Sand WITH the grits or restart when finished on grinder?

[blandies]

When the knife is ready to be taken to the grinder for the bevels do you for example,

1. Use a 60 grit belt to grind the bevels and then hand sand the rest of the knife including bevels with 60 grit sandpaper....then move on to the next grit of belt like 120 and then hand sanding with 120 on the rest of the knife ...and so on?

or

2. Use a 60 grit belt, then 120 belt, then 240 belt, and so on grinding the bevels in and then when done with the bevels go back and start hand sanding the entire knife from scratch including the bevels with 60 grit, 120, 220, all handsanding? Wouldn't handsanding the bevels ruin the grinders work and take off steel you don't want gone? So my guess is the latter, grinding WITH the grits? (option number 1)


Because the bevels will be whatever grit the belt is when ground but the rest of the knife won't - curious as to how it should be done?

 

[Frank Niro]

Here's what I use for bevels. I start with 60 grit 3M 967F; 100 or 120 ceramic; 65, 45, 22,16 and 6 Norton. I alternate from one side to the other. I then use Rynowet 400, 600, 800, for Damascus but for stainless I continue with 1000, 1200, 1500, and 2000 for a satin finsh or before polishing. I hope this helps. Practice your grinding on some of those steal strips you can buy at the building supply or hardware store. It didn't come easy for me. Frank

 

[blandies]

Thanks for the bit of info Frank. I'm not sure how to explain clearer on what I'm trying to ask, all of this sanding process can get confusing, to me anyway.

Rather than which belt grits to use I meant do you hand sand with the belts on each grit or hand sand after all the belt work is done. For example 60>120>220 belts and then back to 60>120>220 hand sanding. Or would you do 60belt>60 hand sanding>120belt>120 hand sanding>220 belt>220 hand sanding.

 

[Stacy E. Apelt - Bladesmith]

Grinding and hand sanding are two separate procedures. You grind in the basic profile and bevels, and then go to hand sanding.

Something like this is what is normally done:
Profile and rough in the bevels at 60 grit.
Set the bevels and details at 120 grit.
Clean the bevels and details up with 220 grit.
Start hand sanding by going back to 120 grit.
Once everything is FLAT and all old scratches are out, go to 320 or 400 grit.
HT the knife
Go back to 220 grit and hand sand the entire blade to remove decarb. This also sets the edge thinness.
Go to 400 grit to get the surface smooth and flat.
Proceed up the grits to whatever point I want to stop at.

 

[blandies]

Grinding and hand sanding are two separate procedures. You grind in the basic profile and bevels, and then go to hand sanding.

Something like this is what is normally done:
Profile and rough in the bevels at 60 grit.
Set the bevels and details at 120 grit.
Clean the bevels and details up with 220 grit.
Start hand sanding by going back to 120 grit.
Once everything is FLAT and all old scratches are out, go to 320 or 400 grit.
HT the knife
Go back to 220 grit and hand sand the entire blade to remove decarb. This also sets the edge thinness.
Go to 400 grit to get the surface smooth and flat.
Proceed up the grits to whatever point I want to stop at.

Now where you said go back to 120 grit for hand sanding, is that just for hand sanding the bevels or the entire knife? I was concerned with the bevels being around say 240 grit while the rest of the knife is still very coarse around 60. Should I hand sand the bevels from 240grit back to 60 and then go back up the grits on the entire knife? Or leave the bevels 240 and catch up on the rest of the knife excluding the bevels and then start sanding both the bevels and the rest of the knife when I'm on par with the same grits.

 

[Justin King]

There is no reason to take the bevels from a 240 grit machine finish back to 60 grit anything, unless you need to take a bunch more thickness off (in which case there is no reason it should be at 240). Catch the rest of the knife up and move on from there. You will generally find that a 220 grit machine finish is easier to rub out by hand with 120 grit paper, so sometimes it makes sense to jump back a grit when leaving the grinder, but otherwise there is little reason to go backwards in grit.
I usually go to hand sanding before HT, and oil hardening steels usually go back to the grinder afterwards to remove decarb and get the final edge thickness, but otherwise I also see little reason to go back to the grinder once hand sanding starts (in the case of oil hardening steel the only reason to hand sand before HT is because decarb seems to happen the fastest in deep scratches, you will end up with less decarb to remove after HT if you have a fairly fine finish beforehand)

 

[cbr900son]

Grinding and hand sanding are two separate procedures. You grind in the basic profile and bevels, and then go to hand sanding.

