I agree with Paul. However if you really want to measure, why not take a full width shaving and then measure the thickness at the centre of the shaving, and then the edge, a simple calculation will provide the information. :lol:
Plane Blade Camber
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David C
In Memorium
For the squaring of edges I like a camber which relates closely to the thickness of an average business card.
After shaping on an 800 stone, offer the edge, (vertically) up to a flat surface, and judge the light gap at the edges with a couple of small shims of card. My card is about 10 to 12 thousandths of an inch thick or 0.25 to 0.3 mm thick.
For wide surface smoothing the camber can be much less pronounced, maybe half of the above or even less.
What about thick good quality writing paper as a measuring shim.
Reasonable quality paper is about 0.1mm thick or 4 thou".
best wishes,
David
After shaping on an 800 stone, offer the edge, (vertically) up to a flat surface, and judge the light gap at the edges with a couple of small shims of card. My card is about 10 to 12 thousandths of an inch thick or 0.25 to 0.3 mm thick.
For wide surface smoothing the camber can be much less pronounced, maybe half of the above or even less.
What about thick good quality writing paper as a measuring shim.
Reasonable quality paper is about 0.1mm thick or 4 thou".
best wishes,
David
woodbloke
Established Member
Just to compound the issue :? a camber on a bevel up blade will be much less pronounced in use as the it will be usually seated at 12deg on the plane bed, so in order to have the same sort of effect as a bevel down iron it should have more of a curvature - Rob
Derek Cohen (Perth Oz)
Established Member
I did post information here on cambering a jack blade for a BU plane (in this case my LV LA Jack).
I settled on a radius of 8 1/2".
Here is the profile in the mouth of the LA Jack:
The shavings are about 2" wide and effectively 1/32" thick.
Regards from Perth
Derek
I settled on a radius of 8 1/2".
Here is the profile in the mouth of the LA Jack:
The shavings are about 2" wide and effectively 1/32" thick.
Regards from Perth
Derek
bugbear
Established Member
I'll admit that I rather like measuring stuff. But I think a lot of the drive to measure things like this comes from trying to learn from books and DVDs.
In the DVD, Charlesworth talks about measuring plane shavings with calipers, but at one point later, he just handles the shavings and says "a thou and a half". The measurement is a substitute for hands on experience and feel.
I have no means of replicating the setup proposed by the teacher other than measurement of some sort. Phrases like "very fine camber" aren't useful if they aren't tied down somehow. I've got a "very fine" camber---probably about 0.03 mm. Odate's special concave stones would appear to give a camber somewhat less than 0.06 mm (assuming that the curvature produced on the blade matches the stone curvature). But someone here said 0.25 mm was "very fine". This kind of confusion is cleared up by measurement--assuming I can figure out how to make the measurement.
I calculated that an 8.5 inch radius camber on a 2 1/4" blade bedded at 12 degrees (LV LA jack) would be 0.075 inches (1.9mm). This should perform like a 0.56 mm camber would on a 45 degree bedded plane, and ought to take a full width shaving which is 1/64 inch thick. I wonder why you're seeing 1/32" instead. (I'm not sure I could take a 1/32" shaving that was 2" wide.)
A major disadvantage of evaluating the camber by taking a shaving is that it means the blade must be fully sharpened and placed back in the plane in order to check if I've reached sufficient camber. Seems like this could really prolong the sharpening process. Of course, it does have the advantage of getting directly at the character of the shavings produced. If you do this you don't need to think too hard about your plane's bedding angle. Another issue is that this measure could get distorted by the test piece not being flat.
Can I expect the same blade to work for both wide surface smoothing and for squaring of edges? Will the .25 mm camber work well for both tasks even if a smaller camber might be good for surface work?
In the DVD, Charlesworth talks about measuring plane shavings with calipers, but at one point later, he just handles the shavings and says "a thou and a half". The measurement is a substitute for hands on experience and feel.
I have no means of replicating the setup proposed by the teacher other than measurement of some sort. Phrases like "very fine camber" aren't useful if they aren't tied down somehow. I've got a "very fine" camber---probably about 0.03 mm. Odate's special concave stones would appear to give a camber somewhat less than 0.06 mm (assuming that the curvature produced on the blade matches the stone curvature). But someone here said 0.25 mm was "very fine". This kind of confusion is cleared up by measurement--assuming I can figure out how to make the measurement.
I calculated that an 8.5 inch radius camber on a 2 1/4" blade bedded at 12 degrees (LV LA jack) would be 0.075 inches (1.9mm). This should perform like a 0.56 mm camber would on a 45 degree bedded plane, and ought to take a full width shaving which is 1/64 inch thick. I wonder why you're seeing 1/32" instead. (I'm not sure I could take a 1/32" shaving that was 2" wide.)
A major disadvantage of evaluating the camber by taking a shaving is that it means the blade must be fully sharpened and placed back in the plane in order to check if I've reached sufficient camber. Seems like this could really prolong the sharpening process. Of course, it does have the advantage of getting directly at the character of the shavings produced. If you do this you don't need to think too hard about your plane's bedding angle. Another issue is that this measure could get distorted by the test piece not being flat.
