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A question over on the Tormek Facebook group about whether an 8" CBN wheel could be used instead of a 10" one got me thinking about angular velocity.   In practice the 8" wheel would work (ie would fit) on a T7/T8, but the grinding surface would be passing the edge at a slower speed due to the smaller radius.  So all other things being equal, a 10" CBN wheel (or diamond wheel, or SG) will cut more efficiently than an 8" one because it's passing more quickly by the edge.   I was familiar with that concept, but it's been more than two decades since I looked at the relevant formulas, so I did a bit of a refresher this morning and turns out it's simpler than I thought... Angular velocity is directly proportional to radius - so the grinding surface of a 10" wheel is travelling 25% quicker past the edge than an 8"one.   That's relevant information for the person considering the 8" CBN wheel, but probably also for those considering at what point their SG is worn enough to replace...  As the diameter shrinks, more time is required to achieve the same result... 

Hi All,

FYI - Some of you may have already come across this, but a very fascinating project is underway by Australian Knife Magazine and Knife Grinders (forum alumnus Wootz). 

Really interesting to see knives put through their paces straight 'out of the box'.  I like the concept - assessing quality in the total absence of marketing. 

https://www.australianbladeforums.com/vb4/australian-knife-magazine/46339-independent-catra-testing.html

The work is funded by donation, and donors can even request brands to be tested.  For now it's focused on chef knives but eventually other types including EDC et al will be run.

https://youtu.be/bhkk8gbzryg


Early data has Global in pole position, but let's see how this unfolds.  I'm intrigued!

http://knifegrinders.com.au/CATRA-report.htm

Hi All,

I'm going in circles this morning and hoping that the forum can spare me from an afternoon of frustration.  I've been working on a Global, and for some reason I can't figure out I can't seem to get to the apex of one bevel about an inch from the heel and two inches from the tip.  See photos attached showing the problem area, plus the opposite side of that same part of the knife (with a clean edge)... I've also attached a shot of my jig set-up.  I've tried flipping the knife around 180 degrees, moving the jig forward and backwards along the knife and even deeper and shallower within the jig. 

I'm currently on the SG-250, coarse graded, but have also tried my DC-250 without success...

Does anyone have ideas or experience this where one part (and one side) of a blade just won't take an edge?... 

Thank you in advance for any help or advice. 

When holding the adjustable stop of the SVM45 in one hand and the clamp in the other there is some play between the two (ie they can move laterally by a few mm independently of one another).  This happens with all five of my SVM45s, so I assume its a constant feature.  Given the precision of all things Tormek I was wondering if anyone has tried to prevent this movement via o-rings, thread tape or other ideas?  I have to say I don't notice any performance issues with this, and grinding in one direction across the stone means would be consistently pushed to one side...  It's just that with all another aspects of sharpening needing to be millimetre perfect, this jiggle seems like an outlier to me.

Thanks!

... Everything must be Sharp   

I've been sharpening a few Victorianox blades recently that are very thin (0.6mm behind the edge).  I would normally use 15 or 20dps but I've been disappointed with the sharpness I've been achieving.  It could be that I need to optimise my honing more, but I was wondering also if such a thin blade would be better suited to a narrower edge (10-12 dps)?  Maybe there isn't enough 'room' for 20dps?

Thanks in advance for any advice...

Hi All,

I thought to share an issue I had with my US-430 extended support. The welds holding the horizontal bar to the supports weren't very tidy, and the blobs sticking out interfere with passage of the knife jig if you're using it at a low angle. 

I should have taken a photo before I started grinding the excess weld off, but you can probably get the idea.  Anyone else have this issue, or was it bad luck for me? 

I've gone as close as I dare with my grinder, and will now finish it off on the DC-250.



 

Hi All,

A new one for me...  This is a salmon knife brought to me for sharpening and I've never done something so narrow before...  The blade looks to have been sharpened extensively to the point where it's now very thin, and combined with its length makes this tricky to set up...  The only way I can think to get a grip on it is with the SVM-00 as per my photo... But it is probably going to flex when I get out towards the tip.  I could possibly grip directly on the blade if I went for a very high angle (>25 dps) but I don't think that edge would suit its intended use...  And with the curved heel I'm wishing I already had my PPC.  Any ideas on how to tackle this would be greatly appreciated!

Thanks and all the best,

Brad

Hi All,

I have an BGM100 mounted for use on my grinder but initially it sat a bit too low and so is set on a block of wood. Unfortunately the wood seems to flex a bit which spoils precision and gives away some of the advantage of having the BGM.  Are there any pre-fab solid blocks available for boosting the height of the BGM, or does it need some DIY engineering?  It would be useful to have such a thing for the XB100 as well, to use for paper wheel honing...

Thanks in advance.

B

Hi All,

This is perhaps a silly question and could only really get asked amongst Tormek junkies. The question came to me because I realised after using the stone grader and then grinding a knife the stone is wearing away, and so presumably the grit is changing.  If graded to 250 then presumably the grit goes up, and if you've graded to 1000 the grit would go down.  Presumably then if one kept going for long enough in those two situation the stone would eventually reach some sort of equilibrium.  I'm sure it depends on what is being ground by the stone, but lets say for a stainless steel knife, where would the settling point be? 

All the best,

Brad

Hello All,

My first post on the forum after being a reader for so long. This is a great community and I appreciate all the shared knowledge.

One thing I haven't been able to find info on (here or elsewhere) is whether the water (with Anti-corrosion) needs to be changed when moving to different diamond wheel grades (from DC to DF to DE)?  Up to now I haven't been doing that since I normally only do small sharpening sessions it seems a waste to throw it away each time.  But the question came to me after reading that water should be changed when switching from SG to SJ which I was instinctively doing anyways.  If I know I'm sharpening the next day I'll decant the leftover water+AC into a jar and re-use it, but should I in fact have three jars (one for each grade of diamond wheel)? 

A separate but related point - should the diamond wheels ever be washed or rinsed?

Thank you all!