Replies

1. 
   Alan | Jul 10, 2004 01:56am | #1

   Larry,

   There is definitely a difference when you use water on wet & dry sandpaper.  Water acts as a lubricant, so it lessens the abrasive effect of the paper.  It's not unusual to sand dry, and then add water: the effect is like using two different grits of paper.  To lubricate more, lessening the effective grit more, add a drop or two of liquid soap to the water.

   I use W&D sandpaper only for truing up the soles of my planes, so this may be quite wrong, but (there's always a 'but')...

   It seems to me that you begin with paper that's too fine.  If that's so, it will take you much longer to accomplish anything, you'll use up far too much expensive paper, the possibility is greater that something will go wrong, and you will eventually want to kick the dog.

   When I begin on a plane sole I start with about a 150 or 200 grit paper--dry.  I keep using that coarsest paper until all the flattening is done:  until I have a consistent scratch pattern on the entire sole and my various tests say the sole is flat.  Only then do I use finer paper.

   I think of the rest of the process as nothing more than erasing the scratches left by the last paper.  The only job for each succeeding grit of paper is to completely eliminate all the scratches of the previous paper (and putting on its own scratches over all the sole)  As above, when the previous paper's scratches are gone I don't use a finer paper, I put some soapy water on the paper and continue until I have a little finer scratch pattern.  I work that way, going to ever finer grits, until I can't stand it any longer.*  Using water greatly extends the life of the paper; as does not using fine-grit paper too soon--too fine to do heavy steel removing.

   *Of course you cannot stop when you cannot stand it any longer on your cutting edges.  You must keep going until you have a mirror-like smoothness at the edge.

   Alan (going on and on and on--again)

1. 
   larrmartin | Jul 10, 2004 08:13pm | #8

   Good advice! Seems to hit the nail on the head as to why it's been so difficult for me. I followed your advice and for one chisel back which I just couldn't get flattened I went down to 120 grit and think I finally got it properly flat.

2. 
   chairmake1 | Jul 10, 2004 03:03am | #2

   Well I usually don't go past 400 grit. I've cut a piece of mdf. about 6" wide and 44" long and paste on 1/2 sheet size starting with 100 grit. Then 220, 320, 400 and by that time I've got a SHARP tool and I go back to work. I'm not into polishing all of my tools to the nintrh...just get a great edge - quickly - and then back to producing with that tool.

   Robert

1. 
   larrmartin | Jul 10, 2004 08:16pm | #9

   I think there's a lot to what you say. I've always worked on technique to get closer and closer to what I read -- but then I sure wish I spent more time actually woodworking like you. I'm going to try to be a bit more practical minded!

3. 
   hamelech | Jul 10, 2004 05:55pm | #3

   Larry,

   I've been using grit 'n glass for quite a while, and I share many of your observations regarding the life of the sandpaper and how it 'grabs' the tool.

   I think the sharpening process does a great job in beating up the grit, so actions such as lapping and grinding dings from the edge can take three or four strips of sandpaper per grit to get the job done. Once the tool is true, it takes very little effort and materials to get a polish on the steel.

   David Charlesworth's article in FWW# 169 is excellent in itself, and all the techniques he uses for waterstones transfer to grit 'n glass. In short, the back of the chisel/iron is moved side to side and back and forth across the abrasive to encourage even wear, and prevent dishing.

   In lapping the back of a chisel or iron, I use 3M's or Norton's extended use aluminum oxide abrasive for dry grinding in grits 60-320, since I think it lasts longer than silicon carbide, though I have the same grits in SC as well. I would recommend against conventional garnet abrasives. I switch to wet silicon carbide around 320/600, and polish up to 1500; I'll sometimes go up to 2500, but I could agree that anything above 600 is more for show than for function. I do like a good shine on the tool's back, though, since it indicates a flat surface.

   For the bevel, I'll repeat the steps above, except I'll use an #8000 grit waterstone for making the micro bevel. It's been my own observations that the paper backing of the sandpaper 'gives', and creates a rounded over micro bevel. By using the waterstone, a distinct and shiny microbevel is honed at the tool's edge. FWIW, here is the link to the stone I use: http://www.japanwoodworker.com/product.asp?s=JapanWoodworker&pf_id=01.099.10&dept_id=12341

   Once the back and bevel of the tool is well established, all you need is 320 or 600 as the coursest grit when doing touch ups, which goes fairly quickly. I use a guide, and I've put index marks on my irons with a Sharpie pen that align with the guide's edge, so I can easily repeat the main angle and micro bevel.

   Cheers,

   Seth

1. 
   newtrva | Jul 10, 2004 06:08pm | #4

   What is the best method of getting the sandpaper to adhere to the glass?

