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Looking for finishing / sanding efficiency tips


AlexDB

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Hello!

I'm semi-new to the knife making world. I've made a small handful of knives in a few different ways. I've forged a few, filed / did a few with no equipment, and a few with an angle grinder. I currently do not have access to any form of belt grinder (with a slack belt), but do have a standard bench grinder.

My main problem I'm having is finishing the steel, with an emphasis on sanding. I feel like if I want to get any any sort of decent finish on a piece, I end up spending 10+ hours sanding. I'm looking for ways to not spend that much time with sand paper. I don't mind the overall process being long, but when sanding takes longer than making the rest of the blade in some cases, I feel like I'm wasting time that could be spent honing my skills on the actual knife making process. I typically work in O1 or 1095 right now. I feel like I should also say that I change sandpaper liberally and keep it lubricated during use.

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My Question:
So I'm looking for suggestions on what people think would be best to speed up the ending processes. I've got some funds, and am considering where to spend them., but am wondering what other makers here think. While always worth it, should I grab some finer files and hope transitioning to them from the harsher ones will speed up initial sanding? Or will the different be too subtle? I was thinking of getting a cheap belt sander just for lower grit sanding passes (and not stock removal)? I know a nice belt grinder is always the best, but I'm not sure if I'm ready to spend over $500 on a grizzly or any of the really high end ones. And I'm not sure if I trust my fabrication skills to build one myself.

I could also just rely on an angle grinder for low grits, but I don't really trust it for flatness.

Any suggestions help!
Thanks

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On a flat grind, I used a fine-ish oil stone loaded with synthetic 5w-30 to go from draw filed to 600 grit sand paper.

I also noticed I got a finer finish using a 6" single cut bastard as opposed to the 10." I'm doing everything by hand, so even that difference seems significant.

I'm fairly new at this, too, so if anyone else wants to chime in, go with what they say.

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A file card (a metal brush used to clean out files) could help reduce gouging from chips that get stuck in files. Getting some finer files would be a good idea. As far was sanding here are the things that helped me: use a rigid sanding block (for me, a piece of 1/8" mild steel), have a solid way to hold knives while working on them, use a lubricant (I like windex), and get some good sand paper (my favorite is rhynowet redline). I also find I can put the most "power" into sanding when I'm standing and pushing the sanding block pretty much straight away from me. Hope this helps!

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I have a cheap 1x30 belt sander, you can make a stock removal blade with it but it's easy to stall the motor. The sander will allow you to do a nice machine finish which is fairly easy if you are steady with the sander.

I started forging my blades closer to finished, that's the fastest way to shape steel I think, then I started filing blades with thinner edges before heat treating them so I have to work less hardened steel. Hard steel is hard, hard on tools, and hard on time. soft steel is hard too, which is why I like to forge closer to finished.

I have read that if you aren't cracking some of your blades in the quench you aren't making the edge thin enough. 

Some people will say to leave the edge the thickness of a dime before heat treating, but I think the  optimal edge thickness depends on the thickness of the spine and how the knife is being heat treated. I have quenched miniature knives with a spine thickness of 1/16" or slightly more and nearly sharp on the edge into canola oil without them cracking. I believe that a blade that is only edge hardened NOT WITH CLAY But only the edge heated to critical and the whole blade quenched does not need as thick of an edge as a fully hardened blade. 

So the best advice I can give is remove as much material as you safely can before heat treating the blade, it's different for every blade.

i think smaller files are supposed to be finer while larger ones are more aggressive, get good quality files if you can and learn how to use them, learn good grinding technique too, you will get better work done faster. Sometimes I use a filing jig for stock removal blades, they are wonderful, some people might look down on them but I know they can save time for a beginner.

start sanding with a low grit sandpaper, 80 grit doesn't seem to remove much material to me but the lower the grit the harder it is to remove the scratches with the next grit. Sandpaper grit progression and the backer you use are also very very important, I use steel backers to flatten or wood backers to blend. Think of the wood as sort of a slack belt on a grinder, not nearly as slack but slack enough to blur a grind line.

change the direction you sand with each new grit, that lets you see the remaining scratches from the last grit. 

 

I think that's enough from me, maybe I should write a book so people will call me a fool and I'll know when to stop!

good luck! That last bit of grinding a hardened blade is my least favorite part.

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I have much the same issue as you, angle grinder, 4x36 bench grinder, amd not a whole lot else. My method is to remove all scale with the angle grinder, then i give it a general smoothing with a low grit flapper wheel. 

