Lines of dominoes: Cross-stop or scribe-and-align-with-cursor?

[Jim Morgan]

I am new to the world of Festool Dominoes. I had my eye out for one on CL for a while and finally got a Fat Man at a decent price (never did see any Little Boys come up). With a Seneca adapter and a set of smaller bits, I am good for any size of domino.

My current project is a(nother) platform bed, and there are several places where I am using lines of dominoes, for example joining side- and end-rails to the plywood that the mattress will rest upon. I did some test pieces using the cross-stop and cutting lines of narrow mortises, but never could get them to align. I know there is a way to calibrate the cross-slides, but after about five attempts (cut several mortises, adjust, cut several mortises, adjust, try to get them to line up), I gave up. Perhaps someone has a better way to calibrate the two cross-stops to each other. Of course, I could follow the Festool suggestion to just cut narrow mortises at one end for alignment and then cut the remainder of the mortises at the wider setting. That works, but it offends my sensibilities: I moved up from a biscuit joiner to the Domino for greater precision, and those wide mortises are pretty sloppy.

Instead, I have been scribing domino locations on pieces to be joined and aligning the cursor with the scribe lines to cut narrow mortises. This is slower and more painstaking than using the cross-stop, but it works! As a hobbyist, I am not as concerned with efficiency as others might be, but I was wondering what other folks out there do.

[Michelle Rich]

offends your sensibilities? :-) thanks for the giggle. I would suggest to you that severely tight mortises in this situation are not really needed. Festool's way of doing it is surely strong and will do the job. It's not as tho the mortises are sloppy, their way. Just not having to force them in. and remember glue today is stronger than wood. Those joints will hold up. I have used the cross stop method for years and years, and have never had a customer call me because they failed. Nor have any of my personal pieces failed. Hope this is reassuring.

[Jim Morgan]

Thanks, Michelle. That should have been "my delicate sensibilities" :) So no evidence that 'loose' mortises compromise joint strength?

[Cary Falk]

So no evidence that 'loose' mortises compromise joint strength?

I will go on record and say it does compromise joint strength. I just bought a used Domino and used it to put together a couple of sofa tables. I couldn't get the cursor aligned to my liking so I used the larger setting. I was not happy with the strength and ended up securing almost all of the joints with a pocket hole screws. My JessEm doweling jig would have made a stronger and more accurate jig. I wish the Domino had a setting for a setting for a hair wider and not ginormas and mack truck. I will continue to work with the Domino but I do not like the larger setting unless you are using it for alignment. Your joints may not matter depending on where the stress is . Most of my joints were similar to a table leg to apron type of joint.

[Brian Holcombe]

The plywood is not normally joined in, typically the frame is substantial to handle not only the weight but the occasional racking forces applied and the plywood either set in and screwed down or just set in.

[Jim Morgan]

Cary, I lucked out in having a cursor that seems to be perfectly aligned - the rows of dominoes that I have been doing by scribe-and-align/narrow mortise go together without forcing. Half Inch Shy had a YouTube video on aligning the cursor that you might find useful.

Even with the strength of modern wood glues, it seems to me the narrow mortises result in a mechanically superior joint.

[Jim Morgan]

Brian, in this case, there really isn't a frame, just a lip around the plywood platform. I used 80 mm Dominos on 6-inch centers out of concern with weight and racking of the lip - we'll see how that holds up.

[Jacob Mac]

https://youtu.be/CLAfpRxihqw

[Brian Holcombe]

Brian, in this case, there really isn't a frame, just a lip around the plywood platform. I used 80 mm Dominos on 6-inch centers out of concern with weight and racking of the lip - we'll see how that holds up.

The best and most interesting advice I've received, WRT furniture making was; 'Beds fail at the most inopportune times, so make it strong'. I'll offer you the same advice, because in all frankness this sounds like not anywhere near enough structure.

Two adults is anywhere from 250-500+ lbs depending on some variables, that is static weight.

[lowell holmes]

I thought butterfly's and domino's were for alignment with the strength of the joint being derived from glue.
What am I missing?

[Jim Morgan]

The best and most interesting advice I've received, WRT furniture making was; 'Beds fail at the most inopportune times, so make it strong'. I'll offer you the same advice, because in all frankness this sounds like not anywhere near enough structure.

