Punkinhead's build plan

[punkinhead]

I decided to do this with a form tool in the lathe instead of a ball end mill so I didn't have to set up the rotary table:







This doesn't look fun to deburr:



After some work with a small round file. It still needs a bit more attention:

[whiterussian1974]

Could you click a pic turning the K about 60* counter-clockwise and with the mousehole at the top?
I'd like to get a glansing view of the face and look through the mousehole w nothing but your plans behind it. That way I can have a better view of the unobstructed geometries.

[punkinhead]

Could you click a pic turning the K about 60* counter-clockwise and with the mousehole at the top?
I'd like to get a glansing view of the face and look through the mousehole w nothing but your plans behind it. That way I can have a better view of the unobstructed geometries.

Is this what you mean?



I finished turning all the baffles but haven't done the mouse holes yet on any but the first, so there's time for change if there's something wrong with how I did the holes.

I'm also thinking ahead to the end caps. Can they both be aluminum or should the one nearest the gun be stainless? It seems like the end caps are inherently capable of taking the pressure so stainless might be overkill. They're not going to collapse like a k-baffle. I did make what will be the first k-baffle out of 304 stainless. Not near as much fun (or fast) to turn as 6061.
EDIT: Thread galling might be a problem between aluminum and stainless. Anodizing and assemly with anti-seize would reduce it though.

[ChimeraPrecision]

make the mount out of stainless. years of happy mounting and dismounting will ensue

[punkinhead]

Another question: location & size of dater hole on the first baffle. I'm thinking aroud .100" diameter. What about location relative to the mouse hole? I've seen pictures of the dater lined up with the mouse hole and at 90 degrees to it.

[MCKNBRD]

Another question: location & size of dater hole on the first baffle. I'm thinking aroud .100" diameter. What about location relative to the mouse hole? I've seen pictures of the dater lined up with the mouse hole and at 90 degrees to it.

Therein lies the question! I've seen them 90*, 180*, inline with, and right beside the scoop on the face. I have no idea which is better, or if it makes a huge amount of difference.

I do remember that the size needs to be tailored to your can...so I'd say start with a smaller than expected drill, then shoot it, then step up until you like the sound. IIRC, .125" is about the max for a .22, but I'm not sure.

Byrdman

[punkinhead]

I threaded the tube and made the end caps yesterday. I plan to trim the rear end cap to get the right clearance so the baffles aren't under compression. Any idea what I should shoot for as a clearance? I don't want the baffles under compression but I don't want them to rattle either. I'm also wondering if I need to account for thermal expansion since aluminum has about a 30% higher coefficient of thermal expansion than stainless steel.

I chased my tail for quite awhile trying to get the tube dialed in on the 4-jaw chuck. I finally realized I was deforming the tubing with the jaws even with light to moderate pressure. I ended up making a collet by boring a hole in a piece of Delrin (aluminum would have worked) and splitting it on the band saw. This seemed to even out the forces and I was able to get the runout down to under .001".

[Baffled]

^^ Nice technique. If you can scrape the $$ together, look for an "adjust-tru" style of 3 or 6 jaw chuck to fit your spindle. You'll never use your 4-jaw again.

The 6-jaw is especially desirable because the jaws are very fine and spread the pressure evenly; a 6-jaw adjust-tru chuck can be considered to be a set of collets with infinite division. A good 6-jaw can grip the thinnest tube without distortion.



Your build is looking good!

[punkinhead]

If you can scrape the $$ together, look for an "adjust-tru" style of 3 or 6 jaw chuck to fit your spindle. You'll never use your 4-jaw again.

You got me curious so I went out and looked. $1000 is the price of entry - guess I'll have to save my pennies.

Ready for engraving and Cerakote. The aluminum baffles are in the anodizing bucket at the moment.





This is addictive. Time to e-file for a couple more stamps...

[Dr.K]

Looking good Pumpkinhead! Now knowing what it takes to do one of these projects, I appreciate the work like this so much more now than I did before. At one point in my life, I thought you could just whip out a can in a couple of hours on a lathe.

Range report?

[Baffled]

If you can scrape the $$ together, look for an "adjust-tru" style of 3 or 6 jaw chuck to fit your spindle. You'll never use your 4-jaw again.

You got me curious so I went out and looked. $1000 is the price of entry - guess I'll have to save my pennies..

I'm not sure where you looked... here's a 6" for $495 new.

http://www.ebay.com/itm/6-GATOR-Lathe-C ... 3a8b7a235a

The thing about these - since they adjust, you don't need the screaming precision that is ground into the scrolls of high-end plain-back chucks.

Still not cheap, but it's my #1 favorite and most-used piece of lathe tooling.

It's strange, the last time I priced chucks seriously was maybe 10 years ago. Bison, made in Poland, was an unbelievable bargain. The Poles make some truly nice tooling. IIRC a Bison 6" 6-jaw was $329 or thereabouts. Now, the same chuck is $800. It looks like foreign exchange with the Zloty or whatever it is, has finally caught up.

[Shift1]

very nice work...any range reports?

[whiterussian1974]

Yes, sweet build. Even a subjective report from multiple observers/positions would be good if you don't have a cam.
Sometimes subjective reports can even be better, since cams have limited mics.

[punkinhead]

very nice work...any range reports?

I've had to work in Mexico the past couple weeks but got lucky and got it back from engraving a couple days before I left so my son and I took it to the range. It's my first suppressor so I really have nothing to compare it to. We shot it first through the SR22 with subsonic ammo. My subjective opinion would put it at about the sound of a springer air rifle. Loud enough that the neighbors would hear it but definately no need for hearing protection. We then shot it with a Ruger 10/22. That gave the 'pffft' about as loud as a bolt action air rifle (practically nothing), the sound of the action working, and the thump of the bullet hitting the paper. Very cool. If the weather cooperates tomorrow I'll get some video. I have 2 bolt action .22LR rifles but they're both keepsakes I've had since childhood so I don't want to thread them. I'm going to keep my eye out for a used one for threading.

I also had the guy who engraved it do the Cerakote. It was a no brainer. Cerakote-C would have been $35+shipping for 4oz. He charged me $40 to coat it and did a much nicer job than I could have. I suck at any kind of painting.

[John K]

I threaded the tube and made the end caps yesterday. I plan to trim the rear end cap to get the right clearance so the baffles aren't under compression. Any idea what I should shoot for as a clearance? I don't want the baffles under compression but I don't want them to rattle either. I'm also wondering if I need to account for thermal expansion since aluminum has about a 30% higher coefficient of thermal expansion than stainless steel.

I chased my tail for quite awhile trying to get the tube dialed in on the 4-jaw chuck. I finally realized I was deforming the tubing with the jaws even with light to moderate pressure. I ended up making a collet by boring a hole in a piece of Delrin (aluminum would have worked) and splitting it on the band saw. This seemed to even out the forces and I was able to get the runout down to under .001".

Another thing you can try to help beef up rigidity is to select a piece of barstock that's a slip-fit for your tube.

I went with a shouldered rear cap, and a front cap with a major OD the same as the threads. I make the tube ~0.100" "long", and then trim the tube after installing the stack and caps. This way I can also add wipes to my can, without having a gap between the front cap and the tube. You can also adjust the preload to your liking.

I guess I should do a write-up.... I've got some testing to do Wed on baffles V4.0 and V4.5, if they work without collapsing, I'll post some lessons learned.