Dovetail Jig for the Shopbot

[ken_rychlik]

First I have to give Gary C credit for being the pioneer. I just found a way that was cheap, easy and worked well for me.

I have had some request for info on the jig that I cut my dovetails with, so instead of replying to them, I will start a new thread here that describes what I use.

First here are a few pictures of my old jig that I used with a router and bushing guide. I will follow with more pictures and info. The side view picture is important to see what I cut off of the original unit.

[ken_rychlik]

I purchased a new jig that is a jet brand, but there are many coppies that can be purchased pretty cheap. Go to ebay and search dovetail jig and you will find plenty like this for less than 50 bucks. I bought mine for about 70 from amazon, but they don't show them in stock any more.

I cut off the back feet to where it would slide onto my table easily. Then I removed the finger guides and stops that the router uses. I then installed long bolts from the bottom and front side and tack welded them in place to hold the upper and front clamp bars.

What I am left with is a device that will hold the material off of the end of my machine for very little money invested, but it works quite well.

[ken_rychlik]

Next I drilled and tapped two holes in my cross beam where I wanted to mount the jig. Two bolts go through the jig and into the main cross beam on my 'bot. Note on the bottom view the spacers that were added in the post above this. This was necessary because the bolts that were tack welded on the bototm needed to not interfere with the way it sat on the spoilboard.

Here are pictures of the unit bolted to the bot.

[ken_rychlik]

The jig is set up to have 1/2 inch spacing on the fingers originally and I kept the way it cuts the dovetail true to the original design. I used the stops that came with it to offset the parts by 1/2 inch just like it was meant to be on the jig. This 1/2 inch offset is critical for the parts to fit.

I started out using a cheap grizzly dovetail bit, but have switched to cmt bits. It is a 9/16 14 degree bit with 1/4 inch shank.

My dust collection comes off the back of my spindle and does not work with the jig currently. I really need to make another one just for this purpose. I am showing my dust foot (home made) so you can see where this would hit the top of the jig.

[ken_rychlik]

Next I made a file that will plunge down on the right side of the part, skim cut across from right to left to prevent tear out, and then run in the same motion that the hand router did while using the old jig.

0,0 on my machine is where the spindle is sitting in the pictures. If your machine is any different these cut files won't work.

The usual warning about plug these files into your machine at your own risk apply.

The setup file changes the 0,0 position of the machine and then goes over the 1/2 inch baltic birch and pauses for you to put your zero plate there. The bit is then zeroed to the top of the material over the jig.

Different thickness material could be used and different bits as well, but I am just posting what I have working (1/2 inch baltic birch). If someone makes new files for different material and or bits, please post them for others to use.

Then there are different dovetail files for 4 thru 10 inch. I only make them in one inch increments because of the 1/2 inch offset that it is made with.

The mahcine will have to be a fixed bed machine and you will need to be able to move in a negative x about 2 inches to allow it to work as mine does.

A wood backer is used on the right side of the upright part to prevent blowout there as it has no support on the last 1/2 inch.

[ken_rychlik]

Here is a picture of the backer to prevent blowout in place.

[ken_rychlik]

The part laying flat with the table is the front and back of the drawer.

The upright piece going down off of the table is the side of the drawer.

As you put the parts in the jig, any crown in the material needs to go up on the horizontal part, and towards you on the vertical part. This will let the drawer bottom straighten them out on assembly.

As any dovetail jig goes, lower the bit to tighten the joint, raise the bit to loosen the joint.

If you are not cutting the center of the parts, adjust your zero, zero position to correct.

Feel free to fire off any questions on things I missed.

[myxpykalix]

thanks for the info and all the effort kenneth, much appreciated! I think we all have one of those cheap dovetail jig laying around somewhere....now where did i put mine??

[loriny]

Looks good Thanks for the idea and the information.
Lorin

[wberminio]

Thanks Ken

I have been outsourcing my drawer boxes for years.
Last few years,with my Bot, I have been cutting my drawer boxes out of
pre- finished plywood.I have been edge banding using butt joints-Glue and nails-
Not the best method but the most cost effective in this economy.
I shy ed away from dovetails because of the work involved with preparing the solid wood blanks
Never thought of using pre cut drawer blanks.
I will give your system a try!

[khaos]

thanks for the info and all the effort...

Indeed Kenneth, thanks so much. I have had inconsistent success on the bot with dovetails. I see how this method will lock it in.

[dlcw]

Great series of posts Kenneth!

Thank you very much for your time in putting this together. :) :)

[ken_rychlik]

I hope it helps some of you get yours working. I like the fast cam clamps that hold the wood in place and the joints are very acurate, once you dial it in.

I'm sure each machine will need to be adjusted for the files to work. To make it fit your machine after you have your jig mounted, make adjustments to your 0,0 poing on where it cuts.

After you figure your machine out, then make the adjustments on the setup file to where you can throw the jig on, and be cutting very quickly.

You can air cut the setup file to see what it does, and just zero it with a thick board for a test. Then run one of the files to see how and where it works on yours.

I didn't mention it, but it is all in american inches. I don't have any metric files.

[michael_schwartz]

Thanks for posting details of your setup

One of these days I will get around to setting up a dovetail jig for my bot.

[loriny]

Inches are fine. Our country is so closely linked with yours that we need to learn both systems. Metric is what we learm in school but the real world teaches us imperial.
Lorin