Side bending

[Ian Davlin The Looth Group]

Do you have any pics of your set up and the broken side ?

[Paul Raymond Raymond Guitars]

I had been using the spring steel from Stew Mac, which is considerably more narrow and shorter than what is pictured here. Last night I found more of my own material and cut a 2nd piece, so now my sandwich will be fully encased with metal. The StewMac piece left quite a bit of the blanket exposed and perhaps I was loosing too much heat over the bouts…??

• This reply was modified 3 months, 1 week ago by  Paul Raymond Raymond Guitars. Reason: original pictures were too large to upload at the the same time

[Ian Davlin The Looth Group]

Try soaking the wood for a bit rather than a spritz. Also, that break is really short for mahogany. I would expect the grain to be longer and more frayed than broke. You may have to really baby that stuff. Like make that turn in increments and let it sit under heat at each stage before moving on. Where did the wood come from ?

[Paul Raymond Raymond Guitars]

Hey Ian…thanks….

[Paul Raymond Raymond Guitars]

I builder in my area had it. I did not know him but I saw on Facebook that his family was selling his tools and wood after he died. Was a good deal at the time…or maybe it wasn’t.

Thank you Ian…I’ll give it another go today. I have another set from him so fingers crossed!

• This reply was modified 3 months, 1 week ago by  Paul Raymond Raymond Guitars.
• This reply was modified 3 months, 1 week ago by  Paul Raymond Raymond Guitars.

[Michael Minton]

This seems laborious, but it has served me well. I can’t remember the last time I cracked a side (knock on wood, sic). I use SuperSoft (spritzed on and evened out with a paper towel) and a sandwich that has a parchment paper inner, and an aluminum foil outer (shiny side in). SuperSoft can leave some staining but that is a small price to pay. Like you, I start the bend around 240 at the waist, and move pretty fast. I never set the thermostat above 300 degrees. Where the radius change is small, you can move faster. Where it is tighter, you slow down a bit, but you still have to keep moving.

My diagnosis of what happened to you is you got too hot, and moved too slow, drying things out. If you can hear a very slight sizzle at the edge where the bending is occurring you are definitely warm enough. You should be able to feel the wood give as you bend the upper and lower bouts. 5-10 minutes for an entire side.

All that said, mahogany isn’t the easiest wood to bend, particularly if there is any figure.

[Michael Bashkin Bashkin Guitars]

Hi: I suspect you are bending to slowly. Once the wood is up to bending temp it is counterproductive to go to slow. If you take to long the wood dries out, becomes brittle and is prone to breaking. When I bend the upper bout I’d say it takes me about 45sec-1 min in a fox style bender and about 2-2.5 mins for the whole side. Keep in mind the wood is still wet at this point and steam is being produced and the wood is around 270-300. Also, it is important that the outside of the bend is supported by the bending slats.

For Mahiogany I spritz a bit heavier. I occasionally use super soft but I don’t think its necessary. I wrap the wood in parchment paper (it is not sealed shut), turn on the heat I use top AND bottom blankets. Once the wood starts delfecting under its own weight I will bend the waist about 80%, of the way then bend lower bout (20-30seconds), then the upper (45-60 seconds) then finish bending the waist. This is all done in the 250-310 F temp range.

Then I reduced heat to around 230-250 and let it sit for 10 min and then let it fully cool down. Most if the time I run it through a second heat cycle. With the side already fully bent and still in the bender I will bring it up to bending temp then back down to 240 ish and let sit for 5 min, then a full cool down.

There are many ways to do this and different variations but this has worked for me over the years.

[Paul Raymond Raymond Guitars]

Michael and Michael…thank you both. I am very frustrated as my second bend also broke. I had the wood quite wet, but as you stated, Mr. Baskin, I think I am moving too slowly. and perhaps getting too hot as well. The thermostat on my blanket is not the easiest to control though the blanket it self is the one pictured on the StewMac site, the T-stat is different and requires a lot of tweaking to maintain a goal temp.

I should have waited another hour or 2 and then I would have seen your replies. I hate loosing the material…it really hurts!

I may need to invest in a better controller and just work faster…thanks again.

Paul

[Paul Raymond Raymond Guitars]

thanks again to both of you. i first verified my silicone blanket was generating relatively even heat, which it is, then used the parchment/foil method and moved quickly…perfect bend. I think I’ve been too careful for all of my bends so far and have just gotten lucky until know. that said, this next guitar look like it will be wenge and not mahogany. many thanks.

Paul

[Paul M]

Not sure where you got your blanket but i got one off eBay that does not get hot enough. Or at least it doesn’t get as hot as fast as one that was given to me.

I use barbecue thermometers in my stack for monitoring temperature.

[Paul Raymond Raymond Guitars]

Hi Paul…mine may have come from eBay- I don’t quite remember. This weekend I used 1 of those infrared temperature guns all across the entire surface of my blanket while it lay flat on my bench. Mine is getting hot and is relatively evenly distributed.

When I bend I use a food thermometer, one with a 4 inch probe. After I assemble my sandwich I slip it in between the blanket and the wrapped wood…

[Michael Minton]

Paul, PM me if you need a couple more Mahogany sides. I have tons, and I’ll send you some just for the shipment cost if you want.

[Brock Poling]

I am just seeing this… one other thing worth looking at in a post mortem… the way this broke (and considering it was in the lower bout where things usually go ok) you might have some significant runout in this piece. If you get a lot of runout the grain can sometimes open up on you.

[Paul Raymond Raymond Guitars]

that makes sense, too. thanks, Brock.