Cutting curves in acrylic?

[MikeDVB]

Hey guys!

I’m working on some piggy banks for my kids. Just cutting some pine out to be shapes and then putting acrylic on either side for a “window” into the banks.

I’ve tried using the band saw and I seem to have a very chippy edge. Any suggestions?

 

[rst]

I cut shapes in acrylic and other plastics regularly.  I use Bosch fine toothed Japanese style blades with a Bosch or Carvex jigsaw (depends on whether I'm in the shop, at home, or at a job site), set to speed #3.  The most important thing is to prevent technique is to prevent the plastic from fluttering.  If you experience the plastic wanting to fuse behind the cut, slow the speed.  In really tight curves, I sometimes move the blade backward after cutting forwards a small amount. 

 

[SteveW]

Have cut lots of acrylic in the past on a bandsaw without lots of chipping.  What blade are you using and how thick is the acrylic?  I haven't tried it but you can flame polish the edges of acrylic.

 

[Peter_C]

Router for cutting curves. Tracksaw with a plastic blade, or a table saw with a plastic blade. Even a jig saw can cut acrylic, with the right blade. Bandsaw with the right blade should do the trick too.

Turn the speed down and cut slowly.

 

[Cheese]

If you have a jig saw, Bosch makes blades specifically for acrylic materials.
https://www.boschtools.com/us/en/boschtools-ocs/t-shank-jig-saw-blades-for-plastic-t102bf-43080-p/

I know it's an extra step, but I've used blue painters tape on plastics and that improves the cut.

 

[MikeDVB]

I do have a bosch jigsaw with adjustable speed - I may even have some plastic blades [I bought a combo kit of blades at one point].

I don't mind taping the edge to make it cleaner - I'll give it a shot.

I'm not sure what blade I have on my band saw - it's been a while since I purchased it and my memory is terrible.  I know it's a very shallow blade and can do really tight turns but beyond that I don't remember the details .

 

[Peter_C]

Is this something you can use a pattern bit with a bearing, and a router? That will produce the cleanest cut period. Can you make an MDF or the like template, then cut it with the router?

If the edges aren't seen, the fastest way to cut it is the best. If it needs to be polished edges the router is the best.

 

[tomp]

I rounded the corners on this oversize base plate using the corner template shown and a bearing guided bit in a trim router - just nibble away to get close and then make a smooth final pass. On larger curves, use a jig saw with a plastic-cutting blade - use blue tape under the cut line, make a smooth cut just outside the line and sand to remove the saw marks. Never flame-smoothed the edges (sanding up to 400 grit was OK for what I was doing), but there are videos showing the technique on YouTube.

 

[MikeDVB]

The edges will be visible - as I am going to be drilling and screwing the acrylic to the sides of the project - but it's not imperative that they be perfect.

I just really don't want to spend a ton of time sanding the edges [sanding is one of my least favorite things to do] .

 

[MikeDVB]

To give you an idea - this is the type of thing I'm wanting to make - seems simple enough.

I hadn't planned on putting a plug in the bottom - but simply screwing the acrylic to the sides so you remove the screws to get the stuff out.

That said I could always make a plug for the bottom and secure it with a single screw...

 

[Koamolly]

Hole saw without guide bit drilled through a piece of ply as a guide clamped over plexiglass maybe?

 

[Michael Kellough]

Plenty of options for cutting curves above but if it’s circles you want I’d just buy them readymade.
https://www.usplastic.com/catalog/item.aspx?itemid=24593&catid=0&clickid=popcorn

 

[Cheese]

Great suggestion Michael. I purchased a bunch of those for some exterior lighting projects. They are available in different thicknesses with a blue protective film on both sides.

 

[rst]

There is another, rather expensive way.  My Shaper will cut excellent circles with no input needed, the internal software will cut any size circle or basic curve.  I have cut various circles including a 50" diameter from 1/4" acylic with a plastic routing bit.  I've cut curves in the past with all the above mentioned methods over the years.  When I've need an absolutely perfect fit for a project I've used a vacuum jig pattern to hold the piece and a trammel point jig to rotate on my Powermatic sander to creep up on the diameter.

 

[MikeDVB]

I wasn’t going to use circles - was going to try to be a bit more creative.

 

[Cheese]

I wasn’t going to use circles - was going to try to be a bit more creative.

Very cute idea by the way.  [big grin]  I’d focus more on the creation of different critters and just purchase the the acrylic discs. The kids will be more impressed with how big their zoo is as opposed to the form the acrylic window takes. Kids after all...are just kids, that’s the reason you love them.

 

[peter halle]

If you decide that you don't want to due the cuts yourself you could always look for someone who has a laser cutter.  Your size and desired thickness of material will dictate availability.

Peter