TANTALUM lathe/turning guide

so I come here sometimes over the years and have not contributed but have gained some info....so now its my turn to give back to other machine heads....I was going to respond to this old thread but it would resurrect an old 2009 thread

http://www.practicalmachinist.com/vb/general/tantalum-has-anyone-machined-176225/

so I am here to respond to this old thread of which little info can be obtained about the settings for machining TANTALUM. We all know the easiest way is wire EDM. Then secondly milling with a HS MILL at slow speeds with high feeds and coolant like trim-sol will even work....easy....but turning it is another matter...so I will give you some settings that have given me great success that was due to much trial and error....which should save anyone in the future some time and experimentation...as always these setting are not in stone and can be modified slightly....this was turning a 5/8 rod down to 10mm =/-.0015 by about 2 1/2 inches long....pure tantalum

TOOL BIT - 1/2 HSS square with SHARP POINT WITH HUGE RAKE...(chip should curl nicely or sharp point is gone and you need to regrind sharp) grind nice curl/rake on cutting edge to the point.

SPEED - 420 RPM

FEED - .0026 inches per revolution

DEPTH OF CUT - 0.01 total or .005 per side

COOLANT - thin film applied with acid brush of VACTRA #2 or similar oil (used MOLY-D cutting fluid also works good but don't like the fumes and possible toxidity)

FINISH CUT - same as above 0.01 worked really well for fine finish

final polish was with oil on part rubbed with 120 grit wet or dry emery paper at same speed above and just back and forth over finish maybe 8 times is all


well hope this helps you....and good luck if you modify my settings and maybe find a better way or coolant....if you do...post up what ya found like I did so we can all benefit....your gonna like these settings though


PS...I did this on a manual lathe and hand ground the bit....tried running it in a live tooling CNC lathe with no luck but was using a hand ground huge rake carbide NPR 50.1 and a 51 and a 52...tried em all...also ground those bits sharp and tried there kennemetal factory radius too.....no good...all broke...wore super quick

Tantalum is very expensive material. It is corrosion resistant material. I have swaged it and it formed easily enough. I think it is a very soft material.

Find a refractory metal distributor and see if he has some good numbers or a good contact to talk to about the S&F

TeflonDave said:

Tantalum is very expensive material. It is corrosion resistant material. I have swaged it and it formed easily enough. I think it is a very soft material.

Find a refractory metal distributor and see if he has some good numbers or a good contact to talk to about the S&F

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not sure what your trying to say....the speed is 420 and the feed .0026 per rev...made many pieces...very fine tolerance with 32 finish if you turn it to my specs...that's the crutch see....no refractory has that info...there is lack of info and a lot of trials and errors on line...like using mouthwash for coolant and all sorts of gimmicks....just use what I have above and you shall see...and from those settings you can deduce a smaller diameter or larger diameters speeds....the feed remains the same and the depth is always constant no matter what diameter....unless you use a larger toolbit with same rake....then you could go more depth but the .01 will make the toolbit last for many passes....if you try to increase the speed the tip wears off and the job tears....same for more feed or less feed....tearing...more depth usually breaks the bit and wears the tip off....so if you don't like grinding a bit every cut then just go with .01...I called kennemetal and have them looking into maybe making an NPR 50.1 HSS indexable tip since tantalum and niobium and many new materials will require this bit on CNC's for simplicity and savings and shops in the future will be needing these for these materials

...that's the crutch see....no refractory has that info...there is lack of info and a lot of trials and errors on line...

The area of expertise is a niche in the industry. I find good distributors, (salesmen) are a good start point to networking and eventually gaining more knowledge and understanding of a product. We have recently added tantalum to one of our products so thanks for the info you have laid out. I may need to machine it one day.
As with most processes that lack tried and proven points of reference there is an art of the tradesman that goes along with the science of gaining knowledge. So discussion with others helps to shore up your process or consider alternatives and modifications.

BTW Tantalum is used to make crucibles for laboratory experimentation and analysis.

VACTRA #2 for those of you that need to know is a way lube so any oil will probably work good....the key is to keep the tool point cool since tantalum is so abrasive...I tried acetone and that works good too but fumes could be an issue...also tried triple 1 triclorethane (sp?) and thats the best finish since it cools the tool super fast due to evaporation rate...acetone second best....tried trim-sol, not bad but tiny tears and tip only lasted 2 passes...will try other coolants but so far the vactra and that speed are holding a tight point on the parts shape which has tolerance of +/-.001 which is super hard to hit on tantalum.


