# How to isolate this square

OK, this is out there- I have to use a shapeoko xl unit. I’m attempting to make a shower base form Styrofoam. These you can buy for \$90-200 dollars, but simply its a Styrofoam sheet sloped at 1% from edge to corner. I’m using carbide create 53 version- shower bases is 48" square, thus I am attempting to slope 4 panels that are 24 x 24" with on corner have a hold of 2" for the drain and 3.5" for the drain flange that will be pocketed out. I calculate 24 steps using a 1" flat smothering bit to taper the 1" sytrofoam down to .375 inch. thus a .75 degree slope. This will then be set in tile adhesive and the tile then set on top of the styrofoam . Will make 4 identical pieces with cuts set at 45 degree angle and each cut of of the 24 increments are a separate tool path that have been indexed a increment lower to make the slope. Was trying to use 3D Pro, but never could get a graduated slope designed. So Ive got my design in carbide create, but need to trim the vectors to not exceed the board by too much. I believe this will work, but I have attempted to use boolean, other art programs to trim the vectors without success. Ideas? Tom

Basically you’ll need to use the Boolean operation on each rectangle.

(Didn’t I do this design in 3D using Carbide Create Pro recently?)

So, given a square and a rotated rectangle:

Select the rotated rectangle:

shift-click on the square to add it to the selection as the key object (indicated by a dashed highlight):

Then apply a Boolean intersection:

(the square will need to be recreated for each iteration)

OK, I have made headway and can see the light at the end of the tunnel. Question,I will need to tile the cut to do what is needed for the slope. I can move the panel front to back with fitments, but what command do I put in the g-code to halt the router to do the panel movement and then rest and restart for finish the panel? as the XL has a dept of 16" I would need to go the 1/2 (12" ) then move the panel 12’ down and continue the cut. Side to side would be fine as it cuts 32 "

See:

If it’s at the half-way mark though, I think the easiest thing rather than moving the design through would be to just rotate it in place.

I am super new here and have no idea what I am doing, so this may be a terrible idea… but wouldn’t it be possible to shim one corner up the amount you want to take off then shim the two adjacent corners to half that distance, then let the opposite (fourth) corner rest on the table. Then if you just do a standard smoothing pass like you would to surface a spoil board? I know securing it might be an issue so maybe that’s why you wouldn’t do this.

Again I may have misunderstood what you are trying to accomplish and may be way off target

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Geoff, I considered this as a option, but holding the 1 1/2" thick styrofoam to the surface was the challenge. I’m using a shapeoko xl that offers a cut dimension of 16 x 33. I just came up from the shop and trying out the idea of the project. As I have 4 pieces of 2 ’ x 2’ foam board from Lowes, I have to do this on all 4 sheets as my shower is 40" x 40". What I discovered is that a surfacing bit cuts rapidly and smooth, and with a bigger dimension machine would work very well. but if I lay the board square to the cut table, the diagonal works fine till I’m about 1/2 way down the board then I run out of travel with the back and forward travel , Till this point, the taper is just as designed around 1 degree slope. I’ll graph this on some paper and see if I cut it on the diagonal if it can do it this may be an option, my trig math is a bit stale. If not , I am a member of the Louisville makers group and the club has a 4 x 8 shop-bot that I may use. 3D carving is another option, but again the lack of machine size torpedoes this also. Anyway appreciate your comments, for sure you’ll have great fun with your CNC, and you’ll make lots of new friends when you start carving signs or doing 3d CNC. The Carbide version 530 imports nicely line art graphics save as JPG files. These are all over the internet just search for line art. Choose something that is not real complex, save it as a jpg or png. then import and you can cut it after some cleanup. Tom

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