Tormek T7

I have a 30% off coupon from Zoro so I can buy one at a truly excellent price. I know that some people didn't like earlier versions because of the tendency of a wheel to "hollow grind" the edge. But the T7 has 10" wheels and it would seem to me that this would greatly limit the hollow grind to the point where it is barely noticeable. Does anyone have experience with the T7?

I would be using this to repair thrift shop knives and maybe grind my own blades from heat treated blanks. I also would be finishing the edge on something like Jon's awasedo after using the Tormek 4k waterstone and if the hollow is pretty mild, I would hope that the finishing stone would fix that as well...

TIA

I always wanted one of those! mainly for sharpening large plane knives 12 inches and higher. Going to have to follow this thread. Hope people who have a T7 chime in.

I have sharpened hundreds of knives on a T7 at the knifeshop I work at. The edges are better the newer the wheels are. As the stone wears down, the edge gets more and more hollow, so weaker and weaker. It is an amazing machine for doing heavy material removal in short order. There is nothing it can do that I can't with a stone though. My edges are ultimately better as well. For just putting an edge on a knife, the T7 is very quick. The stropping wheel is nice for stropping very quickl, but that makes it much easier to round an edge.

Is it also good for thinning a knife, RefGent?

As glc is aware I also plan to get one of these. I am not especially concerned about slight hollow grinding as I don't plan to go into the knife making business and the wheel coupled with my stones will be interesting to experiment with. I have looked at a few variants of this machine as well since originally discussing it with glc, including one from Record that has variable torque control. In my case I also plan to use it to sharpen chisels, plane blades and secateur blades in my workshop, along with a more standard bench gender (not water bath type) for rough trueing work on tools. What I like about the Tormek, is that the German supplier I would use also sources different grades of Japanese grind stones. The stones will wear down, but they are not crazily expensive, especially if one compares it with the cost of high quality grinding belts. The hollowness of grind is easily ascertained by drawing a 10" circle with a protractor and putting a straight edge across the tangent (near enough) at the typical dimension of the grind face on a knife. The leather strop wheel may also be interesting to use. The other potentially useful tool is a powered polisher that will take nylon, cotton and felt discs. These are inexpensive.

It is good for thinning and reprofiling. If you move beyond just using the jigs and get comfortable with it by hand it is really great to have simply as a low speed water cooled grinding wheel. Other grinders and belt sanders generally aren't. Coupled with bench stones it does open up a lot of options. I've used it to grind blades into a more useful or comfortable shape, remove chips, and grind tips back after being snapped off. If you can afford one, it really is a useful machine.

post before during and after pics while in process of grinding away at thick blades!

I'd have to experimwnt with doing whole blade profiles. I think it could be done. I would't be able to try until Tuesday when I'm in the store alone to dick around. I work there part time and my other day is Saturday, which is much busier for customer sharpening.

RefGent, thanks! It's great to have a pro with actual experience answering this.

I'm considering this machine (well, actually a T4) mainly for thinning knives. But I really don't know what I should choose: this one or a belt sander. With this machine I'm worried about a hollow, concave, profile. With belt sanders I'm worried about a convex profile.

If you can give more advice, that's highly appreciated.

Hi guys, I owned a Tormek when I first started pro sharpening on the road so I've got a few observations that I can add here from my time with it.

The model I owned was their initial version (with the 10" wheel) and micro-adjustable tool arm (I think it was called that?). I had every single attachment they made at the time and used only a fraction of them, mostly the knife (2 types) and scissor jig.

They only offered one wheel at the time, the light gray (or sometimes called the blue) wheel. This was dressed between coarse and fine surface texture using a hand held grading stone (I forget the exact name).

The Tormek is an extremely well built machine - top notch quality. I have zero complaints with it's quality and reliability. It seems like it's a decent option for someone looking to maintain their own tools but I can, and will, attest to it being a poor choice for any professional sharpening scenario.

