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grade 5 drilling question

Posted: Mon Aug 18, 2014 2:20 am
by maccrazy2
Hello all. I finally got around to working on another can. this one is being made from grade 9 TI. I am working on machining a test piece from round stock and had a heck of a time drilling a hole in it. I am working on a 12/36 lathe with flood coolant. Turning is no problem at all. I am cutting it fairly aggressive and am quite happy with the results. drilling however is another story. I verified the tailstock is aligned. I started with HSS center drills. a small one and stepped up to 1/4 then 5/16. they cut fine leaving nice curly shavings. Then tried to drill a small pilot hole and got about .250 in and snapped off the bit. I am trying to keep a constant feed going to keep it cutting and also pulling it to clear chips regularly. I am just having a heck of a time getting a pilot hole drilled. Once I was able to get one I tried stepping up drill sizes. both in small increments and in larger steps. The results were varried. some cut great for a bit then it felt like I am hitting a work hardened spot and it quits cutting and starts to chatter if I try to push thru it. I tried TI coated HSS bits and some cobalt drills. the cobalt were a little better. I also tried a 5/16 carbide drill on a 1/4 hole and same result, I got in about .100 then it chattered like crazy and I chipped the cutting edge.
I know I had a jobber legenth carbide 5/16 drill somewhere in the shop but cant find it. While looking I did locate some 1/4in carbide ball mills. I was ready to give up for the night but wanted to give one of them a try first just to see what would happen. I am glad I did. I center drilled to 1/4. put the ball mill in and let er rip. It drilled a nice straight hole with long curly shavings like i was drilling aluminum. I was applying a moderate amount of pressure in the quill while drilling. I only have 2 test pieces to mess with. I can use the ball mills to get the job done and a mini boaring bar to finish the diameter off but I would like to know where I am going wrong with drilling? Does anyone have any insite for me? Thanks

Re: grade 9 drilling question

Posted: Mon Aug 18, 2014 9:32 am
by Dr.K
Why grade 9 bar? Buy some grade 9 tube, and grade 5 bar. Sounds like you are not being aggressive enough and have work hardened the Ti. Don'tlet aanything dwell in the hole. Ever.

Re: grade 9 drilling question

Posted: Mon Aug 18, 2014 1:54 pm
by maccrazy2
It acts like it is hardening but even with a new clean surface and being very aggressive it just won't drill well at all. Ultimately I can get it done with the endmills. I just fine it odd I can't drill it. I don't plan on wasting any more drill bits at this point.
As for grade of the TI. I found the exact sizes I was looking for all in grade 9 so that is what I will be working with. Is 5 that much easier to work?

Re: grade 9 drilling question

Posted: Mon Aug 18, 2014 2:45 pm
by Dr.K
Not easier, but I'd only use grade 9 for the tube, and not for internals or endcaps. Grade 5 is stronger.

Re: grade 9 drilling question

Posted: Mon Aug 18, 2014 4:46 pm
by Bendersquint
Dr.K wrote:Not easier, but I'd only use grade 9 for the tube, and not for internals or endcaps. Grade 5 is stronger.
Dr. K - Willing to bet that it is Grade5 bar stock, never seen Grade9 barstock in the US....they have some I can import from China but in the US it is pretty darn rare.

If you really did get Grade9 barstock can you send me a link on where you got it?

What speed are you running the spindle at when boring?

We fabricate from Ti daily, both Grade 5 and 9, and don't experience what you are experiencing at all, either on the manual or CNC lathe.

Re: grade 9 drilling question

Posted: Mon Aug 18, 2014 9:48 pm
by wp6529
Bendersquint, can you give us a quick rundown of tips and tricks for machining titanium? My upcoming F1 builds are going to be Ti, both gr.5 bar and gr.9 tube and I have both manual and CNC machines (nothing too big or new).

Re: grade 9 drilling question

Posted: Mon Aug 18, 2014 11:40 pm
by maccrazy2
I will go back and try to find the invoice. I had 9 written on the bar stock but I may have been mistaken.
I have tried from 240 rpm up to 700. Mostly on the 240-400 range. So far I can turn it with std carbide or indexable carbide tools just fine. The ball endmill works great. I also have an indexable chamfering bit that will cut a 60 deg chamfer from the 1/4 hole out to 3/4. It shoots ribbons about 1/2 wide like it is aluminum. Although I can hear the machine lugging a little more. Only did that one time just to see if I could.
HSS TI coated endmills punch thru it ok but I did Loose the corners of the teeth on my 3rd attempt. I was pushing the tool hard to keep cutting and I could see the shavings change shape and I backed it out right away. The shavings stay silver color and I can handle the bit immediately after cutting thanks to the coolant.
I am just at a loss as to the issue. I have one piece left to play with and would really like to figure out what I am doing wrong. I was going to set the lathe as slow as I can gear it and give it one more try with some new guhering (spelling) parabolic drills when they arrive. I have found them to be some of my favorite drills in the shop but did not have any smaller than 5/16.

