Problem Lining up Dominos

[fRED mCnEILL]

I am trying to build a box using dominos and am having trouble getting the pieces lined up.

When I make a mark for the cut into the edge of the board the center of the cut lines up perfectly with the mark I have made i.e. the cut is perfectly centered on the mark. However when I make the correcsponding plunge into the face of the correcsponding board the cut is not centered on the mark. It is offset by about 2 mm.

I am using a shop made "dominplate" and a 4 mm cutter. I realize the markings on the fence are adjustable but the "scores" on the bottom of the domino are not. Am I doing something wrong? It has been suggested that I use the wider plung cut to allow for some adjustment and this does work but it just seems to me that this machine should be able to be accurate enough to use the narrower cut and have everything line up.

[Bill Neely]

Fred, I use the alignment pins to make tight first cuts on the edge and adjacent face, then widen the cuts for the rest of the mortises. I actually make tight cuts all along one side or the other because I think it makes the whole thing easier to glue up.

It isn't within my abilities to mark and make a line of completely accurate mortises, just the width of one pencil line could throw the whole thing out of whack. My experience with the cross stop has been the same - one mortise out of place (a little sawdust or whatever) and everything is out of line. I used it once when I first got my Domino and haven't even looked at it in years.

[Sam Murdoch]

2mm is too much misalignment. If you start by clamping your two pieces together and then make your marks with a sharp pencil along a short straight edge you should be able to align your Domino center line with each pencil mark and get perfect alignment. Your plunge needs to be relaxed and straight. What Bill writes about using the first slot as a locater then using the wider slots for ease of assembly is a good technique but it should not be necessary except that it does make for an easier job of gluing up as the dominos do fit very tightly. I find the wider slot option makes the slots too wide so in some instances I will just plunge twice - to each side bit of my mark (on one board only) and that helps a lot. Nonetheless fRED you should be able to get accurate results just going to your marks - if they are crisp and accurate as I described.

[Prashun Patel]

Unless clamping will pull the joint out of alignment (like on miters) there's little reason NOT to use the wider setting on one side of the joint.

Like a drill bit, the cutter wants to skate until it plunges below the surface. It's difficult to keep it in perfect alignment without some kind of lateral limiter like the pins or a clamped block; the handle sometimes just isn't enough. Is your Domiplate restricting the lateral movement enough?

[Jeff Monson]

I'm with Sam, I use pencil marks and align them in the window, never have issues, I also use the tight setting as much as possible. I find it very important on the technique I use to plunge the tool. I make sure my workpiece is securely held down. I use one hand firmly on the fence handle, I hold the other end of the tool right where the power cord attaches. I also make sure to let the tool do the work, especially on 1st contact.

[Chris Padilla]

I'm with Sam and Jeff. :)

Pencil line on both pieces.

Clamp everything down that needs to be cut. Any movement of the wood will mess things up.

Grip the Domino firmly and make sure the fence is fully seated and up against the wood. Rock the Domino a bit to ensure it is fully seated. Always double-check before plunging. I like to look once more AFTER I turn the Domino on. Sometimes turning it out can knock things a bit out of alignment.

Now SLOWLY plunge the Domino. Moving too fast could cause you to move the whole tool and throw the joint off. As Jeff said, let the tool do its work cutting a clean mortise.

Make sure your cutting bit is sharp, too. If it is dulling, might be time for a new one or a sharpening.

[Mark Carlson]

Could the shop made domiplate center line be off? Do you get similar results with the fence?

~mark

[fRED mCnEILL]

All the domino plate does is locate the mortise heighthwise on the work like the fence would do. It is the score on the bottom of the domino that locates the mortise width wise.

[Jeff Monson]

It is the score on the bottom of the domino that locates the mortise width wise.

Fred, I guess I never use the bottom scores to line up my cuts, I rely on the clear window on the top of the unit to line up my cuts. The top window is adjustable, the bottom (someone correct me if I'm wrong) is not.

[fRED mCnEILL]

With the dominplate you use the domino upside down so the only registration mark you have is scored on the bottom of the domino.I am using a 4 mm bit on 1/2 plywood and I don't think the regulare fence adjusts enough to use on 1/2 ply.
I will do some more tests using the methods described above. Its is quite possiblly my technique giving the problem.

[Chris Padilla]

Pictures are always worth a 1000 words, Fred. Post some if you can.

[Prashun Patel]

Are you using dust collection?

[Jeff Monson]

Try setting your fence height to 6mm and use the top window for line registration (set the plate aside for now). Let us know how that goes, maybe more of an issue with the plate and the lower marks.

[Sam Murdoch]

Are you using dust collection?

Good question as doing this without the vacuum attached certainly effects the quality of the cuts - or should I say - the accuracy.

[Erik Christensen]

I have used a domino for plywood case assembly since the product was first released - I have used about 2,500 5mm domino's since then (about 2/3 through my second bag of 1,800) and here is what has worked for me. I have read that there is no real structural strength difference between a domino joint where the mortice is precise vs slightly oversize - so the only benefit to making both pieces with precise mortices is registration. To me lateral registration in case assembly is a liability. In case construction the 2 pieces meet at right angles so one mortice is in the face and the other in the edge. I cut all face mortices precisely and all edge mortices one click oversize - that way I can can adjust the fit during glueup to get the exact fit i need. This takes a lot of the stress out of cutting domino mortices knowing you don't have to get overly finicky on lateral precision - get the domino face & fence so it perfectly flush and get the registration mark "close enuf" and focus on a smooth even cutting plunge. There is more technique to using this tool than one would think from inspection - I can tell you when time comes to assemble cases it is VERY obvious that some were cut at the end of the day when I was tired and not paying as much attention as i should to getting a perfect cut.

[Bill Wyko]

Follow the instructions that it comes with it, there is a description on how to center the cursor. It's pretty easy. Loosen the cursor, move it over 1/2 of the offset you are encountering, that should center you right up.

[fRED mCnEILL]

Well, I have done some more testing and turns out the culprit is ..............operator error. As the error only occurred on flat face mortises it turns out the domino is more difficult to hold firmly in that position.
BUT, I also used Erics method of doing wider mortises in the edge and narrow mortises in the flat face and it sure makes it a lot easier to line everything up.
Thanks to everyone for the suggestion. Using dominos to do case work construction with plywood sure is slick.

Regards

Fred

[Brian Jarnell]

I overcome this by making my own dominos, slightly smaller, that allows for some lateral adjustment.