Domino strength

[AndrewG]

Hi all,

I’m designing a wall mounted chest and looking to make it out of 1/4 sawn material. I’d like to use miter joints so I can have flowing grain all around the cabinet/chest case.

My question is, how strong would the 10mm dominos be? I reckon the cabinet would be roughly 20” wide, 35” high and 12” deep. It will be full of drawers for jewelry and bits and pieces. I haven’t finished designing it.

The cabinet will have a rebate cut for a 1/2” or so thick back. I’ll then use a cleat which will sit flush between the cabinet back and the wall. So I’d say there’d be a fair bit of force on the top of the case.

The only thing I can think of to strengthen the joint is to use splines. I’m really not keen on this as I’m designing the cabinet to be slick and flowing. So what do you reckon? Will dominos be strong enough?

I appreciate your help. Thanks!

 

[Birdhunter]

I’m wondering how you would be able to use 10mm Dominos unless your stock is really thick.

 

[ear3]

What's the material thickness? 

If it's 3/4-1", I would be comfortable doing 5 or 6mm dominoes on the assembly.  A mitre joint already has some inherent strength because of the greater surface area made up by the joint.

If you go thicker dominoes, keep in mind you will have to cut them short to avoid plunging through the other side, and you want to be very careful they aren't too thick so they actually weaken the joint (by forcing you to place the mortise too close to either of the board faces).

 

[AndrewG]

I’m wondering how you would be able to use 10mm Dominos unless your stock is really thick.

The cabinet will be slightly over 3/4”, so you’re right. I still have a fair by of planning to do. I’ll use the largest size I can.

 

[sheperd80]

I think 3 or 4 dominoes across the 12" width of each joint would be plenty strong.

With 3/4" material i think youll be limited to 5mm dominoes on a miter joint. Anything bigger will be too long and stick out the face of the piece iirc.

Sent from my SAMSUNG-SM-G890A using Tapatalk

 

[Birdhunter]

Agree 5mm is about max size. 

Suggest you reconsider splines. I am a huge Domino fan, but prefer splines for beveled joints. I cut the grooves for the splines on a very accurate table saw. Thus, I get excellent alignment. If I didn’t have the table saw, Dominos would be the next choice. Getting perfect beveled joints with Dominos requires great precision. Practicing on scrap would be a good idea.

I do not agree about the glued joint being strong. That’s not been my experience.

 

[eeeesh]

Splined miter or maybe even a lock miter.

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[AndrewG]

Thanks for the replies. So it looks like 5mm dominos is the way to go, but I’ll need to practice on some scrap material to get clean looking miters. Any tips to get perfect 45 degree placed mortises with the domino?

I have the set up for cutting splines, and I have done them before, but it’s not the look I’m after on this particular design. I do agree it will help strengthen the joint, but I’m hoping the dominos will be plenty strong when the cabinet is full of drawers and it’s contents.

Thank you

 

[Birdhunter]

I didn’t have much luck free handing the Domino doing 45 degree mortises. I ended up making a jig to orient the Domino. Someone like Peter Parfitt could probably help.

 

[Stone Message]

I take it that the drawers will be supported within the upright sides. Also, were you to have doors then these too would be joined to the two upright sides.

The back, at 1/2", is quite substantial and will be glued in place.

The top and the bottom will play no real part in the strength of the cabinet. Therefore, I would not try and make a fancy joint at the corners. A straight mitre which is just glued will be more than strong enough.

Take a look at this video from about the 9 minute point:


I used this technique for all the panel joints of my keyboard cabinet, including the top which is a simple right angle with no supporting side structure. For an overview of the whole project which gives an idea of the overall design see this video:


Peter

 

[AndrewG]

Thanks Peter I’ll check the videos out

 

[fshanno]

When I use dominos when mitering panels I sand them to get a fairly loose fit.  The pieces will come together on assembly and the face of the miter more than the direction of mortise will be the deciding factor in squareness.

 

[locaholic35]

Thanks Peter,

Haven't done a lot of miter glue ups but they have never gone too well.  Excited to try your tape technique next time.  Thanks for sharing

 

[Stone Message]

Thanks Peter,

Haven't done a lot of miter glue ups but they have never gone too well.  Excited to try your tape technique next time.  Thanks for sharing

I will be showing in an upcoming video some simple drawers made of 9 mm MDF that are just mitred and glued and are being used to hold a variety of tools including hammers and other heavy stuff.

Modern glue on a mitred joint can be very effective and last throughout years of abuse.

Peter

 

[greg mann]

Set you mitered pieces back to back and with the edges and ends perfectly aligned. This will give you a 90deg. Peak to nest the Domino on allowing you register off two miter faces. Works great. I do believe there is an illustration of this technique in Rick’s Domino tutorial, which I believe is still archived on the Festool USA website.

Edit: I went and checked and my memory is flawed. The example there for a mitered joint  shows the fence at a 45 degree angle. With your two pieces with the long sides back to back the fence can be left at 90 degrees and is far less likely to move on you.