Suggestions for inverse v carving?

[calapasha]

Anyone have an easy way to do a 3-d "negative" of a typical V-carved (simple) sign?

The idea is to make a carving in a panel (pattern mirrored) that can be used as a mold to cast a concrete sign that would look like a normal V-carved sign --

(I'd just rather machine MDF or foam and cast the concrete rather than rying to machine the concrete directly.)

[knight_toolworks]

just put a boarder around the vector and be sure to set the max depth. then select the vectors and the boarder and you have it.

[garyb]

Iso letters

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[calapasha]

hmm... Iso letters look like a good way to go -- I'm currently running partworks - any pointers where to look for references to Iso letters?

[garyb]

Don't know if you can do them in Partworks or not maybe one of the guys will answer you on that one.
They are a standard feature in ArtCam
You could also do them by offseting and cuting with a V-bit in partworks, won't look quite the same but will get a similar effect

[calapasha]

ArtCam -- must look into that sometime.

Arter puzzeling over this a bit more, I think cutting profile with a v-bit at the flat depth on the vector line would work if I could come up with an easy way of defining the remaining area that needs to be pocketed - this would allow a 3d inverse of a generic v-carving --

any ideas?

[btk]

Tony,
I have done many times and have found that it is much more efficient to machine the master (conventional v-carve) and
then to make a rubber mould off the master that can be used to cast the concrete.
You can use Rubber from Smooth-On or PolyTek.

Brian

[joe]

BTK,

We cut letters and panels for several concrete company's each week. Hardly a day goes by when we aren't making letters for them.

If you are only doing one or two signs, making a mold is not only time consuming, but real expensive. For one sign I would be hesitant to recommend that process. Several of my friends make molds for a living. There is a learning curve.

You guys do excellent work and I hope you don't take offence at my disagreement.

I think Beckwith has the answer.

Joe
www.normansignco.com./htm (http://www.normansignco.com./htm)

[btk]

Joe,

No offense taken, however in my experience, the amount of extra time to program, machine and then hand sand the flat and small detailed areas of the sign do not equal the expense of a thin coat of rubber (3/8" max) over a pvc v-carved master.

For other types of concrete items, I very often will machine the mould directly (as opposed to the master), however in the case of a V-carved sign, I go with a sheet of 1/2 AZEK and think layer of rubber.
The only exception would be a very large sign where the sanding/sealing of the negative prismatic letters would be more cost effective and sanding would be more accesible.

I have attached and image of a negative mould machined directly for a decorative wall cap.

Brian

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