Titanium Silencer on a Form 1

[L1A1Rocker]

Aren't you glad this is just a hobby? You'll be proud of that when you're done. Me, I'm just going to buy stuff produced by professionals and modify it as necessary. When an 11" finished tube with threaded ends is only $90 and I have no lathe or Ti-specific tooling it's either that or buy a commercial silencer.

Hopefully it'll be something to be proud of when done. You know there is another option. You could buy a lathe.

At least you are doing your research ahead of doing your project. This poor fellow is not happy with his form 1 at all: http://www.silencertalk.com/forum/viewtopic.php?f=10&t=135439

I've read about some builds like you are planning. There's been some really happy campers going that rout.

 

[Pistolero]

Wow, he says no noticeable reduction! You'd think that you'd get SOMETHING with his set of baffles.
Never studied the topic significantly, so no real tech knowledge.

Bill

 

[L1A1Rocker]

Well, after making the muzzle support I removed the big peace of titanium, cleaned the lathe, and got ready for the next step. It was time to carve out the inside of the cone baffles.

And here we go.



The first part was to bore out the "skirt" portion to a wall thickness of .06.



After drilling for a bit I switched to a boring bar.



Getting bigger



And there



The next part was/is to bore out the inside of the cone portion. BUT! I've run into a bit of a problem. Here's where I left off tonight.



Now I've got a lot more to go, and with each pass the wall of the cone gets a bit thinner. But when do I stop? I want the wall between .065 and .07, but I really cannot figure out how to measure it because it is sitting inside the jaws of the chuck leaving me very limited access. Anyone have any suggestions?

 

[Pistolero]

Why not just measure with calipers between the jaws?

Looks really nice.

Bill

 

[L1A1Rocker]

Why not just measure with calipers between the jaws?

Looks really nice.

Bill

Because the measurement will be from the top of the skirt to the bottom of some random point along the inside of the cone. I need to get over and around the top of the skirt somehow so that I'm measuring each side of the cone.

I could just take the cone out of the jaws and measure it. Then put it back in, and re-index the cone and take a cut, and repeat. . . But that's really "bad form", as they say. I was hoping for an easier approach.

Oh, and thanks.

 

[smokeywolf]

Do you have a way of knowing within a few thousandths your carriage travel? Trav-A-Dial, carriage stop, dial travel indicator?

Think I'd dial my cross-slide out so that my boring bar is outside the O.D. of the part.
Carefully move carriage forward so as to bring the end of the boring bar even with skirt-cone juncture; just eyeball it. Now back off .035".
Mark location of carriage; zero on your dial travel indicator or set a deadstop/carriage stop.
This should give you at least a pretty good idea where to stop advancing your carriage as you take your passes with the compound to establish the inside of your cone.
You may still have to pull the part out once to check dimensions, but this will get you to a point where you can establish where your are and how much further you need to go.

This is also where a chuck which allows for machinable soft jaws can be a saving grace.
Either that or a 6 jaw chuck which allows for good clamping of thin-walled parts while causing minimal distortion.

And this is what machinists call "painting yourself into a corner".
What you're doing is not apprentice level work. I sit down and plan out every operation before clamping the raw stock in the chuck and I still get stuck on occasion.

If you ever do this again, I would do all my internal work first. Then, make an expanding mandrel to fit the bore. Hold on to the I.D. of your workpiece with the mandrel and finish the outside of the cone last. Doing it this way allows for pulling the part off the mandrel, checking dimensions, then putting it back on the mandrel and taking additional cuts.

Hope this is of some help.

 

[L1A1Rocker]

Do you have a way of knowing within a few thousandths your carriage travel? Trav-A-Dial, carriage stop, dial travel indicator?

Think I'd dial my cross-slide out so that my boring bar is outside the O.D. of the part.
Carefully move carriage forward so as to bring the end of the boring bar even with skirt-cone juncture; just eyeball it. Now back off .035".
Mark location of carriage; zero on your dial travel indicator or set a deadstop/carriage stop.
This should give you at least a pretty good idea where to stop advancing your carriage as you take your passes with the compound to establish the inside of your cone.
You may still have to pull the part out once to check dimensions, but this will get you to a point where you can establish where your are and how much further you need to go.

Hummm, I did something very similar on another part a few years ago. Don't know why it didn't come to me to do that thanks.

And this is what machinists call "painting yourself into a corner".
What you're doing is not apprentice level work. I sit down and plan out every operation before clamping the raw stock in the chuck and I still get stuck on occasion.

