Red Oak VS Ash For Draw Bore Pegs

[James White]

I am in the process of assembling my Roubo bench and had two Ash pegs break on me while driving them in . I am wondering if red oak is less likely to break. It seems the oak bends a little easier than the ash. So I am thinking it my be less brittle. The bench is made of ash so that is what I started with. I don't have any white oak or I would have used that.

James

[Robert Rozaieski]

Were the pegs split out or sawn? I suspect grain runout to be the culprit not wood species. Ash should work just as well as oak. Both are fairly springy as long as they are straight grained.

[James White]

Hi Bob.

They are riven and then driven though a 1/4 steel plate that I drilled a series of holes in. They start at 5/8" then go down to 1/2", 7/16 and then 3/8" finished size. Although I only did two from the red oak they seem to come out allot smother than the ash. The ash has lots of stringy burs on them. Not gouges but small burs. I wonder if a little wax on the pegs would help them go in smoother. I am not gluing these joints so that the bench can be knocked down if ever needed. I am doing a 1/16" offset for the holes which seems like a lot when you look at the assembled joint. I have to say it sure looks like there is no way that that peg is going though those misaligned hole. But it does to my surprise. I am just a bit nervous having had to drill two of them out.

James

[glenn bradley]

1/16" is a lot of offset for a 3/8" peg. Did you chamfer the hole in the tenon? If not, you could chamfer the end of the peg (which I assume is overly long) and them cut it flush. Wax, definitely.

[Michael Faurot]

My experience with draw bore pins/pegs has come from what I've learned watching Forgotten Hand Tools, by Christopher Schwarz. In that video, Christopher Schwarz recommends oak. So far, all the pins I've made from red oak have been fine.

[Chris Friesen]

I rived the pegs for my bench from white oak, and still splintered a few while driving them in.

Wax the pegs. Also, make sure you taper the initial bit of the pegs to ensure that they make it through the offset inside the drawbored joint. You want to be able to push it through the tenon by hand before resorting to a mallet.

[Robert Rozaieski]

James,

I agree with Glenn. An offset of 1/16" is quite a bit of offset for a 3/8" peg, which is pretty thick. I agree with putting a bit of wax on the pegs. You could also try driving the pegs through the plate in the other direction (the peg direction, not the plate direction). The plate seems to be lifting the grain slightly and shaving the last little bit off the peg in the other direction may help. In addition to waxing, you could burnish the pegs with some shavings before driving them. This will smooth them out some. Also, as others have suggested, a long taper will be necessary with such a large offset. Make the taper on the peg really long and make the peg about 2-3X longer than finished length to allow the long taper to be driven completely through. If the peg is flexing a little too much while being driven you can make guide blocks to help. Bore a hole the next size up from the peg hole size in several scraps. It will be loose enough that the peg will not bind in the guide block but the hole will be small enough to prevent the peg from flexing to the point of breaking. When driving long pegs it can sometimes be difficult to prevent excessive flexing whith only your hand while driving them so the guide blocks can help. You can stack several blocks if you have a real long peg and hold the guide blocks instead of holding the peg. Remove one block at a time as you drive the peg until the peg is driven as far as you need. Also, because you have such a large offset, you may have some binding in the exit hole. Wax the exit hole really well and you may also want to use a backing block on the exit hole (one of your guide block will work well) to prevent the peg from splitting off the edge of the hole as it exits if the fit is too tight due to the offset. Good luck!

[James White]

Hi Everyone,

Thank you for the tips. I just tried two more pegs with wax. It made a big difference.

As far as the offset goes I am following the advise of Chris Schwarz. In fact for this kind of work he recommends 3/32"!

http://sdguild.rcwa.googlepages.com/Drawboring.pdf

At first I thought he must be out of his mind. So I started with less than 1/16" and I didn't like the results. The joint was just a bit mushy. The first one that broke was more than likely because I didn't put enough taper on it. The second one could have been a fluke. For sure the lack of using a draw bore pin is part of the problem. By the way these are 4" deep blind holes. I don't have a 3/8" bit long enough to go through the 5" leg. Therefore I can only taper the fist half inch of the peg. I think the wax will do the trick. I more or less wanted to make sure ash was suitable and just as good as oak.

Bob,

I will try that stacked block trick. I think that is a neat idea.

James

[David Keller NC]

I've a fair amount of experience with red and white oak since they grow prolificly in this area, and I sometimes saw/split my own lumber. My thought here is that both red and white oak are quite flexible, red oak splits very, very easily in contrast to white oak, which is a bear to split.

The issue would then be that the red oak tends to split at the end that's driven with a mallet, so a drawbore peg might wind up pretty ugly at the outer surface of the joint. If that's not a concern, then certainly riving the pegs out of red oak is very easy.

If white oak doesn't grow where you live and you can't obtain a piece of firewood for the purpose, then there are some alternatives that will be less likely to split at the driven end. In particular, hickory or pecan would be excellent for the purpose - they're quite flexible, hard, and don't split easily. In fact, you may find that it's wise to split these when green, then let the pegs dry, because riving dry hickory is nearly impossible.

[Chris Friesen]

By the way these are 4" deep blind holes. I don't have a 3/8" bit long enough to go through the 5" leg. Therefore I can only taper the fist half inch of the peg.

It would be easier with a longer taper...have you considered using a spade bit until the tip just pokes through, then finish up from the other side?

[Sean Hughto]

long brad points are not terribly expensive and readily available:

http://www.woodcraft.com/product.aspx?ProductID=146637&FamilyID=5567

just fwiw