DF 500 tenon use

[HometownFurnitureMore]

Is there any set rules to use what size other then the 1/3 rule.

The manual says to use 8mm on 3/4" stock. That seems kind of big to me.

I also have seen posts where 5mm is used on 3/4" stock.

Just wanting to get feedback from you all on what sizes you use for what stock.

Will mainly be using 3/4" stock, and some 2x4,2x6 stock.

Btw, i bought my domino last week and like it so far.

 

[mouppe]

I think there was a similar thread on this a short while ago which may be worth searching for.

As for the 1/3 rule I think it's one of those "sounds good so it must be right" rules that has been repeated so many times it has become fact.

Traditionally, the mortise would typically be sized according to whatever chisel width was most suitable for the job so you could chop out the mortise as quickly as possible. It may have been around a third of the stock width in some cases, but it also had a lot to do with what was appropriate for the joint. In joints where there was a lot of lateral force, you would want to leave more meat around the mortise hole to prevent the wood splitting. Maybe the tenon could be less than 1/3 in this case. If the tenon wood is stronger than the mortise wood, you may also want to thin the tenon.

Also, the length of the tenon is often more important than the width.

When I am using dominos for alignment reasons, such as joining planks to make a wide panel, I'll use a very small domino, usually the 5mm one. No more is needed, and I find it quicker, cheaper and easier to use small dominos.

Bottom line is I would go with what feels and looks right rather than being wedded to a rule. I buy twice as many 5mm dominos as any other size because I tend to use it more often than the others even in thick stock.

 

[Jesse Cloud]

Previous post pretty well nailed it.  Though some folk treat the 1/3s rule almost religiously, it should just be a rule of thumb.

The most important things about a mortise and tenon joint, which all dominoes are, is the amount of surface area that gets glue and the fit between the mortise and the tenon.  The second is pretty much guaranteed by using a Domino, the first is what you design to.

Unless you are building something with huge stresses, like an entry door, the thickness of the mortise is not the determining factor on  design, so long as you leave enough meat in the rest of the joint.  Two dominoes are likely to give you more area than a longer one in most situations.

Goiing back to your example, in 3/4 (19mm) stock - you can use a 6mm or an 8mm or a couple of 4mm's successfully.  I mostly use 8mm, but wouldn't argue against 6's. 

Sometimes we tend to overthink joinery...  Have fun, enjoy your Domino

 

[Roseland]

In ply and hardwood, I use 6mm, but in MDF I'd use 5mm.

I'd strongly recommend a Domiplate; it transformed the accuracy I get.

Andrew

 

[HometownFurnitureMore]

Thank you all for the great info.

 

[grbmds]

I would think it would depend on what you using them for? For example, drawers made from 19mm Birch Ply should be joined with 5mm Dominos unless  you want to cut the Domino down to fit, since the depth of the side mortises is limited by the thickness of the plywood. If you are joint plywood or solid wood edges then longer Dominos make sense and aren't limited by the thickness of the wood. I've used 5's on drawers for my workshop tables and they make a very strong joint even for drawers which might hold some weight.