I just received an answer to my request for diamond wheel runout tolerances from support. Here is the report:
"The tolerances we aiming for on the diamond wheels is Radial and Axial deviation of 0,15mm on the 250 wheels.
The 200 mm for the T-2 have larger tolerances of Radial 0,20mm and Axial 0,30mm."
The radial (edge) tolerance is tighter than the original spec for the SG (0.15mm instead of + or - 0.2mm. I am not sure if the new spec, 0.15mm is total or plus or minus. Either way is is tighter.) The axisl tolerance is also 0.15mm, much tighter than the old + or - 0.5mm. I would expect this higher precision, since the side of the wheel is now bring used as a grinding surface and cannot be trued.
This is essential information. Thanks, support!
Ken
That is interesting information Ken, thanks for getting it.
It might be that the superior tolerances come from the greater precision that can be achieved in machining steel vs. stone. With that said, I would not be bothered much by minor runout on the flat face because at the low speed of the Tormeks it should only result in some gentle movement of the blade/tool.
I think that flatness is another specification that would be relevant in some applications for these wheels. (Diamond plates will often advertise flatness in the .025mm-.05mm range.)
Gord
I agree in regard to flatness. I have not measured anything, but I did notice a distinct LACK of flatness when I was sharpening drill bits. I believe I mentioned this previously. I'm not sure how much it matter, but I definitely expected them to be much flatter, perhaps even totally flat. I know that our perceptions can often detect minute differences that can be difficult to measure, such as the finger detecting a difference in surface roughness of an object that may be discernible visually but cannot or is very difficult to measure. I should try measuring how much lower the center of the diamond wheels are to give perspective.
It may be passed of as variance in the diamond coating, but that is not very comforting either.
Perhaps their tolerance for flatness should also be requested.
Rick
I think we will have to wait until we, which includes Tormek itself, get more experience using these new wheels. I do not expect the Tormek to perform like a surface grinder; it was never designed that way. At this point, I don't think we know what a practical working tolerance range is. I am not even convinced we need the flat grinding capability, although I an open to learning about it.
Ken
Ken, I have the same questions you have about the utility of flat grinding on the Tormek, but it looks like there is a demand for this and the diamond wheels are Tormek's response. So I have thought about your questions in that context.
We know that we need flatness on the circumference of our stones, regardless of how good their radial and axial tolerances, and that is why we use the TT-50 truing tool. The diamond stones have the ability to keep their factory-made flatness indefinitely, so we don't need to true them, but this makes the initial flatness more critical. Ridges and bumps are there forever.
The same is true on the flat faces of the wheels. The reason we true our flat hand stones (and that good diamond plates come with impressive flatness specifications) is that flatness matters. It probably matters less on a rotating stone because you get the benefit of the inaccuracies cancelling each other out, but ridges and bumps would still be suboptimal, and potentially problematic.
So information on the flatness of the diamond wheels would be informative.
With this said, I would expect the flatness of the Tormek wheels to be good, because it seems like such a controllable variable (machined steel, even coatings).
As you say, we will have to get some experience with these stones, but as a potential purchaser who is waiting for the diamond wheels to come back into supply, I am interested in observations like Rick's, which redouble my interest in Tormek's target specification and as-built results for flatness.
Gord
Gord,
I have some flat ground turning tools to sharpen. That will give me a good chance for a real life test of the side grit and MB-100. As I said, I am not yet convinced, but am keeping an open mind. I will post my observations, whatever they are.
Like you, I expect high quality from Tormek.
Ken
In the discussion above, Ken noted the runout tolerances for the diamond wheels, and then the discussion moved to the similar importance of the flatness tolerances.
So, I asked Tormek Support what the flatness tolerances were. The initial response I got had to do with the evenness of the diamond surface covering (the spec provided by Support was "0,10 mm after initial break in".)
OK, good to know, but not what I was looking for. I followed-up and specifically requested the machined flatness of the wheel--this to me is a critical specification. As discussed above, if the machined surface has ridges or bumps, it doesn't matter how even the layer of diamonds is.
The response from Tormek Support was that this specification was confidential. Huh? I questioned Support about this, noting that diamond plate manufacturers all give this spec because it is important. So, I asked for the spec, but it has been over three weeks and I have not heard from Support.
As I have said, these wheels are doubtless produced on a lathe or some other milling machine and the flatness from that process can be good, so I am not expecting a problem here. But I am disappointed in Tormek Support's response. It is nonsense to me that a performance specification would be confidential. (I also wish they would answer their emails, this is the second time I have contacted Support and the second time I have been left waiting indefinitely for an answer.)
Gord
Quote from: GKC on February 07, 2019, 02:31:16 PM
...
But I am disappointed in Tormek Support's response. It is nonsense to me that a performance specification would be confidential. (I also wish they would answer their emails, this is the second time I have contacted Support and the second time I have been left waiting indefinitely for an answer.)
Gord
Join the crowd... I have had the similar "no response" when I was seeking info to help with the USB Position Calculator stuff. I really think Tormek doesn't know that sharpeners have become more "technical" in their desire to learn... and I think it will eventually cost them in the long run. :-\