Sharpening / wear tests and pictures

[Shady]

Ok folks, I've been thinking about all this. I spent today cutting back 9 different irons for comparitive tests:Bevel down - a 'standard' 1990's stanley (UK) iron, because we all cheerfully rubbish them, but I've not seen them actually compared in this sort of test... A Clifton 'hand forged', and a 'Samurai' laminated japanese iron, and a Hock. Bevel up - a L-N A2 cryo, a L-V non cryo A2, and a Record 'crucible forged tungsten steel' 1950's blade...
Finally, for interest, a 100 year old 'generic' shoulder plane blade, and a similar vintage Norris blade.

They are all now cut to 240 grit wet/dry. Next step will be a 25 degree hollow grind on the wet wheel, and a 30 degree bevel on the whetstones.

Thoughts on testing:

I want them all to have the same 'included angle' - 30 degrees. Rationale is that this means we are comparing 'like with like' in terms of strength of the steel.

I've looked into all the available stuff I can find. It strikes me there are 2 'degradation' aspects: one is 'wear' pure and simple - equivalent to shoving the blade through sand (or any other uniform resistance) until it is blunted beyond use...

The other is the 'dynamics' of actually planing wood - a 'non- isotropic' material. This means that, even if I try to find a uniform piece of wood, we cannot be sure what differences are occuring as each stroke exposes fresh wood. I have a personal suspicion that this is more important than generally realised: I think the dynamic load, leading to flexing/bending, may well generate unpredictably very high loads at the tip, leading to failure in a non 'comparable' manner.

I therefore intend to 'wear' the blades on MDF, as this should make any dynamic effects common (or at least, a lot more common) for all blades...

I'm also going to try and get microscope pictures of the surface of planed test pieces of hard and softwood, to show what it looks like at relative stages of blade wear.

I'd welcome any comments on any of this... Seriously interested now...

 

[Vormulac]

For goodness sake Shady, use a carving knife on your turkey like everyone else!! :wink: :lol:

Seriously, I'll be interested to see how this experiment comes out!

V.

 

[Anonymous]

Shady

Sounds quite sensible to me.

You could take the view that when planing wood, the edge does take rather a long time to wear away and so any variations in wood texture/strength will not have a significant impact on the tests as it will be lost in the noise.

However, MDF is very abrasive and will wear an edge very quickly and should present a uniform resistance to each shaving. I would take great care over the thickness of shavings taken form each piece to ensure similar loads are placed on the edges.

For a statistically significant result, you should carry out the tests several times with each blade with as many controlled conditions as possible - thickness of shaving, uniformity of material, speed and length of stroke etc.
When you have, say, ten sets of test results, then average them to remove any noise from the data and finally compare

If you really want to ensure that you analyse a set of tests properly to give 95% confidence in the results (this is the level of error we usually accept), then pm me with your email address and I will send you a boring email outlining the maths.

 

[Shady]

Tony - happy with that - our applied maths boys are one floor below me in work... :wink: I agree that it'll wear them very quickly, and I actually see that as an advantage - it'l be quicker to compare results.

FYI, I also intend to compare going up to 10,000 grit waterstone, 2000 grit wet/dry, stropping, and using autosol polish on glass. All will be done in a jig to eliminate any 'manual bias'...

 

[Chris Knight]

Shady,

MDF is very anisotropic. Notably, it is made up of layers of differing density. Please don't use this!

I heartily recommend some soft maple. It is quite hard despite the name and produces a lovely finish with a sharp iron. Alternatively something like beech or cherry would be fairly homogenous and the sort of thing people actually plane in their woodworking.