Re: grade 9 drilling question

Posted: Tue Aug 19, 2014 1:22 am
by maccrazy2
Bendersquint wrote:
Dr.K wrote:Not easier, but I'd only use grade 9 for the tube, and not for internals or endcaps. Grade 5 is stronger.
Dr. K - Willing to bet that it is Grade5 bar stock, never seen Grade9 barstock in the US....they have some I can import from China but in the US it is pretty darn rare.

If you really did get Grade9 barstock can you send me a link on where you got it?

What speed are you running the spindle at when boring?

We fabricate from Ti daily, both Grade 5 and 9, and don't experience what you are experiencing at all, either on the manual or CNC lathe.
You are indeed correct. The tube is grade 9 and the barstock is grade 5.

Re: grade 9 drilling question

Posted: Tue Aug 19, 2014 4:17 pm
by Dr.K
Good sharp cobalt steel drill bit, flood coolant, slow speed. You should punch right into grade 5 with no issues. You have to push though, you can't take teeny tiny skim cuts, titanium hardens quickly, and you have to push through the hardened layer with each turn of the material.

My guess is that if you have the right equipment, and the machine is sound. It has to be your technique. Keep the pressure on it, and withdraw quickly when clearing chips! Dwelling is bad!

Re: grade 9 drilling question

Posted: Tue Aug 19, 2014 5:52 pm
by CMV
I have tried from 240 rpm up to 700. Mostly on the 240-400 range.
That's way too fast for drilling. At least I haven't been able to drill it that fast. Use a new or just resharpened drill & try 60-90 rpm & see if that doesn't work out better for you.

I'm not an expert at it. It doesn't work like PlayDough for me as it does Matt :) Drilling to about 1" - 1 1/8" deep is fine. Any more than that & I'm just as likely to get the SCREECH-Snap as I am to successfully complete the drilling op. Kind of like your experience - I can turn it, part it, thread it, mill it, face it, whatever - but when it comes to drilling it gets very challenging. Anyway, I get the best results pecking after about 1/2" deep. I pretty much keep the handle on the tailstock continuously spinning & the pecks get shorter & shorter the deeper I go as the flutes have a harder time evacuating chips or letting coolant in. But I'm not gentle with the drill. I don't just ram it into the stock - I engage it cautiously, but as soon as it's engaged with the stock, I run it in 'with authority'. Can't describe it better - sorry.

Matt - you'd be my hero if you did up a youtube video of drilling Ti on a manual lathe - maybe about 4" deep or so. Would be very helpful to see it done to get a good idea how a very experienced person sets up & completes the op.

Re: grade 9 drilling question

Posted: Tue Aug 19, 2014 7:47 pm
by john.t.little1
Haven't had a problem yet cutting/drilling G5 drilling I keep it at 115rpm and it cuts flawlessly reaming I go down to 70. Also I've stepped up from 1/2 to 13/16 bits Ti didn't like it but I had coolant going and leaned into the tailstock. Still cut fine tho. Just slow your rpms down under 150 is what works best for me when drilling Ti just let us know what rpms your lathe turns. I've even ran a #7 center boring countersink straight thru 1.5" of Ti before I had larger drill bits. Sometimes you gotta make do lol when turning it I keep it at 755 just so happenes it's a throw of the high low lever to get me from 115-755..

Re: grade 9 drilling question

Posted: Tue Aug 19, 2014 8:41 pm
by maccrazy2
Thanks guys. I will try to set the lathe on it's slowest speed and see what happens. I just ordered some extra rod last night so I have a few more try's to get my technique down before I get going on the baffles.
I also ordered a small diameter boring bar to hopefully be able to cut an internal taper on the back side of the baffles. It will be inside a 1.5 deep bored hole. I was looking for one with a 1/2 shank that necked down to a small cutter with a minimal reduced shank area but could not find much so I bought the closest I could locate. If it won't work I will just build a holder myself.

