What type of router cutter do I need to make this?

[Deleted member 174758]

Cutting a bullnose requires a cutter which works the whole edge, so it can't be done properly with a bearing guided cutter 9which will produce a step). Best done with a router in a router table and a fence

 

[Yukster]

Cutting a bullnose requires a cutter which works the whole edge, so it can't be done properly with a bearing guided cutter 9which will produce a step). Best done with a router in a router table and a fence

Maybe I should find someone to do this for me because I don't have a router table.

When I contacted Axminster tools they said this cutter come with two bearings, one that creates a step or an ovolo cut and one that produces a bullnose cut with no step. Trend and Wealden tools also sell the same cutter that does both

 

[big-all]

my suggestion off course won't give a true bullnose as in half a circle but is near enough i feel in this instance with lower tool requirements ??

you can buy all sorts off mouldings
https://duckduckgo.com/?t=ffsb&q=wo...//www.wooduchoose.co.uk/uploads/products2.jpg

 

[Deleted member 174758]

A bullnose cut is a complete curve with no flat on it. If you want to produce one of those you DON'T want a cutter with bearings at all - those are designed to run against an edge - and on a bullnose edge you have nothing to run against! The cut needs to be made against a fence, as in a router table and this is the type of cutter you need

(That's a Wealden cutter from this page, the dimension "A" needs to match or be larger than the thickness of your boards). The fence needs to be set so that it lines up with the deepest point of the cutter and this type of cutter is too dangerous to use on a freehand router, fence or no fence

If you put a bearing on router cutter it always needs to have a flat surface to run against - at cannot run against a curved surface such as an already radiused edge without creating a quirk (step), so you have to compromise and end up having to use a smaller radius on each edge and leaving a flat in the middle. Despite what the sales burke at Axminster said, that is NOT a bullnose, it is two radiused edges (which is what you get when the guy telling you this either doesn't kow or doesn't care what he is gabbing about - I hate idiot salesmen). So on a 22mm thick board you'll struggle to get more than about a 6mm radius on each edge as the bearing is always a couple of millimetres below the bottom of the cutter and needs 3 to 4mm of surface to run against. This sketych should explain the difference, the edge on the left is what you can achieve with a radius cutter and bearing, the edge on the right is a true bullnose:

The left side may well be OK for you and is doable at home - but it ISN'T a bull nose. If you attempt to use a 10mm radius bearing guided round-over set on a 22mm thick piece of timber to make a true bullnose you'll end up with something like this:

That is exaggerated a little bit, but the step is more than 0.5mm and really noticeable unless you want to plane and sand it out

BTW, look at the tooling catalogues and this is the sort of cutter that they call a bull nose cutter:

Note the lack of bearing...

 

[Yukster]

Thank you very much for taking the trouble explaining this. I was wondering myself how a cutter with a bearing could work for me and your explanation confirms that it can't, which makes perfect sense. Unfortunately, the Wealden cutter where dimension "A" matches or is larger than the thickness of my boards (25mm) is out of stock. The next size up is 32 mm which might be too big.

With this equivalent cutter that is sold by Axminster https://www.axminstertools.com/axca...tter-d-38-1-x-32-r-11-1mm-s-1-2-12-7mm-666192 that has a radius of 11 mm, would its dimension "A" be 22 mm?

 

[Deleted member 174758]

With this equivalent cutter that is sold by Axminster https://www.axminstertools.com/axca...tter-d-38-1-x-32-r-11-1mm-s-1-2-12-7mm-666192 that has a radius of 11 mm, would its dimension "A" be 22 mm?

Yes, but it doesn't need to be exact. Providing the radius is equal to or more than half the thickness of the material it will produce an acceptable result. To help you visualise the difference in how they look the 11mm radius is on the left, a 16mm radius is on the right in this sketch (on 22mm stock):

Those are quite big cutters and really do need to be used on a router table, however I often make up site router tables by taking a piece of MDF or plywood, something like 700 x 400mm or larger will do, screwed to a couple of studs and supported on a pair of trestles. Two holes are drilled through the sheet material - one in the middle large enough to take the largest cutter and a smaller one more or less in line to take an M8 coach bolt:

The router is fixed to the underside by screwing through the base into the plywood after mounting the cutter. The router cutter is plunged downwards (it is upside down) through the hole to the approximate position and locked off. The table top is then inverted and screwed to a couple of studs which are supported on trestles. A fence is cut from a piece of 2 x 2 or 3 x 2 PSE softwood and an 8mm hole drilled through it near to the end. This is fitted on to the table with a coach bolt, washer and wing nut so that it can pivot. It looks a bit like this:

The router is started and the fence is very slowly pivoted into the cutter to form a pocket. Pivot the fence out, turn it off and adjust the cutter to the correct height then recut the pocket. Set the required depth of cut by pivoting the fence and clamping the loose end with a G-clamp, QR clamp or even a screw. You now have a basic router table. Ideally you need some form of ON-OFF (or better NoVR) switch which is easily accessible to turn the thing on and off without the need to reach beneath the table. You also need a push stick so that your fingers never go near to the cutter. This will work for doing long edge bull noses. For short edge ones you'll also need a "squaring board" or pusher - basically a piece of rectangular MDF again with a handle screwed on top (can be a lump of wood) which you can use to push the timber across the cutter - necessary because you are working end grain and want to avoid kick back

Not the greatest sketches, I know, but done quickly and hopefully with enough detail to show my intent

 

[Yukster]

Thanks. You're a star. The sketch is pretty clear. I have a foldable black & decker work bench so I'll use that as a base and make that router tabletop as you suggest.

 

[big-all]

b&d workmate may not take a large router as the jaws only open about 5 1/2"/140mm

 

[Yukster]

b&d workmate may not take a large router as the jaws only open about 5 1/2"/140mm

My workbench jaws can be moved to make the opening wider so that should be fine.

 

[Deleted member 174758]

Ideally I'd aim for a work surface height at 800 to 1000mm above the floor) or more or less the height your wrist is at). I find that Workmates are fairly low, at least for my 6ft 2in frame, and that when I made up a router table for one of those years back I ended getting tremendous back pain using it, so I made up a box, a bit like this:

Two extra lengths of sheet material as "legs", two bits of 2 x 2 to fix the top to the ends and a 2 x 1 front and back to tie it together. Loads of other ways to do this. Note the push block for end grain routing (in green)

 

[Yukster]

Ideally I'd aim for a work surface height at 800 to 1000mm above the floor) or more or less the height your wrist is at). I find that Workmates are fairly low, at least for my 6ft 2in frame, and that when I made up a router table for one of those years back I ended getting tremendous back pain using it, so I made up a box, a bit like this:
View attachment 255915

Two extra lengths of sheet material as "legs", two bits of 2 x 2 to fix the top to the ends and a 2 x 1 front and back to tie it together. Loads of other ways to do this. Note the push block for end grain routing (in green)

You're right, b&d workbench is a bit low. Your design looks the bee's knees but I don't have the space to store it. That's why I thought of the b&d bench as a base because it's foldable. But I take your point it's not ideal.

My next house will have a workshop so I'll have space for a router table and more

 

[Deleted member 174758]

That's really just a quick and dirty design, a result of the site-based nature of most of my work these days. There's no reason why you couldn't screw it together and unscrew it and store it flat between uses

 

[Yukster]

That's really just a quick and dirty design, a result of the site-based nature of most of my work these days. There's no reason why you couldn't screw it together and unscrew it and store it flat between uses

I guess so. I'll give it a go. Many thanks