Thread: Robert Sorby Pro-Edge Sharpening System

Originally Posted by rsser

RH, if you read the post you would've seen I was referring to a few sticky deposits on the platen and rollers, not on the belts.

Perhaps RH was referring to my comments on diamond belts, their cost and my concern that the bonding may not hold the diamond long enough to get your value from them (when grinding steel). I have no experience of them, but agree with RH that all of that flexing around a tight radius twice every rev may weaken the bond and let the diamond go well before it has stopped cutting.

Point taken that your interest is in sharpening systems, not abrasives, Ern.

But for me, having now used both diamond and CBN abrasives for sharpening my turning tools, I'm unlikely to adopt a 'sharpening system' that doesn't have those premium abrasives as economical options. In an earlier post in this thread you said "It's all a matter of what trade-offs you can live with of course."

I've always been interested in the idea of belt grinders for sharpening, having used them for rehabbing knives, but I'm not sure I'm prepared to trade-off the benefits of the above premium abrasives for sharpening turning tool, well not without a lot of convincing.

However, I'm following your thread with interest, Ern.

Brent Beach, who is worth listening to on many matters to do with sharpening, provide arguments in support of belt grinders for tool sharpening on his Belt Grinder page.

The one aspect of belt grinding that hasn't had a lot of discussion are the pros and cons of flat bevels for woodturning. With the increasing use of belt grinders for sharpening we might get more on that. I have started a separate thread on Flat Grind Versus Hollow Grind so as not to hijack this thread.

Apologies to RH if mine was the misreading.

Yes, Brent's material is interesting and I'd read that part recently when staring at the 1" Ryobi belt sander wondering whether it was worth the effort of improving the platform and rigging up a jig mount. Decided not to as a 2" width is a big advantage over 1".

Mike Darlow has also been an advocate of belt sharpening and one his books pictures an attachment available for a bench grinder (Multi-tool or somesuch IIRC).

In terms of the finish on the bevel and therefore the edge, it will be interesting to see how a tool performs with the Trizact 3000 treatment.

Meantime the M2 plane blade has arrived for cleaning up of the back. Darnit, there wasn't one Stanley blade in the shed that hadn't had a makeover that could be used in a test. Must be an OCD.

Look forward to the thread on flat v hollow grinds. (Gotta love Brent's maths on wheels and bevel angle variation!).

Episode XII:

Took the detail gouge to #600 (equiv.) Trizact in the V-block.

This is still ripping the metal off and tip dubbing over re-occurred. Pulled back, took more time, got most of it out. Will cut with it and see. Polished bevel. Better than the flute finish (more honing needed there).

Episode XIII

mic-d's plane blade. 50mm wide. One of Helmut's specials. Quality M2 steel. By eyeball I couldn't see what Michael's concern was. But with a 20x loupe, oh yeah. The surface grinding was irregular. Mostly good but some deep scratches were left.

To sidestep a moment: our flatware colleagues have long known that to get a clean cut and keep a long-lasting edge, the finer the bevel and back treatment the better it is. And now there's also plenty of evidence for turning tools, not least from Neil, that the same applies to us.

With the back of a plane blade, you have to flatten and then work to a polished finish. And then do the bevel to the same standard. It's pointless refining one intersecting face and ignoring the other.

To the point (cough): I wasn't going to trash Michael's fine blade with experimenting. As it happens, I have one of Helmut's specials of the same width. From the 'factory' I found this took nice cuts but I'm no plane expert. This was the trial blade for back flattening and polishing.

1. Ceramic #60: wowsers! Talk about rip off metal! Ideal for flattening.
2. AlOx #120: slower going. #60 scratches came out easily enough.
3. Michael's blade on the same belt: same deal. But polishing was happening and it shouldn't at this grit. IMO the belt is now worn. Wish I had a Ceramic #120.
4. AlOx #240: did better but it's a near new belt.
5. Trizact #600: polishing happening. A few scratches left 5mm beyond the edge. Will take it to #1000 on the WorkSharp disc.

Upshot 1: Michael's blade has stayed flat cross-wise and was ground clean and polished to 5mm up from the edge. Belts are wearing out. With a full kit of belts I would've started with full guns blazing running up through the grits.