Re: grade 9 drilling question

Posted: Tue Aug 19, 2014 9:49 pm
by john.t.little1
maccrazy2 wrote:Thanks guys. I will try to set the lathe on it's slowest speed and see what happens. I just ordered some extra rod last night so I have a few more try's to get my technique down before I get going on the baffles.
I also ordered a small diameter boring bar to hopefully be able to cut an internal taper on the back side of the baffles. It will be inside a 1.5 deep bored hole. I was looking for one with a 1/2 shank that necked down to a small cutter with a minimal reduced shank area but could not find much so I bought the closest I could locate. If it won't work I will just build a holder myself.
Slowest isn't always the best either. Like I said I've had good luck in the 115-190 range when drilling Ti best at 115 I don't know what speeds you have tho. Also I'm guessing you are doing baffles with built in spacer? I grabbed a set of boring bars off eBay three pack was micro 100's .25 dia with .25 dia min bore the longest one was close to 1.5" if I remember correct and it flexed a lot. I used the .75 one and made spacers seperately easier and I made them to where they clip together sorta like Tetris so I don't think anything structurally was sacrificed.

Re: grade 9 drilling question

Posted: Tue Aug 19, 2014 9:55 pm
by john.t.little1
http://www.basstool.com/files/mobile/index.html#649


Order almost everything from these guys now. The .320 min bore will be good for what you're doing unless it's 556 but you can adjust.

Re: grade 9 drilling question

Posted: Wed Aug 20, 2014 12:56 am
by maccrazy2
Thanks for the link. they have a large selection of tooling.

Re: grade 9 drilling question

Posted: Wed Aug 20, 2014 10:34 am
by BinaryAndy
I don't think your speeds are really too far out of line for a 1/4" drill. I wouldn't go much faster than 400, and you can always try it slower if it works. How often are you pecking? With Ti and flood coolant you want to retract as rarely as you can get away with. I wouldn't peck at all with a parabolic drill. Use as short a drill as you can.

If the ball mills are working then I'd say keep that up. No corners to destroy, and they should tend to wander less than a drill.

Re: grade 9 drilling question

Posted: Wed Aug 20, 2014 11:42 am
by BinaryAndy
As far as general machining of titanium goes, I find it machines more or less like angry stainless. It work hardens similarly, sticks to tools a bit more, and it's not very stiff so rigidity is harder to come by.

Turning, I treat Ti, 304 and 316 pretty much the same, none of them give me any trouble with sharp tools. I haven't milled much Ti, but I'd keep the RPM slightly lower than I would for ss and pay more attention to rigidity. Drilling is also at slower speeds and similar chiploads compared to ss; use split point drills, sharpen or change them before they get dull, and do as little dwelling and pecking as you can. Use lots of coolant, and watch temps in deep holes (hot titanium will stick to your drill and, in extreme cases, catch fire).

Re: grade 9 drilling question

Posted: Sun Aug 24, 2014 7:50 pm
by mx201er
I burned up several drill bits before I figured it out when I was making my last can.. Look up what sfm and feed speed you should be using for that grade of Ti, should be easy to find on google, and then run the calculations to figure out rpm for a particular sized drill bit. I made an excel file to do the calculations, but this worked great for drilling and even milling with standard mill bits. For my bigger holes, 29/64, I bought a carbide drill bit.

as mentioned above, the drill bits do not enjoy peck drilling

Re: grade 9 drilling question

Posted: Thu Aug 28, 2014 12:52 am
by maccrazy2
It is odd, I can use plain old HSS centerdrills and they cut just fine. I use short jobber drills, standard drills, of several brands and types and just have not been able to get a good cut. I had the best luck with guhhering parabolic drills but I chip the corners on the first hole, even with the chip it punched thru.
I can get it done with the ball mills so that is what I am using. It just bugs me that I am having such issues and dont know why it is giving me so much trouble.

Re: grade 5 drilling question

Posted: Thu Sep 04, 2014 11:05 pm
by maccrazy2
Well I decided to give it another go as I needed a deep hole in my end cap. I was successful in punching thru it using a new guherring parabolic 5/16 drill. Lathe at 240rpm. I hit it with a center drill and then eased the drill bit just until it made contact and layed on the tailstock handle hard. It drilled right thru and the shavings were 2 nearly straight sticks that looked a little rough. Unlike the curly shavings I get from the center drills. Still does not seem right but at this point it will do. It has a nice thru hole and it only took a few seconds to get it.
I have all the bafflels machined to .005 oversize. Tube is cut and faced. I will rough out the mount tomorrow. I need to make a thread plug gauge before I can finish it. Then it will just be the end cap and welding. I am hoping to be shooting it a week from now if all goes well.

