Question about paper sanding - blade finishing afer HT

Hi,

I have just spend 2 hours using sanding paper (on small wooden block as support) my first kitchen blade (monosteel O1 at 61 HRC). The blade was previously thinned (after HT) on Atoma 140 and scratches taken out with Bester 220. After little experimenting I proceeded with sanding paper in 120, 180, 240 grit (changing direction with every grit). It did not go fast, but I could see when all the previous scratches were removed. So far so good.

The problem was when I flipped the knife to sand the other side. I have used a piece of wood (which roughly shaped to follow the profile of the blade). While sanding - the loose grit from the sanding paper together with the WD40 I used as lubricant crawled under the blade, got between blade and the wood - and caused scratches (something I suspected could happen, but now I got experimental proof).

Q: What would be the best approach to avoid this happening again in the future?

thank you

Better quality sandpaper will not lose grit like lesser quality sandpaper.
I was also told you should use a piece of leather between the block of wood and the sandpapper to allow a little forgiveness if the blade is not totally uniform.

Tape the backside with blue painters tape.

A piece of tissue paper underneath towards the final polish.

I use WD as lube too in the workshop, works very well with Wa stones and EDM stones of good quality makes a nice slurry.

Some tips, that first cut across the grind marks is always the hardest, most often because you missed spots of a courser grit when down to lower grit belts, its easy to do with the grind marks running the same way. Do a brief cut against the grain with your 150-180 grit paper, and return to the low grit belt, it will show you where you missed.

Another thing I found speeds up the first hand cut is to use mixed media, paper even with backing tend to cut in a more uneven gauging type way than a stone, I mean something like an edm stone or a Wa stone, (softer). These cut very flat,

You can use thus to your advantage by making alternate cuts on the firs cut against the grind marks, firs paper, (makes deeper more uneven marks) then your hard edm stone in say 180 grit, this will quickly take the tops off the courser paper cut. And repeat until even grit.

Thanks - those are all great advices. A bit of take could indeed solve the problem.

I though that the Matador sanding paper I got from fine-tools is supposed to be high quality (well it does cut fast). I got a testing amount of 3m (self-adhesive, yellow colour) in 100, 240 and 400 grit, but that paper seems MUCH finer when compared to the same grit Matador (black on blue backing) and while self-adhesive feature seemed cool, it is not practical here as one needs to toss the paper fast - the sticking it on and taking it off takes then too much time.

Will - I do not have water in my workshop, so mixing paper and stones is not easy to do for me, but I will give it a thought.

Seems I have a lot to learn when it comes to using sanding paper :O

Im talking about edm stones. They are usual silicon carbide in binder, different grits in a small 4mm x 10mm x 100mm stone stick. They are used for flatting very hard castings available commonly most everywhere in the world. The good quality ones make a nice slurry too. I use em with wd40 at this stage, as well as paper.

I see - I had to google them. I have to admit I have not heard about these before. Indeed - this looks interesting. Thank you Will. If you could share name of the good quality ones I would be grateful

I have tried the pink eBay ones, not so good but they work.
Ones I have at the moment are "13x6x150mm GT180 HYPREZ EDM FINISH STONE"
They are pretty good, I have had faster cutting ones but these likely cut flatter,

Just find your local industrial supply and try a few see which work best for you.

Cheers

Will

Thanks : )

let's see some pics!

jessf said:

let's see some pics!

Click to expand...

I will take some this weekend. Yesterday before I posted this thread I went up to 240 when I realised, that I after all the thinning (5 ours with Atoma a then the Bester 220) I need to slightly re-profile the edge and repair the tip (which got a little rounded) and so I will only continue with the finish once that is done, since I will probably introduce some scratches I will need to remove afterwards.

I would recommend rhynowet sand papers , they cut super fast , I use 180-240-400-600-800-1200-1500 progression. For finishing tips watch nick wheelers videos on YouTube, I think he sets the standards and explains things very good .
As will said your initial grind marks are what's going to take the most . Especially if you are using not so strong motor grinder and older belts . The more you press the deeper scratches will be . Depending on the size of your platen you can do some vertical grinding to see your scratches, hope it helps . If you can get a disc sander with vfd it will cut down sanding time so much

I have hear/read positive feedback about the rhynowet paper, but I assumed it can only be found in US. Quick search revealed that it can be found in Germany and costs less (1/2) than the Matador.

