AndreiC Posted July 11 Report Posted July 11 I bought a couple of months ago a replacement panel cover from Vantage Plastics for my 1970 M20E. It seems to be a good reproduction of the old panel, but it seems that in the production process they made the edges much deeper (they are about 1/2", instead of about 1/8-1/4"). This issue also happens around each of the instruments. My question is -- what tool should I use to grind these edges uniformly all around? I don't want to end up with one side taller than another. Would a belt sander work? Also, what would you use to cut out openings in the areas where one would like an opening? (Like where the switches are.) Here is a picture of the underside of the panel. Thanks. Quote
MikeOH Posted July 11 Report Posted July 11 UGH! Have you tried calling Vantage Plastics and asking what they recommend? I think using a belt sander is going to be an exercise in frustration and bad results. The only approach I can think of, hopefully others will have better ideas, is to mount to a stiff plywood backing (1/2" or more) and then use an end mill in a vertical mill; that will ensure all the protrusions are equal height. Quote
Hank Posted July 11 Report Posted July 11 Be very careful using a belt sander on that plastic part! I would use a sharp knife or a Dremel tool to cut off most of what you don't want, and hand sand to get them all the same--glue sandpaper to a piece of wood. Fairly fine, like 180 or 220, will remove little bits of plastic quickly. Use a strip of sandpaper about 4-5" wide and full length, and attach to a flat board with spray adhesive. Cut new holes gently with a rotary tool like a Dremel. You may want to start them with a drill, and use the Dremel to make the hole larger. Good luck, go slowly and be careful! Quote
Flyler Posted July 11 Report Posted July 11 If you have wood working equipment, you could make a sled so that your saw blade only takes off .050" at a time or so. I have a radial arm saw in my shop and could see it working pretty well for this. Park the blade, hang it so it takes just a smidge off per pass, so it doesn't crack the plastic. Just slide the plastic past the blade by hand. I see MikeOH is also a mill guy (hiya buddy ) which is always my tool of choice... but not so common in home garages. 2 Quote
47U Posted July 11 Report Posted July 11 1 hour ago, AndreiC said: My question is -- what tool should I use to grind these edges uniformly all around? I don't want to end up with one side taller than another. Also, what would you use to cut out openings in the areas where one would like an opening? (Like where the switches are.) I trimmed a new VPP overlay for my right-side panel. I don’t remember trimming any of the instrument holes, but I did reduce the height of the outside perimeter. I think I used my heavy-duty scissors (or sheet metal shears?) to trim the excess. I also did some filing/sanding. Dremel? Try wrapping the cutout with some blue painter’s tape, cut the excess tape off with a razor blade. Then draw a line where you want the remove the excess plastic and snip away. A nibbler might have better reach than a shears/scissors into areas where the cutouts are close together. I used a step drill to make the holes for the mount studs and various circuit breaker locations. That was 15 years ago, so I probably need to update it again after the most recent round of avionics upgrades. But, still an improvement from where I started. Quote
N201MKTurbo Posted July 11 Report Posted July 11 I use a Dremel rotary file for the course work, then a sanding drum for the finer trimming. Swiss pattern files for the final finish. Doing it right takes a long time. There are no easy ways to do it. Just remember you can take off material, but you cannot put it back on. Your last cut can ruin all your work. Have fun and don’t rush. 1 1 Quote
DCarlton Posted July 12 Report Posted July 12 I agree. It takes a lot of time to make it look nice but you can do it. I used a combination of tools. A belt sander clamped to a workbench. Dremel tools (little sanding drums). Hole saws. Tapered plastic cups the size of the instrument holes wrapped with sand paper. I’ll try to post a pic or two soon. Quote
Aerodon Posted July 12 Report Posted July 12 I just did this 172 with a belt sander / rotary disk sander. there were some residual lines on the inside that I could use as a 'final' target, but just sand / check / sand until you are done. I also managed to use the front drum of the sanding belt to grind away the perimeter of the hobbs rectangle. The round holes were good from the factory. Aerodon 1 Quote
AndreiC Posted July 13 Author Report Posted July 13 How deep do you guys leave the round holes? The ones on VPP are about 1/2" deep, which I think is too deep, but I also don't want to mess up with them if I don't need to... Quote
Hank Posted July 13 Report Posted July 13 2 hours ago, AndreiC said: How deep do you guys leave the round holes? The ones on VPP are about 1/2" deep, which I think is too deep, but I also don't want to mess up with them if I don't need to... There is significant variation on my C. Up by the ASI is much less than over by the VORs. Not sure if it's a top-to-bottom thing, a left-to-right thing, or maybe some of both. Then there's the taper on the right-hand edge . . . I measured a random spot in the middle. Good luck with yours. I'd love a tracing so that I can plot out the center of the holes, as I struggle to make a replacement for mine, which is in three separate pieces. Quote
DCarlton Posted July 14 Report Posted July 14 On 7/13/2025 at 12:20 PM, AndreiC said: How deep do you guys leave the round holes? The ones on VPP are about 1/2" deep, which I think is too deep, but I also don't want to mess up with them if I don't need to... I reduced the thickness of the entire panel. Can't tell you how much. Season to taste. Some of the round holes I cut the flange completely off to fit around existing instrument light bezels. I used a larger hole saw with a wooden puck as a guide that fit the existing hole to keep the hole saw centered. Here's a couple of pics. Each hole tailored as required. Need to make sure you have plenty of clearance where needed. I went a little oversized on some instruments like the AI, DG and clock to make sure there's plenty of clearance around the buttons, knobs and shafts. If I were doing it again, I’d reduce the thickness even more. You can see the gap around the clock in the angled photo. 1 Quote
Pinecone Posted July 14 Report Posted July 14 I would make a form. Cut a circle of ply wood slightly smaller than the hole. Mount this to a larger piece of wood. Sand/file the smaller piece to the proper thickness. You would put this into a hole from the front, then use a Dremel drum sander to make the flange the height of the form. 2 Quote
Yetti Posted July 18 Report Posted July 18 Belt sanders mess up things very quickly. I would probably get a piece of oak the correct height that you could side around inside the circle. Then clamp a Utility knife blade to it to cut the plastic at a right angle. Or using the same concept of making a jig to slide around inside the hole. clamp a dremel tool to the jig with rotary bit to it like a mini vertical mill. A little less stable, but more adjustable cut half out base here and use it. https://www.lowes.com/pd/Dremel-1-8-in-Rotary-Tool-Cutting-Kit/1092895?store=3032&cm_mmc=shp-_-c-_-prd-_-tol-_-ggl-_-PMAX_TOL_000_Priority_Item-_-1092895-_-local-_-0-_-0&gclsrc=aw.ds&gad_source=1&gad_campaignid=21218097027&gclid=CjwKCAjw4efDBhATEiwAaDBpbhhPaHqzemAf2pNh60gIR6vXDZ8LIEwiLWREJ87F4hXik5Z8x1BEkxoCjIYQAvD_BwE lots of chips will fly, but should get good consistent level cut. Quote
Paul Thomas Posted July 18 Report Posted July 18 My favorite attachment for delicate work is the flex shaft. You can be so precise. https://www.lowes.com/pd/Dremel-36-in-Rotary-Tool-Flex-Shaft/5005469899 Quote
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.