On the (amazing) Tormek Calc2 spreadsheet, what is cell 13 (Frontal vertical base offset F [mm]) measuring? Is it what I show in the attached picture?
The note references marks on the rod, I don't see any marks on the setup I have.
Thanks
Martin
Quote from: MartinC on February 21, 2022, 10:38:33 PM
On the (amazing) Tormek Calc2 spreadsheet, what is cell 13 (Frontal vertical base offset F [mm]) measuring? Is it what I show in the attached picture?
The note references marks on the rod, I don't see any marks on the setup I have.
Hello Martin,
yes the measurement position is correct, but it also depends on the type of FVB and its dimensions (constants), namely FVB body thickness, constant VF (and constant VH).
What type of FVB do you use (manufacturer)?
Reference marks on the rod are on my version of FVB - see https://forum.tormek.com/index.php?topic=4129.0. They are used to quickly adjust the position of the FVB
jvh
I have the FVB from Knife Grinders.
Martin
Quote from: MartinC on February 22, 2022, 01:37:28 AM
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
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.
Quote from: tgbto on February 22, 2022, 08:27:08 AM
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.
And that method, with less variables, is less prone to tolerances. ;)
Quote from: tgbto on February 22, 2022, 08:27:08 AM
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 guess my view has changed a bit... I now simply view the calculator(s) as a better way to set the angle for knives, mainly because it accounts for the blade taper that the AngleMaster does not. This taper can result in an error of several degrees. Also to me, the calculator is more consistent and easily repeatable, whether you measure to the machine or directly to the wheel.
But I really don't care, nor do I think it's necessary, to try and be "super accurate". If there are measurements available for the model of the machine (or FVB) you use... for example the defaults in TormekCalc, I would use them without issue. I doubt there's enough difference between machines to matter, (and probably more places of error in this than small differences in the machine). Just make sure they match what you're using... (mainly the FVB setup).
Quote from: jvh on February 22, 2022, 12:36:06 PM
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.
I don't see any harm being done by following this logic. My time is my own.
Quote from: jvh on February 22, 2022, 12:36:06 PM
---<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? ???
Quote from: highpower on February 22, 2022, 08:34:14 PM
Quote from: jvh on February 22, 2022, 12:36:06 PM
---<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
Quote from: jvh on February 22, 2022, 10:06:05 PM
Quote from: highpower on February 22, 2022, 08:34:14 PM
Quote from: jvh on February 22, 2022, 12:36:06 PM
---<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
My apologies Jan. I was going from memory and I obviously mis-remembered what I had measured them at the first time. :-[
I'm afraid I suffer from a condition known as 'old man's disease' or C.R.S. (Can't Remember... Stuff.)
I just got out my calipers again and sure enough, 1.5mm between the (truncated) crests of the threads on my USB.
This chart may help clear up the 1.5/1.75 mm thread pitch confusion:
https://www.boltdepot.com/fastener-information/measuring/metric-thread-pitch.aspx
As shown, the pitch for the standard twelve mm metric thread is 1.75 mm. This is the thread size used on the "dry end" of the Tormek shaft. (The shafts of the T8 and T4 have the same diameters and thread sizes.) It is the same thread that was used on the "wet end" of the pre EZYlock shafts.
Tormek wisely chose to use the metric fine pitch thread for the EZYlock. Using the six divisions of the microadjust nut, even mere math mortals like me can do the calculations in our heads. From a known point, raising the microadjust four numbers (divisions) using 1.5 mm for a full revolution is 1.0 mm. Calculating one sixth of 1.75 mm would needlessly complicate the equation.
The EZYlock uses the same principle as a micrometer. The shaft of the standard inch micrometer has a 40 Thread Per Inch thread. The standard metric micrometer pitch is 0.5mm. The barrel of inch micrometers is divided into 25 divisions, making each division 0.001". The barrel of metric micris micrometers has fifty divisions, making each division 0.01mm.
Incidentally, I use Dutchman's technique of measuring metween the top of the support bar and the grinding wheel. In my case, I have a T7 and a T8. This method permits me to use a single kenjig with either machine with no extra calculations.
Ken
Go to the main forum page, and search for the word acme and you'll find several threads (no pun intended) on this topic. ;)
i'm just hobby, not a professional grinder, but i've got apps from Knifegrinders and SchleifJunkies too and when comparing it, i have to say, none of them is so good as TormekCalc. it worth the money you spend for it. it is a great help for grinding. thank to JVH.
Quote from: Ken S on February 23, 2022, 10:56:58 AM
This chart may help clear up the 1.5/1.75 mm thread pitch confusion:
https://www.boltdepot.com/fastener-information/measuring/metric-thread-pitch.aspx
As shown, the pitch for the standard twelve mm metric thread is 1.75 mm. This is the thread size used on the "dry end" of the Tormek shaft. (The shafts of the T8 and T4 have the same diameters and thread sizes.) It is the same thread that was used on the "wet end" of the pre EZYlock shafts.
Tormek wisely chose to use the metric fine pitch thread for the EZYlock. Using the six divisions of the microadjust nut, even mere math mortals like me can do the calculations in our heads. From a known point, raising the microadjust four numbers (divisions) using 1.5 mm for a full revolution is 1.0 mm. Calculating one sixth of 1.75 mm would needlessly complicate the equation.
Ken
Except for Tormek's SVH-320 Planer Blade Jig's thumb wheels, which use 10 divisions (0.1mm per division) for a full revolution being 1.0mm ...
Be Sharp,
Your point is well taken about the thread pitch with the SVH-320. I actually purchased an SVH-320 twelve years ago, planning to use it to sharpen my "lunch box" planer blades. I did not realize that these blades are designed to be disposable, and the jig has remained unused in the box. Thus, the pitch of the threads has never entered my memory.
A familiarity of screw threads and pitches is useful knowledge around the shop..
Ken
I only mention this because I almost bought the SVH-320 nuts, as .1mm divisions are a lot easier to work with then .25mm divisions. They won't work on the regular and extended support bars!