Tapping titanium-what am I doing wrong?

elkins45

elkins45

Joined
Jun 17, 2006
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I wanted to move the clip on my titanium frame lock (Benchmade 750). The factory clip is screwed into tapped bushings that are inset into the titanium handle. My plan was to tap the titanium and screw directly into the scale. I think now I understand why they used the bushings!

I bought the correct 2-56 tap and used a #50 bit for hole just like the guides say. I used a cutting fluid, worked slowly and backed the tap out to clear the chips...and snapped it off with not much effort at all. I managed to get the broken stub out the first time, but when I tried to finish the hole it snapped off again, this time too low to remove. Now I have a knife with a tap stub stuck in the handle. It's flush with the handle, so it's still functional but it's ugly.

What am I doing wrong? And is there a way to get the tap stub out of the hole?

TIA for any advice.
 
I can't give you advice, but I do know Ti can be very gummy when tapping or machining and really likes to bind up the taps. There's a bunch of guys who work in titanium on a regular basis that should be able to help you out.

--nathan
 
When ever I break a tap in Ti, I place the part with the broken tap in Ferric Chloride overnight. Next morning the tap is pretty much dissolved, and anything that's let can be easily cleaned out with the size drill bit used to drill the original hole.

Speaking of holes....when I tap titanium, I always use one size larger drill bit than what the charts call for. What you have to remember is that those charts are based on 75% thread, in mild steel. If you try that with Ti, you generally will end up with a broken tap. When I thread 2-56 in Ti, I use a #49, or if the Ti is more than .100 thick, at #48. Don't worry, theres plenty of thread to hold.
 
i dont tap any 2-56 in ti thicker then .065
thicker then that and i drill with a larger bit to make the taped part .070or less
the larger bit need not be more then 2 # bits bigger

also what i hear is a big help is a tapping jig

oo you are using good tappping lube right ?
 
I now use a thread forming tap from Enco and/or Balax taps via MSC Industrial Supply and a number 47 drill bit for 2-56 in titanium. Today I threaded 15 holes in .160 titanium frame lock sides and two in .050 thickness titanium on one of them for the non lock side no problem at all. For years I've used a number 48 in titanium and just recently after some tap problems with breaking suddenly a bunch in a row I spent a great deal of time researching this. A Balax tap design engineer suggested I use a #47 drill and thread forming taps in titanium and to ignore the books and what they call for with a #50 which I already knew due to how titanium hugs or galls to things the way it does. I noted early on that titanium seems to hug things the deeper they go. Taps are a good example of this. Brian Fellhoulter uses a 5/64 drill for his thread forming tap in this size. That is actually right between the #47 and the #48 drill size.

Believe me I've extensively tested the #47 using the thread forming taps and the threads hold. No worries on thinner material either but I still use a #50 on softer materials and a #48 on other thinner metals but for anything .050 or more I use the #47 now for all of it. Molly Dee lube or the Dry Lube from TapMatic both work well for me.

STR
 
Ed Caffrey said:
When ever I break a tap in Ti, I place the part with the broken tap in Ferric Chloride overnight. Next morning the tap is pretty much dissolved, and anything that's let can be easily cleaned out with the size drill bit used to drill the original hole.

Speaking of holes....when I tap titanium, I always use one size larger drill bit than what the charts call for. What you have to remember is that those charts are based on 75% thread, in mild steel. If you try that with Ti, you generally will end up with a broken tap. When I thread 2-56 in Ti, I use a #49, or if the Ti is more than .100 thick, at #48. Don't worry, theres plenty of thread to hold.
Click to expand...

Exactly as i do!! i tap alot of 3/16" TI for 2-56!! really you only need 50/60 thou of threads, so if the TI is thick run a clearance drill in part way.
 
Ed Caffrey said:
When ever I break a tap in Ti, I place the part with the broken tap in Ferric Chloride overnight. Next morning the tap is pretty much dissolved, and anything that's let can be easily cleaned out with the size drill bit used to drill the original hole.

Speaking of holes....when I tap titanium, I always use one size larger drill bit than what the charts call for. What you have to remember is that those charts are based on 75% thread, in mild steel. If you try that with Ti, you generally will end up with a broken tap. When I thread 2-56 in Ti, I use a #49, or if the Ti is more than .100 thick, at #48. Don't worry, theres plenty of thread to hold.
Click to expand...

Thanks to everyone foe the good advice. Where can I find some ferric chloride?
 
One or two sizes larger drill works great for ti. I stopped breaking taps when I started using a elec drill/driver to run the taps. Zip em in, zip em out, fast and no breaking. I use mostly 0-80 and we all know how easy they break
 
elkins45 said:
Thanks to everyone foe the good advice. Where can I find some ferric chloride?
Click to expand...

Radio Shack PCB Board etchant, cheap and easy.

With small taps, I use Tetra lube. It is slicker than greased glass, and I have a bottle laying around.

Chuck
 
This is a great thread. I have been banging my head against the wall, tapping .125 Ti... and even with a Tapmatic and tapping fluid, I am busting tap after tap. The through holes were 49, so I will try the 47. I love Bladeforums- a quick search and problem solved!
 
This thread is a gift from heaven as I was (attempting) to tap 1-72 blind holes in .160 Ti last night, with frustrating results. The ferric cloride idea could probably help me salvage some handles that now have broken taps in them. Thank you.
However, being european, I may have used an incorrect size drill, unfamiliar as I am with US drill and tap sizes. I measured the 1-72 screws to 1,8mm and decided to use a 1,4mm drill for the holes, based on experience with 2mm screws in the same material. Could anyone please direct me to an online chart?

