Lathe question: face grooving toolbit?

[CharlieBravo]

Hi,
I'm building my first titanium silencer and in the quest for low weight I've run into a wall getting the rear end cap as light as possible. As it has the threads for the tube and the threads for the barrel there's a lot of metal between the two threads, I'd like to carve out a groove there in order to save weight.

This is my technical question: Is there a cheaper way to make a face groove in the rear end cap than using a Thinbit DeepGroove setup for +250$?

I'm imagining a carbide toolbit sharpened to be able to carve into the metal (Ti and SS316L in this case).

The dimensions I'm looking for is a depth of about 1/2" and a min diameter of 1-5/64th (1.0781") and 1-9/32th (1.2813"). The width of the groove would be 13/64th (0.2031")
In metric measurements it's a 12mm deep groove with a 5mm width cut in a center diameter of 30mm.

Does anyone know of any tips regarding face grooving that they'd be willing to share?
Thank you!

[Bendersquint]

I tried grinding my own and wasn't worth the effort, so we use commercially available face grooving tool and have never looked back.

Check out Thinbit face grooving tools. Not cheap but last forever and do an awesome job.

[Enfield577]

Hi

I guess it would be tricky to turn, you could try few experiments with HSS on sample pieces (if not in the US then you have even more latitude for experiment)

A couple of other ideas are 1, you could just drill holes, it would not remove as much would be easy, another option if you have access to a mill would be slot drill an rotary table

Cheers

[CharlieBravo]

Thank you Bendersquint and Enfield577. I have huge respect for both of you guys and all your points are valid.
I did try to mill it out using a rotary index table but even with lowly 304SS it flexes too much so I gave up after 3 passes doing 0.050" each pass. It looks like I will have to drill holes in a circular pattern or make up a really good excuse to get the Thinbit setup! The thing about drilling holes is that cleaning those is going to be frustrating and I suppose they will fill up with carbon rather quickly.
Thanks for your input, much appreciated,
Regards,
CharlieBravo

[yondering]

Try the rotary table again on the mill, but use a good 3/16" carbide ball end mill, ~ $20 from Enco, and spin it fast. You might want to use an air stream (if not using flood coolant) to blow chips out of the slot. That should take care of flex issues.

[CharlieBravo]

I'll definitely try that, I'm ordering a carbide ball end mill or two right now, thanks for the tip. Also, I usually flood cool but the pump died last week, I'll rig something up while waiting for the end mill.
If I can get a nice finish that would save me a lot of money and if it doesn't work it's not a big deal. Thank you.

[cal50]

A spade type tool bit works if you do not push it hard. Ball endmills clamped in a tool holder can also work.
Ti is abrasive and generates heat. Don't push hard and take you time and you can carve it out.

[L1A1Rocker]

I recall this coming up in at least one Titanium build. You might try looking through the silencersmith section for completed Titanium builds.

Edit: FOUND IT. Pages one and two cover what I think you're asking about.

viewtopic.php?f=10&t=113750

[CharlieBravo]

L1A1Rocker: Thank you!
I actually saw that post awhile ago while reading up on titanium but promptly forgot about it. I'm trying the two flute endmill trick tomorrow! I've been binge reading the silencersmithing forum, about 100 pages back. It's been very helpful for the can I'm making. I actually saw my first post about it back in June 2.013 so this has to be the slowest silencersmithing ever! I've learnt a lot from here and for me it's been more about the journey than the destination (that's what I keep telling myself at least)

[CharlieBravo]

I tried it today but with limited success. It can be done but you have to mount it just right and modify the end mill so you can really clamp down on it in the toolholder. It vibrated like crazy and I decided it was a bit too messy so I left it alone, there's not a huge weight difference anyway. Might try it again another day. I got about 1/8" down before calling it quits. This was with 316L stainless steel, I didn't want to scrap one of my carbide toolbits but HSS might not be hard enough to make this cut in Ti.

[L1A1Rocker]

HSS might not be hard enough to make this cut in Ti.

Are you using HSS that contains Cobalt?

[CharlieBravo]

Nope, this time I just used a Shars end mill with ti coating, I don't think they have any cobalt at that price point. I wasn't ready to sacrifice a carbide end mill yet. For now I've decided to just leave the end cap without a groove and concentrate on the cones in order to finish the can.

[saigatechusa]

Just remember Drilling is the fastest / easiest / cheapest way to remove material

Drill then mill