I saw the thread on spring compressors, and I have been meaning to build one myself. I have taken apart a lot of guns using just body weight and muscle power, along with some sketchy techniques. But sometimes you just need a 3rd or even 4th hand to get everything aligned. Most screw compressors don't have enough travel, but this one should. I think my total investment in this is less than $40, not including the bench grinder - which was the only significant power tool I used.Pittsburgh brand 3/4 Pipe Clamp kit - $105' long, 3/4" pipe from HD/Lowes - $10Great Neck 8" C-clamp - $ 83/4" pipe cap - $ 11-1/8 spade bit, plywood scrap, etc - $10 ?So, this is what I started with. If I had planned it out better, I probably would have grabbed a Pittsburgh brand C-clamp but it looks like China only has one thread pitch. First step is to drive out the roll pin highlighted by the red arrow. That will allow you to unscrew the "too short" piece from the clamp.Unscrew that and then compare the thread pitch to the C-clamp before you go farther. Like I said, I got lucky and mine matched.Once you're sure that's going to match, you can extract the screw from the C-clamp. For mine, I just applied enough force in the "unscrewing" direction to spread the crimp at the bottom of the piece highlighted by the blue arrow in the first pic. I'd imagine that most $8 C-clamps will yield in the same way, but YMMV.Next is comparing the depth of the unthreaded part of the pipe clamp screw to the C-clamp piece, as well as the retaining groove for the roll pin. Reshaping it took less than 5 minutes on my very lame Ryobi 6" bench grinder. And it's not gonna win any awards for finish quality.BeforeAfterWind the new screw into the top of the clamp and reinsert the roll pin to attach to the slider.Last bit is epoxying some 3/4" plywood scrap to the sliding part of the pipe clamp to provide some protection for barrel crowns, pivot forks, or whatever ends up down that end. Mine has a shallow 5/8" hole in it to provide a recess for a barrel... but that's only because I had a 5/8" Forstner bit from another project.And that's about it. I'm sure that there are things that can be done to keep things better aligned, etc... but this cost less than $40 and took me 30 minutes tops, although I am giving he epoxy overnight to cure. I probably have to say something about "use at your own risk" or "not responsible for injuries", etc... but if you've been doing things they way I have, this is probably a step up in terms of safety.
You refer to the Pittsburgh brand of pipe clamp kit. Mine are all PONY/Jorgensen brand. I'll have to check and see if there is any difference on the thread pitch.
Not exactly cheap but I use a padded 6`0" Groz sash clamp.........https://www.woodcraft.com/products/groz-60-t-bar-clamp
However, this should be posted in the Accessory Gate. Perhaps should be made a sticky?