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Cutting resin and fixing a warped shell

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  • Cutting resin and fixing a warped shell

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    Last edited by UglyBagofWater; April 6, 2021, 10:14 AM.

  • #2
    UBoW, depends on the resin. Some will take to hot water treatment, some will do better with a blow dryer. I think, and someone else will surely chime in, that it depends on the casting and resin used. As for trimming, good old Dremel works or a new sharp Exacto. And then lightly sand to finish.
    Scott.....War Eagle River......Tampa, Florida, USA


    • #3
      Pour boiling water in a cup or jug, let it sit for 10 seconds so it's cooled slightly, dip the body in for about 3-5 seconds, it'll be pliable enough to straighten, let it cool whilst sitting on a flat surface.

      ...grinding is going to be messy! all resin is messy to grind whether it's poured or 3D printed, best done outdoors
      Kevan - Isle of Man
      Life is like a box of Slot cars...🚓🚗🚚🚜


      • #4
        Concur with WER on dealing with warpage. The thickness of the cast will be a factor in your success.

        I've been using a hot knife lately for trimming.

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        It slices through resin nicely and doesn't leave as much build up like styrene. No flying resin particles as well.



        • Kevan
          Kevan commented
          Editing a comment
          Good idea bud.

      • #5
        Another vote for hot knife, especially if the windows have some thickness to them.
        Come Race at The Trace!
        Timberline Trace International Raceway - SW of Mpls, MN


        • #6
          I've tried the hot knife, but it didn't seem to be hot enough. Maybe it's a cheap one. Hot water usually is all you need to soften any of the resins I've used. Grinding with a Dremel or using a hobby belt sander is the easy way to shape up a body. Be sure to wear a mask, resin is bad for your lungs. I also have one of those pedestal fans that I can set next to the sander or grinder to blow dust away from me. Outside is sure the best place for this stuff.
          Matt B
          So. In


          • #7
            Since resin by nature wants to remain the shape of the original casting, hot water may reset it if it deformed while sitting in a hot shipping box, etc.

            Thickness has a lot to do with it as well and these slush molded casts are hit or miss, even if poured at the same time by the same dude. Once the everything is trimmed, you should be able to get it back into original shape.

            All that said, it depends on the master which may have been warped, and the resin itself and how it was mixed. From the first photo, looks like you got this from the same place on eBay as I did ($10 right?). If so, it's not the best resin, but appears to be properly mixed although theres no evidence of vacuuming or mold prep in mine. But they're really cheap, so it's expected.

            All that said, when you do cut, sand, grind, use protection. While cured resin is inert and not the toxic horror show people sometimes make it out to be (it's the isocyanates in one part that is, very, very bad to inhale), the particles are easily lodged in your lungs since they tend to be sharp edged, just like silica. So wear a good mask and clean up the dust carefully and if possible, wet sand it.


            • #8
              I have a few of those resin bodies. Hot tap water was enough heat to sort the warp on the bodies I have. Take care cutting (especially the wheel areas) 'cause they can split if cutting with nippers only and cause some damage. I now cut those with a fine saw, small cutters, and shave with a knife.
              Last edited by code; April 10, 2021, 09:33 AM.


              • #9
                A Dremel with one of those 1/2 inch round sanding drums is the easiest way I've found to cut open a wheel well. Do be sure to ear a mask and if possible do it outdoors so the dust and mess is not in the house.

                Trying to cut resin with any kind of scissors usually does crack the body.

                I've not had any resin that ever changed shape after used the hot water treatment to twist or straighten it.
                Matt B
                So. In


                • #10
                  Here is the Firebird that I did years ago, an X-acto knife was all that was needed to trim the window and wheel openings. The body did have a slight warp and I fixed that with warm water. Recently I used a blow dryer on its low setting on an HO body.


                  • #11
                    Rich that looks good for an HO body. One of the best I've seen.
                    Matt B
                    So. In


                    • #12
                      I do all my sanding and dusty stuff like tire truing in my typical Asian made portable benchtop spray booth. You can just use it with the filter and it works but better to duct it out for painting.