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Need Advice on Circle Cutting and Rossete
http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=51339		 Page 1 of 2
Author:  6string [ Sat Dec 15, 2018 8:39 am ]
Post subject:  Need Advice on Circle Cutting and Rossete
This is my first rodeo. I finally ordered the material for the soundboard, neck blank, and bracing after about a year and a half of talking myself into and out of building a guitar several times. So anyway, now Im fully onboard with seeing this through to the end, whatever the outcome. So Im probably going to ask some really dumb questions that are totally obvious to most of you. I am an accomplished woodworker, and have built many really nice pcs of furniture, but this is a totally different ballgame.

My question is about cutting the soundhole and rosette channel. What tooling is best? I see Stewmac has the dremel circle cutting jig, but then I need the base as well (already have a dreme)l. Which would be around $200 I guess for both. This might be a little costly for me for a first guitar, but probably I will build more later most likely. Also the upgraded base kit I was looking at comes with a binding channel guide, but how well does that work. I see a lot of people use some different jigs for binding and purfling so maybe this isn't a good choice. Just trying to be wise with the dollars spent. Is there any other less expensive way of doing this, that would yield just as good of results. Talking about soundhole, rosette with purfling, and binding with purfling. The book I have been studying used a regular hand held router and a handmade circle jig. I already have 3 routers.
Author:  Greg Maxwell [ Sat Dec 15, 2018 9:17 am ]
Post subject:  Re: Need Advice on Circle Cutting and Rossete
You can cut rosette channels and sound holes using a fly cutter in a drill press. Buy a couple extra cutter blanks and carefully grind your own cutters. I use two, one is .040 and the other is .100. If you make them correctly they will cut nice clean channels. I use a table with a 1/4" brass insert as the base, and start the cutter with the center pin in the insert with the work clamped down. This setup will cost less than a circle cutter jig and dremel.
Author:  Clay S. [ Sat Dec 15, 2018 11:41 am ]
Post subject:  Re: Need Advice on Circle Cutting and Rossete
If you already have 3 routers you could make a simple circle cutting jig by making a new sub base for one of them. Here is a commercial version, but a simpler home made version can be made with just the "holes" needed for the rosette:

www.youtube.com/watch?v=GQMdETyWGRo
Author:  Woodie G [ Sat Dec 15, 2018 11:56 am ]
Post subject:  Re: Need Advice on Circle Cutting and Rossete
The Wells-Karol router base works well...adjustable to a few thousandth and very accurate...here are links to Mr. Chris Paulick's video on construction and Mr. Wells' site to purchase one already made up.

https://youtu.be/9oRqUK-CMIo

http://www.wellsguitars.com/Available_Instruments/Luthier_Tools.html
Author:  Pat Foster [ Sat Dec 15, 2018 12:12 pm ]
Post subject:  Re: Need Advice on Circle Cutting and Rossete
Here's the style commonly used by classical builders. I made one in about two hours. The only cost was for the iron, which was a replacement for the Ibex purfling cutter, reground to put a double-bevel on the business end. It's slower than a power tool, but I get perfectly clean cuts. After the cuts are made, use a small router plane, or careful work with a chisel to cut out waste.

Attachment:
Screen Shot 2018-09-03 at 9.46.31 PM.jpg


Or, make one like this, though buying one might be a more efficient use of your time.

Attachment:
DSCN8233.jpg


Having both, I make the initial cuts with the classical type, then use the lam trimmer for cleanout to within a 32nd or so of the initial cuts, and finish up with a chisel.

Pat
Author:  Clay S. [ Sat Dec 15, 2018 12:47 pm ]
Post subject:  Re: Need Advice on Circle Cutting and Rossete
One other thing - don't glue the bracing on your soundboard until you have the rib set completed and are near the point of closing up the box.
Author:  meddlingfool [ Sat Dec 15, 2018 12:54 pm ]
Post subject:  Re: Need Advice on Circle Cutting and Rossete
I would not recommend the dremel for routing binding channels...
Author:  6string [ Sat Dec 15, 2018 1:03 pm ]
Post subject:  Re: Need Advice on Circle Cutting and Rossete
Clay S. wrote:
One other thing - don't glue the bracing on your soundboard until you have the rib set completed and are near the point of closing up the box.