Two adults is anywhere from 250-500+ lbs depending on some variables, that is static weight.

Brian, maybe you are thinking of a traditional headboard-footboard-side rail design, in which case, you would be 100% correct. Here, however, there is a sturdily constructed storage structure underneath the plywood platform, so I am not worried about supporting the weight of the bed + occupants, even under conditions of vigorous activity.

The edge of the platform is flush with the storage structure, but the lips on the sides and foot - about 3" wide - are cantilevered. Imagine 250 pounds perching on the edge of this I would not trust an unreinforced joint to hold up here.

[Jim Morgan]

I thought butterfly's and domino's were for alignment with the strength of the joint being derived from glue.
What am I missing?

Lowell, biscuits provide (some) alignment while adding little or no strength to joints. The domino joint is a different story - it is really two complementary mortises joined with a slip tenon. In a traditional M&T joint, the tenon does more that just align the joint for glue-up. Good M&T joints fit snugly, both along the cheeks that provide the gluing surface and along the edges, to combat racking. In it's narrow setting, the Domino cuts mortises that fit snugly all the way around. In the wider settings, the mortise is snug along the faces, but loose along the edges, so the mechanical resistance to racking is lost.

[Jim Morgan]

https://youtu.be/CLAfpRxihqw

Jacob, thanks, that's the vid on cursor alignment I was thinking of. I haven't been able to find anything comparable on calibrating the cross-stops.

[Brian Holcombe]

Brian, maybe you are thinking of a traditional headboard-footboard-side rail design, in which case, you would be 100% correct. Here, however, there is a sturdily constructed storage structure underneath the plywood platform, so I am not worried about supporting the weight of the bed + occupants, even under conditions of vigorous activity.

The edge of the platform is flush with the storage structure, but the lips on the sides and foot - about 3" wide - are cantilevered. Imagine 250 pounds perching on the edge of this I would not trust an unreinforced joint to hold up here.

Ah, that makes sense then. It still strikes me as being odd to perminantly mount the plywood. Normally it is viewed as replaceable not integral. In a platform bed all the same. One would typically wrap a support around the interior of the frame and the plywood sits inside if it.

I build work that is typically generalized as either contemporary European or Japanese, never really American traditional.

I made this recently to hold a washer and dryer, similar to a platform bed in design. The center has a leg to support, the interior a heavy ledge for the plywood and the plywood just sitting in place.

https://brianholcombewoodworkerblog.files.wordpress.com/2017/06/img_6838.jpg

[Jim Morgan]

Ah, that makes sense then. It still strikes me as being odd to perminantly mount the plywood. Normally it is viewed as replaceable not integral. In a platform bed all the same. One would typically wrap a support around the interior of the frame and the plywood sits inside if it.

I build work that is typically generalized as either contemporary European or Japanese, never really American traditional.

I made this recently to hold a washer and dryer, similar to a platform bed in design. The center has a leg to support, the interior a heavy ledge for the plywood and the plywood just sitting in place.

https://brianholcombewoodworkerblog.files.wordpress.com/2017/06/img_6838.jpg


Very cool, Brian.

The plywood is just screwed to the support structure, so that can be removed. I've been thinking of using pocket screws (from the bottom) to draw the lip tight to the edge of the plywood. If this weren't glued, the lip could be removable as well. But would dominoes and pocket screws, sans glue, be sturdy enough?

[Peter Aeschliman]

'Beds fail at the most inopportune times, so make it strong'


even under conditions of vigorous activity.

You guys are cracking me up! haha

[Cary Falk]

biscuits provide (some) alignment while adding little or no strength to joints. .

Depending on the joint they add a lot of strength.

[Jim Morgan]

You guys are cracking me up! haha

Just trying to be discreet. ;)

[Jim Morgan]

Depending on the joint they add a lot of strength.

Cary, that depends on the biscuit as well - I've been seeing more and more that are so thin that, even when swollen, they fail to make firm contact with the sides of the slot.

[Cary Falk]

I think pocket screws would be plenty strong

[mreza Salav]

Don't understand why you insist on having your mortises tight side-ways. Just cut them a little bigger and there won't be any issues.
Have used thousands of dominos and always worked fine.

