Engraving into existing curved objects and intarsia question

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ALuomala
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Joined: Mon Feb 17, 2014 7:30 pm
Location: Alberta, Canada

Engraving into existing curved objects and intarsia question

Post by ALuomala » Fri Feb 21, 2014 1:44 am

I was wondering what the process would be for engraving into an existing curved object. I am primarily interested in getting a SO2 for carving (hobby primarily, but perhaps get some paid work out of it), and I was thinking of different objects that I could engrave/carve. One of them would be guitars (bodies and necks/headstocks).

The way I envision this being done is this: obtaining a 3D model of the object and setting up the cutting path based off of that. Well, that sounds easy, but is it doable? Then I wondered if it would be possible to have the SO2 and software act as a "probe" and determine the profile/geography of an object. The way I see this happening is having the operator maneuver the "probing head" around the object (to determine the perimeter) and then over it (to map out the elevations). I don't know if there is software out there that would be able to construct 3D objects from this data, or if there is an automagic way for this to occur.

I have seen software that uses lasers and cameras to do this (link here), and was thinking that one could mount a decent quality webcam and lasers onto the SO2 to do this, and then once the 3D model is created, use that to create the carving paths. Otherwise any model that is used (whether created manually in a 3D program, or found on the web) would have to be bang-on AND the object would have to be placed exactly into the cutting area. I figure that if the object stays in the work area for the whole process (determining topology, etc; computer does it's heavy lifting; and then allowing the SO2 to engrave/carve the object.

Another thing I was looking at doing was using the SO2 to quickly mill out pieces of wood for intarsia woodworking projects (see example pic below). One thing that is nice to do for these types of projects is lining up the pieces to take advantage of the grain of the wood. To minimize waste on the wood, I was thinking of placing the wood stock into the work area, using the above-mentioned webcam (mounted to top of enclosure, facing down to work area, both to take images for use in the next step, and also monitor progress whilst SO2 does it's magic) to snap a picture of the wood, and then import the image into Illustrator/Inkscape/etc to rotate/move the shape(s) I want cut out to maximize the use of the grain and minimize waste. I kinda pulled that idea out of my butt, but is this something that is done in the "real" CNC world? Exotic woods are expensive, so I want to minimize my costs and also maximize the beauty of the finished project. I like the idea of using the SO2 to minimize what (to me) is mindless labour (cutting, shaping, etc) and then doing the last bit of heavy lifting by hand (final shaping, sanding to fit together tightly).

Image

Any input here would be greatly appreciated. If I can justify the expense of purchasing the SO2 to this type of work to myself, it makes it easier to convince my accountant (wife) that this is a worthwhile endeavour. It's funny that I stumbled into DIY CNC machines whilst researching a decent quality scrollsaw, since the SO2 ends up being not a lot more expensive that a decent Dewalt (or equivalent) scrollsaw, but infinitely more versatile. Here is what I will likely buy as a multi-purpose cutting tool: Rockwell BladeRunner.
ShapeOko2, serial ??
DW660 spindle;
Upgrades: 900mm X axis and 1000mm Y axis; ACME Z Axis; modified MDF wasteboard with t-slot
Primary usage: wood crafting (signs, plaques, and ultimately a CNC-made electric guitar)

DanMc
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Re: Engraving into existing curved objects and intarsia ques

Post by DanMc » Fri Feb 21, 2014 2:05 am

To your first point- that requires a pretty sophisticated CAM program to pull off, DeskProto does it, I'm sure there are others as well but you will pay for that capability. As far as I know there is no open source/free solution as of yet.

Second point, I know Mach3 can do probing, if you are probing a piece of wood or other non conductive surface you need a special probing attachment, basically a precision microswitch that mounts in your spindle.

There was a kinda third point i.e. maintaining alignment, it's not that hard to get something lined up pretty precisely on the mill bed, just takes some patience.

And fourth point, there was some software developed recently that does just that on a laser cutter, webcam to binpacking type calculation to use spoils of previous pieces, not sure what the name of it is or if it's open source. I find it's not that hard or time consuming to do manually.

ShapeOko would be great for intarsia projects.

WillAdams
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Re: Engraving into existing curved objects and intarsia ques

Post by WillAdams » Fri Feb 21, 2014 2:10 am

Yes, there are probes for machines which one can use w/ control software to input 3D coordinates to make a mesh --- Mach3 has support for such if memory serves.

There are also systems for doing this using a camera and photographs taken from many different angles, and home-made 3D scanners using webcams and laser pointers --- not aware of anyone that has attached such to a CNC machine though.

Major negative for a CNC machine is the cutting width is quite a bit larger than a scroll saw, resulting in more waste.
Shapeoko 3XL #0006 w/ Carbide Compact Router w/0.125″ and ¼″ Carbide 3D precision collets

ALuomala
Posts: 136
Joined: Mon Feb 17, 2014 7:30 pm
Location: Alberta, Canada

Re: Engraving into existing curved objects and intarsia ques

Post by ALuomala » Fri Feb 21, 2014 3:13 am

Thanks for your input, fellas.

For the CNC machine cutting-width/waste issue, I'm not too concerned, as I suspect by cutting manually I would have been throwing away a lot of spoiled pieces anyways ;) I don't plan on doing super-fine work (there are some that are breathtaking in their complexity).

If Mach3 has that probing capability, that would be a major bonus, so I wouldn't have to invest in more software. Edit: here is a link to something on eBay. Under $100, and .005" accuracy, so worth investigating.

I kinda figured that there would be software/hardware solutions at the commercial/industrial level, but don't want to go down that road, obviously.
ShapeOko2, serial ??
DW660 spindle;
Upgrades: 900mm X axis and 1000mm Y axis; ACME Z Axis; modified MDF wasteboard with t-slot
Primary usage: wood crafting (signs, plaques, and ultimately a CNC-made electric guitar)

Oud
Posts: 23
Joined: Sat Dec 07, 2013 5:54 am

Re: Engraving into existing curved objects and intarsia ques

Post by Oud » Mon Feb 24, 2014 6:52 am

DanMc wrote: Second point, I know Mach3 can do probing, if you are probing a piece of wood or other non conductive surface you need a special probing attachment, basically a precision microswitch that mounts in your spindle.
Just put aluminum foil over the piece, work it on so it covers nice and flat Attach an alligator clip to the foil and another to the endmill/probe. Won't work for every case.... but how many things work for every case =P
Stock Shapeoko2, First pre-order batch.

ALuomala
Posts: 136
Joined: Mon Feb 17, 2014 7:30 pm
Location: Alberta, Canada

Re: Engraving into existing curved objects and intarsia ques

Post by ALuomala » Mon Feb 24, 2014 5:19 pm

Oud wrote:
DanMc wrote: Second point, I know Mach3 can do probing, if you are probing a piece of wood or other non conductive surface you need a special probing attachment, basically a precision microswitch that mounts in your spindle.
Just put aluminum foil over the piece, work it on so it covers nice and flat Attach an alligator clip to the foil and another to the endmill/probe. Won't work for every case.... but how many things work for every case =P
I was thinking of using this trick (it seems a little too good to be true ;) ). Thanks for the confirmation that it works (albeit not foolproof). This will be good for things I don't want to damage, and for things that can be sanded/cleaned I may use foil tape (stuff used for sealing heating ducts) or something similar (something conductive, obviously).

Thanks again.

Allan
ShapeOko2, serial ??
DW660 spindle;
Upgrades: 900mm X axis and 1000mm Y axis; ACME Z Axis; modified MDF wasteboard with t-slot
Primary usage: wood crafting (signs, plaques, and ultimately a CNC-made electric guitar)

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