Cbn/diamond wheel on tormek

[Giles55]

Hi all,
I am at a maker space on the woodturning team, we allowed a tormek wheel to get really small and now the full size replacement means effectively regrinding every tool because of the difference in diameter. I spent more than 2 hours on a 3/8 ths skew and didn't even get 2/3 rds done. We have lots of tools, it could take weeks to resharpen with the standard wheel. I see there is a diamond wheel available but is it going to be quicker and will it last? I have read reviews which claim the tormek diamond wheels simply don't last. I believe it might be possible to get a cbn wheel from a different brand and fit it to the tormek. I have read much more positive reviews about cbn. If anyone has experience of using cbn or diamond on the tormek I would love to hear, what grit,
is it faster than a standard wheel and what is the longevity like.
Thanks

 

[D_W]

diamonds are electroplated. The quality of the plating and how much hold it has varies all the way up to something like the DMT flattening plates. If the electroplate is similar to most hones, I you'll find the wheels seem really fast for half an hour or an hour and then get slower quickly and stay there but get very slow over time. I have taken pictures (microscope) of diamond plates and found that what's left after a while is only uniform bits of the smaller diamonds.

CBN will slow down, too.

You need a belt grinder with an 8" contact wheel and a ceramic belt to do most of the work. You will go through belts with some regularity, but no diamond anything I've ever used comes remotely close.

If you use a CBN or diamond wheel for a lot of volume, you'll still be standing over it screwing around for a very long time. A maker space is just going to have too much volume for CBN wheels, etc, to last long. I've worn out two already and they generally don't get used that heavily. Heavy compared to a typical hobbyist power tool woodworker, but they don't get used much for things like establishing brand new bevels.

If you can find a very strong grinder and get something like a "multitool" attachment, 2x48 or so, you will never spend much time grinding anything and you could use the tormek to finish more neatly (the rubber contact wheels are accurate, but not quite to the level of a tormek.

 

[Derek Cohen (Perth Oz)]

Or, since the chisel steel is likely HSS, you could purchase a 6” high speed bench grinder and 80 or 180 grit CBN wheel. Use the Tormek blade guides with it (ala BGM 100).

Regards from Perth

Derek

 

[Sideways]

CBN for HSS on a bench grinder. It generates very little heat. Better than diamond for HSS.
Diamond for sharpening carbide.

Listen to the other gentlemen. They know what they are talking about.

 

[D_W]

Or, since the chisel steel is likely HSS, you could purchase a 6” high speed bench grinder and 80 or 180 grit CBN wheel. Use the Tormek blade guides with it (ala BGM 100).

Regards from Perth

Derek

not singling your comment out for any reason other than experience with wear. it'll wear the wheels out, but maybe regular purchase of them wouldn't be a big deal.

A contact wheel on a belt grinder is probably somewhere around (time wise) five times as fast as a grinder with a hard wheel. but only if the belt grinder is high speed enough to take advantage of the belts (like 4500+ linear feet per minute. the more the better).

 

[Sideways]

Question for DW please because I know you sharpen a lot.
Over here in the UK, a ceramic belt for a Sorby pro edge is maybe £3.50
A budget 8" CBN wheel (80 or 180 grade) is sub £100 at sale time.

I've worn out a couple of coarse pro edge belts reshaping lathe tools. They are no where near as long as knife grinder belts mind and a pro edge has a MUCH slower belt speed than a proper knife grinder too.
I've reshaped a couple of tools on a new 80 grade CBN wheel as above and being new it just ate the HSS in seconds and didn't appear to touch the wheel.
Would you expect a CBN wheel to be substantially worn out after the equivalent work that would wear out 30 pro edge belts ?

The answer would help us understand the consumable cost. Time wise I've no idea.

 

[Paul Hannaby]

Changing from a small wheel to a large wheel shouldn't necessitate regrinding all the old bevel out so I'm not sure why you are trying to do that. All you need to do is to sharpen the tool and create a small bevel behind the edge, it really doesn't matter if there is still some of the old hollow grind farther back. Grinding all the old bevel out is just wasting time and steel!

Re CBN and diamond, CBN is used on high speed grinders in preference to diamond because they last longer due to depletion from a chemical reaction between the carbon in the diamond or boron in the CBN. The reaction takes place at 150°C on diamond and 750° on CBN so isn't a problem for CBN at normal grinding temperatures but results in diamond wheels being depleted faster. On a water cooled wheel, this is irrelevant as the water keeps the wheel at room temperature so diamond wheels are better than CBN in this instance.

 

[Giles55]

Changing from a small wheel to a large wheel shouldn't necessitate regrinding all the old bevel out so I'm not sure why you are trying to do that. All you need to do is to sharpen the tool and create a small bevel behind the edge, it really doesn't matter if there is still some of the old hollow grind farther back. Grinding all the old bevel out is just wasting time and steel!

