Domino - Mortice width settings from a Newbie

jbarr

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Mar 27, 2021
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First real post after buying a Domino 500 yesterday, my first Festool tool and yes am i excited  :). I have read all the manuals including the supplemental and watched many videos including Peter Parfitt's excellent video. I cut up a whole pile of scraps to practice and most of the joints are near perfect which put a smile on my face. Occasionally one was slightly out (probably user error) so i thought I'd try making the first one tight and then all the others on the middle setting as seen in many videos. Here's my confusion! Should the 2 tight fittings on each piece lock into each other or should the tight fitting on one piece mate up with a loose fitting on the other. One video said the 2 tights should match to avoid rotation but when that happens I don't seem to have any wiggle room which is the wole point of changing widths.
For those of you who adjust the widths for most joints which way do you do it. Tight to Tight or tight to loose?
 
It depends.

In jointing (gluing up two boards or more edge-to-edge to together): Set dial to tight for all mortises on one board, keep the tight setting for the first mortise on the mating board, then reset the dial to wide for the rest of the mortises. The first tight mortise on each board allows for alignment.

In butt jointing or shelves, same as above, but where I can, I often use the tight setting for the endgrain edge (easier to pull out the dominoes after dry fitting). The mating board (face/edge grain) has only one tight mortise and all others are wide mortises.

When strength is critical, for example, in twin/double mortises or chair legs, mortises on both joints/pieces should be cut in the tight setting only.
 

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I usually do tight on one board and one step wider on the other. If it is a small piece I will make the first mortise tight on both boards. I’m saying what I do is right but it works for me. Hope this helps you.
 
ChuckM said:
Doesn't having one tight to tight mortise not allow for any wiggle room even if the others are all tight to loose?? 
I tried both ways and I still found no wiggle room for at least one tight to tight.
In my case I found I got the best results with all mating mortises tight to loose using pencil marks and using the paddles on small pieces I found tight to tight was perfect.
I'm still open to suggestions but it seems there is no highly recommended way but rather what works for you. I'm still blown away by this tool and its only one day.
 
jbarr said:
Doesn't having tight to tight mortises not allow for any wiggle room even if the others are all tight to loose??

Yes, but you’ve only got one spot where that’s the case, and you can make it the one closest to the edge, where you can use the integrated stop. You’ve got a pretty good chance at not getting out of alignment on that single mortise.

Your risk of misalignment goes up significantly as you go across a piece, either locating with pencil marks or the detachable wings.
 
Dr. P. Venkman said:
jbarr said:
Doesn't having tight to tight mortises not allow for any wiggle room even if the others are all tight to loose??

Yes, but you’ve only got one spot where that’s the case, and you can make it the one closest to the edge, where you can use the integrated stop. You’ve got a pretty good chance at not getting out of alignment on that single mortise.

Your risk of misalignment goes up significantly as you go across a piece, either locating with pencil marks or the detachable wings.

That makes perfect sense thanks! I've found using the paddles very accurate and using them for the first tight to tight mortise on each board is a great idea
 
I’ve built lots of pieces using both the 500 and the 700. I use an all tight on one board and all medium on the other board. This gives me a few seconds to tap the pieces into perfect alignment. I just don’t want to rely on perfect alignment in using the tight to tight method. Perfection can be elusive. You get the tight to tight mortises off a hair and you have a Royal mess.
 
Birdhunter said:
I’ve built lots of pieces using both the 500 and the 700. I use an all tight on one board and all medium on the other board. This gives me a few seconds to tap the pieces into perfect alignment. I just don’t want to rely on perfect alignment in using the tight to tight method. Perfection can be elusive. You get the tight to tight mortises off a hair and you have a Royal mess.
That's 2 votes for all tight on one board and all medium loose on the other. As Chuck says it depends. I think I'll use this method for most joints and if strength is more important, which is very rare for the work I do, I'll use the tight setting. Thanks for all the replies. I found it interesting, however, that Peter Parfitt leaves his domino on the tight setting all the time. Each to their own
 
did tight to tight for the longest time. but the more i use it the more i see how it's not important and tight to loose is much more cruisy and relaxing
both cutting and glue up especially
 
I’d bet there is zero strength difference between tight to tight and tight to loose and loose to loose. The tenon provides alignment between reference surfaces and tensile (pull apart) bonding. The alignment of reference surface to reference surface is completely independent of mortise widths. The tensile strength is totally dependent on the degree of glue bonding between the tenon and the mortise surface. With only one tenon (tight to tight) enjoying contact along its edges there would be only a tiny advantage.  All the other tenons have gluing contact on their top and bottom surfaces, thus independent of mortise width.
 
