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drop top / binding question


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Hi All,

I've done a search on the above subjects but couldn't find the information I needed (so please don't shoot me down!).

My first quesion is What is the vacuum method Scott R. uses for applying his drop tops, Are there any links to detail how this is done?

secondly, is a 7mm burl maple top too thick to bend?

And lastly, if I wanted to apply a binding to the body, how would I rout out the arm contour section to accept the binding. Is the binding material flexible enough to bend 'downwards and around the arm contour easily?

Thanks

Genbloke

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The vacuum method is to place the assembled, glued parts in a large pouch and suck the air out. This presses the parts together and is a great way to get it to conform to curves. However the gear required is specialized and expensive and the setup can be a little tricky. If you have to ask, that means you probably can't do it. Maybe you could find a woodshop that would let you use theirs (rental?), but if it is your first guitar, try to keep it simple.

7mm is not too thick. Be sure your burl is completely dried and stable before you begin, it's not the most stable to begin with.

I don't think any plastic bindings will bend as much as you want. Steamed woods get pretty flexible, but again, if this is a first project...

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Thanks for the reply DannoG.

I've just found the vacuum veenering tutorial on this project guitar site. I think this is beyond me. I'll go for the standard 'plenty of clamps technique.

Is this correct?- Spay water on the surface of the wood, steam and then bend slowly a bit ot a time(avoiding the bookmatch join)? Do I need to wet / steam both sides of the wood or just the outer face that will get the main stress of the bending?

Thanks

Genbloke

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I've done several guitars using Scott's info as a guide. The one thing I do differently is I don't glue the top on first (I think Scott glues and waits for it to cure before bending the arm rest portion?). I get the top nice and flexible first, apply glue, attach it to the body (I usually use pins to locate it correctly) and then apply more heat to the arm rest portion and bend until it meets the body. I also use Titebond Extend (usually) since it allows a bit more time for setting up and supposedly handles joint creeping better than other Titebond products. I don't think this is really needed but it's what I use. The main reason I use the Extend type is for the additional setup time it allows.

I'll tell you now that the process is very nerve racking on your first guitar. Have the spool clamps (or whatever clamps you're going to use) ready to go and have them adjusted close to the right size so you don't have to spend time cranking them up or down. Have your pieces of cardboard or whatever you are using to protect the wood from the clamps ready to go also. I like to save as much time as possible during this so that I can spend more time examining how it's going instead of searching for tools,...

Plan the whole thing out and do a "dry" walk-through. It will help settle your nerves and it might turn up some things you may have forgotten. I don't mean to spook you - just want to help point out the importance of being prepared.

I hope it goes well for you. Scott's info helped me a ton when I did my first one.

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Cheers Daveq,

That's cleared things up. In regards to using pins- I've always wondered how to align the join in the bookmatched top to the join on the 2 piece body, now I know :D.

The thought of cracking my lovely piece of burl maple does scare me a bit (hence all these questions!)

How much time do you normally get when working with Titebond/ Titebond Extend?

Thanks again

Genbloke

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Extra caution is required here, as the burl is not NEARLY as stable as a piece of flame or even quilted maple. On my current project I have a spalted top that is 3/8" thick (9.5 mm). I followed Daveq's approach, steamed and bent the top first, it took a lot of time to bend it but I eventually got it to fit the forearm contour. I did several dry runs first, then went for it. All went well, clamped up nicely, but apparently the wood around the contour was not dry, and when it did dry out (as the glue dried) it cracked right along the ridge of the forearm contour (and across the grain :D ).

The crack was repaired with epoxy nicely, and now it just looks like a bit of the spalt. Probably would be the same situation with burl. You may want to thin the top at the forearm contour before starting, that what I wish I'd done (but my piece was thicker to start...).

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You can get the binding to bend around the forearm contour by either heating it with a blow-dryer or dipping it into hot (just barely boiling) water. While the binding is still soft, press it into the binding channel, tape it down, then let it cool for ~30 minutes. It should fit the bend nicely.

This applies strictly to binding that is 3/16" thick or less; if it is any larger than that, you may need to cut notches in the bottom edge of the binding in order to take up the bend.

Edited by erikbojerik
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erikbojerik,

Thanks for the replies. I've decided to go against doing a binding 'cos this is my 1st guitar build (doing the drop top is going to be a big challenge in itself!)

To round up, after the reading the above replies (thanks everyone) and some more searches, the best method (when not using a vac bag) to bend a drop top is:

1. Dampen the surface of the wood (using de-ionised water to prevent minerals in tap water staining the wood) and leave it for a few minutes.

2. Steam the wood until pliable (avoiding the bookmatch join).

3. Apply glue to the body and put the top on it, using 'pins' to locate the bookmatch join correctly

3. Using more steam, bend the wood over slowly using LOADS of clamps.

4. Leave for several days (or weeks) to allow the glue to set.

Does this sound good? Has anyone tried using a wallpaper stripper like one of these to generate the steam?:

Wallpaper Steamer

Also how 'bendy' should 7mm thick burl maple be before attempting to bend it?

Thanks Again

Genbloke

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1.  Dampen the surface of the wood (using de-ionised water to prevent minerals in tap water staining the wood) and leave it for a few minutes.

2.  Steam the wood until pliable (avoiding the bookmatch join).

At this point, I would clamp the top down just like you were going to glue it, only with no glue. Let it dry for a week. Then when you un-clamp it the top will stay bent. Apply the glue quick-like, then clamp it all down again.

3. Apply glue to the body and put the top on it, using 'pins' to locate the bookmatch join correctly

3. Using more steam, bend the wood over slowly using LOADS of clamps.

4. Leave for several days (or weeks) to allow the glue to set.

Once glued, I left mine for a week before removing the clamps.

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