Official Luthiers Forum!

I recently received a mini heating blanket from John Hall for use in repair work (removing bridges, fretboard extensions, and so on). I’m new to using heating blankets and am looking for some tips. What sort of temp am I looking for when it comes to these kind of repairs? How long should the part heat up before going at it with the separation knife? I’ve done these kind of repairs without the blanket in the past and I’m hoping this makes things a lot easier.

Any suggestions or things to watch for are appreciated. Thanks

Josh

_________________
Josh House

Canadian Luthier Supply
http://www.canadianluthiersupply.com
https://www.facebook.com/canadianluthiersupply?ref=hl
House Guitars - Custom Built Acoustic Instruments.
http://www.houseguitars.com

Good to see you Josh. I hope your shop is full and you're super busy!


If you start hearing cracking sounds, it's too hot

OK, seriously. Most glues will release at around 140*F so I wouldn't want to go any higher than say 160* just to be on the safe side.

_________________
My Facebook Guitar Page

"There's really no wrong way, as long as the results are what's desired." Charles Fox

"We have to constantly remind ourselves what we're doing....No Luthier is putting a man on the moon!" Harry Fleishman

"Generosity is always different in the eye of the person who didn't receive anything, but who wanted some." Waddy Thomson

a simple oven thermometer (the kind that has a flanged bottom stand will read the blanket temp. it takes about 90-120 seconds for a rosewood bridge to transmit the same temp to the glue. A little longer for ebony and I find that the glue needs about 30 seconds at temp to soften up good. I use one of Johns router controlers to control the voltage to the blanket. I always set it at variable and mid way and adjust till I am controling the blanket at 140F on a piece of scrap stock then move it in to position on the bridge. Wait 2 min. and test the joint with a seam knife.

Thanks Guys!

That was the info I was looking for.

Josh

_________________
Josh House

Canadian Luthier Supply
http://www.canadianluthiersupply.com
https://www.facebook.com/canadianluthiersupply?ref=hl
House Guitars - Custom Built Acoustic Instruments.
http://www.houseguitars.com

Something that i constantly do as i heat up something for disassembly, is feel the underside with my hand, meaning i reach in through the soundhole and feel the temp of the bridge plate and wood around the area, or the top and popsicle brace under the fingerboard.

Warm to the touch is generally ok, and means that the glue is ready to release. If things start feeling hot, you run the risk of all of the glue joints releasing, like the center joint or adjacent braces.

_________________
Jordan Aceto
Ithaca, NY

For bridges , it depends on the thickness and wood type. I use a very flexible pallet knife from an art store. You will know when it is hot enough when you can start the knife into the joint and feel the glue releasing. Be careful not to force things as you can lift grain and cause other damage. Patience is key
john

_________________
John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

Warming the pallete knife a bit beforehand helps too.

Pat

_________________
formerly known around here as burbank
_________________

http://www.patfosterguitars.com