Calling Tachihara Users, re: washers and cams

[Ulophot]

I have asked here before about a source for nylon washers to replace the steel ones used under the cams that lock the front standard of the versions of Tachi 4x5 Hope similar to mine. None I have found anywhere is close to sufficiently thin. A new thought just occurred to me today, however, and I would like to ask if anyone has a model using nylon washers—reportedly used in at least some of the later production runs—and would measure the distance of the post base to the hole for the screw that holds the cam on; perhaps the hole was located higher up on the nylon-using models to allow a thicker washer. About the thickest steel one I can use is 0.2 mm, and I am currently trying out a 0.05. For my camera, the washers inner diameter is 5mm; the washers I have (Japanese ones from a model/hobby shop) have an outer diameter of 7mm.

[GRAYnomad]

I can't remember what mine uses, I'll look later and report back.

LATER: Nope, I have what look like stainless steel washers.

EVEN LATER: Actually I just had a closer look. There are 3 washers, in total 1.13mm thick.

[Ulophot]

GRAYnomad, thank you for looking.

[Heroique]

I have a late model Tachi 4x5 with white nylon washers.

However, the washers beneath the two cams are metal. (Are you sure cams ever came with nylon washers?)

In addition, it looks upon very close inspection of each cam, that there are actually two independent metal washers on top of each other. (Perhaps two thin metal washers, since the manufacturer didn’t think just one was thick enough?)

Just curious, but did your camera come with metal washers? And why are you trying to change them?

One idea: Do you have nylon washers on the other parts of your camera? (My Tachi's nylon washers have different diameters and thicknesses.) You might try pulling one of these to see if it’s the correct size for the cams and thin enough to work. If yes, maybe take it to the hardware store and see if you can get a couple more.

[Conrad . Marvin]

If you can find fiber washers, they are much more secure than nylon and don’t slip like steel. I changed a couple of steel washers that were on the focusing stops on my Ebony 4x5 and the focusing mechanism doesn’t move when I don’t want it to anymore. But, they weren’t easy to find and I glued one inside another to get a good size.

[Conrad . Marvin]

McMaster-Carr sells them, but you have to buy packages of 100......$3 -$4 ish. My camera was worth that.

[GRAYnomad]

...In addition, it looks upon very close inspection of each cam, that there are actually two independent metal washers on top of each other. (Perhaps two thin metal washers, since the manufacturer didn’t think just one was thick enough?)...

Three on mine, I wonder if they use multiple thin washers as shims to adjust for differences in each camera.

[Ulophot]

Heroique, It's possible that the report I received about nylon washers with the cams was not correct. My camera, second- or third-hand, came with metal. The camera has clearly been treated a bit roughly by some owner, and I had to send it to Richard Ritter to relieve excessive tightness in the focusing. The cam washers were bent up and not holding very well, which is when I searched and found the hobby/modeling shop not too far away that carried the selection of paper-thin washers I have now. As indicated, I am trying out the 0.05mm ones on the front standard now to see whether they work out better than thicker ones. I wonder if there is a way to treat the washer surface to give great grip without damaging the cam.

Conrad.Marvin, I checked M-C. Thanks for the tip. I have used them and Grainger for other supplies on occasion. Unfortunately, I don't see any thin enough.

[Heroique]

I am trying out the 0.05mm ones on the front standard now to see whether they work out better than thicker ones. I wonder if there is a way to treat the washer surface to give great grip without damaging the cam.

Maybe you can try stacking two or three of your .05mm washers on top of each other?

3 x .05mm = .15mm … which is a little less than the “thick” .2mm washer you’ve tried.

About treating the washers, can you lightly score them with fine sand paper (or apply scratches with a threading needle) to create greater friction between the surfaces?

[Ulophot]

I ordered some Delrin and nylon sheet, but both are too slippery, and the Delrin is too thick anyway. I have tried stacking two 0.05mm washers, and initially, at least, the grip appears to be somewhat improved. Thanks for the suggestion. I'll see how it goes.