Hey /diy/,
I want to use an old scissor jack to make a rudimentary press. I have some scrap ~1.5" diameter, 1/8" thick steel pipe that I'll be welding into a rectangle to make the frame.
What I'm not sure about is how to fit the sides for maximum strength. Should I use saddle joints in tension (1) or shear (2), or should I just miter the corners (3)? If it makes any difference I'd be using a harbor freight flux cored wire machine. Thanks for any advice.
>>1020030
First thing to do would be to determine the pressure your press would see. Then determine a safety factor for design and see if the surface area of your schedule 20 our whatever pipe would sufficiently withstand that pressure. To calculate this you would determine the total cross section area of the pipe wall and the tensile stress of the material if known. If not known you could just use 40k for carbon steel.
>>1020030
Also I would go with the saddle style fit-up just as a personal preference. You may also look at attaching strong back to the press to prevent deflection vertically of needed. Not sure still what pressure you would be looking at. I successful made a press/punch out of some scrap I-beam years ago and successfully punched 13/16" hole through 3/16 plate. This was powered by a bottle jack. Good luck.
>>1020030
Welder here, go for saddle if all materials are the same dimension, and add fish plates to beef up your welds. Fish plates are just flat plates laid over the weld and fillet welded all the way around.
>>1020030
Welder guy again, second suggestion is to use I-beam instead of pipe if you are already buying material. Then fit it like drawing 2.
>>1020089
I reread you post, 1/8 wall pipe seems a little thin, but with a scizzor jack it might be enough. For pipe you absolutely must cope them to fit eachother, otherwise you cant weld all the way around. Fish plates on the front and back of the pipe, and maybe even gussets on the inside corners of the joints. Just a right angle triangle of steel with a little piece of the right angle corner taken off to fit over your weld.
>>1020089
First tack pipe together, tack on gussets once its squared, weld pipe first, make sure you knock enough off the gusset's corner to weld around the pipe. After pipe is welded, do the gussets. Then smooth the weld off flush where the fish plates will go and tack m weld them on.
>>1020093
Pic turned on me, make sure the fish plates are parallel to the way the jack pushes. To clarify, the left section on the pic is the top
>>1020209
If the force to be applied will be straight up using jack, I don't see how gussets help anything. My concern would be the thin tubing bending in the center where the force is. "fish plates", gussets, and saddled joints will not mitigate this. It would require a strong back in the form of flat bar on the top and bottom where the force is applied. Truthfully pipe is not the best form of steel for this to work properly. If your intention is too only utilize a portion of the jacks rating then it may be fine. I'm the guy that built something similar with scrap I-beam years ago.
>>1020077
The saddled joint, if properly welded, would yield the same strengths no matter which configuration you decide to fit the members together.
>>1020433
A saddled joint would be fine either way, the fish plate would work better perpendicular to the forces applied.
>>1020431
The gussets cause less of the length of the pipe to easily bend, making a stiffer design. Steet lights use the same arched shape on a corner. The same design stiffens the joints on telephone poles.
>>1020030
Check welding forums for many DIY press and bender frame examples.
A press is an answer to what you want to press.
BTW I collect scissor jacks, slather anti-seize on the screws, and use them to position work prior to welding and to lift/position all sort of things. I have plenty of jacks but scissor jacks work in any position.
I suggest collecting truck jacks. The post jacks off Fords work very well too.
