Messages

[doesn't matter, as long as it's >= the Projection length]

Please pardon me if it's a stupid question - is the change in a protrusion length of a jig+blade changes the edge angle?

Hello,

yes, changing the protrusion length also changes the edge angle, it is always necessary to specify the correct protrusion length for the calculation.

The angle used for the Angle Cube is set with the same parameters as any other method (Projection Length, Sharpening Angle, etc.), so I guess the answer is Yes, but it is accounted for.  (The length of the platform you set that Angle Cube on doesn't matter, as long as it's >= the Projection length.)

A small correction, just to be sure - the platform you set the Angle Cube on must be placed over the USB and the highest point on the stone (= must be long enough).

jvh

[NOT highlighted]

Hi there!

Amazing work with the Calc! I just started using it and I have some newbie questions.

I just did a first knife with it and the calculation was off by a bit. Here is the calculation:
I have two Tormeks, Machine 6 is one with Front Vertical from Colvin. Target angle was 15dps, protrusion: 144mm.
SG-250 support height was 172.19, SJ-250 on Frontal was 97.70. And that was off - I had to raise the support ~2 rotations to match the angle, according to sharpie. I wonder if something in my calculations is visibly off.

Hello,

cbwx34, thanks for your help, you've nailed it again. 

As cb mentioned in post #101 (and #99) - In the Settings sheet, change the value in cell F26 to 20 (or less). This cell contains the Minimum FVB distance value, and any lower value is ignored because it is assumed to be an input error.
The problem was that the calculations were performed with a value of F = 24.4 mm.

I wonder if it good idea to "split" the Jig Projection Length into protrusion from tip of KJ-45 to the edge of the knife like this:

The length of the KJ jig is fixed, so it would be much easier to measure only the knife sitting depth.
If I am guessing right, the H1 on Jigs page is what I need:
But that one is protected, so I wonder if I am mistaken.

It's actually a great idea to measure the knife sitting depth in the KJ-45 jig and the Projection length correction X+ is designed for just that purpose.
I don't currently have the KJ-45 on hand, so I don't know the X+ length, but it will be the exact length that is NOT highlighted in your picture. The highlighted part of the dimension "Jig projection length X" (= knife sitting depth) will be entered into the input cell.

The cell with "Projection length correction X+" is protected, but to modify it just unlock the Jigs sheet, as CB also wrote...

Would it be cool to put together an IR distance sensor, Arduino, some LCD screen and 3D print a mount that goes here:

Nice idea.

Perhaps. That height measurement feels bit clumsy. There is no fixed point to measure against. I would gladly pay up for a reliable, fast and easy way to know the support height.

Why don't you mesure USB to stone ? It's an easy measurement to take as you basically measure to the closest point of the stone, and you don't need any intermediate measurements that might compound the error....

If there is a chance of a digital height reading, the USB to body measurement implementation is easier than USB to stone...

jvh

Hello cb,

good thinking... 

I'll just add a few comments:

- You don't have to keep flipping values, but you can use also other section for knife 3 to 6 to continue.
- If you are in doubt about where the USB is, you can always measure it with a caliper as the height is also calculated.
- Whether it is advantageous to set the height in one direction (from lowest projection distance ) is a question for everyone. When using a single stone, probably yes, but when grinding on multiple wheels, it depends on their diameters whether the USB goes down or up. I number each blade so I don't get confused, because I progress from blade number 1 to the last blade, then switch wheel and progress again from blade number 1 etc.
- If I need to adjust the height by more than 15 mm (10 turns of the nut), I use a 15 mm spacer to quickly adjust 10 turns without counting, then adjust the rest.
- In my experience, setting the wrong height can only happen by human error, otherwise there is no accumulation of errors over time. Setting by turning Tormek nut  together with diffferent wheel diameter compensation is IMHO incredibly accurate. The first/default height setting may seem to be a weak point, but a slight deviation here does not affect the consistency of the other steps.

jvh

[Version 3.10 has been released]

Version 3.10 has been released (available as Public and Full version)

Main news:

• Wheels [New sheet]
  New sheet "Wheels" which contains a list of available wheels for various Tormek grinders (T-8, T-4, etc.) and possibly for other ones.
  
  
• 
  Revised Wheel table on TormekCalc sheet
  Wheel selection is now done using the drop-down list in the Wheel table on the TormekCalc sheet. The wheel specifications (image, grain size and nominal diameter) are automatically loaded from the Wheels sheet. This change allows an unlimited number of suitable grinding and honing wheels for different machines  to be added to the list and gives the user the ability to select the wheels used and specify their order. This change does not affect the actual diameter D values, which need to be entered/updated in the same way as in previous versions.
  Automatic image loading features are not supported in Office/Excel 365. There is no known solution other than static layout (as in previous versions). Due to these limitations, Excel 365 is no longer supported as of version 3.10.
  
