29) The clamp is often neglected. Why do factory
send a ½-13 grade 2 screw that’s only 3/4" long with the
fixture? Hmm, loose 1/8" worth of lock washer, and another 1/8" worth of
yoke and that’s only ½" worth of thread within the
C-Clamp. Not enough nor a strong enough screw in my opinion. Even if 7/8" or 1", it’s still not long enough. Most C-Clamps will accept up to a 2" long screw, use it. Where possible, replace all
C-Clamp bolts with at least a 1-1/2" long screw of Grade 5. No the grade 2 won’t break, but as you move up in grade you also move up in rust resistance.
Oil your screws and clamp. Oil without mechanical locking help might make something come loose easier but in this case you are using a lock washer so it’s not coming loose. While it is acceptable to use both lock washer and washer on a clamp, the lock washer is what is most important in preventing the
bolt from coming loose.
Than again, you need a certain amount of movement without it coming loose. Add a fiber or nylon washer between
yoke and the standoff T-nut part of the clamp. Such a free bearing surface will allow you to tighten the clamp, yet also allow the clamp to pivot some without anything coming loose. As with most screws, 1/4 turn past finger tight is proper tension with a 6"
C-wrench. You don’t need a 10" or larger wrench to tighten a screw. If it comes loose with use re-tighten it or look at the user if more than just a little loose.
The pan-lock set screw on the other
hand is of a different material. It needs oil or it’s going to rust. Use or or it will rust in place. Gorillas will over tighten and deform the standoff or even break it. Make them extract this screw - it will be a learning experience in something that often cannot be removed. Can be but not always. If you oil and use this screw, it will be by far easier to extract than something that is not used much and rusts into place. Should your standoff get divots in it that allow the
fixture to slip some, grind away what you can so it’s
flat again and where possible spin the standoff away from that area. Otherwise you might be able to get replacement parts. Much less if you have built some side arms, you will have extra parts.
The pipe clamping square head set screw needs to function properly. It often will get dings, need to be removed for the 4" version to be installed so it will clamp to smaller pipes or walls or other wee
bit of problems. Never remove this screw without examining the screw. Might be bent and not working properly but look at the tip of the
bolt first. When that gorilla with the 10" wrench dogs down the clamp to the pipe, they will deform the tip of the
bolt. When you try to remove it from the clamp, the
bolt often is harder than the cast
iron of the clamp and it’s removal will destroy the threads of the clamp. That’s unsafe. Should you have a damaged tip, re-tap, or cut it’s tip off than re-tap. Then extract it. Should it be a bent
bolt, cut it off at the
bend and remove what you can near where it exits the clamp. Attempting to remove a bent screw from the clamp otherwise will also strip out the clamp. Replace with the same brand of set screw.
In assuming a
C-Clamp, the technology of the casting has improved much over past years. They still are not perfect. If your clamp no matter if bent steel, cast
iron or stamped or cast aluminum shows any sign of bending, replace the clamp. Do not allow in service a bent clamp. While more frequent that it will
bend instead of break, you still don’t want to continue using it or it potentially will break.
Be watchful of
stock looking cast C-Clamps that have a sort of pint/
varnish coating on them. They do not come from any manufacturer and instead from china. Such clamps that have this seeming
varnish coating are using much cheaper metal in the casting and need that extra coating to prevent the rust. Such clamps with the cheaper metal will break and strip 10x faster than anything a name brand even 40 years ago was making. It’s also something that should it get hit might fail instantly at any
point. Have a look at the clamp for hair
line cracks, but with these cheap C-clamps you might never see the hair
line clamp. Do not use some off shore other than name brand clamp. No name on the clamp,
varnish like coating to it, toss it in the trash.
Such clamps came on the market say 10 or 15 years ago and only lasted a few years by way of the theater supply market looking for a cheap alternative. I doubt they are still available, but thousands have been sold over the years. Be watchful of such things.
