Hi everyone. I am a woodworker and I have been asked to produce a batch of 32 corbels for a ceiling restoration. I would try to use a CNC machine starting from a .dwg file.
Is it possible to draw first a .skp file and then export it into a dwg one?
At the moment I only have a picture of the original corbel:
Isn’t that a plaster cast? Usually the plasterer creates a new silicone mould based on the best preserved and cleaned original, and the new parts are cast in gypsum plaster.
A single photo like that is not enough to create a 3D model of the part.
And your example is deformed by the many layers of paint etc that have been applied to the object. Possibly latex paint as there are some cracks caused by the thick paint layer shrinking.
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Many thanks Anssi.
It’s wood, possibly fir, hand crafted … and a lot of layers of paint!
So, you think a pure sample is needed to design a 3D model?
The first option is to make a wooden (tulipier) corbel (I already found a 5-axes CNC, but they asked me for a .dxf file) to be painted (grey is the original ceiling).
Plan B is to create a mould from the best preserved piece and replicate with epoxy resin.
It is certainly possible to create a 3d .skp from the photo with a bit of guessing and a few measurements, but not by a beginner.
The question really becomes, is this a commercial request. Are you interested in someone creating a version of the corbel for a price. It would be quite a valuable model as it would allow many repeats.
Is your client looking for something off the shelf or are they interested in a bespoke job and the costs that would involve.
Anyway, just throwing some thoughts around.
I appreciate your comments and try to answer.
- is this a commercial request: my task, as a professional woodworker, is to accomplish a job. So, I just need a 3D file to make a batch of wooden corbels. I understand your point: I don’t need to “own” the file, I just need to use it, once.
- Are you interested in someone creating a version of the corbel for a price: I am not a beginner in Su, but I think I’d have to learn too many modeling aspects I never tried before, in order to get a satisfactory result. I am quite in a hurry and this is not the only problem I have.
- It would be quite a valuable model as it would allow many repeats: you are right. See point 1.
- Is your client looking for something off the shelf or are they interested in a bespoke job and the costs that would involve: my job is part of the restoration of a Liberty villa, downtown Milano. Nevertheless the corbels will be under the ceiling, at - I guess - 5 or 6 meters high. Which means that some details will be almost invisible. The actual ones are clearly handmade, nice job by some carver: no more carvers existing in my region!! Everyone do prefer CNC machines …
Thanks for make me think
g …
Another option may be a 3D scanning service.
Ideally you could take (1) Corbel down and send it to have it scanned.
I don’t personally have experience with this, but have read the scan file can be quite “dense” and likely would require further refinements but likely as accurate to original carved piece as you would get. (If that is requirement)
Edit:
Probably good idea to carefully strip off layers of paint prior to scan.
C
Not only cnc and 3d scaners exist. It is a other way:
Consider using a wood copier. On YouTube you will find many instructions on how to make such a device from plywood yourself. An experienced carpenter will need one day to build a copier.
Regards
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Just an idea if you ever decide to learn and model this type of object yourself
Apply this technique with SketchUp tools
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Thanks Webski Mihai for your suggestions! Very interesting, really. Do you think such a file could be transformed in a “CNC readable” .dxf?
In general, SketchUp creates a mesh of triangles to build solids (as STL). This is where the problem lies. With uncomplicated surfaces, you can be tempted to convert to a model acceptable for the CNC. In your case, it’s rather difficult. Here’s a link to how you can do it with Fusion 360.
I would choose the copier for faster and cheaper result or SolidWorks if you want do this on CNC.
but maybe I’m wrong. I have long brake in CAM
Regards
There are a few ways to come at something like this. It sounds like they will be getting paint, so:
The corbels could be modeled in SU, and sent to the machine as an STL and carved in wood (or FAR better, six or eight pound HDU foam).
The fact that there are 32 of them though would lead me to molding and casting them. They could be done in urethane resin and could be hollow and light.
If we were doing this (we are a prop-shop), we would probably carve a master with a combination of CNC and hand carving. Our machine is three axis, so I would model the body in simple vertical slices and cut it that way from HDU on the machine (“2.5d”). We’d carve the leaves separately and apply them. Then we’d do a silicone mold. Depending on the scale, the parts could be molded and cast as halves or roto-cast in single pours.
Questions:
What IS the scale?
How much time do you have?
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Many many thanks to everyone.
Just an update.
In early July I run a sample on a 5-axes CNC machine and - please don’t ask me the cost 
- and the result was not very satisfactory: a further manual work would be needed to give a “volume” to the final structure. See below:
So, even because of a delay in the project (august in Italy … may be someone knows …), I decided to spend my vacation carving all the pieces … 
Just a bit of practice with a coulple of scraps in order to optimize the cut sequence, and now I’m almost ready for finishing all of the corbels.
Following a sample of hand carved corbel:
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