Tag Archives: jig

112: Three-Ply Acrylic

It’s kind of amazing that it’s taken me this long to get to this project; when 52 Lasers was first conceived, using three-ply acrylic was on the first draft of our potential projects list. Now, more than two and a half years later, I finally have a project that requires this unique material!

Rowmark's convenient visual representation.
Rowmark’s convenient visual representation.

Three-ply acrylic is similar to the two-ply acrylic I use very often, except the thin cap layer is applied to both sides of the main acrylic substrate. While most of the badges, magnets, and other pieces I make only need one side to be engraved, certain items like medallions or coins might need both sides engraved, and this is when you’d use a three-ply option. This month’s project is a great example.

 

A bunch of SCA tokens celebrating an elevation.
A bunch of SCA tokens celebrating an elevation.

A couple of dear friends of ours are part of a group called the Society for Creative Anachronism. While I’d like to explain what that is for you, I couldn’t possibly do better than the SCA’s excellent portal for curious newcomers. Dave got in touch and explained that his husband Jim was going to be recognized for his accomplishments in the Society, in a ceremony called an elevation. For the event, they wanted to distribute small tokens, in SCA appropriate colors, featuring Jim’s moniker in Chinese (凱曾, Kai Tseng) and the triple rapier logo of the Order of the Masters of Defense. I’ve always used wood for tokens that need both sides engraved up to this point, but it was far easier to get the colors Dave and Jim wanted by using the three-ply LaserMax acrylic from Rowmark.

When you’re engraving two-ply material, you don’t really have to worry too much about the back face; people aren’t going to be scrutinizing a blank back surface, so imperfections caused by the manufacturing process aren’t a big deal. That’s why two-ply materials only ship with mask on the front surface. Three-ply material has mask on both cap layers, and while you want to remove the mask from the side you’re engraving first, you definitely want to leave the mask on the bottom side. That’s because those vector cutting scars—plastic residue, honeycomb table impressions—are going to damage that side if you don’t. It’s okay to engrave the reverse side with the original side unmasked because you won’t be doing any high power vector cutting in that final step; it’s just surface engraving, which doesn’t cause those kinds of issues.

Red tokens placed upside down in the makeshift jig.
Red tokens placed upside down in the makeshift jig.

Conveniently enough, just cutting the shapes out in the first pass automatically creates a makeshift jig—or template—out of the leftover material. As long as you send the second half of the engraving data in the same exact positions as the first, all you have to do is flip the shape over and engrave again. Now, this requires a symmetrical shape, or else you’ll have to take flipping into consideration and cut extra pieces out of the material that will form the jig. You also want to remember to take the mask off of the flipped token’s new front side before engraving; firing the laser through that thin plastic layer will usually create a sticky mess.

With all of that in mind, it’s fairly simple to process three-ply material in a clean manner. You’ll still have to wipe down the edges with a light alcohol or a solvent similar to Goo Gone, but that’s usually the case with two-or-more-ply acrylics anyway. For how simple the whole process is, I still managed to muck things up, and I lost a whole set of twenty yellow tokens on the first pass due to a technical issue with the laser that I still haven’t figured out.

Unexpected markings ruined a whole batch of tokens.
Unexpected markings ruined a whole batch of tokens.

Once in a while, when raster engraving, the field I’m engraving will be speckled with tiny additional engraved dots. I can never predict when it happens, and just rebooting the system fixes it, but it always loses me a piece or two.

Token stacks.
Token stacks.

I also noticed with this project that my laser alignment isn’t perfectly perpendicular to the engraving surface currently; if you look a the picture of the token stacks above, you’ll notice the slight skew in the 1/8″ thickness of the tokens. I think this is due to a misaligned mirror #3, but it’s difficult to know for sure and I might end up having to replace the mirror #3 assembly with a factory-calibrated one.

If any of you have any tips for cleaning the laser-cut edges of a two-or-three-ply piece, any ideas on what might cause the rare engraving field speckling, or any suggestions on how to realign the beam path across the surface, let me know in the comments below!

73: Bevel or Miter Guide

This week’s project is a totally unintended project, a plan C, made by necessity. Both plan A and plan B didn’t come to fruition because we didn’t have the tools needed, so for plan C , we decided to make one of the missing tools!

Plan B involved making a box.  With the laser alone, we are confined to either making box joints (which we explored with cool Tetris blocks in Week 14) or butt joints.  Butt joints are made by butting the end of one piece against the side of another piece and gluing it in place.  Neither of these seemed appealing because I wanted more finished looking corners – I didn’t want a laser cut edge visible.

