Sandpaper grit chart uk4/23/2024 But speaking for myself with a film finish I can't tell them apart because I'm feeling finish, not wood, and there's no textural difference to transmit through that. But as soon as the first coat of finish goes on most or all of that difference vanishes (and the more coats of finish go on the smaller any difference should become).Īs for a tactile difference, that's harder to argue one way or the other of course. In the naked wood it can be extremely easy to see the difference between a planed surface and one finished by sanding, as you say it's obvious from across a room. Just to emphasise if needed: this is after finishing. Well planed > badly sanded certainly, but not over any possible quality of sanded surface. I've seen similar debates elsewhere and FWIW I've never seen good evidence presented on the planing > sanding end of the argument. With a larger diameter cutter block the scallops would be shallower.Ĭlick to expand.Not sure if you missed the threads or the individual comments, this same has been argued here a number of times in the last couple of years (not sure if it's the most recent time but it came up during one of the mammoth threads about hand planing about a year ago). With the same size cutter block these would translate into scallops from 5 to 45microns deep, with 30microns equating to 320grit, custard looks close to spot on. This seems small so perhaps the compressibilty of wood effects the outcome, or my maths is wrong.įrom what I recall scallops I have seen from my p/t seem to be more in the order of 1-3mm wide depending on feed speed. We can solve for the height based on pythagorus, height of ripple = 0.1 - sqroot(0.1^2-.0003^2) = 0.45microns - 1.8microns (30microns is 320 grit). 006s in this time the board can move forwards. The blade speed is huge in comparison to the board speed, say 40m/s (120ft/s) blade speed vs 0.05-0.1 m/s (10-20ft/min) so passes the board effectively instantaneously, however for a two cutter block rotating at 5000rpm a cutter only passes the board every 1 / 2 / (5000/60) =. Each pass of the blade takes a circular cut out of the woodwork with a radius equal to the cutter block + blade extension, assume 0.1m. The two scales are about equally linear in the 400-600 range.This is fundamentally a geometry/trigonometry question. This chart shows (Grit number * Particle diameter) for both scales:Īs we can see, there is no clear conclusion - the ISO scale is more linear for grits below 400, while the CAMI scale is more linear for grits above 600. Some extra data - I wanted to see whether the ISO scale or the CAMI scale are more linear when comparing grit number and particle diameter. Here is the same data in tabular format: Grit No You can even mix and match sandpaper from the two scales without issue. In other words, for woodworking, it does not matter which scale you use until you get to grits 360 and above. As you can see, the difference between the two scales is <25% up to 320 grit. The left axis indicates the grit diameter in um, and the right axis indicates the percentage ratio between CAMI and ISO grits. Used to polish finishes on wood and metal. Used with a belt or orbital sander to prepare wood for coats of finish. Here is a chart showing the grit size and the ration of grit sizes for numbers from 24 to 1000: This grit is used to sand finishes of flat surfaces prior to polishing. The tricky part is that the two grit numbers are not equivalent - for example, P360 is rougher than 360. “220”), while the ISO grit size is designated by the letter “P” followed by a number, e.g. The CAMI grit size is designated by a number (e.g.
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