Doweling jig advice needed

[user22161]

I have an old Stanley 59 dowel jig but rarely use it these days unless grain creates problems. Usually use these cheap dowel centre pins. Drill dowel hole(s)in one surface, insert pin(s) and smack it against the other surface leaving pop mark to drill. https://www.amazon.co.uk/Silverline-733 ... B000T9UCCI

Strange how tests show dowels can be stronger than tenons. If we take a piece of 2" x 1" with a 1 1/2" x 1/2" tenon, the glue area is 4" x depth, whereas 2 x 1/2" dowels only give a glue area of 3.142" x depth. (if my maths is correct) Were they hardwood dowels as opposed to softwood tenons?

 

[MikeJhn]

To be an equivalent to the 1 1/2" x 1/2" tenon, you need three x1/2" dowels and because the dowels are not flat sided the glue area will be even greater.

 

[user22161]

To be an equivalent to the 1 1/2" x 1/2" tenon, you need three x1/2" dowels and because the dowels are not flat sided the glue area will be even greater.

You many be right but the dowels would be touching each other rather than the mortise so not a direct multiplication of area. I think it would be unusual to use 3 x 1/2" dowels anyway on a but joint that size, all depends on the load expected.

 

[custard]

Face-grain to face-grain is much stronger than anything to end-grain, and dowels are 50% end-grain.

Dowels are no where near 50% end grain, but loose tenons are more end grain than a dowel, taking length to dia/thickness as a percentage.

I think what Steve meant is that two of the four quadrants in the mortice hole are predominantly end grain. Therefore, as a rough approximation, 50% of the mortice hole is end grain. It's the hole not the dowel.

However, this is further complicated by the fact that most of the dowels I've measured are slightly oval in cross section (pretty inevitable really, given the changes in humidity throughout the dowel distribution pipeline). It drives a coach and horses through any kind of experimental repeatability, as there'll be variation in the degree of ovality (if that's a word!) and in the orientation of the longer diameter of the oval dowel within the hole, is it against the long grain quadrants or against the short grain quadrants?

For these reasons I stay away from debates about dowels versus M&T's versus dominos etc, there are too many variables to make the discussion anything other than futile.

However, as a practical furniture maker of many years experience I know there are situations where dowels are extremely useful, and then I'm happy to use dowels, confident that if I take appropriate care I'll have a positive outcome.

 

[MikeJhn]

As much as I respect your opinion custard, and its nice of you to try and explain away the stupid statement that dowels are 50% end grain, but that is what was said, not that a mortice hole is 50% end grain.

 

[Jacob]

In my experience - stuff to repair - dowels fail more than any other joint.
Mortice and tenons are always either wedged or pinned through. Belt n braces - will hold together even if the glue has gone

 

[woodbloke66]

In my experience - stuff to repair - dowels fail more than any other joint.
Mortice and tenons are always either wedged or pinned through. Belt n braces - will hold together even if the glue has gone

I think the classic one is with chairs where the back legs were doweled and then some little 'oik' sat on it and leaned it back, raising the front legs off the ground. Not that I've ever done that when I were a lad :lol: - Rob

 

[Jacob]

In my experience - stuff to repair - dowels fail more than any other joint.
Mortice and tenons are always either wedged or pinned through. Belt n braces - will hold together even if the glue has gone

I think the classic one is with chairs where the back legs were doweled and then some little 'oik' sat on it and leaned it back, raising the front legs off the ground. Not that I've ever done that when I were a lad :lol: - Rob

Yes chairs. I'd blame the chair maker!

 

[powertools]

Quote from Woodbloke.

2017. Silverline dowels are appalling...when I bought my Dowelmax some time ago the chap importing them from Canada told me that they were 'DIY quality' (his words) even though he supplied them with the jig. They vary in diameter so some are a reasonable fit and others are slack.
The Ax dowels on the other hand (and there are probably plenty of other makes out there) are consistently very tight in the holes and regardless of where they come from are a very good product - Rob
End of Quote

Sorry to question what you have said but I find it very hard to believe that someone selling a high end jig sells it with a pack of dowels that are not fit for purpose that would only bring into question the quality of the jig.

 

[powertools]

These videos on YouTube about the strength of a joint really only show the strength of the glue.
Anybody making a t joint that will be put under those sort of loads needs to rethink the design.