  
• 
  Jigs sheet update
  Specifications for KJ-45 and KJ-140 have been added to the Jigs sheet (default jig diameter = 11.8 mm).
  The "Order in drop-down lists" column have been added in the Jigs table which you can use to change the order in which the jigs appear in the drop-down lists. If no order is specified, the jigs are displayed in the same order as in the table.
  
  
• 
  Hardness sheet
  Hardness info tables are now available  in the Public version.
  
  
• 
  Data import
  Data import from previous TormekCalc versions is now available  in the Public version (import from 2.63 onwards).
  
  
• 
  Backup
  Backup function is now available in the Public version.
  
  
• 
  And much more...
  Internal changes, corrections, bug fixes, comments, etc., more in the Change history on the VB sheet.
  

Download link is in the first post.

Enjoy!


jvh

Note: All users of the full version should have received the new version soon, if not, please send me a private message or email. Some messages are being returned to me as undeliverable, probably due to more aggressive anti-spam filters.

Maybe I'm missing something, but it seems to be that it would be so much more useful to have a 250mm leather wheel, as opposed to the Tormek 215mm wheel, at least for knife sharpening.  In order to use the 215mm wheel with any knife over c. 3.5", you have to remove the water trough and grinding wheel and replace the wheel with the spacer and nut.

But with a 250mm wheel, you could avoid that with most knives -- up to the typical 8" chef's knife -- without removing the grinding stone.  That's because, when you're honing towards the grinding wheel, you have to start lifting the handle before it would hit the wheel.

As an added benefit, you could grind and hone with very little adjustment.  You could use a FVB, grinding away from the edge, and then just flip the USB to hone.  At most you'd need a couple turns of the micro adjust to account for stone wear.

Hello,

although using a 250 mm honing wheel seems like a good idea, I would like to remind you of a phenomenon that occurs when using wheels with different diameters. This also applies to traditional stones, which decrease in diameter over time due to "unsharpened" material at the edge heel, which then interferes with honing.

This phenomenon was first described here by Gilles: https://forum.tormek.com/index.php?topic=4326.0
Video with detailed description is here: https://www.youtube.com/watch?v=h_qRUvSvcLQ


jvh

Hello,

something like that?

SVD-110: https://forum.tormek.com/index.php?topic=4181.msg32135#msg32135
Drawings:  https://forum.tormek.com/index.php?topic=4181.msg32140#msg32140

You can define any custom platform jig.
Correct jig diameter and projection length (from defined point) are enough for calculations, Reverse calculation of the set angle on tool rest can be done on BevelCalc sheet.

At TormekCalc since v2.63 

jvh

I've not dealt with chisels much, and they're pretty easy to set with the AngleMaster, (that nice flat side... aaahhhhh)    but I figured out, based on some of the TormekCalc info, that you can use the Calcapp app (and I'm guessing most of the other apps) to set the USB height.

You set the Jig Diameter to 49.2 and add 30.1 to the measured Projection Distance.

Glad this came up... learn something new every day!   

p.s. Hats off to jvh!  And I might add, if you can, send jvh a donation and get his Spreadsheet.  Totally worth it, even if you only use it as a reference to some of the other calculators, or for example, a way to document your sharpening.

Thanks cb.

Just for clarification, the public version of TormekCalc is still available for free, just send me a PM for the download password.

jvh

Hello,

I fully agree with tgbto:

...compare two knives with the same apex angle...

I remember a similar discussion - What happens when sharpening a convex blade on a Tormek (if the angle is followed exactly) is shown here: https://forum.tormek.com/index.php?topic=4507

I recommend to draw the theory in CAD, then it is possible to simulate exactly what happens, and how the grinding method / grinding angle affects the result.
I'm not saying that there is no difference between convex and hollow grinds, but you need to compare comparables (same apex angle) and look at the variations that exist between these grinds. If you draw it, it doesn't look that bad, personally I would focus on the apex angle and blade thickness parameters. It doesn't make much sense to me to do a convex grind on thin blades or full flat / high flat blades, but let each person grind to their own...

jvh

Hello,

since there were different results, I checked the TormekCalc outputs in parametric CAD and I can confirm that the results posted in Reply #4 are correct, see attached images.

For completeness, I should mention that there is a special module in TormekCalc called BevelCalc for back calculation of the grinding angle (from different USB heights, different jigs, etc.).

jvh

...
To overcome these issues I have derived a new method of computing the constants mathematically which is quick and easy and requires no particular skill. As a bonus the math/s used also implicitly caters for any variance from perpendicular of the support bar and mounting at any height, which is particularly useful in home-made bar mountings made from off the shelf components not precision engineered, such as those used in slow-speed honing setups.
...

