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  1. #16
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    Quote Originally Posted by tony_A View Post
    .....Is there any science that goes into deciding what skew angle to use?.....
    Possibly, Tony, but I didn't use any science.

    My method was to do a bit of reading, but the closest I could get to a specified angle was "about 10 degrees", so that's what mine is. I don't think it's super-critical, you want enough of an angle to have an effect, without reducing your width of cut to a ridiculous degree. My total experience before this plane was making two other skewed planes, the 'pseudo badger', and a 1/2" shoulder plane. [Edit: No, three, I forgot about my dovetail plane]. What I learnt from those was that it doesn't take much skewing of the blade to have a very noticeable effect on the cut, particularly at the low blade angle of a SP. The SP I made has 1/8" thick sides and a 1/4" core, which means the blade bed inside the walls is barely wider than the tang itself, giving very little room for lateral adjustment. The smallest error in blade angle seems to be amplified at a low bed angle, so it took some fussing to get the blade ground & sharpened close enough to the correct angle. I had to get it near-perfect to be able to set it up for an even cut.

    It wasn't such an ordeal with the bevel-down planes, I've got more room for lateral adjustment so the blade angle could be off by a degree or more & there would still plenty of room to cant the blade enough to correct it. I do try to get any blade 'right', but being a hand sharpener, my blades can take on a bit of a slew after multiple honings - I seem to lean on the right side more, even when I consciously try to counteract it. It only amounts to a fraction of a degree between re-grinds, but it's very noticeable on my Bailey planes. I start off with a freshly-ground & sharpened blade with the lateral adjuster more or less in 'neutral' but sometimes end up with it way over to one side by the time the blade needs to re-visit the grinder....

    If anyone has any relevant info on skew angles that does entail a bit of "science", or any comments/observations, I'd certainly be interested to hear about it....

    Cheers,
    IW

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  3. #17
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    Thanks for another informative thread Ian.

    I was just thinking about accuracy when peening and wondered if using a round headed punch would help. The punch could be located accurately before striking it. A second hammer could even be used instead of a punch. Perhaps you could try this out on your next plane build () and let us know how it goes.
    Cheers, Bob the labrat

    Measure once and.... the phone rings!

  4. #18
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    Tried it many years ago, Bob. There have been a few discussions about how best to close up dovetails here & on other forums. Using punches works, and some folks favour that method, but there is a major problem, imo, in that you need three hands to make it work well. I hold the job in my left hand and move it so there is always a solid bed under where I'm striking. I also frequently turn it so I can see different aspects and hit from different angles as required to move metal in the direction it needs to go. To use a punch, you would need to secure the plane to your anvil. Then you'd have to either constantly unsecure & change its position, or set it up so you can move around & attack it from all sides. That doesn't suit me 'cos I like to sit down & get comfy; beating-up a big plane like this one can take a while!

    So yes, by all means try using a punch if it seems more manageable to you. The punch will need a bit of attention on the grinder to produce a rounded end, not a sharp-edged end like a nail punch. I recently saw a plane someone 'peened' with a sharp-edged punch and it looked pretty mankey, & left a lot of voids, judging by the 'done' pics.

    I may have over-stated the case a bit, I certainly don't want to put anyone off trying! Learning to peen accurately isn't all that difficult, really. By the end of your first real job I predict you'll be pretty good at it. Normally, my dings are infrequent and not too severe these days, I guess I was just having a bit of an off day when I did those rivets. I was also wearing an ambulatory blood-pressure monitor on my left arm, which made it awkward to flex it properly. A sensible person would have waited and done something else for the day, but being sensible has never been one of my vices.....

    Cheers,
    IW

  5. #19
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    Apart from liking the look of brass I knew very little about the metal and wanting to have a go at this plane thingy that Ian has inspired, I did a little research.

    Brass is primarily an alloy of copper and zinc (bronze is an alloy of copper and tin) with at times other trace metals including lead and aluminium. The more ductile, and consequently malleable, brass has a higher content of copper and less of zinc.


    Ian’s H62 has a copper content in a range around 62% (not surprisingly) while H59 is lower in copper. These “H” designations seem to come from China with a slightly different nomenclature used in the Western world where the numbers appear to reflect more on the zinc content but not exactly.