Re CBN and diamond, CBN is used on high speed grinders in preference to diamond because they last longer due to depletion from a chemical reaction between the carbon in the diamond or boron in the CBN. The reaction takes place at 150°C on diamond and 750° on CBN so isn't a problem for CBN at normal grinding temperatures but results in diamond wheels being depleted faster. On a water cooled wheel, this is irrelevant as the water keeps the wheel at room temperature so diamond wheels are better than CBN in this instance.

Well, with the 3/8 ths skew the new bevel doesn't reach the full width of the cutting edge so only part of the blade has actually been sharpened. This is because the multi jig is not accurate for the small skew, it moves in the jig. The large oval skew has ground better but still requires more grinding in order that the front contact point reaches all the way across the cutting edge. Yes I can stop sharpening once I get contact all across the cutting edge but even achieving this has been complicated by the huge difference in diameters. Personally I wouldn't use or purchase a Tormek if you paid me, I grind freehand on a normal grinder ( easy for anyone with an average ability) but at the space we have to accommodate complete lack of ability, hence the jigs and the tormek.

 

[cowtown_eric]

Also at a makerspace I am, and we have a tormak knock-off with almost the ful assortment of tormak jigs. I am with Giles 55..much prefer the bench grinder with a white wheel. Ever so much faster and versatile. The bench grinder has Lee Valley grinding platforms

I've recently bought a 6" diamond plate from a jewellers supply for 35$ CDN, mounted it on a chinois slitting saw arbor and chucked it in the drill press to touch up some carbide metal bits- but that stays in my locker.

Two grinders thee, the one at the back is 1750 rpm, and you may notice it has an expandable rubber drum(Max rpm 1750- or else the sandpaper sleeves just explode!) Great variety of sleeves available at Lapidary stores, but it so unfamiliar to even the other member whom teaches sharpening, that Ihad to take it off! (people thought that because the belt was loose on the wheel that they wanted to "fix it!" !!)

Makerspaces are such great fun!

 

[D_W]

Question for DW please because I know you sharpen a lot.
Over here in the UK, a ceramic belt for a Sorby pro edge is maybe £3.50
A budget 8" CBN wheel (80 or 180 grade) is sub £100 at sale time.

I've worn out a couple of coarse pro edge belts reshaping lathe tools. They are no where near as long as knife grinder belts mind and a pro edge has a MUCH slower belt speed than a proper knife grinder too.
I've reshaped a couple of tools on a new 80 grade CBN wheel as above and being new it just ate the HSS in seconds and didn't appear to touch the wheel.
Would you expect a CBN wheel to be substantially worn out after the equivalent work that would wear out 30 pro edge belts ?

The answer would help us understand the consumable cost. Time wise I've no idea.

I think the CBN wheel will continue to cut for a long time, but it will be very slow compared to what you remember it as new, and there's only one thing that happens when wheels get slow. We add pressure. we like wheels to be crisp fresh abrasive to cut off material efficiently and spark it (if the steel sparks well) sending the heat away from the edge. As the abrasion gets less efficient, you do more rubbing and burnishing vs. relatively violent rowing of the steel.

I can't speak for the pro edge as I don't know what really happens at 700 feet a minute. At 2200, my slow sander is only just able to make use of ceramic belts the way they're supposed to be used, and the 5000-ish ft/min contact wheel is noticeably more suitable. they thrive on speed.

what does sorby recommend for heavy work? the blue or green belts? silicon carbide belts (those are generally used for wet work from what I understand, like with glass, etc, and some types are intended for stainless steel).

My initial high quality wheel, btw, is 80 grit CBN. I remember when it was new, it left much deeper grooves than a 46 grit pink wheel (bigger, but more gentle grit). It's a shell of its former self and it hasn't done the work that 7 ceramic belts on the belt grinder would do - not even close. I could cut at least 20 bevels from square hardened bar stock on a ceramic belt. maybe 30 or 40. Each of those is a multiple of refreshing a hollow or turning tool.

Sometimes I wonder if the trouble over time was due to speed and pressure - as in, would I have been better off getting a full speed 8 inch grinder (have two of those now, but didn't at the time) to use lighter pressure and maybe more of the CBN grits would stand up better.

 

[D_W]

(not advocating a belt grinder for the average person, though - the fairly crude multitool attachment - and it is definitely crude compared to a "real" belt grinder....

....plus the associated good quality taiwan grinder is somewhere around $900 now. The pro edge is very expensive here ($540-$690, I guess depending on what you get), but that could be due to distribution rights. I like the idea of the pro edge. It would be nice if they would've given it the power and speed to do light shaping along with sharpening.

 

[Sideways]

Thanks. I appreciate that !

Sorby sell a range of belts for the pro edge. They pretty well cover all the bases.
I tried both zirconium and ceramic at the coarse end. My impression is that Zircon blunts faster and you end up with a lot of rubbing and generating heat. The belt feels blunt long before it's close to being rubbed bare. I prefer the ceramics across the board.

