Options For Field Camera Focusing Hardware?

[brandon allen]

So I built my 4x5 camera using a screw mechanism (3/8" reverse-thread acme screw to be precise). I would have used racks and spur gears, but the only ones I have been able to find are ridiculously expensive (Chicago Gear, etc.) to the tune of several hundred dollars for all the parts I would have needed. I spent perhaps twenty dollars on the parts I used for the screw mechanism (and I have enough material remaining to build at least two more just like it).

For several reasons I would still like to explore the focusing rack option, as I continue daydreaming about starting on a 5x7.

Has anybody found a less expensive source for suitable gear racks and spur gears?

I just have to believe that something else exists out there.

I have even been considering buying a few of the plastic 32 pitch gear racks intended for building science projects and spur gears for R/C cars being offered on eBay. Has this been used before?

Thoughts/suggestions welcome.

[Jac@stafford.net]

Spur gears and so much more here at at McMaster-Carr (http://www.mcmaster.com/#spur-gears).

Browse about and be happy.

[Richard Wasserman]

McMaster Carr always makes me happy. I used to have a business where I bought from them regularly. Of course there was the time I ordered 1 plastic bucket and they sent me 1,000. It was a bit like The Sorcerer's Apprentice in Fantasia with me playing the part of Mickey Mouse....

[Tin Can]

Very timely post, as I want to add mechanical focus to a Century Tailboard. The knob is not working for me.

Only last night I was considering 5 start Acme thread, which give 0.5" travel per revolution. I found McMaster to be too expensive. This maybe http://www.ebay.com/itm/141629722135 http://www.ebay.com/itm/141643805499

Now you mention spur gear and I will look into that also.


Why are you unhappy with your Acme threading?

[Peter Gomena]

My old Rochester Optical Company whole-plate camera has no tracks or threads. It's simply push-pull on the rails and is locked by a simple threaded bolt that pushes a piece of brass against the rail. It maintains good focus and is easy to fine-focus with just a little squeeze of the fingers.

[DannL]

The 8x10 that I use (Anthony & Scovill Champion) also has no gears. It's a very elegant and simple design that works quite well.The camera is a rear focus sliding design, and the rear standard locks into place with a threaded rod (not visible in picture). Small brass plates hold the standard to the rail in finely cut grooves. The intent here is to reduce weight, once touted as the world's lightest 8x10 field camera.

http://piercevaubel.com/cam/anthony/amchampl.htm

[brandon allen]

Very timely post,

...

Why are you unhappy with your Acme threading?

I'm not unhappy, it actually works very well! At 10 tpi I can move the front standard -reasonably- fast, but it does take a little time, fine focus is easy to acheive with such "precise" movement. No focus lock required - front standard stays right where you stop moving it without further input. And the system was quite easy to make.

What I don't like about it:

1) aesthetics - I just prefer the "classic" look of knobs on the sides.
2) bulk - at least the way I did it, the rear standard had to be raised 1 1/8" in order to clear the focusing mechanism and made it almost impossible to design the camera that folds up into a tidy box. And the focus knob protrudes from the back of the camera when it is folded. The design could be altered to reduce this, but max extension would probably decrease (not such a big deal).
3) weight - Kind of +/- here, I THINK focusing racks and rods with spur gears would end up being lighter, but the 8" piece of acme screw wasnt that heavy. So this may not really be the case.
4) ease of use - unless I can get an even coarser thread acme screw (I couldn't find one without going to a larger diameter screw = bulkier & heavier) it takes extra time to move the front standard long distances (~80 turns to get to full extension). Not a deal breaker, but I cant just push the standard forward and let the knob spin. It is much like opening/closing a casement window.

[Jac@stafford.net]

Why are you unhappy with your Acme threading?

Come on! Why would anyone buy from Wile E. Coyote's favorite supplier?

[Kirk Gittings]

McMaster Carr always makes me happy. I used to have a business where I bought from them regularly. Of course there was the time I ordered 1 plastic bucket and they sent me 1,000. It was a bit like The Sorcerer's Apprentice in Fantasia with me playing the part of Mickey Mouse....

