Drawbore questions

[Michael Ray Smith]

Two questions related only by the the fact that they deal with drawboring.

1. Do you really need drawbore pins like those sold by LV and LN? I find video demonstrations of drawboring that don't use a metal drawbore pin; they just drill the offset holes and drive the wooden pin into place.

2. As I understand it, with you construct an angled M&T joint, the "front" side of the tenon is cut at 90 degrees to the mortised piece. If it were cut at an angle, the tenon would act as a wedge that would tend to split the mortised piece. But if you drawbore an angled tenon, do you offset the holes so that you pull the tenon into the mortise at 90 degrees or at an angle?

[Mel Fulks]

With modern clamps and work done in a shop ,I don't see a need for the pins if glue is used. Pegs are then an after assembly detail and insurance. Without clamps and glue the draw bore pin is useful.

[ken hatch]

With modern clamps and work done in a shop ,I don't see a need for the pins if glue is used. Pegs are then an after assembly detail and insurance. Without clamps and glue the draw bore pin is useful.


Mel,

A small quibble, Pining after assembly ain't draw boring :).

ken

[Bob Glenn]

I don't do much draw boring, however, I have a long tapered metal punch that I use when necessary. Much cheaper than the alternative. The purpose of a draw bore pin beside pulling the join together, is to burnish the inside of the holes to make it easier to drive in the wooden pins.

[Mel Fulks]

Ken, gently stated and entirely true. My own take just comes from dealing with whether the buyer wants to see the pegs....and working for some eccentric bosses....excuse the redundancy. One guy insisted on mortise and tenon construction ,clamps ...but no glue, then pegs that were glued. He said the pegs would show up after painting ,course they never did since they really were not under tension and were glued.

[Nicholas Lawrence]

Limited experience with draw boring (mostly monkeying around with practice joints in scrap), but in the event it is helpful, here goes:

1. Schwarz did an article a while ago on using punches or automotive alignment tools as a cheap alternative to drawbore pins. I think you do want to run a metal pin in there to knock down the near edge of the hole in the tenon, but if your pin (the wooden one) is tapered, and then sawn off flush on the far side, you may be able to get away with it without leading with a metal pin. Your results will probably vary based on your choice of material.

2. I am trying to picture what you are trying to do, and what I am coming up with is something like installing a brace at a 45 between a table top and a leg, with a tenon on each end of the brace set into mortises in the top and the leg. If that is the kind of thing you are doing, I think you want the holes bored so they are at a 90 to the surface you are joining the angled piece to.

[ken hatch]

Two questions related only by the the fact that they deal with drawboring.

1. Do you really need drawbore pins like those sold by LV and LN? I find video demonstrations of drawboring that don't use a metal drawbore pin; they just drill the offset holes and drive the wooden pin into place.

2. As I understand it, with you construct an angled M&T joint, the "front" side of the tenon is cut at 90 degrees to the mortised piece. If it were cut at an angle, the tenon would act as a wedge that would tend to split the mortised piece. But if you drawbore an angled tenon, do you offset the holes so that you pull the tenon into the mortise at 90 degrees or at an angle?

Michael,

The answer to your first question is yes and no. I have pins and I might need them once a year or so and I draw bore almost every M/T joint I make. The pins can help if you are working heavy timber like on a work bench but for most assembly work if it is a tight fit a clamp across will get it close enough to drive the peg home. I would guess 90% of the time neither a clamp or pin is needed.

I'm really not understanding your second question but the draw force is going to be 90 degrees to the draw bore.

BTW, most of the time I do not use glue on my draw bored M/T joints. You can look at it as belts and suspenders, you need one but not both. A pinned M/T is another story.

ken

[Derek Cohen]

Two questions related only by the the fact that they deal with drawboring.

1. Do you really need drawbore pins like those sold by LV and LN? I find video demonstrations of drawboring that don't use a metal drawbore pin; they just drill the offset holes and drive the wooden pin into place.

2. As I understand it, with you construct an angled M&T joint, the "front" side of the tenon is cut at 90 degrees to the mortised piece. If it were cut at an angle, the tenon would act as a wedge that would tend to split the mortised piece. But if you drawbore an angled tenon, do you offset the holes so that you pull the tenon into the mortise at 90 degrees or at an angle?

Hi Michael

1. I do not use drawbore pins to drawbore (I do have the LV pins). Drawboring is a process of inserting wooden pegs into off set holes, per se. The metal pins are used for either (a) to test out a joint, or (b) to hold a joint temporarily.

2. As mentioned above, drawboring involves a set of offset holes. The positioning of these holes is important. They must pull the tenon into the mortice. This can only occur if the holes are perpendicular to the mortice.

Regards from Perth (Edinburgh at present)

Derek

[Tom M King]

For what it's worth, the biggest failure rate that I see on 200 year old window sash is too aggressive drawboring-especially if the part is quarter sawn. I think it's fine for heavy stuff, and I have pulled out some bent 1-1/2" diameter draw bored pins in framing that was still fine. I've stopped doing it for small parts like sash stiles and rails, and cabinet doors after what I've seen in old sash.

[Michael Ray Smith]

Here's a crude sketch showing a 45-degree M&T joint with the shape of the tenon in dotted lines. The circle is the hole drilled through the mortised piece. Should the hole in the tenon be offset to draw the tenon in the direction of the arrow marked 1 (parallel to the right side of the tenon) or in the direction of arrown marked 2 (parallel to the left side of the tenon)? I'm thinking 2.

