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I have noticed some saw toothed edges, in the rosette channels, on the last several Lutz tops. I am using a PC lam router in a MicroFence. Sealed the surface first with shellac and allowed to dry for several hours. I have also tried it without shellac with identical results. Used [NEW] up cut and down cut carbide spiral bits with the same results. I have not had these issues with any other Spruces, Cedar or Redwood. Anyone else notice this on Lutz?

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tim...
http://www.mcknightguitars.com

Layout your rosette cuts with circle cutter before using your router. A shape blade gives you a line to work to and prevents tear out and feathering of the end grain lines.

See this website for a great tool for this purpose. http://www.hobbico.com/tools/hcar0230.html

I also use a blade before I cutting the rebate for binding on the top.

Steve

Tim do yourself a favour and make one of these, this is one I copied from Joshua, I used it to cut the rosette channel on my last classical. I would not even consider routing a rosette channel now without first defining the edges with one of these. Bit like using a gramil to prevent tearout on the binding channel.



Colin

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

Yes Lutz seems to have hairier edges then other spruces but I only see this on the binding channels. With my wimpy Dremel and Stew-Mac router base with 1/8" spiral down-cut bit the rosette channels are very sharp with no stringiness or tear-out. I don't coat the area with shellac or scribe the outer edges either.

I do take many shallow and small passes though sneaking up on the desired channel size. I wonder if the bit diameter makes a difference - perhaps smaller is better here?

I have used 1/8" and 1/16" up and down cut bits, left and right hand cuts and it makes no difference. Tried varying the depth of cut and the last inner and outer cuts by only a few thou. It makes no difference and it seems confined ... only ... to Lutz. Thanks for the suggestions though.

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tim...
http://www.mcknightguitars.com

I have been using a laminate trimmer with a 1/4" bit in it for cutting both the rosettes and the binding channels. I have noticed the stringy uncut hairs left over after cutting the channels, but a quick swipe with a small sanding block usually cleans it all off. Are you experiencing anything different than the hairy edges?

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Reguards,

Ken H

Yes, in addition to the fine surface hairs the edge grain in two opposing places in the rosette channels are not cut smoothly. In a magnifying glass the edge grain looks jagged like saw teeth. After the rosette is inlayed and scraped or flush sanded the black fiber or died black maple trim rings will fold over in these "saw teeth" marks and the edge looks ragged. I am used to seeing the edge be crisp and clean (as are all other Spruces, Cedar or Redwood) but not the case with Lutz.

The tops are several years old, dry, welll seasoned and have been stored in a controlled wood room.

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tim...
http://www.mcknightguitars.com

Hmm - It could be the latest McKnight innovation. -- Serrated edged rosettes..

I like the idea of a scribed initial cut.

Another thought - when your bit gets small, like the 1/16", the speed of the cutter is substantially reduced. I don't mean the RPM, but the velocity of the cutter surface. If you don't have a very fast router/trimmer, that could be an issued. Can you use a 1/4" or larger tool?
Is it HSS steel or carbide. HSS can get dull pretty fast, especially with a small tool. Have you tried a carbide bit?

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"An adventure is only an inconvenience rightly considered. An inconvenience is an adventure wrongly considered." G. K. Chesterton.

I found Lutz really got furry when I was routing for my inlay. I precut all my edges, then used a spiral down cutter to finish up.

Try glue sizing the top first. Honestly.

http://www.nkforsterguitars.com

I find I get a cleaner cut if I rotate the router clockwise for the inner cut & counter clockwise for the outer. I also go around really slowly, taking just a few thou at at time once I'm close to the final diameter. On coarser grained wood I go even slower, taking as much as two minutes to cut the full circle.
Lately I've been using a four flute down spiral bit made by Samona. Not normally considered the best name in tools, but these bits work very well. It seems the smaller the bit, the smoother the cut is. I've dedicated the 3/16" one for rosettes. It also helps to clean the bit thoroughly before you start. I use acetone or lacquer thinners & a fine brass brush.
Still, once in a while I get those serrations. Usually on the outer cut, around the five O-clock & eleven O-clock positions.
The tearing seems to happen only near the surface. I am leaving my tops a bit thick these days & take them to final thickness after the rosette is installed. Any roughness disappears once i reach the final thickness.
If I'm installing a ring of shell, I rout the channel for it after thicknessing.
One of these days, I'm gonna build a tool like Colin's. Probably save time & do a nicer job!

