Official Luthiers Forum!

Hello all--
So I'm working on my third LS Redwood topped guitar. The one thing that I found constant with all 3 tops was they are prone to splintering when using a router on them. Even cutting the out line of the guitar with my ban saw caused considerable splintering along the cut edge. So this brings me to my question. I'm fearing that when I cut the purfling ledge, the top will splinter along the cut. The only thing I can think to help would be to buy a manual binding cutting tool such as the Purfling Groove Cutter that Martin or Stewmac sells, and precut a line into the top (BEFORE) taking it to the binding machine. Just for the record, I have givin the top a wash coat of shellac to help. I often have wondered if this is making it worse?


---confused --
Lance

_________________
Support the OLF! Bookmark our STEWMAC link Today!
Lance@LuthiersForum.com

Maybe the shellac is making it worse. I just used a redwood top on my last guitar and I don’t really remember it being that bad. I don’t have a binding machine though. I use a dremel and work toward the final depth cutting deeper with each pass I make.

Colby - IM really thinking the shellac is hardning the top, and making it britle.

_________________
Support the OLF! Bookmark our STEWMAC link Today!
Lance@LuthiersForum.com

Lance,

I can thoroughly recommend using a purfling groove cutter before routing. I now use it before all of my purfling and binding cuts. However it's only any good once you have a regular edge for it to index off. so you'd still need to flush cut the top once it's attached. That and of course care with the usual climb cuts, even when using the band saw for roughing out the top. As usual if using a new tool, practice on some scrap

Colin

_________________
I don't believe in anything, I simply make use of a set of reasonable working hypotheses.

Lance, I've only done one redwood top, but I don't remember any problems with it splintering on me.

However, I didn't shellac it before cutting the binding channels. Maybe that is your problem.

_________________
Dave Rector
Rector Guitars

Lance, I have had this problem with cedar this week. The only thought toward a solution was to shellac the top, which you've done. And... change to a spiral downcut bit, I was using a carbide double edge straight.

The straight also gives fuzz cuts in rosewood along the crossgrain areas. So, worth a try.

Lance,

If you score the line first with an edge tool you won't have this problem. A well sharpened gramil or purfling cutter (you really could make one quite easily if you don't want to spend the money) will make these worries go away fast.

Sharp bits too.

Best wishes,
Joshua

_________________
Instagram: @jfrenchluthier
Web: https://www.jfrenchguitars.com/

Lance I think the shellac actually does help. You can make a really shallow first cut just breaking the surface about 1/32" or less. Make sure to cut with the grain of the wood and not against it. Thats when most splintering occurs. Each half of the top should have four travel directions. Two on the lower bout and two on the upper bout. I know it's a pain but it is worth the trouble.

_________________
Beautiful and unusual tone woods at a reasonable price.
http://www.rctonewoods.com/RCT_Store
The Zootman
1109 Military Rd.
Kenmore, NY 14217
(716) 874-1498

And only route "down hill."

[QUOTE=Bob Steidl] And only route "down hill."[/QUOTE]

"Splain please"

Erlewine in his guitar building video shows what Cefalu is alluding to, four cuts per side. This may be another "oh, so they really meant it" moments.....

I believe it was Roy Noble who installed a reversing switch on his laminate trimmer so you are always routing "into" the grain. You would also need a bit with a reversible cutter obviously,I'm pretty sure Amana makes one.

I've done lots of redwood tops on my binding router, and I never have
problems with redwood splitting or chipping. I use the LS a lot too and
no problems. I do use a spiral bit for the most part though. Here are
some pics of a guitar I just bound. LS Redwood/Madagascar No
problems at all.

_________________
John Mayes
http://www.mayesluthier.com

Redwood is really brittle and the LS wood is especially so!

Make very sure that your cutter is clean and sharp, and that your power
tool is running well -- up to speed, powerful enough, and without
bearing slop. Scoring the grain with a blade would be a good move, but I
haven't found it necessary.