 

[Anonymous]

I tried a similar test once. The completed article is here http://www.woodcentral.com/cgi-bin/readarticle.pl?dir=handtools&file=articles_325.shtml. I was concerned with getting the best finish from a Stanley plane. I tried various hardwood species and found: (drum roll please) the best surface was obtained with a sharp blade :lol: . It made no difference what the blade thickness or composition was as long as it was sharp. Now different blades stayed sharper longer than others, of course.
As far as edge wear, Brent Beach has done some excellent studies comparing many different blades http://www3.telus.net/BrentBeach/ with accompanying microscopic pix. Brent's studies also show the different ways different alloys wear. Although he wasn't concerned with the finish, his pix show how the finish could be affected by the wear type.
Lyn Mangiameli did a study on high angle planes and the surfaces they produced http://www.estimatortools.us/LJM/hiangle.htm that may also shed some light.

I look forward to hearing your findings. The most difficult part, IMO, is producing a measurable result, especially if you are trying to compare the finish on planed wood. As Lyn found and I concur, the steel alloy and/or blade thickness matters very little as far as finish quality.

 

[Anonymous]

Shady,

MDF is very anisotropic. Notably, it is made up of layers of differing density. Please don't use this!

I heartily recommend some soft maple. It is quite hard despite the name and produces a lovely finish with a sharp iron. Alternatively something like beech or cherry would be fairly homogenous and the sort of thing people actually plane in their woodworking.

I agree with this. I could most easily see surface quality by using a piece of straight grained hard maple. A freshly sharpened blade would leave a highly reflective surface. I thought about trying to use a photographer's light meter to measure the variation in reflectivity as a way to document the results but concluded it was immaterial as a practical matter.

 

[Keith Smith]

Shady I have just been testing some plane blades,unfortunately I don't have the sort of microscopic set up that you have so I had to concentrate on the finish produced.

One thing that struck me was how durable the better blades are compared to the cheap Stanley/Record blades. I was hard pressed to take much of an edge off the L-N. I tried maple then MDF, in the end I used ply. I know it isn't an entirely consistent material but I also wanted to see how easily the blades chipped under duress. I did a considerable amount of planing and kept swapping the planes to even up the results.

Good luck with your tests, I look forward to seeing your results.

Keith

 

[Rob Lee]

I'd welcome any comments on any of this... Seriously interested now...

Hi Shady -

I'd echo the cry to "skip the MDF" ...by all means pick a homogeneous wood - but use wood....

When we did the same testing (results as of yet unpublished 8) ) - we took images at 1000, 2000, 5000, and 10000 cuts... all cuts 6" long...

Most important - chose the bevel angle to suit the wood you're cutting....a type 1 chip failure will not give you the results you're looking for - ensure you're getting type II (wood failure at the blade edge - not ahead of it...)...

Ensure the surface finish on all blades is equivalent - harder blades will take more work to get to the same level...

Take equal numbers of cuts in an equal time on each blade - heat buildup affects wear...

If your Cryo/non-Cryo comparison is on A2 steel, I can possibly save you some time by saying we could observe no difference in wear characteristics in our testing - with multiple blades, from multiple manufacturers....

Have fun - and be be sure to use both arms equally... (don't want one bicep appreciably larger than the other now....) :lol:

Cheers -

Rob

 

[Noel]

Shady, check out Aimee Fraser's article in FW early this year or late last. Although her tests compared sharpening systems as opposed to blade wear it should be of interest to you as well plenty of microscopic pictures. Let me know if don't have access to it.

Noel

 

[Chris Knight]

1000, 2000, 5000, and 10000 cuts.

Rob,
Just guessing here - the Incredible Hulk is on your payroll? :lol:

 

[Keith Smith]

Lets see, 9 irons, 10,000 strokes per iron then repeat to verify results. 180,000 strokes at one second per stroke, its only 50 hours :roll:

Shady if you start now you can have the results by the new year.

That is why I used ply.

Keith

 

[Shady]

Ha ha ha - my thoughts exactly Keith.... :wink: Interesting advice folks, and thanks for it all...

OK, since even in the interests of analysis, the MDF word makes you all shiver and cringe, I'll drop it in the first instance... While appreciating the need for statistically significant results, minor issues like putting food on the table and seeing the family for the next 6 months preclude me looking at 1000's of passes per plane.

