Matching grinding wheels of different diameter

[Ken S]

Jan,

I would like to see a map showing where apostrophe is still used in the English language. I dont think there would be many areas showing in North America.


Thanks for your kind words about my oversize wheel thoughts. I have read that the other wheel company was given ten inches instead of 250mm as the design spec, hence the slight oversize.

Truing the wheel will eventually solve the oversize dilemma.

Ken

Ken, I was delighted to read your advice for oversize wheels. 

You showed almost the same inventiveness as Wootz by internationalization of its script. 

Jan

[Jan]

Ken, you are generally correct, English speaking countries use decimal point. The exception is South Africa. In Canada they use decimal point when they are using English.

I do not have the exact figure, but the majority of people in the world use decimal point, however this is given by the fact that China and India do.

Jan

[Ken S]

Jan, I must not have been clear. I was referring to the all too common (lazy) habit of many English speakers of ignoring the apostrophe in contractions. "Don't", a contraction for " do not" becomes just "dont". I am sure that as a native Czech speaker you were taught proper English. Sadly, too many of my countrymen have forgotten how to properly speak our own language. 

Ken

[Jan]

OK Ken, sorry for my misunderstanding. 

Jan

[Ken S]

"Dont worry", Jan. I was just commenting on the state of English by native speakers.

Actually, your comment about the use of commas and periods in math is fascinating.

Ken

[Jan]

Wootz, I again dealt with your program for matching grindings wheels of different diameters and I would like to propose to appoint you and Dutchman for Professors!  http://forum.tormek.com/index.php?topic=2969.msg15686#msg15686

The reason is simple, I have compared your script with a similar formula published by John Verhoeven and I found that yours works much better. (Experiments on Knife Sharpening by John D. Verhoeven can be downloaded as PDF from https://www.wickededgeusa.com/wp-content/uploads/2012/10/knifeshexps.pdf)

The study referenced above presents in appendix 2 a formula (Eqn. 1) derived by R. Homer, which is biased by several degrees. Instead to found a bug an empirical correction constant was introduced that approximately corrects the bias.  (The problem is not in its own calculation, but in oversimplified geometry of knife sharpening using TORMEK jig and USB.)

Because both authors are emeritus Professors, I think that you deserve to be Professors also. 

Respectfully yours.
Jan

[wootz]

Thank you, Jan. Knowing your university background, and how meticulous you are, I and Dutchman should hold your praise in high regard.

I understand Verhoeven couldn't get the formula predictions work because of the knife jig offset from the centreline, and actual results varied with the knife thickness. Verhoeven attributed this offset to a manufacturing flaw. If he realized it is on purpose, he would have mentioned the thickness of the knife blade in his work.
No wonder though he was mistaken, as Tormek doesn't clearly state the lower jaw offset from the jig centreline, and regular users centre the blade in the jig by guess-work.
It was your, Jan, elegant solution to find out the offset is to center 2.5mm thick blade, which got further confirmation in Tormek's Improved Knife Jig description saying "Knife 2.5 mm thick" http://tormek.com/international/en/grinding-jigs/svm-45-knife-jig/
Any knife outside this ideal thickness would require a correction to the formula to get the predicted angle.

Well, we all understand the practical importance of these calculations is not in achieving the exact target edge angle, but in maintaining the same grinding angle as we move the blade to a stone of a finer grit, and to the honing wheel, as this is the only way to get it sharp.
Since the script was developed, I use only it to set the same grinding angle by the Universal Support height as I move from the #220 grinding wheel to finer wheels, and then to the honing paper wheel, and always get ultimate possible sharpness. I can't even remember when I last used AngleMaster or marker for adjustments.

[WolfY]

Jan, I must not have been clear. I was referring to the all too common (lazy) habit of many English speakers of ignoring the apostrophe in contractions. "Don't", a contraction for " do not" becomes just "dont". I am sure that as a native Czech speaker you were taught proper English. Sadly, too many of my countrymen have forgotten how to properly speak our own language. 

Ken

I think the reason of not using the apostrophe is purely laziness to change keyboard layout or fast writing. And now it got so common and accepted, so it is OK for the new gen as they don't know else.

[Jan]

Wootz, I have appreciated your answer! 

The original Dutchman approach involves a small approximation concerning the way we measure the distance between the grindstone and the USB.

Your approach, Wootz, is not burdened by this small approximation. For this reason your script provides even more accurate results than the Dutchman tables even though you are using the Dutchman formula also. 

Jan

[Ken S]

I appreciate having the technical back up of the Forum Mathematics Department. Being able to be more precise than might be needed helps true up the whole process, just like working with a well trued grinding wheel.

I do think we need to differentiate between precision and consistency. I believe most users will be quite content as long as the bevels appear to be consistent and the bevel angles visually approximate the desired fifteen degrees or or whatever the desired angle is. (We have an idiom in English, "It looks good from the road")

While we can not achieve exactly our mythical fifteen degrees, I am in favor of anything material or mathematical which helps us approach it.

Ken

[RichColvin]

Ken,

I agree :  consistency is more important than accuracy for me. 

Kind regards,
Rich

[Ken S]

Rich,

I agree about the importance of consistency, but I would temper that belief with a very healthy regard for accuracy. I think a good marriage of the two is the engine cut hash marks in the Starrett rules. The divisions may only be for 1/2 millimeters or 1/64 or 1/100", however the accuracy of the spacing is considerably more precise. We don't need a micrometer for a rule measurement, but it is nice to have a very good rule.

I think it is always a good idea to have a sense of the measurement accuracy (tolerance) for the job in hand.

Ken

[WolfY]

I agree with you all
Can we agree to always use Metric and Swedish rules for numbers and measures?
At least it is consistent and politicly correct as we are in "Tormek environment"

[Ken S]

WolfY,

I agree with you about using metric measurement. After all, Tormek is an almost all metric. For some reason, the screw on feet of the Tormek Work Station have 5/8 x 11tpi threads. I have no clue why a Swedish vompany chose to have a product made in Germany have feet with imperial threads. However, I agree that the Tormek is essentially a metric machine and logically forum measurements shoild be primarily metric.

Is anyone uncomfortable with that?

I would prefer to use Eastern Danish Rules for Numbers and Measures. I am joking, as I have absolutely no idea of what Swedish rules for numbers and measures are. Would you please explain.

I will hold out for one non metric measurement, the British pint. (It's even in the handbook!)

Ken

[WolfY]

Ken,

I was exaggerating with the "Swedish" rules and numbers
But for example: the comma for thousands and decimal is like this: XXX XXX,XX
Today's date is 2016-07-01 although it's not relevant for us
Don't remember other rules that really are relevant or important