Monorail Problem

[bvy]

Is there a trick to adjusting or repairing this large format camera standard? The clamp doesn't have a good grip on the monorail. When I turn the wheel (to adjust the standard/focus), it start to move then slips. I suspect the nylon guides and wheel. It works fine on the extension rail, which I find odd. See pictures. I appreciate any ideas. Thanks.

 

[Jon Shiu]

Could it be that your main rail is damaged?

Jon

 

[ic-racer]

Try cleaning the rail to remove any trace of grease or dirt?

 

[AgX]

Once greasy nuts are excluded from being the problem, you should turn to the driving wheel.

You might exchange it, or set the whole axle a bit deeper into base of the standard as long as the springs still yield pressure on the axle.

 

[bvy]

Thanks. The rail is clean and undamaged.

There is some grease on the wheel axle, but not on the wheel. It seems like the wheel could be set deeper into the track and/or the clamp could be tighter around the rail. But the two clips which secure the axle and wheel (shown in the second picture) are completely tightened, and I see no other means of adjustment.

I wonder if there's something I could apply to give the wheel better traction.

 

[removed account4]

there used to be a product i bought when i had a recording lathe. it was applied to the belt and gave it traction.
maybe an electronics store might be able to help you, that is where i got the stuff when i bought it

 

[AgX]

You could cut out two puntured discs from fine grinding paper, glue them together and set them onto the axle at one side of the drive-wheel.

 

[AgX]

The final solution if nothing improvised should work would be having a new wheel turned out of Polyamid.

The ideal wheel would be double-wedge shaped.

 

[John Koehrer]

Remove the springs in picture 2 and put a shim between the axle and spring. A coke can will be happy to make the sacrifice.

Doh! I am assuming there's room beneath the wheel to be displaced. If not see AgX's reply above.

 

[bvy]

This is a really strange camera. I was curious why the rear standard would move as expected on the extension rail, but have no traction on the main rail. Seems the tracks on the extension rail have some sort of abrasive applied (on the sides of the track) that gives the standard good traction. This is absent on the main rail. I'll look closer later, but I can't tell if something was applied to the extension rail, or wore off of the main rail. Is there something I can apply? John, I know you mentioned something. I'll have to look...

 

[AgX]

I doubt about the abrasive. More likely both rails are extruded to different dimensions of the slot and thus do not match concerning the driving wheel.

 

[bvy]

I doubt about the abrasive. More likely both rails are extruded to different dimensions of the slot and thus do not match concerning the driving wheel.

That makes no sense to me (though I'm not saying it's not the case). Why should the rear standard only work on the extension rail?

 

[AgX]

Because the rails are of different dimensions.
Variations between batches may be one reason. More likely though is that your primary rail has both that driving wheel and that slot worked out. The extention rail still has a newer slot.

For a definitive solution I would set the axle deeper, still maintaining spring loading on it. But this requires mechanil skill on your side. Or I would exchange that wheel.