I also appreciate the point about reducing as many variables as possible - in several cases, these blades will force me to use different planes, which is an immediate issue. However, I'm doing this essentially for personal interest, and to see if any surprises 'leap out' - if they do, I'll focus on those particular blades and try to work out why.

Rob - I reckon your point about heating may well be another significant wear factor. I don't intend to do anything other than plane 'in my normal fashion', because that will generate the sort of heat these blades have to cope with in a normal environment. However, given the extreme thinness we're aiming for at the tip, it would be fascinating to know what temperatures are generated in normal use: I'm now wondering if it gets hot enough to start causing tempering issues. Obviously we don't all smell scorching as we plane... :shock: , but is there any evidence that there might be enough pressure to heat and thereby damage (say) the first micron of the blade steel? Probably not assessable without a serious lab setup. Before you all laugh at me, I'm just remembering that school physics demo where the teacher showered my arm with sparks - no pain because of the relative thermal 'reservoir' of my arm vis a vis tiny little sparks, despite them being white hot.

Roger, thanks for your links. They're useful - I'd seen them all except Brent's before, but the info is all from exactly this sort of desire to try and put some analysis into our 'art'. Anyway, I'll go and play, and see what comes out of it all.

So - I'm now thinking about a test rig consisting of a bucket of cooled carborundum grit, with my blades mounted to a slow spinning grinding wheel that pushes them through it.... :roll: (the problem is, I really am...)

 

[Alf]

While appreciating the need for statistically significant results, minor issues like putting food on the table and seeing the family for the next 6 months preclude me looking at 1000's of passes per plane.

Well if you're not going to do it properly...

Obviously we don't all smell scorching as we plane... :shock:

Ah, slow worker are we...?

So - I'm now thinking about a test rig consisting of a bucket of cooled carborundum grit, with my blades mounted to a slow spinning grinding wheel that pushes them through it.... :roll: (the problem is, I really am...)

This man needs help as a matter of urgency!

I'm sorry, I can contribute nothing helpful to this so I've stuck with what I know - bad jokes.

I'll be interested in the results mind, I just won't understand them...

Cheers, Alf

 

[Anonymous]

When we did the same testing (results as of yet unpublished 8) ) - we took images at 1000, 2000, 5000, and 10000 cuts... all cuts 6" long...

Most important - chose the bevel angle to suit the wood you're cutting....a type 1 chip failure will not give you the results you're looking for - ensure you're getting type II (wood failure at the blade edge - not ahead of it...)...

Ensure the surface finish on all blades is equivalent - harder blades will take more work to get to the same level...

Take equal numbers of cuts in an equal time on each blade - heat buildup affects wear...

If your Cryo/non-Cryo comparison is on A2 steel, I can possibly save you some time by saying we could observe no difference in wear characteristics in our testing - with multiple blades, from multiple manufacturers....

Have fun - and be be sure to use both arms equally... (don't want one bicep appreciably larger than the other now....) :lol:

Cheers -

Rob

This sounds fascinating and I'll be good and wait for the publication instead of asking 1,000, 2,000, 5,000 or 10,000 questions .

Just a couple of generic questions. I assume the subject of this test is blade wear? The comment about heat buildup is interesting, especially when the cut is only 6" long. The only time I have noticed blades getting warm to the touch is when edge jointing or scrubbing (long fast passes, heavier cuts). How fast are you pushing these planes?

 

[Rob Lee]

(snip)

Just a couple of generic questions. I assume the subject of this test is blade wear? The comment about heat buildup is interesting, especially when the cut is only 6" long. The only time I have noticed blades getting warm to the touch is when edge jointing or scrubbing (long fast passes, heavier cuts). How fast are you pushing these planes?

Hi Roger -

Test is blade wear of A2....but also the mechanics of edge breakdown.

Our test fixture (automated) can be run at variable speeds - we had to slow things down so that heat was not a factor...as we ran it continuously... speed would be a "normal" user speed...not exactly sure of the FPM just now....

Cheers -

Rob

(just home from Toronto - and have an out-of-town hockey tournament tomorrow...)