ronlaughlin

Spent some time making ventliners from 10-32 x 3/8" 18-8 stainless steel cap screws. It took me 4 tries with 4 screws and 4 #70 cobalt drills to get one made. The screws cost about $0.20 each, and the cobalt #70 drills cost about $3 each. I guess that means the one ventliner cost me $12.80. Then i busted the drill on the next screw, and tossed both the drill and the screw. Then i drilled 2 screws with one dill before i broke it. Then i drilled 5 screws before i busted the next drill. The next drill made it through 2 screws, and then broke. The last ventliner was then drilled, and then i tried to drill another with the same drill, but failed.

The liner on the left is one i made from a long screw, that was cut off, and drilled quite a long time ago. It has a few hundred shots through it and what started out as a 0.029" flash hole, is now 0.030".







What got me started trying to make my homemade ventliner, is when Lehigh raised the price on their liners. After fighting these stainless screws with different types of drill, i gave up, and decided to purchase the Lehigh, but by then they were out of stock. This put me back to making my own ventliners.

The Lehigh ventliners are so very much harder than these 18-8 stainless screws, but stainless resists rusting, which is oxidation, which is a slow flame erosion. It seemed to me that the stainless would do a good job maintaining flash hole size, because it is made not to burn. Lehigh liners seem to resist flash hole oxidation quite well. I would be interested in knowing how many shots it takes to enlarge a Lehigh ventliner flash hole by 0.001". One fella wrote quite some time ago, that he replaced his Lehigh ventliners about every 200 shots, but i would think they should go longer than that.

The flash hole on these stainless liners is 0.028", whereas the flash hole on the Lehigh liner is 0.031". The smaller flash hole works well, and should allow for a long usable life, for these stainless liners.

Muley Hunter

Ever drill titanium?

ronlaughlin

No, have you?

sabotloader

ronlaughlin

If I could make a suggestion, I would suggest a small counter bore or countersink at the inlet of the Vent Liner. This will allow the gas a better path into the Vent Liner, possibly allowing the gas to move more uniformly into and out of the Vent Liner.

ronlaughlin

There is a small counter bore. I made it turning the cutter by hand and holding the screw in my other hand. You couldn't see it, so i guess it isn't enough. I didn't do it deeper because i couldn't figure out how to get er done with the machine. The one on the left is what i have been doing.







After reading your post here, i dreamed up a gunny sack way to hold the screw, and gave it a whirl using the machine. The one on the right is the result thanks to your push.









Thank you for the suggestion!

sabotloader

ronlaughlin

Oh ya! Ron the one in the bottom picture on the right really looks good. That really should give the gas a direct path to where it needs to go...

That picture makes it look very professional!