2: Now that I know what the Pro-Edge is capable of I'd order next time a full kit of the ceramic and Trizact belts.

The perennial worry with lapping is convexity due to differential exposure to abrasive effect. Across the blade on these two there was a good result. Bravo Mr Sorby! Along the blade there's a bit of drop off at the tip end. Wouldn't be a prob. with a std Stanley setup; could be with replacement blades & chipbreakers.

No apology necessary. I have noticed bumps with every sanding belt I have used, but have never used a belt sharpening system. For sharpening, I would consider a grinder and wheels to be more for turning tools, and maybe lawn mower blades, but not for fine sharpening like plane soles and blades, or kitchen knives. This would, for me mean having one set up for my turning tools, and one for other fine edge tools. Kind of like chucks, you may start out with one, but generally end up with several, so you don't have to change out jaws every time you want to do some thing different.

I did talk to Stuart a week or so ago about his Omni Grinder, and he is looking to get on order maybe 1,000 of them so he can afford to buy all the tools necessary to make them in house rather than farm it out. I do want one, and consider it a huge step up from the Sorby Pro-Edge. He expects it to sell better in the metal industry world than just for woodturners.

robo hippy

Episode XIII:

Had a play working the edge of a Mundial 8" French cook's knife on the Trizact #600 (equiv.). Inked the bevels; a couple of freehand passes each side took off a deal of metal as you'd expect as this grit. I started with the edge leading and this produced some abrasive dust so then changed to edge trailing. The edge is adequate for my partner's uses. The 1200 and 3000 grits when they arrive should produce a better than adequate result.

I'm keen to continue to use my ProEdge but there's been a delay in belt shipments from the UK.

Sorby offer a good range of belts for various applications. Big plus.

So at this stage of ownership I see three downsides:

1. Platen scoring with #60 belt.
2. Belt join leading to edge dubbing over. Controllable but sub-optimal.
3. Belt availability.

Re 3. it's early days in the introduction of the unit to the Aus market.

Jim from Carrolls WoodCraft, the supplier of the machine, is on the ball and doing the best he can to ensure a supply of belts and to consult with Sorby on 1. and 2.

And that's why I prefer to buy locally.

i have been watching this thread very carefully and i think...............
santa is bring me one this year

i must have been a good boy this year
can't wait for xmas
cheers smiife

Hope Santa has been working out coz he's getting one for me to

Hope Santa's back is up to it! The Deluxe version weighs 18kg packed. Says something about how solid it is.

I should say re knife sharpening freehand that on this unit it can't be done the way it's shown in Lee's book on sharpening. Ie. loose belt, edge leading. The arm that holds the rollers is in the way. Looking at the pic in that book it appears that the abrasive would prob. connect with the whole blade as well and that would take out any maker's mark or gunmetal finish and that doesn't appeal. I may be wrong though.

Carroll's should have new belts in soon now and I'm looking forward to getting down to more tin tacks.

It's tempting to have a go at DIY belts. A std size is 50 x 915 mm. The joining tape on the Sorby's is blue glass-reinforced. Best estimate is that it's 0.1 - 0.2 mm thick. Can't find a source on the web. White/silver is out there and one sample measured 0.1 mm.

Jim's sent out new belts so I can wind the tongue back into the mouth

Have done some more playing.

Took the knife mentioned above to the #1200 (equiv.) and #3000 Trizacts. It was possible with these to present a leading edge. Couple of passes on each on both bevels and the knife cuts paper.

There's still the design limitation imposed by having the roller mount arm almost flush with the abrasive surface which means the choil (hilt, whatever you call it) restricts how far you can come in from the left hand side ... but it's not a deal breaker.

Of more concern is this: I went to refresh the Beading and Parting tool edge, starting where I left off at #600 (equiv.) Trizact and again got the slight dubbing over mentioned earlier. Am now convinced this is a product of the raised join section. It can be dealt with by using a light touch but the join section is doing all the work and it slows things down. Maybe in time as the join section wears down things will speed up. And given the geometry of cutting in practice slight dubbing over may mean little - have yet to test whether this in-principle deficit means anything in practice.

