Why no rebates for fitting into a housing joint?

[Fromey]

This comes simply out of curiosity.

In all books and videos I've seen on making a housing joint to fit something like a shelf, it is the full thickness of the shelf that is inserted into the housing. Now if your housings are anything like mine, you often get a small gap showing along the top of the shelf where the housing is just fractionally larger than the thickness of the shelf. (Just my por technique, I know )

So this made me wonder, why not simply cut a small rebate along the ends of the shelf in order to hide any gaps? Only a millimetre or so would be needed and it would not significantly weaken the shelf. Thus, you'd have a crisper edge, just like one gets with the shoulder of a mortise and tenon joint. In fact, the concept is already being used with stopped housings and a notched shelf.

I'm sure it's simple to do, so why does no-one ever seem to mention it (not even Jones; The Practical Woodworker)? Perhaps I've just never read carefully enough and descriptions are right under my nose.

 

[CHJ]

why not simply cut a small rebate along the ends of the shelf in order to hide any gaps? Only a millimetre or so would be needed and it would not significantly weaken the shelf. Thus, you'd have a crisper edge, just like one gets with the shoulder of a mortise and tenon joint.

That is how I was taught, to do it.
And even further to have two short wedged tenons going right through the side panels to hold it together without the use of glue.

 

[AndyT]

I'm sure I've seen it suggested. I'll see if I can find a reference.
But as for the reason why not, it's an extra step which takes extra time and can be avoided. You "only" have to acquire the skill of cutting joints that fit first time!

 

[deema]

+1 for above, alternatively use a sliding dovetail. Easy to make with a router and self locks the shelf into place without any tenons visible on the outside. If cut by hand it's normal only to cut one side at an angle, usually the top. Cut a rebate and then either chop with a chisel or a special dovetail plane. It's also usual to stop the dovetail before the end of the shelf so it's does not break through. For easy of fitting if cutting by hand, the dovetail is tapered from the back to the front so that as you push the shelf in from the back it tightens up in the joint. (If made by hand I would normally make the shelf a little wider and if I made a billy do of the fitting, I can shorten the dovetail at the front edge to allow it to create a tight fit and then adjust the front edge back to the required width. An extra 1/4" makes up for a lot of goes at getting a good fit!!

 

[Phil Pascoe]

When I was at school I had to dovetail the housings on my shelves, so they pull in tight.
Having just seen the above post - we had to dovetail both sides and they were sawn with an angled guide then the waste taken out with a grannie's tooth.

 

[deema]

Hi Phil,
There are Im sure many opinion on the sliding dovetail, I was thought, and the logic seems to hold (pardon the pun) that only the top needs to be dovetailed as the shelf will sag when the weight is put on it. The sag will pull on the top dovetail and lossen any profile on the bottom rebate surface. Irrespective of the bottom profile, it's only actually the bottom edge of the rebate / dovetail that contacts the shelf when under load and acts a fulcrum so the profile becomes less important. However, if it's a dovetail the edge is weaker than if the profile was a standard rebate with a 90 degree angle. Hope this makes sense, I'm not sufficiently competent with a sketch program to draw it.

 

[Phil Pascoe]

Your post makes perfect sense to me. Just because we are taught things, it doesn't make them right.

 

[Jacob]

Good idea in principle ("a good joiner covers his tracks") but if you can't get the straight housing accurate you will probably have the same difficulty with the rebated housing - i.e. the sides may not be perfectly straight so there will be a visible gap anyway. Then, if the sides aren't straight a straight housing will not show this.
Either way yer fooked. Keep it simple.

 

[PAC1]

When I was improving my skills I solved the problem by cutting the groove a nats thinner than the shelf thickness and then sneak up on a tight fit by planing the shelf to fit. It works with real wood. but if you use man made boards it is as Jacob says.

 

[Fromey]

Thanks all for your comments. Indeed PAC1, that is the method Chris Schwarz recommends as an oldie and a goodie.

I'd rather steer away from sliding dovetails for the moment since I'm still trying to master simple housings with handtools only.

CHJ, that's really interesting. It is in fact the type of joint I'm considering making but have also been surprised that I can't find it in any sources I have. My main concern with it will be accurately marking in the mortise on the other side of the housing. The distance is likely to defy cutting gauges, so I suppose one has to extend knife lines from the inside to the outside.

 

[CHJ]

CHJ, that's really interesting. It is in fact the type of joint I'm considering making but have also been surprised that I can't find it in any sources I have. My main concern with it will be accurately marking in the mortise on the other side of the housing. The distance is likely to defy cutting gauges, so I suppose one has to extend knife lines from the inside to the outside.

It's what we had to do after simple lap joints & basic mortise & tenons but before moving on to dovetails.*
All aimed at accurate marking out & cutting I presume rather than the usefulness of the joint.
No electrical powered equipment other than a saw bench and pillar drill, seem to remember the through mortises were drilled through with a forstener bit (waste wood on the rear of course) and then squared up.

* Mine were incorporated in a bedside cabinet, bottom and top shelf, the first dovetails were the two top rails into the sides, these rails carried slots to screw secure the top, presume top designed to hide any messed up dovetails and side engrain. (the only joints where glue was allowed) Good job because only way to easily move cabinet was to pick it up by the top overhang, and dovetails were wrong way round for that.
Raised panel doors had wedged tenon frame joints. (I know one of mine developed a distinct twist over the years for some reason).
Finished that piece and promptly took up a precision mechanical/electronic engineering career path, such are the strange paths our lives are prone to take.