May 31, 2008 at 5:10 pm #2237
I think I hit pay dirt with my new shroud design! Many of the versions I’ve seen here and other places are over-thought, add more weight and reduce more volume than necessary.
I recently bore scoped a well known makers’ dust collector at work to see exactly what’s inside. No magic, but I think I now know his mojo.
The one I made is actually on a BSA Sportsman HV but the construction would easily adapt to the Talons. My next one will be for my Talon SS.
His had three perforated tubes, wrapped in fiberglass and separated by washers. No expansion chamber. It works extremely well. I rough measured the perforated tubes ( 9/16″ x 1-1/2″) and found something at work that was identical. We use them for 1/2″ steam Y-strainer inserts. I ordered some at work, to replace worn out ones of course, and tried them out. LOL
I think I may have also found them in a McMaster-Carr catalog too (page 340-343). The ones to fit 3/8 and 1/2 strainers. They’re about $7-9 each and made of 304 stainless. I didn’t want THAT much added length so I cut them down to 1″ each, for a total of 4.75″ beyond barrel, including blast baffle, guts and endcap. In hindsight, I shouldn’t have even bothered.
I made some alum. washers on the lathe vs fender washers for a precise .930″ fit.
I wrapped the strainers tightly in strips of fiberglass window screen (6ft each), cut to same width as strainers length. I bought a repair roll from Home Depot to try out (it works). A tip I learned was once they’re hand wrapped, I place them on a table and lay a stiff ruler on top and continue to roll them, under pressure, to reduce their diameter and increase their density. Two 36″ lengths of wrapped screen will reduce down to perfectly fit a 1″ tube snugly. I did up all three and used some tape to hold them together until ready for install.
I made a tapered blast baffle to direct air rearwards back into the shroud instead of a regular flat washer. This got red loctite and a snug press.
I then made up a three sided vent bushing, versus radial holes, and used brass countersunk screws to affix the bushing permanently to the tube. I did this for lack of a rotary table. 😥 I countersunk them just enough to put the countersunk head in shear with the tubing and bushing but still leave the screw slot exposed so it could be turned down. These had red loctite applied prior to assembly.
I then turned down the CS screw heads flush w/ the tubing and threaded the bushing center to screw onto the barrel threads to make my shroud removable. For the Talon, a close fitting hole would work fine. I went the extra distance here so when the shroud is screwed on and off, there’s more than just loctite holding the bushing in place, considering the torque applied. Once the tubing is painted, there are no visible screws either.
Looks are one thing but effectiveness is quite another. It works better than I could have imagined from 1″ tubing. I’m getting the proverbial “Hammer click” from 30+ ft/lbs. I plan to measure the sound with an old RadioShack dB meter. I’ll also test w/ shroud removed and on an empty air tank for pure hammer noise.
First shots started off 2″ low at 25yds. but no clipping was evident.
My 50 yd groups are still dime and nickel sized so I think it will do fine for what I want. The starlings aren’t spooked and are standing around watching their buddies fall over, waiting their turn. LOL Two and threesomes are less rare now.May 31, 2008 at 6:43 pm #39869martin777Participant
Simply BRILLIANT! 💡
Bore scope—Inquiring minds want to know! 😀
3 sided vented bushing–What can I say!
Y-strainer inserts (304 stainless no less) AND
turned down brass countersunk screws–Now that’s class!
I’m building a .25 cal. Condor and my mod. is 1½” dia.
I figure I need that extra volume for an 85fpe+ shot.
I will post pics. of the guts when I’m finished.
Welcome to the forum. You’ll meet a bunch of great guys
here that think alike.
You’ve given us some NEW unique ideas. That’s what this
board all about (most of the time).June 1, 2008 at 6:00 am #39894slipkidParticipant
Can you please post the part number for the strainer?
SlipkidJune 1, 2008 at 11:18 am #39899martin777ParticipantJune 1, 2008 at 3:07 pm #39907quote Slipkid:
The ones I used came from a local supplier we use at work.
McMaster -Carr deosn’t list the insert dimensions but the ones I used were for a 1/2″ Mueller Y-strainer. I think they’re model 590’s.
Different strainer designs may have different insert dimensions. A 3/8″ strainer insert might work also.
I would think you’d only want perforated tubing and not screen mesh. They offer both types. The screen mesh may distort under pressure.
If anyone’s interrested, I could get the phone number for our local distributer and the exact ones I use could be ordered. The company is called McJunkin Inc. in Cincinnato, OH.
PM me if you want.June 1, 2008 at 8:04 pm #39916photo22Participant
haywire1 that’s a nice looking design 😀June 1, 2008 at 8:21 pm #39919walkonkingParticipant
Awesome. Great design and a good project for a diy.June 1, 2008 at 8:50 pm #39921walt-in-hawaiiParticipant
Haywire, in your picture of the naked perf tubes, how long are those tubes? In your narrative you said you cut them to 1″, but eyeballing those pieces in your photo they look to be closer to 1 1/2″ or so.
waltJune 1, 2008 at 9:31 pm #39922
Thanks guys, for the kind words. Simple designs are wonderful. I had the design in my head for a while and just had to wait for work to slow down so I could play in the shop.
You guys would freak out if I posted pics of the jig I made to actually mill the bushings. It involves a 1/2-13x 4″ long bolt thats been pressed into a drilled out piece of hex stock. The hex stock is used in the mill vise to index the three sided shape from round stock. Turn down the round stock first to light press fit tubing ID. It’s too hard to mic the dimension once it’s three sided.
I tapped the bushing hole first. Then thread this onto the hex stud and lock it down with a jam nut made from a turned down regular nut. It has to be turned down to give cutter clearance for the three sides. I knurled it to give some teeth since I took off the flats. I use channel locks to remove it. It also requires a sacrificial spacer to shim the bushing up off the hex stock. I used a flattened lock washer. It gets milled on so plan to make a couple extra. I used a new one with each bushing.June 1, 2008 at 9:53 pm #39923
The tubes mic out at roughly 1.42″ long and .625 OD. Being that they’re wrapped and welded together, they vary a little bit in their dimensions.
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