play within the bayonet connection

[JensSchroeder]

Hey Richard,

 

Good idea with the tape and the mating pin holes. Thanks a lot.

I had issues with my XCS / PRO interface too.

Rotating it 180 magically fixed it. I do wrap the threads in PTFE tape and also poked a couple of tiny bits into the holes where the 3 mating pins insert, and it's all solid now.

I don't take it apart ever, I fear it won't go back as nice...

Never got to the bottom of it. Tolerances between different manufacturers.

Check every so often everything is very tight with the post tool and a plastic hammer.

R

[JensSchroeder]

Thanks again to everyone. Needless to say that I love this forum with all the great colleagues. Your advices had been very helpful. I contacted Greg too and he recommended similar solutions and presented me options between no-, low- and high-budget.

To keep you updated, I rotated the J-box 180 degrees, then I took a special plumber sealing ring which even gets a better fit with a little water and put that ring on the side of the j-box where the mating pins are. Presently everything seems to be rock solid and the fixing ring doesn't touch the post anymore. I'll try out the sled next week and hope it stays vibrationless.

Nevertheless I ordered a new, thicker retaining ring.

[GregBubb]

There are multiple issues that I think are being discussed here. Both of which I am very familiar with. Pro manufactured two different height knurled locking rings. The first locking rings are shorter in height by about .040" than the current knurled locking ring. These rings were on all sleds they made for about the first 6-7 years.

 

These are the two rings that hold the center post to the upper camera platform and lower aluminum housing. About eight or nine years ago, Pro increased that height which prevented original XCS posts with Pro mounts to fit firmly together. I then immediately redesigned the mount so that is no longer an issue and will never be an issue. When Pro went to the thicker mount, they completely stopped making the older mount for all their owners and only provide the newer version.

 

There are really three options for a permanent fix if you damage your older knurled rings.

The best option for resale is obviously to change the post ends in the 2" carbon fiber post.

The second option would be to take your knurled ring to a machinist and shave off .040". I would take .020" per side -0/+.005.

The last option is a .050" spacer that you can actually stick inside the knurled ring which allows a tight fit.

 

I think the second issue is one that I have seen more than a few dozen times and can only assume Pro is aware of it. What a few other operators here are thinking may be related to the first issue. It sounds like James is speaking of this very thing.

 

For those who are unaware, when you mate a Pro post to the upper and lower housing the aluminum post doesn't actually touch the aluminum housing of the mating component. The conical pins actually are designed to carry the load, and there is approximately a .010" gap between the two aluminum components.

 

What I have seen and measured is an occurrence that happens when one or two stainless steel pins in the upper camera platform (most likely the culprit), or lower aluminum housing gets pressed into its own housing causing a scenario like a three legged barstool with one short leg. The end result of this will cause the camera platform to shift under weight resulting not only in movement, but your sled will not maintain balance.

 

This movement most of the time cannot be seen. It is moving in thousandths of an inch and is almost impossible to see, but it can be measured.

This small amount one may think is insignificant, but when you are talking 20 and 30 lb. plus cameras it will have your sled sitting at a 45 degree angle or more.

 

Here is a quick test to show how little a few thousandths of an inch will throw off a sled. Left to right balance adjustment is a 10-32 threaded shaft. One full revolution moves the camera platform .031". If you balanced your sled and moved your inching knob 45 degrees, you just moved it .0077". If you move it only 22.5 degrees, that is .0038". You can see how your sled reacts to balance when you turn your inching knob 22.5 degrees after it is perfectly balanced.

It very difficult to see .004" movement, other things are flexing that much already with a 30 pound camera.

 

Stay level.

Greg

[JensSchroeder]

A big thank you to Greg / XCS. He could have sold me the expensive version for my problem, means 2 new threads for my XCS post but he offered me the option with 2 snap rings and a ring plier for a few cents. Now everything is rock solid and I'm looking forward to testing it out.

[Alec Jarnagin SOC]

Glad to hear it Jens. Bravo.