Calumet C1 knob specification help

[OKAROB]

Can someone please give me the specification for the two knobs on a calumet C1 8x10 camera that hold the front and rear standards together when the camera is folded？ I would like to see if I can get a machinist to make a few for me. These are two small knobs on the bottom of the front standard that I think screw in to hold the pins from the rear standard. I someone could take a picture and tell me the size thread and the dimensions of the knob it would be much appreciated. Is there any mechanism to keep them from falling out when moving the camera around? Thanks for you assistance!

[Tin Can]

I will see if I can shoot them a little later.

They always fall out as they need to almost totally unscrewed.

They are usually the same size as the front standard elevation/rise lock screw.

[OKAROB]

Randy and anyone else, I recently sold my C1 and didn't realize they were missing, so I am trying to see if I can have a few made to replace them. So if you or anyone else could help me that would be much appreciated.

[OKAROB]

One last question are they made of aluminum? Or steel?
Thanks again everyone!

[Tin Can]

Steel 4-40 thread. Look here (http://www.engineersedge.com/screw_threads_chart.htm).

118050

[Tin Can]

Don't make them from scratch. Buy some bolts and have a welder attach a knob or large nut. May as well go with stainless.


Randy and anyone else, I recently sold my C1 and didn't realize they were missing, so I am trying to see if I can have a few made to replace them. So if you or anyone else could help me that would be much appreciated.

[OKAROB]

Randy, thank you very much, that is perfect!!

[Jac@stafford.net]

Don't make them from scratch. Buy some bolts and have a welder attach a knob or large nut. May as well go with stainless.

I replaced the lockdown knob and screws on my C1 using inexpensive ACE Hardware threaded rod (a bolt with no head) and their knobs held on using red loctite.

(I was surprised when the clerk asked what I was making, and I said I was repairing a large view camera. He replied, "We had drawer of C1 parts at the studio.")

[mdarnton]

Google 4-40 threaded thumbscrew. Lots of options, ready-made.

[Jim Jones]

Google 4-40 threaded thumbscrew. Lots of options, ready-made.

1/4-40, not 4-40? Better yet, do as Jac suggests. I might use epoxy instead of Loctite, though.

[mdarnton]

Randy's photo looks like 4-40, just as he says. My local hardware store has these in the little drawers where the O-rings and small parts are--this is not a rare item, and there's no reason to kludge up a Frankenfitting.

[Tin Can]

McMaster Carr has lot's of knobs alos and no order is too small.

[OKAROB]

Thanks everyone. Yes from the photo it does look closer to a 4-40 thread. The ruler is in 32nd of an inch increments. I did find the thumb screws listed on amazon. can anyone confirm it is a 4-40? it could also be a 6-32?
Any help would be appreciated. Thanks

[Tin Can]

In the picture the ruler is metric on the near side and inches on the far side. My pitch gauge shows 40 tpi and it will not thread into 4/32 nuts.

I think these were after thoughts as they are poorly implemented. The casting is too thin in that area, for no good reason, and one needs to unscrew them almost all the way out.

The same screw type is used in several after thought locations to lock rise. I have owned 3 C1's and the rise lock screw was in 2 different locations and a 3rd did not have it.

[David Lindquist]

Some used a 5-40 screw, see my post #24 here: http://www.largeformatphotography.info/forum/showthread.php?110514-Calumet-C-1-improvement/page3&highlight=Calumet

Then in post #29 gth reports his uses a 4-40 screw.

David

[Tin Can]

Retap metric and be done with it.

[Michael Cienfuegos]

Just go to the hardware store and buy a few 4-40 screws. If they don't fit, then follow Randy's suggestion. If they do fit, you can order a few from McMaster-Carr and be done with it.

[OKAROB]

Thanks everyone, especially Randy for all of the information! That is interesting that it could also be #5 screw. It is enough to drive you crazy. I appreciate the quick responses and help that everyone on this forum gives.