Insetting 3-D Printed Patterns into a Match Plate. (Avoids fillet problems)

Discussion in 'Furnaces and their construction' started by Melterskelter, Jan 4, 2023.

  1. Melterskelter

    Melterskelter Gold Banner Member

    I have been printing patterns for a few months now. And, in some cases, using them on match plates. One annoying factor associated with putting them ON match plates has been having to make a fillet where the piece glues onto the plate. I have used various methods which have made the job easier but still not fool- proof. It finally dawned on me to print the part on a base plate that could be inset into the board. Of course, there still is a seam to deal with, but it is a seam on the flat surface of the plate rather than a very fussy inside corner. And that makes all the difference. That inside corner is now printed into the part with a generous radius perfectly formed by the printer.

    So, last night I printed a sprue and riser on 1/8" (arbitrary) thick base plates to be attached to the match plate for my angle plate. I have a good sharp 3/4" end mill that I will use to let the base plates into the pattern board. The base plates have 3/8" corner radiuses to allow a snug fit in the mortises I'll cut in the match plate board. Unlike the inside corner seam, the resulting flat seam need not be finished perfectly to avoid sand break out.

    Here are a couple pics:

    In progress. For scale, the pieces are each about 3 inches high. Spruew and riser in progress.JPG
    Finished. There are screw holes in the bases for fixing them in place. They will be coated with XTC-3D epoxy to make them slick. (The squarish base on the sprue accomodates a ceramic filter 2x2")
    Spruew and riser on the build plate..JPG

    From now on all my pattern pieces will be printed on such a base plate.

    Denis
     
    Tobho Mott likes this.
  2. Rocketman

    Rocketman Silver Banner Member

    Excellent technique, I will have to keep that one in mind.
    Makes it a bit harder to proof patterns before investing in building the matchplate, I suppose that could be worked around though
    Thank you for sharing!

    How well does the XTC-3D work? I've heard a lot about it but never used it. The last printed project I had I used the diluted bondo spot putty with great success.
     
  3. Melterskelter

    Melterskelter Gold Banner Member

    I don't have enough experience to be able to set up gating and risers correctly from the get go. So, I did initially just make the matchplate with its attached part patterns but no attached gate, sprue, or riser patterns. I then cast the part using loose sprue, riser, and gate patterns that have no baseplate. (I have accumulated an assortment.) Those loose pattern pieces don't require a fillet as they are drawn from the sand separately.

    Once satisfied that they were working, the next step is semi-permanent attachment of let-in base-plated patterns. And if they prove to be OK, they can be glued in and faired as needed. Partially or completely filling in a mortise that proves to be in the wrong location is pretty easy. If I did not have an existing loose pattern that I felt I needed for a particular piece, I would not hesitate to first print it to be used as a loose piece and then reprint it with a base plate. That duplication of work sort of goes against the grain. But so doing can save hours of work.

    I like using the XTC. It seems to have the correct viscosity for the purpose and I like the fact that it cures rapidly. I accelerate that cure rate using an infra-red space heater or using a seed germination warming pad. Getting the XTC-painted part up around 100F allows it to cure pretty hard in maybe a quarter hour to a half hour. I mix it in small quantities using and reusing 10cc syringes to measure accurately a couple cc batches. On a PLA part printed with a .4mm nozzle, one coat does a nearly perfect job of smoothing print lines and 2 coats will do it for sure.

    I think you wrote up the Bondo method you use, but I would not mind reviewing it. Could you link to a description of your method?

    Denis
     
    Last edited: Jan 5, 2023
  4. Rocketman

    Rocketman Silver Banner Member

  5. Melterskelter

    Melterskelter Gold Banner Member

    Thanks for the link, Rocketman. Good stuff.

    Here are a couple vids of a part pre and post XTC. I printed this part in PLA with a .4mm nozzle and .2mm layer height.

    I would liken the side pre-coat surface to something like that of a 33RPM record and I scratched it with my thumbnail to demonstrate that as visual interpretation via phone video is tricky. The surface is coarsest in the depressed upper center.

    And then 1 hour later I made the coated vid. There was no sanding prior ot application or after application of the XTC. I did force-cure it using an infrared heater.

    These vids are "shorts" so I can not use the usual video embed method.
    Pre: https://www.youtube.com/shorts/n7tiznpBJ6o

    Post: https://www.youtube.com/shorts/w1l3YDG8AMI

    Force curing the XTC on "low" setting. The parts are comfortably warm to touch---maybe 110F or so. Forcing XTC.JPG

    I am sure applesauce cans could be substituted for the pineapple cans. :cool:

    Denis
     

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