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I recently had to rehang a laundry door as it had dropped over the years. As I was squaring up the door and redrilling the dowels I wondered whether the door would be stronger if I drilled and glued all the dowel holes in one pass, or two passes.

What I did was to drill and glue half the dowel holes, and then once dried, drill the other half. I have no data, but I did think that the two pass method could be stronger just using normal PVA glue.

Does anyone have any proof that this is a stronger method/approach to glueing up? My feeling is that it would be due to stresses being distributed.

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If you're doing any sort of glue-up using a PVA and the conditions or pace of work mean that the glue is partially set before things come together and full clamp pressure is applied you are compromising strength.

How much strength and whether it's enough to be significant is entirely down to the specifics of the situation so no predictions are possible.

Factors that will affect this are not limited to:

  • Obviously the biggie is the drying time of the PVA (readers please note this includes both white and yellow forms of "wood glue", they're all PVAs no matter what other name they go by).
  • The ambient humidity – high humidity is a help here.
  • The moisture content (MC) of the wood – dry wood means you have to work faster.

We've got some wiggle room here since glue bonds are so strong, and many applications don't actually require the max strength possible (where the glue joints are stronger than the wood) but I think it's best to always aim for max strength rather than be complacent and have something bite you now, or more likely after a few years when one or more compromised glue joints have loosened after multiple cycles of wood movement. Take note any budding chair makers.

Where strength is critical, do as much as you can in the window where the glue is still absolutely a liquid (not even remotely skinned over) and/or hasn't sunk into the wood (as happens quite quickly on end-grain surfaces as well as similar areas on long-grain surfaces where there's rising grain).

In published projects both in the magazines and on YouTube you'll regularly see larger projects broken up into stages, in part for precisely this reason. Even something fairly straightforward like laminations can be done in multiple steps if there are enough boards involved, i.e. two or three subassemblies are glued, and after those have set they're brought together in a final glue-up.

If you want to do everything in one operation
If for any reason you want/need to get something larger or more complex glued together in one go that is possible, switch glues.

You could try a PVA with a longer open time but you need a different glue type for a really comfortable working period, so you might switch to polyurethane glue or a urea-formaldehyde adhesive. And for a really comfortable, even sedate, glue-up obviously go with an epoxy since there are versions with setting times of an hour or more.

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  • Thanks, your "In published projects.." gets close to what I was expecting. But my question was about a "complete glue up in one operation" but with say half the dowels. Then do another "complete glue up" with the remaining dowels. Would this be stronger than just doing one glue up with all the dowels glued. My logic was that stresses would be relieved in a partial glue up ...
    – User314
    Jun 30, 2023 at 8:32
  • My Answer sought to address this in general terms — that glue-ups are regularly done sequentially or in stages, with a final assembly step — with an emphasis on the adhesive reason you'd choose to. If there are no compromises needed (e.g. the first joint's glue is likely to be partially dried by the time you get to clamping, for whatever combo of reasons) then it makes sense to do it in one go, unless it's too awkward to handle. That shouldn't be a factor for a dowelled door, since the dowels act to hold things in alignment & prevent undue separation as everything is brought together [contd]
    – Graphus
    Jun 30, 2023 at 9:45
  • Okay, got it. Thanks
    – User314
    Jun 30, 2023 at 9:50
  • ...all the dowels are wiggled into place and clamp pressure is applied. The reasons to do things in steps or subassemblies are about ultimate strength but only in as far as sub-par glued joints are concerned, rather than it being innately stronger to do it in two rather than one. If you do everything right there should be no difference (not no discernible difference) between something assembled in one or two goes, because either way all glue joints should actually be stronger than needed — exceeding the strength of the wood around them. There's no need for a higher bar to be set.
    – Graphus
    Jun 30, 2023 at 9:50
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    Perfect. I can't vote you up as I don't have the requirement points but thanks answering. I like the description that the dowels are "wiggled into place" - never thought of it that way
    – User314
    Jul 1, 2023 at 2:22

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