Mortise across grain

[Dale Cruea]

I am making a jewelry chest from African mahogany.
This chest is about 41" tall and will have 2 sections.
A top section and a bottom section.
The bottom section has a large, flat top piece.
I wanted the sides of the upper section to be mortised to the top of the base.
As I started cutting the mortises I noticed that I was mortising across the grain.
This will not leave any long grain to glue to.

Question is;
Is it ok to mortise across grain and will it hold when I am done?

Other than the back of the upper section there will not be any other material to hold the bottom of the upper section together at the mortises.

Turning the top of the base 90 degrees to mortise with the grain will put the end grain to the front of the chest.
Wondering how that would look?????????

[Casey Gooding]

If I understand what you are saying, then your tenons would be very fragile as the grain would be running on the short. In this case, floating tenons may be a better option than what you had in mind.

[James Taglienti]

They say that you shouldnt do that. It would probably do better with a series of smaller mortise & tenons to give more long grain glue area, a sliding dovetail, or screws from the bottom of the slab into the sides. I think that if you are too far along in your mortising,i would just go ahead and finish it up, and add a few screws, maybe with expansion slots. How faris it from the mortise to the edge of the top? Careful as the joint could break in this area

[Jack Curtis]

...Question is;
Is it ok to mortise across grain and will it hold when I am done?

Other than the back of the upper section there will not be any other material to hold the bottom of the upper section together at the mortises....

No. OTOH, it may be you really don't need much strength in those mortises, depending on how heavy African Mahogany is; however, if the chest should fall off a dresser....

[Dale Cruea]

Thanks guys.
I just started on the base top and I think I will re-design these joints.
I sliding DT won't work because the joints are blind or stopped on both ends.
I may just use screws also.

[James Owen]

If there is enough depth in your mortises, take a look at draw boring your M & T joints -- if the glue fails, for all practical purposes it won't matter.

[Frank Drew]

Dale,

If it's not too late for a slight design change, you might consider making this piece in two distinct sections, attaching the top section to the bottom once both are constructed. As you note, the mortises you've planned won't provide much of a glue joint, but they'd be fine for locating where the top sits on the bottom; barring earthquakes, that should be all you need. If you want them more firmly attached to one another, a few screws should do, slotting the screw holes if there will be any cross-grain expansion issues.

[Russell Sansom]

I agree with Frank. I can't quite picture your chest, but is there some reason you don't simply use dowels?