There are a few problems that aren't apparent when looking at the Tormek but become very obvious in use as a pro. The wear rate to cut rate of the wheel is the greatest issue. The wheel does not cut as fast as it should when considering how fast it wears. I spent about 70% of my time on this machine grading or truing the wheel. Not only is this a loss of man hours it's a loss of wheel radius and that both equates to a loss of money.

Tormek retailers love to show how fast it is to cut in a bevel on a chisel, and it's true - it is, however they neglect to show us that this chisel has already been ground to the radius of the wheel on the machine they're using. If you're taking a flat beveled chisel to a Tormek wheel you will be there forever grinding in the new concave bevel and if the tool is nicked/damaged, well, good luck to you.

This can also be true of a previously sharpened tool that returns to the Tormek where the wheel's radius has changed - you have to re-grind it all over again.

For folks that want to use multiple wheels (like those offered from Japan) they will all wear at different rates which means they'll have different radius sizes where none will match up to each other. This will quickly happen after the first use.

As for speed, there's nothing slower than a Tormek. I have (no lie) actually nodded off on two separate occasions while grinding on this machine. The first time I fell slumped over and ground a hole in my shirt.

You can not use a Tormek to profile a knife. If you grind across the wheel's face you'll get flats, if you grind lengthwise down the wheel's face (the better way) you'll grind a deep groove on your stone.

You can not use a Tormek to thin a blade. Yes it can be used to slightly thin an edge but if using the jigs they don't allow for low enough angles to grind up high. If you free hand, at this speed and wheel radius, you'll make a real mess of a blade and wish you never bothered.

I eventually sold my Tormek. I found a supremely better option for my work in a belt grinder.

Thanks, Dave! That's really useful. But one additional question: if the Tormek is a problem (partly) because of it's concave grind, why isn't a belt sander a problem because of its convex grind?

I never use the stone grader. Even the coarse side femoves the stone's aggresiveness

mark76 said:

Thanks, Dave! That's really useful. But one additional question: if the Tormek is a problem (partly) because of it's concave grind, why isn't a belt sander a problem because of its convex grind?

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I don't personally have an issue with either grind type but I'll discuss it anyway....

The argument can be made that a concave grind is weak because of it's thinner cross section and that the convex grind is strong but thick and both may be correct. Is either a problem? Well maybe they are but maybe they aren't. I think it's a matter of how concave or how convex for a particular tool and/or application that will matter. For instance, I would prefer a slight concave on a bevel edged barber scissor to make for a clean crisp cut but I wouldn't want a concave edge on an axe where I'm chopping down a tree, that's the realm of a convex edge. You could, and should, argue this out for each tool and it's application to get an answer that suits each intended task.

Regarding a belt grinder, you can also make a flat bevel using the platen, giving you a third option. I don't like this option very much though, it's way too easy to burn an edge by sharpening on a platen.

I sharpen on a belt grinder all of the time using the unsupported slack section of the belt. Technically I get a convex edge from this - but only technically. I use a belt grinder that has a short unsupported section of about 3" (very little to any slack movement unless I push down hard), I use stiff belts, and I crank the belt tension down as far as I can to reduce the convex effect I get. My belt edges can go straight from the grinder to a stone with just a few strokes to match up. My belt edges are a lot less convex then most people get free handing on stones. I can live with that level of convexity.

I saw Murry Carter using some sort of poly-foam to back up his belt sander. He was using an arched piece to create a convex, but I would think you could use a flat piece to get an effect somewhere in between a platen and unsupported section of belt.

And what of having 2 rollers to create an unsupported section of belt that would only be a few inches. I know there is an unfavorable geometry change this introduces in a smaller sag radius, but there may be an ideal separation distance for the rollers for a given belt at its max tension.

Any thoughts on these 2 points?


Rick

Dave, I understand. But say I want to thin a wide-bevel knife. Or even an almost full-flat grind knife over the entire blade, like a Kato. Could I reasonably do that with a Tormek? Or would a belt sander be a better idea?

rick alen said:

I saw Murry Carter using some sort of poly-foam to back up his belt sander. He was using an arched piece to create a convex, but I would think you could use a flat piece to get an effect somewhere in between a platen and unsupported section of belt.

