Thread: Robert Sorby Pro-Edge Sharpening System

Fair comments Ern, however I was not suggesting that you, or anyone else for that matter,
was benchmarking against perfection. Perfection is that goal we all wish to achieve.

My reference to matching tool brands with systems is a direct reference to this machine.
Sorby developed this machine to sharpen their tools.

Now the last 2 paragraphs of what I had to say were meant to illustrate just this point.

I believe that different flute shapes have an effect on the way a gouge should be sharpened, for
best effect.

I mentioned the Henry Taylor Bowl gouge vs the Sorby gouge When both are sharpened using
the same technique the results are very different. I put this down to the flute shape, as do
other tuners with many years more experience than I.

The particular turner I mentioned will not own Sorby tools on account of this. Other turners
use the Sorby tools very successfully when they are sharpened in the Sorby manner.

I think there is a general technique for sharpening Bowl gouges that works satisfactorily
for most, if not all, brands. stray from this if you are not experienced and expert and you
and you may well be in trouble. I, for instance would not attempt to sharpen a bowl gouge
the way Neil Scobie does, or my friend does the Henry Taylor gouge.

I have see Richard Raffan's gouges ( once) up close. I shuddered at the number of facets, but
he manages to make the tool do the work he wants for him.

Perhaps it is a case of turning Technique and NOT sharpening technique that counts??

I believe the Pro Edge is probably a very good tool - if you want to have, and are satisfied with
the result it gives.

Arthur, Sorby don't have a monopoly on using a linisher for tool making and metal finishing. It's widely used for these purposes.

The only diff. between this and an 8" grind wheel that seems to be the most common sharpening device here is that this produces a flat grind. Flat vs. hollow was canvassed thoroughly in a recent thread.

In practice I had no trouble grinding the two HT tools or tool types that I use the most. After doing the Superflute I cut a few coves in that spindle piece and found nothing of concern.

Think you need to read my post again Ern!
Cheers,artme

Have done but we've gone off topic with flute shapes.

PM me your email address and I'll give you my view of the effect of that variable, or start a new thread?

New thread sounds fine!! Be my guest.

It's not an issue of concern for me but will say that flute shape is not the same as cutting edge shape but it has an influence on it.

With the new platen from Jim (nice service mate**) I took a hollow ground HT 1/2" skew to the Sorby. The bevel was 1 cm long. Included bevel angle 45º.


The skewing angle was very close to that of the Sorby guide.


It took about 5 mins to correct the angle and grind out the hollow using the Ceramic #120. Then another few minutes to refine the edge on an AlOx #240. The bevel finish was close to mirror.


There was a bit of dubbing over again, confirmed with a 20x loupe.


I did a bit of hand-powered end-grain paring of radiata just out of interest and the edge was adequate.


Then took it to planing a Radiata spindle piece.


The first pass of about 40mm produced air. 2nd produced dust. 3rd produced long fine shavings, longer than this tool has produced with a hollow ground bevel with the edge honed with an extra fine diamond paddle. One long shaving picked out from a pinch of them measured 70mm*.


Very good result.


Some other observations ...


With this setup it worked better to pass the bevel across the belt with the skew heel leading.


Dubbing over appears to reduce with a finishing effort centred on the belt width and a light touch.


Just to check swapped belt alignments, I've set tracking up to align the belt with the platen's right side. Just as well as the left or mount side drops off a bit.


It remains clear that the join section is doing most of the work when the belts are new. I'm tempted to take a small angle grinder to that high point.


Improvements I'd like to see:


1. Quick fixing for the side cover.
2. A vacuum port.
3. Fixing holes/countersinks, in partic. the lower one on the std platform, have burrs. But it's only a matter of seconds with W&D & sanding block to take them off.
4. Tighter tolerances on the gouge block track. I'm not finding accumulated grindings a problem.
5. If the platen is sacrificial and can be lapped, some adjustment in its mount to compensate. This is me just being anal as the yanks say . We're only talking about a few thou.


...


* Maybe this goes to the pref. of some experienced turners for a flat bevel.


** We didn't coordinate too well on this; Sorby's also sent one out which I'll forward to you.

Ern a concern with a vacuum port would be collecting metal filings, unsure if there is a vac suitable for this use.

Hang onto the platen.

Good point Jim.

The only sparks I'm seeing are off the ceramics; I've been sucking up grindings at the end of a session with a cheap shop vac. Yeah, maybe it'll die next week. Thanks; and thanks.

Had a shot at lapping the scored platen. 20 mins on float glass using quality #90 SiC grains. It's pretty hard steel. That effort improved it but it's not 'anal' flat. Actually it wasn't dead flat from the factory (excluding the left side from that observation).

...

I stepped up to a HT 1.25" skew. The skew angle was well out of the guide setting and I had at it with the #60 ceramic and 5 mins in, when it was working OK but not spectacularly (there was a lot of steel to remove) just out of interest I took it to the 8" bench grinder. That has a Norton #46 3X. Performed as expected: ripped off the steel but ran cool (almost continual grinding was possible but note this tool is its own heat sink) and was slow to clog.

Tomorrow I'll grind the bevel flat and refine the edge on the Sorby.

Took an old 60 mm wide Stanley plane blade to the unit, looking to regrind the bevel angle to 25º.

The Ceramic #120, now somewhat worn, did the job.

You don't need a dead straight edge as many woodies would after bevel reshaping take the blade to a whetstone with a jig for a secondary bevel.

With a unit with this capacity for getting a mirror finish there may be a lost opportunity here though, as the guide wasn't quite up to getting a straight edge with this size blade - in my view the reason for that is the mitred corners on the bottom of the platform meant that less support for the guide was available at the extreme points of the grinding needed.

I can't see the reason for which those corners are mitred, other than an aesthetic one.

I'm told that the A30, said by Sorby to be equiv. to P600, is actually equiv. to P800 acc to the 3M dogalogue.

So in the Sorby belt range there's a bit of a gap btwn #240 and #800.

That said, the Sorby Alox #240, as noted, produces a very good finish. Just stock up on them as on M2 they don't have a long life.

Originally Posted by rsser

So in the Sorby belt range there's a bit of a gap btwn #240 and #800.

Useful to remember that the US and European grit sizes (the P ones) start to diverge quite significantly when you get up around #600 to #800.

e.g #600 in the US system is 15 microns, yet 16 microns in the European system is P1200. See here.

That may (or may not) account for the apparent gap.

Thanks for the heads-up Neil.

And Trizact can use three different abrasive grains as well!

RS Woodworker's Square Guide