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https://youtu.be/uj8P6O-qIYs
Here is a Tormek Video for gardening tools. Minute 53:53 shows a brush cutter blade sharpening.

Thanks... Very useful! I have blades like that one, which do have straight edges. The Echo blade however comprises a recurved section in between the triangular tips.

Thanks for all the replies.

The blade is an Echo part. I have a brand new spare blade, and indeed, the curved parts that join the triangular tips are ground to a bevel. It's an extremely coarse bevel, to be sure, at least 30 dps, but it is a bevel nevertheless. From that stock image that bevel is not so visible, but it exists on my blade. The flat triangular parts don't pose any difficulties to sharpen like normal blades.

Thanks for confirming what I suspected with the diamond wheel. I will attempt it freehand with the SG-250, which I have created some generous radii on the edges.

Hi,

From the various instructional videos I've seen about sharpening recurve blades, the central theme seems to be that the grinding wheel must have have a radius on the edges, over which the recurve section is carefully ground.

This is fine with wheels like the SG-250, but how about if you want/need to use a diamond wheel like the DC-250? As I understand it, the diamond wheels consist of a rigid cylindrical form on which diamonds are deposited - the edges cannot simply be ground over to make a radius. The edges are always going to be 90°

Any thoughts then on using the Tormek diamond wheels to grind recurve blades?

TIA,
Nico

PS: I am attempting to re-establish the edge on a cutting blade for a brush cutter. Kind of looks like this:

It's funny because I've sharpened dozens and dozens of blades on my T-8 before and this has never happened. Something strange about the Santoku blade profile. I will definitely have to pay more attention next time.

I had a go resetting the profile by grinding flat against the side of the SG-250 stone. I don't have a multi-base so I did it kind of freehand, but I was able to set a stop on the USB which the KJ-45 stop could rest against to give me a consistent angle from side to side. I found the approximate edge angle using the marker method.

After gently grinding on the side of the stone a few times, keeping the blade perfectly flat, the profile became dead straight as expected. No light could be seen shining through from the other side. Yay! Then I switched to regular grinding using the KS-123 angle setter at the 12 DPS I used originally, and cleaned up & polished the edge.

Results are below. It is a lot better than it was! But I detected a hair of recurve creeping back again into the profile from the final sharpening. I must be making the same mistake as before.

Thanks for the tips everyone. Now I can return the knife to my friend without so much egg on my face 

BTW I was horrified to see how much material I had inadvertently removed from the heel as witnessed by how close the edge has become to the grantons 


 

I'm attempting to sharpen a kitchen knife which has a plastic, sloping handle that extends all the way to the blade edge (image 🅐). Grinding one edge of the blade is OK (image 🅑), but grinding the other edge (image 🅒) the plastic handle touches on the stone wheel when the knife is positioned at the start of the blade. I'm not quite sure why this is - maybe the plastic handle is thicker on that edge? Theoretically it should be symmetric, so more investigation is needed.

So I am wondering if there is a "best practice" for this style of knife. I played around with grinding it with a pivoted jig (image 🅓), which may also be better done by clamping the knife in the jig at a severe angle so the jig stop runs parallel with the USB, but it doesn't feel right.

Any thoughts?

Glad it helps. As for the diamond wheels, you probably want to make sure you have the need for them : to reshape the knife you'll need the DC, but common resharpening of carbide tools is more of a DF/DE job.

Even one diamond wheel will moreorless pay for a small versatile belt sander that will be more efficient for reshaping, but also for knifes with odd shapes, lawnmower blades, etc.

Thanks for the advice.

I watched Wolfgang's analysis of how unintended recurve mistakes happen. In my case, using too much pressure probably and overgrinding the heel was the problem. Perhaps I've been overly influenced by a tip I saw in one of Wootz' videos (below) where he emphasizes more time on the stone (in general) should be spent on the heel of a blade rather than the belly or tip. More practice required and a lighter touch!

https://youtu.be/kRZTiv6XVgA?si=Qk-cewiXPRCIQhIY&t=110

If I have any success at reshaping the profile I will post the results!

