Update on coating blades
To those interested parties;
I have had a series of blades made up to 16" coating width. They were either milled or cut by water jet. The cutting method makes little difference in price or quality except: 1. Water jet cuts off center from end to end slightly due to the need to cut while holding one end and this needs some extra milling. 2: Water jet leaves an unmilled rough surface that requires further polishing.
Those are inconsequential. The final problem is this. No matter how the 1" square bars are cut, they bend after cutting due to the stresses placed on them during forging. This bend can be corrected, but leads to a lot of rejects and thus the price. This is a result of using high quality stainless steel to prevent interaction with the emulsions and chemicals. Aluminum would be much easier to work with but would ruin most photographic chemicals, even those of most alternative processes.
The bottom line is this. The largest blade I can currently have made is about 11" coating width. Larger than that, and the defects are just beyond being correctable. I have one 16 x 20 blade that is just marginally acceptable.
So, with the help of a friend, I am looking for other places and methods to have them made. In the mean-time, the prices will have to stay pretty much where they are to cover my expenses.
Thanks for the update. Your prices are already pretty much on a par with the only other coating blades widely available, those used for testing paint.
Still out of my range though :(
Have you considered laser cutting?
Originally Posted by Photo Engineer
It was used quite extensively at my previous place of work.
I think you would probably be looking at a multi-pass operation on high grade Stainless of the thickness you are dealing with, but even so, I think it would be possible.
There is another alternative, as sometimes used by moulding tool makers, which involves bolting flat sections together with precision dowels for alignment.
I think that if done properly, this could also work quite well.
Have you ever considered a "budget option" of a milled plastic body with a stainless doctor blade? - particularly in the smaller sizes.
Delrin would probably work reasonably well, as it machines and finishes well, and is dimentionally stable.
I think if you could produce a cheaper option like this, emulsion coating would come within the range of more people.
I've looked at all of the above. I've even priced out welding them in 3 pieces, but the stainless welding and grinding and polishing was very expensive. Drilling for dowels was expensive. Laser cutting of 1" metal required such high power and so many passes that the price was out of sight.
Plastic blades don't weigh enough.
At Kodak, they were either stainless or teflon coated low grade steel or iron.
Ah. You seem to have thought of everything!
Good luck on finding a solution, anyway.
I'll be very interested to see what you come up with.
How about precision cut hollow plastic, filled with approximately-cut steel for weight? Much like what was used at Kodak?
Originally Posted by Photo Engineer
Now that is one I didn't think of. I'll have to look into it. It may be that the labor is prohibitive, but you never know.
How about machining them from aluminum and coating with ceramic...I know that they do this with journal throws on large engine crankshafts and they have tolerances more precise than what you need.
I have not found anywhere to do that around here. I'll have to search further. Again, IDK what the cost would be.
The logical question, since you worked for Kodak..is..who made them for Kodak? Did they do this in-house? The machinist/vendor for Kodak would be the starting point, wouldn't it?
Actually, they were made in the Research Labs metal shop, in the basement of B-59 at Kodak Park. They cranked them out in batches in about a half dozen different styles for film and paper coating. They also made a coating block with vacuum, heat and chill capability, and special drying cabinets for the hand coated sheets.
Originally Posted by PHOTOTONE
They were not adjustable as mine are, but rather were welded or milled at precut values and then engraved with the value. They came in sets at 2, 4, 5, 6, 7, 8 and 10 mil undercut. In the recent cutbacks they destroyed most all of them and were unwilling to loan, give or sell any to anyone. I did contact several friends in current management regarding this, and was turned down. In fact, I was refused any sort of help in any fashion by Kodak in my current emulsion projects.
A number of the people in the shop knew how to make them, but are now all retired. I doubt if a set has been made for over 20 years. Just about every individual who did hand coatings had several sets in different styles. In any case, I see little advantage from this even if I could find one, as they didn't care how much it cost, they just went ahead and made them. So, Kodak's blades probably cost a lot more than mine for all I know.
If I wanted to.... The former head of Facilities and Engineering at Research lives across the street from me. IIRC, he ran the metal shop. I never even bothered to discuss it with him due to the above lack of interest at Kodak and my feeling about their costs.