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Forum topic by JAAune posted 05-01-2014 06:25 AM 1544 views 0 times favorited 9 replies Add to Favorites Watch
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JAAune

971 posts in 1065 days


05-01-2014 06:25 AM

I was recently asked how we utilize the CNC in our furniture shop and what software strategies are used for some of the more unusual applications (non-panel work). Rather than reply directly to the questioner by email I chose to create a post here so others can enjoy the information.

Of course we do process sheet goods frequently. For cabinet jobs we’ll rout horizontal grooves for shelving and vertical grooves for shelf standards.

Without a vacuum table or nesting software we don’t get huge time-savings here but it’s still useful when we have larger panels or lots of them. Nothing exciting or unusual here and I’d guess most people think of this kind of work when they think about CNC routers.

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I’m sure nearly every CNC owner knows this one but those who don’t have a CNC may not realize that it is the perfect tool to make jigs that will be used for traditional woodworking techniques.

Those parts will get glued together to make a steam-bending form.

Since the bending strap is saved as a 3d model, it is easy to get all the parts sized perfectly before cutting everything at once on the CNC.

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If you can find a pen with a barrel a little less than 1/2” diameter that has a spring loaded tip, a few wraps of masking tape will allow it to fit into the router collet.

Instant 48”x96” plotter. That cheap pen setup won’t hold perfect tolerance but it does a fine job making patterns in most situations. Just make sure the spindle is turned off before doing this!

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Going back to panel work, nobody said the panels have to be plywood.

Here the router cuts the final shape into a glued-up assembly of oak boards. Everything was built slightly over-sized. The CNC cut the final shape, then proceeded cut rabbets for the triangular panel openings.

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The machine is also our go-to tool for odd pieces of molding.

That’s over 6” wide and we only needed three pieces so custom molding cutters were out of the question. The opening in the middle will accept a piece of purchased, carved molding.

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That piece of curved molding would have cost us $250 to purchase and the project had already gone over budget.

The blank for the molding was glued to plywood with paper between the oak and the plywood. It held fine for machining but came off easily enough when I tapped a chisel between the two parts.

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This is basically molding except after the profile is shaped, the machine comes back and cuts the shapes for bracket feet. It also cuts grooves to mark where we will later make miter cuts to get our four parts.

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Everyone knows CNC can do carving but how does one get the 3D model for custom designs that look as good as high-reliefe hand-carvings without expensive software or 3d scanners?

The answer is I didn’t. Instead I just did the rough setting-in work and used the pen to draw the pattern on the shield. The rest gets done by hand. Once the carving is finished I will try a special, 4-shot photography technique that can be used to generate a high-contrast photograph for use in CAM software that works on pictures.

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If the CNC will run the spindle at a low enough speed, some metal work is possible too.

This bit of brass is a lid stay that moves in increments of 5 or 10 degrees. Each tooth had to be shaped and positioned exactly so CNC was the natural choice to make the part.

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Here are the finished projects.

It features steam bend walnut trim (CNC cut bending forms) and hand painted crest and scroll. The painter charged us less because we provided perfect CNC-drawn patterns for her to paint over.

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Here we have another example of steam-bent components bent around CNC-cut forms. All of the crown was milled on CNC. Normally the straight portion would have been purchased except getting molding over 12’ long can be expensive. The cabinet sides were all grooved on the CNC for shelves and shelf standards. The top piece of plywood was cut to its curved shape on CNC then slots and holes were cut out for the lighting to get a tight fit for the fixtures.

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Face frame and large moldings are CNC cut. The carved portion was purchased however since we wanted the hand-carved look and not a machined surface.

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This is where those CNC-cut bracket feet and the custom lid stay ended up. The dark openings in the corner blocks were also done on CNC then dark veneers were glued inside.

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What’s the special software that makes the above possible?

It’s just good, old Sketchup. Since I model everything before we start a project in our studio it’s not much more work to transfer portions of the drawing into CAM software.

