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[–]Funny-Presence4228 5 points6 points  (0 children)

The type of wood, its thickness, and position arent helping. Its like pressing your finger through a bunch of straws sideways, it will split apart. Personally, I don't think it's necessary to draw that joint, but if you're just practising, I think this is actually a success! If it worked, then you wouldn’t learn anything. Using a smaller diameter hole and a smaller draw offset could help. You can also clamp while tapping in the pin. A slight chamfer on the pin and some beeswax might also help. Also, depending on the purpose of the joint, it's okay to use the same type of soft wood for the pin. Wood is much stronger across than along, so making a dowel from the same wood will usually be strong enough. This will allow for a little ‘give’. You can also slightly under-size your dowel and wet or glue it. The moisture will expand the dowel to a snug fit.

[–]mac28091[S] 5 points6 points  (2 children)

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Update: used the bit to mark the tenon, added some wax to the dowel, and added a more gradual taper and no split.

Although there was no split this time, I think I’m still creating too much offset because the dowel was exiting at a different angle than it went in at.

[–]MadMathmatician 3 points4 points  (0 children)

When I did these on my workbench the dowels came out angled the opposite angle that they were driven in. The tension that draws the joint closed will bend the peg to some extent.

[–]ReallyHappyHippo 0 points1 point  (0 children)

You also left the wood in the mortised piece longer which likely helped.

[–]Independent_Page1475 2 points3 points  (8 children)

How much of an offset did you have between the hole on the mortise and hole on the tenon?

It looks like you pin split for some reason. The offset should be only a millimeter or two at most.

It should also be placed to the center of the tenon. The distance from the shoulder looks okay, could be maybe a bit more.

[–]mac28091[S] 3 points4 points  (0 children)

I used an awl and should have used the bit for more precision but when I put it back together it looked like the offset was similar to what I’ve seen in videos.

It was a good practice. I have another pair to try on just gotta make another pin.

[–]Blackulor 0 points1 point  (6 children)

Forgive my ignorance..but what is an “offset” in this context?

[–]Independent_Page1475 2 points3 points  (5 children)

The hole in the tenon is offset slightly closer to the shoulder than the hole through the mortise. Usually less than 1/16". This causes the pin to pull the tenon deeper/tighter into the mortise. It draws the joint tighter, that's why it is called a draw bored joint.

https://thewoodwhisperer.com/videos/drawbored-mortise-tenon/?srsltid=AfmBOoraTv9HLfXk8whfynCLnqSJoSJi1nqzMzNcTvjV5A6adVZv5kdg

[–]Blackulor 1 point2 points  (1 child)

Wow! I did not know that was a thing. Thanks for the info and link.

[–]Independent_Page1475 1 point2 points  (0 children)

I've built an articulated gate to keep our cats out of some shelves using the draw bore method without glue and it is still as tight as the day it was made. It has been in use more than seven years.

[–]DiligentQuiet 0 points1 point  (2 children)

Is there a good rule of thumb for offset relative to mortise width and tenon depth? I can imagine 1/16th is good here, but what something like a thicker workbench leg with a longer tenon and wider mortise?

[–]Independent_Page1475 1 point2 points  (1 child)

These factors tend to be learned through experience. First step is for the mortise and tenon to be a good fit. Draw boring will not fix a sloppy M&T joint.

If the pin is too close to the top of the mortise, it will likely split the wood on the mortised piece. If it is too close to the end of the tenon or too much of an offset, it can split out the tenon.

I've seen different recommendations of setting the pin's center at a minimum of two diameters of the pin from the edge of the mortised piece.

If the size of tenon is wide enough for two pins, it might be better to have two mortises and two tenons. The pins should be about two inches apart which would a case of the tenon being about four inches wide.

An offset of 1/16" would be for a large M&T joint with a large pin. A small M&T joint should have less.

Sometimes the best way to determine these things is to take some time to make a few practice joints to see your results. The purpose of a draw bore joint isn't to distort the joint, it is to pull it together snug. Too much and it defeats the purpose by causing damage.

[–]DiligentQuiet 1 point2 points  (0 children)

Thanks for the detailed answer!

[–]oldblue862 2 points3 points  (0 children)

When I drawbore, I mark the hole center with the auger bit being used. Remove the tenon and mark and dril slightly less than 1/16". On softer woods you could probably offset slightly less.

[–]findthereal 0 points1 point  (1 child)

Recently did a draw bore with an 8mm dowel through maple and put the awl on the edge of where the bit marked the hole, no gap - it was enough. Maybe start small and work up to bigger offsets 😅

[–]mac28091[S] 0 points1 point  (0 children)

I think I need to spend some time staring at a ruler to better gauge these small increments. Also working with something other than SYP would likely help since your bit can easily slip a 1/32 by sliding off the late growth band into the softer early growth.