Tim;
I've not had this problem.
I use a Hitachi router with a down cut bit .
The router has a speed adjustment-I set it on the fastest speed!
My base for routing roses is birch plywood (3/4")with a steel insert (50mmX50mm) with a hole drilled in it to fit the pin on my trammel point attachment-so there is no round out of the router.
I go slow -cedar tears more than lutz in my experience.

mike

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Mike Collins

Tim... I think the reason you are having issues with tearout may have more to do with the top your working with than it does with tools and technique, I've used Lutz on 10 or 12 guitars and never had the problem you describe. One of the things I noticed about the Lutz was the fact that binding tape NEVER pulled fibers out of the tops when taking off the tape. NOW... on my most recent Lutz guitar I had the same serrated edges your talking about on the ledges and rosette. AND each and every piece of binding tape pulled up huge chucks out of the top if I wasn't careful. That top was clearly different from others I've used.

I'm curious if the issues we're seeing is isolated to one particular tree, That would explain why so many others here have not reported similar problems.

long

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"No man ever steps in the same river twice, for it's not the same river and he's not the same man.” -Heraclitus of Ephesus

Tim,

I don't really know what to say here except that thanks for the input and I hear ya. This is the first I have heard of this issue, and you know that there are a few thousand sets from me out there now. Bob's observation has truth to it, every tree is indeed different. But, Tim you have sets from way back in the days when I received some billets from Mario to very recent harvests. So I think that it is not that likely that yours and Bob's are from the same tree, although it is possible! I personally have not inlaid many tops myself yet but I frequently get pictures of guitars built from some of my customers and no one has reported this problem. I used a 3/32 (I think) downcut spiral that I got from Stew Mac and had no issues on one of the sets that I processed in 2004. Sure hope you figure it out!! I can say though that when I process tops I like to see that long fibre on the edge when I saw, it tells me that the runout is minimal and that there is a LONG fibre in this wood which I think is quite desirable for both sound and structure.

Shane

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Canada

You may be on to something here Shane... The top I had trouble with did indeed originate with Mario. I got it second-hand from one of the swap-meets.

long

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"No man ever steps in the same river twice, for it's not the same river and he's not the same man.” -Heraclitus of Ephesus

Shane,
Daniel M described the problem that I am having. I did not want to specify where the saw toothed edges are appearing and just set back and see if anyone else mentioned it. Five O-clock and eleven O-clock are the exact same areas where mine are tearing out.

Shane, I have 4 different batches of Lutz from you and unfortunately I can't isolate the exact batches. I know some of the tops are from the most recent batch and a couple are from the oldest batch many moons ago. I wish I would have paid more attention to the edge grain. I don't think it is run out related because all of your tops have been VERY consistant with no run out, thank you very much

I ordered some new down cut bits today from two different sources than I have used before so we will see if that has any bearing on the matter. What baffles me most is I don't have this problem with other species with the same exact tools and set up. I have a rotary style drill press cutter around here somewhere so I might get it out and see if that makes any difference.

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tim...
http://www.mcknightguitars.com

Take that advice and you'll never deal with this problem again. Its a cheap, simple and elegant solution. We could spend weeks deciding if its the bit, rpms, direction of cut or something weird with the tree. Or you could make one of these, have the best tool for the job and never have to worry about this again.

Sometimes simple hand tools are the best solution, yet still overlooked. Try it, you won't regret it.

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

This is the simple cheap hand tool I recommended and you don't have to make it

But it's plastic!

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Waddy

Photobucket Build Album Library

Sound Clips of most of my guitars

There is definately differences depending on the tree the wood came from. The Lutzi I have is all from Mario, and he names each tree, so I know what tree a bolt came from. What he calls 70203, 70203 #2, curly bear, Wonderwood, Iron Spruce, Red Bear, White Gold, Furry Bear and so on and so forth are all from different trees. I have noticed differences in density, hardness, fibers depending on the tree. I thought the naming was goofy when I first bought from Mario, but it may prove very helpful. I will set up some router tests and see if I can find a corrilation.

This top was 70203 #2, and like I mentioned, it was furry when I routed for my inlay , but that is not uncommon with most top woods. The rosette channel was cut with a spiral down cutter using my Hitachi router and and locating pin in the base. The rosette channel didn't seem to give me any trouble.


Bob, if the set you had trouble with was one from me at one of the swaps, shoot me a PM and I will look back at my records and see what type it was. I want to send you a new soundboard also.