Domino alignment

[MTbassbone]

This is my first major project. I am building a pair of bookshelf speaker. Since I have never done this, I decided to build a test box first using scrap material. I am going to use baltic birch for the box, and want to use mitre cuts so the plies are not visible on the side. I figured it might be a good idea to put in a few dominos so the mitre joints don't move while the glue dries. I am having difficulty getting consistent domino mortises and am unsure of what to do. I am using the flaps for alignment and am trying to make sure everything butted up correctly. Here are some pictures.

 

[ChuckS]

Looks like the fence registration against the stock wasn't held and done consistently for the mortises, a user error seen before. Rule that out first.

 

[luvmytoolz]

Looks like maybe you're tilting or lifting the Domino when plunging.

Are you clamping the timber down properly so it's not moving when plunging?

To fix these mortises though, you can just cut some timber to glue in the holes and then re-mortise when dry.

 

[ChuckS]

Here's a jig you may look into if you try everything, and it still doesn't work:

Post in thread 'How do mitre boards with different thicknesses using a Domino?' https://festoolownersgroup.com/thre...-thicknesses-using-a-domino.73391/post-710045

 

[cdconey]

Which side of the miter are you referencing?

 

[MTbassbone]

Which side of the miter are you referencing?

The inside edge

 

[Michael Kellough]

Either the fence slipped or it’s some kind of operator error.

 

[grmaxx]

This is typical user error. Start with a lower depth setting and make sure you’ve registered the domino properly—there should be no play or obstructions. I’d begin with a thick piece first, not small pieces like the ones shown.

 

[Packard]

I had a similar problem using the fence on my Porter Cable biscuit joiner. Solved: made a platform that allowed me to bank off the base plate. Much easier to control. But only works well for sheet goods. Not for building, say a chair.

If anyone is interested, I can post a photo.

 

[bobtskutter]

Hello @MTbassbone plunging mortises in to 45degree faces isn't easy.

If you're plunging into a 90degree edge, holding the fence on the reference face and pushing away from you will lock the machine against the face you're going to make the mortise in. But this doesn't happen when you're plunging into a 45degree miter face. Pushing the grab handle away from you will make the machine slide up the 45degree face and this can make your mortises miss aligned. Try to hold the machine against the miter edge without trying to slide it away from you or tip it away from you. You need to be gentle with it.

Good luck

Bob

 

[ChuckS]

Forgot to add that you should check how accurate your miter angle was cut on the stock. If your domino fence was 45* but your stock wasn't or vice versa, there'd be a higher chance of the machine slipping away as you plunged. So check both angles on the fence and the stock before you try again.

As Bob pointed out, moderate pressure would be good enough when you hold down the machine and plunge.

To increase grip, I did this: https://festoolownersgroup.com/thre...e-domino-in-middle-of-board.24146/post-574929

 

[MTbassbone]

I tried again today. I started by squaring up the fence on the MFT. My boards were square within about 1/32 to 1/16". Is the good enough or can I get better? Then I tried putting two dominos in and used the flaps from each edge. One corner looks good and the other not so much. Prior to using the domino I adjusted the levers so I could tighten then down more. The 1st picture has an arrow where the mitre starts to skew away from being correct. It gets worse going right from the arrow. Any hive mind knowledge is appreciated. The mitre joints fit together fine without the dominos so it has to be my technique with the DF500.

 

[bobtskutter]

That looks like a huge improvement to me, well done!!
You've got to make 4 plunges to fit the two dominos, you've only got to get one plunge slightly misaligned for that to happen. Meaning you must be 100% perfect every time, that's not easy.
Keep practicing, you'll get it.

Bob

 

[MTbassbone]

would the dowelmax be the better tool for the job? or maybe just skip the dominos altogether? maybe just glue and tape?

 

[Michael Kellough]

First make a mitered joint with just glue and tape to confirm your cutting is right on.

While the mitered joint is drying try butt joining two pieces of wood to test your Domino technique.

 

[Packard]

would the dowelmax be the better tool for the job? or maybe just skip the dominos altogether? maybe just glue and tape?

Plywood miter joints are underrated for strength. If you have a 3/4” thick board, 1/2 of the glue surface (just over one inch total) will ne edge grain to edge grain, but the other half (just over 1/2”) will be face grain to face grain.

So a 1/2” to 1/2” face grain glue joint. If that is not strong enough, add a interior gusset running the length of the joint.

Here is an image of a plywood miter joint. You are looking at the end grain on the darker bands. At the glue joint, those same bands will be face grain to face grain.

 

[ChuckS]

would the dowelmax be the better tool for the job? or maybe just skip the dominos altogether? maybe just glue and tape?

Unless your DF is a lemon, it'd be a shame that it is excluded from doing mitres and bevels. The fence with its angle feature is designed for handling not just right-angled joinery.

 

[cdconey]

It's looking better. It takes a little while to get the hang of dominos on miters. Are you referencing from the outside face? That should give you a more consistent reference and less chance of the DF walking a little bit when starting to plunge.