Questions about drilling titanium and SS

Yes, it can be legal to make a silencer. For everything Form-1, from silencer designs that are easily made, to filing forms with the BATF, to 3D modeling. Remember, you must have an approved BATF Form-1 to make a silencer. All NFA laws apply.

Moderators: mpallett, bakerjw

Post Reply
Mordeuis
New Member
Posts: 2
Joined: Sun Mar 29, 2020 10:24 pm

Questions about drilling titanium and SS

Post by Mordeuis » Sun Mar 29, 2020 10:29 pm

Hey all,

First time posting. Posted this over on r/form1 but I suspect The audience here is much larger. I’ve been doing a ton of research here and on other forums in my pursuit of building my first form 1 suppressor. I’ve been reading about RPMs, SFMs, feed rates, etc. and it’s reminding me why I didn’t do well in high-school math. Despite my research, I’m seeing consistently contradictory advice about what tools to use, what kind of drill bits to use, how fast to cut, etc. I’m hoping some of you more experienced builders can give me some advice.

To break it down in detail, I am planning to build from a MMW kit. I am particularly concerned with drilling the gr5 titanium, 0.065” thickness end-cap. I’m mildly concerned with drilling the SS cups, but I figure if I can drill the end cap without issue I can probably drill the cups - please feel free to school me on this.

If money were no object, I’d be using the ideal tools - a lathe and the best carbide bits I could find. Unfortunately, money is a major constraint, and as such, I have at my disposal a HF floor drill press with a minimum speed of 220rpm.

I’m willing to spend a decent amount on my bits, but I’m reading that HSS or cobalt is sufficient, and that I shouldn’t spend the money on carbide. I’m planning to use a 3/8” bit so that I can use the suppressor for both my 5.56 and 300BLK uppers.

Right now, my thinking is that I need to drop my press down to the lowest speed, get some mechanics length or screw machine length cobalt bits (from grainger), use a ton of cutting fluid, and take about 1/16” per pass, giving the bit plenty of time to cool between each cut.

I know that centering will be an issue with a drill press - this is a risk I’m going to have to take in the absence of a lathe. I’m planning to rely on the dimples, my drill press vice, and my digital caliper to get the holes as concentric as possible.

So, considering all of the above, what pitfalls should I be aware of? Thanks in advance for any and all help.

#40Fan
Silent But Deadly
Posts: 206
Joined: Tue Nov 20, 2018 6:41 pm

Re: Questions about drilling titanium and SS

Post by #40Fan » Mon Mar 30, 2020 12:45 am

I have used cheap drill bits from HF that were coated and rather expensive cobalt bits. Both did the job if care is taken. I always recommend the cobalt because they will take a little more abuse.

MMW's endcap doesn't have dimples/centering marks.

Gibs
New Member
Posts: 6
Joined: Tue Feb 11, 2020 4:21 pm

Re: Questions about drilling titanium and SS

Post by Gibs » Mon Mar 30, 2020 6:16 am

You can accomplish good results with a drill press AND keep your holes centered by getting the alignment jib made by number40fan over on the form1suppressor.boards.net site. He can also supply it with the appropriate drill and he's making them for pretty much every size baffle from every mfg. Once done you can check your alignment by getting some of McMaster-Carr's Tight-Tolerance Oil-hardening 01 Tool Steel Rods for the appropriate caliber to check your bore. I got one for my .223/5.56 as well as for .30 cal. I paid around $6.00ea plus shipping and had it from them the next day after placing the order at 3pm.

User avatar
T-Rex
Silent But Deadly
Posts: 1864
Joined: Wed Oct 29, 2014 4:38 pm
Location: CT - The AntiConstitution State

Re: Questions about drilling titanium and SS

Post by T-Rex » Mon Mar 30, 2020 8:57 am

HSS is absolutely fine, for both SS and Ti, @ 220rpm. You don't need "tons" of cutting fluid. HSS can cut both materials dry and you're not going to make a ton of heat as the front of those cups aren't thick. A singl drop of oil, just to get started, is all that's needed.

What do you mean "1/16 per pass"? I thought you were drilling. Are you going to try and mill w/ that drill press? I wouldn't go for it.

As for speeds and feeds here
Completed Builds www.silencertalk.com/forum/viewtopic.php?t=79895
Burst Calculator www.engineersedge.com/calculators/pipe_bust_calc.htm
Silencer Porn www.instagram.com/explore/tags/silencerporn/

Mordeuis
New Member
Posts: 2
Joined: Sun Mar 29, 2020 10:24 pm

Re: Questions about drilling titanium and SS

Post by Mordeuis » Mon Mar 30, 2020 10:36 am

Thanks to everyone for the responses - all extremely helpful!

