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Binding & Purfling
http://www-.luthiersforum.com/forum/viewtopic.php?f=10122&t=19677		 Page 1 of 1
Author:  Andy Birko [ Sat Nov 15, 2008 4:58 pm ]
Post subject:  Binding & Purfling
So I'm building a stewmac 000 kit right now. It comes with this nasty white plastic binding that just grosses me out so, I found a nice curly maple board and am planning on making my own binding. Question is the purfling.

The kit came with two black and one white plastic strip for the purfling. I imagine that it won't look too bad because it's so thin so, can I mix the plastic purfling with wood binding, and if so, what glue would I use?

I was planning on using HHG for wood but that may not be possible because of the plastic. Any thoughts?
Author:  Brad T [ Sat Nov 15, 2008 5:38 pm ]
Post subject:  Re: Binding & Purfling
Yes, you can mix plasitc and wood. Duco cement from the hardware store should do the trick. Someone correct me if I am wrong. CA would be an option too, as long as you are sure to seal the channels with shellac or vinyl, as you have probably already read, along with a portion of the top. If you use CA and don't seal the channel and the area of the top around the channel, you will have a greenish tint in the area that you cannot get rid of, no matter how hard you try.
Author:  ChuckH [ Sat Nov 15, 2008 5:43 pm ]
Post subject:  Re: Binding & Purfling
Andy Birko wrote:
So I'm building a stewmac 000 kit right now. It comes with this nasty white plastic binding that just grosses me out so, I found a nice curly maple board and am planning on making my own binding. Question is the purfling.

The kit came with two black and one white plastic strip for the purfling. I imagine that it won't look too bad because it's so thin so, can I mix the plastic purfling with wood binding, and if so, what glue would I use?

I was planning on using HHG for wood but that may not be possible because of the plastic. Any thoughts?


Andy,
You sure the purfling is plastic. I guess you mean the purfling is one piece colored black on the outsides and white in the middle.

I thought my b/w/b purling was fiber when I got it, but looked at it with a magnifing glass and could definetly see pours in the wood. About your question with hhg, not sure if it will stick to plastic but know it will bond to glass real well.
Author:  Andy Birko [ Sat Nov 15, 2008 7:40 pm ]
Post subject:  Re: Binding & Purfling
ChuckH wrote:

You sure the purfling is plastic. I guess you mean the purfling is one piece colored black on the outsides and white in the middle.


Nope, it's three separate pieces of plastic or something plastic like - almost certain it's not fiber either.

Duco is what they recommend in the directions for the plastic binding and now that I think way back, that's what we used to make those balsa airplanes back in the day. I'll give that a try as I didn't like the way the CA worked for me last time I tried it for binding - It was probably just inexperience but the HHG worked so well I see no reason to try CA again.

p.s. to bend the binding I just built a pipe bender for about $16. $7 for a 2"x 6" steel "nipple" (2 inch OD welded pipe threaded on both ends) and a threaded cap and $9 for one of those 250w halogen portable work lights. Took the guts from the light and put them in the pipe and voila - worked like a charm on some old binding I had laying around.
Author:  Rod True [ Wed Nov 19, 2008 11:25 am ]
Post subject:  Re: Binding & Purfling
Hi Andy, yes you can mix wood and plastic. I use CA for gluing, and I fit the binding/purfling scheme into the channels first then just let the thin CA wick into the hairline seems between each. You do have to seal the top with shellac first though. My guess is though that you could use HHG. You could just nip off an inch or so (just make sure you have enough left for the body) and glue them together to see if the HHG will hold them together.

When bending your curly maple bindings, make sure you have something on the outside of the bend to support the wood. I use one of those stainless steel rulers you can get at the office supply store. Supporting the wood will help reduce the possibility of the wood snapping.
Author:  Michael Dale Payne [ Wed Nov 19, 2008 11:59 am ]
Post subject:  Re: Binding & Purfling
As stated earlier, most of the purfling LMI sends out with their kits are blackfish paper and maple sandwiches. It looks somewhat like plastic but is not and almost all adhesives work fine. Take a small sample and lay it in acetone. If it want to sofen and somewhat melt it is plastic (ABS)
Author:  Andy Birko [ Wed Nov 19, 2008 6:13 pm ]
Post subject:  Re: Binding & Purfling
Thanks for the replies folks. To clarify what's going on: the kit is stewmac 000. I bought some of the blackfish paper from LMI to make my own purflings for the last bandura I made and I'm pretty sure that this stuff is not it. If I can find some acetone, I'll test it. I just picked up some ultra thin CA and will try gluing the three individual strips together at one end to see how it holds. If it works, I'll use the thin CA to glue the wood bindings and plastic purflings.

On to the next question - I used my new binding fixture to cut the binding channels on the back using the stew-mac bearing guided bit and it worked really well. The question is for the top, does it mater which order you cut the binding and purfling channels. i.e. if I cut the binding channel first (the fixture's already got the right depth setting) will the bearing guide for the purfling be riding in the right spot, or is it required to cut the purfling channel first or will either way work fine?
Author:  Rod True [ Wed Nov 19, 2008 9:53 pm ]
Post subject:  Re: Binding & Purfling
Andy I don't have the stew mac binding bit kit but I've heard many others say that you have to cut the purfling channel first otherwise the bearing will ride in the binding channel and you'll cut the purfling channel to wide into the top.

So...

Purfling channel first, then the binding channel. You can step the purfling channel too if you want. Just set the depth for your purflings (or what ever depth you want just don't cut the top off the linings) and you can take a couple of passes changing the bearings to get to your desired width. Then set up to cut the binding channel.
Author:  Andy Birko [ Wed Nov 19, 2008 10:34 pm ]
Post subject:  Re: Binding & Purfling
Rod True wrote:
Andy I don't have the stew mac binding bit kit but I've heard many others say that you have to cut the purfling channel first otherwise the bearing will ride in the binding channel and you'll cut the purfling channel to wide into the top.

So...

Purfling channel first, then the binding channel.


Funny - that's what I was thinking first. Just to be safe I decided I'd re-watch the video that came with the kit to see what they recommend: it was binding first then purfling idunno . The binding bit comes with a spacer to offset the bearing to guarantee that it rides on the side, not the binding channel. They didn't say whether they used the spacer in the video however. On the other hand, maybe it would be better to ride in the binding channel. idunno idunno I'll figure it out somehow I'm sure...
Author:  Andy Birko [ Thu Nov 20, 2008 4:11 pm ]
Post subject:  Update
Mkay so I ended up doing the binding channel first mostly because I'm pretty lazy and didn't want to re-set the depth. I used the little spacer to bump the bearing down a little further and it worked just fine. By the looks of it, it would have worked fine even without the spacer.

As to gluing the bindings and purflings, I did the ole' tape in place using binding tape then wicked in ultra thin CA. This was somewhat problematic because it looks like the CA may have either softened the ABS binding or glued the sticky part of the tape to the top. It wasn't that big a deal to clean off but it was a pain that I didn't have to deal with when I did the back binding with HHG. After scraping off the residue from the tape I went back and wicked in CA where the tape was.

All's said and done though it looks pretty good now. There are a few spots where the bindings get a little thin but I suspect that if I don't point it out only luthiers will notice :lol: .
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