170 Plastic Repairs

Discussion in 'Day Sailers' started by Shorefun, Oct 8, 2018. Add this thread to a FAQ

  1. Shorefun


    Joined Sep 5, 2018
    156 posts, 19 likes
    Hunter 170
    US Northfield, NJ
    I went through three 50mL MA300 glue packages today. I bought a more expensive metal dispenser ($25) and I am sure it was a good choice.

    So I did my grooves with a Foredom flex shaft tool. Way more comfortable then trying to use the Dremel. I have done quite a bit of work in the past with the Dremel but I picked up the Foredom tool very cheap at a garage sale. It has more power at lower RPM. It is better to run lower RPM as you do not generate as much heat and it cuts faster. Yes I tried the Dremel tool also to see which one was best. Hands down the Foredom tool. More control on where you cut, no heat on your hands, and way more power.

    I have included some picts of the glued parts. This is the first step and I am not finished. I still have some more at the rear to do a first fill and I will add some to the other joints as a filler. I will also cut down a couple of the longer lines and add in a layer of glass.

    As expected the MA300 had a solvent action on the plastic. After I layed my initial line of glue I worked it into the crack with a small spreader. The thickness of the glue caused it to pull at the surface and that is why it is concave when done. I do not know how much is also caused by shrinkage. I expected this from some of the body work I have done in the restoration of my 1931 Model A Ford Cabriolet.

    I found the slightly larger then 1/8" holes I used as crack stop were a good fit for the tip of the glue. I drilled a few extra holes where I knew I had a slight plastic separation near the crack. I pumped some in the hole. I did not do much as you have to be careful with the heat generated. I found those areas got pretty hot.

    The screw holes were kept open by screwing in the screw and shortly after applying the glue I removed the screw and cleaned them. I used denatured alcohol for cleaning.

    I used blue painters tape to limit my sanding. I masked off close to the edge on most the places. Before the glue set hard I pulled the tape off.

    Next, wait for more glue to show up. I also need to make up some flat boards for gluing down the floor areas that have pulled loose from the foam. I will be following Dave's recommendations and using the gorilla glue.

    In picture PA080273 that is one of the longer ones that is likely to get glass. That one was odd. Up over the side the crack had a bit of separation. Down on the floor where the crack ended it was overlapped slightly. So the shift in the structure pulled it together down there. Of course, the shape is very complex through there so there would be a lot of forces.

    Attached Files:

    JimInPB and H216sailor like this.
  2. Crazy Dave Condon

    Crazy Dave Condon

    Joined Jun 8, 2004
    7,258 posts, 786 likes
    -na -NA
    US Anywhere USA
    Although I would have done a few things different I welcome new approaches and ask that you report your findings so all of us can learn. Thanks and by the way you are detailed which is good

  3. Shorefun


    Joined Sep 5, 2018
    156 posts, 19 likes
    Hunter 170
    US Northfield, NJ
    A minor update.
    I got more epoxy and finished the few cracks left when I ran out of epoxy. Then I went back and worked on using what was left to fill in the lower areas. Temps in my area (southern NJ) were still well above 60 for a day or two so I really wanted to get the epoxy down while warm enough.
    Ran into an issue with filling the low spots. I was not using much glue per area. So I would place some glue then set the gun down. Well the glue in the mixing tip started setting up as I was not moving enough at a time. I knew that could happen and it did as expected. No problem I bought more.

    To be honest they sell the epoxy with a mixing tip. It is possible that you might not need extra tips if you have the work planned out properly. I needed the extra tips when I was trying to be a bit fancy with my work.

    Found that the cheap Harbor Freight (HF) sandpaper worked fine for the initial cut. I am using a vibrating tool with a hook and loop sanding pad to do the initial cut to level. HF does not have 220 for the vib tool, but the hook and loop round disks have the same hook and loop and will stick. So I used the sanding head as a pattern and cut the round disk to shape quickly with a box cutter.

    After my initial cut I am going to do a leveling fill. I got some Evercoat formula 27 at the local West Marine. Normally it is $27, but someone on Amazon was selling it for $13 free shipping and WM price matched right off my phones screen. My local ACE hardware had some 3M 5200 for $19 and WM sells it for $22 so I price matched that also. I finish level with 220 on a stiff foam sanding block (I have a kit for car stuff). I will probably jump to 400 wet. From there I am not sure. I might do some plastic polish then spray paint with the Fusion paint. No rush.

    I also need to figure out the floor stuff. I have a few ideas floating around in my head. No sure when I will have time. I have to watch temps for doing some of the work.