[Brian Holcombe]

It's tough for me to say in the abstract, since I don't have an idea of how you're building supports and so forth, but I did a blog post on this one on my website, which you're welcome to have a look at, and may provide some insight.

I tend to err on the heavy side, Id rather over build than repair a failure. I do some minor calculations on occasion but often enough I will simply stand family members on things and observe for deflection. :D I also like things to be repairable, another furniture maker told me earlier on that he made things to be repaired since he wanted to make things easier on himself in the future.

Also it is easier to move heavy furniture in pieces rather than as a whole.

[Jim Morgan]

Brian, lots of good stuff on your website. Which post did you have in mind?

[Brian Holcombe]

Two posts come to mind;

https://brianholcombewoodworker.com/2017/07/13/tokonoma-plinth/

https://brianholcombewoodworker.com/henrys-bed/

[Jeff Booth]

FWIW - I have been using the DF500 for about 10 years, I bought one new when they came out. I do love the machine and have built countless things in all shapes and sizes with it but like all tools one has to develop their own usage system. Like some of the others on this thread, I do not like the wide sloppy mortises, I agree with the comment asking why Festool thought they have to be so huge - especially with two sizes, adding a +0.5 mm feature would have been more useful than the +5mm middle sized mortise. For me, the only thing the extra wide mortise is good for is when I cut my own wide tenon for the occasion project that is too narrow for more than one tenon but requires more strength than supplied by the standard loose tenon.

Therefore, I rarely use either of the wider mortises, to me the extra time involved in fitting it all together is worth the extra strength, as another member said, it does depend on the forces exerted onto the joint. The only time I use the wide sloppy mortises is if I am using it more for alignment that may include shear forces but not racking or pulling forces.

I have found the cross stop and mortise pin-alignment system to be useless for cutting multiple mortises - for me personally it causes more trouble than it is worth, thus everything is done with a tape/square onto pencil or a knife (and transferred across the joint at the same time) and cut with the cursor. This pretty much always works with two tenons, but when things do not fit perfectly with 3 or more mortises I often can address that with just a little gentle paring on a tenon with a chisel. For inside projects I also have found that fitting it all together with hide glue is a good way to deal with multiple mortises, the hide glue acts much more like a lubricant than PVA and the longer assembly time allows me to go around the whole project gently tapping with a mallet until I can fit it all together.

[Jim Morgan]

For inside projects I also have found that fitting it all together with hide glue is a good way to deal with multiple mortises, the hide glue acts much more like a lubricant than PVA and the longer assembly time allows me to go around the whole project gently tapping with a mallet until I can fit it all together.

Jeff, thanks for the hide glue tip - I have a bottle of Old Brown Glue in a refrigerator that I haven't used yet.

If I were making traditional M&Ts, by whatever means, I would be embarrassed to make one as sloppy as what results from the wide domino setting (DF700 only has tight & super-wide settings). Why should I work to a lesser standard of precision with the Domino? Again, it's just my sensibilities, which some agree with and others find ridiculous. Chacun a ses gouts.

Apparently, however, no one has figured out a method for fine calibration of the cross-stops.

[Prashun Patel]

I have never used the cross stop.

On cross grain joints, I prefer to use the exact fitting setting. I strike lines across the joint and use the cursor.

If there is an alignment issue - which happens rarely, I will take a shaving off the edges of the domino on one side.

For cross-grain joints, I'm rarely using a huge row of dominos. I use rows on edge-edge joints where the only function of the dominos is alignment; so I don't mind using the wider setting here.

[Brian Kincaid]

I don't use the cross stops unless I'm using it for edge reference.

For glue-joints I just align the boards on a workbench then scribe a pencil line across the joints then use the cursor to cut each joint on the 'tight' setting.

I only use the loose settings when putting together a floating joint where one side is cut 'tight' and the other side is cut loose, and assembled without glue on the loose side. Good example of this is a breadboard end.

-Brian

[Jim Morgan]

I only use the loose settings when putting together a floating joint where one side is cut 'tight' and the other side is cut loose, and assembled without glue on the loose side. Good example of this is a breadboard end.

-Brian

Great idea on an easy way to make breadboard ends - glue in one or two dominoes in the middle and let the others float in over-sized mortises. Paired with a sprung joint, should be just the ticket.