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Kitchen Scales=Feedback Mechanism

wdwrx

Well-Known Member
I tried an interesting thing the other day. I used a kitchen scale (Bart's idea from The Sharpening Academy) to benchmark the pressure I was using at bevel setting stage. I was quite surprised at the amount of pressure 200 +g's really is. Considerably more than I'd ever used before. But I didn't stop there. I carried on honing on top of the kitchen scale, and I noticed I had all kinds of pressure variations throughout my strokes.

Honing on the kitchen scale really helped me normalize my strokes by showing variants in pressure from stroke to stroke, and through different parts of the stroke. I've learned to equalize the pressure used on both my pull strokes and push strokes. I guess eventually uneven hone wear would have grassed me up but at least I'm a little more aware. It also helped me to correct the habit I have of subconsciously bringing more pressure to bear as I go.

I thought this might prove to be a good idea for other noobs (like me) who are trying to learn without the benefit of one-on-one mentoring.

I've posted a similar thread on SRP to this effect, but it didn't seem to get a very warm reception( :confused: )...;) So I thought I'd post it in a forum of a more scientific bend.

Thanks for yet another great idea Bart!
 

Bart

Well-Known Member
You're welcome Chris.

I included the scale readings, because it's the most logical way to say something about pressure. I mean "can of vegetables" is a good attempt (yes I quickly read your thread on SRP:) ), yet not all that precise, as they come in different sizes.
I didn't include the readings to promote actual honing on the scales, but I still like your idea, as long as you don't become too focused on it. I think pressure is a "ball park" kind of thing.

But 1000g?!?? That's over 2 pounds and it seems an awful lot to me. I never go anywhere near that pressure for razors. (My readings were zeroed with the hone and the razor on the scale), as I think it would flex a typical hollow ground razor considerately. Not that it must necessarily pose a problem for the final outcome, but let's look at a picture:


This is a razor I honed for one of our members a while ago. The picture is shot after the bevel stage. You see the Coticule scratch pattern I put on it, which typically had the "sand-blasted" look. I didn't use any tape. So what the hell are those coarse scratches between my bevel and the razor's body doing there? There are only 2 explanations possible that I can think of:
1. someone previously used a lot of pressure on a coarse stone. The razor flexed and the bevel "flatted out".
2. someone took the razor to a grinding wheel, which caused a wider than normal concave bevel.

Which of those 2 sounds most likely to you? ;)

Anyway, when I collected my scale readings, I was pleasantly surprised to see that numbers didn't fluctuate much and were fairly consistent during the forth and back strokes. I don't do short circles, so I have no readings for that.

On an entirely different note, I am sure that the optimal pressure range is influenced by the type of hone. The logic at first sight seems to dictate that you start with more pressure than you finish with. While that may hold some truth in general, there are several factors that call for reconsideration. On a DMT-C (325 grit) for instance, I will be very careful with pressure, because it will not only rip apart the apex of the bevel, but also introduce stresses into the steel that might interfere with your intentions later in the honing process. Moreover, DMT advices to let the hone do the cutting. Coticules on the other hand seem to allow much more pressure than the average synthetic hone, even during the finishing stage. But even then, it really depends on the purpose. With Unicot, the edge is tipped on a very thin region at the apex of the bevel. If you apply more than minimal pressure at these circumstances, you will be unpleasantly surprised. With, on the other hand, Dilucot, the edge it resting on the entire bevel, and a bit of pressure might be called for. I always finish with lightest pressure first, but trying a bit more is one of my standard strategies for when it doesn't end up as well as I know it can.

For several months I have 2 barber hones awaiting to play around. I've only tried them once so far, which is way too little experience to say much about them. But they sure don't seem to condone any pressure at all. Just sharing to illustrate how much difference there can be between hones.

I think it would be great to have a hones database, with directions for use that fit each hone listed: range of use, recommended pressure zone, etc. Although it's clearly not in every one's interest to demystify these aspects of honing. We've had several posts in various threads made by members who were very surprised to find out that certain "holy" rules seemed far less holy than they thought.:rolleyes:

Kind regards,
Bart.
 

wdwrx

Well-Known Member
Lordy Bart! How on earth do you find the time to create such eloquent, thoughtful and well reasoned responses?:thumbup:
Thank you.

Typing is a long and arduous process for me so I'll keep it short.;)

What you say makes perfect sense in regards to different hones. I have used a bit of pressure on my DMT equivalent, but only after bread-knifing. With a belt sander.

I thought 1000 g was a little excessive too. I tried, but 400g was as heavy as i dared, and even that was only for about 2 strokes. 300 g and less was what i settled near for bevel setting, and that was only for about one set of 10 half stokes. It's just what felt about right.

I found i have a natural tendency to want to be at about 80g. At that level, the hone is talking to me, and it seems to invite that much pressure. It takes a bit of positive input to reach that level of pressure, which seems to stabilize the edge against the hone, so i have a feeling that a lot of people (read: noobs) use that general level of pressure. This is the range I do the dilution stages at, though I do try to lighten up as I go. Does that sound about right to anyone? I'm worried it's a bit on the heavy side.

Now, with that said, I did notice that the final stages I did (over the sink, holding the hone in my hand) were even lighter and smoother and more consistent than the stokes I'm capable of when the hone sits on the table... or the scale:) I could tell the strokes were lighter than anything I was doing before because now I have a pretty good idea of exactly how much pressure I had been using. If I had to guess, I would say that I was able to make fairly consistent strokes in about the 10 or 15g range, compared to 30 to 40G on the table. Holding the hone is something I've only just started to do, but I think that is where I will focus my energies now. I'm ready to lose the training wheels now!

To play devil's advocate, it occurred to me that the use of excessive pressure (which I would say 1-kg is IMHO), and the resulting creation of that extended bevel shown in the photo (if that is actually the case), might actually function as some sort of double-bevel. We could call it the "heavy-cot"! In all seriousness though, it has obviously created a secondary bevel, in much the same way the uni-cot does, just backwards. Or something. Just look at that narrow little strip of freshly honed bevel. Couldn't imagine it being a smooth shave, but it sure would make for a fast hone job. I like to see the whole width of the bevel polished nicely.

Cheers!
-Chris
 

jkh

Well-Known Member
Chris, thanks for posting this. I think the scale is a good way for someone with little to no honing experience to get handle on what is pressure. I agree with Bart, one should be careful not to make the scale a crutch.

Now I need to go get a scale and try this out :)
 

Matt

Well-Known Member
I must say I'm amazed with nearly every Bart's post how much can be said, down to every detail, on this subject.

And also, there are so often some hidden gems in them. :) You could distill a whole new article 'Excerpts from Bart' :lol:

kind regards,
Matt
 

wdwrx

Well-Known Member
Matt said:
I must say I'm amazed with nearly every Bart's post how much can be said, down to every detail, on this subject.

And also, there are so often some hidden gems in them. :) You could distill a whole new article 'Excerpts from Bart' :lol:

kind regards,
Matt

I think he should write a book. He could get rich! and he has the talent. Bart's post are an absolute pleasure to read.
 

tat2Ralfy

Well-Known Member
wdwrx said:
Matt said:
I must say I'm amazed with nearly every Bart's post how much can be said, down to every detail, on this subject.

And also, there are so often some hidden gems in them. :) You could distill a whole new article 'Excerpts from Bart' :lol:

kind regards,
Matt

I think he should write a book. He could get rich! and he has the talent. Bart's post are an absolute pleasure to read.

So very true
I bet he cant half go on in real life (jk)
Bwhahahaha

Sorry couldnt help myself!
Please do carry on

My kindest wishes
Ralfson (Dr)
 
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