1/64th Inch Birch Plywood Cutting

[John Esberg]

Well, it looks like I found one tough little material. I've been using 1/64th inch thick Birch Plywood made by Midwest for making HO/HOn3 scale modeling pieces. At 1/87th scale, it means pieces may only be 0.031" wide.

I've found a few important things about this material. First, cut it on a vector cutting bed. Obvious, but still worth mentioning.

Second, cut the internals first. So if you are using CorelDraw, that means make 2 copies of the curve, separate them into 2 different colors, and chop them apart for internal & external, and then finally group them back together again. Since I have a ULS machine, I cut black and then red. So internals are black.

Next, you can't allow this plywood to pop up on you while cutting. This requires "tabs", approx. 0.02" breaks in the outside of the curve, to hold the piece down on the original material while cutting.

Go for only 1 pass. If you pieces pop out of place, you'll only make charcoal. So, keep it simple.

Forget rastering. It's not normally cost effective and at this scale its too small for most people to see. It can really be a bad idea if they use a thick coat of paint after you sell it to them.

So far I haven't found any good cutting specs. Does anyone have a good formula that they can share?

V/R,

DAK

[Lee DeRaud]

The biggest problem I've had with cutting the stuff is that it tends to burn: not edge-charring, but actual burning that distorts the cutline. I've had simple things like circles end up looking like leaves that the grasshoppers had been nibbling at. (Air-assist would probably cure that...if I had it.) The cut pieces tend to stay flat, but I'm in a pretty dry climate.

OTOH, rastering works great: I use this stuff for business cards. The beam rasters away the light outer layer and turns the darker middle layer (and/or the glue) almost black. Due to the burn issues, I just "score" it with the laser and cut them apart with a utility knife and strait-edge...probably faster that way anyway.

Settings for ULS VL200 (25W nominal, but I think mine runs a bit 'hot'):
Raster: 100P, 75S
Vector: 50P, 2S
(Next time I have to cut it, I'm going to try 100P and more speed, see if the flaming dies down.)

[Mark Rios]

Soooo...is that 1/64" Birch plywood 7 ply or 13 ply?


How do they make plywood THAT thin?

[Dave Jones]

How do they make plywood THAT thin?

3 layers of .020" veneer

With the Epilog driver I just make sure the inner cuts are lower in the list in CorelDraw's Object Manager. It cuts them in order from bottom to top. So I can arrange the order to make cutting a sheet more efficient, as well as making sure all inner cuts happen before outer cuts. The sheets I bought from Sloans were very flat, so I didn't have to worry about clamping them. Just place them on the honeycomb grid and start cutting.

I can't imagine cutting without air assist. I always use it.

[Lee DeRaud]

3 layers of .020" veneer

Uh, that works out to about 1/16"...which oddly enough is the one thickness I've never seen from Midway: my local hobby and craft stores have 1/64, 1/32, 1/8, and 1/4, give or take a conversion to millimeters.

But yeah, it's three-layer up to 1/8", five-layer for the 1/4".

[Lee DeRaud]

With the Epilog driver I just make sure the inner cuts are lower in the list in CorelDraw's Object Manager. It cuts them in order from bottom to top.

If John is using the 'advanced' ULS driver, it ignores the Corel object order unless he manually shuts off the path optimization. I don't know what its normal algorithm is, but it gets pretty odd-looking sometimes.

[Dave Jones]

oops. You're right. I use 1/16" that I get from Sloans, so I had that in my head. 1/64" 3-ply would mean .005" plies. Man, that is thin veneer.

[Kim Vellore]

Dave,
How do you change order using object manager? I right click->order->...
Also using epilog driver how does one define direction of cut? for example If I have to vector cut multiple parallel lines the laser cuts the first line from left to right then the second line also from left to right I wish I could make it go from right to left for the second line on the way back. It could save me some laser time.
I have been using 1/64 ply for a while for making all my Z scale train stuff, I am still looking for thin laserable plastics as thin as 1/64". Most plastics I cut leave some melted edges that is why I am still looking for plastics that cuts like acrylic. Thin acrylic at 1/64" are hard to come by and very expensive.
You can see some of the things I do with my laser at
www.kimsartshop.com

Kim

[John Esberg]

Yep, I use the advanced driver. I always have it set to "optimize and sort" in the advance settings tab. It's standard practice to have it set for me. I've found that have it on that mode along manually aligning pieces can reduce working time by up to a third. It's pretty common for me to spend a lot of time cleaning up and optimizing other people's files when I first get them, especially if I'll be running large batches.

I recently bought one design from a friend nearby where I optimized it, rearranged it, and squeezed it into one less file for cutting. I ended up saving 12% material and 30% time per 2 hour job. Not bad!

As for cutting specs, I'm down to 15% pwr/3% spd range, but I've run out of material and I can't find any in the local area. I'll have to drive down south tomorrow to find more.

DAK

P.S. Happy Holidays!

[Lee DeRaud]

As for cutting specs, I'm down to 15% pwr/3% spd range, but I've run out of material and I can't find any in the local area. I'll have to drive down south tomorrow to find more.

Hmmm...I'll have to try it using a lot less power: the settings I use were originally extrapolated down from what worked with the 1/8" to the 1/32", then to the 1/64"...could be that the power required isn't really linear with thickness.

[Dave Jones]

Also remember that keeping the PPI/Frequency low can cut down on the charring on the edges.

Kim, I change the order of objects in the Object Manager simply by grabbing the item in the list and dragging it. You can also move a group of items from random positions in the list into a new position by selecting them on the screen and then grab one of the selected items in the OM list and drag it to a new position. All the other items go with it and are moved right next to each other in the list. I also tend to group things in layers to make it easier to keep track of what they are, and layers also are engraved in order, from bottom to top. So it engraves the lowest item in the lowest layer and works it's way up.

As for the direction of engraving lines and shapes... When you select a shape you see small boxes on each of the virtexes (endpoints) of the line or shape. One of them is larger than the rest. That one is the start of the line or shape. The Epilog driver will start engraving the line at that end. If you select a line, or several lines, and then go to the Shape Tool (the tool you use to edit nodes on a line) then click the "Reverse Curve Direction" button on the toolbar you'll see the large box move to the other end of the line. With a set of parallel lines you want to select every other one and then reverse them so that the start of one line is near the end of the next.

[Mike Hood]

Great tip Dave.

I was just doing that (the hard way) last night. I'll sure make use of your "reverse curve dirction" idea. Never even crossed my mind.

[John Esberg]

20/3/1000/1 Pass / 0 Height Adjustment

Tab Size: 0.015"

Gap Size Between Pieces: 2/87" (0.023")

Due to material distortion from heat, weight is needed to hold it down. Don't risk this aspect in cutting. If needed, break up the cutting into multiple sections to move the weights around to accomidate.

Congrats! You just saved a few man-hours in laser time, please make a donation to this website to say thanks. Lets keep this great resource free!

[Kim Vellore]

Dave,
That is a great tip. When I was initially setting up my laser I tried to flip lines to see if it would change direction of cut and just realised that I have been flipping North-South on a East-West Line. Now I know what to look for.
Thanks again to all for all the tips and tricks.

Kim