Rounding to top edge of coffee table

[MatthewRedStars]

If you imagine that the bevel on the long grain rotates from being square (90 deg) to 45 deg and onwards towards being as flat to the panel as possible (the panel becomes infinitely thin).... then it seems correct that the "potential breakout tendency" becomes exponentially more favorable against a linear "angle-to-breakout" ratio as you increase the angle of the bevel.

This is hard to explain in words but a long grain bevel will reduce breakout when planing end grain. The bigger the angle the better as the panel becomes "thinner" and the planing angle when the blade exits the work becomes closer to parallel with the planing direction.

 

[bugbear]

If you imagine that the bevel on the long grain rotates from being square (90 deg) to 45 deg and onwards towards being as flat to the panel as possible (the panel becomes infinitely thin).... then it seems correct that the "potential breakout tendency" becomes exponentially more favorable against a linear "angle-to-breakout" ratio as you increase the angle of the bevel.

This is hard to explain in words but a long grain bevel will reduce breakout when planing end grain. The bigger the angle the better as the panel becomes "thinner" and the planing angle when the blade exits the work becomes closer to parallel with the planing direction.

Yes, I understand that. In effect the grain is supported, albeit incompletely. It's the same sort of mechanism as a skew blade on a shooting board reducing spelching.

But doing the short side first, the spelching occurs in waste, and doesn't matter at all, whereas in the long side first approach the spelching is merely reduced in the way you describe.

BugBear

 

[Jacob]

.....
Simply claiming you're right (repeatedly) isn't a discussion Jacob.

I'm challenging your idea, and I'm providing a reasoned argument. Prove me wrong! I might change my mind, if presented with evidence or reasoning.

Or you could grab a 6x6x0.5 inch bit of board (which might be something some a plant stand top), grab your favourite moulding plane, and try to work a moulding all the way round. Try it!

BugBear

Because I've done it often I know it works.
But feel free to do it your way. :lol:
NB it's not guaranteed - it just reduces the likelihood of spelching. If you do the end grain edge first you can spelch out great lumps - too big to remove when you do the long edge.

PS MatthewRedStars has got it I think. It's about the dihedral angle of meeting planes and what is effectively a skewed cut. It'll vary of course, according to shape, material etc etc.

 

[bugbear]

.....
Simply claiming you're right (repeatedly) isn't a discussion Jacob.

I'm challenging your idea, and I'm providing a reasoned argument. Prove me wrong! I might change my mind, if presented with evidence or reasoning.

Or you could grab a 6x6x0.5 inch bit of board (which might be something some a plant stand top), grab your favourite moulding plane, and try to work a moulding all the way round. Try it!

BugBear

Because I've done it often I know it works.

With straight blade planes you can reverse. I gather? Do you own a working moulding plane or panel raiser? Because if you don't you haven't tried what I'm carefully describing.

I've done it, and I know it works.

Argument is an intellectual process. Contradiction is just the automatic gainsaying of anything the other person says.
- Monty Python

BugBear

 

[Jacob]

First time I used a moulding plane was to cut a moulding around the top of my first solid block made box for sharpening stone. That's when I was told about "the method" - about 40 years ago.
Done it since many times but most often I've been doing raised and fielded panels (100s) with plain flat bevels - either planed straight on or cut over a TS and finished by hand plane.
I've also rounded off the edges of many other boards - bread boards, table tops etc.
There is no argument.

 

[bugbear]

If you imagine that the bevel on the long grain rotates from being square (90 deg) to 45 deg and onwards towards being as flat to the panel as possible (the panel becomes infinitely thin).... then it seems correct that the "potential breakout tendency" becomes exponentially more favorable against a linear "angle-to-breakout" ratio as you increase the angle of the bevel.

This is hard to explain in words but a long grain bevel will reduce breakout when planing end grain. The bigger the angle the better as the panel becomes "thinner" and the planing angle when the blade exits the work becomes closer to parallel with the planing direction.

Of course, this only applies to the classic raised (optionally fielded) panel, with it's low angle. Being a belt and braces overthinker when I did panels for my porch door, I did the end grain first (reasons give already ), AND worked from both ends (because I could) AND used a skew bladed plane.

It went well

As the angle of the worked surface changes from near horizontal (e.g. raised panel) to near vertical (e.g. quirk of a moulding) the reduction effect on spelching diminishes to zero, leaving "end grain first" gazing over the field of victory.

BugBear

 

[Jacob]

...
As the angle of the worked surface changes from near horizontal (e.g. raised panel) to near vertical (e.g. quirk of a moulding) the reduction effect on spelching diminishes to zero, leaving "end grain first" gazing over the field of victory.

BugBear

Yes I think you've got it at last BB!

 

[OscarG]

Just curious, but why wouldn't you use a round-over bit on a router?

 

[John15]

Just curious, but why wouldn't you use a round-over bit on a router?

Thanks for the suggestion Oscar but I did say in my opening post that I don't want to use a router - too noisy and dusty, I prefer hand tools. I've taken the advice of others , and have formed the round-over with a No.4 and sandpaper. Just the buttons to fix and finishing with Polyx hard wax oil.

John

 

[OscarG]

Just curious, but why wouldn't you use a round-over bit on a router?

Thanks for the suggestion Oscar but I did say in my opening post that I don't want to use a router - too noisy and dusty, I prefer hand tools. I've taken the advice of others , and have formed the round-over with a No.4 and sandpaper. Just the buttons to fix and finishing with Polyx hard wax oil.

John

Yeah I did see that, was just wondering why. I do appreciate the noise and dust aspect though! I guess I'm more of the new generation of woodworkers preferring to use power tools (i.e less skilled!).

Lovely table by the way.

 

[John15]

Cheers Oscar

John