Dovetails in MakerCrate Video

[lepton]

ShopBotTools recently posted the MakerCrate video on YouTube:
http://www.youtube.com/watch?v=Fuh4rkmoaQw

I'm interested in the technique for cutting the dog-boned dovetails from flat stock using a straight cutting bit WITHOUT using any sort of right angle jig.

Cutting the tails with a straight bit, dog-boning the corners, is the easy part.

It appears that the slope of the pins are cut using a 3D profiling technique with either a profiled dog-bone or drilled hole used for corner relief.

My question is about how the toolpaths were created. Is this type of dovetailing a standard part of PartWorks/Vectric/Aspire?

I can see how you can do this with MasterCAM or other high end CAM package but I'm hoping there is a solution for those of us without deep pockets ;)


Thanks,
-paul

[bill.young]

Those 3d moves are created with a post-postprocessor that I created a while back with my buddy Robert Bridges. The Readers Digest version is that you draw lines in VCarvePro to show the location and direction of the dovetails, create a toolpath for just them, and then run that toolpath through a small program that creates a file with all the 3d moves. It's kind of kludgy but works well.

The interesting thing about them is that since you are using a straight bit to cut them you are not limited to a particular angle like a regular dovetail bit. It lets you do things like create puzzle boxes with different angled dovetails all around, so that it only goes together one way. There's a model of a bank I've made like that in the Sketchup 3d warehouse:

http://sketchup.google.com/3dwarehouse/details?mid=1251c7027ff926ff8833b2853b56f1ad

The files to create the Maker Crates are available from Github:

https://github.com/wlyoung/Maker_Crate

and they include the "Edgetailer" program that does that post-postprocessing, and some VERY rudimentary instructions for using it.

It works well enough for me but is certainly not as easy as it ought to be. The good news is that there's some interest in creating a VCarvePro gadget to make it cleaner and simpler. Hopefully that will happen before too long, but in the meanwhile feel free to play with the Github download.

Bill

[lepton]

Bill -
Very helpful information - I will have a look and see what I can figure out.

Thanks for the quick response!

[WMNH]

Really? I thought it was just a box joint type cut not an actual dovetail. I'll have to do some more investigating. Can't quite see it in the video, is there anwhere else to see a closeup of this joint? I'll also check the links in post #2.

[bill.young]

There are a few pictures of sample parts on Flickr:

http://www.flickr.com/photos/seaside5592/sets/72157624275444318/

[WMNH]

Thanks, still trying to wrap my head around this concept of cutting dovetails with a straight bit without cutting one board on it's edge. I couldn't download the edgetailer, I'll have to try it again.

[bill.young]

Github is definitely not the easiest thing to use. If you go to the https://github.com/wlyoung/Maker_Crate page you'll see a button at the bottom of the right hand side that says "Download ZIP". Clicking that will give you all the files in the Maker Crate repository, including the Edgetailer software.

[WMNH]

Thanks! I'll try that.

[scottp55]

Bill, Up here in Limestone, Maine in person for one more day. First hand look at box yesterday. Beautiful and box is sturdier than the old wood framed shop!:) You can feel the floor vibrate when the Desktop does it's Watusi in fast VCarve. That box is tight and looks good. Thanks No movement in box at all- RUGGED.:)

[Bob Eustace]

Doesnt this box give you goose bumps??? Who else but Shopbot would go to all this trouble for their customers?

[scottp55]

It's even better in person, so solid it's not funny. Just put wheelchair parts in van at -10F up here. They lost money on the deal-and NO-Never dealt with another company like them! they bent over backwards for us. Absolutely made the right choice for the two machines! It's more than just the price and features you have to compare.:) Kudos TJ and Bill!

[lepton]

I made up a sample file over the weekend and ran it through EdgeTailer.
Converted .sbp output to gcode to run through the simulator.

http://www.lepton.com/et/pins.png

I'll be on the ShopBot tomorrow to turn these bits into atoms!

One clarification - the angle parameter in EdgeTailer is not the included angle of the wood but degrees off vertical. That is the 'air' portion of the angle.

http://www.lepton.com/et/et-ui.png

In my case the tails have an included angle of 55.52 degrees
http://www.lepton.com/et/angle.png

I needed to put 34.48 in the angles parameter to get the desired result.

Good Stuff and thanks again Bill!

[bill.young]

That's very cool...let me know how it turns out!

[robtown]

I was looking play with the underlying code... but it's just the exe.

Would you be interested in letting us fork with your code a bit?

[bill.young]

Hey Rob,

If I can get it cleaned up so that it's usable I'll put it up. It's old VB6 code that I just put together for my own use so has no comments...basically just good enough to do what I needed. Definitely not clean enough for public consumption in its current state

It may be easier for me to just extract the math behind it and post that...let me see what I can do.

[lepton]

Bob-
The angles surfaces were a bit 'fuzzy' but with a little sanding things worked really well for my first attempt.
I had the material thickness wrong by 0.014 and it is noticeable.

Bit used was a Whiteside UD2102
10,000 RPM
1.5"/sec cut
0.5"/sec plunge
Cut single pass with depth of 0.39"

Closeups of the joint for those interested:

http://www.lepton.com/et/3.jpg http://www.lepton.com/et/4.jpg http://www.lepton.com/et/5.jpg http://www.lepton.com/et/6.jpg

[Billions]

It takes a second to really understand how special this is. Great job.

Hopefully that VCarvePro gadget you're talking about comes around soon. That would be amazing to easily add dovetails like this to projects.

Again, great job!

[EricSchimel]

So the gadget is here:

http://gadgets.vectric.com/dovetail.html

I'm about to make a couple of these maker crates out of some rough plywood (I'm using them to ship stuff)

Does anyone have a sense to the tolerance? Since I'll be using the Vectric Gadget do I have to account for clearance?

To use the terminology in the gadget should my "pins" (or the parts that don't have the special angle in them) be slightly narrower than the female part of the dovetails (the part with the angle in them) so that I can get an easy fit?

These creates are going to be screwed together too, so I really want the dovetails for the stability in one direction, the screws will keep them engaged.

[adrianm]

I made a few of the dovetails when testing the gadget. It's best to make some test samples first as, with most jobs, the tolerance of fit depends on many factors such as the material, sharpness of the bit, feed rates, even humidity with some materials. The gadget itself has a cut allowance that can be set so there's no need to adjust the vectors.

[EricSchimel]

I just knocked out two crates. I used some cheap 23/32 sheathing plywood from HD and it worked great. I did .04 for my clearance. I could have gone a bit tighter, but it worked great. I shot a few screws to hold everything together and I've now got a rugged shipping crate!

If I was making a nice plywood box for someone I'd definitely experiment with a tighter tolerance.

24964

[scottp55]

Good Job Eric!:)
STILL haven't used the Gadget, even though I appreciate Bill's Joints every day!:(
12" support sections are still holding my shelf after months of leaning on it and Yarding it around.:)
Have you thought about doing the dovetails in 1/2"Ply like Bill and TJ did and then T-nutting?
Drill/driver and a couple minutes and sides/tops come right off. Extra rigidity also:)
Super easy to knock down and assemble--got this one flat packed UPS and saved me $175 shipping from NC.
scott