Thanks a ton for that link. Checking it out now. This could be the justification I've needed to get one of the diamond wheels 

What a great topic, I'm glad I found it before posting a new one of my own. Well, I am in the embarrassing situation of having totally botched the sharpening of a nice kitchen knife with a common Santoku profile. What makes it even more embarrassing is that the knife belongs to one of my best friends. Of course I have offered to replace the knife for my friend, but at this stage, I am wondering if there is any hope left for the edge?

To make matters worse, I am not sure exactly how things got so pear-shaped. I have sharpened dozens of knives on my T-8 by now, and I did set out to put a brand new bevel on it (12 DPS) and so I was expecting a decent amount of steel removal from the start. And I try to follow all the best Tormek practices (eg. 1 or 2 passes per side, always going unidirectionally from heel to tip, etc.), But at some point I started losing the profile near the heel, and the more I tried to fix it the worse it got. Oops.

Does anyone know whether this knife edge can be restored now, and if so, how?

For the record: sharpening was done with a T-8 with the SG-250 wheel first at #220 then at #1000. The jig was the KJ-45.

I agree with everyone here about the need for the US-430. I should have mentioned from the start that I had to buy this for the cleavers, as it was impossible to get the standard USB to work.

I'm in the middle of making my own home-made FVB and I look forward to trying that out with the US-430. The new MB-102 you mentioned Ken also looks like a pretty essential accessory.

I have some axes to grind as well (joke) so aquataur, I will also try your ingenious clamp solution!

Thanks for all those tips. I'll be sure to investigate those other jigs. I'm sure there are better solutions when there is no need to tilt or pivot.

I'm sorry, CB, could you explain a bit more what you mean by "choke up" on the handle of these longer knives?

I've got a few beautiful carbon steel Chinese cleavers that I love to use in the kitchen. The blade on the big one is about 21cm / 8¼", and the small one, 18cm / 7". Both have almost perfectly straight edges with the slightest of arcs, and they are both quite heavy.

I'll "cut" straight to the point  Sharpening these blades on my T8 seems to require a lot of practice to get perfect. Even though there is no lifting or pivoting needed at the tips like normal kitchen knives, the narrow width of the wheel compared to the long length (and weight) of the blades makes it challenging to do perfectly level (i.e. flat) pass along the entire length of the blade. I inevitable tilt the blade a fraction of a degree along the pass, and it leaves a tiny groove in the blade that then takes a lot of time to smooth out.

Apart from more practice practice practice, is there any advice on how I can improve my technique?

I wonder if my stance is off, or I should be using a different type of jig that helps to keep the blade perfectly flat against the wheel? (I use the SVM & KJ knife jigs).

Any tips appreciated!

Late to this thread, but impressed with your design jvh, thank you for posting it. I think this is going to be my next project! A question regarding how the adjusting rings are secured. I can't quite see from the photos, but it looks like you have drilled (radially) and tapped these collars and secure them with pointed grub screws (whose tips "mate" against the grooves in the guide tubes). Is that correct?

Thanks everyone, I will keep the forum posted as I learn more, for example, the exact difference.

My typical use case for this is switching from grinding into the blade with the SG-250, then switching sleeves to polish away from the blade with the Japanese waterstone SJ-250. I know the purists will (correctly) comment that most likely the diameters of the two wheels won't be identical anyway, and I acknowledge that, but I was curious to know whether (if they were), we can consistently adjust whatever difference there was by using the micro-adjust or turning the adjustment nut on the USB by a precise amount (as Ken mentioned).

Apologies if this is a naive or obvious question. I don't have accurate enough tools to measure this for myself to find the answer.

The T8 has 2 attachment bases or sleeves for the USB. One allows a vertical attachment, the other a horizontal attachment towards the front of the machine.

My query is, suppose you have a blade clamped in a jig, and you have set the appropriate angle using your favourite method, and have locked the USB into let's say the top binding sleeves. If you then remove the USB from those sleeves - and carefully - so the adjustment nut does not move, re-insert the USB into the other binding sleves, and lock it - and change nothing else - will the angle of the blade against the same wheel be exactly the same as before? Or you cannot assume this.