:)

[brandon allen]

Spur gears and so much more here at at McMaster-Carr (http://www.mcmaster.com/#spur-gears).

Browse about and be happy.

I know, they have them and they are very expensive! The racks are even more!

[brandon allen]

My old Rochester Optical Company whole-plate camera has no tracks or threads. It's simply push-pull on the rails and is locked by a simple threaded bolt that pushes a piece of brass against the rail. It maintains good focus and is easy to fine-focus with just a little squeeze of the fingers.

The more I think about it, the more sense this design makes!

Where is the tripod mount, btw?

[Jac@stafford.net]

I know, they have them and they are very expensive! The racks are even more!

They are not expensive when considering a build that will last our lifetime.
.

[Jim C.]

I've used Stock Drive Products on occasion to get gears and what not -

https://sdp-si.com/eStore/Catalog/Group/479

It's too bad you decided on using acme screw thread, they're very robust threads but as you said you have to crank it
to set up your extension, a regular machine thread would have probably worked using a push button quick thread nut (http://www.mcmaster.com/#98150a730)

Just throwing this out as an idea, haven't really thought it thru much but treat the acme screw on your camera
like a lead screw on a lathe and make a half nut mech by soldering or welding a acme nut cut in half to a scissor mech.
Pinch to release, slide your front standard out and release to have the nut halves engage the thread.

[Jac@stafford.net]

I've used Stock Drive Products on occasion to get gears and what not -

https://sdp-si.com/eStore/Catalog/Group/479 [... snip great info...]

Great stuff, Jim! Thank you.

[Tin Can]

Acme threads have faster travel per revolution depending how many thread 'Starts' they have. A single 'start' is slow. An 8 'start' will be much faster, some move 1" per revolution, meaning 10 rotations of the handle move the nut 10", yet retains high positional accuracy. Very little lash also.

I have an old Levy Process camera that has Acme screw front focus and rack rear focus, both at the rear. Really handy, but not a Field camera, unless you have elephants. Then it's perfect!

[Jac@stafford.net]

Randy, it would be great if your contributions could be compiled so that the rest of us could find them rather than searching the site which we know is not the best.

Thanks for your help.

j

[Tim Meisburger]

Can you point me to an explanation for metric rack sizes? I am making an 8x10 copy of my 4x5 Ikeda Anba and need to figure out how to measure those racks to order some for the 8x10 (I assume I can use the same size). I have been looking at racks on AliBaba sites and they seem much cheaper than ordering from the US.

[Tin Can]

Can you point me to an explanation for metric rack sizes? I am making an 8x10 copy of my 4x5 Ikeda Anba and need to figure out how to measure those racks to order some for the 8x10 (I assume I can use the same size). I have been looking at racks on AliBaba sites and they seem much cheaper than ordering from the US.

I cannot find a metric description. McMaster Carr has SAE basics covered. http://www.mcmaster.com/#rack-and-pinion-gears/=x21i0g

I don't know how old the camera you are copying, but I do know many Japanese machine tools/tooling and products were "American" sized from USA rebuilding efforts of Japan after WWII, extending well into the 60's. Japanese cars were half SAE, half metric. Perhaps cameras were similar. I would check.

[brandon allen]

It's too bad you decided on using acme screw thread, they're very robust threads but as you said you have to crank it


I don't want to sound like I'm unhappy with my current setup, it actually works very well. The front standard can be mounted in three locations, like a Chamonix, so I can set the camera up with the extension in more or less the correct range. From there it has only required a few turns of the handle to get where I want. If I were using a 500mm lens, then it would be a different story.

I'm thinking about another system more for compactness and the ability to make the camera fold into the smallest package possible and perhaps to be able to fold with a small lens mounted. Regardless of how quickly it operates, you still have a screw running down the middle of the camera's bed along with the associated nut and mounting system. Makes for larger "folded volume" and almost totally prevents leaving a lens mounted.

