4 x 20 Dominos

[Mini Me]

I was short on space to fit a Domino in so I measured the width of it to see how close it was and for some reason I measured the length as well which had no impact on the job. I was surprised to find my bag of 4 x 20 Dominos were 18.3mm long and not 20mm as printed on the bag. I have no issue with the length but it surprised me that they were not as specified.

 

[onocoffee]

IIRC, from one of Sedge's videos, the Dominos are cut slightly shorter than the stated length to allow for the "ejection" (I'm lacking the correct term) of excess glue.

 

[hdv]

Yep, that's how I understood it as well. This was done on purpose to allow for the glue to go somewhere. Otherwise you'd have a real hard time getting the domino joints to fit/close properly. For the strength of the joint it won't make a significant difference.

 

[ChuckM]

You can find the same observation on all other domino sizes. The mortises are milled slightly deeper than the dominoes are long (i.e. to the stated spec. of the dominoes) to provide a glue reservoir effect.

 

[smorgasbord]

I think it's well known that dominos are shorter than the nominal length.

However, is it true that the DF500 and DF700 both cut mortises slightly deeper than the nominal depth, or do they cut exactly to that depth? I recently cut some 6mm on my DF700 and they appeared to be 1mm deeper than the "15" or "20" depth I chose. However, I am running the Seneca adapter to be able to use the 6mm bit and so that might be the issue.

 

[ChuckM]

I happen to have a piece with mortises cut with my DF500 for some 4x20 tenons. The mortises measure 10mm deep on the whole.

 

[luvmytoolz]

All the tenons are shorter than the nominal size to allow for the glue, with the longer ones around 3mm shorter.

 

[Crazyraceguy]

If the mortices were exactly half the length of the Dominos, there would always be the potential for the joint to not close up. A little too much glue, a crumb of dust, anything, could hold the joint open.