Brian
 
Gody said:
This thread is a gift from heaven as I was (attempting) to tap 1-72 blind holes in .160 Ti last night, with frustrating results. The ferric cloride idea could probably help me salvage some handles that now have broken taps in them. Thank you.
However, being european, I may have used an incorrect size drill, unfamiliar as I am with US drill and tap sizes. I measured the 1-72 screws to 1,8mm and decided to use a 1,4mm drill for the holes, based on experience with 2mm screws in the same material. Could anyone please direct me to an online chart?

Brian
Click to expand...

Google will get you dozens of tap charts and conversion charts

There is a calculation that will work with metric and inch, but especially in those small sizes, you will likely need to buy #ed drills
http://shopswarf.orconhosting.net.nz/drills.html
http://www.csgnetwork.com/screwnummachtable.html


You're drilling too small.

recommended
1-72 NF #53 0.0595" 1.5113mm

You might get away with a 1.6mm drill
do some testing on scrap

Others here have recommended thread rolling taps instead of cutting in titanium, but the drill sizes used are different than cutting.
 
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OSG thread forming taps work well for this. You can get then from MSC. Molydee helps too. You can run 2-56 through 1/4" of 6-4 in one whack.
 
I have discovered that using a hand tapper lessens (for me) the incidences of breakage. My small hand tapper, for diameters of 6mm or less, is made by Cedarberg Industries. The height clearance is 9cm and the throat depth is 11.5cm. My tap drill choices are determined by the ratio of the hole depth to the hole diameter. See the Machinery Handbook class of fit tables. The style of tap that I use doesn't seem to matter. I use Tap Magic cutting fluid. If I break a tap, I dissolve it with battery acid (29-32% H2SO4). I have tapped #0X80TPI into 1/8" 6-4 Titanium. I do a lot of #2X56TPI, 2.5mmX.45mmPT, and #5X40TPI in Titanium. I don't understand the threaded steel inserts that Benchmade puts in their Titanium handles, but it makes perfect sense in the Carbon fiber sideplates.
 
12345678910 said:
Google will get you dozens of tap charts and conversion charts

There is a calculation that will work with metric and inch, but especially in those small sizes, you will likely need to buy #ed drills
http://shopswarf.orconhosting.net.nz/drills.html
http://www.csgnetwork.com/screwnummachtable.html


You're drilling too small.

recommended
1-72 NF #53 0.0595" 1.5113mm

You might get away with a 1.6mm drill
do some testing on scrap

Others here have recommended thread rolling taps instead of cutting in titanium, but the drill sizes used are different than cutting.
Click to expand...

Thanks. This is exactly what I was looking for.

Brian
 
Awesome stuff guys, thanks. Four years later, right on the money.
 
elkins45 said:
I wanted to move the clip on my titanium frame lock (Benchmade 750). The factory clip is screwed into tapped bushings that are inset into the titanium handle. My plan was to tap the titanium and screw directly into the scale. I think now I understand why they used the bushings!

I bought the correct 2-56 tap and used a #50 bit for hole just like the guides say. I used a cutting fluid, worked slowly and backed the tap out to clear the chips...and snapped it off with not much effort at all. I managed to get the broken stub out the first time, but when I tried to finish the hole it snapped off again, this time too low to remove. Now I have a knife with a tap stub stuck in the handle. It's flush with the handle, so it's still functional but it's ugly.

What am I doing wrong? And is there a way to get the tap stub out of the hole?

TIA for any advice.
Click to expand...

My friend who has been working with titanium for years says this ..........once you start tapping don't backup or stop until you have full thread .And used tap specifically designed for titanium......
 
I've been using #48 for the last couple of years and never had any issues once I purchased a Tapmatic... that was up until last week I snapped 2 2-56 OSG thread forming taps on the same hole within a couple of days. This was after the frame sat in FC to dissolve the 1st one i broke. As I was searching for new taps I ran across this thread and glad i did..... Since you haven't had any issues with a #47 I think i will give that a s shot now and hopefully my broken tap days are a thing of the past again......Thanks for sharing....


STR said:
I now use a thread forming tap from Enco and/or Balax taps via MSC Industrial Supply and a number 47 drill bit for 2-56 in titanium. Today I threaded 15 holes in .160 titanium frame lock sides and two in .050 thickness titanium on one of them for the non lock side no problem at all. For years I've used a number 48 in titanium and just recently after some tap problems with breaking suddenly a bunch in a row I spent a great deal of time researching this. A Balax tap design engineer suggested I use a #47 drill and thread forming taps in titanium and to ignore the books and what they call for with a #50 which I already knew due to how titanium hugs or galls to things the way it does. I noted early on that titanium seems to hug things the deeper they go. Taps are a good example of this. Brian Fellhoulter uses a 5/64 drill for his thread forming tap in this size. That is actually right between the #47 and the #48 drill size.

Believe me I've extensively tested the #47 using the thread forming taps and the threads hold. No worries on thinner material either but I still use a #50 on softer materials and a #48 on other thinner metals but for anything .050 or more I use the #47 now for all of it. Molly Dee lube or the Dry Lube from TapMatic both work well for me.

STR
Click to expand...
 
Last edited:
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