Sand paper

Re: Sand paper

Bill Tindall, E.Tn.

See my Article in the Articles section on this topic.

I got glass in 12 x 12 pieces and fastened 3" strips or each grit, 4 to a side.

There are several keys to making this technique work well- proper abrasive selection, small steps in the abrasive sequence, pull don't push.

Properly employed the abrasive lasts for dozens of sharpenings and goes quickly, just a few strokes per grit.

Re: Sand paper

David Weaver

80 and 220 are the only two you'll ever need for everything.

I disagree with this recommendation

Bill Tindall, E.Tn.

If people tried the proper abrasive composition and particle sizes this technique would be more popular. Easily crushed silicon carbide used in larger particle sizes leads to short abrasive life. Abrasive companies recommend skipping at most one mesh size when abrading wood or metal. By stepping down particle size in small increments only a few strokes of metal on abrasive is required before moving on to the next size. The benefit is rapid edge preparation and long abrasive life. A 3 x 12" strip of abrasive will last dozens of sharpenings. I have a strip of 80 grit zirconia paper I have used (occasionally) for years.

The only disadvantage of using abrasive sheets is the necessity of using a jig to maintain the tool angle across the series of abrasive sizes.

As an alternative to PSA paper one can use spritz of 3M "repositional contact adhesive" on the back of uncoated paper.

zirconia and ceramic...

David Weaver

are only useful if you're willing to use high speed and low pressure or go slow.

Trust me on this one. I've prepared hundreds of irons and probably flattened more than 100 planes.

Tough al-ox paper is what's needed, this is only for prep - not upkeep. I've tried zirconia (blue, purple), ceramic (pink) and various al-ox, and silicon carbide.

Crude aluminum oxide paper in two grits is the most practical. When the 80 grit is worn in a little bit, a skip to 1000 grit stone on the back of a tool is fine. Cost per foot is about 50 cents on 4"x10 yard roll PSA and the abrasive is designed to stick fast.

(I have also filed, scraped, used loose silicon carbide, loose alumina and loose diamond)

Advice for high speed or powered grinding doesn't work for hand grinding. Expanding away from that to what I advocate will free someone up to work quickly and start making or adjusting more tools, and the lap doubles with ability to tune miters (if one would want), flatten tools, etc.

On the belt grinder above about 3000 sfpm, the higher tech abrasives start to make sense, but not under heavy hand work. Ceramic belts are almost magical at 5000 feet a minute, but they need speed, and then they need certain pressure to be fractured properly.

220 grit will prep most reasonable shape tools quickly, 80 grit will start others.

Separate Comment

David Weaver

I didn't really get much re: the specialty abrasives until recently getting a high speed belt. I figured something would be different at speed, but until getting hands on, I wouldn't have guessed the huge difference in performance that flip flops with speed.

For example, all of the abrasives, no matter what, break down fairly quickly. For heavy hand pressure, what you really want is a 1-2 combination of things that work well when partially broken in but that are tough. Plain non-fragmenting alumina meets this. 80 grit is a little brisk at first, but as it settles in, it works very well. 220 seems great at first, but once settled in, it's a little slow (but still a great set up for a stone).

Fracturing abrasives like pressure sensitive ceramics and silicon carbide break down very fast unless light pressure is used, but that's not generally what you want by hand. There's more accuracy with higher pressure and fewer strokes. They last less long than actual alumina and don't work faster because they go too fine too fast.

Flip things around on a belt grinder and the inexpensive aluminum oxide abrasives work OK, but generate a whole lot of heat. The ceramics that break down under hand pressure come into their own, and the particles that they remove are much larger, especially in annealed material, and in hardened material, they grind so cool that you can add bevels to a chisel after quench and temperature and not threaten tempering.

This kind of thing is poorly advised where there's no industrial precedent. There's none that I can think of for heavy hand grinding, which is what the first step is on any tool that's not flat enough to go directly from stones. Experience is king, and laziness combined with repetition (repetitive work is where laziness really flourishes due to the drive to do it faster and faster with less effort) beats textbook advice.

Several tasks mentioned

Bill Tindall, E.Tn.

For bevels I am going to stick with the recommendations I made in the Article. It is fast and the result if carried through to the end as good as it gets in my hands.

For plane bottoms I don't disagree with 80 grit stuck to something flat. A busted belt stuck with repositional contact adhesive will mow off cast iron at a breathtaking rate and if done without the care needed result in a plane bottom that will need a trip to the surface grinder to salvage. I have a mile of 80grit I bought for $3 a pound at Klingspore. Provide postage and I will send a lifetime supply.

Driven by a motor I am not dissuaded from the recommendation of zirconia abrasive. Maybe with easily ground steel ALOX is fine but with 3V it was slow and not long lasting compared to the blue stuff. I keep a blue belt on my 6 x 48 belt sander.

For plane blade backs what is best is to order plane blades from Lee Valley and not need to flatten them.

Any chisel pit removal or flattening I have done by hand power has gone so slowly I have decided I will avoid ever buying something that needs it.

Re: Several tasks mentioned

David Weaver

Bill, a couple of things:

* this question was about hand lapping. Blue zirconia is wasted there.

* you don't want to use salvage belts on a lap - you can't get it flat enough or secure enough to a surface with reasonable effort. You want (not you, but others) PSA roll. The grits I mentioned (80 grit for a plane bottom is fine and the smartness of the grooves can be knocked off with hand sanding using 180 or 220 grit as long as the lines go with the direction of the plane)

* the same psa rolls are ideal for hand grinding the back of an iron.

As you mention small pits being a problem, it's because of what you're using. I don't choose badly pitted irons for a different reason - by the time you remove the metal from the back, you're changing the shape of the iron.

