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This is my first time making cabinet doors with inset glass. The width of the doors will be about 18 1/2" and the height will be about 30". These are shaker style doors with a single middle cross piece. I am using 3/4" poplar for the wood. I will be routing a rabbet for the glass to sit in. The glass will be 1/8" thick.

The customer would like the stiles and rails of the door to be as thin as possible. My question is how thin can I make the stiles and rails and still have enough strength to support the weight of the glass and be a fairly sturdy door? Ideally she would like 1" wide rails and stiles. But I am starting to be concerned that if the rails and stiles are that thin they won't be able to support the weight of the glass. Is there any sort of formula or guide used to determine this type of thing?

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    Wood if often stronger than we give it credit for, and with poplar many will be concerned that going too thin will yield a weak door and that's certainly something to factor in. But there's an additional issue to concern yourself with that is probably more important and that's the stability of the stock you use.... and this will mean every piece, since just one piece warping in service could easily affect alignment enough to at least be visible and possibly to cause binding or a failure to fully close.
    – Graphus
    May 3, 2022 at 22:40
  • "The customer would like the stiles and rails of the door to be as thin as possible." I presume you mean narrow rather than thin? This sounds like they're trying to replicate the aesthetics of something made in metal, and trying to do a like-for-like substitution rarely works out well. I've seen the results of attempts to push wood beyond what it's up to and the results are never pretty.
    – Graphus
    May 3, 2022 at 22:49
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    "Also will 2 hinges be enough to support the weight of the doors? Or should I think about 3 hinges per door?" Separate query, should be its own Question. But I can tell you now, it's a little too open-ended because, well, what type of hinge? Even plain ol' butt hinges are more than up to it if they're large enough, and the hold of the screws is sufficient. With 3/4" poplar this would be my major concern (because you're forced to use 1/2" screws, right?) rather than the hinge itself, since individual hinges are often rated for more than the weight of the entire door....
    – Graphus
    May 3, 2022 at 22:52
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    Best to make test piece if you have doubts! Formulas are available for building/engineering, not for wood at this scale. I think doors can support glass no problem if joinery is good, what joints do you plan? Weak point maybe screws.
    – Volfram K
    May 4, 2022 at 9:01
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    I've removed the 2nd question about hinges because it really needs to be a stand alone question and much more info is needed to have a chance of answering that part. Please feel free to ask a second question - nobody will look down on you because it's expected here.
    – FreeMan
    May 4, 2022 at 14:41

2 Answers 2

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Nobody can answer this definitively unless they’ve tried it (I haven’t, for the record), but every time I get an edge case like this, I think to myself, “self, have I ever seen this in the wild?” Then, after I answer myself in the negative, I wonder how come?

One answer is that trades are notoriously conservative because they don’t want their work to break and cause a callback that’ll cost them all of the profit from the job.

Another is that we might lack imagination.

Anyway, to 1” rails: I think it’s insane. All the contractual clauses in the world dumping liability onto the client won’t matter a bit when they drag you on every review site they can find because “your” cabinet doors sagged and one even broke, sending shards of glass across the floor.

Maybe metal is the way to go. It’s strong enough.

Ps, use tempered glass.

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    "Nobody can answer this definitively unless they’ve tried it" I don't think even then, cos wood varies. Out of curiosity, would you be as hesitant if the stock were RS white oak or ash?
    – Graphus
    May 4, 2022 at 0:49
  • I’d still run away from ash or oak because I’d fear the strength of the joint. (My best would be a haunched tenon — say, 3/8” by 1/4” thick — only leaves 5/8” of weak grain at the bottom/top of the stile.) I suppose a big dowel could be used, but that’s got it’s own issues. May 4, 2022 at 13:13
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    I see no reason one couldn't go with bridle joints, or full-depth tenons given how some thin doors in cherry are made, although to be fair they're not typically holding the weight of glass, even at 1/8" that could be quite a bit although we're guessing — just realised as I typed this we don't know the other door dimension.
    – Graphus
    May 4, 2022 at 14:41
  • Truthfully, a bridle joint hadn’t occurred to me. I might try that (with two pins) on a personal project, but I’d still be too risk averse to ask for money for that. (And I should have specified in my earlier comment that I was thinking of a full depth tenon.) May 4, 2022 at 20:24
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You asked two questions, one about width of the rails and stiles, and one about hinges.

Rails and Stiles: 1" will be ok, although minimal, if you use appropriate joinery. If it were me, I would (and have) go with 1 1/4". In either case, coped joints (which in your case would mean the tenon on the rails being the same depth as the groove for the glass) will not be sufficient long term for these doors. Use a full depth tenon. That will give you close to 2 in2 of long grain glue surface on each corner joint, which will be sufficient. I would take care though, to make sure you've got straight grained wood with no to minimal short grain run out on both the rails and stiles.

Hinges: You don't indicate what kind of hinges you intend, so this is a bit harder to answer. The failure modes are quite different for, say, butt hinges, vs offset hinges. Since you're mimicking Shaker design, I'm going to guess you plan to use butt hinges (I also doubt you'd find offset or concealed hinges that would fit 1 1" stile). Two will do if you use good quality, properly sized butt hinges, but you want to pay attention to getting the screws right. You want maximum holding power on the top hinge. So, use a long screw (you should be able to accommodate 5/8" for sure, and probably 3/4") and drill the pilot holes to the recommended size and length for the screw. Finally, since you're dealing with a wood with relatively poor screw holding power, you could consider reinforcing the holes. Michael Fortune has a nice video on Fine Woodworking showing how to do this.

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  • +1 for the joinery and stock tips in the first paragraph.
    – Graphus
    May 4, 2022 at 14:32
  • 3/4" screws in 3/4" material with mortised-in hinge flaps? The screw query needs to be asked as a separate Question anyway so we can address that properly there, but since FW's content is largely behind a paywall even with a link to the Fortune article it would be good to précis the tip (superglue?) as per SE guidelines.
    – Graphus
    May 4, 2022 at 14:33
  • FYI- I've removed the "hinge" portion of the question because it should really be a stand-alone question. You may want to edit that out of your answer. You might want to store the text because it may be applicable (with more detail to address the specifics I hope the OP will add) to his new question.
    – FreeMan
    May 4, 2022 at 14:42

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