Can I expect the same blade to work for both wide surface smoothing and for squaring of edges? Will the .25 mm camber work well for both tasks even if a smaller camber might be good for surface work?
David C
In Memorium
BB,
Feeler gauges very good.
Card is easy to find and does not rust or buckle, accurate enough for woodwork if measured with callipers?? ~;-)#
Adrian,
Can I expect the same blade to work for both wide surface smoothing and for squaring of edges? Will the .25 mm camber work well for both tasks even if a smaller camber might be good for surface work?
The short answer is yes, though scallops in wide surfaces will be slightly more pronounced than necessary. Some really like this effect.
The Odate plates require some Trigonometry to work out the camber on the blade when viewed vertically, because the blade is offered to the stone at the honing angle and the hollow is measured vertically.................clear as mud I expect.
Any slight camber is better than none, don't worry too much about the precise measurements. All that is affected is the shaving width for a particular thickness setting.
David
Feeler gauges very good.
Card is easy to find and does not rust or buckle, accurate enough for woodwork if measured with callipers?? ~;-)#
Adrian,
Can I expect the same blade to work for both wide surface smoothing and for squaring of edges? Will the .25 mm camber work well for both tasks even if a smaller camber might be good for surface work?
The short answer is yes, though scallops in wide surfaces will be slightly more pronounced than necessary. Some really like this effect.
The Odate plates require some Trigonometry to work out the camber on the blade when viewed vertically, because the blade is offered to the stone at the honing angle and the hollow is measured vertically.................clear as mud I expect.
Any slight camber is better than none, don't worry too much about the precise measurements. All that is affected is the shaving width for a particular thickness setting.
David
bugbear
Established Member
David C":uzfc0vyw said:
I saw a table at Weald and Down that had a massively scalloped, but micro-texturally smooth top.
I made (ahem) extensive enquiries, and finally got through to the maker. I asked about his period evidence, references for this finish.
He said that curved blades used to be used, (we all knew that...), so he just did it.
He had NO (nada, zip, nothing) references for period tables finished that way, just that the tool (a highly sharpened, cambered blade) was capable of it!
BugBear (who was disillusioned)
David C":3q776qhk said:
I used a card rather than getting out my feeler gauges because they're rusting enough without being around all that water. I did, nevertheless, find it somewhat tricky to tell what was going on because if I placed my edge on a (hopefully) flat surface and held it up to the light I would see light shining through everywhere...but eventually more light at the edges. I tried to insert the card, which was about 0.2 mm thick in at the edges. The process required about 20 minutes using a 320 grit shapton stone with a "micro" bevel that was quite a bit larger than I'd like. (It was fairly clear that the 1000 grit was going to take too long.)
I didn't have the time to actually take any shavings and see whether I can make things square and flat. (My last effort ended in frustration when I found that, while making stop shavings, the plane would not cut, yet the wood was still markedly convex. In an effort to blame the tools rather than my technique
, I noted that the sole of the plane (a Clifton #7) seems to be 0.003" concave at the mouth. The Veritas seems to be flatter.) David C":3q776qhk said:
Crystal clear to me. Thanks for pointing this out. I should have realized this right away. My current blade has a 30 degree bevel on it, the Odate plate has a hollow of about 0.065mm, so the size of the camber would be increased by 1/sin(30) = 2, which means about 0.13 mm. Unless the bevel angle is very small, the result is not much different.
I have been considering the "ruler trick" for the preparing the backs of plane blades. This essentially means applying a very slight (low angle) back bevel. In the presence of a camber, does one attempt to make the back bevel uniform in length across the back, which means a curved surface? Or alternatively, one could keep the blade centered (at least in theory) and establish a flat back bevel whose length would vary from small at the sides to large in the center. (This last approach would be easy to do if the back bevel were applied before the camber.) And lastly, if you do apply this back bevel, what do you do when sharpening with the blade in a jig and you want to remove the burr? You can't replicate the geometry used to establish the back bevel because the jig is in the way.
David C
In Memorium
BB,
Don't know much about history (song quote)
Textured, burnt and coloured surfaces seem to be very much the province of the American studio art movement i.e. starting in the sixties and seventies??
Mousey Thompson used adze for tops?
Adrian,
Fraid rather rushed today, cambering a blade from scratch in my system takes no more that 5 - 10 minutes, on an 800g stone.
Describing and showing the process takes nearly 1 1 /2 hours on my DVD.
best wishes,
David Charlesworth
Don't know much about history (song quote)
Textured, burnt and coloured surfaces seem to be very much the province of the American studio art movement i.e. starting in the sixties and seventies??
Mousey Thompson used adze for tops?
Adrian,
Fraid rather rushed today, cambering a blade from scratch in my system takes no more that 5 - 10 minutes, on an 800g stone.
Describing and showing the process takes nearly 1 1 /2 hours on my DVD.
best wishes,
David Charlesworth
bugbear
Established Member
David C":31mhwmeb said:
The table (IIRC) was in the main Bayleaf building
http://www.wealddown.co.uk/quick-tour-o ... eton-4.htm
and was meant/claimed to be authentic to period, hence my disappointment.
