TormekCalc3 - Advanced grinding calculator

[SergeiDubovsky]

This one?

I have no idea how to figure out the tangent to a stone surface.

[cbwx34]

You measure the shortest distance between the top of the USB to the stone (basically, aim an imaginary line to the center of the wheel).

[SergeiDubovsky]

I will try that. The trouble I see with it - there is a subjective part in the measurement. That shortest distance is an estimation.

[cbwx34]

I will try that. The trouble I see with it - there is a subjective part in the measurement. That shortest distance is an estimation.

Pretty easy after a few tries.  Some have come up with a method to help while learning, for example RickKrung used a rubber band...



... all methods are a bit subjective, but more than enough in accuracy. 

[SergeiDubovsky]

<3 the rubber band jig. That's clever!

[jvh]

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

[tgbto]

With regard to digital height reading, I think I remember from my robotics days the IR detection cone being somewhat around 20° inclusive. Which means a 50mm measurement area at a 150mm distance, and I'm not sure the detection area will be clean enough... Maybe LIDAR ?

As for the USB to stone measurement being subjective, I find it to be quite precise even without the rubber band : you just have to rotate the calipers around the USB till you barely touch the stone, and you have the shortest distance. The tiniest rotation of the microadjust nut takes it off the wheel, which is about as precise as you can go on the Tormek.

But even when going digital, my gut feeling is this area is going to be cleaner than the one directly under the USB, and what you'll get as the closest object is indeed the stone at the point closest to USB.

[Ken S]

I like Rick's use of a marking gage as a "depth gage" to measure from the top of the support bar to the edge of the grinding wheel. (I call this measurement "Distance" in my PDF describing the kenjig.) The substantial metal rod seems less rickety than the thin flat metal extension on four way calipers. I prefer the larger footprint "gage block" approach of the kenjig, although the adjustability feature of the marking gage is formidable. (Rick, a machined rod with a larger foot would combine the best features of both. Or, perhaps a collar or spacer with an ID matching the diameter of the rod. This would eliminate the need for machining.)

I have always measured from the top of the support bar to the edge of the grinding wheel, as highlighted in yellow in the diagram. I have never thought of it was inaccurate. The flat bottom does not perfectly match the curvature of the grinding wheel; however, I can eyeball matching gaps on both sides. Given the same wheel diameter, it works on my T7 or T8 with no compensation. I have never understand any advantage for measuring to the frame.

Ken

[cbwx34]

...
The substantial metal rod seems less rickety than the thin flat metal extension on four way calipers.
...

I flipped it around...



... I found doing it this way to be more accurate/consistent, than trying to use the thin extension. 

[Perra]

I can also contribute with a tip on a jig that I use daily. Fast and easy to use. It works for all diameters of wheels that I have. Both grinding wheels and honing wheels. Easy to make yourself if you are a little handy. I have adjusted the slide gauge 0.15mm to compensate for the highest point of the wheel which is in between the legs of the "fork". A little training and then it's very quick to set or measure the USB height

[SergeiDubovsky]

That's a nice idea! More I look at this, more I want to figure out the 3D modeling/printing.

[RichColvin]

Sergei, if you go down this path, look hard at Fusion 360.  It is a great tool for 3D modeling, and I understand there is a licensing which is free for non-commercial users.  Some of the other 3D CAD programs I've tried don't make smooth curves and that can be problematic for some parts you would want to make.

Fusion 360 can output to a 3D printer directly, but I prefer to output the file in STL format, and then use a separate slicer tool.  I use Ultimaker's Cura for that.  It is a free tool.

As for 3D printers, the  Creality Ender is a good product at a good price.  There are other better and faster printers, but the Creality Ender seems to be a good starting printer (I have the Ender 3 v2).  You can print using both PLA and ABS filament which covers most use cases.

[SergeiDubovsky]

@RichColvin! Just a person I need right now. A quick question for you: The VF constant is slightly off in the TormekCalc. I believe it is set for Vadim's VFB. I measured the distance from the center of horizontal support arm to the top of the unit is 10.14mm

4.14mm from the hole edge to the top and 12mm diameter of the hole.
Is that correct? It was not the best measurement

In the Calc the constant VF for the Colvin Tools is set to 53.80 from my measurements is comes to 51.14mm
I need to re-measure everything to be sure.

Let's do a math check. I need this distance:


In the Calc we have a HH of 41.0 (F17) and VF 56.0 (F20) the difference is 15.0mm.
I measured that value for the Colvin Tools as 10.14mm, so the VF for the Machine should be 56.0 - (15-10.14) = 51.14mm

[RichColvin]

The bar should be 12mm in diameter, so the number you are seeking should be 12/2 + 4.14 = 10.14.

[WimSpi]

I slightly modified my depth gauge