T-Rex - reading it now, I see how what I said sounds like milling. To clarify, I meant taking shallow cuts until the drill breaks through. Of course, with the end cap being so thin, I would break through in a single press. But, just as a general rule, do you suggest trying to take a little at a time, or using heat as a guide for how deep to cut at any one time?

User avatar
T-Rex
Silent But Deadly
Posts: 1864
Joined: Wed Oct 29, 2014 4:38 pm
Location: CT - The AntiConstitution State

Re: Questions about drilling titanium and SS

Post by T-Rex » Mon Mar 30, 2020 11:07 am

Let's assume you're drilling properly. Starting w/ a center drill, the hole should already be broken thru, on a thin part. Following with the final drill size shouldn't take too much effort. Pecking is a good practice. Let the metal, the machine, and the cutting bit tell you what should be done. This is the way!
Completed Builds www.silencertalk.com/forum/viewtopic.php?t=79895
Burst Calculator www.engineersedge.com/calculators/pipe_bust_calc.htm
Silencer Porn www.instagram.com/explore/tags/silencerporn/

User avatar
fishman
Silent But Deadly
Posts: 1444
Joined: Sun Dec 20, 2015 9:15 pm

Re: Questions about drilling titanium and SS

Post by fishman » Mon Mar 30, 2020 1:22 pm

Like others have said, any drill bit will work -- even dry. Better bits just last longer and can do work faster. The key is that your bits are sharp. If you dont know how to sharpen them by hand, buy a drill doctor.

Theres no need to cut 1/16" at a time for such a thin part. 200-400 rpm will work well. Use a small amount of cutting fluid and you'll be fine. Let the bit cool between parts.
300 blackout form 1: http://www.silencertalk.com/forum/viewtopic.php?f=10&t=137293

5.56 form 1:
http://www.silencertalk.com/forum/viewtopic.php?f=10&t=141800&p=955647#p955647

User avatar
T-Rex
Silent But Deadly
Posts: 1864
Joined: Wed Oct 29, 2014 4:38 pm
Location: CT - The AntiConstitution State

Re: Questions about drilling titanium and SS

Post by T-Rex » Mon Mar 30, 2020 2:04 pm

fishman wrote:
Mon Mar 30, 2020 1:22 pm
Let the bit cool between parts.
Not that this is bad advice, it isn't conducive to proper machining. Your chips should be taking away the vast majority of heat. So much so that your tool bits shouldn't be getting "hot". You should be able to touch a drill/tool bit, immediately after the cut. If your speeds and feeds were correct, it should only be mildly warm. If you're using any type of coolant, the bit shouldn't get too much above ambient.
Completed Builds www.silencertalk.com/forum/viewtopic.php?t=79895
Burst Calculator www.engineersedge.com/calculators/pipe_bust_calc.htm
Silencer Porn www.instagram.com/explore/tags/silencerporn/

User avatar
YugoRPK
Silent But Deadly
Posts: 6289
Joined: Wed Apr 02, 2008 3:56 am
Location: South Carolina

Re: Questions about drilling titanium and SS

Post by YugoRPK » Thu Apr 02, 2020 2:47 pm

Carbide 2 flute end mills . You buy it once and never regret it.
Putting the laughter in manslaughter

User avatar
fishman
Silent But Deadly
Posts: 1444
Joined: Sun Dec 20, 2015 9:15 pm

Re: Questions about drilling titanium and SS

Post by fishman » Mon Apr 13, 2020 10:44 am

T-Rex wrote:
Mon Mar 30, 2020 2:04 pm
fishman wrote:
Mon Mar 30, 2020 1:22 pm
Let the bit cool between parts.
Not that this is bad advice, it isn't conducive to proper machining. Your chips should be taking away the vast majority of heat. So much so that your tool bits shouldn't be getting "hot". You should be able to touch a drill/tool bit, immediately after the cut. If your speeds and feeds were correct, it should only be mildly warm. If you're using any type of coolant, the bit shouldn't get too much above ambient.
A lot of hobby grade drill presses and lathes cant feed fast enough for this to really work with titanium.
300 blackout form 1: http://www.silencertalk.com/forum/viewtopic.php?f=10&t=137293

5.56 form 1:
http://www.silencertalk.com/forum/viewtopic.php?f=10&t=141800&p=955647#p955647

Post Reply