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Oh the joys of scraping binding. Am I the only one breaking out in a flop sweat scraping like a madman?

A question - Until now I’ve been putting on binding that is a bit proud and then scraping back. I was leaving the extra so I had some fudge factor in case it got thin in a spot I could maybe still save it. At least that is the idea. I was also using titebond until the last few instruments. I’m now using CA which allows me to get everything set the way I want it before committing to the glue.

My woodworking has steadily improved over time and I believe I can now have it be flush right off the bat and save myself some of the scraping.

Do you guys like to have the binding channel such that it’s flush or a little shallow so the binding is proud?

Brad


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I prefer flush with the sides and a little proud on the top and back. It’s just the pattern I’ve fallen into. A benefit of flush to very slightly recessed binding is that if you scrape the side down to the binding the binding will remain the same thickness, when viewed from the top, all the way around since you sand the sides down and don’t really touch the binding, but you have a lot more sanding to do.

My tough spot is always the rounded cutaway where I can never get it totally uniform due to the complex angles involved, but each one keeps getting better.

Hi Brad,

I’m a CA guy too. I like it because I can install the bindings and scrape back in about 4-5 hours. As for the ledges, I’m still leaving my bindings and purflings proud of the top and back and setting the cutting the side bindings flush. I made an oval disk that screws to the bottom of a StewMac dermal base, and using an 1/8” bit flush cut the top and back bindings nearly flush. I can post a picture of the setup when I get home. I’m currently in Portland, OR for a week of hangin out with Charles Fox hopefully learning stuff.

M

One more vote for CA, one more person who tries to get the side flush but lets the top stand proud by just a hair (couple of thousands). My purfling lines might be proud of that. My thinking is that the top is at a slight angle and I want to scrape the binding to match, and I want to put just a slight radius on it so I can run around with the scraper (often a box cutter blade) and do all of that together.

From your “flop sweat” statement something doesn’t seem right.i always leave a little proud everywhere then scrape back, but with a sharp scraper it should peel like butter on the sides.

For the top and back i CAREFULLY use a small plane to slice it down to close and then scrape perfect.


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Enjoy my friend. What a treat to be there.

Pics would be great.


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I aim to leave the binding just a couple thousandths proud on the sides. It's a lot less work to bring the binding down to the sides than the sides down to the binding. I leave the top edge of the binding/purfling proud to allow for the differences in the binding channel depth around the body cause by the curvature of the back and top. I can't say I work up a sweat leveling the binding. I use a scraper as much as possible but some binding woods I've used tended to scallop or ripple with a scraper (even a sharp one) so those were finished off by sanding the last bit until flush.

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I bind with plastic - no big deal scraping plastic. I try to make it flush with the sides and a little proud of the top and bottom.

From the builder's guide we employ in the shop:



It seems as though one advantage of fitting the binding slightly proud of the channels is that the binding itself need not be perfectly trued prior to installation - slight chamfer or round-over on the show edges ends up being scraped away. With the recent cellulose nitrate binding material work we've been doing on new projects and repairs, I've noticed the condition of the edges on plastic binding stock can vary quite a bit. Stock purchased from one supplier has uniform, true dimensions, while another supplier's material has at least one fresh-from-the-saw edge; truing up those ragged edges takes time, as each strip must be run through a scraper-based binding jointer jig.

One piece of instruction I received in the first few months here applies to scrape-back: prepare the card scraper for the intended work. An coarse, aggressive edge straight off the file works better for the rough work of scraping back rock-hard bits of CA or dried fish glue, while a fine, stoned edge with a delicate burr will provide the close-to-finish-ready surface desired once all that glue has been cleared. A dull scraper will tend to cut only on the softer material present, making generation of a uniform surface difficult, so frequent trips to the sharpening bench to keep the tool cutting well seems like time well spent.

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A constellation only takes shape when one maps the whole.
- Beth Brower

I think I would rather sand and scrape the sides ever so slightly to come flush to the binding then the other way round. I strive real hard to get the binding to be the same thickens along its whole length and installing the binding slightly proud and scraping back almost always causes unevenness.

If memory serves, Mr. John Hall also mentioned milling his binding channels just a bit deeper than his binding thickness and sanding the sides down to the binding, although I believe he also may have mentioned that the binding is applied proud of the top and back for obvious reasons.

It may be a matter of individual technique, but on the top and back, we safe one end of the card scraper with 3M blue tape and take the binding down using passes at two or more skew angles to even out the cutting action and avoid creating humps and bumps in the dressed binding. For sides, hitting the 3"-4" of body wood versus cutting just the 3/8" or so of binding dramatically slows the cutting action such that we are alerted to the flushing of body wood and binding. The shellac sealer applied prior to milling the binding channels and prior to a CA binding job also helps with visualizing the cut, and I'll use chalk or pencil witness lines where necessary when things get close and I'm working with sub-thousandths cuts to bring things flush.

One other concern on prep of the channels for accurate binding width and depth:

Using binding jigs that guide depth based on the top or back (while keeping the bit axis vertical), the channel above the waist on the back of the guitar will progressively shallow as the slope of the back changes due to the change in contact point location versus the center of the bit. A dreadnaught body will see something like a 6 degree slope on the back at the neck block, versus closer to 1.5 degrees on the top, so the channel depth of the back binding above the waist may need to be deepened to show consistent binding depth after scrape-back.

