Turning plexiglass

[Dave Bureau]

I have to make 56, 3.25" disc out of 3/8 plexiglass. I dont want a center hole in it and I'm thinking the disc will get stuck in the hole saw if I use one. I thought I might mount them on the lathe on a vacuum chuck and part out the disc that way. I could just make a dimension mark on my tool rest and whip them out. should this work? I have never turned plastic? Any other thoughts?
Thanks

[Gary Max]

Plexi is hard and will want to tear out and chip.
You are going to have some work sanding and polishing the sides
Have you looked over at Fleabay for round stock?????

[Ken Fitzgerald]

Dave...I'd think it would work. Watch your speed. I have actually had problems when drilling or cutting plexiglass if the speed is too fast it will cause the plexiglass to melt.

[bob edwards]

I have not turned disks but have turned several finials and find that it turns very well. With a sharp gauge it remains crystal clear and requires little polishing. If I understand you correctly the vacuum chuck idea should work just use a sharp tool and lite cuts.

Bob Edwards
San Antonio

[Dave Bureau]

it doesnt have to be polished edges or anything. as a matter of fact they wont even be seen as they will be covered. just looking for the easiest way out. I'm only getting $900. for the job and dont want to make a marathon out of it.

[Steve Schlumpf]

Dave - if the edges don't matter - I would figure out a way to use a hole saw. Something that would be quick and easy. As long as the saw speed was fairly slow and you didn't apply much pressure - the hole saw concept would get my vote. Maybe lube the saw before each cut?

[Dave Bureau]

Im going to try a hole saw first. as this would be the easiest way. I'll try rhe lube idea and maybe drill some holes in the bottom of the holesaw so I can pust the discs out.

[Robert McGowen]

Im going to try a hole saw first...........and maybe drill some holes in the bottom of the holesaw so I can pust the discs out.


Not wanting to assume too much, but from your comments I am guessing that you have not used a hole saw before. All of them will have a way to push out the discs formed by the saw, either slots in the side, holes in the top, or more likely, both. You also can't just cut the discs without the center drill bit without taking some extra steps.

You can cut the discs without using the center drill bit, which of course will leave a hole in the middle, a couple of ways.

You could use a drill press, but the plexi will have to be firmly clamped down with no wiggle room at all. It will probably be a pain to do.

Having done something like this before, the other way that I would do it, is to take a scrap piece of 3/4" plywood. Drill your hole in it with the hole saw. Throw the middle away and keep the piece of wood with the hole in it. Use that as your guide. Clamp the wood with the hole onto the plexiglass. The easiest way is to just clamp it to a table with another piece of disposable wood under it, so that you have the table, a piece of scrap wood, the plexiglass, and the wood with the hole in it clamped together. Just use one pipe clamp to hold it all together on the edge of the table. The holesaw will be guided by the hole in the first piece of wood and will not wander around, even without the center drill bit. It will cut the plexiglass. Then just pop out the disc from the saw, loosen the clamp and slide the plexiglass forward, and do it again. Just my take on things. Good luck!

[Dave Bureau]

Not wanting to assume too much, but from your comments I am guessing that you have not used a hole saw before. All of them will have a way to push out the discs formed by the saw, either slots in the side, holes in the top, or more likely, both. You also can't just cut the discs without the center drill bit without taking some extra steps.

You can cut the discs without using the center drill bit, which of course will leave a hole in the middle, a couple of ways.

You could use a drill press, but the plexi will have to be firmly clamped down with no wiggle room at all. It will probably be a pain to do.

Having done something like this before, the other way that I would do it, is to take a scrap piece of 3/4" plywood. Drill your hole in it with the hole saw. Throw the middle away and keep the piece of wood with the hole in it. Use that as your guide. Clamp the wood with the hole onto the plexiglass. The easiest way is to just clamp it to a table with another piece of disposable wood under it, so that you have the table, a piece of scrap wood, the plexiglass, and the wood with the hole in it clamped together. Just use one pipe clamp to hold it all together on the edge of the table. The holesaw will be guided by the hole in the first piece of wood and will not wander around, even without the center drill bit. It will cut the plexiglass. Then just pop out the disc from the saw, loosen the clamp and slide the plexiglass forward, and do it again. Just my take on things. Good luck!

The saw I have only has holes in the side. i was worried about the plastic melting once inside and sticking to the saw. Holes in the bottom, I think would be better. As far as drilliing the holes without the center bit. that wont be a problem.

[Bernie Weishapl]

If your hole saw doesn't have holes of it do like I did. I drilled some holes on top because I only had the side slots on the one I bought. That way I could stick a hole punch in and push the piece out. Drill them on opposite sides if you only do two but I drilled four holes so I could evenly push the piece out.

[Leo Van Der Loo]

Hi Dave
If you have strips of plexiglass, cutting disks could be very easy and quick on a drill press.
First make a bottom block with a groove cut in it for the plexiglass strip to be able to slide through, like a shallow U.
Then make a top block with a hole drilled for the hole saw to fit in, this will keep the hole saw from wandering.
Now clamp the top and bottom blocks onto the drill-press and insert the plexiglass strip and drill, next, next,

[Leo Van Der Loo]

To eject the plug/disk, I think a thicker disk with a push spring fastened to the hole saw should be able to push the disk back out if the spring is strong enough and the thicker disk is just even or slightly outside the saw to start of with, a bit of wax on it should prevent scoring the plexiglass.

[Quinn McCarthy]

Dave

I would make a jig for my router. Just cut a whole in a piece of plywood the right size for the piece size plus collar and bit width X 2. You could cut multiple blanks at once with the right jig set up.

Hope that helps.

Quinn

[Jeff Nicol]

If you get a new carbide tipped hole saw it will cut like butter and not get to hot if you us the slowest speed on the drill press. The hole saw may cost a little up front but the time saved would be great! I think Leo's idea of cutting strips and make a jig that you slide them through would work well.

Jeff

[Harvey M. Taylor]

I was going to suggest the router, but someone beat me to it. No melting, just be carefulwith the last eighth or 16th. maybe stop and cut the last out with a saw or knife.Works for me. Max

[Thomas Canfield]

If you have a bandsaw, you could stack several pieces of plexiglass together with pieces of double stick tape to a wood base with center hole and cut using a circle cutting jig. That would give a reasonably smoothe edge and no center hole. You would need to check about the saw cut "melting closed" due to heat.

[Larry Marley]

I have made several round cutouts with a plunge router and circle jig.
use turners tape ( this is the turning forum) to hold the piece in place.
you can use the turners tape to attach a small block with the pivot pin to the center of the disk if you do not want a hole.
very repeatable. Used this to make my router table inserts, bandsaw throat plate...

can also use a template with a pattern bit, top bearing.