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Thread: Making titanium pens
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3rd Sep 2018, 07:25 PM #1Most Valued Member
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Making titanium pens
I've ordered some titanium solid round in 8 and 10mm with the intention of trying my hand at making a few pens as give-aways. I think the pieces I've ordered are of the better grades for machining (6-4 and 3-2.5). I have plenty of carbide tooling, so I'm not too concerned about turning the outside of the pens. However, I am concerned about drilling the hole through the pen. I'm going to use a D1 pen refill which is 2.3mm in diameter and 67mm long.
My proposed design is a straight-sided pen with a screw-on cap. It would be drilled to take the D1 refill. The end would be drilled and tapped to take a brass tip that holds the refill in place and provides something for the cap to slip or screw onto. Something like this:
Ti pen.png
I believe heat build-up is the main problem with Ti as it has only one quarter of the thermal conductivity of steel. I don't have flood coolant.
I've got some Q's I hope someone can answer:
- Before I destroy a bunch of HSS drill bits, should I bite the bullet and get solid carbide drill bits for the job?
- Any precautions required when using taps?
- Any other tips for working with Ti on a small lathe (Hercus 260)?
Cheers,
ChrisChris
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3rd Sep 2018, 07:46 PM #2
Hi Chris,
I've never worked with Titanium either But I would definitely go with carbide tooling, both drills and taps. I understand that it is a very tough material, a bit like stainless steel. I don't know what lubricant you might need for machining, but I feel that you will need something.
JMTPW.Best Regards:
Baron J.
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3rd Sep 2018, 08:05 PM #3Senior Member
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Perhaps a gun drill? My concern for the drill material is secondary to your chances of getting that hole to be remotely straight, especially when youll struggled to keep a hss drill sharp for that length of hole. A gun drill with a carbide tip would have a much better chance of making it down the other end with anything resembling straightness.
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3rd Sep 2018, 09:16 PM #4Most Valued Member
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Thanks gents. Gun drills seem to be exy. Another option might be to drill 5mm all the way using one of these:
https://www.amazon.com/gp/product/B0...KIKX0DER&psc=1
5mm is the tapping drill for a M6 tap. The price is right.Chris
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3rd Sep 2018, 10:38 PM #5
Hi Chris,
Titanium can be worked on Sherline lathes, so your Hercus should be fine.
The material work hardens so speeds and feeds are important. It also galls (like aluminium and stainless).
A 67mm deep hole for a 2.3mm drill is nearly 30 times diameter deep. It's still over 10 x deeper than a 5.0mm drill. Whatever drill you buy, make sure it is rated for that depth of hole. A Cobalt drill with parabolic flutes might well also do the trick.
Cheers
The Beryl BlokeEquipmenter.... Projects I own
Lathes - Sherline 4410 CNC
Mills - Deckel FP2LB, Hardinge TM-UM, Sherline 2000 CNC.
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4th Sep 2018, 12:54 AM #6
Hi Chris, Guys,
That carbide drill looks to be very good value ! It would be at least double that price here from MSC.Best Regards:
Baron J.
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4th Sep 2018, 02:13 AM #7Most Valued Member
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4th Sep 2018, 06:57 AM #8Most Valued Member
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An aeroplane is my next project. I have a thread engagement chart too. I’ll have a look. I hate the feel of sloppy threads though. They don’t scream “quality” to me. The treaded part will only be about 10mm deep so I can always open that up a bit with my small boring bar. Good point though.
Chris
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4th Sep 2018, 09:14 AM #9Most Valued Member
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I second the suggestion of a lower percentage of thread engagement. The feeling of slackness doesn't really come so much from the engagement but the thread form anyway. 60% you just won't notice, except you'll be able to see the threads clearly because there won't be a snapped tap jammed in the hole.
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4th Sep 2018, 10:01 AM #10Senior Member
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I won't comment on the threading, but will give some hard earned pointers on machining titanium on a taig lathe.
keep your tool tip clean and sharp - with a boring bar or turning tool I would take two passes, then use a small slip stone to take the galling Ti off the HSS tip, then 2 more passes, swipe, etc - I got lazy and complacent once and on the 4th pass there was a small puff of white smoke, and the tip of the HSS cutter had melted away.
when I was drilling, I used trefolex as lube, and peck drilled. in my case it was 1/4" holes through 20mm thick slices of Ti (from bolts) which I then bored out to ring sizes.
all of my tools (cutters, drills, etc) were HSS, and as long as the buildup on the cutting face was removed, they worked fine, and did not blunten
Des
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4th Sep 2018, 04:43 PM #11Most Valued Member
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In another life in aircraft structural maintenance I drilled and reamed quite a lot of titanium - both fasteners and structural components/fittings. We generally used 120deg split point HSS cobalt drills in hand held pneumatic drills, and the reamers were just straight flute HSS machine reamers. Never had to drill any really deep ones, but often around 5x diameter to take splined screw extractors
As others have said the key is to keep the tool cutting, and with the air drills if you eased off the feed pressure too much and let the RPM get out of control they would spin, work harden, and burn the edges off the drill bit or reamer.
We used either Trefolex or Rocol as a cutting compound. If the tool starts to get dull sharpen or change it.
Steve
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4th Sep 2018, 07:00 PM #12
I know it has been suggested to use trefolex which in my experience is a paste. So this may not be required. If you wanted to do a drip or flood coolant you can always set up a temporary diy drip feed coolant with a upside down hanging 2lt soft drink bottle with a hole drilled in the cap and a hose attached. Poke a hole in the base (which will be the top when inverted) and enlarge until you get the desired flow rate.
…..Live a Quiet Life & Work with your Hands
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4th Sep 2018, 11:06 PM #13China
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Trefolex is also available as thick fluid
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5th Sep 2018, 12:42 AM #14
Hi Guys,
The tin of Trefolex that I have is a bit like thick grease ! But it takes very little heat to melt it into a thin oily liquid.
If I remember correctly, it is basically a mixture of lard and sulphur with some other stuff mixed in.
It is amazingly effective on taps and when drilling holes, particularly deep ones. I also use it on my hacksaw blades, that is when you most notice the reduction in effort.
My tin must be well over twenty years old by now, and if I spotted a new tin for sale I would buy it tomorrow.
I've got a can of Rocol RTD, I'm not keen about it, it also stains, which I don't like.Best Regards:
Baron J.
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5th Sep 2018, 01:32 AM #15Most Valued Member
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Thanks for the replies all. I have Trefolex in paste, liquid and spray can forms.
Des’s post has got me thinking that Crobalt might work well on Ti. My diamond tool holder with a crobalt cutting tool cuts SS like butter.Chris
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