3mm or 1/8" plywood

[Robert Edington]

I am having trouble finding 3mm ply.
I see people talking about 1/8" MDF. Are Masonite and MDF the same thing? I can get Masonite. Masonite being the dark brown stuff, usually smooth on one side and rough on the other. MDF on the other hand is a tan color (in my mind that is!).
If Masonite and MDF are the same, is there a problem with fumes? I watched Russ's video on what materials to use and was curious if Masonite or MDF created toxic fumes.
Any leads on where to find 3mm ply in Houston?
Thanks again
RP

[Doug Fisher]

Masonite and MDF are not the same thing. MDF is usually a medium to light tan versus a dark brown.

I don't know if it is the same as masonite, but Lowes and Home Depot sell 4x8' sheets of 3mm ~ 1/8 inch "hardboard" that is dark colored and really cheap. The sheets I have bought have a smooth surface on both sides of the sheet. They will cut it down to size for you in most stores.

https://www.lowes.com/pd/47-75-in-x-7-9 ... el/3014304

[Tim Mellor]

Masonite is a brand but it is compressed fiber board. It should cut ok with a Laser but the edge might fall apart and crumple a bit as it has no glue binder. I used to make Cloth cutting templates from it as it was straight, heavy and the textured surface didn't slide around on the cloth. The downside is the edge is fairly prone to dings on the cut edges and the board can fracture if dropped. I just did a quick check and there is nothing nasty in it from what I could see if you cut it with a Laser. I don't currently have any on hand as all my old Kite templates are sitting buried in a container.

MDF should be fairly easy to find but it is made fairly differently and uses a Formaldehyde based glue as a binder. There is a move to reduce the glue content in some countries but suffice it to say the stuff stinks when cut viewtopic.php?f=105&t=4493&p=24523&hilit=pong#p24450 Make sure your extraction is vented well to the outside and when handled the edge will tend to carbon up and make your hands grubby unless you sand or wipe them over with a solvent per the linked thread.

Standard Plywood tends to use the same or similar Formaldehyde Glues but you can get Laser Grade ply which doesn't. I have been doing a fair bit of ply from this Australian manufacturer https://plyco.com.au/pages/laser-cut-plywood-collection it cuts much cleaner with a much nicer edge than standard ply but it is also 3-4 times the price. The edge will be a bit grubby more so with standard Ply but a quick sand with 220 grit takes care of it.

My most recent thing in ply is here viewtopic.php?f=113&t=3536&p=23579#p23579 made from 3mm Pine based Laser ply.

There is also a series of simple woodworking tools of mine here with SVG files for most viewtopic.php?f=113&t=4315&p=23663&hili ... ply#p23617

And this Mini ITX PC case here viewtopic.php?f=114&t=4247&p=23333&hili ... ply#p23333

[Robert Edington]

Thankyou for your replies. I went to a great lumber yard in Houston today. Clarks. They have everything. I came home with 3mm ply and 1/4" MDF. Now the hunt for Acrylic cutoffs!

RP

[Dave Vigness]

Watch the stuff you get in the home store. That ply and MDF, or even worse masonite, are not what you want to use in . The binders used in those materials is less than satisfactory for use in your laser cutter.

Premium MDF, and premium plywood, usually birch, use a binder that does not cause as much problems with your lenses and mirrors. The premium ply is finer / more layers with better binders. The premium MDF is as you describe, a light brown / tan. I only get a few sheets at a time from a hardwood supplier. An oversized sheet, 49 x 97, costs me around $11.50 per. She paints most everything, so I've not done much ply cutting since she doesn't want to seal it before painting it.

Done a fair amount of acrylic, but no where near Russ' capacity. Picked up some scrap at a local award shop. A lot of the acrylic suppliers / cutters are getting a backlog of scrap, China isn't taking it right now. I have a contact for Regal Plastics in Irving if you want it. He offered to give me a whole gaylord of it if I wanted to drive down from Kansas City and get it. I was VERY tempted... LOL

[Tim Mellor]

Watch the stuff you get in the home store. That ply and MDF, or even worse masonite, are not what you want to use in . The binders used in those materials is less than satisfactory for use in your laser cutter.

Refer to my earlier post Masonite doesn't use an additive binder/glue. This is in part why it falls apart so quickly when it gets wet. Masonite is in theory the safest of the trio discussed to cut as it should be just compressed wood fiber. https://en.wikipedia.org/wiki/Masonite

Thankyou for your replies. I went to a great lumber yard in Houston today. Clarks. They have everything. I came home with 3mm ply and 1/4" MDF. Now the hunt for Acrylic cutoffs!
RP

You might find the 1/4" MDF hard work with only 50W to play with. You might find 2 or even 3 quicker passes gets you a better less charred cut than one really slow one. On a router template I made recently from some 1/4" I ran two passes with my 40W and it looked better on the edge.

Also if you have a honeycomb bed avoid using it as it will be covered with residue from the cuts. A pin bed is much easier to clean. If you do only have a honeycomb bed then a Coffee machine cleaner works well to breakdown the residue or look for an Oxy type prewash cleaner (Nappy Cleaner) at your supermarket.

[Dave Vigness]

I passed over the 50W part. So yeah, 1/4" MDF could be on the ragged edge. You'll have the focal length on the lens to do the cuts with multi passes at least.

Do you know if you have a cutting nozzle or an engraving nozzle setup? Look at your air fitting and nozzle to tell the difference.

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You can also do the cut from each side thing. Saw a video somewhere, the guy made a jig out of acrylic so he could cut fro one side with a known edge, then flip it to the other side of the jug flipping the board over tt the other known edge. Looked like it worked pretty good but I haven't had time to try it with 3/8" on my 80W.

I can see how Russ is spoiled with acrylic. I can cut 23mm acrylic at 2mm/sec at full power. But if I get below 5mm/sec on 3/8" ( 9mm ) MDF I get a nasty BBQ !