Thread: EPIGLUE: Gap filling properties question

Groggy

Finewoodworking did some glue tests some years ago, Titebond liked the results so much they bought the web publication rights so you can read it here (0.9Mb file) http://www.titebond.com/Download/pdf...urGlue_FWW.pdf

except for polyurathane, all the glues tested were strong enough for a gappy joint -- HOWEVER, if I'm reading the artical correctly, the gap tested was only 1/64 in, about 0.4mm

Many thanks Ian, the gap is 4 thou which I think is 0.1016 millimeters, so I should be ok. I will add some oxide so that will thicken the mix slightly and slow sagging (I hope). I'll have a good read of that article.


(clicks off into the internet...)

EDIT: Actually, it just occurred to me that my feeler gauges might be metric, I better check that - it is possible the gap is .4mm, not 4 thou.

Groggy
don't forget there are a number of ways to pack out a loose M&T joint without resorting to a "gap filling" glue

Ian, it isn't the M&Ts, it is a beam face to beam face join. 2400mm x 135mm faces with a dovetail pair at each end. At some points there are minor variations and it would be nice to have the glue sort it, otherwise I could chase my tail for a while on this one. I plan to have one more go at marking and scraping then I think the glue can take up where I leave off.

PS - I can't run this over the jointer, it weighs nearly 200 kgs.

Groggy

is a sprung joint an option? -- i.e. you create a deliberate gap which is taken up by the clamping

is the joint structural or cosmetic? -- if structural, you may want to consider something like Selleys 308 High Stress Wood Glue, the accompanying info includes "Gap filling (up to 1.3mm)"
see Selleys 308 High Stress Wood Glue

You could also try the 24 hour Techniglue. It's a 2-pac epoxy resin that will fill almost any gap, takes pigments very well and is almost indestructible.

I believe Carba-tec stock it, it's not exactly cheap but it goes a long way.

Hi Groggy,
If we're talking options then Bote Cote also do a very good glue, the equal of Techniglue but cheaper and good gap filling. Be careful with oxides, if you use too much the epoxy won't cure completely.

Cheers
Michael

I already have the Epiglue so I am interested in the properties of it in particular. Selly's 308 is the only glue I have had a failure with (about 20 years ago) so I'm a bit wary of that stuff. Most likely a batch issue but once bit, twice shy, as they say.

Groggy
I think it comes down to whether the joint is structural or not, and if it is structural what are the consequences of the joint failing.
For a "gappy" structural joint I'd feel happier if there were some shear connectors on the joined faces to ensure that loads were evenly distributed between the two halves of the beam.

If the joint is purely cosmetic, any gaps could be concealed by inserting a fillet into the finished joint.

If this was a guitar neck the luthier would just hide glue in a piece of veneer to fill the gap and then shave that down for a fit. Of course this is a workbench so this may be too fiddly. Not being a luthier I am guessing that hide glue is chosen as your final glue choice will stick to it later, but most modern glues will not stick to themselves. Again, I'm not a luthier. I'm just someone that finally got to the last page of your workbench thread and am now ready for the next episode.

Jim

Originally Posted by jimt1

I'm just someone that finally got to the last page of your workbench thread and am now ready for the next episode.

Umm, a bit long isn't it...

It has to wait now a bit longer too. I need to make a bed so that will take a week of spare time, starting this afternoon.

To clear up the arguement.
Epox-E-Glue by BoatCraft is ultimate strength and loves gap and is heaps cjheaper than Techniglue or EPI Glue. It has heaps of Thixotropic Agent added which means it will not sag. If your joint is too tight with Epoxy Glues and all of the glue is squeezed out then you will end up with a weak joint.

Also coarse sand (40 to 80 grit) with the grain just before gluing to remove oil, oxidation or degraded grain and apply the glue. Clamp only tight enough to hold the two components together. Remember; too tight and squeeze the glue out and you have a weak joint.

Only other tip is when gluing end grain - paint the surfaces with Bote Cote first and let it soak into the timber and gell before applying the glue. Otherwise the resins can be drawn out of the glue and again you will have a dry joint.

If you have tight joints (no gap) and can clamp tighty (except endgrain) use Purbond as it gives good results, is easier to clean up & does not leave a glue line.

Originally Posted by jimt1

If this was a guitar neck the luthier would just hide glue in a piece of veneer to fill the gap and then shave that down for a fit. Of course this is a workbench so this may be too fiddly. Not being a luthier I am guessing that hide glue is chosen as your final glue choice will stick to it later, but most modern glues will not stick to themselves. Again, I'm not a luthier. I'm just someone that finally got to the last page of your workbench thread and am now ready for the next episode.

It's only for a workbench !! Whay thh fuss?

You could forget about using glue and just nail laminate the join and it would be more than plenty stong enough !!

if the gap's too unslightly, run a router (on a straight edge) down the join after the top is finished and glue in a fillet

Ian, somehow the idea of driving a nail into a 60mm dovetail doesn't thrill me

The epoxy is only for the skirt and dovetails on the endcaps where they join the skirt. The rest of the top is titebond II.