Sharing Carbide Create Dovetail Files

(William Adams (Carbide 3D)) #9

Actually, it’s been a long time since geometry in high school.

Instead, it’s more straight-forward to just draw this up — we start with the endmill itself since it and the stock dimensions as discussed above are the fundamental constraints.

Since the dovetail bit we have selected can only cut to a depth of 1/2", we have to leave 1/4" uncut for the blind dovetails, and we have to determine if we will draw up the pins or tails first. Folks do it both ways, and there are numerous arguments for tails first:

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New Threaded 90 Degree Table for my Shapeoko 3
Chippendale (Newport RI) Desk Legs
(William Adams (Carbide 3D)) #10

We’ll do tails first since that is the board which is held vertically and a bit easier to visualize.

The next consideration is how many pins / tails there will be — as noted, we are constrained by the endmill geometry in a way that we are not when cutting by hand, so the tails have to be greater than 0.5" at their largest dimension, and must be at least 0.25" at the base. With a 5" tall box, we will simplify this and have 5 tails/pins, with a half pin at the top and bottom.

One way to do this visually is to draw up a side view of the tails, evenly arrange the tips and then use the drawn up tool to line things up:

With that done, we can begin to draw in boxes to represent what will be cut and what will be left behind.

One has to consider that one will be working with a 1/4" endmill which will be cutting from the center out in Carbide Create, but the actual path ultimately will be the dovetail bit which will cut a 1/2" diameter at the bottom. We will need to leave clearance at blind side to ensure the dovetail bit doesn’t blow out, and overcut on the other to ensure that we will have a clean, square cut of the sides of the tail — drawing in some circles will help to visualize this:

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(William Adams (Carbide 3D)) #11

This results in the following areas which need to be cut from the end of the board to make the tails:

Probably it would be best to make two cuts, one with a square endmill to clear the center, then a second cut as an inside contour pass with the dovetail bit — note that it will be necessary to work up the path so that it plunges from a point where it will not remove material which needs to be preserved.

(This is why it was originally noted that Carbide Create can’t directly do this — one will either need to edit the G-Code by hand or work up the orientation of the geometry so as to ensure that there are no such difficulties)

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(Jed) #12

WillAdams this is some awesome work you have done do you have a copy of the carbide create file? I am confident if you provide the file I can do some additional work on top of the great stuff that you have done. What is the best way to upload the file to the forum. I am sure others will benefit from this too.

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(William Adams (Carbide 3D)) #13

If you follow along you should be able to make your own Carbide Create file.

For the pins, just add some circles to help envision how the toolpath should work:

Then go back and adjust paths as needed for:

  • cuts w/ a 1/4" endmill to clear the pockets to the depth of the cut
  • clearance for the endmill when making the pockets
  • draw in paths for the dovetail bit to cut along a no offset contour path
  • then verify that things will fit together
  • then arrange the paths in Carbide Create to cut the pair with the tails being cut out of the board held vertically and the pins cut out of the board held in place on the machine
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(William Adams (Carbide 3D)) #14

Drawing in the toolpaths, one can verify them by assigning suitable strokes:

Adjust slightly to not have overlapping paths:

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(William Adams (Carbide 3D)) #15

Arrange things so that you’ll be able to cut the pins on the horizontal board on the machine, and clamp the board for the tails to the front:

dovetails

Import that into Carbide Create and adjust the size to scale and set things to a centered origin:

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(William Adams (Carbide 3D)) #16

Set the origin to the center of the stock and align the corner of the board against it. Adjust the pockets and cut them to the desired depth using a suitable endmill, then set up a different tool for the dovetail bit and assign a toolpath which has a depth per pass sufficient to ensure that only one pass will be made.

dovetails.c2d (155.5 KB)

EDIT: Sleeping on it, I believe the board which is held vertically needs to have its toolpaths adjusted — they need to be cut all the way through — it’ll also need to be shorter by twice the blind depth left in the other board.

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(William Adams (Carbide 3D)) #17

Just for compleatness’ sake, there are a couple of commercial software programs which address this sort of thing. You may want to consider:

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(Jed) #18

Hi William
I just ordered the software from tailmaker. it seems like it will do the trick. I will test it out this weekend and keep you posted. Thanks so much for all you EXCELLENT assistance.

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(mark robinson) #19

keep us posted please :slight_smile: looks really cool

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(William Adams (Carbide 3D)) #20

Glad the commercial software looks suitable for you — I’ve been considering being one (or both) of those myself.

In the meanwhile, turns out that there are a couple of options for 3D modeling these in OpenSCAD:

So I’m going to revisit 3D modeling and sort out simultaneously modeling and drawing these up so that we can get paths cut.

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(William Adams (Carbide 3D)) #21

Okay, making progress on the 3D modeling (w/ some help from the OpenSCAD mailing list/forum):

EDIT: Subtracting one from the other is easy — now I need to work out the toolpaths / geometry to make that as an actual cut.

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(Neil Ferreri) #22

Did you ever try this out?

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(William Adams (Carbide 3D)) #23

In Camotics it’s possible to enter a dovetail bit as a stub endmill:

image

which then allows one to preview how the file will cut:

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(William Adams (Carbide 3D)) #24

I believe it’d be helpful to have a jig to ensure that the parts are lined up accurately:

dovetail_fixture.c2d (132.1 KB)

Though I’ve been using it only to line things up to clamp for the cut:

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CNC Finger Joint Box
(William Adams (Carbide 3D)) #25

Workholding gave way for the next to the last cut, and didn’t quite get things lined up on the last, but at least this proves the concept:

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(Jeff Peters) #26

Will I downloaded the dovetail file and when I click on to it opens the connect to cutter .
So what am I doing wrong
Jeff

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(William Adams (Carbide 3D)) #27

You would want to open:

http://community.carbide3d.com/uploads/default/original/2X/9/9361326a9e42c5318b00fb18a75ccfe8c7165743.c2d

in Carbide Create and make toolpaths suited to your machine — hang on though, I’ve got a generalized fixture which I’ll be posting (along w/ a hardware list and photos showing it in use) which should work better.

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(system) closed #28

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