Diamond wheel width inconsistencies?

[Ken S]

I agree that the computer is capable of much more precision than all measuring tools in all applications, even the finest tool and die tools. However, if your measurement slips by several millimeters, you have either a Tormek in serious need of repair or a problem with your technique. I highly recommend you contact support. (support@tormek.se)

Ken

[cbwx34]

Yes, the precision of this system is somewhat illusory.  You can carefully measure your USB-to-stone/base height to a fraction of a millimeter, but then, when you tighten down the USB screws, the height will change by several millimeters, even if you push down hard on the USB when tightening.

I agree that the computer is capable of much more precision than all measuring tools in all applications, even the finest tool and die tools. However, if your measurement slips by several millimeters, you have either a Tormek in serious need of repair or a problem with your technique. I highly recommend you contact support. (support@tormek.se)

Ken

Actually, I'd label this at least partially true.  If you take the stock USB and set it at what I would call near "maximum height", you reach a point where you can lock everything down and still get at least a couple of mm of play.  One of the reasons the "430" has longer legs.

But I just tested, and I don't see where you get several mm of change just by tightening the sleeve screws?   

[Kavik]

...
... software to measure absolute angles and settings down to fractions of mm and degrees...
...

I've said for some time now (as have others), this degree of accuracy ain't happenin'. 

Carry on....      

So.....we should all be saving ourselves hundreds of dollars by skipping all these inaccurate jigs and just freehand grind everything? 

I'm being a bit hyperbolic, of course.  As I was in the previous post too.
I don't care if I can't dial this in to 18.0 vs 18.25 degrees.
What I care about at this point is the last sentence in my previous post...if I can't hit the same spot every time I place the jig against the rest and touch the wheel, then this multi-base isn't worth the cost, or the frustration.


This morning I kind of got it working, but not in a way that I'm happy about.
Again, this is a skew chisel in the SVS50.  Set up meticulously in the jig, checked for any twist by using a ruler to ensure equal distance from edge of jig to tool on both ends of each side.
I reduced the protrusion of the chisel and the height of the USB to as low as i could go without the screws hitting the grinding wheel, and i turned the USB around so that I'm staying over the 2 legs of the bar (which will work for this jig, but not for others)
This gave me the absolute tightest setup i could muster, with the least amount of flex (though, there still is some at the angle locking joint on the multi-base)
I then locked the bar in place by turning the screw over the threaded leg till just snug, then tightened the screw over the smooth leg, then finished tightening the one on the threaded leg.  This is how I always do it, and it works fine every time when mounting the USB directly to the machine.
But, once locked down in the multi-base like this, the bar is not quite parallel to the side of the wheel.  Through trial and error, I had to intentionally twist the USB while tightening it down, in order to make it parallel.

I believe the problem to be in the locking pivot joint of the multi-base.
Even if I crank that thing down to an uncomfortable level of tightness, there is still a lot of flex right at that joint, and it isn't creating a perfectly parallel surface even without any pressure applied.
I even dismantled the pivot to ensure there wasn't anything in there causing a bad seating, and everything looked fine.
I don't believe a ~1" diameter locking ring with a single bolt is good enough to hold this as securely as it should.


Again, it's not about accuracy of the chosen bevel angle, it's about consistency.  And i don't think i'm being overly critical when the amount of play I'm seeing here can literally keep me from reaching the apex across the entire length of the blade (which is only a little over an inch long).  After all, isn't the whole idea behind using jigs that you can repeatedly get quick touchups without a) having to grind an entire new bevel each time, or b) spending 20 minutes fiddling with, and forcing things into place to find the lucky spot where you got it to line up once before?

[cbwx34]

...
I believe the problem to be in the locking pivot joint of the multi-base.
Even if I crank that thing down to an uncomfortable level of tightness, there is still a lot of flex right at that joint, and it isn't creating a perfectly parallel surface even without any pressure applied.
I even dismantled the pivot to ensure there wasn't anything in there causing a bad seating, and everything looked fine.
I don't believe a ~1" diameter locking ring with a single bolt is good enough to hold this as securely as it should.
...

I'm wondering if your MB-100 is defective?  I just dug mine out, (admittedly, don't use it much) and the pivot joint on mine locks solid.  I don't have any detectable play.

Maybe post a short video of what you're seeing?

[3D Anvil]

Actually, I'd label this at least partially true.  If you take the stock USB and set it at what I would call near "maximum height", you reach a point where you can lock everything down and still get at least a couple of mm of play.  One of the reasons the "430" has longer legs.

But I just tested, and I don't see where you get several mm of change just by tightening the sleeve screws?   

Yeah, that was an exaggeration.  Sorry about that!  I just measured my machine.  At 15 dps with 139mm projection, I have to dial the micro-adjuster +2.4 in order to correct for the shift from the set screws, which I believe equates to 0.6mm.  In this case, that results in a difference of 0.4° in sharpening angle, which isn't huge, but it's significant if you're trying to be very precise.

OTOH, now that I've figured this out (thank you  ), I just have to measure my stone distance and then dial in +2.4 stops and I should be good to go.

[Kavik]

...
I believe the problem to be in the locking pivot joint of the multi-base.
Even if I crank that thing down to an uncomfortable level of tightness, there is still a lot of flex right at that joint, and it isn't creating a perfectly parallel surface even without any pressure applied.
I even dismantled the pivot to ensure there wasn't anything in there causing a bad seating, and everything looked fine.
I don't believe a ~1" diameter locking ring with a single bolt is good enough to hold this as securely as it should.
...

I'm wondering if your MB-100 is defective?  I just dug mine out, (admittedly, don't use it much) and the pivot joint on mine locks solid.  I don't have any detectable play.

Maybe post a short video of what you're seeing?

Won't be home this evening, but I'll see if I can capture it on video tomorrow.

To elaborate, i wouldn't call it play in the mechanism. Once it's locked down, there isn't any slop in the interlocking ridges, no rattling rotational movement. It's just....bendy.

Mounted to the machine, puting any light to medium pressure on the USB, i can see a small amount of flex through the whole unit, mostly at that pivot joint,i think