I have a new woodworking toy which has lost an adjuster crank lever. There is a short rod about 10mm dia with a flat on it. I need something to go on said rod and engage with the flat. Anyone know what such a thing might be called? I don’t really want to just use a round tube with a grub screw, as the flat will get damaged. I need to put a fair bit of torque through it, so it needs to be a good fit.

Would be grateful for any tips!

It’s a bit like a cottered crank bottom bracket – smaller, obviously, but some kind of crank handle with a hole for a cotter pin might be what’s needed.

Alternatively, could you file a flat on the opposite side? Then use a open ended spanner.

If filing is not an option then stilsons might work. Probably neeed a small pair though and they might chew up the rod.

What tool out of interest?

Ah yeah, a cotter might work. Thanks! It’s a thickness planer, and this is the bit which you wind to adjust the table up and down. It’ll be used quite regularly, so needs a proper tool rather than stilsons I think. Will see what sort of cottered crank I can bodge…

As s temp tool a round bar with grub screw, as you mentioned, but with a shim between the flat and grub screw to prevent damage?

Why not make a handle? A bit of steel bar, drill out most of the waste, then use a needle file to remove the rest. A few squids and an hours work.

Looks like you need something like a gas control knob – like you’d find on a cooker. Like this

http://www.partmaster.co.uk/product.pl?pid=3770090

Other way is to treat it like a shaft with a flat – make a tool with a 10mm bore, file a flat inside the bore, wedge in a square or rectangular key against the flat.

Was it a handwheel like this?

If so, a key fits into the slot in the wheel and engages the flat on the shaft. https://en.wikipedia.org/wiki/Key_%28engineering%29

If its a low torque application, a set screw could also be run through the wheel to engage the flat on the shaft.