Hello Andrew,

nice idea, thanks for sharing. I'll test it later when I have time...

jvh

I've been re-sharpening my chisels a lot lately.  I think there must be a way to use the TTS-100 Turning Tool Setter to make the sharpening process faster.  Using the diagrams below, I'd like to come up with a formula for the projection based on the desired angle.

There are 3 key measurements:
  * When using the B hole on the TTS-100, I measured that the USB is set to be 17 mm away from the grindstone. 
  * The distance from the USB to the SE-77 where the top of the chisel is held is 25 mm.
  * The width of the SE-77 is 35 mm.

The values I measured for P (projection) are:

   20° bevel angle, P = 49 mm
   25° bevel angle, P = 44 mm
   30° bevel angle, P = 38 mm

But, I would prefer to have a formal to calculate this.  So this is a request of my geeky friends to help me find such a formula.  Anyone?

Hello,

you can do such calculations in TormekCalc using What-If Analysis / Goal Seek, see pictures.

Calculations for SE-77 jig are supported, constants are stored in Jigs sheets, projection should be measured as in your drawing.
Since t USB is measured in TormekCalc from the top of the USB, the desired value is 29 mm (17+12 mm).

I calculated with a wheel diameter of 250 mm and I got different results for the given angles.

Feel free to ask if you need further information.

jvh

[+0.04/+0.06mm]

On YT is a video that the diameter of the shaft is not 12mm +0,000. It is 12,001 12,01 so the CBN discs Schleifjunkies is selling doesn´t fit to custumer machines.
In my sight this is a scandal.
For machinebuilder there is a ISO standart, called ISO Einheitswelle / Einheitsbohrung. (Sorry, didn´t find a translation.)

Hello,

Has anyone had a similar problem with Tormek's diamond wheels? Are the manufacturing tolerances of the shaft known?

I don't think it's fair to complain about the original shaft when a non-original wheel is fitted to it.

I found that the hole in the original diamond Tormek wheels should be 12.00mm +0.04/+0.06mm diameter (not verified), if these tolerances are correct, the problem is clearly with the non-original CBN wheels dimensions/tolerances, not on the Tormek side...

The +0.04 / +0.06 mm tolerance zone does not correspond to any standard tolerance class (ISO 286-2), which may be the answer to why a standardized fit is not used.

jvh

---<snip>---
... but only a readjustment of the height using the micro adjust nut, which is threaded with a given pitch of 1.5 mm.

jvh

Mine have a 1.75 mm pitch? 

Hello,

that's weird, even the manual mentions graduation 1 part = 0.25mm, which corresponds to a 1.5mm pitch.

Where and how did you measure the pitch?

jvh

I use TormekCalc² a lot, but I stopped bothering with these constants as I find measuring from top of Usb to top of stone (T USB) much easier than referencing an approximate point on the stone.

Hello,

this is more about personal preference. I find it easier to measure from the top of the USB to a given spot on the T-8 body than to the surface of a rounded stone. If you're comfortable with the second method, that's completely fine.

From my point of view, based on the tests I have done, the two methods are fully comparable, but of course, when measuring on the body of the machine, you need to have accurately measured constants. While this may take 1 or 2 hours, it is only a one-time task because the constants for the machine don't change anymore, so I see no reason not to invest a little time in it.

Anyway, measuring between steps is a thing of the past for me, now I only set the initial USB height, then I adjust the height using the defined number of Tormek micro adjust nut rotations. It's the most accurate method I've found, and together with a compensation layer for different disc diameters it completely eliminated the need to make additional USB height corrections.

If the initial height is not set completely accurately, the resulting angle is indeed slightly different, but it does not affect the grinding process in any way, because there is no longer a new height measurement, but only a readjustment of the height using the micro adjust nut, which is threaded with a given pitch of 1.5 mm. Simple, precise, fast.

And this method with fewer measurements is less prone to measurement errors, as it is certainly easier to accurately adjust the height 2x than 9x.    But even that doesn't mean that everyone can do it their own way, the way they prefer.

jvh

I have the FVB from Knife Grinders.

Martin

Hello,

then your machine setup should look similar to the "Machine settings.jpg" image (Settings sheet).

Since this setting is selected from the usual values measured on the T-8 machine, it may not be completely accurate. Therefore, I recommend remeasuring all constants and correcting them if necessary.

Don't forget to change the machine settings under the grinding wheels afterwards - see "Wheel - Machine.jpg".

jvh