Glad you mentioned this. I was actually planning on working the top bracing after the rosette and I haven’t even purchased the back and sides yet. Didn’t know it was an issue. What is the reason for this anyway, and I guess it would be another thread for me to ask what is the recommended sequence of work. The book I have by William Cumpiano I don’t think really mentions it.
Author:  6string [ Sat Dec 15, 2018 1:06 pm ]
Post subject:  Re: Need Advice on Circle Cutting and Rossete
meddlingfool wrote:
I would not recommend the dremel for routing binding channels...


Laminate trimmer then? Or I was also thinking of making a fixture for my router table but didn’t know if I’m just asking for issues.
Author:  George L [ Sat Dec 15, 2018 2:59 pm ]
Post subject:  Re: Need Advice on Circle Cutting and Rossete
I cut my rosettes the way Pat Foster describes above.
Author:  meddlingfool [ Sat Dec 15, 2018 3:08 pm ]
Post subject:  Re: Need Advice on Circle Cutting and Rossete
Clay S. wrote:
One other thing - don't glue the bracing on your soundboard until you have the rib set completed and are near the point of closing up the box.


Why do you say this? As long as the RH is constant, it should be fine. I've got a top in my rack I braced in 2011, its ready to use at any time.

But I guess that brings us to a very important issue, climate control. 6string, do you have a way to accurately monitor and control relative humidity?

And yes, a laminate trimmer for the bindings is good, but I have seen fixtures for the router table too...
Author:  Clay S. [ Sat Dec 15, 2018 3:54 pm ]
Post subject:  Re: Need Advice on Circle Cutting and Rossete
Yes, climate control. It is common for many amateurs (myself included) to not have total control over the relative humidity during all stages of building. Many builders have had tops "potato chip" when the time between bracing and gluing to the rims is extended because of relative humidity changes, and even when the relative humidity goes back to what the top was braced at, the top doesn't always return to it's original shape.


" I've got a top in my rack I braced in 2011, its ready to use at any time."

I wish I had that good of R.H. control. That is impressive! Bravo! [clap]
Author:  meddlingfool [ Sat Dec 15, 2018 4:57 pm ]
Post subject:  Re: Need Advice on Circle Cutting and Rossete
Yeah, once wood shrinks, it rarely regains its original dimensions. Another good reason for cooking tops.

I am fortunate to live in Pacific Northwest which is fairly benign in humidity fluctuations. My main building room is about 10x12, easily kept at 40% with an old Kenmore dehumidifier and a cheap London Drugs humidifier. My tool room and sidebending area are monitored but not controlled.

Any way, I guess the point for 6string is that there is no reason not to brace your top at any point during the process, as long as the wood is kept at a fairly stable RH. There's nothing inherently wrong with bracing it before making the body.
Author:  6string [ Sat Dec 15, 2018 5:10 pm ]
Post subject:  Re: Need Advice on Circle Cutting and Rossete
I’m also in Pacific NW, so I don’t really forsee any issues with humidity here. I guess I will go ahead with my original plan of working the top first. Really my only motivation for this is I am buying the material step by step as I can afford it. So I was thinking basically it is going to take me a couple of months to aquire everything. Figured I would work on something while waiting to buy additional materials. I don’t know if this is a common or preferred method, but that’s the card I’m dealt at the moment.
Author:  Pmaj7 [ Sat Dec 15, 2018 5:48 pm ]
Post subject:  Re: Need Advice on Circle Cutting and Rossete
6-string, what part of these Woods are you in?

You don't foresee any humidity problems, because you are monitoring and controlling or just don't think it will swing that much? It's mild here, but it can definitely swing enough to turn your top into a potato chip. Unless you're keeping your work area climate controlled 24/7, I would do the rim first and make sure to brace in 40-45%. Including side braces, or don't use them.

New username, same ole Pat Mac
Author:  meddlingfool [ Sat Dec 15, 2018 9:08 pm ]
Post subject:  Re: Need Advice on Circle Cutting and Rossete
RH is very important, monitoring it is cheap, you just need a hygrometer. Moderating it is more costly.

I'd be with Clay then that unless you are sure your RH is correct, that bracing your top and getting the box closed should be done in as short a time as possible.

But do yourself a favour and get a hygrometer so you know what's going on, which will dictate what you can or cannot do...
Author:  6string [ Sat Dec 15, 2018 10:19 pm ]
Post subject:  Re: Need Advice on Circle Cutting and Rossete
Pmaj7 wrote:
6-string, what part of these Woods are you in?