There’s the portion of the missal stand ready for export into CAM. That’s a good example of the combination of solid models and 2d drawings I often use to do my work. Sketchup has a plugin available that will export the solid as an stl and the lines as a dxf so it’s not necessary to own the pro version.

The CAM software is just BobCad so nothing fancy. We were offered a good price on it when we built our machine and that’s what I learned to use in the class.

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So that’s a pretty good overview of what goes on in our shop CNC-wise. I’ve answered the question I received by email which was my original motivation for making this post. If anyone else wishes to share their own CNC projects and work techniques feel free to jump in and post.

-- See my work at http://remmertstudios.com and http://altaredesign.com


9 replies so far

View dannelson's profile

dannelson

151 posts in 1119 days


#1 posted 05-01-2014 11:31 PM

Is the curved crown a 3d or a 2d profile? Care to share the file?

-- nelson woodcrafters

View JAAune's profile

JAAune

971 posts in 1065 days


#2 posted 05-02-2014 12:11 AM

I have both. I started with the 2d profile then extruded it around the desired curve to create a solid in Sketchup. The CAM work was done using the solid model.

Which do you prefer? I can give you a Sketchup file or a 2d dxf or 3d stl file.

-- See my work at http://remmertstudios.com and http://altaredesign.com

View dannelson's profile

dannelson

151 posts in 1119 days


#3 posted 05-02-2014 02:14 AM

Guess I should have been more clear,when you toolpathed the profile was it a 3d or a 2d strategy ?as far as file format it doesn’t matter I can use both. I have extruded curved crown profiles in the past but have only been able to cut them in 3d I was just looking for a faster way. Maybe mill the coves with a bowl bit or balled end mill 2d and the rest 3d thanks Dan

-- nelson woodcrafters

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JAAune

971 posts in 1065 days


#4 posted 05-02-2014 02:46 AM

The CAM toolpathing used a 3D model for most of the profile. To speed things up though, I did the hogging with a 1/2” upcut spiral and used 2d toolpathing to do the flat edges at the bottom and near the top. The ball cutter was only used for final cleanup.

If you don’t have BobCad, I doubt you’ll be able to see the toolpathing because exporting to any other file type will likely just output geometry. I will see if I can get it packaged up over the weekend and upload it to a file server.

You’ll also want to be careful about using the CAM settings in that file even if you do have BobCad. It’s one of my earlier programs and I think the speed and depth settings weren’t quite right and I did on-the-fly adjustments at the machine to compensate. It was cutting too fast and too deep for my machine.

-- See my work at http://remmertstudios.com and http://altaredesign.com

View DS's profile

DS

2132 posts in 1168 days


#5 posted 05-03-2014 09:37 AM

JAAune, that was a very well presented post. It gives a fairly concise overview of the process you follow and the role the cnc machine plays in that process. I had never thought of mounting a pen in the collet for transferring a pattern before. I might have to try that.

-- "Hard work is not defined by the difficulty of the task as much as a person's desire to perform it.", DS251

View oldnovice's profile

oldnovice

3868 posts in 2116 days


#6 posted 05-03-2014 05:08 PM

JAAune, this is an impressive CNC post!

-- "I never met a board I didn't like!"

View Jerry's profile

Jerry

2246 posts in 2295 days


#7 posted 05-03-2014 07:07 PM

Very impressive. Job well done as they would say in the Navy…

-- Jerry Nettrour, San Antonio, www.topqualitycabinets.net

View JAAune's profile

JAAune

971 posts in 1065 days


#8 posted 05-04-2014 07:49 PM

Glad to see people enjoyed it.

I’ve got a few more pictures pertaining to this topic which I’ll soon post. They relate to that “4-shot” photography technique mentioned earlier which I intend to test out.

-- See my work at http://remmertstudios.com and http://altaredesign.com

View JAAune's profile

JAAune

971 posts in 1065 days


#9 posted 05-06-2014 02:43 AM

Here are the CAD files requested by Dannelson. The link should be good for five days or so.

CAD Files for Curved Molding

-- See my work at http://remmertstudios.com and http://altaredesign.com

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