Ellsworth shape grind on ProEdge?

[Chris152]

Is there a simple way to achieve the convex wings of Ellsworth's shape of bowl gouge using the jigs, or do you just have to 'wing it'?

Thanks
C

 

[Sideways]

Trying to solve the same question Chis. I have a new proedge and a new Crown Ellsworth 3/8 bowl gouge that I won't use until i've convinced myself I can maintain the factory grind.
I'm pretty much convinced from reading that you need the long grind widget with three holes for different fingernails - the Ellsworth I believe needs the furthest one.
I have measured the grind angle at the tip of my gouge and it's 58 degrees as it came from the factory. I've heard that the Ellsworth is "meant" to be 60, but it won't make any difference to me.
The two things left to figure are the protrusion (how far the tool stick through the jig, P on a tormek) that will give me a 58 degree grind with the #3 hole hole on the long grind jig, and if there's any need to alter the angle of the knuckle of the jig from it's default angle.

Interesting that the newest Sorby proedge has a new, simplified gouge jig that is slightly less adjustable than the original one they bought / licensed from tormek.

 

[Paul Hannaby]

I think the Tormek instructions suggest a 75mm protrusion for an Ellsworth grind and jig setting 6. The same numbers are used on the Sorby jig, which is made by Tormek.

I fiddle with the bar spacing setting to adjust the grind to a 50° - ish grind which I prefer for general use. 60° is good on the inside bottom of the bowl but a bit steep for my liking on the outside so I go for around 50° as an all rounder.

 

[Chris152]

The only variables on mine are the angle of the wings - which it'll cut straight when the gouge is inverted on the platform; the three holes on the extension widget which allows the bevel to be cut to length; and the elbow of the jig holding the gouge, which is set to 120 degrees (and I'm reluctant to shift that without knowing it'll work).
When I look at the Tormek guide the jig looks quite a different setup - a dial with numbers on (I guess that's what you're referring to, Paul?).
I can grind the angle of the wings and the bevel to extend the cutting edge, but can't get clear in my mind how the jig can be used to achieve the convex wings. The Sorby grinding guide (online) only shows straight wings.

 

[CHJ]

….. how the jig can be used to achieve the convex wings. The Sorby grinding guide (online) only shows straight wings.

Curvature is normally achieved by operator allowing the apprpriate dwell time while transitioning from side to side.
It is also influenced by the Flute profile of the gouge stock.

 

[Chris152]

That's great Chas - well, sort of, in that it clearly requires user skill which could be the beginning of the end of the gouge I'm going to try on.
Thanks all.
C

 

[Sideways]

Chris, you and I clearly have the same, new design of pro edge gouge jig. The one with the big red knob - yes ? I hadn't actually seen this until one arrived in the box. This is a derivative of the original tormek design. It is adjustable but does not have the same angle marks on the knuckle and Sorby advise you to keep this at the original 120 degrees. It also has a fixed step on the shaft rather than an adjustable collar to control how far the tool holding part of the jig drops into the chosen hole on the "long grind jig".

http://www.getwoodworking.com/news/arti ... cure/25849

I've seen the P=3", Jig setting = 6 advice that Paul gave above for making an Ellsworth grind with a tormek, but the pro-edge isn't quite the same animal and I believe that the tormek jig settings CAN'T simply be transferred to the pro-edge as the rest of the two systems are mechanically a bit different. The tormek adjusts the bar to wheel distance (variable but with two standard settings "A " and "B"), the pro-edge adjusts the distance by using a fixed bar and a connecting "boss" with holes that give 3 preset distances. I've never seen anything comparing the geometry of these two systems.

I would love to hear from someone doing the original Ellsworth grind on a pro-edge, not a tormek. I don't have any hang ups over this grind being lots better than any other, I just don't want to trash my original factory reference point until I know how to replicate it

By the way, this is the best video i've found so far on how to use the pro edge to make a long grind. I don't think it's exactly like the Ellsworth butI imagine it's close. I'm guessing this is the online guide that you refer to .

https://www.youtube.com/watch?v=k-nTHpfcwkQ

and there's some informed discussion but not a simple answer a few posts down in here:

http://robert-sorby.freeforums.net/thread/57/pro-set

 

[CHJ]

I've settled for a fixed jig angle (120deg) and use the three hole pivot block and one extra length protrusion to get all the nose profiles I like on my go-to gouges.
I suspect someone else taking them to their lathe and setup would find them less than ideal.

 

[marcros]

I am fairly sure that random orbital bob had had some discussions about this on a pro edge forum. I haven't seen him post for a couple of weeks, so he may be on holiday.

 

[Chris152]

You're right, Sideways - they've clearly become quite different. I have a fingernail gouge here that I'll have a go at today if I get a chance - I sometimes accidentally get a slight convex when I dwell too long on the shoulder, so I'll try some more of that and show what I get...

 

[Mark Hancock]

A true Ellsworth grind is done on a gouge with a parabolic flute with a 60 degree angle. The parabolic flute clears easier than normal U shaped flutes. With the Pro Edge you need to get the 3 hole barrel bit. IMHO it should be included with the Deluxe version.

 

[Chris152]

Thanks Mark - I guess it's less Ellsworth's specific gouge and more long wings with convex shape I want to try. And I agree about the extended barrel being included, not so deluxe without it.
For the moment, I've tried to get the convex shape on a fingernail grind. It worked to a point, but the knuckle of the elbow contacts the housing to the side stopping further movement - if that makes sense, and if this photo helps clarify...

Here's a side shot of what that accomplished (reground, not sharpened):

Maybe with the longer wing that approximates to Ellsworth, that amount of lowering of the shoulder would be enough of a convex to make a difference?

EDIT - I just realised, if I set the bevel angle to be less steep (it's on 50 in the photo, which I've been using til now) there's much more room for the knuckle to get lower on the shoulder - even 45 offers more room. But then I'm moving further from the 60 degree bevel of Ellsworth? Struggling to get my head round this...

 

[Chris152]

I've been using that grind today and like it. Not so different from when it was a fingernail done with the standard Sorby settings, but easier to see what's happening when sheer scraping/ peeling, and it generally feels better to me. There might be no good reason for that.

But what's clear is that Sorby have completely failed to give guidance on the effects of the different settings/ positions when using the jig and extension (this has been asked for a few times on the Sorby forum). Looking at the Tormek guide's not the same, as that's using a circular stone (as you say, Sideways). I was tempted to try some different combinations but that was going to cost me the gouge. It'd only take a few hours to record the different outcomes.

To my eye, the extra long grind in the Sorby video looks too long and too pointed to approximate to Ellsworth? I might give a regular long grind a go tomorrow, using 35 degrees for the wings, 50 degrees for the bevel and the centre hole on the extension to guide it (which increases the 50 degrees to a little more, judging by sight), and then rounding off the shoulders as I did on the fingernail above. Unless anyone tells me this is a bad idea!