Tuesday, 13 July 2010

up & down - bevels that it

A few weeks ago, I was doing some site work - some inlay in a Mahogany staircase. I had to inlay twelve flame Birch panels into the stair treads. They were left a little over-sized in thickness and then planed flush with the treads once they were installed. For anyone who has ever worked with flame birch - you are likely cringing right now because you know what kind of nightmare flame birch can be to work with. Lots and lots of honing.

There were three planes in my line-up that were suited to this work; the XSNo.4 smoother, the SNo.4 smoother and my LN block plane. They are all narrow and nimble planes and were able to follow and maintain the gentle curvature of the solid treads.

The reason for this post is not to start a war - but to show the different wear on working tools. I used the SNo.4 and the block plane to do the lions share of the work, and then finished up with the XSNo.4 set to take a very fine shaving. The XS is the smallest and most nimble in the bunch. All three planes performed their task wonderfully, but this experience reminded me of why I developed the XSNo.4 in the first place. I wanted a one handed (and very small) smoother that was in a bevel down (BD), high bed angle configuration. I was frustrated with the location of the wear on my bevel up (BU) block plane. Before I get too far into it - here are a few photos of the blade of the SNo.4 smoother (BD) and the block plane (BU).

Oh, - I should also explain a bit of how I sharpen. Both blades are hollow ground to about a 34 degree angle, the backs are flat, and there are no micro bevels or “ruler trick” back bevels.


(click on any of the images for a larger view)


The BD smoother blade on the left and the BU block plane blade on the right. Notice the amount of wear to the back side of the cutting edge on the BU blade.




Here is the bevel side of the BU block plane blade. Notice there is significantly less “wear” to the cutting edge.




The “back” of the iron of the BD blade.



And the bevel side of the BD blade.

So here is my observation based on using these two planes - they both required frequent re- honing, but the blade of the BU block plane required a lot more work to get it to a freshly honed state. I had to re-grind before each honing in order to get rid of the wear to the “back” (the flat side) of the iron which saw more wear than the bevel side. The bevel down blade seemed to have a similar amount of wear to each side and was less effort to re-hone because of it.

If anyone has any insight into what I might be able to do to reduce the amount of wear to the “back” of the BU iron - I would love to hear it. Or if people have had similar experiences with any BU vs BD planes I would love to hear from you as well.

31 Comments:

Blogger matt@thuja said...

I got to see those stairs last weekend and they looked great. I was wondering how much honing you had to do because that was a lot of planing (and in an awkward, non-benchtop type position to boot). The only thing I can think of with regard to BU vs BD is that the wear on any blade is due to hard particles that aren't being cleanly cut...the lower blade angle of the "back" of the blade (the side against the bed of the plane) for a BU plane would mean the hard particles would drag through more metal than in the BD plane. This would make the back of the blade in a BU plane have a longer wear region than a BD. I think that makes sense from a geometry point of view at least, but I think I need a diagram ;)

Matt

19 July 2010 15:51  
Anonymous Anonymous said...

Could it be that you are not comparing apples to apples?

Your LN is bedded at 12 degrees (low angle)? But the smoother is what 50-55? less the 34 degree bevel means there is 16 - 20 degrees relief behind the bevel.

Like Matt said "a longer wear region than a BD"

Eric in Nova Scotia

19 July 2010 19:15  
Anonymous Anonymous said...

Fiber spring-back. That is the issue for any cutting tool whether cutting wood, metal or tomatoes.

There is simply more contact against the relief side of a cutting tool as the material is being cut on a low-angle cutting tool.

There is nothing that can be done about it in the sense of stopping it.

This applies to bevel up or down planes equally. For instance, one can own (I do) a bevel down strike block plane that has a relatively low bedding angle (I think mine is 38 deg). The bevel side--which is down in this instance--will wear more quickly than a higher-angle bedded plane.

The only mitigation is to be aware of this fiber spring-back and hone more frequently on a BU plane or a BD plane with a low bedding angle.

