I am cutting a monogram sign out of 1/4" HDPE. The thought is to mimic the plasma cut thin metal monogram signs, but with less finishing or painting required (and since I don’t have a plasma table).
I’ve seen videos of people cutting HDPE without tabs, double-sided tape (or painter’s tape/CA glue), but they are using vacuum tables on larger machines. The smaller pieces simply get flung out by the bit and land wherever they land and the machine doesn’t seem to care.
I’d prefer not to have to clean up lots of tabs, if possible. I plan to put screws in the 4 corners and tabs around the outside profile and larger pieces to keep them from moving when it is cut , but given how soft and easy to cut HDPE is, Im considering just cutting the rest without tabs.
I have extra HDPE to remake it if it goes sideways so I figured it was worth a shot to try it.
Is this a horrible idea?
I cut HDPE all the time. I do not recommend letting the parts float freely. It’s very common for the pieces to chatter back and forth, and the cutter will leave ripple lines on the parts.
I use very small bridges, 0.05" tall, and 0.05" long. They are very easy to trim off cleanly with an sharp blade. On occasion, the pieces get jammed up and snap the cutters I use.
My guess is that you would spend less time cutting bridges, than you would re-programming parts.
Good luck!
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I’ll try that, thanks! I definitely don’t want to break the 1/8" O Flute End Mill.
I cut a prototype out of plywood without tabs initially using painter’s tape and it jammed the machine because the plywood wasn’t flat and it didn’t adhere everywhere. I then cut a 2nd out of plywood with tabs and I let CarveCo insert the tabs automatically, which seemed to end up a bit on the excessive side. It took an hour + with a jig saw and Xacto knife just to get it sort of looking ok.
On HDPE, using VCarve (or CarveCo), do you let it automatically add tabs, or do you do it manually? Also, do you do 4 tabs per internal piece, or 2?
Again, thank you for the advice.
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(Also, I realized after posting this that this topic probably belongs in the Materials section of the forum. Sorry. 
)
I normally try to out at least 3 tabs/bridges on small parts. I position them manually each time. I try to always postion them on a straight section (not a curve) so its easier to cut with a knife after.
Seems tedious sometimes, but when I started doing it, I quickly found faster and faster ways to do it quickly, so its good practice.
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Thanks Mike!
Well, I finally received my HDPE and cut my sign using your recommendations and it mostly worked. The issues I encountered were not related to the tabs, they were related to how thin the 1/4" HDPE is. Basically, the end mill is an upcut (I think) 1/8" O Flute and i simply screwed down all 4 corners of the material to hold it meaning it flexed (lifted up) when the bit was cutting areas that weren’t near the screws. When it lifted up, it cut through the tabs which meant there were pieces getting jammed up which wasn’t ideal. I got lucky that I didn’t break the end mill.
I wrote all of this to ask:
Should I use thicker material (3/8" or 1/2" versus 1/4" HDPE) to prevent flexing, or should I use larger tabs?
If I hooked up the vacuum table that came with the machine (it s a homemade setup using a whole house vacuum with 4 zones that are 24"x24"), would that hold it and more specifically, the small pieces that are being cut out? (My guess is no due to the small surface area.)
As always, any advice is greatly appreciated.
This would help. There are probably better ways to do it without “throwing more material” at the problem. I didn’t realize you were cutting thin stuff. I have always had problems with the chips getting thrown under the material and lifting it up.
I also normally use a O-flute upcut bit, but for thin stuff, I would be tempted to try a downcut bit.
The vacuum table would definitely be a good idea. That would be my preferred way to do it.
I have also had success with this method…
- Run the program without the material loaded. Set the cutter to cut into the spoilboard a little, 0.025" maybe.
- Then apply double sided tape to the spoilboard to hold the sheet down. You don’t want the tape to gum up the cutter, so use the marks left by running the program the first time to show you where NOT to apply tape.
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I just cut the same material. I just used construction double sided tape. Worked just fine except when it cuts through, the tape will gum up the bit so i just use a ss brush to get it out of the flutes
Thanks. I have some double-sided tape arriving today.
Attached is what i cut. The customer wants metal but I don’t have a plasma table. I’m trying to see if I can achieve something close with HDPE.
I don’t like the shiny look or the scratches, so I plan to sand and paint it for the final look.
If this work continues, I’ll buy better HDPE for next time. This HDPE was a quick Amazon purchase.
(attachments)
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Nice. Very intricate! I can see why holding it down is a struggle!
HDPE us typically available in a smooth glossy finish, and a textured/pebble finish (looks like an orange peel) The textured finish is the way to go for most signage, as it hides scratches so well.
Very nice. Lotta intricate details in that for sure!!!
