This article suggests the rollers should be 5/8" diameter:
http://www.ohio.edu/people/schneidw/..._bearings.html
However, my enlarger has 3/4" rollers. They are shot, and need replacing. There is some adjustment available if the rollers are not exact, but if the rollers on my enlarger have already been replaced with the "wrong" size, then I might already be almost out of adjustment. Should I switch to 5/8" rollers per the article, or match the 3/4" current rollers?
Science is what we understand well enough to explain to a computer. Art is everything else we do.
--A=B by Petkovšek et. al.
Mine are also 3/4" on DII.
my black and white photos of the Mendocino Coast: jonshiu.zenfolio.com
Thank you for the info. Probably, the design changed slightly throughout the years, so maybe some enlargers have different sizes from the factory.
I am also wondering about one other thing. The article suggests using flanged bearings, mimicking the flanged bushings that come from the factory. The purpose of the flanges would seem to be to guide the enlarger head along the rails. However, when I took mine apart I noticed the plastic rubbing blocks on each side of the head that are adjustable. It seems like these blocks are what keep the enlarger head located on the rails, making the sloppy plastic bushing flanges redundant. The purpose of the bushing flanges is probably just to keep the bushings located correctly. I can save some effort upgrading to bearings if I don't need flanged ones, so I think I will use un-flanged bearings andd keep them in place by some other means like a pin or even loctite. Input is appreciated.
Science is what we understand well enough to explain to a computer. Art is everything else we do.
--A=B by Petkovšek et. al.
The rollers on my DII are also 3/4''. When I read this original article in 2005 I ordered the parts and installed them and it works really well. Not very expensive and a pretty easy job.
The parts in the article are 7/8" diameter. Based on what I am reading there is enough adjustment available to take up the 1/16" difference in roller radius. I think I will still use non-flanged bearings, though. They are much cheaper.
A final question. My side rails are rusty. I am thinking about shooting them with white appliance epoxy spray paint while I have it apart, but if the paint flakes off, which it will because the thing is sliding up and down it, it will be a big mess. I guess I will just live with the rust.
Science is what we understand well enough to explain to a computer. Art is everything else we do.
--A=B by Petkovšek et. al.
The side rails on my enlarger are aluminum. If yours are rusty they must be steel. If you have it apart you could wet sand them with very fine sandpaper or maybe use a fine wire brush. If you can find someone local who does sand blasting you might take it to them to have them cleaned up. I would not sand blast them but they might have a blasting medium more suitable for your needs. Don't paint them. You are correct: it will be a big mess.
You might coat it with Rust Chek rust converter, which will change the rust to a grey oxide and stop further rust(on the rusted area, it needs rust to work). If you are in a rust forming environment, new unrusted metal may rust and need to be treated. but I expect your enlarger will be in a nicer environment now.
See www.classic-enlargers.com. Harry Taylor has been the leading go-to guy on older Omega enlargers for quite a while now. (I use a D-II, and it will outlive me.)
My advice: if your enlarger used 3/4 rollers, don't try to change the size. They need to be about the same size to work.
You can't get 3/4 flanged bearings, only 7/8, and I was trying to save a buck anyway (the McMaster bearings are $10 each), so I bought 3/8x5/8 ball bearings for a dollar each on Amazon planning to make 3/4" flanged tires for them. They didn't work plain, because they were too small, but 7/8 wouldn't have worked either. I made non-flanged delrin tires for them on the lathe. That's why I have a $1200 lathe; so I can save $40 enlargers when I need to. The bearings are pressed on the shafts, and the loose ones I used loctite. There is no need for flanges IMO.
My head was bent pretty bad so that 4 rollers never contacted the rails, only 3, with at least 1/8 inch of rocking. This corresponds to the giant flat spot that was in one of the original rollers. I bent it back some, but ended up forcing it to lie on the rails with the idler rollers. This worked only because the bearings are so low-friction.
Science is what we understand well enough to explain to a computer. Art is everything else we do.
--A=B by Petkovšek et. al.
While I am covering the refurbishment of this enlarger, I should share my LED light solution. A Cree TruWhite 4-inch ceiling light drops right into the enlarger head with no tools or modification needed. You can easily just pick it out and put the lamphousing back on if you need grade 5 or feel like dealing with popping negatives for old times sake. The LED is about 10W and is 1 stop faster with MGIV than a 100W bulb. Response to Multigrade filters is good, but shifted by about 1 grade such that grade 3 on the LED is about like grade 2 on the incandescent. This is ok for most of my negatives, and also gives an effective 000 grade which might come in handy one day.
Science is what we understand well enough to explain to a computer. Art is everything else we do.
--A=B by Petkovšek et. al.
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