Rack and pinion for 20x24

[Fragomeni]

I’m working on a new 20x24 camera and I’d like to build in a rack and pinion for rear standard focus. Does anyone have any ideas where something applicable might be found or how to source? It isn’t the end of the world if I can’t find it and it becomes a fixed rear but it would be nice. Any ideas appreciated.

[Oslolens]

Something like this, ebay item 333941702654
W. M. BERG HEAVY SOLID BRASS SPUR GEAR 20 PITCH 24 TEETH PINION FOR MOTOR SHAFT

And this 294228484531

These will not fit together I believe.


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[LabRat]

Maybe rack & pinion not needed???

I made a camera that standards just slid on smooth metal to teflon to wood surfaces with a precision T-slot underneath where guide rollers kept it moving straight and a lock... Another locking block with a threaded rod that threaded into base of standards had a knob to turn to focus pushing/pulling...

You would open up camera, slide standards to about correct positions, lock down screw block, and turn focus knob for fine focus... Works well, and much cheaper/easier to make...

Sorry, no pix as camera is in deep storage now. :-(

Good luck!!!

Steve K

[Richard Wasserman]

Might any of these work?

https://www.mcmaster.com/racks-and-pinions/

[Steven Tribe]

Many continental large format cameras used a central long ACME thread with an attractive end brass turn handle and a fixed threaded brass block at the base of the rear standard. Obviously, both sides of the standard run in slots and the ACME threaded rod is allowed no movement.

Lots of lengths available. There would be some amateur “mechanical “ work necessary to add on the turn handle and the interior non precision bearing.

[Tin Can]

Japan and USA also

As I have posted I am working on AF screw drive using things like this with stepper drive

for AF Studio camera conversion

https://www.amazon.com/BallScrew-SFU...7FX4GHTK&psc=1

https://www.amazon.com/gp/product/B0...LB7Y72U0&psc=1

[Fragomeni]

I don't have the equipment for machining or making any kind of precision T cuts or anything like that. I make all of my cameras using fairly basic hand tools. I think the rack and pinions from McMaster that Richard linked may be what I'm looking for if I go with rear focus. I matching set from them would make a fairly straight forward job of it.

Thanks for the replies all. Much appreciated.

[Tracy Storer]

24 pitch, 20° pressure angle is probably a good size. The face width of the rack and pinion / spur gears is typically 1/4". If you are in EU, then you might want to source metric gearing which is measured differently ("Module" rather than "pitch"). Wikipedia has a good page on gearing.