Take care, Mike

21 July 2010 09:16  
Anonymous Pitonyak said...

Although I cannot disagree with previous comments, I keep staring at the pictures that I drew and thinking that something seems off. You do not mention that actual values used, but, one poster specifically uses values such as 12 degrees bedding and mentions a 34 degree bevel. I assumed, therefore, a 34 degree bevel on the blade and then a bedding angle of 54 degrees for the high angle BD and 12 degrees for the low angle BU.

Now, push the plane into the shaving. There are forces pushing into the blade. With a lower effective angle, lower, so I expect less force directly into the blade.

21 July 2010 12:00  
Anonymous Derek Cohen said...

Hi Konrad

While spring back is expected to contribute to a larger wear bevel of a BU plane (vs a BD plane), I have never see wear like your blade. I am assuming that the LN is A2 steel? How much use? Frankly this is not even a case of comparing apples with oranges (the 12 degree BU blade and a york pitch BD blade) to achieve meaningful results - that amount of wear is bizarre.

I am in the process of researching the wear on different types of steels (O1, A2, CPM 3V, and a few others) in BU and BD planes, and this includes evaluating BU blade configurations at different bed angles (in this case, 12- and 25 bed degrees) to judge the degree of wear on the back of the blade. One of the tests recently has been using different cutting angles on a 12 degree bed on a shooting board. At no time, following repeated planings (such as 100 full shavings on a West Australian hardwood in each session), did I approach wear on the back of the blade that resembled your picture (which is why I wonder what else is going on there). In fact, using magnification as high as 200X I cannot find any signs of a wear bevel at all after 100 shavings, and this using A2 steel (the same as the LN block plane).

Mmmm ... interesting.

Regards from Perth

Derek

22 July 2010 01:08  
Blogger Konrad said...

Hi Matt,

Ooh - I have to go and take some photos of the finished staircase!

Thanks for your comments - they seem to be shared by many.

Cheers,
Konrad

22 July 2010 07:54  
Blogger Konrad said...

Thanks Eric. I am not comparing apples to apples in the sense that the planes are totally different. But... they are both touted as excelling at this type of work - and one clearly requires more work to maintain than the other. I totally agree that the clearance angle is the issue here - but it does beg the question - why use a BU plane for heavy stock removal if it results in greater effort to maintain the cutting edge?

Cheers,
Konrad

22 July 2010 07:57  
Blogger Konrad said...

Thanks Mike,

Fiber spring-back. Thanks for mentioning this. I had not really considered it (maybe wrongly too). but you seem to have concluded the same thing I have - if a BU and BD plane are given the same amount of work - the BU blade will require more work to restore the cutting edge. Is that an accurate paraphrasing?

Thanks for your comments,
Konrad

22 July 2010 08:01  
Blogger Konrad said...

Pitonyak,

Sorry for leaving out some details. The block plane does have a 12 degree bed angle and the BD smoother has a 52.5 degree bed angle. The effective cutting angle of the block plane is 46 degrees.

Cheers,
Konrad

22 July 2010 08:11  
Blogger Konrad said...

Hi Derek - thanks for jumping in.

Yes - the blade in the block plane is the standard A2 blade. I have had it for about 6 years now, and have had to re-grind many, many times - so I should be well past the sometimes weaker factory edge. The blade in the BD plane was made by Ron Hock - it is high carbon steel (01).

If I understand your comments correctly, you seem to be suggesting that this is an unfair comparison because you think the A2 blade is faulty. Is that correct?

Cheers,
Konrad

22 July 2010 08:19  
Anonymous Anonymous said...

Me thinks Derek has magic blades...[g].

This isn't new science. It is an established fact: Less clearance angles means edge wear in a less proportionate way as regards the amount of wear on each side of the cutting edge.

It (this uneven wear pattern) is measurable and demonstrable. It has been published on many, many times inside and outside the woodworking industry.