We see this variation in depth on some factory and custom instruments, with anywhere up to a 0.015" difference in depth from the lower bout to neck block. A sharp wheel-style cutting gauge such as the Tite-Mark does a nice job of cleaning this up, and we finish the job by back-beveling the lower edge of the binding about 2/3rds width to match up and provide a nice, tight fit.

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A constellation only takes shape when one maps the whole.
- Beth Brower

I've always put the bindings on proud on the sides, and scraped them back. I can't see how it would be less work to scrape back the larger area of the sides and keep them level: I suppose it's a different thing if you use a drum sander. Scraping back bindings has gotten easier since I switched to mostly using hard scrapers: they do a smoother job on figured wood, for one thing, and it's much easier to use a hard scraper on the pull stroke or one-handed. By keeping pressure right over the binding, and allowing the free end to float on the side without actually cutting you can just skin the binding down without removing material from the side.

You must get the side shape right and the curves fair, as Woodie says, before you do any routing for the binding/purfling ledges. A binding routing setup that keeps the router axis parallel to the sides by whatever means is also a must, if you're going to end up with a uniform width of binding on the top and back surfaces. The alternative if you don't want to rig up one of those is to carefully scribe the top/back and sides with a marking gauge, rout the ledges as close top that as possible without going over the line, and then dress up with files, chisels and knives. The big problem area, of course, is around the upper bout on the back, where the combination of taper and arch cause the router to angle in if the base guides on back.

If you do laminated sides, leaving the binding proud and scraping it flush (rather than blocking the sides heavily) can help avoid "sand throughs" and thin spots in the outer veneer. Of course this depends on laminating the sides without humps and bumps. I usually wind up checking the binding rebate with a short scrap of binding and making corrections to the depth with a file. I am perhaps less fastidious than some about binding - 0.015" variation in depth from top to bottom wouldn't bother me, and although I knock off the inside corner to help fitting the binding, I try not to thin it any more than necessary. Binding work is something the more you do, the more particular you become and see areas for improvement. But I don't get bogged down seeking perfection.

As someone who just spent this morning scraping binding all I can say is:

Proud sides or proud binding, I hate them all! Binding is easily my least favorite aspect of building, from routing the channel to glueing in the binding to scraping them flush. Plain just hate it!

As I learned here on this forum, sanding the inside edge of the binding seems to allow better fit.....

I totally agree that the routing has to be accomplished accurately as possible. I do set my binding at .0625 and set my depth at .065 when I rout. This allows a touch of glue. I can then lightly sand the sides to the binding fairly quickly. Your end result is only as good as the prep. I stopped scraping binding to size watching how Martin did it.
A few minutes of accurate prep will save a lot of time in the end and give you a nice even binding appearance. While I do it opposite of Mr Carruth I bet he isn't scraping .020 thou.
learning to use the tools properly is also very much a necessity . Rolling the edges or thinning the binding gives an uneven appearance . It takes time to learn all the techniques to do this properly.

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John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

If you can get the binding close to "flush" everywhere, then scraping the binding a little bit one place and sanding the side a little bit another should give a decent result.

I think doing the binding is a seriously underestimated task, and frustration sets in when the magnitude of the task sets in. Today I finished scraping/sanding the binding on my current project. I didn't keep a diary, but I suspect I spent as much time on the binding as in assembling the box (making the rim, assembling the rim, assembling rim to soundboard and back). I also found good results in checking any work done the morning after it was originally done, and finishing what was overlooked or passed off as all right. There's usually a few hours spent in doing that.

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Peter Havriluk

If scraping the binding is consuming that sort of time across multiple instruments, I have to believe that you would benefit from spending some time in another luthier's shop to see if your process or tool use might be responsible for your issues with scrape-out. Scraper prep and use is such a core skill for builders and repair people that investing a day or two in pursuit of improving those skills is warranted. A couple phone calls, a few hours of driving, and the tendering of a bottle or two of something Scottish and old enough to vote might get you headed in the right direction.

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A constellation only takes shape when one maps the whole.
- Beth Brower

How many beer job do you estimate on that one Peter?

Actually, John, I often do scrape as much as .020" (.5 mm) off the binding. I guess I'm just a glutton for punishment. OTOH, with a sharp hard scraper it's not as much of a chore as all that.

I'm building two guitars for a guy now who wanted Ivoriod binding. I've never used plastic binding before and it's easier on all accounts. Easy to install and it scrapes like butter. It looks pretty good too actually.

I need to learn how to sharpen my Carruth hard scraper. I do have a thick card scraper that I use regularly and I think that is key in getting it done fast.

The Trogi (sp?) is probably a wonderful device for such things.

Hi Alan
I am surprised
I do all my bindings wood or plastic at .0625 and rout a channel about .065 to .070. Allowing a touch of glue I have a light sanding and I am done. Like you I used to scrape but after watching martin I went the way they do it. It takes me less than an hour and I am done.
I do break all inside corners , machinists trick instilled after 20 yrs.

_________________
John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

I think it depends on the glue used too. I've learned over the years that if I am using Titebond or Fish then I make the rout significantly deeper then the binding. I've never actually measured it but I thing the water base glue swells the wood binding up. If I am using CA then I get as close as possible, set everything down with tape and inject the glue.