BYO: The Pliage

Bones

In the picture it looks like you have blocks under the head and tail ends of the top but in the sketch it looks like just the tail end. That's why I thought it was a different fixture.

Do you have much of an issue with spring back (i.e. do you need to put in much over-bend to get the final angle)?

Thanks

Craig Bumgarner

Bones wrote:

In the picture it looks like you have blocks under the head and tail ends of the top but in the sketch it looks like just the tail end. That's why I thought it was a different fixture.

The picture shows the bending of the top with braces already attached. Because the braces are arched, so is the top, so I had to support the arched top with some arched cawls. As I mentioned before, bending the braced top was an after thought. Although this is what stimulated the idea of bending a joined top and the use of the heat blanket, the second time, I bent the top joined but unbraced and was thus able to dispense with the cawls, that is, like the sketch.

Do you have much of an issue with spring back (i.e. do you need to put in much over-bend to get the final angle)?

No, I overbend a little, so if anything when the top is glued to the sides, the bend actually lifts the arch a little. The main thing is you don't want to force the top down to the tail block as this will flatten out the lower braces some or even completely. Initially, I fussed with the angle to get it perfect but I've found the angle of the bend is not super critical within a degree or two as the top is reasonably compliant, so now I do it by eye. The pliage does not define the shape, it accommodates the top to the geometry of the braces and sides. That may sound like semantics, but it is an important distinction in concept.

Bones

Ok, thanks.

I'm going to contact the Titebond people to see what is the strength of it at elevated temp just out of curiosity. I'll let you know if I find out anything interesting but if you have not had any issues it's probably just academic.

noodlenot

thanks for the visual aid and clarification, Craig - i think that´s a method i could try! this is really becoming a nice build sub-forum... i hope no one minds it.
As for titebond, in spite of not much love from the guitar making crowd, Titebond III is said to be heat resistant (to some extent). I´m amazed that TB I (original) can withstand the bending temps,but maybe the heating element is not providing as much heat as a bending iron? Also, do you have any experience with that pliage method and hide glue? do you think it would work? i only joined one top with TB and i really prefer hide (or fish) glue.

thanks,
miguel.

Craig Bumgarner

I'm using Titebond original. I researched heat release on it a couple years ago and I seem to remember it is about 160 degrees. The test involves gluing a paddle to a block, putting weight on the paddle, putting the whole thing in an oven and slowly taking the heat up until failure. I have very limited experience with hot hide glue but I think it fails around the same temperature, maybe a little less.

That said, I've never managed to separate a serious joint glued with Titebond with much less than 300 degrees and even then it takes a hot, sharp putty knife into the joint to get it to separate. It does not come apart easily.

In the current Radius Question thread here on DB, MIguel posted a link to one of the de Bretagne forum pages which shows pictures of what appears to be a builder bending of a glued up top over a heated form (last post at the very bottom of the page).

http://www.benoit-de-bretagne.com/phpBB ... hp?t=10687

Luthier forums warn against using Titebond II or III, but I don't really know why.

For me, while I appreciate the attributes of hide glue, I find my building style, 30 minutes here, an hour and half there do not lend itself to turning on the glue pot and leaving it on all day as I gather many do. I've heard about preparing small brick of glue or small squeeze tube of glue and heating them in desktop water heater like on uses for tea. One of these days. Right now, so easy to grab the little bottle of Titebond. It appears Titebond (original) is widely used in lutherie, though HHG seems highly revered. I would be very surprised if someone could hear the difference.

noodlenot

well, with the risk of going off-topic, i guess i´m in a symmetrical position: i appreciate TB, but my way of building goes well with hide: easier clean-up, easier to disassemble the joint and non-toxicity (i don´t know if TB is toxic, maybe it´s not); plus, i have lots of spare time and that´sthe way i learned to do it... TB i use here and there, it´s good stuff. I want to try TB III for purflings, but now that i know of your way of doing the pliage, maybe i can try TB original.

cheers,
miguel.

Brian

Hi this is my first post. I have recently taken an interest in Gypsy Jazz and am interested in making a suitable guitar. I have made several guitars over the past few years and have just started researching this style.
My past experience and research would suggest that Hot Hide ( not fish glue) glue would be better in this situation . Should there be any separation ( visible or not) of the central seam when forming the pliage then as long as the join remained in contact the Hot Hide Glue would reactivate itself and form a strong bond.
As far as I understand this is one of the advantages of hot hide glue over the aliphatic resins like original titebond and PVA. If a tight bond joint fails you have to remove all of the old glue and start afresh.
Having said that I have only used original titebond for my previous guitars and have had no problems.
I think I would use hide glue on the top seam if it is to be used for a pliage using the above technique.

Cheers, Brian

Craig Bumgarner

A couple updates......

I successfully bent a pliage over a hot pipe for the first time this weekend. I had tried doing it a number of years ago without much success and came up with the heat and clamp method described earlier in this thread which I have used ever since. I've been heat bending wood recently for other reasons and thought I'd give a pliage over a hot pipe another go. Easy! I think the problem before was I just was not getting the pipe hot enough. This time I got the pipe up around 500F. At that temp, sprayed water on the pipe doesn't dance, it just goes puff. Sprayed a little water on the underside of the top at the bend line and it bent easy, less than 60 seconds.

The advantages of this are 1) it takes a lot less time than the heat and clamp method, 2) the bend is sharper which looks more authentic and 3) the bend retains the angle better. With the heat and clamp method, the wood retains some memory and some of the angle is lost after unclamping. Not with hot pipe, what you see is what you get.

Regards hot hide glue..... Been using it a lot more these days, along with fish glue. To make HHG work with my short periods in the shop, instead of the traditional glue pot, I use a small squeeze bottle to hold the glue and an electric tea pot with a rheostat to maintain water temp. The pot will bring water up to temp in 3-4 minutes and hold it there. The pot is plugged into a 30 minute electric timer, so all I do it push the button on the timer and the pot heats and in about 5 minutes the glue is ready to use. If I forget to turn the pot off, which I have done several times, the timer shuts it down automatically.

Bohemian

Congrats on your success.

What diameter was the pipe ?

Craig Bumgarner

Bohemian wrote: »

What diameter was the pipe ?

It is not in front of me now , but I think about 1-1/8", heavy wall aluminum.