To me, the weird thing isn't that Mr. K's blades amply illustrate this fact. The weird thing to me is that Derek's seemingly do not.

I believe that while such disparate bedding angles Mr. K is using are not directly correlative, neither are 12/25 bedding angles. Both pairs of blades do (should) illustrate there is greater wear on the back side of the blades. It is just a 12/25 deg. comparison will have less a difference.

Further, Mr. K's blog entry demonstrates the issue involved with honing/sharpening requirements for folks who either have or are thinking about low angle planes versus higher angle planes.

For myself, knowing that my BU, low angle planes require more frequent honing is a "who cares" issue. LA BU planes are worthy planes for many tasks (as well as the BD LA strike block plane I mentioned). It is just I need to pop out a blade a little more often to renew the edge.

Knowing I need to hone more frequently means that, well, I do so. If renewed via honing (I use fine compound on a Makore slab of wood, just like my "bevel up paring chisels [g]), frequently enough (not that often) means they remain sharp.

I have not reground my BU LA plane blades (nor the BD LA blade, nor my paring chisels) in years.

Take care, Mike

22 July 2010 09:03  
Anonymous Derek Cohen said...

"If I understand your comments correctly, you seem to be suggesting that this is an unfair comparison because you think the A2 blade is faulty. Is that correct? "

Hi Konrad, and no - I am not drawing any conclusions. All I was saying is that the degree of wear you demonstrated puzzles me. While I do anticipate some, yours was far more that I would expect.

Mike wrote, "For myself, knowing that my BU, low angle planes require more frequent honing is a "who cares" issue. LA BU planes are worthy planes for many tasks (as well as the BD LA strike block plane I mentioned). It is just I need to pop out a blade a little more often to renew the edge."

I totally agree with this sentiment. I am curious about the speed and degree to which a wear bevel developes on a BU blade, however this is really academic since the performance that may be achieved from a high angle BU Smoother can be second-to-none (apologies Konrad :)).

Back to blade wear - I have recently begun examining the edges of blades under high magnification. Now this may be a reflection of my naivity at this stage, but one conclusion I could draw is that - on a shooting board - the edges may disintegrate (become more serrated) long before they degrade as a result of wear on the back of a blade. I posted some images on Sawnill Creek not too long ago (http://sawmillcreek.org/showthread.php?p=1458742#post1458742). I am going to compare this now with wear from the relatively more gentle smoothing action.

Regards from Perth

Derek

22 July 2010 10:17  
Anonymous Anonymous said...

When measuring wear bevels, I think it will take more sophisticated equipment than is readily at hand.

Not only should length be measured (from the edge back up the length of the cutting tool), but also width (across the thickness of the cutting tool). Only then would it be possible to truly graph meaningful results.

A wear bevel isn't a "new" bevel-shaped thing. It has a radius. Simply measuring back from the edge will not give a true picture of the degree of wear.

Best wishes. Mike

22 July 2010 13:35  
Blogger Konrad said...

Hi Mike,

Thanks again for all your comments. You hit one of the nails on the head for me - the issue of the trade off between one plane and another as it relates to time and effort to maintain an effective cutting edge. For you it is not that big a deal - I fully accept that. For me it is a little different; if I have two tools to choose from and one take more effort to maintain - I will use the one that allows me to be the most efficient. It is as simple as that for me.

“bevel up paring chisels” - now that was funny!

Cheers,
Konrad

22 July 2010 20:34  
Anonymous Larry Williams said...

As Mike mentioned, inadequate clearance can be a problem with bevel down planes. The strike block is a prime but unusual example.

While few bevel down planes are bedded around 40º like the strike block. One has to be careful to maintain an acute bevel of no less than 25º with a 40º bed and to keep the iron very sharp while taking only the finest of cuts. If you don't, you'll run into clearance angle problems. It's the reason the structurally flawed wooden miter plane replaced in the early 19th Century. Not only was the 20º bedded wooden miter plane prone to structural failure it required a mouth closing stop which contributed to its cost being three times greater than the strike block.

