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Old 06-16-2012, 10:47 PM
VMFn542bob VMFn542bob is offline
Join Date: Oct 2009
Location: Arizona
Posts: 1,066

Fabricating the MANN Barrel Support Tube
I completed two more support tubes today. (text edited 29Jun2012 - The support tube bears the weight of the MANN without touching the barrel.) These photos illustrate what is involved in making them. (I had 4 blanks to work with. The first was for practice because I had not used a dividing head before this. I came to the metal shop with two end mills and once I was set up I proceeded to cut the slots. When almost all of the slots had been cut in the fisrt tube, the 0.500" diameter 4-flute hollow end mill I was using broke. I replaced it with a backup 2-flute center cut and continued. It was not until I got home I could see a difference. The 2-flute was smaller (0.4375"). No problem. I changed the dimensions on my drawing.)
The tube material is common 16 gage 2 inch diameter galvanized exhaust pipe purchased from Midas Muffler.
Ventilated Support Tube Dimensions

Squaring the ends of the tubes on a lathe

Milling vent slots on a milling machine with a dividing head

Three ventilated MANN Barrel Support Tubes (unfinished)

Three machined support tubes stand between a Folgers coffee canister (used to transport small tools to and from the metal shop) and my book of engineering drawings needed to setup and run the machines.
The tube on the left is unique. In addition to four rows of seven slots it also has one row of 7 small holes on the top. It is experimental as this entire project is.
The setup time for preparing these machines was considerable.
The support tubes still need to be polished, sand blasted and powder coated. That will be the very last thing I will do before putting it all together and trying it out at the range.
I still have a long way to go.

19 June 2012 - Bored slot in support block for the Support Tube Stop flange

2 Jul 2012 - I finished fabricating the MANN Barrel Support Tubes today.
Over the weekend I deburred and polished the slots.
Today I sand blasted them and painted them with GR539 Chrome Powder Coat Color.

Three ventilated MANN Barrel Support Tubes (FINISHED)

Last edited by VMFn542bob; 07-20-2012 at 07:10 PM.
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