Invest in good sanding belts, the belt type definitely makes a difference. Also, having several grits of belts makes hand sanding go a lot faster...

Then in my opinion, just get every possible grit of wet/dry sandpaper you can get and go nuts... I'm still working on making things go faster, but just in the few months that ive been workin religiously, ive cut my sanding time in half just from general practicing and getting better at stuff... So dont give up, just throw some more determination at it lol.

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Finer files are a good way to go.  My usual process before I got a belt grinder (and sometimes even now when I want to do un "unplugged" blade) is as follows:

1. Forge as close to finished as possible. 
Take your time to make sure everything is as good as you can get it.  Normalize three times.

2. Remove scale.  This can be done with an angle grinder, an overnight soak in vinegar, a few hours in muriatic acid, or by vigorously rubbing with a broken grinding wheel (no joke!).  Even a combination of all the above.

3. Profile the blade with an angle grinder or the biggest file you can find. I use a 14" mill bastard,  Simmonds nu-cut, or a Nicholson Magicut for this.

4. Drawfile using the biggest file you have, then drop to the next size down.  File teeth get finer the smaller the file, as in the 14" mill bastard is far coarser than a 6" mill bastard.  I start with the 14" files, then drop to a 10", then a 6," all mill bastards.  Then I go to a 6" mill 2nd cut, which is twice as fine as a bastard cut.  Then I go to a 6" mill smooth.  Just like with sandpaper, you'll spend more time at the coarser cuts to get everything flat and even.  Once you've establish the flats, it goes really fast. 

As long as you take great care to keep the teeth clean by carding often, by the time you get finished with the 6" smooth file you're at about a 180 grit finish.  Ten minutes with 220, ten minutes with 400, and you've got a nice clean satin finish ready for heat treatment.  If you use anti-scale compound during heat treatment, you can jump right back to 400 grit paper and be done.

On a bowie-sized knife the process after forging and scale removal is complete takes me anywhere from two to six hours, depending on the usual variables.

Some people use EDM stones instead of files.  I haven't had good luck with them, which means I probably don't have the right brand.  And like Aiden and everybody else who has tried it, I find the Rynowet paper to be far superior to the black wet-or-dry from the auto parts store.  Norton black ice was great, but I don't think they still make it.

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Thanks for all the feedback guys!

I didn't realize that shorter files of the same cut are often less harsh as well. I think what I'm going to start with is just invest in some more files of various lengths and cuts and see what good that does me. I have a few, but they're all bastard cut files. I have a filing jig I made as well, but that's more of a stock removal thing I guess. 

I usually just get sandpaper from a local hardware store, but I'll look into trying another brand (such as Rynowet).

I have kind of a dinky file card. Is it worth the extra $10 or so to get a really nice one? Or is are the extra bucks for more of a longevity thing?

I also think I'll spend some time optimizing my overall technique. For filing a forged blade, what type of clamp setup do you guys use? 

Thanks again

Edited by AlexDB
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Hi Alex

Attached is a picture of the filing fixture I use for profiling blades before going into final sharpening and heating treating

the file is bolted to a long rod that passes thru an eyebolt so I can adjust the height and angle of the file as I work

18216647_413044115747839_8890168887151820965_o.jpg

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I use one of those toothbrush-sized wire brushes.  For those chips (pins is the correct term) that won't come out with the brush, turn it over and use the wooden back.  For the pins that REALLY won't come out, I use an exacto knife blade and pop them right out.

For clamping there are some really nice blade vises available, but I just put a board in a bench vise and c-clamp the blade to that.

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I stick a board in my vice and clamp the tang onto the blade, If the tang is tapered I support it with a wooden wedge. Same goes for the blade. The blade will move with just one clamp and two clamps get in the way so I put a nail in the board that the blade sits against to keep it still.

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one thing that helps me a lot is filing straight off the blade rather than an angle, and i do the same with sanding so i get straight lines. i only sand to 220 and I'm happy with the finish i get.

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I think for what you re trying to do. Alan's method is probably best.
You can get needle files that are so fine as to be like 400 grit paper.
You have to learn to file.
Files only cut on the push or as a draw.
Pulling back will ruin your files.
Also once you have a pre hardening finish you will have to deal with decarb after hardening.
Which is hard to sand out.
I would suggest getting anti scale.
Wipe the blade with amonia and then paint with the anti scale from brownels and the blade should come out as clean as it went in.

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