Something like this is what is normally done:
Profile and rough in the bevels at 60 grit.
Set the bevels and details at 120 grit.
Clean the bevels and details up with 220 grit.
Start hand sanding by going back to 120 grit.
Once everything is FLAT and all old scratches are out, go to 320 or 400 grit.
HT the knife
Go back to 220 grit and hand sand the entire blade to remove decarb. This also sets the edge thinness.
Go to 400 grit to get the surface smooth and flat.
Proceed up the grits to whatever point I want to stop at.

This is pretty much exactly what I do.

 

[Daniel Fairly Knives]

Make sure you always get rid of the scratches from the previous step! It seems obvious but once you have a good "base" started all the sanding after that goes quickly.

I learned from doing lapidary work that it helps to be able to identify what grit a scratch is so you can go back to that grit if one pops up.

 

[cbr900son]

Make sure you always get rid of the scratches from the previous step! It seems obvious but once you have a good "base" started all the sanding after that goes quickly.

I learned from doing lapidary work that it helps to be able to identify what grit a scratch is so you can go back to that grit if one pops up.

Sp true. those first fewer rougher grits can be a pain.

 

[Frank Niro]

Don't do any hand sanding until you have gone through ALL the belt sanding with All the sizes first.
Another thing to help is to have your blade sides cleaned up and parallel to each other before starting the bevels. Frank

 

[Stacy E. Apelt - Bladesmith]

The usual process is :
Start with a coarse grit on the belt grinder - 60 grit is a common coarse starting grit.
Profile the blade
Set the location of the bevels
Flatten the tang and blade surfaces at the ricasso ( if needed)
Go to 120 grit and do the same process, making all coarser grit scratches gone.
Go to 220 grit and repeat. The knife should now be close to what you want, but the bevels may be a little rounded or wobbly.

Now , switch to hand sanding with a flat and hard backer block, using 120 grit . Sand all surfaces again.
Go to 220 grit and repeat on all surfaces.
Go to the final pre-HT grit - usually 400 - and repeat on all surfaces. The knife should be smooth and completely shaped...with an edge thickness of .020 to .040 ( depending on size and steel type).

After HT drop back to 220 grit and just do the same process right on up the grits.

 

[woodwrkr221]

Why is it recommended to sand to 400 grit before HT if you're going to drop back to 220 grit after HT? Somehow I'm not following the logic behind dropping back in grit post HT. It just seems counter intuitive, I'm assuming I'm not picking up on something.

 

[james terrio]

Somehow I'm not following the logic behind dropping back in grit post HT.

It depends mainly on how "clean" or air-tight your HT process is, which affects how clean your blade is after quenching and tempering.

If you're shaping and quenching with an open coal or gas forge and quenching in warm oil, it would seem there's not much need going beyond 220 grit before HT because there's going to be hard, tough scale to remove afterwards anyway. However, going up to 400, even for a few passes, will quickly reveal any deep scratches and/or flaws that might be covered up by a basic 220-grit pattern. Those deep nasties could cause problems with cracking or warping later on. At the very least, they'll be a lot harder to get rid of when the blade is 58 or 60Rc!

If your blade is going to be HT'ed in a vacuum or inert-atmosphere kiln, there won't be any scale. Even well-wrapped blades in a regular kiln can come out pretty darn clean. This means you can go right up to your finish grit before HT; there will only be a very thin, easy-to-remove layer of oxide colors on the blade. You can make a few light passes with your final grit and polish or buff as desired, boom you're done. This is true for oil-quenched steels like 1084 and O1, as well as air-quenched, high-alloy steels.

To my thinking, the idea in either case is to do as much work as possible when the steel is soft. As far as dropping back one grit (not way back to 60 or 120) is just to ensure there's nothing you missed.

Unless of course the blade is very small, thin or un-evenly ground to begin with, which can lead to warping no matter what. In that case it's generally better to HT before beveling and grind it when hardened. Just keep it cool. It seems like more work, but we're talking about smaller blades, so it pretty much evens out.