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I've been looking into using dowels for joints in a project of mine.

As I've lead a sheltered life, I have pretty much only seen dowels in this "ribbed" style.

However, as I'm planning to use through dowels (so that I don't have to massively up my drilling accuracy game), I'm looking for longer dowels, and I found these smooth wooden rods, which Wickes call dowel mouldings.

I understand the ribbed dowels: good surface area for glue, the ridges grip the hole when hammered in. All in all a good way to strengthen joints.

The smooth dowels on the other hand are longer, can be cut to length and so are easier to use for me. But they don't have the extra features which I presume give stronger joints.

So my question is: will smooth dowel do as well for joinery?

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    Did you have a poke around in the old Q&As here since your first Q? We have an extensive number of previous Answers here that mention dowelling, and quite a proportion of them concern through-dowelling which naturally makes use of what you might term 'non-joinery dowels', i.e. basic smooth dowels. Prior to machinery-made dowels ALL dowelling was done using basic dowels, so as you can imagine they have a proven track record. Incidentally you can quite easy make your own without having a lathe, also covered in one or more prior Answers.
    – Graphus
    Commented Dec 18, 2021 at 0:25
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    With commercial dowels you might read that the flutings are created by compression, rather than being milled in, and the idea is that the flutings swell back up and cause an even tighter hold in the holes once exposed to the water in the most common glue used, some type of PVA. But I've seen many dowels from inside joints where there's no apparent change in the fluting, so a nice theory but it doesn't bear out in practice. [Incidentally similar thing with compressed biscuits (also commonly made from beech) which almost always seem to retain their waffle texture after being wetted with glue!]
    – Graphus
    Commented Dec 19, 2021 at 10:03

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Dowels for joints I think are usually called fluted or grooved.

Fluted dowels are usually made of hardwood and the plain dowel you link to is made of pine. Not equal. For the same diameter hardwood is much stronger than softwood. Also easier to get a smooth result on hardwood end grain.

I understand the ribbed dowels: good surface area for glue, the ridges grip the hole when hammered in.

No.

All dowels in joinery should be a tight fit, where taps from a mallet or hammer must be used to fully insert them. So functional surface area for glue is much larger for plain dowel unless you use gap-filling adhesive such as epoxy or Aerolite. Using PVA glue, with fluted dowels only the tops of the grooves touch the side of the hole to form a strong joint, a reason modern dowels often fail with white or yellow carpenter's glue.

Grooves allow air and glue to come out from the hole so dowels don't bounce back when hammered in! Or force glue out through a minor defect in wood being joined :(

If you don't want to make your own, plain hardwood dowel is available in a range of species, one source in the UK is G&S Specialist Timber. Prices seem reasonable for 1m lengths.

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