My domino joints move

[Michael Kellough]

"I do have some difficulty balancing this XL on narrow stock."

If the machine moves at all during the mortising plunge, it will excavate an oversized hole. If you are trying to balance it on narrow stock, and you succeed in keeping it lined up with your registration mark but it does tip down a little, then the hole will be too tall at the point where the tipping occurred and the Domino will wiggle up and down at that point even if it is tight from side to side.

It may be that the XL machine is too big for your purpose.
The less experience you have keeping it still the bigger the stock needs to be.

 

[frigator]

Once again, thanks for all the suggestions and advice. I spent the afternoon practicing using two Dominos per joint. Seems there's less wiggle using two  dominoes versus one.  My  next projects going to involve me joining  8/4 and 5/4 stock with the work pieces 2 3/4 and 2 1/2 inches wide.  So I don't know if that qualifies as narrow stock or not.  There is definitely less slop with two dominoes than one. Also found that if I go deeper than 25 mm I can't get the domino back out probably 1/3 of the time. At least not without pliers. So I'm thinking maybe my mortises arent too wide after all????  Perhaps a small degree of slop is just present in the domino joint. Could also be a difference in smooth vs ridged tenons. With the smooth walled FMT tenons I get no slop. Perhaps the ridges allow for some movement.

I've had all my calibers out measuring the dominoes and the mortise and there seems to be about a 1/10 mm difference or less in the sides. And the dominoes vary up to 1/10 of a millimeter themselves. Does that seem about right?I only need to tap if I'm going deeper than 25 mm.  I am not going to have time to get back to woodcraft this afternoon so I may miss my 30 day window return.

 

[grbmds]

After reading all of your posts, I'm not sure what you consider "slop". In all of my projects the dominos fit into the slots tight with nothing that I would call slop. Most of the time I have difficulty pulling them back out by hand when I dry fit pieces together. In fact, one of the reasons I generally use dominos when edge gluing panels to make wider panels is because the domino fit is so good that the glue joint requires little or no leveling either by sanding or planer. That is what I expect out of the Domino. While there have been rare situations where the fit isn't that tight, they are truly rare and usually are the result of something I did or didn't do when I cut the slots, such as pushing down on the back of the tool too much which resulted in the front lifting up slightly.

One thing I would ask is . . . Are you plunging in the same slot a second time in an effort to clean up the edges? That could cause the domino to fit more loosely because it is unlikely you could plunge exactly the same twice in a row. In using the FMT, I would always route the tenons and mortises a second time after completion to be sure they were clean. The Domino does not require that.  Since that never came up, I thought I'd just put it out there as a possible cause.

 

[ChuckM]

A tight fit of the Dominos is fine and actually good in the final assembly stage. For dry-fitting, it could be a pain; my solution is always to microwave them for 15 to 20 seconds, depending on how many of them is cooked at one time.

I put them on a coffee filter in the microwave and you can tell the moisture that gets "squeezed out" on the paper when you take them out.

Sanding, planing or chiselling the edges is a lot of work if you have 50 or 60 mortises cut. My method works like a charm, every time.

Chuck