I like the pro edge. It's well made for an enthusiast woodworker. Decent jigs and the belts make it versatile.

One day I may design and build a knife grinder with a proper contact wheel, much more speed and power plus a platen that will still work with pro edge jigs. But there are lots of projects in the queue before that...

 

[Giles55]

Also at a makerspace I am, and we have a tormak knock-off with almost the ful assortment of tormak jigs. I am with Giles 55..much prefer the bench grinder with a white wheel. Ever so much faster and versatile. The bench grinder has Lee Valley grinding platforms

View attachment 148624



I've recently bought a 6" diamond plate from a jewellers supply for 35$ CDN, mounted it on a chinois slitting saw arbor and chucked it in the drill press to touch up some carbide metal bits- but that stays in my locker.

Two grinders thee, the one at the back is 1750 rpm, and you may notice it has an expandable rubber drum(Max rpm 1750- or else the sandpaper sleeves just explode!) Great variety of sleeves available at Lapidary stores, but it so unfamiliar to even the other member whom teaches sharpening, that Ihad to take it off! (people thought that because the belt was loose on the wheel that they wanted to "fix it!" !!)

Makerspaces are such great fun!

Hi,
What is amazing to me is that your makerspace looks identical to the place I go to. It's all about utility not making a pretty workshop.
I am leaning towards grinding the skews on my grinder at home and suggesting people hone them with a diamond hone until they need grinding again. I suppose we could get a grinder at the space which just I would use. Quite incredibly in my opinion 99 per cent of the wood workers I have met are completely unable to sharpen anything. Tools get ruined on a regular basis because of completely delusional people thinking they are expert sharpeners. Just recently someone who said they were a seasoned sharpener put five different bevels on a chisel and they were using a jig. They were totally satisfied with the result.....ha ha ha.

 

[Giles55]

Also at a makerspace I am, and we have a tormak knock-off with almost the ful assortment of tormak jigs. I am with Giles 55..much prefer the bench grinder with a white wheel. Ever so much faster and versatile. The bench grinder has Lee Valley grinding platforms

View attachment 148624



I've recently bought a 6" diamond plate from a jewellers supply for 35$ CDN, mounted it on a chinois slitting saw arbor and chucked it in the drill press to touch up some carbide metal bits- but that stays in my locker.

Two grinders thee, the one at the back is 1750 rpm, and you may notice it has an expandable rubber drum(Max rpm 1750- or else the sandpaper sleeves just explode!) Great variety of sleeves available at Lapidary stores, but it so unfamiliar to even the other member whom teaches sharpening, that Ihad to take it off! (people thought that because the belt was loose on the wheel that they wanted to "fix it!" !!)

Makerspaces are such great fun!

On a more positive note, I am awaiting my first ceramic wheel for my grinder, I can't wait. I have Shapton pros for my hand Sharpening. I have used all the different types of stones and I can say categorically, ceramic stones are incredibly good, better than anything else I have sharpened on.

 

[D_W]

Hi,
What is amazing to me is that your makerspace looks identical to the place I go to. It's all about utility not making a pretty workshop.
I am leaning towards grinding the skews on my grinder at home and suggesting people hone them with a diamond hone until they need grinding again. I suppose we could get a grinder at the space which just I would use. Quite incredibly in my opinion 99 per cent of the wood workers I have met are completely unable to sharpen anything. Tools get ruined on a regular basis because of completely delusional people thinking they are expert sharpeners. Just recently someone who said they were a seasoned sharpener put five different bevels on a chisel and they were using a jig. They were totally satisfied with the result.....ha ha ha.

Grind and hone until a grind is needed again with a skew is a great way to go (with you doing the grinding). I don't use much more than a skew and a parting tool and there's quite a lot of turning to get through before a good even M2 skew needs to see the grinder again.

I don't think your experience with sharpening is unique. It's a constant topic on the forums, so we're all coked up on it, but George Wilson has told me more than once that he had fairly experienced apprentices who just refused to sharpen as often or to the level that tools should be for fine work. they were happy to use tools that someone else freshened for them but would refuse to stop and do it themselves.

Every maker space or class work person I've talked to generally teaches basic care use and sharpening to start and has mentioned that getting students or attendees to sharpen is a constant problem.

Maybe there's a cross here with brush and pencil artists where the student artists and apprentices refuse to keep their pencils in shape and brushes clean.

 

[Jacob]

I spent more than 2 hours on a 3/8 ths skew and didn't even get 2/3 rds done.

I'd say that's about 1 hour and 50 minutes too long, on any tool.
Could do them freehand on an oil stone faster!
I always think small diameter wheels (say below 12" dia and wet) are not good for sharpening but should only be used for metal work, not on edge tools at all except for remedial work etc.
People seem to moan about the Tormek continuously, I'm surprised they are still for sale!
Flat is better, either a linisher or even better, a flat sanding disc.
Mines a 12" flat disc on my lathe headstock, with an MDF disc on the other end, charged with Autosol for polishing.