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[Mel Fulks]

Tom makes a good point about the sash especially with that brittle long leaf pine. In that regard I can see the appeal of the northeastern white pine for sash ,and it's easier to cut.

[Zach Dillinger]

I will drawbore large-ish frames together, often without glue, for things like joined chests of drawers but I share Tom's observations and concerns with drawboring on smaller work pieces. I completely stopped drawboring those types of things on the advice of Carl Bilderback (RIP Carl) after describing what I was seeing.

[Tom M King]

Tom makes a good point about the sash especially with that brittle long leaf pine. In that regard I can see the appeal of the northeastern white pine for sash ,and it's easier to cut.

Most of the old houses around here aren't painted on the interior. Those that do have interior paint, only have it in a room or two. That leaves no choice but to use the same wood. If sash are to be painted inside and out, I'm not a purist to the point of wearing Lindsey-Woolsey underwear, and look for something easier to work. As a matter of fact, I'd like to get my hands on some of that White Pine right now for four sash I need to make. Do you know of a good online source for top quality material? I only need enough for four sash, and it's not worth my time to drive somewhere to get it. Thanks,

[Mel Fulks]

Oh,yeah ,Tom I've read enough of your posts to know you don't make inaccurate repairs. I was just referring to the understandable switch to it when it became available in the South. Don't know anything about online dealers but I'm in Richmond and we have an excellent local company called LUMBER SALES. I don't know how much area they cover in buying and selling but they tend to only buy from the same dependable suppliers.

[Patrick Chase]

Here's a crude sketch showing a 45-degree M&T joint with the shape of the tenon in dotted lines. The circle is the hole drilled through the mortised piece. Should the hole in the tenon be offset to draw the tenon in the direction of the arrow marked 1 (parallel to the right side of the tenon) or in the direction of arrown marked 2 (parallel to the left side of the tenon)? I'm thinking 2.

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I would draw it straight down (arrow 2), though that would apply a cross-grain load component to the tenon.

I think it also depends on how you lay the joint out. I always make a vertical mortise face (in this case the one on the left) my datum/registration surface, such that the tenon is always biased against that side of the mortise. The tenon therefore slides up and down, hence my suggestion above.

[Pat Barry]

I would draw it straight down (arrow 2), though that would apply a cross-grain load component to the tenon.

I think it also depends on how you lay the joint out. I always make a vertical mortise face (in this case the one on the left) my datum/registration surface, such that the tenon is always biased against that side of the mortise. The tenon therefore slides up and down, hence my suggestion above.
You must do a lot of this type of work Patrick. Perhaps you could show us some of your work sometime? :)

[Brian Holcombe]

Here's a crude sketch showing a 45-degree M&T joint with the shape of the tenon in dotted lines. The circle is the hole drilled through the mortised piece. Should the hole in the tenon be offset to draw the tenon in the direction of the arrow marked 1 (parallel to the right side of the tenon) or in the direction of arrown marked 2 (parallel to the left side of the tenon)? I'm thinking 2.

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How much short grain do you have after the hole?

[Warren Mickley]

Here's a crude sketch showing a 45-degree M&T joint with the shape of the tenon in dotted lines. The circle is the hole drilled through the mortised piece. Should the hole in the tenon be offset to draw the tenon in the direction of the arrow marked 1 (parallel to the right side of the tenon) or in the direction of arrown marked 2 (parallel to the left side of the tenon)? I'm thinking 2.

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We always mark out in the #2 direction as Patrick suggested. The mortise wall to the left bears a lot of the stress, so that should be kept tight, but you want clearance at the bottom of the mortise for the tenon to be pulled into. The pin is usually quite a bit closer to the shoulder than the end of the tenon.

For the skeptics, here is a picture of a blacksmith shop I worked on in 1983. The shop was reconstructed from photographs and an existing foundation.

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[paul cottingham]

I draw-bore pretty much every mortise and tenon joint i make. I like the fact that if the glue fails, the joint will still be sound.

never thought of using clamps to close the joint, rather than a drawbore pin. I have the LV ones, (second set, i bent the first one) and use them, but clamping intrigues me.

[Brian Holcombe]

We always mark out in the #2 direction as Patrick suggested. The mortise wall to the left bears a lot of the stress, so that should be kept tight, but you want clearance at the bottom of the mortise for the tenon to be pulled into. The pin is usually quite a bit closer to the shoulder than the end of the tenon.

For the skeptics, here is a picture of a blacksmith shop I worked on in 1983. The shop was reconstructed from photographs and an existing foundation.

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That's a cool shop Warren, nice joinery!

I'm certainly not a skeptic, practically the opposite, every piece of advice you've posted and I have employed has worked beautifully for me. I appreciate the picture all the same.

[Pat Barry]

We always mark out in the #2 direction as Patrick suggested. The mortise wall to the left bears a lot of the stress, so that should be kept tight, but you want clearance at the bottom of the mortise for the tenon to be pulled into. The pin is usually quite a bit closer to the shoulder than the end of the tenon.

For the skeptics, here is a picture of a blacksmith shop I worked on in 1983. The shop was reconstructed from photographs and an existing foundation.

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Are you the blacksmith there Warren? What were you making?

[Warren Mickley]

The blacksmith was Tom Tyson. I don't know who the photographer was.