Finger (Box) Joint Jig for Zen 7x12

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Finger (Box) Joint Jig for Zen 7x12

Postby Sparky » Sat Nov 19, 2011 3:16 am

This is a simple finger joint jig that can cut pieces up to 5" widths (due to the space between the Y axis guide rod and leadscrew) on the 7x12 model. The length is only restricted by the height above the floor, so that even large drawers could be produced.
I've made several boxes on the table saw, but find the CNC method much more accurate and easy to use after a little practice.
Dimensions are given for the MDF table (horizontal piece), but the existing PVC table can be used as a drilling guide for the mounting screw holes.
The "footprint" of the MDF table is smaller than the original to allow for better workpiece clearance and to allow its entire surface to be milled flat. In my haste I overlooked the need to make the vertical piece easily removable so that the router can be used for conventional milling without cumbersome setup and disassembly. That will be the first modification to the jig. It should go without saying that this is presented in the spirit of DIY sharing and that there are many, arguably better ways to accomplish the same result. Obviously, this simple concept could be applied to other platforms.
ZenFingerJointJigA.jpg

BoxJig2.jpg
Tool path is generated in CorelDraw and Cut2D.
Piece to be cut is placed against backer board, with right edge against the stop and clamped into place. To prevent tear out when the end mill exits the workpiece, clamp a sacrificial piece against the face.
BoxJig3.jpg

Since the router must be positioned beyond the front edge of the workbench to allow clearance for the workpiece, be sure to clamp the frame down so it doesn't tip over.
BoxJig1.jpg

While not quite as strong as the box or finger joint, the jig can also be used to produce more decorative "through dovetail" joints with straight, non-rounded corners. Mating pieces are cut on edge using a dovetail bit and an end mill.
Dovetail4.jpg

Rockler has a 1/8" shank dovetail bit, item no. 23082
http://www.rockler.com/product.cfm?page=21321
Grizzly also has a 1/8" shank dovetail bit
http://www.grizzly.com/products/Dovetail-Carbide-1-8-Shank/C1792

Updated 11/28/2011
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Re: Finger (Box) Joint Jig for Zen 7x12

Postby bader357 » Sat Nov 19, 2011 10:55 am

Looks good and it is a very good Idea.
So, the ZEN machine become more flexible for different work.
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Re: Finger (Box) Joint Jig for Zen 7x12

Postby Xin » Sat Nov 19, 2011 12:16 pm

I have been waiting for this kind of demo for so long. Well done, Sparky. Dovetail next? ;)

By the way, you can turn the gantry backward and turn the base upside down to get more clearance under Z. But in that case, you will need a second machine setup for normal operations.

Thank you so much


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Re: Finger (Box) Joint Jig for Zen 7x12

Postby Sparky » Sat Nov 19, 2011 12:27 pm

Xin wrote:I have been waiting for this kind of demo for so long. Well done, Sparky. Dovetail next? ;)

Thank you so much

Xin

Thanks Xin! ESP must be working. . . it just occurred to me that this jig could also be used for dovetail cuts with the appropriate toolpath and planning. I'll give it a try, hopefully soon, and post results.

Xin wrote:By the way, you can turn the gantry backward and turn the base upside down to get more clearance under Z. But in that case, you will need a second machine setup for normal operations.

Just a thought.

Xin


Wow, now that's some thinking outside the box! Great idea!
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Re: Finger (Box) Joint Jig for Zen 7x12

Postby Xin » Sat Nov 19, 2011 12:34 pm

The only issue I was trying to figure out was the little round corner on dovetails, either use a dovetail chisel to clean up after the machining, or let people get use to it. :lol: Any CAM software that can do inlay will help. Did you also make the box top decoration on Zen machine?

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Re: Finger (Box) Joint Jig for Zen 7x12

Postby Sparky » Sat Nov 19, 2011 5:00 pm

Xin wrote:The only issue I was trying to figure out was the little round corner on dovetails, either use a dovetail chisel to clean up after the machining, or let people get use to it. :lol: Any CAM software that can do inlay will help. Did you also make the box top decoration on Zen machine?

Xin


You're right of course. The sockets of "through dovetails" could be cut on this jig, but not the pins which would have rounded inside corners if cut flat and vertical sides if cut on edge. Pity. We need another axis.
ThroughDovetail.png
ThroughDovetail.png (17.38 KiB) Viewed 12227 times

The Celtic knotwork on the oak box was created with a Windows font available from http://www.clanbadge.com. I had to trace it in CorelDraw to create a single line toolpath. I then filled the groove with an engraver's crayon, but am still experimenting with other methods.
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Re: Finger (Box) Joint Jig for Zen 7x12

Postby Xin » Sun Nov 20, 2011 12:20 am

Another axis probably wont solve this problem, I have tried a dovetail bit (14 degree) with a palm router. The trick is to find a good feedrate and router rpm combination to make the cut clean and without burn.

Back to finger join, we really can make any crazy pattern with ZEN machine, not necessary to be equally spaced. If someone here kind enough to create a parameter driven g-code generator for finger joint cut, it will sweet, isn't it.

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Re: Finger (Box) Joint Jig for Zen 7x12

Postby Sparky » Sat Nov 26, 2011 3:14 am

Updated original post to include a method of producing "through dovetail" joints.
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