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The parts diagram clearly shows T7s should have the spring. All four of my T7s have holes for the spring. I am more curious about how many owners have T7s without springs, are using them, and possibly haven't noticed any difference.

I have four used Tormek T-7s, but only one has the "distance spring for the motor" (part number 61). I'm asking T-7 owners whether their machines have the spring, or no spring?

Thanks.

Little to no pressure.

From experience, BESS readings increasing tells me I have to re-spray the 1micron diamond onto the felt wheel.

You might want to try Tormek's new CW-220 composite deburring wheel. I reported my extremely positive expereience with it a couple of months ago. 

Rick, the accuracy analysis using drill bits in 1/64" increments was to see if such increments were fine enough for my needs (de-rooting the wire edge) while NOT spending a lot of money. I'm guessing most members, like I, already have a set of drill bits and feeler gauges. I don't want to buy a set of gauge blocks if I don't have to. The conclusion is that, for my needs, I don't. Therefore, pin gages are really unnecessary too. It's good enough. Hopefully other members will conclude that it's good enough for them too.

The whole accuracy thing is not to make sure the angle is exactly 15 degrees versus 15.05 degrees, but to ensure that the edge doesn't get rounded off as it progresses through all the machines. My "rig" is designed for speed. For example, when sharpening Shuns, it goes through 3 grinding wheels on two T7s, 3 paper wheels on two different buffers, and a leather wheel on another T7 with a FVB. Therefore, I need to ensure the sharpening angle is consistent with all the machines. 

As for the degree of "fiddly-ness", that's the whole point. The blocks do not topple (on end they're still 25mm x 50mm).They barely fit between the wheel and the leg sleeves. This is where the T7 is better than a T8. Again, I find this method to be MUCH less fiddly than using calipers. (And larger drill bits are actually easier to work with than small ones!)

Perhaps later I will get some precisely machined custom blocks. But I'm happy with the way it is for now - again, because it's NOT fiddly. (Mitutoyo does make custom length gauge blocks...)

Finally, yes, all the above is based on the assumption that the machine top is parallel with the stone surface. I'm not going to try to address that : )

please excuse me if i start smiling at your comments. if you are already so meticulous about the whole thing..... maybe you can also tell me the difference in the degree of pain when i cut myself with an exactly 15° ground knife compared to a cut with a 15.05° ground knife? i'm sure you understand what i'm getting at..... you can also exaggerate everything. simple and comprehensible should be the motto. under this aspect, your explanations go absolutely too far for me.
but you have put a lot of thought into it, respect for that.
greetings Hanns

Hanns, I'm not sure if I understand your question. But then, your English is still way better than my German : )

CONCLUSION

This is an alternative, low-cost way to set computerized USB height. I find it is accurate enough for my needs - ensuring the pesky wire edge has been de-rooted (my sharpening business's main selling point is long edge life). However, if one is chasing ultimate "bragging rights" sharpness, then one should invest in a 102 piece gauge block set, or go back to the caliper method.

USB NOT PARALLEL TO TORMEK TOP

Tormek recommends setting the USB by pressing directly over the threaded leg while tightening the locking screw. Only after that should the other locking screw be tightened. However, some of my Tormek USB have legs that are not square with the top bar. With such USB, the Tormek method does not result in a USB parallel with the Tormek casing top.

Tormek USBs fit tightly into Tormek sleeves. Some aftermarket bars measure smaller - around 11.8 mm instead of 12mm. This means more play (One measured 1.18mm height difference between the two legs that are 90mm apart). This extrapolates to 3.74mm error at that bar's long end.   

The solution: set up using TWO sets of gauge blocks - one set close to the left edge of the Tormek's top, and the other set close to the right edge. Push down on BOTH legs at the same time, then tighten both locking screws (loosen the micro adjust nut(s) first, then snug them down afterwards). This works best on older Tormeks up to T7. The T8 has sloped left and right sides, so you cannot place gauge blocks there. The T8's on/off switch also blocks placing gauge blocks between the two cast leg sleeves.

LABELS

I also made magnetic labels marked with the spacers needed. I can now glance at a machine and immediately see what it is set for. If I need to change the angle I switch labels and adjust the USB height per that label's instructions. No software calculations.

REAL LIFE RESULTS

The first picture shows setting up a T7's USB height. Software says 168.89mm to top of USB, so target inside measurement is 168.89mm - 12.00mm = 156.89mm.