Re: grade 5 drilling question

Posted: Fri Sep 05, 2014 12:29 pm
by L1A1Rocker
maccrazy2 wrote:Well I decided to give it another go as I needed a deep hole in my end cap. I was successful in punching thru it using a new guherring parabolic 5/16 drill. Lathe at 240rpm. I hit it with a center drill and then eased the drill bit just until it made contact and layed on the tailstock handle hard. It drilled right thru and the shavings were 2 nearly straight sticks that looked a little rough. Unlike the curly shavings I get from the center drills. Still does not seem right but at this point it will do. It has a nice thru hole and it only took a few seconds to get it.
I have all the bafflels machined to .005 oversize. Tube is cut and faced. I will rough out the mount tomorrow. I need to make a thread plug gauge before I can finish it. Then it will just be the end cap and welding. I am hoping to be shooting it a week from now if all goes well.
Great news! Thanks for keeping us updated. May I assume that you are taking lots of pics of your build to post?

Re: grade 9 drilling question

Posted: Fri Sep 05, 2014 1:33 pm
by Kuraki
maccrazy2 wrote:It is odd, I can use plain old HSS centerdrills and they cut just fine. I use short jobber drills, standard drills, of several brands and types and just have not been able to get a good cut. I had the best luck with guhhering parabolic drills but I chip the corners on the first hole, even with the chip it punched thru.
I can get it done with the ball mills so that is what I am using. It just bugs me that I am having such issues and dont know why it is giving me so much trouble.
Are they 118 degree or 135 degree included angle? Also, step drilling can be very counter productive if your prehole is larger than the web of the drill.

Re: grade 5 drilling question

Posted: Fri Sep 05, 2014 3:08 pm
by calinb
After discovering that I can easily face and turn grade 5 (I like the Arthur R. Warner T15 tooling), I have turned my attention to drilling grade 5, in order to enable boring. I have not yet drilled even a single chip, but I have spent many hours searching and reading several online forums and reading tool maker and Ti vendor spec sheets. Just from memory, here's what I can recall of advice that seemed credible.

1. Carbide drill bits work well but are easy to chip.

2. TiN coated bits are generally not recommended. I don't recall any conclusions about TiAlN or AlTin or TiCN.

3. Use high feed rates.

4. Coolant pressure-fed drill bits, specified to work for Ti by the manufacturer, work the best and eliminate the need to peck. The Guhrrng RT100 VA, available from MSC for under $100, looked good to me and I could probably rig a low pressure coolant feed to it but, without high pressure, I suspect pecking would still be necessary to keep the coolant flowing so I doubt I'll invest.

5. Many sucesses with cobalt bits (M42 preferred) and even ordinary HSS are reported. Here are a few associated tips.
  • Grind the flutes slightly (from behind the drill bit corners back) to reduce their diameter and the rubbing and binding of the flutes on the bore walls, which results in heat.

    SFM should be VERY low. I found Ti vendor datasheets that recommended speeds as low as 15 SFM and user recommendations as low as 20-40 SFM.

    Ti doesn't like being drilled undersize first. You can spot the hole or drill a very small pilot, but then drill to final size.

    Lacking coolant pressure feed, drilling on a milling machine can work better than horizontal drilling from the lathe tailstock. Vertical drilling enables longer pecks, because gravity tends to keep the coolant in place. A milling machine or drill press also provides a better "feel" to the hand of a manual machine operator.

    135 or 140 degree parabolic drill bits seem to be preferred, but more common lower helix angles work too.
6. Tapping Ti is even more challenging!

Given all of the above, I plan to spot with a 140 degree carbide spotter and try both carbide and M42 135 degree drill bits. At least I can sharpen them myself as often as necessary. Given what maccrazy2 reports here, I'll fall back to the ball nose end mill, if necessary, but I don't know how to sharpen one of those!

Again, I have no actual experience in the art and science of drilling titanium.

Re: grade 5 drilling question

Posted: Fri Sep 05, 2014 3:44 pm
by john.t.little1
I had no Issue but again was slow 115rpm and flood coolant and the inserts I used were uncoated.

Re: grade 5 drilling question

Posted: Fri Sep 05, 2014 4:17 pm
by wp6529
4. Coolant pressure-fed drill bits, specified to work with Ti by the manufacturer, work the best and eliminate the need to peck. The Guhrrng RT100 VA, available from MSC for under $100, looked good to me and I could probably rig a low pressure coolant feed to it but, without high pressure, I suspect pecking would still be necessary to keep the coolant flowing so I doubt I'll invest.
I keep thinking that a cheap $99 Harbor Freight electric pressure washer would make a useable pump for coolant fed tooling...