I've also had clearance angle problems with my middle pitch smooth plane. This has happened when trying to rush good sharpening, avoiding maintaining a small secondary bevel and lifting while honing to speed sharpening. When the bevel angle gets close to 35º the plane lacks adequate clearance which causes problems. So a 20º clearance angle isn't enough for a 55º angle of attack.

The difference between bevel-down planes and 12º bevel-up planes is that the clearance angle issues are built into the 12º planes. These built in problems can only be avoided by careful stock selection, maintaining an acute bevel angle and taking only the lightest of cuts with a very sharp iron.

22 July 2010 21:01  
Anonymous Anonymous said...

So is this the fault of the bevel up blade, or the 12 degree bed angle?

I'm thinking a little of both.

I like the BU idea, but I simply have no need for such a low bedding angle.

22 July 2010 21:01  
Anonymous Derek Cohen said...

"if I have two tools to choose from and one take more effort to maintain - I will use the one that allows me to be the most efficient. It is as simple as that for me."

Hi Konrad

I agree ... to a point.

First of all I must clarify that I consider the advantage of a BU plane lies at the cutting angle extremes - either low or high, but not the middle range. The middle range (say 40- 50 degrees) is one I view the domain of the BD plane. I say this with some reserve since I have several BD smoothers with beds at 60 degrees.

The issues are this:

There is an advantage in a low cutting angle on the shooting board.

There is an advantage in a high cutting angle with interlocked grain (not necessarily hard wood). Generally we are referring to the use of smoothers in this context, but not always.

BU planes are easier to set up at these extremes. Of course one may set up a BD plane with a high cutting angle, but all variables otherwise held equal, the BU plane is easier to push than the BD plane.

The downside for me of a BU plane - with a 12 degree bed - is that it must use a microbevel to achieve the chosen high cutting angle. This is best done with a honing guide. Personally I prefer honing freehand, and the discipline of a honing guide is something that I reluctantly accept ... simply because the performance of BU smoother with a high cutting angle is so good.

Now the limiting factor here is the 12 degree bed. So I went ahead and built an infill BU with a 25 degree bed (http://www.inthewoodshop.com/ShopMadeTools/A_Galoots_infill_smoother.html). I use a 35 degree hollow ground primary bevel, and the result creates a 60 degree cutting angle. The performance is superior.

On the shooting board a favourite is a LA Jack. This benefits from a low cutting angle. The 25 degree bevel is straightforward to freehand, so no issues there.

On all other planes that benefit from a common or york pitch I prefer a BD configuration for ease of sharpening. Issues of edge longevity rarely come into the equation.

Regards from Perth

Derek

23 July 2010 05:38  
Blogger Konrad said...

Hi Derek,

Thanks for clarifying you are not drawing any conclusions based on photos.

The wear I experienced is pretty consistent with the wear I usually see on edge tools when I am using them for a more coarse application - like fairly heavy stock removal on a challenging timber like flame birch. I was not using either tool as a finishing tool, but I was also not working so coarse as to tolerate tearout. One of the problems with discussions like this is the limitations of our language. For me to say “challenging timbers like flame birch” means one thing to me and maybe a few others... but some may not find it challenging to work with at all. Your comment about “performance from high (cutting angle) BU planes is second to none“... I do not really know what that means because I have no context for what your expectations are. That statement may be 100% accurate for you - but I have nothing to compare it to. Your parameters of high performance may be different than mine in that they may include different criteria. For me, a planes overall performance includes how easy it is to maintain the cutting edge, how easy is it to adjust in use, how comfortable it is, how the plane behaves when the iron is dull, how does it behave when I am actually working (as opposed to testing a plane), etc, etc. These are not quantifiable performance issues, but they are highly valuable to me.

