Perfect Union banner
1 - 13 of 13 Posts

·
Registered
Joined
·
300 Posts
Always remember, 'tight is tight but too tight is loose again'. I think it's somthing like 15 inch/lbs? Hopefully someone with a better grip on reality will chime in.
 

·
Registered
Joined
·
9,786 Posts
Mark I used to recommend 17-24 in/lbs as that is the spec for that wet fastner (loctite) in aircraft. However My gas block moved forward, on the barrel, and gaulded the gas port bushing. Mike knifong recommends 2-3 ft/lbs i.e. 24-36 in/lbs. I would go with that. If you don't have a torque wrench, tighten evenly, but NOT screw stripping tight. Also use a feeler guage to keep the gap between the blocks even. Some members have seen a slight improvement in accuracy just by doing this.
 

·
Registered
Joined
·
103 Posts
In consideration of the fact you are torqueing with an allen wrench I just gave it all I could without twisting the allen wrench permanently. I have some sockets with allen wrenches (hexes) in them and an inch pounds torque wrench--but why worry, short of stripping the threads how can you overtorque? The wrench will tell you when to quit. Give'r hell!!! With an allen wrench you can undertorque but not overtorque, you'll twist the wrench first!!!
 

·
Registered
Joined
·
716 Posts
When you are dealing with a tin-foil barrel, this is not the case - I would not doubt that you could noticably pinch the barrel by max-torquing all 4 screws.
 

·
Registered
Joined
·
103 Posts
OK. I was just going by the fact that it took a 65 ton press to put the sleeve on a mortor I was making--and the sleeve was red hot. The press fit was .004 and the press groaned when it was putting it on.

I'm just a home shop machinist and was saying how I do (did) it. Maybe I could put a jug choke on the barrel just by clamping it??? Live and learn:D
 

·
Registered
Joined
·
49 Posts
I don't know exact ft lbs, but I can help with the way I handle Mini's that I work on. What I do it put antisieze compount around the barrel and on the inside walls of the gas block that the barrel sits in. I do this for several reasons, but number one reason is that I know for a fact it shows up on the paper (makes it group a little better). I then use my thumb and index finger with the short end of the hex wrench to turn the longer end in the screw. I then tighten them as one would tire wheel lugs going opposite caddy corner until they are all tight.

Hope this helps.
 

·
Registered
Joined
·
216 Posts
Billc: ...to put the sleeve on a mortor I was making...

I hope you are talking about a motor, not mortar...

V.
 

·
Registered
Joined
·
103 Posts
Yes "V"--Thank You so much--I needed that this AM. Built a 1/4 scale coehorn (sp) mortar that was typical of the civil war era. Shot juice cans in it and was always a hit at blackpowder shoots. :D
 

·
Registered
Joined
·
9,786 Posts
satan is right on. If over torquing the gas block screws, can compress barrel shape affecting accuracy.

Billc. For example, I used to rebuild auto engines, I made a few extra bucks by this trick. I would bet $1, I could expand an inside micrometer in a cylinder of a cast iron engine where it would support itself, then by using only my two hands, distort the cast iron engine block enough where the micrometer would let go and fall down. I've never lost that bet!

Billc, I hope your mortar isn't anything like my "cajun worken buddie", who built a potato gun , and it blasted a hole clear thru his house?
 

·
Registered
Joined
·
56 Posts
Cheap trick, and it will work. Just take your Allen wrench and on the long side, measure off one inch. Mark with tape. evenly install the gas block and snug up the screws. Get a spring scale, and at the tape mark, place the hook. Then pull to the specified weight you want. If you don't have a spring scale, just weigh your mini and adjust the measurement on the wrench accordingly to get your torque. then let the weight do the work. Carefully, I might add! Don't drop it. This will torque the screws evenly.
Spud :usa:
 

·
Registered
Joined
·
716 Posts
cajungeo-

Potato cannons are awesome. My bro has it down to a science - combustion chamber-to-barrel volume ratios, ignition spark location, etc. He made me one for X-mas a couple years ago - about $20 worth of parts. All PVC.

Launches potatoes 300-450 yards. Its a blast taking a couple boats out on the Bay and launching at each other. Coast Guard would probably beg to differ.

One can of Aqua-Net, a 10# bag of taters and you're good to go!
 
1 - 13 of 13 Posts
Top