Acrylic A Tad Too Big

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Shayla

Shayla

WOW Framer
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Joined
Apr 5, 2008
Posts
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Washington State
Got a piece of UV acrylic in last week, and although she tried
to cut our frame the correct size, I think it's a bit different from
back to front. So, although the acrylic measures right and the
frame back measures right, when I fit the acrylic down inside
the 2" shadowbox depth to the front, it's too tight.

I don't cut acrylic, and our glass shop can only trim it 1/4".
But even 1/8" would be almost too much. It's Tru-Vue and
still has the covers on both sides. Is there a way to make it
smaller by sanding it with something? I'm concerned about
too much heat building up and affecting the plastic. I know
we could also try cutting some wood out, but that would
be difficult. Size is 39 x 60. Any ideas?
 
Shayla, I use an electric planer. I cut loads of plexi and from time to time, I run into that same issue.

The electric planer can remove anything from 1/32- 1/8 at a swipe. It's a convenient tool to have around. See if any neighbors have one. If not then a hand held electric sander or electric belt sander will do the job.

Just have the frame, plexi and cutting tool in the same area, so you can do trial fits after each pass.

It does make a dusty mess, so better to do it away from your fitting area.

Electric planer:
7698K_1.jpg
 
We use a small router-trimmer with a flush cutting bit. Same principal as the planer that Mark suggests, but I feel I have way more control and can also do other things with it - such as square up a piece of acrylic by taking a fraction off at the start of the cut and more towards the end.

We clamp a straight edge on the acrylic and the bearing of the router bit rides along the straight edge. Easy to trim off as little as 1/6" in a single pass and you can see what you are doing. The acrylic sheet sits flat and the tool rides on top. I think it is much easier than the planer - and certainly more accurate and cleaner than sanding.

 
Acrylic can easily be sanded - dry or wet. I have made sandwich frames from time to time and I have wet sanded the edges 220, then 600, then 1200 and finally buffed it for a nice polished edge. .

If you had a plastic cutting blade for a circular saw you could trim the edges using a straight edge. or if you had a table saw set up with a plastic cutting blade you could trim as little as a 1/64" or less.

The other methods suggested work as well. Being thin, acrylic will vibrate when being cut, routed, trimmed, sanded, etc by electric tools so it is important that it has support so it doesn't vibrate as it can crack.
 
Larry Peterson said:
If you had a plastic cutting blade for a circular saw you could trim the edges using a straight edge. or if you had a table saw set up with a plastic cutting blade you could trim as little as a 1/64" or less.
Click to expand...

An excellent suggestion - but impractical for many smaller shops. I have a big shop - but the cutting capacity of my saw is limited to 54" against the fence - so to trim a fraction off a large sheet greater than 54" is difficult if not impossible.

Anyone who has not suggested using a router/trimmer probably hasn't done it :) because once you do, it will be your tool of choice. Of all the tools mentioned, there is the least amount of vibration with a router or a planner.
 
Rob Markoff said:
An excellent suggestion - but impractical for many smaller shops. I have a big shop - but the cutting capacity of my saw is limited to 54" against the fence - so to trim a fraction off a large sheet greater than 54" is difficult if not impossible.

Anyone who has not suggested using a router/trimmer probably hasn't done it :) because once you do, it will be your tool of choice. Of all the tools mentioned, there is the least amount of vibration with a router or a planner.
Click to expand...

I hear you. My saw also has a 54" fence.

shop11.jpg


I use the panel saw in the back for rough cuts and do the final cuts on the table saw. The support table in front makes large cuts easier. I use Tenryu plastic cutting blades on both.

I sell acrylic on my site but don't get a lot of call for very large pieces. Like you said, cutting greater than 54" is a pain. Shipping pieces that large is even more of a pain so I most often pass and refer them to their local framer.

I had never thought of using a trimmer as I thought the vibration would be too much. I don't have a router-trimmer but I think I'm going to get a laminate trimmer with a counter top flush trim bit (the guide is on the bottom rather than the top) and play around with it.
flushtrim.jpg

Rather than use a bit that uses a straight edge clamped to the top. I will play around with just clamping to the table in front with the line to be trimmed exactly even with the front edge and use a laminate trimmer bit like you would with trimming a counter top.

I think I will like doing it that way because there is no math involved as with the trimming with a straight edge; just line up the cut line over the edge of the table trim away.

I am going to a tool auction tomorrow so maybe I will find one there.
 
I have a DeWalt laminate trimmer, and it has helped me out of a few jams. Works great when the frame is too tight for a slightly out of square painting, etc.
Never thought of using it for this purpose. I'll have to keep that in mind. Thanks.
:kaffeetrinker_2: Rick

(Before I got the trimmer I almost burned out my Dremel trying to rout out a frame... just not enough torque.)
 
Yeah they do get a might hot. :p It's amazing how much wood you have to remove just to gain a tiny smidgeon. Beats hacking away with a Stanley knife which I used to do.
 
Thank you, all, for your very helpful comments.
 
