Hot melt glue chucking

[Rhossydd]

Having read a few people here praise the technique of using hot melt glue to assist work holding, I thought I'd give it a try.

So the gun was cheap at the moment http://www.toolstation.com/shop/p24076 yes, £3.35

I've just tried sticking a scrap of Imbuya to an Oak blank, with precious little success.

So could someone that uses this give any pointers as to how to improve the quality of the bond please ?
I'm using the supplied clear glue sticks, are they a good choice or is there something much better ?
How rough do the surfaces to be bonded need to be ? Should I be scoring the surfaces and making them really rough ?
Could the relatively low temperatures in the workshop today hinder bonding ? Would heating the components with say a hot air gun or an iron help ?

Thanks in advance.

 

[finneyb]

Heat is critical to success in my experience . As you say heat with hot air gun etc may help and don't hang about putting the pieces together the glue cools very quickly. You could request permission to go into the heated house to do it

Brian

 

[AndyT]

I've used a similar gun and unbranded glue sticks ok.
I suspect you are right if your workshop and the pieces of wood are freezing cold - the glue will be chilling into itself without bonding. Try bringing the bits into the house and letting them get to a nice even room temperature first.
I found it best to put a row of thickish blobs, which could then all be pressed down, quickly, while they were still soft. You only have a few seconds to do this. A bit like laying patio slabs on dabs of mortar.

 

[CHJ]

Ultra cold work piece will chill the glue but I suspect that you do not have adequate temperature or volume in the glue in the first place with that small gun.

Used as seen here

there's usually 10-15 seconds at least to join the pieces, I had time to photograph this before mating the pieces, often on the lathe I have to wait a minute or more for the glue to cool enough so that it does not spray out if I start up.

But I do use a full size Bosh gun and the large sticks. Glue is bubbling.

Surface is not critical, it will bond to smooth wood as long as it's not contaminated with wax, oil or a lot of dust.

 

[Rhossydd]

Thanks all.
It looks like the temperature issue was the most significant.
I've lightly sanded the oak a bit more, then wiped any dust off with a damp rag, then left both parts against a radiator until warm to the touch, then squeezed on a fair old load of glue on quickly and cramped it up.
Interestingly, there seemed a lot more play(squidge?) as I pushed the parts together this time.
After being left to cool the joint seems solid enough and I've been able to get on with the turning without any further problems.

Chas; That was similar to the amount I used first time. The gun looks small, but it takes 11mm sticks and gets hot enough for the limiting factor to getting the glue through the gun being how fast I can squeeze the trigger.

For anyone else reading this and thinking of trying it: Buy lots of extra glue sticks, the first time you use the gun uses almost two sticks just to load the gun, then in use there's a fair amount of wastage dripping out of the nozzle whilst warming up/cooling down.
Cheaper than 5min epoxy, but maybe not always more convenient if you work in the cold.

The Toolstation deal with 50 sticks of glue works out at less than a tenner, so a good deal that ought to keep me going for a long time I hope.

 

[ericdockum]

Has anyone used Low Melt glue gun/sticks? Never tried them myself.

These have an application temperature between 120°C-140°C, which is probably some 70 Deg. C below the conventional hot melt guns. Try "low melt glue gun" in t'web.

I just wonder if as it operates at a lower temperature it suffers less from the shock cooling/premature set of hot glue onto a cold surface. Makes keeping the parts warm less of a rush. Also lower temp glue may be better for more delicate materials....

 

[lurker]

I have tried and failed
I find pva and paper fairly reliable

 

[chipmunk]

FWIW, WHen I last saw Nick Agar, he used a hot-melt "weld" around the outside of the two items to be joined.
I have used his method since I saw him demo it.

It has the advantage that you can see if it's parting company and there's no "open-time" when the glue's getting cold. You can also heat up the seam with a heat gun to separate the items after turning.

The other way I've tried is to use a brass plumbing flange shaped into a chucking face-plate heated on an electric hob. This helps you keep the joint hot on glueing up and by standing it on the hot-plate gives a neat way of separating things at the end.

HTH
Jon