A very good friend of mine called the other day to talk about this issue and pointed out that I should also not discount my own skills with my own planes and with planes in general.

He also reminded me that everything is a trade off - there is no magic bullet out there. The point of my post was to draw attention to an aspect of low bed angle planes - the wear area is very pronounced and requires more work (for me) to remove it. I wanted to point it out in case there were others out there who were experiencing inconsistent results with similar plane configurations. As Mike pointed out - for him it is not a big deal. That is a perfect answer - he likely has different patterns for maintaining a cutting edge - and neither of us is right or wrong - just different.

I will comment on your second comment here as well (man this is a lot of typing!)

Interesting comment about your need for a micro bevel on a low bed angle, BU blade. I am also a freehand honer and the idea of micro bevels is frankly more work and I fear that I create a moving target with where exactly the cutting edge is. I guess I am a bit simplistic in my approach - but If the back of the iron is flat, and if I can maintain the bevel - I only have 2 faces to worry about. A micro bevel creates a third face that is generally so small, it cannot be seen and may make it harder to control.

You made the comment that the the performance of a BU smoother with a high cutting angle is “so good”... but wouldn't the “performance” be the same with a BD plane with a comparable fixed bed angle? Attack is attack angle isn't it?

Can you explain “superior performance” from your 25 degree bed angle, 35 degree bevel, BU infill?

Thanks for all your comments,
Konrad

24 July 2010 17:22  
Blogger Konrad said...

Hi Derek,

Thanks for clarifying you are not drawing any conclusions based on photos.

The wear I experienced is pretty consistent with the wear I usually see on edge tools when I am using them for a more coarse application - like fairly heavy stock removal on a challenging timber like flame birch. I was not using either tool as a finishing tool, but I was also not working so coarse as to tolerate tearout. One of the problems with discussions like this is the limitations of our language. For me to say “challenging timbers like flame birch” means one thing to me and maybe a few others... but some may not find it challenging to work with at all. Your comment about “performance from high (cutting angle) BU planes is second to none“... I do not really know what that means because I have no context for what your expectations are. That statement may be 100% accurate for you - but I have nothing to compare it to. Your parameters of high performance may be different than mine in that they may include different criteria. For me, a planes overall performance includes how easy it is to maintain the cutting edge, how easy is it to adjust in use, how comfortable it is, how the plane behaves when the iron is dull, how does it behave when I am actually working (as opposed to testing a plane), etc, etc. These are not quantifiable performance issues, but they are highly valuable to me.

A very good friend of mine called the other day to talk about this issue and pointed out that I should also not discount my own skills with my own planes and with planes in general.

He also reminded me that everything is a trade off - there is no magic bullet out there. The point of my post was to draw attention to an aspect of low bed angle planes - the wear area is very pronounced and requires more work (for me) to remove it. I wanted to point it out in case there were others out there who were experiencing inconsistent results with similar plane configurations. As Mike pointed out - for him it is not a big deal. That is a perfect answer - he likely has different patterns for maintaining a cutting edge - and neither of us is right or wrong - just different.

I will comment on your second comment here as well (man this is a lot of typing!)

Interesting comment about your need for a micro bevel on a low bed angle, BU blade. I am also a freehand honer and the idea of micro bevels is frankly more work and I fear that I create a moving target with where exactly the cutting edge is. I guess I am a bit simplistic in my approach - but If the back of the iron is flat, and if I can maintain the bevel - I only have 2 faces to worry about. A micro bevel creates a third face that is generally so small, it cannot be seen and may make it harder to control.

You made the comment that the the performance of a BU smoother with a high cutting angle is “so good”... but wouldn't the “performance” be the same with a BD plane with a comparable fixed bed angle? Attack is attack angle isn't it?

Can you explain “superior performance” from your 25 degree bed angle, 35 degree bevel, BU infill?

Thanks for all your comments,
Konrad

24 July 2010 17:23  
Blogger Konrad said...

Hi Derek,

Thanks for clarifying you are not drawing any conclusions based on photos.