And what of having 2 rollers to create an unsupported section of belt that would only be a few inches. I know there is an unfavorable geometry change this introduces in a smaller sag radius, but there may be an ideal separation distance for the rollers for a given belt at its max tension.

Any thoughts on these 2 points?


Rick

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I do the same as Murray sometimes when finishing knives that have deep concave ground bevels like he makes. I have a couple of radiused platens but most often use a home made version that I coat in soft graphite belting. It works pretty good for my needs.

I'm sure that a small unsupported section of belt can be used like you mentioned.

mark76 said:

Dave, I understand. But say I want to thin a wide-bevel knife. Or even an almost full-flat grind knife over the entire blade, like a Kato. Could I reasonably do that with a Tormek? Or would a belt sander be a better idea?

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I feel that the Tormek would be a very bad choice for this particular task. You'll end up with a whole bunch of grooves (like 10mm wide) down the blade that will need blending. Now if you had a really large wheel like they have in Japan then you'd be talking about a whole different thing.

Given your options I'd select the belt grinder.

mark76 said:

Dave, I understand. But say I want to thin a wide-bevel knife. Or even an almost full-flat grind knife over the entire blade, like a Kato. Could I reasonably do that with a Tormek? Or would a belt sander be a better idea?

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I suppose that you could use the wheel lengthwise down it's face vs across and thin a knife this way. Tricky though.

I forgot to mention that you can buy diamond (or CBN?) wheels for the Tormek. This would allow for a constant wheel radius to be maintained and likely a fast cut rate (at least for a while anyway). I recall a source in the UK that custom makes them.

I was thinking of trying it lengthwise like you said, sort of like automated drawfiling, but definitely tricky like you said. I should make it clear, I'm a professional in the sense that I am paid to sharpen and though I do have a few years of experience, there are many people here who know more, which is why I am here.

RefGent said:

I should make it clear, I'm a professional in the sense that I am paid to sharpen and though I do have a few years of experience, there are many people here who know more, which is why I am here.

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Hey we're all still learning, it's all good.

Thanks, guys!!

mark76 said:

Thanks, guys!!

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Anytime!

Here's that UK source of diamond Tormek wheels...

http://www.t-jtools.co.uk/diamond-and-cbn-wheels/tormek-replacement-diamond-coated-wheel/

Have you guys considered something like this?

[video=youtube;adVpwEu4rfc]https://www.youtube.com/watch?v=adVpwEu4rfc[/video]

[video=youtube;Fpy6mkGwjfc]https://www.youtube.com/watch?v=Fpy6mkGwjfc[/video]

Yeah, that looks ideal for my purposes. And for those of any sharpener (and by sharpener I mean somebody who also thins knives) wanting to replace their manual procedures with an automatic one?

But how come, if this ideal, nobody uses it?

The Makita is available in the US, for example at Amazon, mixed reviews because it isn't made from stainless steel and the water feed system is poorly designed apparently but a lot cheaper then the T7...

The T7 is an industrial grade tool with a long guarantee - you get what you pay for I guess. Thanks Dave for posting the flat wheel tools. I have not seen those available over here so will do some digging.

I'm now leaning towards the Makita, thanks Dave!

Still I was thinking could one do a flat grind and also thin knives by using the side of the wheel and free handing it rather than using the front. So one would turn the machine 90 degrees from its usual position and remove the guide completey?

(The trouble with the Makita is that is it really messy and also, since it it made of cast iron so it will rust if not babied)

Spending for knives and sharpening gear never ends... again something really interesting (Makita not Tormek).

mark76 said:

But how come, if this ideal, nobody uses it?

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My thoughts exactly. When you check videos from Jon and Maksim they are using this or similar device. Found it on Amazon Japan for around 25000jpy. God knows if they ship to EU and what the cost is. Additional stones are about 5000 jpy.