Sanity check - is it this paper we are talking about?

Quick question about abrasives. The Matador uses silicon carbides, the Rhynowet aluminium oxide - what difference in use should I expect?

Matus said:

I have hear/read positive feedback about the rhynowet paper, but I assumed it can only be found in US. Quick search revealed that it can be found in Germany and costs less (1/2) than the Matador.

Sanity check - is it this paper we are talking about?

Quick question about abrasives. The Matador uses silicon carbides, the Rhynowet aluminium oxide - what difference in use should I expect?

Click to expand...

It is the Sand paper you sent the link, correct . Haven't used matador , can't comment on it but when I switched to rhynowet it was such a big upgrade from auto store or hardware store sand paper

Thanks, I am going to order some ASAP

Matus said:

Thanks, I am going to order some ASAP

Click to expand...

No problems , let me know if you need any more suggestions, I have gone through the stages and pains of dabbling into making knives with minimal tools to a setting a purpose build shop

Thank you. I will most certainly PM you with some question

Matus said:

Thanks, I am going to order some ASAP

Click to expand...

Just ordered 50 sheets boxes in 80, 120, 180, 240, 320 and 400 - I should be set for a while

Thanks for that link Matus!! Yes rhynowet is an absolute must have. I kind of beat myself up over not getting it sooner.

Glad to help. I searched quite a lot, that seems to be the best price in DE.

I use Rynowet "Red" as well, best paper I've had my hands on yet.
*Please note that I haven't used it on hardened steel, just soft cladding, wood, nickel silver, brass, copper, etc.

Hi Matus,

I had exactly the same issue as you are mentioning the first time I was sanding my blades. I did the first side and the result was perfect. I flipped the knife and did the other side, again with perfect result.
And then I checked the first side again and it was totally scratched from the debris that were left by the sanding paper

Like suggested above, after I finish the first side I tape it now with some Tesa 4843 orange tape. I really like this tape as it is very strong, yet you can peal it off easily and it does not leave any marks or glue.

Thanks for the Tesa tip - I am just ordering some

Dave, what do you after HT to surface finish your monosteel knives?

Matus said:

Dave, what do you after HT to surface finish your monosteel knives?

Click to expand...

All belts.

Dave Martell said:

All belts.

Click to expand...

What types and grits?

Dave Martell said:

All belts.

Click to expand...

Matus said:

What types and grits?

Click to expand...

On every knife....

Norton Blaze 36, 60, 80, 120
Trizact Gator A300, A160, A100, A65


Then I move onto Scothbrite belts and depending on what steel is used I have a different line-up. I use buffing compounds on all these belts too. How you use these belts (pressure/belt speed/amount of compound applied) is a HUGE factor in the final finish. This part is a bit too difficult to explain in detail.

Thank you Dave, seems I am in the right ballpark. As much as I would love to push you into 1000 word explanation (I love the details), I do realise that that would be too soon for me to make use of it (we have a saying in Slovakia that say that "It does not make sense to feed pearls to pigs" - that kind of describes my situation ). I may come back to you once I can actually grind a decent bevel on a belt grinder - that will probably take a while (all those long weekends we have coming are filled with family activities leaving little to no time for some serious "studying"

Let's see a WIP. I know you can take good photos:doublethumbsup:

This happened to me while refinishing my knife. I just taped off the side I had finished and refinished the scratched side. Works in a pinch, tape residue be damned.

jessf said:

Let's see a WIP. I know you can take good photos:doublethumbsup:

Click to expand...

I will do that, just did not get to knifemaking past few days. The blade is on my magnetic rack waiting to get some sections touched-up to get back the profile I wanted (should be minor work). I will then go back to final finish. The rhinospeed sanding paper arrived already, so I am good to go once the time allows (probably next week because of some family business going on over the weekend)