Grinding / shaping ?

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  • I use a mixture of belts for post HT grinding ,

    Siabite 2503 offer good value for money , good joints and last a good while , when they are a bit worn I then recycle them for roughing out profiles , micarta / g10 etc,

    I also use and prefer Norton Red-X , these leave a very nice cut on bevels and run cool ,

    And for higher grits again I go with a mixture of Norton R265 aluminum oxide in 180grit & 240grit and then 3M Trizact finishing belts .

  • Just remember , the higher the grit the lighter the touch , you will ruin a blade in one pass on a 400grit belt if you push too hard or stall it during those final passes , heat builds up extremely quick , get yourself 90% there on 36&60

    Just my self taught experiences , I'm sure others will give different opinions and advice too.

    How do you mean ruin the blade ? From heat ? I have been worried about that to be honest because a few times I have made the practice blades I have done hot enough for water to fizzle off them. Does it only ruin the steel after heat treatment or before also ? The last thing I want is brittle knives that snap etc...........

  • Heat and also finish. Heat buildup is very high with fine grit, mostly just need to be careful of thin parts like tips and edge but pressure and patience is key.

    Fine grit belts can also leave sort of divots from the seams if you run the belts too fast. These will ruin all your hard work in reaching a nice finish so need to be very careful.

    If your grinding post HT then yes, overheating will ruin the temper, however this doesnt make brittle blades, just creates non-uniform hardness. IMO grinding after HT is easier, just take your time and dont try to rush. As far as how hot is too hot? if you tried to grab some O1 straight out of the oven after tempering it would burn you quite badly. In practice that means you have a little leeway, your not going to ruin the blade just getting it hot to touch, even if it is really hot to touch but you can touch it, it is fine. Some stainless steels can take even higher temps without great issues. However, again be careful with thin parts and tips, while the part your holding is hot, the tip can be red hot and ruined. Best practice is if you are getting it so hot it vaporises water on contact, slow down and apply less pressure, it will take more passes to remove the steel but the end product wont be wasted. Also sharp belts cut faster and stay cooler.

  • @Jimmypie This list is very useful indeed, so thank you for taking the time to screenshot each of the products. What sort of 'jump' between grits is desirable? If I was to go for the Norton Red-X ceramics, do you go for some in 36, then 60, then 120, or is that missing out on some grits that are useful between those grits? I ask as I see the Siabite belts listed come in 36, 40, 50, 60, 80 and 100.

  • @hughtrimble my usual stock of belts and let's call it the running order are below , as I've mentioned before I do all my grinding post heat treat , this may change once I start hitting stainless and higher spec Tool steels in the new year but for now it is all post HT .

    36grit , I will grind to 80-90% of the bevel with this as it runs very cool and cuts very quick , so this is my most used belt , once it dulls they are recycled for roughing out profiles (pre HT) or for the hard composites like G10/Micarta/carbon fibre .

    60grit , a few passes on all bevels to remove the deep 36grit cuts , start tidying up plunges etc , again , fresh belts cut quick and clean .

    120grit , I'll use these to start bringing things to a close ,final grind heights & edge thickness , they would also be my starting grit for the flats , a fresh 120 will give you a very serviceable finished bevel by the way .

    I regard everything beyond this point as a finishing belt and so will start to get critical with heat build up , now it really is grind and dip ,grind and dip .

    180grit , now your getting to the finish , for me it's just now removing the previous grit , light passes is all you should need.

    240grit -320grit same as above, a lot of my knives will finish here if they are being acid etched or black oxided .

    Then it's Trizacts , and really as far as you want to go , but an 800grit trizact will burn an edge or tip before you even realise your touching the belt , be warned :)

    Just my methods , I'm self taught and it seems to work for me .

  • Sorry for being a grinding noob - buying Trizacts, which don't like to conform to nice grading standards.

    If I've just done the 240 grit Norton R265 aluminum oxide, next Trizact grade to go to would be, say:

    A45 (320 grit equivalent?)
    A30 (400 grit equivalent?)
    A20 (500 grit equivalent?)

    And perhaps stop there for now, as from what you've described @Jimmypie, taking a :poo: on things with the Trizacts can happen really rather quickly. Or should I just keep on trucking upwards?

  • What I mean is that they will ruin a blade in a nanosecond. All that hard work screwed. Not from heat buildup so much (though that as well), but if you approach the platen at slightly the wrong angle, they are SO efficient, and also give less tactile/haptic (and audio) feedback, that they will cut in and you then have a vertical gouge up your blade.

    Of course that happens with ceramics as well but unless I'm dreaming, it's harder to do.

    You'll see what I mean. Unless I actually am dreaming :)

    My grinding is still so crap I assume that all my blades will end up with some kind of fault like this but I do try and minimise them, hence my use of the TriZacts is sparing, and very careful.

  • Ceramics (not sure of the make, SAIT I think?), and only Trizacts if feeling brave enough.

    I have some wonderful finishing belts which are almost 'furry', I call them my furry belts anyway. I have no recollection of where or from whom I got them, but they are superb at applying a "brushed" finish to a blade and they hide all manner of sins! I'll try and find out what they are called.

    My usual workflow is:

    1. 36, 60, 80, 120. Looking good! I'm a pro!
    2. 240, 320, 400... hey where are these wobbly reflections coming from?
    3. Ah dammit another gouge, back to 120 for a bit...
    4. 240, 320, 400... bloody reflections, time for the....
    5. Coarse furry belt... hey that's better! Needs a bit more finesse though so...
    6. Fine furry belt..... and I'm a pro again!

  • Well here goes, first real attempt at grinding.
    Discovered I am good at grinding with my right hand holding the knife and left thumb.
    The other way I am awful and lucky it did not ruin the blade completely.
    The biggest problem is either end of the grind.
    The tip end tends to stay thick and the plunge line is hard to get height.
    The other issue is uniformity, I tried to do both sides identical but I just could not get them to match.
    I slipped on one side and messed up the plunge line. Maybe will polish out.
    However the blade will cut as good as any I guess, just not as good as I am aiming for.

  • @xellos99 could try using a jig or a plunge guide, I've had good results with both. However, I've just found that regular practice is key - been grinding a blade every night since before xmas, got piles of them all over the place! Until I got some waterjet cut folder blade blanks, I was just profiling the blade shape using wickes mild steel and then (much better) GFS 01 steel (i.e. making no handles) and working through 36 and 60 grits with no expectation I was going to produce something worth progressing. Funny but its like you progress one step forward and two steps back, as a result of getting more confident and trying something new, then messing up but learning from the experience. Very often, something will just click and you have a minor eureka moment but in the process you'll probably have ruined what you were working on. Pleased to say I'm able to produce consistent results in either direction and I'm sure you will too very soon.