Besseler Negatrans

[Charles O'Connor]

Just replaced the belts on my 120 carrier and the 35mm. The O rings from Grainger DASH 167 (35mm) and DASH 175 (120) fit and work perfect.

 

[Philippe-Georges]

Thank you for the tip, but could you please geve some more info about Grainger DASH, so I could find these in Europe, or an equivalent?

 

[Nicholas Lindan]

Do you have the ring's width and durometer? Or Grainger's part number, I found 41UK65?

 

[koraks]

https://www.grainger.com/category/hardware/o-rings-and-o-ring-kits/o-rings?attrs=Dash+Number%7C167%7C175&filters=attrs

So 167 is a 7" nominal inside diameter, 175 is 9".

The O rings

Which ones? I get different materials and the ring thickness seems to vary a lot, too.

 

[xkaes]

FYI, Beseler made different versions of their Negatrans -- at least for the 35mm model. I have no idea if the belts vary, but they might.

 

[Charles O'Connor]

My 35mm does not have any model numbers. Grainger.com, DASH is the way O rings are listed in the U.S.A. I think it is part of an aerospace specification to find part in a table. Not sure if adopted globally.

 

[Charles O'Connor]

Note: These are for a Beseler 45 enlarger. I used rough measure of diameter then c/pi to get diameter. Thickness of ring in mm was measured by laying it on ruler. Nothing precise, but close enough.

 

[koraks]

View attachment 372286
My 35mm does not have any model numbers. Grainger.com, DASH is the way O rings are listed in the U.S.A. I think it is part of an aerospace specification to find part in a table. Not sure if adopted globally.

Brilliant; these seem to be them:

https://www.grainger.com/category/hardware/o-rings-and-o-ring-kits/o-rings?attrs=Dash+Number%7C167%7C175~~O-Ring+Material%7CBuna+N&filters=attrs

This should help people elsewhere in the world select a suitable alternative.

 

[Charles O'Connor]

Do you have the ring's width and durometer? Or Grainger's part number, I found 41UK65?

I chose 70 shore A based on how the original felt in my hand. Plus its one of the most common hardness levels in similar uses such as audio/video transport mechanism.

 

[mshchem]

I chose 70 shore A based on how the original felt in my hand. Plus its one of the most common hardness levels in similar uses such as audio/video transport mechanism.

Well done, any tips on the installation? This is great information.

 

[mshchem]

I just ordered a pack of each. My units are still working but could snap anytime. I use these occasionally. Good to know that the 35mm will go half frame for the new Pentax

 

[Charles O'Connor]

1. Go slow and gentle. The roller springs look fragile. Brass I think so lift gently.
2. Remove the glass if present. My 35mm does not have glass.
3. The gasket slides out to the right and then up. So remove the front screws of the leaf springs to allow it to slip out under the window.
4. The 35mm has a slider to cover the frame number. Be sure end is outside the cover when you put screws back.
5. There is some protectant on the gasket. I wiped it off but it does not appear to transfer onto the negative or cause issues if you leave it on.
6. If the gasket rubs a bit then releases as you turn it check the 1/2 inch rollers are seated properly. It happened on my 120 at first with one of the rollers was upside down. Good news is it still worked normally and the positioning was precise for the negative. If the cover was on I would not have noticed it.
7. My second 35 rolls perfectly forwards but requires multiple turns in opposite direction to move back. I cannot figure out why but ultimately decided I prefer it this way as it allows very precise positioning. If bulk move needed pressing on the gasket while moving thumb wheel moves it.

Note: The 120 is same design but fewer rollers and a glass plate.

 

[koni56]

Merci pour l'astuce, mais pourriez-vous s'il vous plaît donner plus d'informations sur Grainger DASH, afin que je puisse les trouver en Europe, ou un équivalent ?

bonne soirée
j'ai trouvé des joints toriques qui s'adaptent aux negatrans pour 23cii 24 36 la

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