Best method of making accurate bevels.
- Thread starter simonms
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MikeG.
Established Member
simonms":9rvke60p said:
That can't work. The principle of a shooting board is that the plane runs along a piece of wood as a guide, most of which it planes away to the depth of the blade protrusion. Unfortunately, you've put a piano hinge on the critical bearing surface/ edge.
Alluvium is loose sedimentary deposits. It's a geographical/ geological term, not a workshop term.Yes I see what you mean, am new to shooting boards so sorry for the glaring error.
Any ideas on proper implementation? I received this advice but struggling to picture it,
I would be looking more at a shooting board where you can change the angle the board is held at. Think of a door held to a door frame with two hinges, lay the door frame on your bench and the plane runs along this piece of wood on its side so the blade presents itself to the wood slat that you clamp to the door which can tilt to any angle. All you have to do is change the angle of the door to suit the angle on your slat. There are electronic gadgets these days that measure angles, even some phones can do it, or use a sliding bevel. This would work for long and short slats and would be very accurate, as the wood is held securely and all you have to do is run the plane on its side along the frame.
Any ideas on proper implementation? I received this advice but struggling to picture it,
I would be looking more at a shooting board where you can change the angle the board is held at. Think of a door held to a door frame with two hinges, lay the door frame on your bench and the plane runs along this piece of wood on its side so the blade presents itself to the wood slat that you clamp to the door which can tilt to any angle. All you have to do is change the angle of the door to suit the angle on your slat. There are electronic gadgets these days that measure angles, even some phones can do it, or use a sliding bevel. This would work for long and short slats and would be very accurate, as the wood is held securely and all you have to do is run the plane on its side along the frame.
Jacob
What goes around comes around.
Just tilt the blade in the plane?
custard
Established Member
Jacob":1qeuosv4 said:
Yes, that's what I'd do. Make a little angle setting reference piece out of 6mm MDF, use run/rise to set the angle and you can hit a tenth of a degree. Then use that in conjunction with the lateral lever on the plane to set the required angle.
You just need to make sure you've honed your plane blade so the cutting edge is dead straight.
It's a great idea but as the curve tightens I have worked out I will need up to 6-7 degree bevels hence the shooting board idea. So essentially need to be beveling between 1 and 6 degrees.
Thanks for the input so far, much appreciated.
Thanks for the input so far, much appreciated.
MikeG.
Established Member
simonms":2jfzki61 said:
Hang on.......are you saying that the curve is variable? It isn't a continuous radius? In which case, why the need for accuracy?
Sorry Mike, not understanding this, surely any curve would require accurate bevels for it to adopt it desired form. Do you mean that you could essentially be off with the first bevel and adjust for the following?
MikeG.
Established Member
You have the advantage of knowing what it is you are trying to achieve. We're just guessing. If we had a drawing, and the question was "how do I build this?", then all the guessing would be done with, and you'd be getting some useful opinions and ideas. Certainly coopering was "offer up and adjust", rather than some mechanical pursuit of angular perfection.
Yes, annoyingly it does need to be seamless hence the need for nice tight joins, certainly a jig will be made once I have forged an idea of the best approach, I like the idea of an adjustable shooting board so any thought on implementation would be gratefully received or indeed suggestions why it might not be optimal or other ideas.
I am still wondering, due to the small bevels whether the rail saw might work ok, maybe have to tidy up with a plane afterwards.
I am still wondering, due to the small bevels whether the rail saw might work ok, maybe have to tidy up with a plane afterwards.
Jacob
What goes around comes around.
Now can see what it's supposed to be like!
I'd suggest doubling up your 63mm or more to make wider boards, planing it over thickness, jointing as best you can over a former (place one piece on, adjust edge of next piece to fit), glue, then shape the inside and outside surfaces with planes, nicely cambered for inside curves, and/or scrapers etc.
i.e. a woodworker's approach, not a machinist's or engineer's. Join it first then finish shaping it, rather than vice versa.
I'd suggest doubling up your 63mm or more to make wider boards, planing it over thickness, jointing as best you can over a former (place one piece on, adjust edge of next piece to fit), glue, then shape the inside and outside surfaces with planes, nicely cambered for inside curves, and/or scrapers etc.
i.e. a woodworker's approach, not a machinist's or engineer's. Join it first then finish shaping it, rather than vice versa.
MikeG.
Established Member
Those curves are so shallow they're in danger of it looking like a flat board gone wrong.
What's the imperative for the curve being right, exactly as drawn? I mean, what if you were to make the bevels first, do the coopering, and glue that lot together, then shape the other pieces (top, bottom, whatever) to suit?
What's the imperative for the curve being right, exactly as drawn? I mean, what if you were to make the bevels first, do the coopering, and glue that lot together, then shape the other pieces (top, bottom, whatever) to suit?
Thanks guys, well without going into the subject of exponential horn flares all I can offer is the the curve has to be constructed with this exact amount of staves and be as close to the drawings as I can possibly make them.
What I am after is the best method of accurately cutting these bevels. I would be happy to experiment with my own ideas on how this might be done but thought it a good idea to ask the experts. My habit with woodwork is I achieve good results but always take the long way round so I am trying a different approach and asking for help.
My intention is to make the all of bevels and check they adopt tight joins over a jig, glue up then shape them.
What I am after is the best method of accurately cutting these bevels. I would be happy to experiment with my own ideas on how this might be done but thought it a good idea to ask the experts. My habit with woodwork is I achieve good results but always take the long way round so I am trying a different approach and asking for help.
My intention is to make the all of bevels and check they adopt tight joins over a jig, glue up then shape them.
MikeG.
Established Member
I don't understand why you don't engage with the suggestions. But, as you don't, you can carry on without my input.
Right, moving on, it might be an idea for me to explain that I am copying a pre existing design, the drawings demonstrate the conclusion of my back engineering process. I am sure many other and possibly better ways of constructing this curve might be possible and the suggestions have all been very welcome and interesting but I am hemmed in.
Jacob
What goes around comes around.
You do realise that each bevel is theoretically going to be different due to the free shape of the curve - varying by tiny fractions of a degree?
The idea that you could cut each of these perfectly and then fit them together is a non starter.
Are you looking at an original item to copy? If so I suggest looking a bit closer - your "reverse engineering" looks more like a wild and incorrect guess as to how it was, or could be, made.
What you could do is plane all the bevels to the same angle in such a way that they'd close the gap on the front but remain open to varying degrees on the back.
One very traditional and simple way to make up a curved surface is to kerf the back of the piece and then bend it around a former. Commonly seen on the bull nose bottom step of a stair riser - may turn through 180º in quite a tight radius.
In your case you could make up the board flat (easy) then kerf the back to a few mm from the front with as many kerfs as you need, then bend it to fit a former.
The idea that you could cut each of these perfectly and then fit them together is a non starter.
Are you looking at an original item to copy? If so I suggest looking a bit closer - your "reverse engineering" looks more like a wild and incorrect guess as to how it was, or could be, made.
What you could do is plane all the bevels to the same angle in such a way that they'd close the gap on the front but remain open to varying degrees on the back.
One very traditional and simple way to make up a curved surface is to kerf the back of the piece and then bend it around a former. Commonly seen on the bull nose bottom step of a stair riser - may turn through 180º in quite a tight radius.
In your case you could make up the board flat (easy) then kerf the back to a few mm from the front with as many kerfs as you need, then bend it to fit a former.
