Different sized wheels...

[JustADudeInSweden]

Hey!

I have the regular wheel, it's getting a slight wobble so I have bought the tt50 to tru it.

Once I tru it (SG stone), the diameter will decrease ever so slightly, so my question is:

(The idea is to normal grind on SG stone, then finish on SJ.)

Will I have to set the angle again on a (new) Japn stone or will the tiny change in the stone diameter not matter enough to do so?

Thanks!

[micha]

In principle, you should make sure the stones have identical diameters, or you will have to set the angle again.
Practically, a litlle difference won't matter that much, as long as the second stone is slightly smaller. However, if you change to a larger diameter, you won't reach the very apex, adding more pressure will worsen the effect, so a little compensation might be needed.
I'd strongly recommend using one of the calculators for that.

[cbwx34]

Hey!

I have the regular wheel, it's getting a slight wobble so I have bought the tt50 to tru it.

Once I tru it (SG stone), the diameter will decrease ever so slightly, so my question is:

(The idea is to normal grind on SG stone, then finish on SJ.)

Will I have to set the angle again on a (new) Japn stone or will the tiny change in the stone diameter not matter enough to do so?

Thanks!

Wheel size affects the angle the least... it takes about 10mm of wheel size difference to equal a degree.  So, if the difference is not much, you probably won't need to reset anything.

Easiest way to check is remark the bevel with a Sharpie type marker, and make sure it's still hitting where you want it to.  You can make minute adjustments with the collar on the USB, if needed.

If you're into spreadsheets, forum member Gilles made the "Polishing Angle Calculator" to show the difference in wheel size, but in his case he was going from a 200 --> 250 wheel.

[RickKrung]

I have the SG, SB, SJ and a rock hard felt wheel in the mix, when I'm not using the CBN/diamond wheels.  All of the aforementioned wheels are different diameters, some quite a bit, such as the SG and SJ and the felt wheel is larger (254mm) than even the diamond wheels (250mm).  I've not paid much attention to cbwx34's point about how wheel diameter makes the least amount of difference, I think because I just use one of his calculators (GoCalc) to set the USB height (what has been called here - set the angle again) for each wheel AND I use the sharpie marker with every edge for every wheel change.  Putting on my broken record hat again, I think this is easy, largely because I use the distance to the surface of the wheel/rubber band method, rather than distance to the machine case.  I am quite happy with all of this as I've found there are few instances where I need to alter the height from the settings produced from GoCal as I move from one wheel to the other, which is verified by studying the scratch marks in the sharpie.   

I recommend you give some of the calculators a try long enough to get past the learning curves and just accept that changes in USB height are a given part of the process. 

Rick

[cbwx34]

I have the SG, SB, SJ and a rock hard felt wheel in the mix, when I'm not using the CBN/diamond wheels.  All of the aforementioned wheels are different diameters, some quite a bit, such as the SG and SJ and the felt wheel is larger (254mm) than even the diamond wheels (250mm).  I've not paid much attention to cbwx34's point about how wheel diameter makes the least amount of difference, I think because I just use one of his calculators (GoCalc) to set the USB height (what has been called here - set the angle again) for each wheel AND I use the sharpie marker with every edge for every wheel change.  Putting on my broken record hat again, I think this is easy, largely because I use the distance to the surface of the wheel/rubber band method, rather than distance to the machine case.  I am quite happy with all of this as I've found there are few instances where I need to alter the height from the settings produced from GoCal as I move from one wheel to the other, which is verified by studying the scratch marks in the sharpie.   

I recommend you give some of the calculators a try long enough to get past the learning curves and just accept that changes in USB height are a given part of the process. 

Rick

Nothing wrong with this, probably just not necessary.

I think the key here is, "tiny change" in stone diameter.  While I know that in the past, some people (myself included) got caught up in "decimal point changes", it's for the most part, not needed, and if the change isn't much, you can get away with no adjustment.  (Again, the marker is your friend here).

It takes nearly 3mm of stone diameter to equal a 1mm change in USB height.  So even if you need a small change at some point, I'd just use the markings on the USB microadjust... and come up with a quick reset method... for example 2 "clicks" when I switch from the SG to SJ stone, vs. making the exact change with a calculator.  (And you know, I'm a calculator fan!)

But use what works for you!

[JustADudeInSweden]

Lots of good replies and tips, thanks!

Concensious seems to be: up to 5mm is cool but use the marker to be sure.


Feel free to correct me or leave more tips!

Cheers!