21st May 2011, 06:15 PM #1
Sigma Power Select II, #240, first impression
To add to Clinton's post earlier ...
This stone is intended for hard steel and is all that Schtoo has said about it.
I got it primarily for lapping blade backs to get them flat fast.
Tested on a 1" Titan firmer and a similar chisel (3 clover leaves on the back, can't read the maker's name, but damn hard steel).
Frankly, given my experience of ceramic whetstones, I found this comically odd.
Talk about soak up water, and leak it while in a holder, and see the water bubble up on the trailing stroke of the chisel.
But, it produces a nice paste quick smart and cuts at the same pace.
The Titan was rubbish on the back so I took the worst out by jointing the edge on a bench grinder. About 4 mm off. Then 10 mins on the Sigma and the back was flat to maybe 25mm back.
The clover leaf brand looked an easier job to begin with but it had been rehabbed and there was dubbing over about 3mm back from one edge running on the diagonal to the other corner.
10 mins on that and I had to step back to a #120 ceramic whetstone, and then return to the Sigma.
Next time I'll try Schtoo's advice to add some SiC grit to the #240 stone.
What needs attention with HCS and this stone is to clean and dry it carefully since any remaining steel oxidizes rapidly.Cheers, Ern
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26th May 2011, 08:32 AM #2
2nd use: it also grows mildew fairly rapidly, despite my taking care to dry it well.
Dunno what effect this may have on the resin bond.Cheers, Ern
26th May 2011, 12:27 PM #3
Boil it if you must, or bleach it.
There is no resin bond in any Sigma Power stone to the best of my knowledge, and in answer to my specific questions, they are all either kiln fired ceramic or sintered (pressure and heat).
Now the Select II I've not performed any durability testing on, but the ceramics are functionally immune to heat or cold to a ridiculous level. I've got a lovely picture of a pair of stones encased in ice, and the next photo is them on the stove being force dried. Thermal shock far beyond what nearly anything is put through, and both stones shrugged it all off without a hint of any trouble.
Contrary to the normal 'care and feeding' of waterstones, I've resorted to simply saying "don't hit them with a hammer and don't drop them on your toes", otherwise go your hardest, they don't get hurt easily.
Although sharpening on a frozen stone doesn't work too well.
The Select II are sintered, so there's nothing in there you can hurt. Bleach away.
(And if something goes wrong, let me know ASAP and I'll replace the stone. Not no questions asked, because I want to know details, details, details, but the replacement is not in question.)
In use, I've had mildewy stones before, and once the surface is cleared I can't notice anything untoward. Still, not a good thing to have in there.
Maybe stick them on the fire before putting them away? It'll dry them out quick. DAMHIKT.
Warning, the above ONLY applies to Sigma Power stones. Any other commerically available stone that I am aware of does require some measure of care and consideration with regards to heat, cold, chemicals and impacts. Most stones are on a sliding scale of fragility, with some disintegrating without much effort at all.
Consider yourself warned. Be careful with stones.
26th May 2011, 07:16 PM #4
Thanks for the low-down Stu.Cheers, Ern
29th May 2011, 12:38 PM #5
The Sigma Power Select II #1000 also had mildew when I pulled it out for its second run.
The aesthetics don't bother me.
Have to repair my son's Global knife after today's family lunch (yeah, he's a brand snob; it was my thank you gift for teaching a couple of my classes & he wouldn't have valued one of the better choices).
So we'll have a father-son session over the whetstones. Reckon I'll have about a 30 sec window to do some instruction. Not his thing sadly.
We'll have the #240, #1000 and #3000 in the IIs and then the Sigma Power #8000.Cheers, Ern
29th May 2011, 04:07 PM #6
... well the stones worked a treat, and are now standing on end on kitchen paper like Stonehenge with the RC air-con drying the shed out. The mildew on the #240 was gone after this session.
We did a deal of work on two Western knives that hadn't had much TLC in a while. Mundial French cook's knife and carving knife.
With the PS II #3000 it was even poss. with a bit of patience to change the bevel angle.
The Global ... good grief. Never seen anything like it.
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