 

[woodbloke66]

Sorry to question what you have said but I find it very hard to believe that someone selling a high end jig sells it with a pack of dowels that are not fit for purpose that would only bring into question the quality of the jig.

Strangely, yes, so did I. The jig is superbly accurate and beautifully made but why he didn't go the extra mile and source decent accurate dowels is anybody's guess. What I do is to use them for rough assembly knowing that they can be relatively easily removed and then use more accurate, tighter fitting dowels for the final glue up - Rob

 

[Phil Pascoe]

I don't think I ever came across a failed dowel joint where the actual dowels failed - it was always poor design, short grained timber and/or dishwater glue and the joint would have failed whether it had had dowels or tenons. (And I've repaired probably a couple of hundred tables, chairs and stools. )

 

[Phil Pascoe]

Sorry to question what you have said but I find it very hard to believe that someone selling a high end jig sells it with a pack of dowels that are not fit for purpose that would only bring into question the quality of the jig.

You've never bought a brilliant saw with a lousy blade, then?

 

[transatlantic]

I have an old Stanley 59 dowel jig but rarely use it these days unless grain creates problems. Usually use these cheap dowel centre pins. Drill dowel hole(s)in one surface, insert pin(s) and smack it against the other surface leaving pop mark to drill. https://www.amazon.co.uk/Silverline-733 ... B000T9UCCI

Strange how tests show dowels can be stronger than tenons. If we take a piece of 2" x 1" with a 1 1/2" x 1/2" tenon, the glue area is 4" x depth, whereas 2 x 1/2" dowels only give a glue area of 3.142" x depth. (if my maths is correct) Were they hardwood dowels as opposed to softwood tenons?

The problem with these is that both holes have to be exactly in the same direction (well, one in the -direction). Not always easy if you can't use a drill press

 

[user22161]

I have an old Stanley 59 dowel jig but rarely use it these days unless grain creates problems. Usually use these cheap dowel centre pins. Drill dowel hole(s)in one surface, insert pin(s) and smack it against the other surface leaving pop mark to drill. https://www.amazon.co.uk/Silverline-733 ... B000T9UCCI

Strange how tests show dowels can be stronger than tenons. If we take a piece of 2" x 1" with a 1 1/2" x 1/2" tenon, the glue area is 4" x depth, whereas 2 x 1/2" dowels only give a glue area of 3.142" x depth. (if my maths is correct) Were they hardwood dowels as opposed to softwood tenons?

The problem with these is that both holes have to be exactly in the same direction (well, one in the -direction). Not always easy if you can't use a drill press

I do have a drill press but not much use when drilling the end grain so, as you say, drilling has to be accurate. May sell the 59 and buy a self centering jig. Also, I keep meaning to make a dowel maker ( have some 1 1/2" x 1/4" steel bar) as I'm fed up with bought lengths varying in diameter by silly amounts.

 

[MikeJhn]

I think in fact we are all of the same accord, dowels have their place in the scheme of things and are more or less the same as any other non-secured jointing system be they loose tenons or any other type of joint, the true tenon with wedge expansion piece's driven in is the most secure and the strongest joint available, but is the most difficult and time consuming, a simple dowel jig, readily available and cheap, or domino, relatively expensive, are all much of a muchness, the biscuit joint is really only an alignment aid, but does come in useful for non stressed joints, all of the above vary according to the skill of the operative and the quality of the dowel/domino/biscuit being inserted, the problem is everyone likes blind joints so the split tenon with the wedge insert becomes even more difficult to achieve and the dowel/domino will be called on again and again, so in effect only you can decide which joint to use according to what you are building if you want speed or strength.

 

[Raymond UK]

I think Mike just summed it up pretty good there.

Now, my use for the dowels is just to align panels for the end user so they can screw the screws in without going wrong. It’s vary rare I make flatpack stuff but sometimes I have to as shipping costs can vary immensely especially going abroad.

The new self centering jig has arrived today and does actually look promising. Comes in it’s own soft surround that’ll go nicely into one of the pillar drill drawers when finished.

Not tried it out yet as I’m waiting for an hand injury to heal up. (Not a wood work related injury) :mrgreen:

Not sure how the mm adjustment works. Seems a bit odd