Thread: #1 Acoustic Build

Filling that is going to look pretty ugly however you do it
For the future ,scraping a small fillet on the inside edge of the binding strip helps it seat better.
Couple of options
-Do it again
-If you used titebond original, try to seat it better by working around with a clothes iron
-Cut a uniform channel around inside the binding and install a purfling line

I tried Alastair's suggestion of a trial filling on a test piece and it confirmed Jeff's assertion that it would be pretty ugly... Not sure how I'll proceed on this one just yet. I did think about a purfling strip as that would match the one I've fitted on the top but don't really know I'd cut the groove without damaging anything else around it.

Glued up the front side binding today and it came up quite a bit better. Still not perfect but a suitable result.

Attachment 153897Attachment 153898

If I was to remove the binding from the back to start again would it just be a matter of re-routing it to get it off or could this present further problems?

I guess it's good to find all these things during the first build, hopefully won't make the same stuff ups on the next one.

Steve, Thanks for the offer to ship me a bit, I found a supplier here by typing in metric forstner bits. Kinda looks like from your picture of the back binding that your channel isn't square to the sides. You might have to build or buy one of those fixtures that holds the router square to the side and you run the guitar against it. When I do use binding I prebend them by making simple molds out of scrap lumber, cover the mold with foil tape, then clamp the binding at one end, cover it with moistened paper and put a strap of thin stainless over that, then bend it over the mold and hit it with a heat gun to lock in the bend and remove the moisture. I drill several large holes in the sides of the molds so I can use simple spring clamps to hold it in place. I let it set a day or two in the mold and then glue it in. I've tried it without pre bending and had a heck of time. Good luckMike

You could use a manual purfling cutter (basically a blade with an adjustable guide) to cut for a uniform purfling line Then an improvised chisel to remove the waste.
Something like this
STEWMAC.COM : Ibex Purfling Cutter

Originally Posted by stevemc32

If I was to remove the binding from the back to start again would it just be a matter of re-routing it to get it off or could this present further problems?

Ive done this a few times.....my last classical had to have the back taken off a couple of times and I removed bindings/purfs with a Porter Cable trimmer mounted in a Luthiertools Williams style jig.

On occasions Ive also routed out an offending section of binding which has gaps and spliced in a replacement binding and purfling using a scarf joint. If you dont have purfling this will be a bit easier.

Ive never been happy using binding tape only for binding glue up jobs. These days I use binding tape but also wrap bias binding tape around the guitar as extra insurance....particularly in the waist area where gaps often seem to occur.

Steve, taking it out and doing it again should do the trick , the only thing is the router has to be the greatest tool there is to ruining a good day,I never run a mould without taking it in steps , usually three, unless it is a small mould like a bead moulding on the front of a shelf .

On table tops and cabinet moulds where I get paid if it looks good ,the first run will show up problem area's , like chip out's you did not notice that the bearing drops in to, or sensitive spots where the grain blows out, and lets you know if the router is set up right, the bit and fence and height adjustment are tight and not coming loose .
The second run double checks all of the first run and fine tunes the speed at which you are pushing the router , faster if burning is showing up, and you are left with the final cut knowing all this, and that the bitt not sruggling with a big bite.it comes up clean and ready to sand.

That's my blab on how I use a router for furniture , and for my build I would not use a router any other way .

I think if I were taking out that binding I would take a step or two in, in both directions, and leave .5 mm and give it a wipe with water and then warm it up with a heat gun, and the whole thing should peel out, if it didn't then I would do the final cut

I just got my top on Monday,a small problem there which I think I will get over,
and my back on Today, and I have problems with my back, big ones.got to do a post soon. Rob.

Thanks for the information and suggestions gentlemen. I took a few days off from the build and have decided that the back binding will have to come off.

I'm not confident of getting a good job of it by hand so I ordered one of the trimmer holding jigs that was mentioned. I thought about building one but for the time and costs involved it's just not worth the effort.

So the plan is to remove the old binding and then route an extra ledge on the back for a purfling strip that should remove the evidence of my previous poor routing technique. The binding strips I used are 2mm x 10mm strips of hardwood and were definitely pre-bent to the outline of the back. I think one of the problems was that the strips had not been pre-bent to the curvature of the back as this involves a bend through the 10mm width of the strip. I might try this on the next one but do not expect to get a useful result.

Martin, I could not find any references to bias binding tape. Could you give some further information on this?