I've also found using the gouge block side to guide the B&P tool that there was some slop in the mating of the guide and the platform groove. Of course there has to be some clearance but it looks to me to be excessive. It measured 10 thou. (The skew guide by contrast measures 7 thou.) It's possible of course by using consistent pressure to get a consistent result but the greater the projection of the tool from the platform the more skill is required.

Robohippy, after this experience, I'd say this system works for turners as well as knife sharpeners and handplane and bench chisel users and rehabbers. I can't think of any other device that is as versatile, and I've used a few. And as you'd expect, there are compromises.

But to paraphrase someone, it's only sharpening.

Sorby has sent a detailed reply to my questions dealing with the issues above.

1. The platen shouldn't have scored so quickly and they'll send a replacement. It was not my heavy handedness. That said it is a sacrificial part of the machine. It apparently can be lapped.

2. The dubbing over of the B&P tool edge could be a result of the belt not lying flat on the platen. I checked this; there was a little buldging out in the middle and the right edge was a little above the platen. They advised rotating the belt tracking bolt through 180 degrees - and this pulled the belt flatter.

3. They don't think a turning tool needs to be sharpened above #240. I've pointed them in the direction of Lacer and Wright's tests as published in American Woodturner.

4. The gouge guide block track is deliberately slack to allow for grindings to clear. The plane blade guide is tighter since edge squareness is important there. I guess the B&P tool is the only turning tool I can think of on which edge squareness is important, in the case of cutting accurate tenons.

With belts running flatter, it's obvious that the gouge guide is far from optimal in getting a square straight cutting edge. To be fair it wasn't designed for it and a plane blade/bench chisel guide is on it's way from Jim Carroll. Tolerances are said to be tighter.

(Post edited).

1. Further tests with a Sorby HSS 3/8th B&P tool ...

The belts are running flatter but dubbing over remains in some applications and I can't see a pattern yet. I'm a bit suss about the AlOx belts that said.

Have learned that it's possible to make the gouge guide work as a 'straight edge' tool guide by consistently pressuring the top left side. I'm now getting square and straight.

Re ripping off steel, the #60 Ceramic belt outperforms the #60 Zirconium belt by a country mile. Can't yet comment on belt life yet.

The AlOx belts are cheap and can't be expected to last long; the join on the #120 is doing nearly all the work but the #240 does better. Go figure. Using a rubber stick to clean the belts helps.

2. Trials with a couple of gouges on the gouge guide (just to be novel ).

First was with a HT 3/8" Superflute on a #120 Ceramic belt. Got a bit of dubbing over initially but lightened off and all was good. To preserve the grind shape that I like I pushed the bevel up the belt a bit to pull the wings back.

Also on that #120, a HT 1.5" forged spindle gouge. No concerns.

Both done at 45 degrees.

Both efforts raised a burr and left a bevel finish that was a good deal rougher than that from the #120 diamond wheel. Ceramics have the rep of being aggressive so that's to be expected. But with this unit it's quick to change grit to refine an edge.

In terms of speed and ease, trial #2 is saying good things to me. I like the positive angle lock of the platform and also like not having to fiddle with a clamped jig. For touch-ups #240 and #600 are quickly available.

...

I tested the minor dubbing over of the B&P tool on a 65mm diam. spindle piece and it made fine peeling cuts impossible. By minor I mean what I could see under a good light. Was under a mm and prob. under half a mm.

...

Many thanks to Jim Carroll and to Phil of Robert Sorby for their after-sale support.
.

All this Sharpening talk is having the opposite effect on senses!

Why can't we accept that there is never likely to be the state of perfection
achievable that we all aspire to?

We have many discussions on the issue, there have been countless articles in
journals over the years and there are any number of methods and systems either
on the market or advanced by their protagonists.

I won't give my personal opinions on all that has been said except o say that this
is just another imperfect system, the more so because it is designed for Sorby tools.

On this point I can say, from experience, that differing brands of tools behave
differently to the same sharpening technique.

A good turner friend of mine has his own method for sharpening Henry Taylor bowl
gouges. They cut beautifully when done his way. The same method used on Sorby
tools renders them virtually useless.

QED?