Need Advice.

[dusmif]

Hi, I am considering to buy a sharpness testing scale, I found and it seems that it is recommended, the PTA50: now there are at least 3 versions, the PTA50A;PTA50B and the PTA50C, Any recommendation which it is the best to buy and why
in your opinion it is so, please?
Thank you.
Alf.

[micha]

Alf,
the PT50A is sure the best of the three you named. They differ mainly in the processor speed of the scale and its resolution.
PTA 50 can handle 25 measurements per seconds with a resolution of 1 Gram, while, afaik, PT50C does 5 measurements/sec with 25 grams resolution. The B-model is somewhere inbetween.

So if you're determined to buy one, go for the PT50A. It's not a must-have, but sure helps with developing your sharpening methods.
You find a quite concise comparison here: https://www.edgeonup.com/PT50-Series.html
Mike

[Ken S]

Alf,

I have an older version of the B. Same accuracy, one more button to push. I suspect the B is the practical choice for most of us. That said, I don't think the A model was available when I bought mine. Liking overkill, I would probably have chosen it.

Check out bessex.com. It's the forum for BESS and Edge on Up. I've been a member since it began. They are a good, helpful bunch.

Ken

[dusmif]

Thank you Mike and Ken, much appreciate your feedback. One more question, can you test the sharpness of a  Wood Chisel with one of these ?
Another question What is the meaning "25 measurements per seconds with a resolution of 1 Gram"
I tried to look it up, but without success.
Thanks.
Alf

[jvh]

Hello,

why do you need to measure BESS value? I'd rather invest in a good microscope - you'll see what's going on on the whole edge, not at single/few points...

jvh

[dusmif]

Jvh, but will by looking only, one can check the sharpness?
Alf

[jvh]

Jvh, but will by looking only, one can check the sharpness?
Alf

Alf,

it depends. Sharpness for what? For the lowest BESS or for real use?

Sharpness is only one part of the problem. You have to consider also the real use, edge toughness, edge retention, corrosion resistance. You have to remove burr completely.

BESS shows you the sharpness in one point of the edge at a given time. When you repeat the measurement the next day you will get a value ca +20 g higher due to the oxidation of the edge. The BESS value will increase significantly after a few cuts etc.

With a good microscope... what do you think, is it sharp? (And you can still use cigarette paper, hair etc.)
https://youtu.be/QG_z9ynBht8?t=122
https://youtu.be/NXz7WB_qhqk?t=92
https://youtu.be/8LS17P0k4hw

jvh

[dusmif]

That is very interesting,You got a point.  Thank you for sharing.
Alf.

[micha]

One more question, can you test the sharpness of a  Wood Chisel with one of these ?
Another question What is the meaning "25 measurements per seconds with a resolution of 1 Gram"
Thanks.
Alf

Alf,
these "25 measurements" can be a bit misleading. It just means the measured value (finally on the scale's display) is updated 25 times per second. It is an advantage if that happens as often as possible, as the measured force is gradually increased when you move down the blade.  (Imagine, if a scale would just do one measurement per second, you could have cut the thread before the scale even noticed). So a higher rate adds to accuracy.

jvh,
I agree with you that the BESS Tester is just one means of evaluating sharpness, among many others.
Real use, edge retention etc. play an important role, of course. Also oxidation and a the loss of sharpness after a few cuts occur, but are not related to a certain test method.

I can just speak for myself, but the bess tester and a good microscope (thanks for mentioning)  have helped me a lot in developing my sharpening and deburring skills.

Mike

EDIT: Yes, you can measure chisels, too, at least wider ones. But for chisels I think testing them in a "real life" environment is more useful than just getting a BESS value.

[dusmif]

Thank You Mike, that was very helpful.
Alf.

[BeSharp]

Mike Brubacher, the inventor, recommends the PT50B for most users.

[dusmif]

Thank You All for your help and advice, I appreciate it very much.
Alf

[BradGE]

I have the PT50A.   With a do-over I would probably get the PT50-B.  I find I don't put much emphasis on the 1g resolution (for example is 80BESS really better than 84).   Also so many variables with BESS testing (thread tension etc).

After a sharpening session I'd definitely want to know if I was more at 125 or 85, but not so much whether I'm 90 or 92 BESS...

[tgbto]

Re the BESS tester - which I purchased because I'm not a reasonable person, and also because it intrigues me - there is one thing I can't seem to wrap my head around :

Thread tension obviously plays a key role in the result, as the tighter the thread, the earlier it will break.
I've seen attempts at standardizing thread tension by hanging 100g weights and such, which is fine.
But unless I don't use it properly, it seems to me that the tightness of the screw plays a key role in thread tension. So much so that it seems one can break the thread just by tightening the screw. So you'd obviously get much better BESS values with a thread that's on the verge of snapping.

Did I miss something ?

Cheers,

Nick.

[micha]

Nick,

you're right, that's sure something to be considered.
It's one of the reasons why comparability of results from different person's testing might be somehow limited.

However, in a reasonable range the effects are probably not that serious. If you use the PT50 to compare your own results you will probably have a somewhat consistent technique of tensioning and tightening. The manual advises to not overtension. Light pressure for the screws is also explicitly mentioned.

But I think one could deliberately affect results by extreme overtensioning the line or overtightening the screws.
I think we're reasonable enough not to do so (despite of not being reasonable enough to avoid buying a BESS tester )
Mike