Thread: Mat's Split Top Roubo

Originally Posted by Pac man

Matt the recess for my acetal bushing was square.No doubt an earlier version.
I used a plywood template slightly oversized to suit the router guide bush.
Can you use the same method with an oversize circle in plywood ? say with a 75 mm forstner bit

the new bushing is ~63mm dia. circle, as can be seen in the diagram above.

I think a 70mm holesaw bit would work for a template, only $30 from the crap green box, think I'll just go that route.

63mm is awfully close to 2 1/2 inches, and being a US product, I'd expect that's what the nominal diameter of the bush is, so why not use a 2 1/2" saw & do it directly? Mark the depth on the side of the saw, cut down to that depth, then remove the waste with a chisel, or with your router since you seem to prefer your electron burners.. Personally, I wouldn't bother with the holesaw, it's a size you are unlikely to use ever again. I reckon I could have it in place before you get back from the big shed with the holesaw! I'd use the bush as a template & score as deeply as I could around it, then rout out as much waste as I dared, using a small diameter bit for best control. Clean up to the line with an in-cannel gouge, or round the back of an old (narrow) beater chisel to the approximate diameter & use that. With a modicum of care, you should get a pretty close fit, and in any case, it's well out of sight on the assembled vise, is it not?

Cheers,

The recess needs to be bigger than the bushing to allow for alignment. So 70mm is the size they recommend.

As for the router, not to keen on smashing away at this wood. It's pretty damn hard. And isn't the aim of a workbench to be utilitarian, to allow finer work to be done, that's how I see it anyway

Originally Posted by MatMann

The recess needs to be bigger than the bushing to allow for alignment. So 70mm is the size they recommend....

Well, Mat, if the hole has to be oversize anyway, I would certainly use a router.

Originally Posted by MatMann

.....As for the router, not to keen on smashing away at this wood. It's pretty damn hard......

I haven't struck a wood yet that a carbide bit can't take in its stride. The recess in this tail vise was free-hand routed with a 1/4" bit, within a mm or less of the scribe lines, then cleaned up to the line with a chisel: Tail vise bits.jpg
OK, so this recess is straight-sided, but the principle is the same, and the wood is Forest Red Gum, which is up there with the toughest woods I've ever worked with. In this case, the recess needs to be quite accurate, to hold the 'garter' firmly in all directions, otherwise you'd get a very sloppy action, or worse, the garter could disengage from the groove and the scew wouldn't pull the vise back.

Originally Posted by MatMann

.....And isn't the aim of a workbench to be utilitarian, to allow finer work to be done, that's how I see it anyway

Yep, utilitarian for sure, but pride says it should be as neat & workmanlike as you can make it - I think it was Frank Klausz who said we are judged by the quality of our workbenches...

Cheers,