That's why you will NEVER see me claim to be a machinist, or an apprentice, or even a novice. I am a hobbyist, nothing more. What I've learned, I've learned from reading books, watching a few videos on the internet, and asking questions on the internet. This particular "cone project" is from watching a video where the person did his operations this way. I figured there was a measuring tool I was missing in my tool cabinet. I think I mentioned I do a lot of cleaning as it allows me to do a lot of thinking on "how" to do the next operation.

I often will "model" my work in Delrin first, so I have everything lined out beforehand. (as I did with the muzzle brake) Such is not possible with doing silencer baffles as it is not legal. Creating a plastic baffle as a "model" would be considered an illegal silencer part in the eyes of the ATF. Sooo, at some point, without any coach watching over my shoulder, I have to jump in and just do it. If I screw it up, well. . . that's really my final way of learning - through experience.

If you ever do this again, I would do all my internal work first. Then, make an expanding mandrel to fit the bore. Hold on to the I.D. of your workpiece with the mandrel and finish the outside of the cone last. Doing it this way allows for pulling the part off the mandrel, checking dimensions, then putting it back on the mandrel and taking additional cuts.

Hope this is of some help.

I had considered a mandrel. What I was thinking of was to machine out a cone from round stock that would be threaded on the outside. Machine the outside of baffle, fit it inside the mandrel, and then screw a hollowed out "cup" to hold it inside the mandrel. Then I'd be able to remove the part and check it from time to time as needed. I decided to just follow the video I had seen of doing it this way. BUT, that video never mentioned checking final dimensions. Had I been able to model this first, it would have become apparent.

 

[IllinoisCoyoteHunter]

Good advice above. As a beginner, I am learning too. Would a 4 jaw check be advantageous instead of a 3 jaw to get the part back as close as possible if it has to be taken out for measurements? Thanks and sorry if this is considered a thread hi-jack.

 

[smokeywolf]

L1A1Rocker, please don't take my advice as criticism. It is not meant that way. My suggestions are merely what I would do from what I know of your tooling, lathe and the parts you are trying to turn out.
I've seen people finish an apprenticeship with less knack, talent, know-how than you obviously possess.

The mandrel I had in mind would resemble one of these...
forgive the dirt, they've been sitting in a cardboard box on the floor for the last 13 years.
Another set of expanding mandrels in a wood block...

Start with...

• Round stock; little larger dia than O.D. of part, steel or aluminum, turned to within 20 to 30 thousandths over finish dia. (inside dia. of skirt area) of cone.
• Drill and tap mandrel nose for allen cap screw. Allen wrench must be able to fit through hole in cone; that is what determines size of allen cap screw used in end of mandrel.
• Countersink end of mandrel using 60 degree center-drill, center-reamer or countersink.
• With band saw, slitting saw or hack saw, cut 4 or 6 slits in mandrel as seen in pics.
• Deburr mandrel threads where slots were cut through. I usually fold a piece of wet-or-dry or emory and slide it through the slots, then run the tap back in and out.
  
• In chuck or collet, (if chuck, pad the jaws) using compound, turn taper on allen cap screw to match C-sink in nose of mandrel.
• Mount mandrel in chuck. (With Sharpie, I sometimes put a witness mark and jaw number on the mandrel so I can remove mandrel from chuck and still have a chance of putting it back at a later date fairly close). Make sure mandrel is far enough out from chuck jaws so that jaws won't interfere with machining of workpiece.
• Screw your 60* allen flat head into mandrel.
• Tighten allen screw just snug enough so that it won't back out during finish cut(s) on O.D. of mandrel.
• When turning O.D. of mandrel to finish dia. make sure surface finish is as good as you can get. This reduces chances of part spinning on mandrel during turning/facing operations.

Ideally, you don't want to remove the mandrel from the chuck until all profiling operations have been finished.

ICH, depends on the size, jaw configuration and quality of the chucks you're working with.

 

[Ian]

Since my lathe experience consists of having been close enough to at least three of them to notice that they exist as I walked by, I have no idea of the particular challenges involved when actually putting bit to metal. This is an interesting puzzle though, and I bet that with a good pair of Swiss 6" calipers, three hands, and 1" micrometer standard I think I could get pretty close to measuring the thickness of the angled part. It would be best to have a standard with a point on one end. Some math could be done on the chord length of the inside diameter where you put the standard, since a flat-ended standard wouldn't touch but on the edges. I have to measure weird shapes at awkward angles frequently at work, so one has to get creative. The fixed jaw of the calipers would be placed between two of the chuck jaws and flat against the outside of the cone. The moveable jaw would be brought up against the standard and applied to the inside of the cone, and the necessary subtractions done from the measurement.