Rob, you picked me in one! I routed the top binding ledges in 3 or 4 passes to get to the final depths but since I had to the trimmer set for final dimensions just went straight ahead and did the back in one go... Thanks for the tips.

Originally Posted by stevemc32

Martin, I could not find any references to bias binding tape. Could you give some further information on this?

Should be available from any dress making shop. Try and get the widest stuff you can...I think the stuff I'm using is 50mm wide. Its not cheap but can be re-used.

This is the stuff:

1" 25mm White Cotton Bias Binding 33 Metres Dressmaking (eBay item 370427393321 end time 01-Dec-10 09:12:42 AEDST) : Crafts

An alternative is macrame rope.

Cheers Martin

Thanks Martin. I've got some bias binding on the way.

My trimmer jig should arrive tomorrow so I've been preparing another set of bindings for the back of the guitar today. Nothing too exciting.

Attachment 154252

Finished off re-routing the back binding ledges today with some minor difficulties.

There were a number of areas evident where the binding had not been glued in contact with the side wall of the original ledge. Unfortunately this lead to some bad tearout in one area where the binding strip came away and took a chunk from the side with it... Don't think it's recoverable but I'll try looking around the shed for the piece that came out and see if I can glue it back in there.

Attachment 154530

Waiting for my bias binding tape to arrive before I glue up again but seems I've still got a major problem with these bindings. Actually, the major problem is that the curvature of the back is probably quite a bit larger than it should have been. This problem showed up when I noticed the gap between the neck block and the back after gluing the back onto the sides. I didn't think it would cause any serious troubles at that stage but it's turned into a pain in the butt.

The problem is that when I force the binding to follow the curvature of the back it buckles outward at the top of the binding in the waist area and takes quite a bit of effort to twist it back square with the sides. I tried a couple of quick clamps on it to hold it square and looks like this may be the only solution.

Attachment 154531

The only other idea I can think of is maybe to soak the waist area of the binding in water then heat it up with a heat gun and refit it to the side of the guitar and let it dry off. Don't know if this would be effective and not sure I want to clamp a hot wet piece of binding up to the side of the guitar either.

Had another idea to use the molds instead of the side of the guitar to try and shape the binding. So first I traced the curvature of the back onto the inside of the mold, then wet the binding and heated it up on the iron a number times before clamping it into the mold aligned with the shape required. Leave it overnight and see how it turns out.

Attachment 154553

Another quick question, is there any reason not to glue in the purfling strip first prior to gluing in the binding? It will take longer to complete but seems like it would be a little bit easier option than fumbling with them both together and covered with glue?

Attachment 154554

The short answer is "yes", fit the purfling first.

Ive tried all manner of things to get binding to sit perfectly and the only one that has worked is spending a long time making sure the binding is bent perfectly before sticking it on. I dont make moulds so this is when I find out how asymmetrical my work actually is. I dont remember what your binding material is Steve but cutting and patching works with Ebony if you are really careful and sneaky. You can also make a Gamel type cutter from a couple of pieces of dowel and a sharp blade which will square up the waist binding ledge. I'll post a photo of my rough one if you want.

Originally Posted by stevemc32

Another quick question, is there any reason not to glue in the purfling strip first prior to gluing in the binding? It will take longer to complete but seems like it would be a little bit easier option than fumbling with them both together and covered with glue?

Attachment 154554

I was thinking the same thing with my binding Steve, I noticed that ALS sell a teflon strip for helping out for such a two stage glue up,

Guitar Parts from Australian Luthiers Supplies - Parts and materials for guitars, basses, mandolins and violins, replacement hardware including bridges and machine heads, wood for tops, backs & sides, necks and fingerboards, tuners, bridges and other

cheers Rob
I have to learn how to make a link come under one word yet

Would love to see a photo of your cutter Sebastiaan. Much appreciated. The bindings I'm using are some unspecified Australian hardwood that has spent the last 45 years or so as a Sydney house. Having cleaned up the back one before stripping it off I found it actually matches the back and sides quite pleasantly.

Thanks for the link Rob, it's an interesting idea there gluing that strip in then ripping it out to form an inlay channel. I'd like to try a shell inlay maybe on the next one so I'll keep that in mind.

Originally Posted by jeffhigh

For the future ,scraping a small fillet on the inside edge of the binding strip helps it seat better.

Jeff, do you mean chamfering the inside corner of the binding strip. I could see how this might help to overcome some problems with a binding ledge that is not perfectly square.