omnijig question

[alex grams]

So I was setting up the 24" omnijig to do some test runs, and noticed something. This may be hard to explain, but bare with me.

Take a drawer with dovetails on all four corners. Now just imagine one side panel (tailboard or pinboard). The way the dovetail jig is set up, I would not be able to have a perfectly mirrored pattern at each end of the board. Since you have to rotate the board on the jig to route the opposite end, this would create mirrored/flipped pattern of the tails/pins. (see the attached image to help clarfiy what I am trying to say)

The only way to have a perfectly mirrored board (where A opposes A and B to B and so forth) is to make the fingers on the jig perfectly symmetric
about the axis of the piece being routed.

Does anyone else run into this or notice this? Could it lead to bigger problems? I could see on a uniquely spaced non symettric pattern you would have inverses of each other on each side of the drawer face (or you have to readjust the fingers for each pin and tailboard.

Someone let me know if I am crazy and completely off base.

[Gary Muto]

I believe you have it right. I never thought about it, but making symmetrical dovetails would be the best solution.

[Chris Rosenberger]

To get a mirrored layout on both ends of the drawer as you have it pictured. You would have to use both sides of the jig. Cut one end on the left side of the jig & the other end on the right side of the jig.
I cut all of my dovetails this way. I mark the top on all of my parts & the top edge goes against the stop on the left or right of the jig.

[alex grams]

well that would make more sense Chris. I guess I just have to flip the fingers to the opposite side each time. I presume then that the depth setting jigs are designed for this.

live n learn...

[Charles Lent]

No, you should lay out your finger pattern on one side of the jig and then place a scrap board under them. Mark both sides of each finger (the straight part) on the board. Then turn the board so that the eddge that was touching the side guide will now touch the side guide of the other end of your jig and place it under the fingers on that end of your jig. Then position the fingers to match the marks on the board. You now have both ends of the jig set up for the same pattern, but mirror image to each other.

Charley

[alex grams]

Charles,
Your idea would work as long as the piece to be cut isn't wider than 12" and you don't use more than half of the fingers for each end. Though for all normal drawer design, this would work out well. Thanks for the clarification though, as now i see that your suggestion is the same as Chris's. Where I got the notion to flip the fingers from his suggestion, I am not sure...

I did make up a drawer last night with each end of the boards being the mirrored/rotated opposite of the opposing end of the board. This worked out well enough for a symmetric (or at least visually, but not perfectly symmetric) pattern.

Another question is how exact do you all expect your joints to be in terms of the pins/dovetails protruding to be?

I am fine if they stick out a little and then just sand them even. I think the effort to make the ends perfectly flush out of the jig isn't as wisely invested as just a little sanding would do to fix the same problem. Though with more use of the jig, i will fine tune it to make these joints more even.

This is just in regards to the overhang, not the gap between the pins and tails, which is nice and snug, just enough where I can tap the joint together with a hammer, and wiggle it loose with my hands.

On a final note, I need another router. My biggest time loss is having to change the bits every time i change tail/pin boards. It would be nice to have the depth for a project set on each router and not have to change bits and readjust the bit every time I change boards...

[Greg Cole]

Alex,
I know nothing of the jig, but when I machine cut mine I use a low angle block plane to pare them down flush with the carcass.
Another little nudge from me to spend a few bucks if you don't have a decent block plane, something I seem good at....ya know that bad influence and all....:rolleyes:

Cheers.
G

[John Eaton]

I have two 690's dedicated for use only in dovetailing - one for straight, the other for dovetail bit.

-- John

[Charles Lent]

Alex,

You will find that you will have less need for 2 routers when you have built up more confidence and begin doing your dovetails in batches, making all of the pins and then all of the tails. You are only suffering right now because you are trying to make one complete joint at a time. Still, if you will only be making one or 2 joints, then 2 routers may not be a bad Idea. Most of us (for me anyway) set up and then make dovetails for a whole project at a time and this usually involves 20 or more pieces all cut with the same setup. An hour or two between bit changes makes a second router not really necessary.

Charley

[alex grams]

I ran about 6 drawers last night with the jig, doing all pinboards and then tailboards. It turned out well, but i still would like to set the bit depths in two separate routers, do a test cut on a scrap piece, then just go to town mass production style on the boards without changing back and forth on bits and hoping that the depth is perfect.

Also, it would be nice to have a router for my table and another free one for hand work.

It is taking some getting used to the tolerances on the jig, and what I can expect in terms of spacing and such.

The drawers I did up last night had about 3/32" at most overhang on the tailboards and pinboards.