Birdhunter said:
I’ve built lots of pieces using both the 500 and the 700. I use an all tight on one board and all medium on the other board. This gives me a few seconds to tap the pieces into perfect alignment. I just don’t want to rely on perfect alignment in using the tight to tight method. Perfection can be elusive. You get the tight to tight mortises off a hair and you have a Royal mess.

This Royal mess is a real thing, and is not just limited to the Domino joint. It can happen to dowel joints, M&Ts, etc.

That's why the paddles/pins on the machine must be checked/properly calibrated to be precise to give you the confidence to do the tight to tight alignments.

Despite what some may claim, it's humanly impossible (at least for 99.9% of the users whose eye sight is not laser sharp) to rely on the scribed line on the fence and the pencil lines to cut tight mortises and align pieces 100% of the time. I've not met any DF500 users who can do that. It's no different from using a stop block vs positioning pieces by sight for repetitive cutting or boring.

Granted, not every DF500's paddles or pins are factory tuned to our desire. There're threads in this forum and instructional info. elsewhere on how to dial them to satisfaction. If the paddles/pins are out, it can cause alignment issues when using the trim stop on long boards.

The dry assembly process should also reveal any joint fitting or alignment issues and allow us to fix them before the actual glue-up.
 
Birdhunter said:
I trust the locators on my DDF400 but not on the 500.

Why? Because they've become imprecise again after you've calibrated them?

What about the 700? Are its pins reliable for aligning pieces?
 
I do things a bit differently... [tongue] however it's worked well for me.

1. I've never used the paddles, I always scribe THIN pencil lines and use the cursor on the Domino to line things up.
2. For boards shorter than 4 feet, I use tight-to-tight on every mortise.
3. I also mark pairs of boards at the same time so that that the lines will always be exactly placed.
4. For boards longer than 4 feet, I'll start in the middle of the board with a tight mortise on each side, then on one side all the remaining mortises are tight and on the other board all the remaining mortises are loose. By starting in the middle, compared to an end, you'll reduce the potential error by 50%.
 
Cheese said:
Snip.
By starting in the middle, compared to an end, you'll reduce the potential error by 50%.
Interesting approach.

Could you elaborate a bit on how starting from the middle with two pencil lines would reduce errors (assuming the error you referred to is alignment discrepancy)? I also assume that before you mark the two middle lines, somehow you manage to flush up the ends of the two mating boards, and keep them together (with clamps?).

I've tried pencil lines 0.3mm, 0.5mm & 0.7mm (regular pencil lead), and the results have been hit-or-miss for me over the years. But not with the paddles -- dead on every time and 100% of the time (unless user error is made). The paddles were verified again in a Nov. sample test for being spot-on up to 0.001".

Lucky for me, the factory setting has been as precise and accurate as shown in the image since Day 1 (5 years ago). I've never dropped or rough handled* the machine. I know some owners have complained about their paddles being out of alignment upon delivery from the factory/vendor.

* In videos including some produced by Festool, I've seen people banging or dropping their machine on the bench in a rush manner or allowing the body to spring back in full force, etc. I don't know if that would do any harm to the precision features of the machine, but I never do anything like that.
 

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Mafell DDF40 vs Domino 500 locators. The locators on the Mafell machine AND the accessories have been very reliable. I’ve tried using the locators on the 500 several times and have been disappointed. The locators on the 700 seem to be very precise. I trust the 700’s locators explicitly.
 
ChuckM said:
Lucky for me, the factory setting has been as precise and accurate as shown in the image since Day 1 (5 years ago). I've never dropped or rough handled* the machine. I know some owners have complained about their paddles being out of alignment upon delivery from the factory/vendor.

* In videos including some produced by Festool, I've seen people banging or dropping their machine on the bench in a rush manner or allowing the body to spring back in full force, etc. I don't know if that would do any harm to the precision features of the machine, but I never do anything like that.

Agreed totally. I always handle this as a precision tool, giving it the care it should receive.
My paddles have been perfect from day one, but I did have to move the cursor ever so slightly. This was found from doing an accuracy check that I wouldn't have necessarily known to do without watching Youtube videos back when I got my first DF500 years ago.
 
Birdhunter said:
Snip.
The locators on the 700 seem to be very precise. I trust the 700’s locators explicitly.

I wonder if the third (?) generation of DF500 would adopt and use the DF700's type of "flip-able pins" instead of paddles, or revert back to the pins if the patent issue no longer exists. 
 
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