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View Full Version : Stabilising knots



taz01
16th November 2018, 11:36 PM
I'm creeping along in my work bench build (Moravian style bench), but have made a rookie mistake (as i am a rookie after all) of not planning the layout properly.

In the first cross beam between the two legs I've got a knot right where a mortice will be to allow for a wedge to hold it together.

I've seen on youtube people stabilising knots using west system epoxy, but are there other alternatives to save me buying some just for this? Would wood filler, or regular food glue work?

Any advice would be most helpful.

I've attached a 2nd photo showing a similar bench to illustrate the wedge placement. https://uploads.tapatalk-cdn.com/20181116/d12a289059158c17c089365ce889575b.jpghttps://uploads.tapatalk-cdn.com/20181116/173cf67bbee8593ba2d23806005ffb16.jpg

NewLou
16th November 2018, 11:57 PM
Nice Work

I think Ca glue or even some epoxy can be used for stabalising knots look into this a bit deeper with a few searchers though memory is a bit rusty on this one

heres a starter

https://sawmillcreek.org/showthread.php?223513-Epoxy-and-Wood-Knots

Regards Lou

ian
17th November 2018, 02:00 PM
runny super glue (cyanoacrylate). Not sure about Australia, but in Canada I can get super glue in 3 viscosities, "runny" as water, like thin syrup or like thick honey

FenceFurniture
17th November 2018, 06:19 PM
The problem with knots is that they tend to shrink more than the surrounding timber...and then fall out. The glue should prevent the latter but won't prevent the former. This could particularly be the case with so called kiln dried timber, such as radiata pine.

ian
17th November 2018, 06:57 PM
But if the OP is using really sharp tools and takes their time, they should be able to cut their wedge mortise through a stabilised (or glued in) knot, which if it falls out later won't really matter, or can be repaired with a dutch man.
It might even pay to cut the knot out now and do a dutch man repair.

taz01
17th November 2018, 07:25 PM
But if the OP is using really sharp tools and takes their time, they should be able to cut their wedge mortise through a stabilised (or glued in) knot, which if it falls out later won't really matter, or can be repaired with a dutch man.
It might even pay to cut the knot out now and do a dutch man repair.Thanks all,

I'm definitely taking my time, mostly through having to keep the noise down so not to annoy the neighbours!

To make the mortices I'm clearing much of the waste using a brace then chiseling the rest. I'm taking my chisels up to 8k grit, then honing a bit on a strop so should be sharp enough.

As this is only my first workbench, and largely a exercise in joinery, it's not need to last forever though and as the bench dismantles any piece can be easily replaced.

I've never heard of a Dutch man so I've a bit of research to do.

Thanks everyone.

ian
17th November 2018, 08:05 PM
what is a dutchman?
see here https://en.wikipedia.org/wiki/Dutchman_(repair)
and here https://makezine.com/projects/dutchman-wood-repair/

FenceFurniture
17th November 2018, 10:25 PM
But if the OP is using really sharp tools and takes their time, they should be able to cut their wedge mortise through a stabilised (or glued in) knot, which if it falls out later won't really matter, or can be repaired with a dutch man.
It might even pay to cut the knot out now and do a dutch man repair.Yeah, more than anything I'm just saying to be aware of the potential for it.

Alkahestic
18th November 2018, 12:06 AM
If you only want a small quantity of epoxy for this job, Boatcraft do a sample Bote Cote pack (https://boatcraft.com.au/Shop/index.php?main_page=product_info&cPath=15&products_id=699&zenid=d96fe5ae1239aa1ed753f98cccc507ee). It's a really easy to use epoxy and for $15 you can't go too far wrong at all.

Mnb
19th November 2018, 06:00 PM
You could cut it out and glue another bit in - I assume that's a Dutchman.

You could make the wedges horizontal instead of vertical and not have to cut into the knot at all. Look better anyway in my opinion.