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Loading ...Scoring, Snapping and Profiling Acrylic Panels.
syrillian
As previously stated, there is more than one way to skin the proverbial cat when it comes to cutting acrylic.
Another tried-and-true method is scoring and snapping. There are, however, 2 limitations that come to mind. The first is the tolerable thickness that can be snapped. The second is the slight bevel that scoring can leave behind.
It is true that one could score and snap a piece of ½” acrylic, but the effort is not a reasonable price to pay unless one has no other option. As a general rule I do not score and snap acrylic that is thicker than 3/16”, and in complete truth I almost always use power tools as opposed to snapping.
The second issue is the small wedge that is created when scoring. The removal of material leaves a wedge shape in the acrylic, and when the piece is snapped, there is the smallest of bevels left behind. This is not a problem insofar as bonding, and if one is bull-nosing or rounding the edge then the point is moot.
In truth the only issue that I have found is one of aesthetics, and this only applies to clear acrylics as the slight bevel can be on the inside of a non-translucent panel. On clear panels, the offending edge can still be sanded and polished to leave a clean visible edge.
In addition to scoring, an untreated edge can be cleaned up and profiled with a scraper. Again, I eschew the scraper and gravitate toward power tools for profiling, cleaning and sanding panel edges. This is not to disparage the use of hand tools; it is merely a personal choice of what I am able to produce the best results with.
Here is an example of a scraper (3 profiles and a flat edge), and a scoring knife:
When scoring I try to use the most sturdy straightedge that I have. In this case it is a steel angle that has proven itself to be quite the reliable tool over the years…. they just don’t make ‘em like this anymore.
^^ When cutting (right-handed) the acrylic that I will keep is on my left and protected by the straightedge, and the refuse is on the right. Should I make a mistake and run off of the straightedge with the scorer (generally will only happen on the first pass) doing so will ensure that the marring and the error is on the piece that is not being used in the project. Note that I am placing a slight amount of pressure on the angle, this is to keep it snug against the edge of the panel; doing so will ensure a 90-degree angle once the snap is done.
It is prudent to consider the orientation of all tools and work to cover any eventuality that Moore’s Law will toss your way. I don’t know about anyone else, but I need all the mojo on my side that I can get.
Here is the scored acrylic.
For the most part, scoring half-way through a panel will be more than enough of a start to get a clean break. In this instance I scored less than 1/4 of the way through the panel.
Once the scoring is complete, place an object that is at least 1/2″ think under the panel (on the opposite side of the panel that is scored), and just off to the side of the score line. One can also use the edge of a table or other flat and sturdy surface. Hold the panel frimly in place and give it a bend, the acrylic should snap cleanly along the score line. In this instance I used the 1/2″ x 1″ acrylic guide for the router table.
This image shows the bevel that I spoke of earlier.
The snap is very clean. The only un-clean portion is the part that was scored. In the image above, In this instance the piece on the left would be the piece to use. The piece on the right could readily be ripped to a clean edge, and put in the bin for future projects that require smaller pieces.
Note: I have seen scoring tools that were beveled on only one side. Using a tool such as this will reduce, perhaps even eliminate the bevel altogether from the panel that is to be used in the project.
Profiling:
Here is a homemade router table.
Here is a shot of the profile edge that is aligned for the pieces that I will be profiling. This particular profile will yield a very subtle ogee-type profile; note that the there is about 1mm of vertical drop-off at the end of the curve. This will produce a very slight ledge. Although not technically an ogee, I use the word as a point of reference for myself.
Profiling thin sheets can prove to be problematic with a router. The issue lies in the guide bearing, and the amount of round-over to be applied to the edge.
Below is a shot of the router bit aligned for a smooth round-over. I have marked the guide bearing contact patch with a small arrow. This is to illustrate the problem with profiling thinner panels of acrylic.
The piece that I am profiling is ¼” thick, and I am using a 3/8″ round-over bit. As one can see the guide bearing is at its limit of contact. It is true that that router can be lowered to bring the guide bearing down, but that also reduces the amount of round over. There are smaller round-over bits that are compatible with rotary tools, but these do not have guide bearings. Although there is a surface to guide the panel, it is imobile and does not always do a great job.
I only have a couple of router bits, so I need to make do with what I have. One edge treatment that I like is the full bull nose. The same issue that plagues thinner panels also applies here.
It is simple enough to rout one side, but when the piece is flipped over, the guide bearing no longer makes contact in the same manner as the first side. This leads to a slightly off-kilter bullnose, but when the piece is polished the flaw is not noticeable except by the most discerning eye.
Here are a couple of shots of the eased edges on the panels for this project.
Once all the panels have been cut and profiled I make certain to mark each one with is position (Front, Back, etc.), the orientation (Up, Down), and which side is intended to be exposed.
The next step is to cut all inside cuts for fans, the I/O panel, switches and LED’s where applicable; I will cover that next week.
Thanks for reading.
oooo i`ve been waiting for the next instalment of this.
hadnt realised you were the syrillian from O/C.net
another great and informative write up dood. keep em coming
HeyHai, Urbtree….
Yes… that is me.
Thanks for the feedback. I am undecided on how much detail to go into as I do not want to produce some rambling Plog that is too wordy; yet I want to be specific enough that the small trip-ups can be addressed.
Thanks for reading, and I may introduce the hardware in the next post as well as covering the cutting of holes and the like.
Nice work with the acrylic, the finishes are pretty much perfect.
For anyone reading this info about acrylic though you might want to consider Polycarbonate if you dont have £100’s worth of tools, its easier to cut doesnt snap and break and the finish is almost exactly the same.
See link below for benefits!!!!!
http://www.youtube.com/watch?v=Hsls5ZPCUnE
Thank you for stopping by and commenting, bassdominator; and thank you for the link.
It is always good to have options, especially when it lessens the impact on the old wallet, and provides an easier medium to work with.
Your advice is greatly appreciated.
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