The wear I experienced is pretty consistent with the wear I usually see on edge tools when I am using them for a more coarse application - like fairly heavy stock removal on a challenging timber like flame birch. I was not using either tool as a finishing tool, but I was also not working so coarse as to tolerate tearout. One of the problems with discussions like this is the limitations of our language. For me to say “challenging timbers like flame birch” means one thing to me and maybe a few others... but some may not find it challenging to work with at all. Your comment about “performance from high (cutting angle) BU planes is second to none“... I do not really know what that means because I have no context for what your expectations are. That statement may be 100% accurate for you - but I have nothing to compare it to. Your parameters of high performance may be different than mine in that they may include different criteria. For me, a planes overall performance includes how easy it is to maintain the cutting edge, how easy is it to adjust in use, how comfortable it is, how the plane behaves when the iron is dull, how does it behave when I am actually working (as opposed to testing a plane), etc, etc. These are not quantifiable performance issues, but they are highly valuable to me.

A very good friend of mine called the other day to talk about this issue and pointed out that I should also not discount my own skills with my own planes and with planes in general.

He also reminded me that everything is a trade off - there is no magic bullet out there. The point of my post was to draw attention to an aspect of low bed angle planes - the wear area is very pronounced and requires more work (for me) to remove it. I wanted to point it out in case there were others out there who were experiencing inconsistent results with similar plane configurations. As Mike pointed out - for him it is not a big deal. That is a perfect answer - he likely has different patterns for maintaining a cutting edge - and neither of us is right or wrong - just different.

I will comment on your second comment here as well (man this is a lot of typing!)

Interesting comment about your need for a micro bevel on a low bed angle, BU blade. I am also a freehand honer and the idea of micro bevels is frankly more work and I fear that I create a moving target with where exactly the cutting edge is. I guess I am a bit simplistic in my approach - but If the back of the iron is flat, and if I can maintain the bevel - I only have 2 faces to worry about. A micro bevel creates a third face that is generally so small, it cannot be seen and may make it harder to control.

You made the comment that the the performance of a BU smoother with a high cutting angle is “so good”... but wouldn't the “performance” be the same with a BD plane with a comparable fixed bed angle? Attack is attack angle isn't it?

Can you explain “superior performance” from your 25 degree bed angle, 35 degree bevel, BU infill?

Thanks for all your comments,
Konrad

24 July 2010 17:23  
Blogger Konrad said...

Hi Derek,

Thanks for clarifying you are not drawing any conclusions based on photos.

The wear I experienced is pretty consistent with the wear I usually see on edge tools when I am using them for a more coarse application - like fairly heavy stock removal on a challenging timber like flame birch. I was not using either tool as a finishing tool, but I was also not working so coarse as to tolerate tearout. One of the problems with discussions like this is the limitations of our language. For me to say “challenging timbers like flame birch” means one thing to me and maybe a few others... but some may not find it challenging to work with at all. Your comment about “performance from high (cutting angle) BU planes is second to none“... I do not really know what that means because I have no context for what your expectations are. That statement may be 100% accurate for you - but I have nothing to compare it to. Your parameters of high performance may be different than mine in that they may include different criteria. For me, a planes overall performance includes how easy it is to maintain the cutting edge, how easy is it to adjust in use, how comfortable it is, how the plane behaves when the iron is dull, how does it behave when I am actually working (as opposed to testing a plane), etc, etc. These are not quantifiable performance issues, but they are highly valuable to me.

A very good friend of mine called the other day to talk about this issue and pointed out that I should also not discount my own skills with my own planes and with planes in general.

He also reminded me that everything is a trade off - there is no magic bullet out there. The point of my post was to draw attention to an aspect of low bed angle planes - the wear area is very pronounced and requires more work (for me) to remove it. I wanted to point it out in case there were others out there who were experiencing inconsistent results with similar plane configurations. As Mike pointed out - for him it is not a big deal. That is a perfect answer - he likely has different patterns for maintaining a cutting edge - and neither of us is right or wrong - just different.