You don't foresee any humidity problems, because you are monitoring and controlling or just don't think it will swing that much? It's mild here, but it can definitely swing enough to turn your top into a potato chip. Unless you're keeping your work area climate controlled 24/7, I would do the rim first and make sure to brace in 40-45%. Including side braces, or don't use them.

New username, same ole Pat Mac


I’m on the Kitsap Penninsula.

Nope not monitoring or controlling humidity. Probably need to think about doing that.
Author:  Clay S. [ Sat Dec 15, 2018 10:21 pm ]
Post subject:  Re: Need Advice on Circle Cutting and Rossete
Indoor humidity fluctuates a great deal according to the outside temperature around here (and most places). In the winter the outside relative humidity might be 60 % but the indoor relative humidity will be in the teens. Relative Humidity is the percent of moisture the air is holding compared to how much moisture it can hold. Cold air can't hold as much moisture as warm air, so when you heat the air in your house the R.H. drops considerably. Unless you live where the temperature always remains the same (or you humidify/dehumidify the air) you will have indoor humidity fluctuations.
As Pat mentioned, glue and assemble things at 40-45% relative humidity (including when you glue the top and back to the sides, fingerboard to neck, etc.). Not everything needs to be done at 40-45% R.H. - neck carving, side bending, sanding, and to some extent finishing can be done in ambient conditions.
Author:  Terence Kennedy [ Sat Dec 15, 2018 11:51 pm ]
Post subject:  Re: Need Advice on Circle Cutting and Rossete
This laminate trimmer jig was described in the Charles Fox course when I took it in 2004. It served me well for a number of years and is simple to build. I finally coughed up the dough for the Bishop Cochran base and that is the real goods. http://www.bishopcochran.com/

Image

Image

I think a good laminate trimmer has big advantages over a Dremel in my experience.
Author:  klooker [ Sun Dec 16, 2018 9:19 am ]
Post subject:  Re: Need Advice on Circle Cutting and Rossete
I use a Jasper router compass and various size end mills.

There is a lot of head scratching figuring out the ID and OD of the various size bits related to the pin postitions is the compass but I made a spreadsheet that lists them all so I can look up the target diameters I need, pick the appropriate bit and set the jig accordingly.

Kevin Looker

edit:
Here's what I want but I don't think I can afford one
viewtopic.php?f=10101&t=47382&hilit=router
Author:  Colin North [ Sun Dec 16, 2018 9:24 am ]
Post subject:  Re: Need Advice on Circle Cutting and Rossete
I bought a Wells-Karol router base from a member who made several some time ago and it is a vast improvement on the Dremel. Use it with a Makita 700 lam trimmer
Author:  Robbie_McD [ Sun Dec 16, 2018 9:44 am ]
Post subject:  Re: Need Advice on Circle Cutting and Rossete
I also use a Wells-Karol base that I built from UHMW after watching the Chris Paulick video.
Amazingly accurate and clean cuts using a Ridgid laminate trimmer...
Author:  6string [ Sun Dec 16, 2018 12:33 pm ]
Post subject:  Re: Need Advice on Circle Cutting and Rossete
Lowes has the Bosch Colt Trimmer on sale right now for $89.
I bought one last night, probably make something similar to this.
http://blackwaterriverguitars.com/Tools ... utter.html
Author:  6string [ Sun Dec 16, 2018 4:54 pm ]
Post subject:  Re: Need Advice on Circle Cutting and Rossete
[quote="Robbie_McD"]I also use a Wells-Karol base that I built from UHMW after watching the Chris Paulick video.
Amazingly accurate and clean cuts using a Ridgid

Took another look at the video and I like the ability to make finite adjustments to the diameter.

Ordered a pc of 3/4 UHMW from amazon, probably gonna build this jig next week.
Author:  Rod True [ Sun Dec 16, 2018 7:14 pm ]
Post subject:  Re: Need Advice on Circle Cutting and Rossete
6string wrote:
Pmaj7 wrote:
6-string, what part of these Woods are you in?

You don't foresee any humidity problems, because you are monitoring and controlling or just don't think it will swing that much? It's mild here, but it can definitely swing enough to turn your top into a potato chip. Unless you're keeping your work area climate controlled 24/7, I would do the rim first and make sure to brace in 40-45%. Including side braces, or don't use them.

New username, same ole Pat Mac


I’m on the Kitsap Penninsula.

Nope not monitoring or controlling humidity. Probably need to think about doing that.


I’m on the Wet coast too and if you don’t monitor you WILL see humidity issues, 100% guaranteed. Ask me how I know...


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