Dennis,
A couple of things.
1. Assuming that your saw is not modified, a stock saw blade spins much too fast for a great job in cutting any sort of plastic. The high blade speed, generates too much heat and the plastic melts, rather than cutting cleanly.
2. Also, it is likely that the saw kerf is too wide, such that too much material is being removed at one time - and thus too much heat is generated and thus the material melts rather than being sliced cleanly.
Since you have some pieces cut, but they are not square, the easiest thing to do, would be to simply sand the material with a 90 degree jig such that you end up with square ends on the material.
If you have access to a disk sander, you can easily square up the ends with no issue.
If not, and if you want the pieces cleaned up quickly, take the pieces to a machine shop and have the pieces machined square in a few seconds.
---------------------------
By the way, I had such issues with tennessee grip cork handles for fishing rods. i.e. I would make a handle of cork rings and make plug for the hole at the butt of the rod to create a finished end at the end of the rod to form a clean butt cap - so to speak - on the fishing rods.
I would use a disk sander, but I had trouble - insuring that the ends of the grip were square.
My solution was to use a cross lock vise. I had an extra disk sander that I normally used when working with various materials used in rod building as well as general shop work. But it was sitting idle, so I built a dedicated 90 degree sander to finish the ends of any rod grips that I built.
The picture of the sander with the cross vise as part of the machine:
[
www.rodbuilding.org]
Current version of the cross vice from Harbor freight:
[
www.harborfreight.com]
------------------------------------
So, for myself, I would use the disk sander with the cross vise to put a perfect 90 degree end on the pieces of material.
-----------------------------------
However, there is one more machine that I would use initially to make the cut. This is a mini chop saw that I use with a 3 inch very thin abrasive cut off wheel. In addition, I use a router speed control to reduce the speed of the cutting wheel to a speed that is just barely fast enough to cut the plastic material. The worst enemy of cutting plastic is heat, and heat is quickly generated by a fast turning blade. So, slow and steady wins the race every time for this material.
[
www.rodbuilding.org]
To create this mini chop saw, I started with the standard mini chop saw from Harbor freight. Then, I removed the saw from its base and used a disk sander to remove all of the raised lettering on the base of the saw that were numbers for angle cutting. Since I only wanted a 90 degree chop saw, I had no need for such lettering. Then, I used a piece of small aluminum to create a work backstop at 90 degrees to the blade which was screwed in place. Then, I removed the 2 inch saw blade and replaced it with a very thin 3 inch abrasive cut off wheel. Finally, I connected a router speed control in between the ac outlet and the 120 volt ac/dc universal motor that was the motor in the saw. This motor is virtually identical to the typical ac/dc universal motor used in sewing machines or most of todays power wrappers. This control allowed me to dial in the slowest speed that would just barely cut the material, but by turning more slowly, generated very little heat and thus did little melting while cutting the plastic material.
[
www.harborfreight.com]
[
www.harborfreight.com]
[
www.harborfreight.com]
--------------------------------------------------------------------
By the way, if you happen to have a vise, you can improvise a simple square cutting sander. Simply put the piece of material that you wish to clean up into the vise. I am assuming that the ends of the vise are at 90 degrees to the jaws of the vice. Then, gently close the vice just enough to secure the piece of material with the non square ends of the material protruding from the end of the vice. Then, simply take a piece of sand paper on a sanding block, and sand off all material that is protruding from the end of the vice and you will have a square end on the material. It would really help you if your vise happened to have a horizontal groove in the face of the vice jaws to insure that the piece of material was placed into the vice jaws squarely.
An inexpensive vice to use would be a drill press vice as shown here:
[
www.harborfreight.com]
One could lay a piece of appropriate sized material on the bed of the vise and then lay your piece of material that you need to square up and leave the non squared end of material protruding from the end of the vise. Gently close the jaws, so the work piece will be secure without crushing the piece. Then use a sanding block on the ends of the vice to square up the end of the piece of material that is protruding from the jaws of the vise.
Best wishes.