I will get to your other post in a second...

Cheers,
Konrad

24 July 2010 17:24  
Blogger Konrad said...

Hi (again) dereck,

Interesting comment about your need for a micro bevel on a low bed angle, BU blade. I am also a freehand honer and the idea of micro bevels is frankly more work and I fear that I create a moving target with where exactly the cutting edge is. I guess I am a bit simplistic in my approach - but If the back of the iron is flat, and if I can maintain the bevel - I only have 2 faces to worry about. A micro bevel creates a third face that is generally so small, it cannot be seen and may make it harder to control.

You made the comment that the the performance of a BU smoother with a high cutting angle is “so good”... but wouldn't the “performance” be the same with a BD plane with a comparable fixed bed angle? Attack is attack angle isn't it?

Can you explain “superior performance” from your 25 degree bed angle, 35 degree bevel, BU infill?

Thanks for all your comments,
Konrad

24 July 2010 17:25  
Blogger Konrad said...

Hi Larry,

Thanks for jumping into the soup!

And thanks for your insight into the strike block plane. I had ready Joel’s post about them a while back and noticed that Bill Carter has made a few.

Hmmm... interesting comment on clearance angles for high bed angle BD planes - I will keep an eye out for that issue. I suppose a burnishing effect would be worst thing to encounter - and it would only show up when you went to apply finish. At that point it may be too late to correct for it.

Cheers,
Konrad

24 July 2010 17:42  
Blogger Konrad said...

Anonymous - your short question may sum it all up. This may very well be the fault of a 12 degree bed angle as opposed to a BU vs BD blade. As Larry observed - the clearance issue is built into 12 degrees.

Thanks for your input.
Konrad

24 July 2010 17:46  
Anonymous Derek Cohen said...

"You made the comment that the the performance of a BU smoother with a high cutting angle is “so good”... but wouldn't the “performance” be the same with a BD plane with a comparable fixed bed angle? Attack is attack angle isn't it?

Can you explain “superior performance” from your 25 degree bed angle, 35 degree bevel, BU infill?"

Hi Konrad

I think that we are on the same page when you write, " everything is a trade off - there is no magic bullet out there". There are pros and cons about every plane for everyone, no doubt including your own - :) - simply because we all have different priorities.

Here is a reference of sorts for you. I work almost exclusively with Australian timbers. Most are an Eucalypt. There are generally very hard and mostly abrasive (high levels of silica) and the grain has a high degree of interlock. Examples being old Jarrah and Western Australian She-oak. A high cutting angle (around 60 degrees) is preferred to limit tearout. The abrasiveness of the woods have also increased the local interest in steels such as HSS and D2. A2 is taken for granted.

I have several smoothers with high cutting angles. These range from LN #4 1/2 (york pitch frog), Brese (half pitch) to HNT Gordon (half-pitch bed) to Veritas BU (BUS and LAS) and a few I have built in both wood and metal (such as the 25 degree bed infill I mentioned earlier). Here is the thing ...

... with cutting angle and blade width held constant, the low centre of gravity and low centre of effort of a BU plane makes it significantly easier to push for a fine smoothing cut than the BD plane. In my BD planes I need to restrict them to a 2" width to manage, otherwise they become fatiguing.

OK the "superior performance" thing about the 25 degree bed BU smoother ... (Oh god, this is a long post again!)

One of my priorities with a plane is the ease of use. I like it to be comfortable to hold, easy to push, that the blade is easy to remove and replace ... and that the edge is easy to maintain. The one complaint I have about high angled BU planes is that they really do require a microbevel *if you want to camber the blade* (= less steel to remove that from the face of a high angle primary grind). I prefer to freehand when honing, and I tend to refresh the edge of the blade before it needs honing. Freehanding a microbevel at a specific angle is not doable. So they require a honing guide.