    The softer malleable alloys are the Alpha brasses, the medium brasses, more suited to hot working, are the alpha beta brasses and the harder, corrosion resistant material is the beta brass, which includes the naval alloys favoured for marine use and includes admiralty brass used in the condensers for turbines.
    Copper content may be as low as 50% in this last category.

    Some information here:

    https://www.thebalance.com/brass-types-3959219

    A quick glance around Ebay showed that H62 was not commonly available, but H59 (presumably a little harder and less ductile) was more plentiful. From Australian suppliers C385 was the ubiquitous alloy.

    Regards
    Paul
    Bushmiller;

    "Power tends to corrupt. Absolute power corrupts, absolutely!"

  6. #20
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    Paul, caution! Researching brass will do your head in! :oo:

    There are at least FIVE (six if you count the apparent double system the Germans use) different standards in use. The "H" system does indeed come from China and the number corresponds with the % copper content, which is a bit more logical than the American system, whose numbers bear no relation to the proportions of either Cu or Zn!

    Note the table linked to doesn't go as far as C385, but the bloke at the place where I buy my brass tells me 380 & 385 are very close. I have had some 380 & I didn't notice any difference, but I've had some bar stock from which a long continuous spiral of swarf spun off the tool instead of the chips you get off 385. No idea what that was, but it sure was nice to turn & thread on my mini-lathe. My reading tells me that the chipping is exactly what 385 is designed to do, because the little chips are far easier to suck away from automatic lathes cranking out zillions of parts without pause. It's that little dose of lead it contains that makes the difference, which seems counter-intuitive, since lead is so soft.

    The rule of thumb I was given half a lifetime ago was that the more copper & less zinc, the more ductile the alloy. This seems to be true generally, but it doesn't always seem to be a simple relationship. The H62 as you pointed out, is 62% copper, which is only a little more than the 385, but they look different (H62 is more coppery-coloured) and most certainly behave differently under the hammer. This pic I posted above tells the story at a glance. Two slivers about the same thickness that I hammered - the 385 is splitting to bits at about twice its width, the H62 has gone well past that & shows no sign of giving up: 13 C385 vs H62 b.jpg

    The difference is presumably all due to the ~3% lead 385 contains?? We had a tiny bit of metallurgy in my first-year chemistry course, & while I remember terms like "eutectic point" etc., I have only a vague memory of what they all mean & none whatever of the science behind it all. It was more than 50 years ago now, so I reckon I'm entitled to forget a bit of it.... :;

    Metallurgy is a dark art/science as far as I'm concerned, so I rely on the empirical approach - whack it & see. As far as plane-making is concerned, while it would be nice to make your first plane with a more forgiving brass, you are unlikely to have trouble with the 385 if you limit the amount of peening to be done on it. This is quite easy, as it happens, because the typical way we cut the dovetails (i.e., 'tails' on sides 'pins' on sole) means we can fit the brass tails closely in their sockets. Most of the metal-moving required is done with the steel, and only a little pounding of the brass is required to ensure it fills the sockets tightly. Both mild steel (& the gauge-plate I prefer to use), will take a LOT of peening without protest (though they put up more resistance than the brass).

    Using a softer (& more malleable) brass would allow you to be a bit sloppier with the initial fit of your D/Ts, because you can spread it more to fill any big gaps. But you'll pay a price if you're sloppy with your hammering, 'cos any dings where you don't want them will be deeper & harder to remove when cleaning up (damhik!).

    So to boil all that verbiage down, I say don't worry too much about which brass alloy you use unless you want to make both parts of your dovetails in brass. About the only time you will need to do that in plane-making is adding front or rear pieces that you want to look continuous with the sides, as with chariot & mitre planes, for e.g., & in that case, I wouldn't recommend attempting it with 385. (I did, once, & the result was very fugly. Now I'm a bit more experienced I might get away with it, but it's not worth the effort & angst.)

    The best advice I can give is to take lots of care cutting & fitting your dovetails, then the peening is a walk in the park. Take as long as it takes - it's one of those jobs you can work at whenever the mood strikes - as amateurs we don't have some big intimidating shop manager standing over us..... :U

    Cheers,
    IW

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