it would take too long. I thought about cutting the threads for each lead one at a time, and then doing a spring pass–after the part is "roughed out" essentially–to remove any burrs. What do you think? Also, I thought it might help to start with a minor diameter that's a bit bigger than usual. This is for a part that's usually done in plastic, and switching to metal means less <thread %> will be necessary.



What do you think?



SW
 
Re price of Ti - this is the only online priced source I know - it ain't cheap :eek: Bar - Titanium Joe


An aside - a few years back a trackday biker wanted me to make him a set of footpegs and linkages for his crotchrocket organ donor, had it all drawn out in CAD etc etc but it HAD to be in Ti - nothing else would do, ……..so I told him - you supply the material - here's a source (TiJoes url) and I'll machine it for £x.
At which he exclaimed - that's a lot of money to which I answered ''wait till you see what the materials going to cost you.''

Epilogue; Some Alu and 303 SS was found to be perfectly adequate.
 
Ti is expensive. Plus it also gals very easy. if you have parts threading or sliding into each other, it wont be long before there locked together
 
9/16-40 multistart thread?

and the material options being Ti or _cheap_ stainless steel? at least here, Ti on average is 4 or 5 times more expensive than the "expensive" 316 stainless...

this "problem" sounds just weird
 
Ti is a bitch to machine. Hard as woodpecker lips. My boss brought me a Ti rotor from a centrifuge and wanted me to bore it out and mount it on a walnut stand . His idea was to put a nice clock movement in it and have an engraved plate mounted on the walnut as a retirement gift for one of the uppity ups. I did it, but never again unless I absolutely have to.
 
Absolutely go with stainless if cost is a factor. Titanium can be machined just like most any other material but it definitely takes more time than stainless.
 








 
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