also to achieve a good part after I cut the shape with the lathe....I cut the part off with a wire edm machine to hit the tolerance and a nice finish with a finished face for the next shape...then rub on a hockey puck stone to get the EDM doinker off and a flat face

ok a couple o updates....one is I didn't like the 120 rough paper needed a finer finish so went with 320....didn't work well...then went to 240 and just like heavy feed works so does the emery for finish and it doesn't take much off stock but I am using oil...I turned diameter to +.001 over to tweak it into size....then I had to face the rod...I had been using the wire edm which was super easy...so on the lathe to face every depth of cut tore except .003...even freakin rough facing it I just plucked along at .003 off each pass and it came out a 55/50ish finish then rubbed with emery to get to 32 finish...also during rubbing....LOL....I upped the RPM's to 800....for turning I then went down to 500 sometimes and sometimes 450 and 420...in that range only for cutting....have to sharpen tool a lot...parts coming out toot sweet

ok you can use this for VANADIUM and NIOBIUM and some other soft elements also...I will post up a pic of finished part when I get a chance....I have machined all these and made parts off these speeds and feeds that are a 32 finish and =/-.001

check out the knife edge on this baby in TANTALUM...virtually impossible...this job went to many places that said they could not do it...then it came to me....as they all do....LOL...I am proud o this it was super hard to get a good finish with a tolerance really close in essentially what is GUM....LOL

you have to be within .0003 when parting off or you wont get that diameter of the knife to within =/-.001

Johnny Larue said:

virtually impossible...this job went to many places that said they could not do it...then it came to me....as they all do....LOL...

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Its nice to see you don't have any sign of overinflated ego, humility as they say, is a virtue.

Did VWFullCup move to Indiana?

We have a new machining GOD in town.

Thy proclaims we will use hand ground HSS on ye manual lathe, 420 rpm and Vactra #2 whence cutting the ever mysterious TANTALUM.

Porschefix said:

Its nice to see you don't have any sign of overinflated ego, humility as they say, is a virtue.

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haha....just a ribbin'....this job went around America to many places and everyone passed said they couldn't do it....then it came to me and there they are babay....50 pcs too....wasn't easy at all...and the fellers read this too at me shop....we have an inside running joke aboot that...I won several contests the best machinist in America...then on one job...it went to seattle...and texas and east coast shops and all manners of shops...then to japan...then france....then England...finally 1 and 1/2 years later it came back to this shop...and the customer in front of everyone....(which we all had a good roar) said without skipping a beat....that I was the best machinist in the world and no one could do this job....(he had previously left saying it was costing too much after 2 years of working on it)....I told him he wouldn't be able to find anyone else that could do that tolerance on a pipe ( .005 wide simulated crack without breaking thru following the curve leaving a .003 wall on the inside WITHOUT breaking thru....100+ pipes)....so ya....I throw that at em once in awhile for fun...we joke around alot its good for moral and production...ole walts whistle while you work.....I see you guys here take everything SO seriously....its only machining...AND MACHINISTS LIVES MATTER....LOL

Me thinks you're trying to blow a lot of smoke. OK, you might get away with it at some of the shops you work at. Nice work, but nothing really that spectacular. I've seen a lot more impressive stuff over the years. Nope, the best guys that I've known over the years never had to blow smoke.
JR

This is a funny thread to me...not funny as in Ha Ha funny, but rather odd.
Johnny Larue has offered his expertise and experience in the hopes of helping other out.
Within a very few posts he's being jumped on, and within a very few more his techniques are being ridiculed.

Yes, I know, I know; he stuck out his tits a bit before we got to know him very well; but we ALL do that from time to time, even if just in our own secret hearts.
"Goddamn I'm GOOD" has probably crossed just about everyone's brain space at least once in their lives, so my vote is to cut him some slack, invite him on board, and welcome what he knows.

So welcome aboard Johnny.
Cheers

Marcus
Implant Mechanix • Design & Innovation > HOME
www.vancouverwireedm.com
Clarus Microtech Inc. | Facebook

implmex said:

This is a funny thread to me...not funny as in Ha Ha funny, but rather odd.
Johnny Larue has offered his expertise and experience in the hopes of helping other out.
Within a very few posts he's being jumped on, and within a very few more his techniques are being ridiculed.

Yes, I know, I know; he stuck out his tits a bit before we got to know him very well; but we ALL do that from time to time, even if just in our own secret hearts.
"Goddamn I'm GOOD" has probably crossed just about everyone's brain space at least once in their lives, so my vote is to cut him some slack, invite him on board, and welcome what he knows.

So welcome aboard Johnny.
Cheers

Marcus
Implant Mechanix • Design & Innovation > HOME
www.vancouverwireedm.com
Clarus Microtech Inc. | Facebook

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Marcus, I've worked a lot of tantalum and niobium. They are metals that have my respect re: machining, stoning, edm'ing and polishing. For a lot of reasons they require a completely different approach. Johnny has gone into some of the important aspects, some I agree with, some, meh. I agree it is interesting for those who have not worked with or frustrated by working with tantalum, it can be a bear!
However,
Boasting turns me off more than anything. No matter whether the person has the right to brag or not, I'll not stay within earshot of someone who feels the need to tell others that they are better than me, or you, or anyone. The best machinists I've ever known have never told me how damn good they are, their work shows how damn good they are, heck that goes with all walks of life.
Then, the op comes back and plays it off like its some big joke that everyone else he knows is in on, except for the readers of this forum, and then berates us for being so serious.
I have nothing against talent, I learn from these guys on here ever day.

