I would assume that other emulsion makers, such as Ilford, Fuji, Efke, forte, etc., would also use coating blades for testing, and also it seems the paint industry, and possibly other non-photographic coating manufacturers would use this technology for testing coatings. Who makes this type of coating applicator for the paint industry?
Applicators like this for the paint industry have been described here and elsewhere. They are made of untreated aluminum for the most part, and run about $1200 for a 4" blade.
Oh, I won't ever be making a blade. I was just speculating, for general conversation and further knowledge. Sometimes ideas and thoughts put down into sentences and paragraphs can cause new directions in thinking. I was just trying to stimulate discussion about all the options possible.
Originally Posted by Photo Engineer
Try here: http://www.drblade.com/drblade.asp
This was the first place I called when I started my quest. His prices were out of sight.
How about this:
Use Ole's basic idea, but injection mould the blade body with bars and tapped inserts embedded, then machine down critical surfaces using the threaded inserts as datums?
I know this would incur toolmaking costs, but it might be worth it in the long run.
One material that might work is the epoxy resin used in switchgear mouldings.
Lens caps and cable releases can become invisible at will. :D
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I'm retired. I can't afford it! Sorry.
So, I have to make it one at a time or in small batches that a small shop can make. And I have to be able to afford making a prototype or two and then a batch of 10 or 20.
Well, after looking into several of the alternatives offered here, I have learned a lot more.
1. Plastic blades with weighted centers: Kodak used teflon on cheaper metals because that was the only plastic (it is really a polymer) that is not photoactive in some way or which does not absorb chemistry from the emulsion.
2. Wood blades with metal inserts and polymer coating: See above, apparently only teflon works.
In the final analysis, the teflon becomes scratched and the contamination or erosion process of the blade material begins.
It looks like titanium and stainless are the only metal options available. Welding or some sort of milling are the only ways of working with these metals.
That is a summary to date and my thanks to all for their comments. I'm still open to suggestions.
Either take a rough/bent blade and provide a way for the purchaser to hand-lap it back to true.... or make the blade out of glass.
Remember, the amateur telescope makers are polishing aspheric mirrors by hand with easily available tools.... and a lot of time.
Can you drill and tap glass? IDK.
I have only one bent blade. It was the 16" blade to show how bad the problem is. The shop has never given me any of the other bent failures.
What about a thick teflon blade bolted to a metal core? Teflon is kind of expensive, but if you could attach a thick sheet and then grind/cut/polish to your needs it might work.
Could you prototype with something cheap like HDPE? Or maybe Delrin?
You can get sheets of each of the above at http://www.usplastic.com/catalog/pro...uct%5Fid=10533
HDPE and Delrin and a bunch of other materials through the same place. You can get Titanium from http://www.smallparts.com
The idea would be to cover the face of the device with the sheet of teflon and leave say 1/2 inch on the trailing side so that you have less of a chance of getting the solution up on the metal parts. You might still be able to use Stainless for the metal, it just wouldn't need to be as exacting. If you used stainless for the body, you might be able to reduce the amount of teflon needed. That's all going to be dependant on the stiffness that you need.
In theory you could just use a straight bar of metal and let the plastic do all the work. The advantage would be that you could replace the blade if it was damaged.
All the same might go for a stainless body with Titanium scraper. Once again this would off a replacable blade for a lesser price than the whole unit.
I took a quick look around the web to see if I could uderstand the needs a little better, but there are few pictures of what you are making, so I only have a rough idea. Essentially it looks like this device is a scraper that is positioned at an exact level above the paper. A large amount of the solution is applied at the edge of the scraper, and the paper is pulled through to apply the coating evenly over the top of the paper. Speed of pull, thickness of solution, and scraper height above paper determine the thickness of the coat (other factors may apply). The coating needs to be uniform within about 1/1000 inch to make sure that you get even tones when it is exposed to light. A thicker spot will give a higher concentration of silver, which will give a different tone than a thinner spot when the same amount of light hits them.
Is my theory correct? (in it's somewhat simplistic way)
If it is, then you may be able to makes the base metal structure in a modular way so that many different widths can be accomodated simply by switching the length of the plastic scraper (and careful setup of the scraper). Since you are using plastic for the scraper, you could put in adjustment screws in order to fine tune the edge all the way across the device. You could probably provide the same adjustments to the metal blade, but it would take more force to make the corrections.