Building a hydraulic pull tester!

[@climbingtaiwan]

Thanks for sharing some open-source methods! I like how you're exploring different avenues for doing pull-testing, because some individual’s goals, what’s available to them+already have on-hand, where they can carry out tests, etc can all widely can differ.

[@bobbyhutton1989]

Awesome! Thanks for doing all the research and design and sharing it. It used to be more common to use similar hydraulic pullers to remove and replace old bolts before Greg German's ball screw type puller was designed. Really impressive that you were able to design something that compact and cheap.

[@MountainMullet]

Thanks mate! I actually started this by trying to make a screw based puller with a load cell so you could see how strong the old bolt was, but this turned out easier to make. The screw one is nowhere near as strong and is still a work in progress but you'll see that eventually too. Some of the oldest pull test data/ vids on KZbin are from an Aussie guy Mike Law who uses some kind of hydraulic puller but I haven't seen what that rig is. Presumably something bigger

[@bobbyhutton1989]

@@MountainMullet we watched those videos when we where designing our pullers.

[@MountainMullet]

And if you ever saw that old one about how to remove wedge bolts, I believe the tool they use is a smaller hydraulic hole punch. I had no idea what that was until researching this device. Maybe researching is too strong a word... Endlessly online shopping for cheap tools maybe?

[@bobbyhutton1989]

@@MountainMullet greenlee was the brand they used. Super expensive!

[@MountainMullet]

Wow Greenlees! You could almost buy a proper calibrated hyrdajaws tester for that money

[@toolscientist]

Should get less bending with swivel feet. Looks like you have one on your desk. The female threaded versions are better, but they seem rarer and I can't find any that even give a price. It's not foolproof. Had a new guy not pay attention and bend the legs of a hydrajaws, which is a giant pain as they can't be removed when bent. You could try restraining the legs. Maybe several wraps of dyneema webbing for ultralight setup, or a small ratchet strap for less faff. I'd definitely try to get rid of the double nut setup, but don't do threaded holes. Maybe try sandwiching a square nut between 2 alu plates. The bottom plate can be 2mm as it's just there to stop the nuts falling out. Glue blocks of alu (or other square nuts) around the sides of the square nut to stop it rotating.

[@MountainMullet]

Thanks again mate. So you use proper hydrajaws in your work? I can definitely see the refinements they've made to that product and I hope to get one someday. Do you know why the legs are offset? The Hilti tester is also like that. I'll probably just make mine a bit bigger, maybe class 12.8 steel, and maybe offset with an M16 one end and 2xm12 on the other. But it's hard to find and I want to avoid having anything made. I considered leg straps but the legs held up better than expected, and I didn't want to faff with it any more. Also blocks the camera from seeing the "action"

[@toolscientist]

@@MountainMullet Used to - left that job. Not sure what you mean by offset. Do you mean why 3 legs rather than 2, or why the legs don't form an equilateral? I used an older hilti with just 2 legs and it was an absolute bastard, always leaning over if you didn't position it perfectly. I guess non-equilateral is to give it enough space that the feet aren't interfering with the anchor, but keeping it narrow enough to get anchors that are up against a wall. Bigger is better than stronger. You're dealing with buckling, so strength is less important than geometry and modulus, and all steel is 210GPa.

[@MountainMullet]

Yeah, Isosceles triangle configuration legs. More room to access anchor from the sides and also I suspect it makes leveling a bit easier

[@toolscientist]

Oh, btw, it's pronounced clev-is (like clever or Ben Nevis), not clee-vis

[@MountainMullet]

Great. There goes my planned animated spinoff, Clevis and Butthead.

[@toolscientist]

@@MountainMullet Some folk'll never lose a pin, but then again some folk'll, like Clevis the slack-jawed yokel.