Carving on a curve??

[myxpykalix]

I'm thinking about making one of those half round tables you set beside your lazyboy. And on the curve I wanted to carve some type of design. I'm thinking the degree of curve might be wider than my indexer could handle as a full round piece but thought i might be able to make a jig to hold a half round 90 degrees to the bit and have it only rotate less than half a turn to carve on the curve. Does that make any sense? Or would it be easier to carve on a flat thin piece and bend it and laminate it? I'd rather carve on a curve.

[paco]

V carving or 3D relief carving?

V carving may not do very well on a curved surface unless you're barely etching.

3D relief carving will (most likely) require model modification. I'm currently modifying a batch of model to be carve on chair backs (curved). Need the curved to be digitized as accurately as possible; that's the hardest part.

[lto]

Very interesing Paco. I have contemplated carving curved chair backs, I may need to get you to prepare my files. We have had backs laser engraved prior to bending with fairly good results, but this won't work with deep v-carved pieces.

www.barevillewoodcraft.com (http://www.barevillewoodcraft.com)

[Brady Watson]

Paco,
There's a guy in NJ that does very accurate laser scanning...


I can prepare toolpaths on any curve as well. Nobody really makes a decent v-carving strategy for curved backs, but there are other ways that I have developed to do this.


7484

-B

[paco]

Louis (?),

as said, V Carving (working with a cone tool or V bit and a 2D design) on curved surface with a 3 axis tool will/may not give the intended result. Even with the proper CAM strategy; what I've seen doesn't look good.

What I do is bending a 3D relief model to be fit on a curved surface.


7485

This part is easy; the more complicated/tricky part is to have a accurate "profile" of this curve so that many curved blank (chair back) are all looking the same.

The other part that can be tricky is the instructions sometime requested for the toolpathing step.

I'll be glad to do custom modeling for you or anybody else.

Brady,

I sure wont bother myself at digitizing intricate stuff; I'll send them to you.

The touch probe would more than enough for such curved surface digitizing though. In this case, the customer sent me a paper trace that I have scan and so far, we're within 0.5 mm... he is happy!

[menewfy]

I have been wondering if we have a peice of material that is curved and want to carve into it, is there a way the machine will know it is curved if we can't get it to lay flat? is this what you folks are talking about? or is this something different that I should start my own thread for?

Tim

[paco]

Timothy,

if you're CAM (3D) cannot limit the range of the toolpath in some fashion, you just need a part of the surrounding surface so that if follow the shape.

Does that make sense?

[Brady Watson]

Tim,
You'll need to tell your CAM program what the underlying shape is, and perhaps bump up the relief carving with that underlying shape. That's how the machine will know the underlying curvature when you go to create a toolpath. You can do this easily in ArtCAM or Rhino.

-B

[myxpykalix]

My original question was geared toward doing a relief carving as in Paco's example above, except it would be bowed outward as the outside round edge/front of the table as shown in the pic. I'm wondering if you could program it like you might program a relief on a column, but say only on one half because the diamter is too large to allow it to turn all the way around?
7486

[Brady Watson]

Yes. At least I know you can do it in ArtCAM like that by selecting only the region that you want to carve.

-B

[myxpykalix]

Ok, i guess what i'm confused by is how you tell the indexer/program what the diameter of the piece would be (because its raised up and larger than what the indexer can turn fully because of jig)? I guess it doesn't know/or care what my maximum radius that i can cut is right?

I suppose the first step is to make my radius, measure it, input that data when making my model.
I guess i was trying to figure out how the indexer would be controlled to prevent it from going too far in the rotation.