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Post by paulchapman on Jan 14, 2009 21:24:47 GMT
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Post by mrgrimsdale on Jan 14, 2009 22:51:08 GMT
Tapered pins work OK. Can't see much difference. I think they are just trying to sell some more expensive tools!
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Post by paulchapman on Jan 14, 2009 23:58:51 GMT
I've never used them, Jacob, but it seems self-evident to me that the proper ones would be more likely to work better. Cheers  Paul |
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Post by mrgrimsdale on Jan 15, 2009 7:34:04 GMT
I have used proper draw-bore pins and the steelwork version and non of them had this offset cam design, and turning was not part of the 'drawing' process. 'Tapered drift pins' is what they were and they worked perfectly well. Under any sort of load I don't think you would have been able to turn them.
I don't find Joel's drawing too convincing either.
I wonder if it's just another attractive woodworking myth; there are a lot of them! ;D
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Post by paulchapman on Jan 15, 2009 9:00:50 GMT
Well, having read Joel's description again, he makes perfect sense to me. The way I see it, if the draw bore pin is not of the off-set design it would tend to simply enlarge the hole in the tenon without pulling the joint tight - which, of course, would totally defeat the object of off-setting the holes in the first place. If I ever get any I will go for the off-set ones. Cheers Paul |
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Post by thebloke on Jan 15, 2009 9:24:35 GMT
I think the point of these draw-bore pins is that they only work if you're prepared to drill holes in the mortise and tenon itself, something I'm very unlikely to do. I can see though that if a big job is being built (lock gates ;D) which is outside the scope of sash cramps, then this is a useful way of pulling the joint together, although I didn't realize they worked on a sort of cam arrangement
What...not taking advice any more Jacob?...things are getting back to normal then ;D - Rob
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Post by mrgrimsdale on Jan 15, 2009 10:18:22 GMT
I think the point of these draw-bore pins is that they only work if you're prepared to drill holes in the mortise and tenon itself, something I'm very unlikely to do. I can see though that if a big job is being built (lock gates ;D) which is outside the scope of sash cramps, then this is a useful way of pulling the joint together, although I didn't realize they worked on a sort of cam arrangement What...not taking advice any more Jacob?...things are getting back to normal then ;D - Rob Joiners use them for things which are difficult to cramp - the classic being staircase string to newel. I've used them on a porch which had curved brackets you couldn't get a cramp on. They would be useful if you simply don't have enough cramps but drawboring has extra value in that it helps make a tight fit of an M&T even without glue - but you can do this better anyway with pointed wooden pegs as you don't have to pull them out! They don't need a cam action; when part way in you lever the tenon further in to the mortice, when further in and tight in the hole you tap them with a hammer. The cam action is not at all necessary but it looks clever and toolies everywhere always prefer complexity to simplicity! |
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Post by paulchapman on Jan 15, 2009 10:32:44 GMT
I bet when they invented the wheel, Jacob, you went around telling everyone that it was just another, unnecessary, money-making scam ;D Cheers Paul |
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Post by jake on Jan 15, 2009 10:51:01 GMT
To be fair, he was probably also saying the same thing when people were fawning over the newfangled square brass wheel.
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dunbarhamlin
Full Member
Lutherie with Luddite Tendancies
Posts: 244
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Post by dunbarhamlin on Jan 15, 2009 10:53:57 GMT
As an archetypal toolie (almost inevitable since I'm into lutherie but don't speak Spanish with a Mexican accent) I have both Ray Iles' weird shaped and Dave Jeske's straight, and whatever the reasons, do find the former more effective. (They need less pressure, and (in my hands) are less likey to mung the hole entrance.)
Just using the wooden peg I did find myself drilling out more often (which is a pain, because then it's just pegged not drawn.)