But it takes me a matter of a couple of minutes to prep a subpar plane iron and to set up a vintage plane iron that was never flat in the first place, probably not more than 5-10 minutes on average. I prepped a mexico stanley iron in a couple of minutes on a video last week. It wasn't selected, it was just random out of a box.

What's recommended on a power sander and what's recommended on a lap as joe asked about are vastly different - that was my point. All of the tech docs in the world won't help with this as it's not something done industrially.

This run of paper is also good for primary grinding for someone who doesn't want to have a grinder.

3V for a plane iron wouldn't be my choice because the vanadium carbides don't offer appropriate gain in woodworking - they resist common abrasives but don't outperform chromium as far as wear resistance goes (as seen by matching 3V with AEB-L and bettering it with XHP). But I don't use any of that stuff on a regular basis - AEB-L has potential. This is different when you use hand tools for dimensioning - something that grinds slowly and holds its wire edge hard is intolerable.

The setup I'm talking about pays off for just about everything - old moulding planes, chisels, used plane irons, setting up the undercut on a cap iron -all of it is done at great speed and it's no longer an obstacle.

by the way, the reason I'm familiar with using..

David Weaver

...red belts on a glass surface is because the very first pile of coarse sandpaper that I got was one blue belt and a whole bunch of red belt scraps in the same kind of thing you're talking about - klingspor 20 pound box.

The virtue of the PSA paper is it sticks, it stays totally stuck to a surface and then can be removed with an old chisel bevel up - quickly, and cleanly chiseling the old goo off of the glass for a very clean surface.

I'm not sure what article you're talking about, but Joe is asking a very specific question that I've got a lot of experience with. I'd like to see him have success with what he's doing, thus the persistence.

Re: by the way, the reason I'm familiar with using

Joe in a Cleveland suburb

Thanks guys for the feedback.

I found Dura Gold Premium 220 and 80 grits on Amazon. Cheap per roll.

It is coated aluminum oxide corundum.

David, is this the type of paper you are talking about?

Thank you.

yes

David Weaver

most of what I've gotten is either white, gray or gold.

(which is good, you'll be able to see it contrast against the swarf to see how fast it's still working).

disagree

Bill Tindall, E.Tn.

you don't want to use salvage belts on a lap - you can't get it flat enough or secure enough to a surface with reasonable effort.

PSA paper is simply a paper backed abrasive with contact adhesive coated on it. Easily replicated from properly selected paper or cloth backed abrasive and a spray can of contact adhesive. Why make you own? Klingsor's version is more costly than making your own. You may want to stick something you already have to a flat or curved surface in the shop. If you can buy PSA that you desire at an acceptable price....agree that is the way to go.

Any abrasive with a flexible backing can be stuck flat on a table saw, jointer bed or piece of glass with 3M repositionable spray can adhesive. Spray it on the back of the abrasive, let the solvent flash and stick. Its advantage is that it does not stick as tenaciously as some PSA backed paper. I agree that the red stuff from Klingspor is backed with a material so stiff it may not stick flat. However, the gold or green abrasive is so limp it will conform to any surface, flat or curved. Ditto on paper. Choose a paper with a stiff backing and it may not stick flat.

I create all sorts of sanding shapes by sticking the limp cloth backed abrasive to cans of various diameter, dowel rods, jointer bed, piece of glass. I dumpster dive the bins at the Klingspor store in NC to secure a variety of grit sizes 80 to 400 then convert it to PSA as needed.

I've been through all of these options..

David Weaver

contact adhesive isn't as handy as the rolls. None of these things matter much if an iron is just having its bevel ground.

The adhesive on the rolls is just better - it's instantly available when you apply it, and comes off cleanly with a chisel "cutting" the paper off of glass. The paper rolls do better with absolute flatness vs. scrap.

I'm not sure what klingspor's box costs now, but I believe it's closer to $40, and you get a grab bag of stuff. My last box (I've gotten two) had less useful coarse paper in it and more mid grade paper.

Back to the PSA rolls - I like 4" by 10 yards. If you buy intermittently and at whatever the price, they're often about $20. From time to time, amazon will run something around $10-$12 a roll for quality paper (it won't be mirka, but it may be porter cable branded, for example). When that stuff is $12 a roll, an application 3 feet long is $1.20. It's enough better than belts to forgo the contact adhesive (and you don't need the contact adhesive - the paper has the adhesive only where you want it).

The paper rolls tend to have better action than the cloth paper (which seems to be more geared toward anti-clogging) - I don't know why that is, and 80 grit settles into "slow" 80 grit and is useful for a long time just cleaning off swarf. Stearated and other "filled" belts seem to go really dull quickly.

We're discussing a difference potentially in pennies here to use something that works better and you just roll out and stick down without wait.

Before I could bring my cheap self to buy PSA rolls, I did all sheets, belts, etc, with 3m spray adhesive (i tried water, etc, all of that stuff). If it worked nearly as well, I'd still be doing it.

(i'm not so cheap that I don't just pay $16 a roll or whatever it takes for a new PSA roll when I run low, but if I have one roll on hand and amazon runs a $12 roll under my nose, I'll buy. I'll save the klingspor box for abuse use and to give to the kids.

It is possible to use it - it's possible to use anything. I've flattened several chisels recently on an out of flat medium crystolon and india stone when I didn't want to get stuff off the bench to use the paper lap - but the way I'm suggesting is better. I think this is a case where I have more experience than anyone on here (both in items tried and certainly in sweat and effort perception) and it's better to take advantage of it.

(the reason that I like the 4" rolls is related to planes -I'm sure the 2 3/4" size that's more common and usually cheaper per linear foot is fine for everything else - and it would be fine for planes).