1. 
   hamelech | Jul 10, 2004 06:52pm | #5

   Newtrva,

   3M spray adhesive is a great way to get paper to stick to glass. Another Knots poster recommended melted art wax, used in true 'cut-and-paste' art/newspaper layout. I'm wondering if Glu Stick is good enough.

   3M brand 45, 77 and 90 spray adhesives are commonly available at Home Depot, and your neighborhood art store probably has 3M spray photo mount. I've used 3M 77, and I've learned that you should go real easy on how much you use. If you think it's not enough, it's enough!

   Spritz a strip of sandpaper (say 3 inches by 11), and wait 15 seconds or so before sticking it down. The reason is the adhesive will dry a bit, and release from the glass a bit better. Arm yourself with two household weapons, blue glass cleaner and orange citrus cleaner. As you spray, sharpen and peel, the glass will build up with adhesive, which you'll need to regularly clean off. Sandpaper left on the glass overnight will sometime need to be scraped off with a "paint can chisel", and the residue attacked with citrus cleaner.

   I bought a 12x18 granite plate, and here you only need to roll a strip of sandpaper through a trough of water (a la wallpaper) to get it to adhere to the granite. You can use this water method on glass, but be prepared to have the paper wiggle around first before the excess water and air that is trapped under the paper is expelled as you sharpen. Then the paper will hold fast. Most silicon carbide paper is tough enough not to rip, even when wet, but wet paper on a flat surface can have a tendency to curl up. Hence, the spray adhesive method.

   Cheers,

   Seth

1. 
   larrmartin | Jul 10, 2004 08:05pm | #7

   You mentioned the granite plate you purchased. Is this type of platte special, i.e. flatter, than just a cutoff piece of kitchen counter granite?

1. 
   hamelech | Jul 10, 2004 09:10pm | #11

   Larry,

   I bought the 12x18 granite plate from Japan Woodworker, which is the only local place I found in the CA Bay Area that is reasonably close to me. I bet a machine tooling store might carry it.  I think Woodcraft carries a 9x12, but I recommend the larger 12x18 size.

    The plate is advertised as being tool room B grade, flat to within 1/ten thousandth across the whole plate.  To me, this precision is far in excess for what you need to sharpen a tool, but $60 for this grade of accuracy is still cheap.  Also, a guaranteed flat surface is great if you need to lap a plane's sole, but again, the accuracy of the granite plate exceeds the real world requirement.

   When using glass, I bought a $3 12x12x 1/4 piece from a glass shop.  This is just fine for sharpening tools.  A granite tile from the hardware store is probably good as well.  I think 12x12 or 14x14 represents a size that's big enough to have several different strips of grit along the sides and middle (promotes a more time efficient method of sharpening) but still small enough to handle and store.

   I neglected to add that I adhered 50 or 60 grit paper to the whole of one side of the glass plate, so that the plate doesn't skid on the benchtop.

   The 2000 and 2500 grit of silicon carbide was hard to find locally, but I found a paint store that carries home and automotive products.  The paper backing of sandpaper is assigned a letter (A, D, etc.) and the 2000/2500 paper (P weight?) is thick enough that I think it causes rounding, since as the edge of the tool is pressed down into the grit, the paper (and grit) creates a dip that conforms to the tool's edge as it passes down the strip.  The A weight paper of the 1500 silicon carbide sheet is comparitively thin, so it does not deform as much, and I think the tool's edge remain's more true. 

   As always, the Internet provides other retail outlets for this abrasive, but I have no recommendations.  The 2000/2500 is not terribly cheap.  I paid about $30 for each package, which were 9x 5.5. I overpaid, I know it.  Here is a quick link I found in Google; the 9x11 sheets are probably what you're after.

   http://thetoolwarehouse.net/shop/TTW261.html

   Cheers,

   Seth

2. 
   larrmartin | Jul 11, 2004 08:06pm | #13

   Many thanks!

2. 
   larrmartin | Jul 10, 2004 08:03pm | #6

   Thanks very much for your comprehensive reply.

   After going thru the sandpaper grits for flattening, I got a good polish from wet 1500 paper. For the bevel, I went through 4 diamond stone grits (gift of my six daughters for Father's Day) extra-coarse, coarse, fine, estra fine, and then for polishing I went to my Norton waterstones, 4000 ceramic and 8000. I was pleased with the results.

   I'm going to a Garrrett Hack course at Center for Furniture Craftsmanship in Maine in another 10 days, so I suppose I'll get a critique on how well (or not so well) I did.

   Again, thanks for the help.

3. 
   larrmartin | Jul 10, 2004 08:19pm | #10

   p.s. Where do you get 2500 grit paper? I've only been able to find 600 and 1500 at auto supply stores.

1. 
   mbiker1999 | Jul 11, 2004 12:05am | #12

   I've purchased 2000 grit at wallmart. Look in the automotive section.