It is worth remembering that large modern frames flex out at their centers and when acrylic is tight, it can often be filed at its corners, so it fits there, while the centers can be allowed to move out, slightly. A plastic file is a very useful thing to have on hand.


Hugh
 
Artrageous said:
Shayla, I use an electric planer. I cut loads of plexi and from time to time, I run into that same issue.

The electric planer can remove anything from 1/32- 1/8 at a swipe. It's a convenient tool to have around. See if any neighbors have one. If not then a hand held electric sander or electric belt sander will do the job.

Just have the frame, plexi and cutting tool in the same area, so you can do trial fits after each pass.

It does make a dusty mess, so better to do it away from your fitting area.

Electric planer:
7698K_1.jpg
Click to expand...
What effect does the plexi have on the blade edge? Does it dull it faster than wood?
 
Wow you people are pretty good, you have that cutting thing worked out very well. WE of course just throw the thing on a floor standing panel saw and it's done in less time than it takes to get the acrylic on the saw. I am commenting only because I am so pleased to see that you framers out there in grumbleland have the straight scoop on how things are done! I appreciate hearing these things.
 
Acrylic Queen said:
Wow you people are pretty good, you have that cutting thing worked out very well. WE of course just throw the thing on a floor standing panel saw and it's done in less time than it takes to get the acrylic on the saw. I am commenting only because I am so pleased to see that you framers out there in grumbleland have the straight scoop on how things are done! I appreciate hearing these things.
Click to expand...


That's 'cuz you taught us so well.:thumbsup: Thank you!:)
 
shayla said:
Size is 39 x 60. Any ideas?
Click to expand...

A sliding table saw will handle that nicely. You can take off by 1/1000" at a time if you want, although you'd be hard pressed to move a stop less than about 5/1000" at a time.

You could also use a jointer - better control than a hand held planer.
 
David N Waldmann said:
A sliding table saw will handle that nicely. You can take off by 1/1000" at a time if you want, although you'd be hard pressed to move a stop less than about 5/1000" at a time.

You could also use a jointer - better control than a hand held planer.
Click to expand...

LOL, had access to a full service cabinet shop until it closed a couple years ago. Sold the Altendorf panel saw and the Busellato work station where you could shave as little off as you could program.
Routers/laminate trimmers seem the most accessible, and probably the safest for those not power tool savvy. Safety is the issue, and routers do generate a bunch of "dust". Use a dust collector if possible and a particle filter mask in any event.
 
mlmintz said:
What effect does the plexi have on the blade edge? Does it dull it faster than wood?
Click to expand...

I've used that electric planner for years and have never had to change the blade.

It's all I've ever used the tool for and it's never given me any issues with being too dull to do a great job. I don't need to use it all the time, but when I do, I'm able to trim off enough in 2 or 3 passes so the plexi fits with enough 'wiggle' room around.

Plexi with expand under certain environmental conditions, so if it's cut to fit snug it will bow out unevenly and leave waves.
 
Artrageous said:
Plexi with expand under certain environmental conditions, so if it's cut to fit snug it will bow out unevenly and leave waves.
Click to expand...

An excellent point :)

If you're lucky that's all it will do. I've seen oversized sheets blow open corners of frames that were well joined! The problem is that a 5/16" wide lip on a frame is often too narrow to allow for proper allowance of oversized sheets. That's another reason for a "real" frameshop :) to have either a router table or a small table saw so the rabbet of a moulding can be opened up (or become friends with a cabinet shop or a framer who does.)
 
Rob Markoff said:
If you're lucky that's all it will do. I've seen oversized sheets blow open corners of frames that were well joined!
Click to expand...

Oh, yes. Note to self...ask if 40"X 60" pieces are to be hung in an non climate-controlled space with southern and western exposures. The owners weren't too concerned, which is good, but the framing looked like ****. Good thing the videos used for national marketing exposure were taken before the frames failed. The ones that were in climate control or on an eastern exposure were fine, btw.
 
Rob Markoff said:
An excellent point :)

If you're lucky that's all it will do. I've seen oversized sheets blow open corners of frames that were well joined! The problem is that a 5/16" wide lip on a frame is often too narrow to allow for proper allowance of oversized sheets. That's another reason for a "real" frameshop :) to have either a router table or a small table saw so the rabbet of a moulding can be opened up (or become friends with a cabinet shop or a framer who does.)
Click to expand...


So, this wasn't my final outside size, but for the sake of an example,
if the usual mat size would be 39 x 59, would you route the frame out
to 39 3/4 X 59 3/4", then make the acrylic 39 3/8 x 59 3/8"?
 
shayla said:
So, this wasn't my final outside size, but for the sake of an example,
if the usual mat size would be 39 x 59, would you route the frame out
to 39 3/4 X 59 3/4", then make the acrylic 39 3/8 x 59 3/8"?
Click to expand...

That size isn't too large. I wouldn't route the frame out at all. I would cut the plexi about 1/8 smaller all around. I would put some sort of bracing on the back. It could be as simple as a piece of matboard stapled at both ends. I wouldn't pull it tighter though. It's purpose would be to keep the frame from flexing out and allowing the plexi to fall out of the rabbet.
 
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