The 156.89mm is set with two metric 25-50-75 setup blocks plus a 17/64" drill bit (75mm + 75mm + 6.746mm = 156.75mm). With this spacer combo, it's .14mm too low.

You would think using such drill bits means duller edges. But my experience yields sharper edges. Before, my BESS readings seem to be around 100 (at 15 degrees). Now they seem to be around 80.

I can comfortably say I am not having higher BESS readings using this inside spacer method using 1/64" increment drill bits. In addition, it is faster to setup and much easier to repeat.

METRIC GAUGE BLOCKS

Machinists are familiar with 1-2-3 gauge (setup) blocks - they are precisely machined and ground to have 1" x 2" x 3" sides. Since my software is metric, I bought 25mm-50mm-75mm gauge blocks.

For the last bit of space, I use feeler gauges (0-1.0mm) or, when greater than 1mm, drill bits.

But are 1/64" drill bit increments small enough?

Some of the Australian sharpener's protocols (i.e. for Shun) varies the angle by only .1 degree. His software calculates that to be about .15mm USB height variance (about .00590"). 1/64" = .015625" = about .4mm. So, 1/64" difference translates to .27 degrees difference - too coarse to vary the angle by .1 degree. In other words, using 1/64" incremental drill bits yields .27 degree sharpening angle accuracy. (Metric drill bits go up in .5mm increments = .33 degrees).

Despite this, I found using gauge blocks plus 1/64" increment drill bits seems to yield lower BESS values!

SPACERS

Spacer sets, commonly known as gauge block sets, are highly accurate metal blocks that can be stacked together to form your desired spacer. There is virtually zero cumulative error from stacking gauge blocks with flat machined surfaces due to "wringing". (For a fascinating history on gauge blocks, search Mitutoyo's web site for the PDF, "History of The Gage Block" under Literature > Corporate. "Wringing" is explained on page 5).

However, two budget-friendly 102 piece gauge block sets would still cost around $300. So I went for a cheaper solution, comprising of 1-2-3 gauge blocks ($30), a 10mm gauge block ($20), a 1/16" to 1/2" drill bit set in 1/64" increments (already have), and a set of metric feeler gauges (already have). Total outlay: $50. (I have two sets, so my outlay was $100.)

USE INSIDE MEASUREMENT INSTEAD?

I use Australian software. All three (Grinding, Frontal Vertical Base, and Paper Wheel) calculate the USB height to the USB's top.

But what if we measure instead to the USB's bottom? Then we are dealing with an inside measurement.

USB diameter is 12mm. So, all we have to do is subtract 12mm to get the corresponding inside measurement. Simply fill the desired space with the correct spacers (conveniently held down by gravity), and you're done. In contrast to using calipers, the strengths are:

1) Could be more accurate (more on this below)
2) Much less parallax error
3) Faster
4) Easily repeatable
5) Using TWO sets of spacers can help setup a USB parallel to a Tormek's top surface. 

SUMMARY: A $50 investment could be a faster, more repeatable way to set Tormek Universal Support Bar ("USB") height. It may not result in "bragging rights" BESS numbers, but I consistently get BESS numbers below 100. 

BACKGROUND

Computer software has taken Tormeks into the 21st Century. I use calipers to set the USB height. However, I was not happy because:

1) Regular calipers are poor depth calipers. The caliper end is barely wide enough to go over the 12mm diameter USB. That is why both my calipers have depth gauge adapters on the ends. However, even after setting them up using a flat reference surface, I found one caliper measuring .1mm short and the other measuring .1mm long.
2) Parallax error. Unless the extended leg is absolutely vertical, the measurement will be too long.
3) Speed - moving the caliper to the desired measurement takes time. My iGaging calipers have what they call "Absolute Origin" - they remember where they are even after shutting off. This helps, but I wanted better.
4) Poor repeatability due to the above three things.
5) Longer USB means larger errors the farther one is away from the two vertical legs. Tormek's new US-430 is 34% longer than the US-105.
Some after-market USB legs are smaller (11.83 mm diameter vs. 12 mm diameter).  Such bars could result in not being parallel with the Tormek's top surface due to play inside the 12mm diameter Tormek leg sleeves.

This 2-minute video, "Science Behind the Mirror Edge", might be helpful:

https://m.youtube.com/watch?v=DzsV3T-Isi4

It's M6 x 1.0mm, the most common M6 size and thread pitch ("standard pitch"). The lesser common one is M6 x .75mm ("fine pitch").