Adventures in Acrylic

jules

#1

I’m almost feeling kind of guilty about posting things now…holler when you’ve had enough. :wink:

I’d done a little bit of work with some extruded mirrored acrylic earlier last month and although the project turned out okay - the smell of the acrylic after the print was enough to put me off of it for a while.

So I finally tried out some of the cast Proofgrade acrylic. And I know everyone thinks I’m totally in the tank for Glowforge…and they would be totally correct…BUT that’s only because they’ve earned it. The Proofgrade had the mildest “scent” of any I’ve tried, including the EBay purchase, the Instructables freebie, and the local HW store variety.

And it didn’t hang around afterwards like the other ones did.

The Proofgrade is just beautifully clear, thick, and it cuts like a dream. (No flashback either now, which was excellent!)

Okay…so one of the things I designed a while back was what I called a Slump Bowl, but actually was a Hump Bowl (check out the Free Files section for the file and the story…it’s a hoot), so I wanted to cut that bowl to see if it worked (it does) and take a shot at actually getting it to deform.

Okay, the second part of that, the deformation part, I haven’t gotten to finish up yet - I tried slumping one with a variable speed heat gun, and only got a slight deformation out of it after about half an hour of holding that thing. (I had the heat set too low, 400°F. I’m going to crank it up a few notches for the next one, which i actually will turn into a bowl shape if I can.)

But I managed to deform the prototype just enough to make a slightly curved dish shape, and that led to another idea - so i ran with that instead…

Cupcake Stand.

(Pretend those apples are cupcakes…I didn’t need the temptation hanging around)

So anyway, the acrylic is beautiful, I just need to work on getting the slumping technique developed. That one is not quite even…

That cut also had a technical glitch (always triple check your files for hidden paths) :rolling_eyes: but it works well enough for a test case.

I also wanted to try a little engrave on the acrylic so I fluffed up a little bunny token to go with the wooden one.

That’s it for now. :relaxed:

Oh, and I sure hope Glowforge is planning to offer 1/16" acrylic too…hint, hint.
(I think it will drape better.)


Weekly Highlights for the Week Ending April 15th, 2017
Proofgrade Acrylic Slump Bowls
#2

Real nice work! I hope you put that cupcake tray in the catalog. I’d buy one!
Oh and… I like your bunny.


#3

One thought I’ve had for making slump bowls is to laser-cut a multi-layer form to slump it over, so it’ll be symmetrical and even.

Also, did you try putting it in the oven rather than using a heat gun? I found a document from Plexiglas that talks about methods for forming acrylic, it seems the target temps for forming (judging from table 1) are about 340-350 degrees F.


#4

Love the tray…with a wider base I bet it would hold a cake too…hmmm may have to make some of those…


#5

Ohhhhhhhhh just pretty. I like the idea of using a form to help guide the bowl.

And a hair off topic but everytime you guys mention using heat to form stuff, this pops up in my mind:


#6

I need to decide if it’s worth it to potentially sacrifice one of the ovens to test it.
(Or buy a cheap used toaster oven dedicated to the purpose. Probably will do that.)

But yeah, I think I’d get better heating through the acrylic doing it that way…it just cools off too quickly with the heat gun.


#7

I’ve never tried it, does it smell or something? I would think as long as you watch it and don’t let it contact anything metal, it should be fine. Similar to heating up polystyrene for vacuum forming.


#8

Since the ovens can’t be replaced (no longer making that model) I just don’t want to take the chance. I’ll pick up a toaster oven off Ebay or something.

(Heck, we might even have one out in the garage…I think hubs picked it up as one of the door prizes on one of the many activities he gets to sponsor.)


#9

use the oven on with it ontop of a bowl ?

btw so pretty


#10

That might work…


#11

I find that a heat gun is hard to use to make a hump or slump bowl. It’s tough to get the whole thing warm enough - as soon as you get one section good to go another section has cooled.

What I did find worked was using my gas grill and a couple of ceramic bowls that can nest together. I heat up the grill as high as it can go (with the ceramic bowls inside). Then I put the acrylic inside - either on top of one overturned bowl or on one that’s right side up.

If I put it on an overturned one, then that bowl has to be the smaller of the two. Then I take the larger bowl and place it upside down on top of the acrylic - need to line it up carefully so it’s all centered. Then I close the grill. Give it a few minutes and check to see how it’s humping. The whole sheet of acrylic will warm and the larger bowl will start to push the acrylic down, sandwiching it between the two ceramic bowls.

If you want to slump, it’s the same way except the acrylic is placed over the upright larger bowl and the smaller ceramic bowl is used to weigh it down until it slumps into shape.

You can also do it with just one forming bowl and after it gets soft enough shape it over or into the shaping bowl by hand. The trick there is that the acrylic will be HOT so you need to work in fast little pushes with your hands (gloves will leave impressions on the acrylic).


#12

Yeah, that might work best…it’s got a really high dome on it…

(Guess it’s time to burn myself for my art…I think I’ll wait till the weekend.)

Do you think pyrex would work? I’ve got a few of those that nest.

:smile:


#13

Pyrex should be fine. It’s oven save to 500F IIRC.

I have a couple of ceramic ones I bought from the local big/job lots store. Figured my wife wouldn’t be upset with me making plastic “melt” on them :smile:


#14

How high can you go with ceramic? (Is it thick stoneware?)


#15

I don’t know. Good ceramic is up over 1000F but lord knows what the job lot store stuff was - it was cheap and made in China so no name brand or anything. Some no-name stoneware that was pretty thick looking so I figured worst case it’d crack and I’d grab the bowls from the kitchen :wink: I’d expect stainless steel bowls would work fine too. You’ll not get your gas grill too hot for oven safe pyrex. Just be careful - check it frequently until you get a sense for the timing because too long and the acrylic will develop bubbles :slight_smile:


#16

Last question - rough time estimate? 15 minutes? 20?

(Thanks for the directions!) :wink:


#17

5 :slight_smile:

It’ll depend on your grill and how long you let it heat and the outside temp which will cool it down when you open it. I have a Weber with 3 strips of burners front/middle/back. I start it with all of them on high until the thermometer pegs itself. Then I turn off the middle and turn the front & back burners to low.

Oh, btw, put it all on a cookie sheet or something. That way if you drop the hot acrylic or bump it or something it won’t get grodied out on the grill rack.


#18

Ceramics are fired starting at 1700 and up to 2300+. You’ll be safe slumping/humping acrylics. :slight_smile:


#19

Fantastic! Thanks for all the tips guys! Might give it a shot this weekend…got to scrounge for some bowls.

(What the heck, I’ve been looking for an excuse to switch styles on the Corian anyway.)


#20

I have to know, is there just one Ficus that moves around like the one Glowforge?