BugBear
David C":5y5kc4za said:
Thanks for taking the time to post here.
I was following the method from your book---I haven't seen the DVD (but I notice that it covers in its 75 minutes a lot more than just cambering a blade). I can think of two things that would have made me slow. One is that I spent at least half the time trying to decide if I was done yet. The second is that my secondary bevel is about 3mm wide. I'll wager yours is much smaller than that so you have a lot less metal to remove. (I don't have a powered grinder to use to grind back the primary bevel. Doing that would have taken even longer. After a recent experience with a nick in a 42 mm chisel I've concluded that I need some sort of power grinder, but I don't yet have anything.)
Another possible factor is that I've been flattening the 320 grit stone on a sheet of glass with lapping grit and it appears that this process leaves it slightly convex. This probably doesn't help, though I don't know if it hurts much.
I had a chance to test my cambered blade last night. When I was getting a 1-2 thou shaving the cut was under 1/2 inch wide. When I increased to a 3-4 thou shaving the cut was about 1 inch wide. (Note, however, that my shaving measurements seem rather uncertain. I'm planing oak that is making very crinkly shavings that are hard to measure.)
I forged ahead and tried to flatten a board with this plane and I realized something else that might be of interest to others trying to follow the instructions in the DVD. I was trying to plane using a stop as directed. And the wood defiantly remained convex. Why? I realized after a while that an important factor is that the bottom face of my wood is concave by .5 mm or so. And it was easily able to flex under pressure. When I ignored the advice in the DVD to not squeeze the timber and instead secured it lightly at both ends and put shims under it, then all of a sudden the plane started cutting at the high spot. I'm not sure how I can support the underside to prevent flexing without squeezing the wood. (The wood is 3/4" thick.)
I forged ahead and tried to flatten a board with this plane and I realized something else that might be of interest to others trying to follow the instructions in the DVD. I was trying to plane using a stop as directed. And the wood defiantly remained convex. Why? I realized after a while that an important factor is that the bottom face of my wood is concave by .5 mm or so. And it was easily able to flex under pressure. When I ignored the advice in the DVD to not squeeze the timber and instead secured it lightly at both ends and put shims under it, then all of a sudden the plane started cutting at the high spot. I'm not sure how I can support the underside to prevent flexing without squeezing the wood. (The wood is 3/4" thick.)
David C
In Memorium
You can try paper or card strips to support the middle or any place that needs support.
Alternatively do some work on the opposite side to improve registration on the bench.
Sometimes it is best to work each side alternately untill one surface sits on the bench. No long plank can be planed flat until it is sitting on the bench. The problem becomes much more acute as the work gets thinner and longer.
This is why cabinetmakers must have flat benches......
Crinkly shaving suggest a chipbreaker front edge problem?
David
Alternatively do some work on the opposite side to improve registration on the bench.
Sometimes it is best to work each side alternately untill one surface sits on the bench. No long plank can be planed flat until it is sitting on the bench. The problem becomes much more acute as the work gets thinner and longer.
This is why cabinetmakers must have flat benches......
Crinkly shaving suggest a chipbreaker front edge problem?
David
bugbear
Established Member
David C":2zejhevn said:
Shavings always crinkle, due to the nature of the cutting process (IIRC Leonard Lee's book goes into detail).
Try measuring the LENGTH of a shaving from a 3 foot plank...
BugBear
David C
In Memorium
Thanks BB,
Well in that case there are; crinkle, degrees of crinkle and extrememe concertina.
There are certainly differences, possibly due to wood species as well.
Concertina is not good.
David
Well in that case there are; crinkle, degrees of crinkle and extrememe concertina.
There are certainly differences, possibly due to wood species as well.
Concertina is not good.
David
dunbarhamlin
Established Member
I'm sorry David, at this time of year one only derides Crass Crinkle at the risk of suffering the forlorn cries of children.
:lol:
Steve
:lol:
Steve
The shavings I'm getting from this oak are kind of lacy, with maybe 30% of the shaving missing. The parts that are present curl up and because they are narrow, it's hard to get them into the calipers and be completely sure that I have the shaving flat and I'm not gettings a second layer of shaving. The crinkling is local. The overall character of the shavings at a larger scale is that they curl up into rolls. They're not folding back and forth like a concertina.
David C
In Memorium
Steve,
Nice one...
Adrian,
Your shavings sound fine to me. Slightly less camber should result in wider shavings. How is the surface finish on the boards?
David
Nice one...
Adrian,
Your shavings sound fine to me. Slightly less camber should result in wider shavings. How is the surface finish on the boards?
David
I haven't inspected surface finish very closely, but it looks and feels smooth. I don't see or feel the scallops that are presumably there.
The only remaining difficulty I have is that after a series of stop shavings, the board is slightly concave (<0.002") as desired. But if I take a set of through shavings to clean up the ends, the board becomes slightly convex (with the hump about 4 inches in from the side where the shaving starts).
The only remaining difficulty I have is that after a series of stop shavings, the board is slightly concave (<0.002") as desired. But if I take a set of through shavings to clean up the ends, the board becomes slightly convex (with the hump about 4 inches in from the side where the shaving starts).
