Est. 1998 — 27 years of woodworking knowledge
Re: granite plate--just to be clear
Wiley Horne
>Hello Moses,
I didn't recommend using loose abrasive on a surface plate. I do think that using 3M's PSA-backed film abrasive is a good approach which will not harm the plate (although it's undoubtedly not an ISO900x.x-approved method). Unlike sandpaper, it's thin and hard and it sheds very, very little grit.
Not arguing with you about the 1/2" glass versus surface plate; just want to clarify my own recommendation.
Wiley
P. S. *LINK*
Wiley Horne
>Link to granite plates is below. Delivery costs under 'More Info'.
Wiley
Granite plates
Re: flattening with glass or granite
paul womack
>I think perhaps if I had piles of money laying around and wasn't sure what to do with them, I might spend $100 on a granite surface plate and then grind directly on the plate.
If you can wait for a "free delivery" offer, or pick it up yourself, granite is cheap.
However, for tuning a smoother, thick glass is fine. If you use my print-cut approach, glass is very accurate, since it is only used as a reference surface under very light (thus non-deforming) loads, unlike so-called-lapping, which tends to distort the reference surface, amogst other problems.
Here's my evolved solution to flattening plane soles, for your reading pleasure.
BugBear
Re: Bugbear's sole flattening page link *LINK*
Ted Shuck, Centennial, CO
>I think Paul forgot to put in the link to his plane sole flattening page, so I have included the link below. I strongly recommend this method of flattening as I have screwed up a few soles with the more common "lapping" method. Scraping or filing and testing against a reference surface have giving me much better results.
Re: flattening with glass or granite
Bill Collier
>Is there anyone who can say that they have successfully flattened a plane sole using the sandpaper lapping method? I have never seen it done, the results are always some degree of convexity. I suspect that the motion of the plane across the sandpaper creates higher pressure at the leading edge of the motion and therefore a tendancy to wear faster at the leading edge.
I think I have....
Dave (Arlington, VA)
>Hi Bill -
I think I have....with a #3 (at least it looks like it to me - but I don't have a reference plate or any blue). I used a process recommended - I believe (IIRC) - by David Barrett. I put down a 9"x11" sheet of 220 grit. Then I carefully pushed the plane (i.e. holding it low by the sides) back and forth for 10 strokes; then I flipped it around 180 degress and did another 10 strokes; then I flipped it 90 degrees and (still holding it low) went side-to-side for 10 strokes; then flipped it another 180 degrees and went side-to side again for 10 strokes. Then I reversed the process and went through it again until I thought the sandpaper was no longer cutting effectively at which point I stopped (after a "full" rotation) and changed the paper and kept going - until complete.
The theory - and it seemed to work for me - was that the relatively few strokes (going in any one direction) and the frequent changes of direction, and holding the plane low would tend to keep the "rocking problem" to a minimum by averaging it out. I did some some small dubbing around the edges, but that is to be expected with sandpaper.
A #3 and a 9"x11" sheet of sandpaper worked fine. I'm not sure how I'd do it if I wanted to do a larger planes. Seeems like that's involve gluing (and "ungluing") a lot of sandpaper.
Regards -
Dave
Re: flattening with glass or granite *LINK*
Wiley Horne
>Hi Bill,
The short answer is 'yes', but this is worth some discussion, because there is a lot of nuance in this topic.
Speaking only for myself, PSA-backed abrasive film on a surface plate fits well into a system for getting soles true, and maintaining them true. I use metal and wooden planes, and with wooden planes you need a fast efficient method for periodic sole truing. I use straight edges and the granite plate to do this.
Why abrasive film (3M)? People can get good results from sandpaper. But sandpaper has pile like a carpet; can furl up in front of the sole to dub the edge; and it leaves abrasive behind. PSA-backed abrasive film is hard and thin, dimensionally stable; it leaves a sharp edge on the plane front and sides--whether metal or wooden plane (a key point)--and it sheds very little.
I use a straight edge to check the condition of the sole. Always. Before any sole truing or maintenance takes place, the sole is inspected with a straight edge to find out if it is concave or convex, in length and width. If this is a first-time truing of a metal plane, then don't lap unless you know it to be concave. If it's convex, straight lapping will make things worse, so you want to use Bug's method, or the full-on machinist's method of spot and scrape. Now with maintenance of wooden planes, it'll usually only be off by a thousandth or two. So unless the sole is convex, I will just hit it a few licks on 30-micron paper, rewax, and it's trued. Now at that point, there is one other useful thing to do. I will take a card scraper, and relieve the interior portions of the sole (similar to putting the wave(s) into a Japanese plane sole), so that I'm sure that the front of the mouth is hard down on the work, and there's no incidental high spot somewhere that will throw off the contact of the mouth on the work. This relief will also tend to keep the sole in a virtual-concave situation, so that it won't roll over into convexity when you true it on the plate. Now if the wooden plane is convex, then there's nothing to do but scrape it flat, and I have used various planes and scrapers for that, depending on how convex it is.
Attached is a link to my set-up, which works for me. It's a granite surface plate, 24" long. Behind the surface plate is a long steel straightedge, which is back lit, so you can see daylight between the straight edge blade and the test surface. This system results in getting things flat, and doing it quickly, and does not allow them to become convex over time.
Wiley
Reference station