how to keep gatco stones flat

[rogerxd45]

i have a gatco sharpener and i just replaced a few of the stones because they got worn pretty heavily out of shape. there is a fair amount of stone left but it is way out of flat. how do i keep my replacements from doing the same thing?

 

[rogerxd45]

no one knows how to keep sharpening stones for the gatco flat?

any help would be greatly appreciated, i really dont want to ruin any more stones

 

[Obsessed with Edges]

Saw your post yesterday, but I don't see there's much way to guarantee they'll stay flat, if they're used pretty heavily. With guided rod setups like the Gatco or Lansky, there's no way to turn stones around to distribute the wear evenly, and the rod & clamp setup will limit the wear to the central portions of the stone, because the rod's travel limits how much of the stone gets used.

You might consider picking up one or two of the Gatco diamond hones for heavy grinding jobs, like re-bevelling and establishing the new apex. Maybe an XC or Coarse diamond, then rely on the regular stones for refining the bevel finish beyond that. So long as you're not doing the heavy grinding with the regular stones, they'd stay flatter for longer.

And depending on what steels you're sharpening, the diamond may be a better choice anyway. High-vanadium steels like S30V can dish the regular stones pretty fast. I ruined two of my Lansky hones on S30V, in essentially one major re-bevelling job.


David

 

[rogerxd45]

yea i just got done reprofiling s110v s30v m390 and elmax down from their factory angle, the s30v was probably the easiest one of the bunch

is there an easy way to grind down the high spots on the stone? i was thinking along the lines of a file but figured i would probably ruin the file

 

[Obsessed with Edges]

yea i just got done reprofiling s110v s30v m390 and elmax down from their factory angle, the s30v was probably the easiest one of the bunch

is there an easy way to grind down the high spots on the stone? i was thinking along the lines of a file but figured i would probably ruin the file

All three of those steels would do much better on a diamond hone, including refining stages. They've all got high vanadium carbide content (110V is extremely high), and it'd be a never-ending battle trying to keep your stones flat sharpening them. If wanting to stay with the Gatco setup, I'd switch to their diamond set for those.

Stones can be lapped on more aggressive abrasives, like SiC slurry or wet/dry sandpaper on a hard, flat & smooth backing (glass, stone), or using a very coarse diamond plate. It's unpredictable, however, in how the grinding performance will change after lapping. Many times, stones will become much smoother and less-aggressive after doing so. If you're willing to risk it, you might even be able to flatten your stone on flat concrete (sidewalk, driveway), but no guarantees as to how it'll work out. A steel file would likely be ruined on these stones, as the stone's abrasive (probably aluminum oxide) is still much harder than the steel teeth of the file, and they'd be ground away.


David

 

[Obsessed with Edges]

I'd forgotten, there's another thing to consider in lapping/flattening the Gatco hones. As the hones reduce in thickness, either by use or by flattening, it'll affect the working angle for the hone. The vertical distance between the working surface of the hone and the guide rod will decrease as the hone wears or thins, and so the hone will 'drop' somewhat, with it's guide rod remaining at a fixed height at the upper end; that'll steepen the working angle at the contact point with the blade's edge. If one or a couple of hones are more worn than others used in the sequence, they won't all be working at the same angle.

The Lansky system uses an L-shaped guide rod that allows the hone to be adjusted up/down, to keep it's working surface in-plane with the rod, which would compensate for differences or changes in height or thickness of the hones. The Gatco has no such adjustability in that regard; it's guide rod is a fixed ~3/8" or so above the working plane of the hone's surface (when brand new), and that dimension would gradually decrease as the hone thins with wear or lapping.


David

 

[rogerxd45]

I think im going to buy an edge pro apex type sharpener next when i have the money or these stones wear out, ive heard great things and i can reverse the stones on those, plus with the infinitely adjustable angles i can compensate for stone wear, the gatco only has steps of 3-5deg where as the apex can be adjusted in far smaller amounts

i bought a diamond fine stone for my gatco a while ago and i found its much coarser then the stone fine one, it just doesnt seem to get as nice of an edge as the stone ones do,
on my new stones ive been trying to make sure i use as much of the stone as possible so it will wear more evenly since the last time i didnt pay attention and ended up grinding a rut in the center of the stone

as far as lapping them changing the angle, i had thought about that but figured its better then having a stone that is curved, at least with the flat stone the edge is flat but with a curved one i cant even begin to guess what geometry the edge will be plus it will suffer from the same issue of changing the angle since the rut will change the angle just the same as a flat stone worn to the same thickness since the stone will be the same thickness at the bottom of the rut as a lapped stone would be.

i made myself a leather strop for the gatco out of one of stones i replaced, i removed the stone and glues a piece of thick strop leather to a piece of wood that was the correct thickness so it would match the distance from the rods that the stones have. the edge i got with using the strop was just amazing, i cant believe how big of a difference it made. plus it got my bevel to a mirror polish which is a plus

thank you for all the advice