I shellac the edges, rout fairly slowly (1"/second), with an uphill cut. Most
importantly, I don't attempt to rout the whole purfling depth (Or is it
width?) in one pass. I freehand the cut, keeping the guide clear of the
body by a little bit, then go back and finish with the guide bearing riding
against the sides. If you wanted to, you could rout with a larger guide
bearing, then switch to the smaller, final size for the last cut.

And don't even think about using CA glue! It will almost always discolor
the end grain despite all efforts to seal it.

I agree with Rick. I very frequently use the same method. I should have mentioned the sharp bit too.

_________________
Beautiful and unusual tone woods at a reasonable price.
http://www.rctonewoods.com/RCT_Store
The Zootman
1109 Military Rd.
Kenmore, NY 14217
(716) 874-1498

Strange cause I've never had a problem with it chipping at all, and I take it
all in one pass (well I cut the binding ledge first so technically some of the
purfling cut is taken out).

But my bits are sharp and I do move slow. I climb cut however.... So
many different ways.

_________________
John Mayes
http://www.mayesluthier.com

Lance, I've made a tool for scoring the top before flush cutting the top. I'll put up a picture as soon as my wife tells me where the camera's USB cable is hidden. It is simple enough to make. Take a block of wood. Put in a 3/4" wide X 3/4" in deep notch in the side of the block.
Superglue an exacto blade so that it overhands the notch.

To use the tool run the block along the side of the guitar with the blade scoring the top. The top overhand slide into the notch.

All the above have described the best way to work redwood tops. Use a spiral downshear bit to trim the edge flush to the sides, shellac the top edge, do the multiple pass method of cutting (directional and depth, if you wish). I'm using the LMI cutter with the wide assortment of bearings. And I clean the cutter edges after every few cuts, especially when cutting the more resinous/oily woods. After all is cut and clean, re-shellac to seal the exposed grain edges to reduce as much as possible the chance of glue wicking into the end grain of the redwood
I have used a lot of the "Carter" redwood since 1998...LS,TA,TB,ST & FA sets. I have had minimal problems. I cut the binding channel first, then move in and cut the purfling channel, usually only about .050-.060" depth, depending on the purfle material. I use the binding cutting "machine" with the ball bearing vertical drawer glides and I have a counter weight attached to reduce the weight of the router to about 1 lb as it rests on the instrument.

Well I must have been having a senior moment. My previous post is how I trim the top overhang to the sides. For binding I climb cut and keep the guide clear of the body like Rick stated which leaves enough for a cleanup pass. Bruce I believe what Bob S. is referring to is the same as a climp cut. Moving with the cutter rotation instead of into it.

_________________
Beautiful and unusual tone woods at a reasonable price.
http://www.rctonewoods.com/RCT_Store
The Zootman
1109 Military Rd.
Kenmore, NY 14217
(716) 874-1498

For my first LS top, I started the cut at the top under the neck joint and progressed clock wise all the way around the body, no problems, matter of fact this is how Ive done all my tops. But this top in particular is so dang brittle that is just wants to splinter at the drop of a hat! Ill try smaller cuts and more of them -- Thanks guys!

_________________
Support the OLF! Bookmark our STEWMAC link Today!
Lance@LuthiersForum.com

[QUOTE=Bobc] Bruce I believe what Bob S. is referring to is the same as a climp cut. Moving with the cutter rotation instead of into it.[/QUOTE]

Yessir.

Well I'll be! And to think I thought I knew it all

Thank'ye guys! Once again, I am enlightened here at the OLF..

_________________
Support the OLF! Bookmark our STEWMAC link Today!
Lance@LuthiersForum.com

I've used the stewmac note as a guide and it seems to work fine. At least it has on the few guitars that I have done. Haven't tried my redwood yet so we'll see.

http://www.stewmac.com/freeinfo/I-1298.html

http://www.stewmac.com/freeinfo/I-1298.html
This is what I use and it seems to work though I've
not tried Redwood yet.

Keith. Interesting article, thanks.

So Bob S. what software do you use to make those neat little drawings? I'd like to be able to do that too.
Sure explains what your trying to say.

_________________
Beautiful and unusual tone woods at a reasonable price.
http://www.rctonewoods.com/RCT_Store
The Zootman
1109 Military Rd.
Kenmore, NY 14217
(716) 874-1498