KME Lapping Film Progression

[skeeedunt]

The full KME kit comes with 9 6 3 1 0.5 and 0.1 micron diamond films. Wondering if this full progression is necessary, or whether I could get most of the benefit while skipping around a bit, 9-3-1 or 6-3-0.5 or similar.

Supposedly 9 micron is equivalent to 1800 grit, so it would seem pointless to go from the 1500 grit diamond hone to the 9 micron film, unless there are additional qualities of the film that I’m not understanding.

Mostly just playing around and trying to get a mirror edge, I realize (thanks to all the fine posts here) that a lower grit edge is often more practical. Wondering what folks experience here is, and whether I’m just shooting myself in the foot trying to save time (and money).

 

[Mr.Wizard]

Supposedly 9 micron is equivalent to 1800 grit, so it would seem pointless to go from the 1500 grit diamond hone to the 9 micron film, unless there are additional qualities of the film that I’m not understanding.

I haven't used these particular films but I caution against translating grit this way. The nature of the abrasive and backing can have a dramatic effect on its performance and apparent fineness. I believe lapping film is a resin slurry coat on a poly film backing which is very different from electroplated diamond.

 

[bucketstove]

The full KME kit comes with 9 6 3 1 0.5 and 0.1 micron diamond films. Wondering if this full progression is necessary, or whether I could get most of the benefit while skipping around a bit, 9-3-1 or 6-3-0.5 or similar.

Supposedly 9 micron is equivalent to 1800 grit, so it would seem pointless to go from the 1500 grit diamond hone to the 9 micron film, unless there are additional qualities of the film that I’m not understanding.

Mostly just playing around and trying to get a mirror edge, I realize (thanks to all the fine posts here) that a lower grit edge is often more practical. Wondering what folks experience here is, and whether I’m just shooting myself in the foot trying to save time (and money).

Hi,
Film is flexible/squishy/forgiving/conforming, where as hones are rigid

https://support.wickededgeusa.com/portal/kb/articles/grit-comparison-table
5 micron Diamond Paste
versus
1500 Grit diamond stone ( 5.00 micron )

 

[skeeedunt]

That makes sense, and the pictures certainly show a marked difference. Would explain why pics I’ve seen of knives coming off the 9 micron films were so much more refined than I got off the 1500 stone (I assumed it had more to do with my lack of skill, not getting lower grit scratches out).

So starting with the 9 micron makes sense. What works for you folks in terms of grit progression from there? I’ve heard 3x as a general rule, so 9-3-1 perhaps?

 

[Mr.Wizard]

So starting with the 9 micron makes sense. What works for you folks in terms of grit progression from there? I’ve heard 3x as a general rule, so 9-3-1 perhaps?

Yes, that's a good start. If you want to deep dive research recommended procedures for the metallographic sample preparation of ferrous alloys, for example https://www.metallographic.com/Metallographic-Preparation-Procedures/1095-quenched-steel.htm recommends exactly a 9μ-3μ-1μ progression, though that is with diamond compound rather than lapping film.

 

[l1ranger]

if mirror polish is your goal - I like every small step I have available.
if I have 9 6 3 1 0.5 and 0.1, I'm gonna use 9 6 3 1 0.5 and 0.1.

 

[PeterS84]

I like the 9um film because it does a good job of refining the edge left after the 1500 stone and also does a good job of cleaning up the scratch pattern on the bevel. I've done progressions where I skipped from the 1500 stone to a 4um strop, then into the 1, 0.5, and 0.1 films and the level of polish isn't as good as when I do the full progression from 1500 -> 9um, on down. I've even gone further than the 0.1um film and used a 0.05um strop followed by a 0.025um strop -- ridiculously sharp and the polish is pretty beautiful as well.

 

[kreisler]

if it's about money, effectivity and maintainability, you could try the PTS method on the KME

actually you (and everyone else) should imho try it first. very satisfactory thing to perform. you'll be super pleased by the result. then, if you still feel like investing more $$$ for commercial quality then by all means buy the commercial set in addition.

 

[skeeedunt]

Thanks folks. Sounds like opinions vary a bit, but leaning towards a tighter progression. Thinking I’ll grab the 9um and 6um to play around with and go from there.

if it's about money, effectivity and maintainability, you could try the PTS method on the KME

Appreciate the suggestion. It’s about money in so much as I don’t want to waste it, but I don’t mind spending a bit on the right solution.

I need to read your thread more thoroughly, but the PTS solution definitely looks interesting and more flexible. Might be something I dig into later on. For now I’m drawn to the consistency and simplicity of the pre-configured (and same thickness) KME glass blanks and tapes. Once I have more experience and confidence I might start trying other things.

 

[kreisler]

Fair enough skeeedunt !
btw seriously, that was your 5th post within 6.0 yrs of BF membership? Wow haha

Good luck with the KME tapes. I am sure they're great stuff. Just know that each KME tape only lasts for very few knives until you're "forced" to bin it and use a fresh one. Same with the PTS method, the loaded PT is good for 1 knife only then one must remove the blackened tape to keep the wood blank clean. It's been a while since i used a guided system for my knife but it did produce the cleanest polished edges, so i kept 1 or 2 show edges from that time.