The upside of a BU smoother is that it is easy to achieve a high cutting angle, and this is a big factor in preventing tearout (yes I know there are other factors as well). Dropping the cutting angle even 5 degrees with some grain can lead to considerable tearout.

Raising the bed from 12- to 25 degrees not only reduces the potential for wear on the back of the blade (the point that Larry raises so frequently), but brings the 35 degree primary bevel into a range where it may be cambered easily enough freehand. It is probably also a more durable edge than on the average BD plane (at 25 - 30 degrees).

Stopping now to head to the workshop!

Regards from Perth

Derek

24 July 2010 21:30  
Blogger raney said...

Just a quick point regarding Derek's experience -

While australian timbers are almost certainly more abrasive than the 'norm' on this continent, they also exhibit MUCH less springback, which - as Mike has pointed out - is the primary mechanism for the wear bevels. So it makes some sense that a 12 degree clearance would be less of an 'issue' for Derek.

My experience completely coincides with what Mike and Konrad have said, and what Larry Williams has been saying for years: in general, low angle designs are more difficult to maintain than planes with higher clearance angle - and in my opinion, 12 degrees is lower than I would like in most situations.

Bevel up designs have their place, and it's all about tradeoffs indeed, but there seems to be something of a notion that they are a 'magic bullet' among many people. I don't agree, and use them pretty infrequently as they really call for a sharpening regimen that is very different than mine; I'm a freehand sharpener as well, and microbevels, secondary bevels, and back bevels all cause my colon to stiffen.

28 July 2010 10:41  
Anonymous Ian Neuhaus said...

Hi Konrad
All other things being equal, I think it comes down to the basic difference in geometry between BD and BU planes.

With a BD plane, it's the flat back of the blade that does the cutting and the bevel side that experiences wear from fibre springback. When you re-hone the bevel to freshen the cutting edge you automaticly remove any wear caused by fibre springback.

With a BU plane, it's the bevel side that does the cutting and the flat back which experiences any wear from fibre springback. When you rehone the bevel to freshen the edge, you are not really touching much of the area on the back of the blade affected by fibre spring back.

I hope this makes sense
Ian

31 July 2010 08:45  
Anonymous David Charlesworth said...

Hi Konrad,

It may have escaped some of your posters attention, that the ruler trick removes metal from precisely the area of the back of the blade where you have shown the wear for the 12 degree L-N block plane.

I do hope your finger has healed well,
best wishes,
David Charlesworth

9 August 2010 14:39  
Anonymous Anonymous said...

(late to the party)

All other equal (clearance angle, etc) it takes more work to remove wear area from BU plane. If it is, let's say, 0.3 mm at 5 degree, you'll have to grind all 0.3 mm from a BU blade, but only 0.03mm from BD blade (5 deg being about 1/11 of incline). You get the idea.

3 September 2010 19:00  
Blogger Drroov said...

Also a bit late;

I have just recently encountered the issue. I'm using only Veritas BU planes, and indeed the wear on the backside of the blade is pronounced, even on European woods. The solution I am trying right now - I know it sounds risky - is to use a longer than usual back bevel, about a centimeter long. Hopefully, the blade would still be supported securely on the bed (although not on its very end), and the cutting edge should benefit from increased resistance to nicking. Any comments?

Regards,

Tomasz Segiet

21 September 2010 16:06  
Blogger Konrad said...

Hi Tomasz,

Better late than never! Thanks for jumping in.

I am not 100% sure I am following your current solution, but my fear would be that the longer back bevel will get you closer to a zero clearance angle. I look at it this way - if I had to remove that long back bevel, I would be at the grinder for hours. I guess in theory, you will have an edge that is less prone to nicking... but the "cost" may be higher than I would be willing to pay. Good luck with it and please let me know how it goes. For all I know - you may be onto something with this.

Cheers,
Konrad

21 September 2010 19:34  

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