Matchfit dado clamps - issue with the dado groove in a workb

[fhahnel]

Just bought the Matchfit dado clamps. Milled a groove into workbench top.

My router guide is only 30" long, so I had to set up twice to make one groove. The first dado groove is perfect, the second is to tight for the clamp to slide in w/o force. Since this the very first time using a dado bit, what did I do wrong ?

Fred

[Gene Howe]

Sounds like the bit may have slipped in the collet or, you inadvertently changed the depth setting. Is your second groove a hair deeper?

[reible]

For cutting sliding dovetails in most cases I like to use a straight bit and one or two passes to clean out the channel before I come back with the dovetail bit. The straight bit needs to be sized to the narrow end of the dovetail bit and the final depth of cut of the straight bit should be as deep as you plan to go.

In this case the dovetail slot is either too deep or too shallow. Check the side that fits and then one that doesn't, if you are lucky then the cut was too shallow but only by a small amount and a second pass at the right depth will fix it.

If it turns out you can't fix it then use a straight bit and take out that whole section and make a replacement wood strip to glue in and then cut the dovetail in that. The piece should be about a 1/2" wider and a 1/4" deeper then the damaged slot.

As was mentioned make sure the bit is clean, new bits often have a coating on them and this needs to be clean off. The router collets also need to be cleaned from time to time and especially if it has had a coated bit put in it. When clean and snugged up the bit should not move. The other problem can be with the router, sears use to sell a self adjusting one...... but again you need to make sure the height adjustment is tight, you are going for no movement.

Ed

[fhahnel]

Thanks for the quick replies. When I get back into the shop, I will check this out.

Ed - In the packaging for the dovetail clamps they recommended the same process you outlined.

-Fred