[Tim Meisburger]

I cannot find a metric description. McMaster Carr has SAE basics covered. http://www.mcmaster.com/#rack-and-pinion-gears/=x21i0g

I don't know how old the camera you are copying, but I do know many Japanese machine tools/tooling and products were "American" sized from USA rebuilding efforts of Japan after WWII, extending well into the 60's. Japanese cars were half SAE, half metric. Perhaps cameras were similar. I would check.

Thanks Randy. I could measure my camera in inches, but I have to order in metric, so I need to understand that system.

[Jim C.]

Tim, check this out on Stock Drives site -
http://www.sdp-si.com/D805/D805_PDFS/Technical/8050T007.pdf

too much math for me, I use gauges to check the gear pitches, they're not cheap new
you can find some inexpensively on the Bay used or new.

[Jim C.]

Happy to share resources.

There is also WMBerg - http://www.wmberg.com/

[el french]

This thread (http://bbs.homeshopmachinist.net/threads/43645-Making-Acetal-leadscrew-nuts-the-easy-way) details how to make Acme nuts out of Acetal. The method works for making half nuts as well. The best part is the nuts have zero backlash.

[Peter Gomena]

The more I think about it, the more sense this design makes!

Where is the tripod mount, btw?

The image shown is the camera with the rear extension removed. This originally was a studio camera, so I cut a piece of 3/4" x 5" maple and drilled some appropriately placed holes in it to anchor it to my low-profile Gitzo head. The maple has one hole with a 1/4-20 insert in it for the tripod nut, and two other holes for other 1/4-20 thumbscrews that attach to two tripod mounts on the original center piece. The thumbscrew I use on the front of the two tripod mounts actually fits through a hole in the front of the Gitzo head, through the board, and into the mount on the camera bottom. It's a bit fussy to set up, but it all locks down well.

[Peter Gomena]

Hmm, looking at my picture again, I'm in error in my description. There is a mount under the front extension and the brass strap in the middle has a threaded hole in it. The front standard is fixed. I put a thumbscrew through the front hole in the Gitzo, through a hole in the maple board, and into the front tripod mount. A second thumbscrew goes through the maple board and into the threaded hole in the brass strap. The Gitzo nut attaches to a threaded insert in the bottom of the maple board. So, there are two attachment points for the camera and the maple board. Not light, but effective.

[normanv]

I used toothed timing belts and pulleys for a 5x7 camera that I built. I salvaged the parts from an old photocopier but they are available new at very low prices.

[brandon allen]

That's another option I've contemplated. For the shafts did you also use reclaimed copier parts or make new ones?

[brandon allen]

BTW, I started a Flickr group intended to showcase pics of the actual camera building process as well as the finished product. Feel free to add images if you have them. I hope it will become a useful and interesting resource for people are building a camera or thinking about a build. Kind of an opportunity to show how you made it all work. https://www.flickr.com/groups/2671577@N23/

[Tin Can]

BTW, I started a Flickr group intended to showcase pics of the actual camera building process as well as the finished product. Feel free to add images if you have them. I hope it will become a useful and interesting resource for people are building a camera or thinking about a build. Kind of an opportunity to show how you made it all work. https://www.flickr.com/groups/2671577@N23/

Very cool design for the lens board shift.

I like you idea of sharing info, but I am so often very disappointed to find dead links to such off LFPF hosts. look back in time on this forum and we have many dead links.

We all mean well, but we sometimes decide to not carry the torch, meaning we close our sites. I have done it.

I vastly prefer we all post any pictures directly to this forum using the 750 pixel limitation as those images will most likely survive us.

Flickr may be fickle. Fate is unending.

[brandon allen]

Thanks!

And you make a fair point. I had started the Flickr group a long while ago (before I started posting here) and just thought I'd mention it. It seems that the threads here are more about the finished product rather than the building process. I suppose there is no law against starting a "Show Us How You Built Your Camera" thread specifically for that purpose.

[normanv]

Brandon, I can't remember what I used for the shafts, I just used whatever was available. The copier shafts would have been good as they were stainless steel.