Methods for casting (or building) matchplates

Discussion in 'Pattern making' started by Tobho Mott, Nov 16, 2022.

  1. Tobho Mott

    Tobho Mott Gold Banner Member

    We've probably all seen Mr. Pete's classic series about casting an aluminum matchplate pattern. If not, it's here:
    https://youtube.com/playlist?list=PL6HIFled82YXGK9DfruOyOfT40gM9Xn9A
    (Specifically, the last 4 videos in this patternmaking playlist he's got)

    That method involves using steel spacers to elevate the cope off the drag before pouring; the gap between them fills up with metal to form the plate. But you have to be careful your spacer parts are perfectly placed not to leak, and if I recall correctly Mr. Pete actually packed extra sand into the gap between flask halves outside his spacers to dam it up in case his spacer segments did leak at the corners.

    Then there is OddDuck's method, he uses outer frame pieces as his spacer and the aluminum actually locks into the frame mechanically, making it become the outer part of the matchplate. I love this idea because you don't need to use a bigger flask than what the matchplate is meant to be molded in like you do with Mr. Pete's method. But we need a new post on OddDuck's method for this forum, I think it was only documented on alloyavenue. I haven't seen him post here in a while but his youtube is active. A video on his EZ matchplate casting system would be a great help to some, I'm sure.

    A couple of years ago I came up with an idea of my own. It's a variation on Mr. Pete's method, but I use a scrap of drywall with a matchplate-shaped hole cut in it as my spacer. Drywall survives molten Al ok, and doesn't tend to leak at the corners requiring external sand damming. It does need to be cast inside a bigger flask than it gets used with, but the ones I've made still fit inside a 12x12 flask which is easily manageable.

    I have posted about my method before in the project thread for the castings I used it for, but I'm afraid that the info will get lost there and not be so easy to search up if anyone is looking for some kind of a how-to. There was video too but the matchplate casting there is also buried in a 40+ minute video about casting carousel horse stirrup strap holders, not where you'd expect a matchplate casting how-to.

    Here's that thread fwiw: http://forums.thehomefoundry.org/index.php?threads/carousel-horse-stirrup-parts.1253/

    So anyhow, now casting matchplates has a dedicated thread that people might actually be able to find on purpose easier. I just cast another one (this time for parts I might actually need to cast more than one of!) and cobbled together a new dedicated video specifically on this topic as well:


    Anyone else got any cool tricks up their sleeve for casting a metal matchplate? I'm thinking about making some wooden plates too so I can use all the tips and tricks you guys have to offer as far as getting split patterns perfectly aligned when mounting them on a matchplate. What if I need holes too far from the sides for my drill press to reach?

    Jeff
     
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  2. rocco

    rocco Silver

    It's been quite a while since I last built one but for a wooden match plate, I make a wooden pattern pretty much the same way I would for a loose pattern with holes for alignment pins on the two halves of the pattern, being extra careful to make sure the holes are perpendicular to the parting line, on one half of the pattern, the holes go all the way through and I use that half as a drill guide to create matching holes on the plate then install pins a little longer than the plate is thick so that the pins can engage the pattern halves on both sides of the plate and after the pattern halves are fixed to the plate, use a little bondo to fill the exposed holes on the pattern half that was used as the drill guide
     
    Last edited: Nov 16, 2022
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  3. Tops

    Tops Silver

    On my only wooden match plate, I used former loose patterns. Each pattern half had 4 holes, 2 for alignment pins and 2 for extraction screws. I used CAD to calculate the hole locations after I grew the patterns for 1.5% shrink and the CNC drill to make matching holes in the plywood match plate. Then I ran dowels through the plate to catch the holes in the patterns. A set of transfer punches would have done the same thing, I just would have needed to drill through the patterns on one side since I printed them with blind holes. The transfer punches would have also been useful lining up the blank match plate to the flask. Sounds like I need to go to Harbor Freight... :)

    PS pic added
    matchplatev12_mod v2.jpg
     
    Last edited: Nov 16, 2022
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  4. Chazza

    Chazza Silver

    I do the same as Rocco; the method works very well.

    On my latest plate, I need to remove the patterns to fill the voids in the mould, so I used 1/8" welding rod as dowels.
     
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  5. HT1

    HT1 Silver

    This is the old school way it is done, one big issue for the hobbyist, is the holes have to be straight and true or your finished castings will be mismatched, so check that drill press real carefully .

    Kudos to Tops for including all gating on his matchplate, so many people skip/forget this obvious time saver

    V/r HT1
     
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  6. rocco

    rocco Silver

    That's why I mentioned being extra careful to make sure the holes are perpendicular to the parting line. When I made my first matchplate, I didn't yet have a drill press and was keenly aware that registration errors were a distinct possibility so after drilling the holes, I temporary fastened the pattern halves to the plate and carefully measured from the edge of the plate to the pattern on both sides in multiple spots to confirm that I had things right before permanently securing the pattern halves to the plate. Fortunately, I got a little lucky and got it right the first time but my plan B had there been registration errors was to enlarge the holes slightly to create a little wiggle room, then make adjustments to the patterns until the measurements from one side of the plate matched the ones from the opposite side.
     
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  7. Tops

    Tops Silver

    Thanks HT1 .

    Gating improved on above pattern here: https://forums.thehomefoundry.org/index.php?threads/one-of-those-nights.2405/page-2#post-48229

    If the pattern pieces have nice (tight) fitting pins and through holes, the match plate could be transfer punched and drilled from one side and just a hair over like 1/32" (.8mm) the pin diameter. Get one side's pattern(s) attached with short pins to register to those drilled holes and then replace the pins with longer ones (add thickness of match plate) and then pin the second side pattern to the pins coming from the first side.

    On the one above I would have been better off with 3 pins per pattern with one being out more toward the blade end and letting the holes go all the way through and filling them in afterwards, more like the lower green one below:

    tops_match_pin1.jpg
     
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