Conventional Fixtures C-Clampery

[gafftapegreenia]

For the record, the mini-grid in my rehearsal space was built with 1", and some of the clamps on my ETC fixtures won't clamp reliably on *that*, either. I was going to rebuild it with 1.5"

jstandfast's comment was about the fact that one cannot simply remove the spigot on an ETC clamp and insert a piece of 1/2" pipe to make a side arm, it simply won't fit.

Instead of rebuilding your grid (unless you really want to) you can get longer clamp bolts: http://www.mcmaster.com/#set-screws/=qz9phy

 

[Jay Ashworth]

D'oh. Got it.

And that grid is screwed to the underside of wood ceiling joists with flanges, instead of being hooked over the adjacent building steel; yeah, I think I'm better off rebuilding it.

BTW: Does Gafftapegreenia issue entry visas? Or is a passport enough to get in?

 

[TADesigns]

What better time than during the dark days of winter to take a look at refurbishing all of one of one's hardest-working pieces of hardware?

More or less standard parts nomenclature:

Pipe Bolt: 1/2-13 x 3" Cup Point Square Head Set Screw, ~$1.22/each.
Pan Screw: 5/16-18 x 5/8" Cup Point Square Head Set Screw, ~$0.14/each.
Yoke Bolt: 1/2"-13 x 1" A307A Low Carbon Plain Finish Hex Bolt, ~$0.39/each.
Washer: 1/2" Flat Washer
Lock Washer: 1/2" Split Lock Washer
An alternative to the two items above:
Belleville Washer: 1/2" Belleville, .512 X 1 X .039, 1050/1070 Plain Finish, ~$0.76/each.
I highly recommend the Belleville washer instead of the flat and lock washers. I first learned of this due to the Mega-Clamp, which does not have a Pan Screw.


For those wondering what prompted this...I refused to believe the stagecraft mailing list when it was said that 1/2" I.D. Schedule 40 steel (sidearm) pipe would not fit in an ETC C-Clamp and thus Altmans-only must be used. I had to see for myself, and yes Virginia, it's true. [edit: ship said it here on 11/01/07, but the wheat must have gotten lost in the chaff.] I love sidearms, and am very disgruntled at ETC right now, especially since they've kept this a secret from me for sixteen years. I suggest everyone purchasing new fixtures to try to get his/her dealer to substitute a Mega-Clamp at no extra charge.

Can you post where you can purchase Shaft/Stud/Spud/Spigot?

 

[JonCarter]

We used to have "C" clamps that were forged. These were either Kliegl or Century, made in the '40s or '50s. These were the rectangular ones, similar to Derek's picture in the first post in this chain. I've seen these clamps with the rear vertical part bent to almost a 30 degree angle with the clamp bolt collapsing the sch 40 pipe they were mounted on. (These never came loose, but we scrapped them anyway; the clamp bolt was starting to pass beyond the pipe.) We had what you are referring to as the rotation screw (the little one in the side of the clamp) torqued down and permanently left that way; we rotated the instrument with the yoke bolt loosened and then torqued that down. Standard focus tool was the 10" Crescent wrench. (This was in outdoor theatre with 2kW or 3kW Klieg lekos on 90' towers; got windy up there.)

(And no safety cables in sight.)

There were also Capitol "C" clamps. These were cast, and were in a real "C" shape. They were one-piece items, with the instrument mounting part of the clamp having 1/2" male pipe thread. Add a pipe plug drilled and tapped for whatever you wanted to mount or a pipe reducer (1/2" to 1-1/2") with a 2' side arm screwed in. I'd mount one as a side arm and chin myself on it; if the C clamp didn't break we'd use the side arm. Some of them did break.