This Miserable Titanium

Erin Burke

Erin Burke

KnifeMaker...ish
Joined
May 19, 2003
Messages
1,330
Hey all,
I am attempting to make my first non-fixed blade knife (Knife #13), a sweet little balisong based on a design I did earlier. Below is a rough CAD sketch.

5011405905_8d12b0bdbd_o.jpg



This will be my first time working with titanium. I have a plate of 0.13" 6AL-4V and have already had a bunch of fun drilling 1/8" & 3/16" holes to screw it tight to my "fixture plate". Base on this initial experience I now have a number of questions:

  1. Do I have to use a "very hard" material for the fixture/backing plate to avoid binding the bit as it comes out the back side of the Ti? Currently I have a scrap of African Padouk (hardwood) that I milled flat. I have broken a couple of 1/8" bits as they exited the Ti. I'm not sure if this is the fault of my backer material or the crappy bulk HF bits that I was using. Also, the Ti plate may have been less than perfectly RIGID since I was in the process of drilling holes to mount it to the fixture plate. I can post photos later.
  2. What type of bits do you use for drilling Ti? Like I said, I tried some cheap HF 1/8" bits and they chattered and broke... maybe crappy bits, maybe crappy speed/pressure/rigidity. I have heard many folks recommend cobalt bits. Seems like this may be something to buy in bulk... what bits do you buy and where do you buy them? Any recommendations on point angle?
  3. What speeds do you use for drilling 6AL-4V? Based on the link that I found HERE, I should be using 20-30SFPM or 611-916rpm with an 1/8" HSS bit. Does this seem about right? This gives me 407-611rpm for a 3/16" bit. I have a VS small mill, so I should be able to play with the speeds a bit.
  4. I have heard that you need to keep pressure on the bit when drilling Ti. If my bits are "chattering", is this a sign that I may be putting TOO MUCH pressure on the 1/8" bit?
  5. How many of y'all are using flood coolant when drilling your Ti? This is not something that I have set up on my mill... do I need to come up with something?
  6. How about reaming holes in Ti? I've been told a good rule of thumb for reaming is "half-the-speed, twice-the-feed" used when drilling the hole. However, THIS TABLE that I found on the internet seems to indicate that the speed should be faster for reaming Ti than for drilling (as seen in the previous table). Any recommendations for SFPM for reaming?
  7. Lastly - and this is just a general milling question - if I am drilling/reaming a screw hole that will also have a counter-bored area for the screw head should I:
    1. Drill the hole first then create the counterbore with an end-mill or
    2. Use the end-mill first, then drill the center thru-hole for the screw.
    This assumes that I have to use an end-mill because I do not have a piloted counterbore that fits.
What I'm really trying to do is get the most life out of my drills while producing a clean hole. I am not in a hurry, and want to do things right. I'm sure I'll have more questions as the project progresses. Thanks in advance.
Erin
 
I went through HF bits like crazy drilling some Ti and stainless. Finally I bought a cheap set of cobalt bits on ebay for $15 and they blow the HF bits away. I can only imagine what a good set of cobalt bits would be like. I also bought some carbide endmills and find they drill very nicely through carbide that's bolted down well. If it's not in a vise on the drill press don't try it though.
 
For drilling Ti I use cobalt bits from enco,Made in USA brand.Your speed are about right and I use rapid tap as a cutting fluid.Use sharp bits with a 135 deg point.
I drill my holes then counterbore with an endmill.
Stan
 
Answers to your questions.

1) A solid fixture helps exponentially. No movement from the part or the fixture assures the later guesswork as to what went wrong.
2) I have used Cleveland twist with great success. 118 deg point worked for my application many times over. General rule with Ti- Don't play with it, take a cut with sharp, new bits. If you mess up too much on the feeds and speeds you could very well work harden it. This is where most breakage occurs. Most towns have an industrial supply...Check there for bit availability.
3) I have gone a bit higher with the surface footage. I believe at 50 worked well for me in CP2.
4) Chatter generally indicates that your spindle speed is too high....Either drop spindle speed or increase the feedrate.
5)I use flood coolant...It helps me...Not sure what else to add..
6) Reaming Ti is not all that difficult to understand. Generally speaking...There are more flutes to account for...So cutting your speed and doubling your speed seems to fit my strategies for reaming Ti. You are not taking a significant amount of material in this operation, so you have some room for error here.
7)Drill first and follow up with the endmill. Helps to keep wear and tear off of the more expensive of the two tools by not forcing the endmill to centercut when that really isn't the endmills strong point.
8) That bali ROCKS! Love the design!

Keep in mind, my experience with Ti is CP2 (commercially pure) in a prototype environment, although I have run some production runs on this stuff ( and have some laying around for future projects :)

Bill
 
It's not a question of teaching titanium who is boss. It's a matter of sneaking up on it and imposing your will without it discovering that it's lost its own will. Titanium will never acknowledge you as the boss, but you can have your way with it.
 
Raymond Richard said:
Erin, Ever thought of using wrought iron. Antiqued maybe? It sure works nice.
Click to expand...

Heh heh... That sounds like something Ray Richard would do. ;) Maybe use some rebar for the blade. :p

I carry a nice little Benchmade 42mc in my right pants pocket and really like the reduced weight of the titanium handles. I'd just like to carry something that I made myself instead.

BTW, I'm planning to bend my own Ti pocket clip for this knife too (though it's not shown on the sketch).

Don't worry... I don't plan on making a habit of these folding thingys. Not yet.
 
Thanks to all the folks who offered advice... I'm now drilling Ti like a dream. This is what I did:

  1. Finished securing the 0.13" Ti plate down to the backing plate. I believe the rigidity helped a lot.
  2. I bought a TON of made in USA cobalt bits from MSC. They were having a 35% off sale. I figured that I might chew through a few bits on this project so I bought a dozen or so bits in 3/32", #31, 1/8", #14 and even a few #29 bits.
  3. I adjusted my cutting speed to 20sfpm... which is the low end of what was given in the table linked in the OP.
  4. I peck at the holes... three pecks (with firm pressure) and I'm through... no fuss. I use a brush on the spinning bit to remove chip coils between pecks.
  5. No cutting fluid. I do not have a flood coolant system, but alot of times I'll use a little Kobalt cutting fluid in the holes as I'm drilling steel. This Ti does NOT like this. Likely I have much to learn concerning the differences between "cutting fluid", "cutting lubricant" and "coolant"... but for this project I'm drilling them dry.
Results?... I've drilled all of my 3/32" holes and most of my #31 holes (close to 40 holes so far) with no sign of wear on the first set of bits. The difference is night-and-day better than I was having with the HF bits. :thumbup:

I still have a bit more drilling, some countersinking/reaming and counterboring left to do, but things are looking up. :D Thanks again for the help.

Erin
 
Some times cheapest is not always the cheapest.Good bits go long way.
Stan
 
Soo
Young Grasshopper you learn important lesson ??Cheap drill not so good !!
Why you no call to ask Question Before Becoming Crazy
& try to Play Titanium ??
Just Joking hope it work's out for ya Erin
Have fun
 
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