Saw Max with the SM600 flush cutting blade.
Saw Max with the SM600 flush cutting blade.

A miter joint hides the cut edges by beveling the wood at a predetermined angle.  To get a box, you bevel at 45 degrees.  Two 45 degree angles together equals a 90 degree bend.  There are specialized tools that help make this process easier, such as miter saw or a table saw with a miter gauge.  I own neither of these things (but if I had the space I wouldn’t be too hard to convince to get one!) What I do have, though, is a Dremel Saw Max with miter cutting guide.

Line up, ready to go  with high hopes!
Lined up, ready to go, with high hopes!
Dremel guide channel
Dremel guide channel
Cutting stopped short
Cutting stopped short

The miter cutting guide’s sole purpose it to cut miter joints, so I thought, job done!  Except, not.  The beveling portion, the line in the v shaped channel, is sized to only fit crown molding.  Even though the channel was plenty long for the piece I was working with (10 inches), the opening the material is supposed to sit in is only 5.5 inches wide.  We tried it anyway – clamping points are inadequate for such a long length and the plastic legs on each side of the opening made it impossible for the 3″ flush cutting blade to get through.

Small gap to bevel wood in the Dremel Miter Guide - only 5.5 inches
Small gap to bevel wood in the Dremel Miter Guide – only 5.5 inches.  Why do they even go up to 7?

I wasn’t ready to give up on Plan B just yet, so Ryan and I took and emergency trip last night to Home Depot.  There were no options for cutting guides that were larger than crown molding available.  I found myself standing for quite a period of time in front of the cheapest little table saw they had, the Ryobi 10 inch 15 Amp table saw trying to decide a) if it was foolish to buy a $129 tool for a blog post, b) if we could learn to use it in one night, and c) where the heck the thing would go in our house or tiny garage.  I’m a tool girl, so it wasn’t a stretch to justify the money, but the space issue is real, you guys.  My garage just barely fits my boat of a car. And I just couldn’t figure out a space in the house where sawdust wouldn’t be an issue.

An ever-helpful Home Depot employee came over to help, and he thought the laser cut piece we brought with was the bees knees.  It was his suggestion to use the laser to fix this problem.  This got the wheels turning and with a little discussion and sketching, Ryan was off to make a miter cutting jig.

Jig in place!
Jig in place!
45 degree wedges
45 degree wedges

It’s pretty basic – two flat surfaces between which we would insert tabbed pie shaped wedges to get the angle we wanted.  We cut them at 45 degrees, but really any angle will work.  We left the wedges unglued so they could be interchangeable. The flat surface on the bottom gave ample opportunities for clamping.  The flush blade rests on the flat part of the jig – to rest on, keep straight and create the 45 degree angle.

Because this is getting wordy, I’ll do my point list on what I learned:

– Our plastic clamps stink. They really didn’t do a great job holding everything down tight.

Lining up the cut
Lining up the cut

– There is no point on the jig – being made with 2 flat pieces of wood, it has a bit of a snub nose.  We pre-marked the line we wanted to follow with the laser, but had to eyeball where to put the guide in order to get the blade there.  If we wanted to make the wedges permanent, we could use their points slotted in the flat piece and glue them in for stability…(I’m not sure how to explain this one…maybe I’ll make one for next week!)

Taped up jig
Taped up jig

– We had to tape the wedge edge together. Even though the tabs were snug, pressure of the the tool at the top caused the bottom point to raise.  Gluing would solve this issue as well.

– I need a workshop!  With proper dust collection. And room for a table saw. And clamps.

–  It’s hard to work with perfection.  Our first cut was terrible, but they got better by cut number three.  We are spoiled working with the laser, honestly, where it is perfect every time.

Final Results:

This is one where practice made perfect – we made several cuts before coming close to what I’d call usable.  But it is a much cheaper work around than buying a table saw! (…I still want a table saw.)

This is a better side by side comparison of the cuts...not totally even.  But they were getting better with practice!
This is a better side by side comparison of the cuts…not totally even. But they were getting better with practice!
Resulting 45 degree cut (3rd try)
Resulting 45 degree cut (3rd try)
Outside joint.  Definitely needs some sanding!
Outside joint. Definitely needs some sanding!
Inside joint.  There is a bit of gaping, but wood glue will fix that.
Inside joint. There is a bit of gaping, but wood glue will fix that.