First dovetail problems

[skeeter]

Finally built up enough nerve to attempt dovetailing some drawers for a project for LOML.

I'm using a PC router with D handle and a 14 degree dovetail bit on a Rockler dovetail jig. Spacing and depth are great. My problem is that the dovetails are too tight. I have to hit them really hard to drive them together, hard enough I'm afraid I'll split the wood. Can anyone explain to a first timer how to make correct adjustments for a better fit??

Thanks!
cg

 

[FredP]

raise or lower the bit just a bit and try some scrap. one way tightens em and the other way loosens em. [I think you need to raise it some ] I can never remember what wat to go.:gar-Cr

note: the scrap must be the same thickness as the project pieces

 

[CDPeters]

I'm pretty sure Fred's right - raise to loosen - and it don't take much!

C.

 

[Joe Scharle]

Too tight?
Lose height!

 

[rsaucedo]

I have the same dovetail jig and also use a PC router. I found that the bushing that comes with the kit or the router base were a little tiny bit out of round.

Believe it or not I turned the router 180 degrees and went over the dovetails again and the joint was looser. Wierd but my dovetails fit....:dontknow: did it every time after that and all joints fit well.

 

[JimD]

I use a different jig, a HF, but I had the same problem recently. I assembled the drawers by trimming a little off the outside pins so they would not split the oak drawer front and used a 4 lb dead blow to assemble the drawers. Works but a bit crude.

The next drawers I reduced the bit height a tiny bit (easy with a PC by a slight rotation). I want them tight enough I have to use a mallet for assembly but not so tight I have to trim the pins to avoid splitting. I also prefer to use the 1 lb dead blow (and a block of wood so the blow goes all the way across the joint).

It is best to keep the router in about the same position for all the joints because of the point brought up by the post above. The bit and guide are not always perfectly concentric but it doesn't seem to hurt much as long as you do not rotate the router while cutting. Rotating it messes up holding the router, at least for me, so it's better not to rotate for other reasons.

Jim

 

[Charles Lent]

You must keep the router bushing perfectly centered to the router bit/collet, or you must always keep your router oriented the same way with respect to the dovetail jig. This is true for any brand of dovetail jig that uses guide bushings in the router to guide it through the jig.

I put an arrow on the top of the base of the routers that I use for dovetailing and point this arrow toward the jig every time that I am cutting dovetails. This is so critical that I do both to make certain that my dovetails are cut correctly. I use DeWalt 618 routers and they come with a centering tool to center both router bases and bushings to the collets. These centering tools are also available for sale if your router didn't come with one. It consists of a precision ground shaft that fits in the collet and a plastic cone that fits tightly on the shaft. With the shaft inserted and tightened in the collet, you place the cone on it and press it into the hole of the base or bushing and hold it while you tighten the base mounting screws or the bushing nut. The bushing nut needs to be very tight, as a loose bushing will ruin your dovetail cutting accuracy.

When you change the bit depth to adjust for the tightness of your dovetails, make only very small changes to the dovetail bit height setting and then make test cuts to see if it is correct. Once you have it correct, measure the bit height to the router base with a precision caliper and record the measurement somewhere safe just case you ever need to make additional identical dovetails. If you have this measurement (in thousandths of an inch) you can remove and replace the bit and return to the exact setting, but be careful since a different bit of the same size may not use the same depth setting.

Charley

 

[skeeter]

Much better results this morning. Thanks for all the help!

 

[Joe Scharle]

That's a great feeling, isn't it? Here's a couple of things for future reference, in case you don't already know.

Too tight?
Lose height

PINS on (4 letters)
ENDS ( drawers and boxes have a front END and a back END)

TAILS on (5 letters)
SIDES

And on half blind jigs:
TAILS hang down like a PONY

My HF jig is still my goto jig for quick half blinds even though I have a Woodrat, and have owned/used many expensive jigs over the years...IMHO

 

[JimD]

I use a Grizzly template guide on my HF dovetail jig and it works very well for me.

I reference a very old Woodsmith article for making adjustments - when I decide to adjust instead of finding a bigger hammer.

I made a U shaped jig of 3/4 plywood with a drywall screw in the center a long time ago. The screw is adjusted such that the dovetail jig should either touch (very tight) or almost touch to be tight but not big hammer tight. Now if I just remembered that... I wrote notes on the jig but it seem like the wood may also make a slight difference - or maybe it is wear in the bit.

Jim