Domino Joiner - Shop-made Mortise Center Finders

[ChuckM]

Sometimes we need to find the centerline of a milled mortise (to transfer the line or to repeat the cut to fix an error, e.g.). Someone sells a 3D printed product (about $30 Cdn for a pack of 6 of one tenon size -- so you need to spend $150 if you want to cover all the sizes). Another fellow woodworker cut a tenon in the middle partially and used it with a square to transfer centerlines.

I found it simplest to make a bunch of center finders by using the paddles or spring stops. So I marked pencil lines around the blocks 37mm from the edges, and cut the mortises. The pencil lines give the centers.

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The right paddle was found to be off, not exactly 37mm from the cutter's center like the left paddle, so I replaced it before continuing.

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[ChuckM]

It just dawned on me that the (slightly sanded) dominoes themselves can be made into center finders by drawing center lines on them:

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[derekcohen]

I have done something similar ...

I built a little jig to align the ends of the 10mm mortices to be made with a Domino DF500 ...

The stretchers are 125mm wide and 26mm thick Jarrah.

The loose tenons are 58mm in total length (29mm each side), made in the same Jarrah as the stretchers ...

The fit is tight (not too tight), which is important and the strength lies with the faces and not the ends. The is about 3mm each end for wiggle room ...

This is going into two single beds ...

More on the joinery later.

Regards from Perth

Derek

 

[promark747]

[quote author=derekcohen]

The fit is tight (not too tight), which is important and the strength lies with the faces and not the ends. The is about 3mm each end for wiggle room ...

[/quote]

I agree with that and would therefore not spend the time to round over the edges of those tenons.

 

[ChuckM]

Hi Derek,

While it's true that in your case, the joints in the head/end boards are not subject to the kind of racking force as in a chair, they're still structural joints. There're no advantages of leaving a big gap of 3mm on each side, more than twice the normal room some leave for floating tenons when wide tenons are made of a different wood species. Any reasons why you didn't cut the tenons the same size as the mortises as only one species of wood is used.

In any structural joint, I wouldn't leave any gaps at all by using the tight Domino setting for all mating parts. 

 

[derekcohen]

Chuck, all that these joints are for bed ends. These do not carry any load from the mattress. I built in wiggle room for the end mortices, and plan to pin these anyway.

The side rails carry all the load. These will have tight-fitting (unglued) double-mortice-and-tenon (plus bed bolt).

Regards from Perth

Derek