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  1. #21
    rmazzullo's Avatar
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    possible alternative?

    PE,

    Instead of the coating blade being made from a single piece of stainless steel, can the blade be assembled from pieces of stainless steel bolted together to create the desired configuration? It might make cleaning a pain if the joints aren't tight enough to prevent seepage between components (disassembly, cleaning, reassembly and realignment), but perhaps some sort of sealant that is compatible with the emulsion can be used.

    Another thought that comes to mind is (I haven't tested this, it's just a thought) how does SS respond to grinding / polishing techniques like those that are used for telescope mirror grinding?

    Thanks,

    Bob

  2. #22
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    Quote Originally Posted by Falkenberg View Post
    Have You tried ceramic materials or Plastics like Polysufon from BASF. They are chemical resistant and heat resistant.
    Ceramics and glasses cannot be drilled and tapped for addition of the adjustable end cap. If pegs or braces are used, you cannot attain the 0.001" precision.

  3. #23
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    Quote Originally Posted by rmazzullo View Post
    PE,

    Instead of the coating blade being made from a single piece of stainless steel, can the blade be assembled from pieces of stainless steel bolted together to create the desired configuration? It might make cleaning a pain if the joints aren't tight enough to prevent seepage between components (disassembly, cleaning, reassembly and realignment), but perhaps some sort of sealant that is compatible with the emulsion can be used.

    Another thought that comes to mind is (I haven't tested this, it's just a thought) how does SS respond to grinding / polishing techniques like those that are used for telescope mirror grinding?

    Thanks,

    Bob
    They tell me that the blade must be one piece. Assembling it is actually as costly or more so due to the jig needed, the drilling and tapping and / or the welding involved. And, they can't guarantee the accuracy any more than what I get now, just no twists and bends.

    The grinding and polishing goes well. All blades are mirror bright! It is the milling out of a 1/2" piece from the center to make a well for the emulsion that causes the problem, and no method will work yet as the temper on the SS bar causes it to warp and twist when the 1/2" piece is removed.

    BTW, this only happens on bars from 8" up. The 4x5 and 5x7 blades are just fine. The problems worsen as the length goes up.

    PE

  4. #24

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    A few thoughts come to mind:

    Sintered powdered metal, though probably not cost effective on small runs, though I'd imagine there's somebody doing short runs.

    Are any high density plastics a possibility? not having seen a coating blade, so I'm guessing blindly, but Delrin and the like can be machined like crazy, when properly annealed.

    Is the concept of a holder with a removable or attached blade totally undoable? it shoule be quite easy, for example, to get some .1" x 1" precision ground stainless bar, and with countersunk holes, fastened to a larger piece. If the area that it is attached to is ground true, then the bar should hold it's straightness.

  5. #25
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    I've tried plastic and wood and found them to be too light. A piece of paper often has a set, or begins to curl when being coated. It also resists the movement of the blade, so I have seen paper lift the light materials up, and the blade sometimes tips over during coating due to drag. These materials are usable, but you may have more defects. I did not pursued wood or plastic due to these types of problems. One person has made a plastic blade I understand.

    There are pictures posted in this forum and on the slide show showing the blades. They are basically a bar of stainless steel cut to yield a [ form. The [ < gap there is the well of the blade and with an 8x10 blade holds up to 50 ml to allow coatings of silver emulsion and even carbon pigment. The gap is capped by an adjustable end cap or doctor blade making a 2 part assembly [ | < where the cap is bolted to the body with 4 bolts while adjusting the opening to about 5 - 20 mils depending on what you wish to coat. In the above, the left carat < is used as a pointer and is not part of the device. All blades are overwidth to allow for edge defects.

    Sintering sounds interesting. No one here has mentioned it to me. Can you do it with Stainless??

    PE

  6. #26

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    From what little I've seen, you make a mold, powdered metal is put in and compacted, then heated to fuse it solid, I'm pretty sure I've seen ad from companies that do all metals, including stainless. I stopped getting alot of the industrial design magazines a year or two ago, as I never had time to read most of them (except for Nasa Tech Briefs) and am going strictly from memory. A quick google search should turn up more hits than imaginable, as many complex parts are made from sintered metal today.

    erie

  7. #27

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    Ron,
    I just had an off the wall idea, have you ever seen a printing press ink fountain? it has a flexible stainless blade with what amounts to grub screws with a tapered tip that press against the blade. something similar could be designed simply, and could be adjusted post manufacture, then a drop or two of sealant on each screw would ensure that it stays put. By putting the accuracy part in the final, assembly stage, the tolerance open up, as cost goes down, it shouldn't be terribly hard to get a blade adjusted within .001" by making a jig that uses a dial indicater mounted on a linear stage, the jig cost would be more expensive, up front, but by making it large enough for your largest blade, could be used for all sizes. Depends on how agreeable your machinist is, in an ideal situation a retired tool and die maker with a surface grinder, mill and lathe in the garage would be the ideal machinist.

    Alternately a thinner blade could be lapped to within far less than .001" tolerance, as long as you design the holder to allow access to the doctor edge in such a way as to allow lapping. The removable end plates could facilitate that easily.


    erie

  8. #28
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    I have blade bodies and end caps in several thicknesses and several designs. The thin ones bend with finger pressure at a length of 8" and longer than that they actually 'quiver' as you draw them across the sheet of film or paper. The present thickness of the end cap was determined by trial and error to be the thinnest that will not bend with finger pressure. However, a blade that thick caused coating defects and so the thicker the end cap, the more taper that must be put on it to keep the edge of the blade sharp. The larger blade end caps are therefore not plates with flat edges, but are plates with a precision chamfer to achieve the optimum width at the contact point with the emulsion.

    It comes down to this though, most tool and die works or machine shops don't even want to work on jobs that run much less than $20,000 or so. It takes me about 3 months to get blades done, as they are not high priority because a 20 blade order stretches my budget but is peanuts to them.

    I go to the plant and dodge cranes, fork lifts and trucks to just get in the door. They are rushing around like mad to meet orders that tally in the hundreds of thousands of dollars for the big ones. So, I get a few minutes of a guys time and that is it. And, the smaller the shop, the slower they seem to be or the less interested.

    PE

  9. #29

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    You need to find a retired, or semi-retired craftsman machinist that still has his equipment and is willing to work on odd projects, just for the love of quality work, and a reasonable amount of pay.

  10. #30
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    I have a better idea.

    As soon as this batch is sold, I'm publishing the plans so that you can get your own made however you want and out of whatever materials you wish.

    PE

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