Are all the baffles going to be cones with integral spacers? If so, when you get out of the weeds on this one, wouldn't T-Rex's method be easier for you on the remaining cones? It seems like it would solve jaw pressure distortion issues as well as simplify the measuring of the cone thickness.

I understand that your tailstock won't allow the full length of the remaining workpiece to be put in the chuck like the drawing, but I was thinking maybe that little three-screw support thingy you have with the rollers added might work and you could still accomplish the same thing. Is there a vibration issue with that vs. working close to the actual chuck?

 

[Brad]

Seems to me that either of those ideas could work.

Smokey, the expanding mandrel is a neat idea. Reusable and adjustable. I like that.

Would it be possible to make a flat gauge the proper size and shape to use to judge the cutting depth?

 

[IllinoisCoyoteHunter]

Would it be best to try and leave the mandrel chucked up and use a hacksaw to cut the slits?

I am glad I came over and joined this site. Lots of good info here. I appreciate the time the members put into their responses. Really helps beginners like me! I think I can see a subforum coming... Lathey Days

 

[Ian]

Quality of all things, not quantity, has been the focus of this site from the beginning. You just described why.

As you might imagine, there's been a heated informal competition to see which one of us can convince Smokeywolf to be their neighbor when he decides to move back to America.

 

[Brad]

I think Rick is in the lead.

I would be satisfied with visiting him for a week in the shop. My head might just explode.

 

[smokeywolf]

Ian that could work. Particularly if concentricity must be maintained within .001.
However, as you also pointed out, rigidity could prove to be insufficient to produce satisfactory tolerances and finishes.
Also, if you are producing more than 2 or 3 parts, because of rigidity problems requiring very light cuts, the task could get quite tedious.
Keep in mind, titanium is tough, but in comparison to many metals it's butter soft.
Lack of rigidity of a workpiece on a lathe makes the workpiece tend to push away from the toolbit. Then, all of a sudden the toolbit digs in and causes the workpiece to try and climb the toolbit. Then there's the problem of chatter, which is the afore-mentioned pushing away and climbing action of the workpiece at a frequency that produces a sort of soft or muted knurled look or orange peel pattern.

The method you suggest is usually the first one a machinist looks at and if fabricating ones-ies and twos-ies of something is the preferred method. One of the first things taught is to try and design a setup where as many operations as possible can be done "in one chucking".


Brad, not sure what you mean by "flat gauge".

 

[Brad]

Think of the baffle as a 2D drawing. Take the inside dimensions and transfer them to a poece of sheet metal. Cut it out and use it to gauge the depth of cut and shape. Using the open end of the baffle as a stop point it wouldn't be too hard to judge progress.

 

[smokeywolf]

ICH, if you feel that that is the easiest positions for you to saw semi-straight and semetrical slots, then sure, you could leave the mandrel in the chuck.

 

[smokeywolf]

Think of the baffle as a 2D drawing. Take the inside dimensions and transfer them to a poece of sheet metal. Cut it out and use it to gauge the depth of cut and shape. Using the open end of the baffle as a stop point it wouldn't be too hard to judge progress.

Ah, like the flat radius gauges. Now I got it.

I think, as long as I'm machining an expanding mandrel, I'd machine part of the nose of the mandrel to match the taper of the inside (and outside) of the cone. One at a time, rough outside profile on all my pieces. Then, come back and just barely touch my toolbit to the tapered nose of the mandrel, dial the carriage out the .070" that L1A1Rocker specified for thickness, lock down the carriage and with the compound, do the finish pass(es) on the outside taper.

 

[Brad]

Now you know why I say the hardest part of machine work is understanding how to make the part. The thought process is the hard part to learn, the actual work is just repetition.

 

[smokeywolf]

This is the easy stuff. Setups on the mill really get challenging.

Took 20 years before I felt right about calling myself a "machinist". I think about all those machinists back in the 1800s at Winchester who produced parts as good or dog-gone near as good as mine, and did it with the technology available at that time.
In the parlance of my trade, I'm a "class 'A' machinist"; that's the highest rating. Those who produced gun parts for Colt, Winchester, Remington and many others, back when industry was powered by water and steam, they were "master machinists".