Milling tolerances
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What are acceptable tolerances when milling a board to 4 square? when checking for flat in both directions with a straight edge their will always be some small amount of light in a few spots but small spots and usually less than a mill. I do always make sure any area involving a four sided knife wall for a tenon is always dead square to ensure a perfect meeting up of the knife wall on all four sides. Any thoughts on this?
I think you should aim for very high standards, don’t forget to check for twist as well as squareness, very important on doors with panels in them, I try to aim for twist free wood as well as square on everything I make.
I spend a good while preparing the wood, it is always worth it. I make sure the ends are always square as well and usually shoot them with the shooting board, it makes things a lot easier later on and gives you more confidence, well worth the extra work.
Personally I don’t think gaps on a garden gate are acceptable, just aim for high standards on everything you make and you can’t go wrong, the standards are set by you and no-one else, you set your own standards, so it is your choice. Take your time and don’t rush anything, it will improve accuracy and lower the chances of mistakes, but also accept that mistakes are going to happen.
“Looks good, is good.” That’s an often repeated saying of Charles Neil. The point is that, as you move away from rectilinear pieces, and start making things with more form, like Paul’s current desk, Queen Anne, and a million other examples, you will be changing the shape of work and doing so is often imprecise. One thing I’ve learned from chip carving is that curves and lack of regularity is an opportunity to put (aesthetic/artistic) movement into a piece. Some of that is worked out during the shaping, and you won’t make all the parts exactly the same no matter how much you try. Cabriole legs will have variations, leg to leg, but because of the separation between them, you don’t notice. So, think about why you need the piece to be perfectly 4-square. You may actually need it to be perfect for joinery reasons. Or, you may only need certain sections to be perfect, and others will be shaped anyway. One thing I don’t like about machine-made furniture is that it is often just rectilinear, blocky, tinker-toy forms because it was cut with fences. Machines can produce more than that, but that’s what many amateur (and professional) wood machinists make. If you do the same with hand tools, I think you are missing an opportunity to take advantage of the hand work. This is just my aesthetic taste more than a matter of right and wrong.
To answer the question, I aim for no light. I won’t let noncritical portions (between joints) risk joinery sections, though. I require more of my reference face and reference edge than other faces/edges. I know that finishing will close or hide some joinery gaps and also know that fiddling with things can make them worse, so there’s sometimes a gut feeling of “leave it, move on.” I hope it happens less as I get more experience.
11 September 2017 at 11:10 pm #315840After years of trying and now watching Paul’s videos, I’ve found it fairly easy to work to a strict standard. The key, I think, is patience and paying attention to everything you’re doing. With really sharp and well-tuned hand planes, I’ve found it’s not a big problem getting boards to square. That said, I have seen my dimensioned pieces bow or twist slightly a day or two after planing them. So now I just do an initial planing, let them acclimate in the shop for a few days, then do the final planing, which involves the removal of very small amounts of wood. I also use a marking gauge when thicknessing boards. On occasion, I use a cheap plastic caliper with a vernier scale to check parallelism of the two faces. My old thickness planer, long since sold away, wasn’t as accurate as I can be with handplanes.
12 September 2017 at 2:54 am #315848i do a tap test on my bench, sometimes on a big mirror i have as well.i like to have that first face perfect before i put it through the planer..
12 September 2017 at 4:26 am #315853In one of his books, Jim Toplin recalled some profound advise from a boat builder.
No one looks at both sides of a boat at the same time.
6 October 2017 at 10:30 pm #330013I’m just curious, do folks here use the beveling technique to prevent spelching and to help in thickness a board? After flattening one face, then marking out the final thickness on the edges, you just plane a bevel right to the thickness mark. I’ve been using it, putting on the bevels with a block plane, and found it’s a good way to go.
I’m just curious, do folks here use the beveling technique to prevent spelching and to help in thickness a board? After flattening one face, then marking out the final thickness on the edges, you just plane a bevel right to the thickness mark. I’ve been using it, putting on the bevels with a block plane, and found it’s a good way to go.
For spelching prevention, always, for thicknessing aid, generally only as the boards get larger (obv that’s a very subjective thing…say over 4 feet long with good width…10 inches or more. I saw a video a year or two ago by The Renaissance Woodworker where he demonstrates the concept, found it very helpful.
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