Oh, Thank you JL for the information you've shared and welcome to PM.

Johnny Larue said:

you have to be within .0003 when parting off or you wont get that diameter of the knife to within =/-.001

View attachment 176309View attachment 176310

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.0003 with a wire edm.. the horror!

Porschefix said:

Marcus, I've worked a lot of tantalum and niobium. They are metals that have my respect re: machining, stoning, edm'ing and polishing. For a lot of reasons they require a completely different approach. Johnny has gone into some of the important aspects, some I agree with, some, meh. I agree it is interesting for those who have not worked with or frustrated by working with tantalum, it can be a bear!
However,
Boasting turns me off more than anything. No matter whether the person has the right to brag or not, I'll not stay within earshot of someone who feels the need to tell others that they are better than me, or you, or anyone. The best machinists I've ever known have never told me how damn good they are, their work shows how damn good they are, heck that goes with all walks of life.
Then, the op comes back and plays it off like its some big joke that everyone else he knows is in on, except for the readers of this forum, and then berates us for being so serious.
I have nothing against talent, I learn from these guys on here ever day.

Oh, Thank you JL for the information you've shared and welcome to PM.

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I have earned the right to brag or chest pump alittle and rib sometimes...i'll make it short...my parts were in an IMAX FILM...I was chosen out of all the machinists to make the TEMPLATE FOR THE COSTAR for hubble telescope...the template had to be flawless or everyone of you would know my name today if it failed....I run a hardinge SP slant bed chucker with live tooling and 5 places...not many machines were 5 places then.....maybe 6 lathes at that time...so huge pressure was on....that math had been checked by 19 JPL scientists and all manners of people and experts...I told them all that the math was wrong...they threatened do it this way or else...I said hubble will be flawed again then...I said how about this...I correct the math and then you check again on super computer or who ever and if its wrong I will quit...if its right how ever I want to run this place for 90 days...guess what...I was right...it was off again...they did not use a TRUE ELIPSE but rather nurbs or some shit...so I adjusted the numbers of the hubbles telescope corrective space lens and my ASS was riding on a solid rocket booster.....literally...I also repair the 3 gyro's and the titanium threaded pins for the doors as well since I said I could do it all perfect...they put it all on me...guess what...we now know that hubble can see FARTHER then they ever expected...and I was given carte blanche since then to brag I'm the best...and right after that...the mars rover came in after it was tested in that sandy place here...I tweaked the axles and cleaned the wheels and axles to within .0001...guess what...they say....we don't understand why its still going and rolling after all these years...me baby....me....so yes...I have put MY MONEY WERE MY MOUTH IS as you say PORCHEFIX...and thanx fer the welcome dude

PS...HUBBLE (imax0 watch it...really neat

Johnny Larue said:

I have earned the right to brag or chest pump alittle and rib sometimes...i'll make it short...my parts were in an IMAX FILM...I was chosen out of all the machinists to make the TEMPLATE FOR THE COSTAR for hubble telescope...the template had to be flawless or everyone of you would know my name today if it failed....I run a hardinge SP slant bed chucker with live tooling and 5 places...not many machines were 5 places then.....maybe 6 lathes at that time...so huge pressure was on....that math had been checked by 19 JPL scientists and all manners of people and experts...I told them all that the math was wrong...they threatened do it this way or else...I said hubble will be flawed again then...I said how about this...I correct the math and then you check again on super computer or who ever and if its wrong I will quit...if its right how ever I want to run this place for 90 days...guess what...I was right...it was off again...they did not use a TRUE ELIPSE but rather nurbs or some shit...so I adjusted the numbers of the hubbles telescope corrective space lens and my ASS was riding on a solid rocket booster.....literally...I also repair the 3 gyro's and the titanium threaded pins for the doors as well since I said I could do it all perfect...they put it all on me...guess what...we now know that hubble can see FARTHER then they ever expected...and I was given carte blanche since then to brag I'm the best...and right after that...the mars rover came in after it was tested in that sandy place here...I tweaked the axles and cleaned the wheels and axles to within .0001...guess what...they say....we don't understand why its still going and rolling after all these years...me baby....me....so yes...I have put MY MONEY WERE MY MOUTH IS as you say PORCHEFIX...and thanx fer the welcome dude

PS...HUBBLE (imax0 watch it...really neat

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Corrected the math that was checked by 19 scientists...adjusted the lens on hubble...
I thought he was just a troll. Sounds more like a compulsive liar now.

I like his style.....pics or it didn't happen . I though the best shape for telescope main mirrors was the paraboloid unless you start using a corrector lens like in Maksutov telescope.