I wouldn't look at LN's - they're more expensive, and from a toolie perspective, more ordinary than either of the others ;P
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Post by mrgrimsdale on Jan 15, 2009 10:59:15 GMT
I bet when they invented the wheel, Jacob, you went around telling everyone that it was just another, unnecessary, money-making scam ;D Cheers Paul ;D No but you can get some expensive and unnecessary variations if you want to tart up your motor or bicycle! Had another look at Joel's drawing - in fig 2 the far end of the pin is unsupported and so would tend to swing back. You'd have to push it further in to have any effect - just like a concentric taper in fact. If you really want a cam effect a better design would be a simple oval section throughout but with a pointy end. If you think about it it's obvious. |
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Post by engineerone on Jan 15, 2009 11:00:05 GMT
it is intregueing that you cannot see the dichotomy of most of your complaints jacob. you say that tapered pins have no value, then you destroy your argument by saying that you lever the joint together  the value of the individually tapered sides is that the pressure on the whole joint is gentle and pulls the joint together without stressing the whole thing. once again a triumph of ignorance over logic ;D paul |
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Post by mrgrimsdale on Jan 15, 2009 11:04:10 GMT
it is intregueing that you cannot see the dichotomy of most of your complaints jacob. you say that tapered pins have no value, No I don't ;D What I'm doubting is the value of the offset taper as distinct from the concentric one. |
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Post by paulchapman on Jan 15, 2009 11:04:14 GMT
I have both Ray Iles' weird shaped and Dave Jeske's straight, and whatever the reasons, do find the former more effective. That's useful to know, Steve. At least you have both types and have been able to make a direct comparison. Cheers Paul |
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Post by engineerone on Jan 15, 2009 12:13:36 GMT
from an engineering viewpoint jacob, you are talking tripe. study things like marine connecting rods which are joined by tapered keys. these are only tapered on one side to ensure that the joint is drawn together in a gentle, and yet strong way. if you put the "flat side" of the iles pin against the inside side of the mortice, and that will pull the tenon in with less stress than the concentric ones, because it is doing it on a supported basis where as the concentric ones are not. paul |
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Post by mrgrimsdale on Jan 15, 2009 12:55:32 GMT
from an engineering viewpoint jacob, you are talking tripe. How would you know? ;D ;DThere isn't a flat side. It's an 'oblique cone' apparently. What is not clear is why this is different from a concentric cone. Except you can probably charge more for it! In steel erecting the tool universally used is the ' podger' which is conical. May be offset by accident as they tend to get hammered and bent. No resemblance to that little cam gadget on the Ray Isles page. |
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Post by engineerone on Jan 15, 2009 13:16:30 GMT
of course there is a "flat" side jacob, that is the essence of this type of design  the pin is ground in an offset manner so that the circle is actually at an angle to the face, whereas concentric pins are circular in relation to the pin itself. plainly you find engineering drawings difficult to understant ;D  paul |
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Post by mrgrimsdale on Jan 15, 2009 13:26:50 GMT
of course there is a "flat" side jacob, that is the essence of this type of design the pin is ground in an offset manner so that the circle is actually at an angle to the face, whereas concentric pins are circular in relation to the pin itself. plainly you find engineering drawings difficult to understant ;D paul Look closer and read the text. It's an 'oblique cone'. Think of a dunce's hat; conical all the way, but worn at a jaunty angle ;D ;D No flat sides at all. Anyway Paul you know you always agree with me eventually, after you have thought hard about it for a week or so! |
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Post by engineerone on Jan 17, 2009 15:15:59 GMT
actually jacob i don't agree, but found the following lie nielson stuff which would be useful to check out uk.youtube.com/watch?v=7yg7ntJKNJQtakes you there it is there film about using their new item paul |
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Post by mrgrimsdale on Jan 17, 2009 16:11:41 GMT
Interesting. Draw-bore pins and dowel plates becoming fashionable!
Using a dowel plate loose like he does is OK for a demo, but for regular use it needs to be fixed in a permanent housing in your workbench. You'd seriously hammer your bench top if you had a lot to do, specially the bigger sizes. And it's easier if fixed.
Not clear why he needs a draw-bore pin at all on this light job. Instead I'd make the dowels a lot longer say 2x the workpiece thickness, with a shallow taper for half the length. Then you just glue up the M&T and wang them in right through, with glue to lubricate them, or without glue if you really want to prove a point!
Drilling through the mortice - I'd do either before cutting the mortice (if I remembered!) or afterwards with a bit of scrap in the hole to stop breakout - OK you can't see it but you could be weakening the mortice sides.
Also I'd have longer tenons and the peg hole set further back for strength - at least 1/3 of the tenon length back, for strength. His are much too near the edge IMHO
Traditionally most pegs were not dowels at all - a round dowel is a difficult thing to make unless you have a dowel plate, but a round hole is easy. Hence square (cleft) pegs in round holes. Often you can't tell, as the peg gets compressed into the hole, and the only clue is 2 little ears giving the end of the peg an 'eye' shape at the front end, but round at the far end where it has been pressed through the whole length of the hole.
I wouldn't cleave the pegs in his way - from a thicknessed piece of scrap, instead I'd cleave all 4 sides in order to avoid cross grain.
If you ever see an obviously square peg then it was likely to have been fitted into a square hole - for rustic effect only; not functional.
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