About to work with plastics for the first time.
Making a sign
Fairly large letters. 6"
1/4" sheet of HDPE plastic is what im going to be using.
My assumption is follow the basics, not much different, choose a proper endmill and carry on.
Pointers / Suggestions
TIA
See the video on HDPE at:
the Soft Plastic settings in Carbide Create should work well, but it’s less likely to melt if you can use a coated single flute tool
Let us know how it turns out. I am working on a sign for the Stone Fort in Nacgodoches Texas. It is an historical building used by the first Spanish settlers as a quasi government seat. It was later used by the Texas government and has been a store, bar and brothel. It is on the SFA Campus is on the national historical registry as part of El Camino Real. After submitting the proposal it has to go through a lot of bureaucratic approvals. I am going to make two proposals. One of cedar and the other multi layer HDPE with a white core. The letters will be white and whatever front color they pick. This a community project for the Wood Workers Club of East Texas. We donate the labor and my Shapeoko and they pay for the material.
So let me know how this comes out.
I watched the video on HDPE in that series and confused about a couple of things.
Winston references climb vs conventional cutting, I didn’t think in CC we had that capability.
Also, the reference to adaptive vs pocketing confuses me. I have seen people post about adaptive before but don’t understand the distinction or how to achieve it.
It’s looks like you are describing operations performed in Fusion 360, especially the adaptive clearing, which would be used to rough out a pocket, and then do a final cleanup with a pocket finish toolpath, or contour tool path.
Yeah, that is what I was afraid of 
The DOC was dramatically different. Although I think that the specified DOC for the non adaptive path was really really conservative and I don’t know if that was because the video was targeted for the Nomad.
I’d probably just choose the “soft plastic” tool options in CC and start testing.
HDPE has been fairly nice to work with in my limited experience with it. (Though I am a nomad owner so ymmv)
ive had no issues with HDPE on the nomad. It machines SUPER well.
roughing with a 1/4in 0 flute SpeTool endmill
1/16in 2 flute endmill for 2D pocketing
1/8in 2 flute ball endmill
should give you an idea
(obviously this is for the nomad 3)
I layed out my 1/4" sheet of HDPE and realized it would be best to wait and get some double sided tape to hold it down. The sheet will we 24" x 48".
I have never used tape on such a large sheet before.
Suggestions please and thank you.
Stay Safe
I’d recommend painter’s tape and CA glue for the hold down. Must double sided tape will gum up the endmill and can embed the residue in your cuts. Use clamps around the edges if you can, and you’ll want to babysit the cut in case you have a small part come loose.
I only have an SO3 XXL but recently cut out a bunch of easels. I used super glue and tape. It was the biggest project with tape I have used. If you are not cutting through you dont need to completely cover the bottom. If you are cutting through then I would cover the whole thing.
This is the second batch of these I cut that was even bigger.
I did not want to have to cut off all the tabs on so many objects. Painters tape and super glue, TiteBond Medium CA, has never let me down. I also use a long L bracket that is squared to the router to place my tape and material initially. If I will cut the L bracket I remove it when I get the glue dry. This project was 32" x 24" or so. So tape and CA are doable. Just be careful to line up your tape carefully if you dont cover the whole thing because you dont want CA glue on the back of the project.
Just to get this straight…youre lining the project with painters tape and then also lining the ‘spoil board’ and glueing those together? This would be a fair amount of glue?
Yes, see:
You don’t saturate the surfaces. Here is a pic of how I apply down each 2" row of tape. I buy my glue in 4oz bottles and it lasts months.
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