I recently saw a dining room chair at a friends house and, being the curious woodworker that I am, I layed down under it while no one was in the room to see how it was constructed. It had about a 2 and a half to three inch seat rail and the rails were attached to the legs with three pocket hole screws and of course the standard chair blocks that are mitered at each end and screwed into the rail to provide more support.
Does anyone else think hat this joint may be too weak or am I alone here. I tend to like a bit of a stronger joint (mortise and tenon) for my chairs. Am I wasting my time in taking the time to cut all those M and T’s. Could I be done in much less time while not sacrificing any strength.
I am thinking of making a chair each way and abusing them to see which breaks first.
Any thoughts?
Replies
Hi shopmate ,
There certainly are applications where pocket screws work great , chair frame construction is like a torture chamber for any wood joint .
Some lower end furniture is made in kd frames , panels , sides ends , etc. pocket holes work on some because they are stationary with less weight and stress then a chair .
The screws offer so little in the way of structural integrity , perhaps up through the apron rail to attach the seat ?
just imo , stick with the more traditional types of joints on chairs .
dusty
I do not have experience with pocket holes in chairs, but I have some experience with chairs. I would be interested in hearing some real-world results with pocket screws.My experience is that screws, nails and staples in chair do more harm than good. Causing difficulties with disassembly aside, the presence of these in chairs is almost always accompanied by split wood. My theory is that it creates a leverage point and concentrates forces in a small area that in a wood joint would be well-distributed.Chairs need to be highly engineered as pound-for-pound carry more weight than almost any other piece of furniture, and in addition they are regularly moved under weight (slide up to a table or away from tables), racked under weight (leaned back in) and generally abused (climbed on, dropped into (ever see an obese person get 2/3 of the way seated and then drop?), and pressure applied to stretchers) in the normal course of usage.The other advantage for mortise & tenons, even for the lowly and not that strong dowel joint, is that you can take it apart and re-do it. I think if a pocket joint screw failed or weakened after a number of years, you have trash.
Yes, make your test chairs. This exercise will teach you more than this forum could in a year of daily reading.
Well, I'm not gonna make an entire chair just to break it, perhaps a little mock up of just the legs and chair aprons. I undoubtedly will stick with the M and T joints, but it is interesting to see how well pocket hole screws really hold and if they stand up to the hype. I'll get back to you.
This chair needn't be fancy. It doesn't even need to be comfortable..... just four legs a seat and a back. You suggested that you might do this. I think its a good idea because I've done similiar tests myself. You could complete this "project" in an afternoon. Then you would have some real knowledge. If you don't want this, then keep asking here. You'll get a bunch of people's opinions on how pocket screws aren't fine woodworking and don't belong in a serious woodworkers kit. Meanwhile you won't learn anything.
Popular Woodworking did a test in their Dec. 2005 issue where they tested assorted joinery by dropping anvils on them. The mortise and tenon and pocket screw joints fared about equally well as far as strength was concerned but there was concern about longevity of the pocket hole screws ability to hold over repeated cycles of shrinking and swelling. They also thought the mortise and tenon would be easier to fix in the event of a failure.
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