Thread: What plane to use to make 3/4 inch half round groove

Tom, you need a "Round" plane.



These are typically sold in pairs ... Hollows and Rounds.

Get a used one cheaply on eBay or a second hand dealer. Or spend a little a get a beaut from HNT Gordon.

Your Stanley is another way to go. You need to look up "fluting" blades.



Regards from Perth

Derek

Sorry double post

Ciao
This blade is 3/4".
It is for Stanley 45 or 55, I don't know if it could fit your 3-052: the blade notch seems to be on the correct side altough the shape maybe it's not correct? However you can use this as example for make one yourself.

Orig. 3/4 Inch Fluting Iron for Stanley No. 45 or 55 Plane- No. 38- mjdtoolparts | eBay

Giuliano

I have a #12 round currently for sale. The #12 is about 1" wide at full depth of cut but it might work for a 3/4" shallow cut.

Various wooden planes, simple and complex profiles

I've never used one, so don't know if they can manage a cove of 3/4", but a core box plane is the one to cut a perfect half-circle. As was pointed out to me in a post a couple of years ago, the blade of a round is 1/6th of a circle, so if you simply hold the plane straight & cut 'till the edges of the blade are level with the surface, you'll only have part of a semi-circle.
Of course, for the OP's purposes, a perfect half circle isn't necessary, rope is compressible & could be fitted to a groove that was far from an exact semi-circle, so your groove doesn't have to be perfect. A modified plough or moulding plane would be easier in some ways because you will have a fence to guide it, but the bare blades in these things don't handle uncooperative grain directions well, so you might need to switch sides with the fence if you hit any 'uphill' grain & some ploughs won't allow that. I think I'd use a combination of plough to establish the sides of the groove, then clean it out with a round. A #12 has a 3/4" radius, but I read it that the groove needs to be 3/4" diameter, so possibly a #6 is the one you want?
Cheers,

The problem with the suggestions so far is there is an assumption you are dealing with a continuous straight piece of material. A gunwale -- for anything other than a barge -- is, by definition, not straight. It follows the profile of the deck edge.

You might come across a coach maker's hollow plane of the right size that could do it but they are usually more expensive than a common cabinetmaker's hollow.

Originally Posted by markharrison

The problem with the suggestions so far is there is an assumption you are dealing with a continuous straight piece of material. A gunwale -- for anything other than a barge -- is, by definition, not straight. It follows the profile of the deck edge....

Actually, Mark, I was picturing a curved piece, which is why I was talking about hitting "uphill" grain, but I certainly didn't make myself very clear. I reckon a long curve could be managed with a regular plough, maybe with a wider than normal fence to keep it registered, if necessary. It wouldn't be all that hard to cobble up something like a coachmakers plough, if you used an open-side design like this one, & for a one-off job, the fence could be simplified & fixed, you wouldn't need to make it adjustable.

Another way to tackle the job would be to use a scratch stock. If you removed the bulk of the waste with a plough, it wouldn't be too huge a task for a scratch stock to finish it off if it's a reasonably crisp piece of cedar - some cedar is too soft & furry to scrape well. And I'm picturing a smallish boat here, if it's a 35 footer, I think I'd be more inclined to burn electrons rather than calories....

Cheers

This sort of thing is what I think I'd be making for it . With the correct shaped sole .

Pair of Tailed Coach Makers Planes | eBay

Their a bit rare these Coachmaker types .

I wouldn't be using a fence either . Just gauge with finger and pencil or a marking gauge, three lines and take out the center one with a V groove or a gouge so the plane tracks down the middle to start it and adjust out to the outside lines as you go . The plane needs to be narrower than the finished groove that you want . You check progress with a accurate cut out of what you want in mild steel sheet or tough cardboard or Plywood . And give a final finish to the shape with a proper small curved scraper made from saw blade .

Here's some more planes .

Vintage Tools -
COACHMAKER’S PAIR OF MATCHED PLANES

Rob

I've seen a bloke assemble a scratch plane out of a 3/4" round nose turning chisel just clamped to a block of wood - he was using it to put a circular half groove into the edges of a pieces of wood that were the fronts of the drawers - the groove was located at the bottom edge as a sort of grab point.

Thank you all for our informative replies. I think my best option will be to get a 3/4 rabbet plane and round up the sole and iron to a half round. I can then ad a piece of timber to the side as a depth stop.

If anyone has an old cheap one for sale I’d be interested.


The gunwale is for a 24 foot boat, the gunwale will be roughly 1” by 2”. The majority of gunwales/sheer mouldings/sponsons are shaped with straight stock scarphed together to get the required length. Then bent around the boat and edge-set to the sheer. Sometimes using steam.