How to make LARGE wooden dowels?

Question

I have a midi lathe, a router and a few other odd's and sods with regards to machines. I need to make some hardwood dowels and they should be 38mm in diameter ( for some wooden screws). What way is the best way to make them? I've tried building a rounder plane and failed, I can't seem to get it to cut...

Answer 1

I've tried building a rounder plane and failed, I can't seem to get it to cut...

That could be troubleshot¹ but actually you don't need a rounding plane to make dowels. They can certainly help achieve a round result but it's quite possible to plane to round using any standard plane².

Hand plane
The process is really very simple: you start with square-section stock held in a planing cradle, pinched between bench dogs or poppets, or using the clamp-in-a-vise trick, then plane the corners (arrises) off to make an octagon. Then you plane those corners off, making the wood 16-sided (hexadecagon), and so on. Although I've seen people go further, I would personally stop at 32-sided (TIL, a triacontadigon!) since this is so close to round. Subsequent sanding can yield virtually perfect cylinders.

This methodology is very old and certainly predates the earliest woodworking guides. But these days we have electricity, and there are about a zillion videos and other guides online on how to make dowels in the workshop using power tools. I exaggerate, but not by much.

Even if there is a lathe available one of the best methods³ for making your own large dowels is on the router table.

Router
The commonest methodology is to again start with square-section stock, running this past a roundover bit to round over each arris in sequence. Do this four times and ta-da, you've created a cylinder.

After running a couple/three test pieces to dial in your setup the process is really fast, actually far faster than even an experienced turner could do it freehand on a lathe, and with much greater consistency. The downside is that obviously this method relies on there being a bit of a suitable diameter; and you're in luck, they do make 19mm roundover bits (with various shank diameters).

There are numerous others but here's the YT vid that first came to mind, A better way to make your own dowels from Stumpy Nubs. This is also one of the best since (as usual) he explains setup so clearly, and doesn't skip over safety considerations. Plus he covers how to sand both smaller and larger-diameter dowels with power assist, although because you'll be threading the resultant dowels I imagine you'll need to do absolutely minimal or no sanding.

In case you'd like to look at other methods as well there's a pretty good overview of many of them in this video from 3x3Custom - Tamar, Making Large Dowels WITHOUT a Lathe // Woodworking Jig // Dowel Maker.

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¹ If the iron is held bevel-down, the first thing I can think of is there's insufficient relief on the cutting edge for the bedding angle. If there too little or no relief the bevel rubs on the wood and the plane won't cut.

² Using a normal bench plane there's the benefit of being able to take advantage of the cap-iron effect, to prevent any bad tearout if the wood used has some unfortunate grain.

³ Safe, fast, and requires no jig to be built.