Compound Radius methods. What's yours?

[Stu]

I was on another forum ( Yep, I cheated on you ) and a question was posed to me in regards to my method of compound radiussing and whether there are other methods to do this.

I guess first I should spill the way I achieve these and hopefullly you guys may have other ways to achieve the same result. Not necessarily looking for a better way, but curious how many alternatives there are out there.

This isn't really a tutorial as I don't have a great resource of pics for each step, nevertheless I'll post a few .

This one is 7.25" at the nut and 12" at the rosewood f/board end.


I'll rough in each end first using the trusty no.5 plane.
I'll then plane then centre sections from end to end whilst checking with a straight edge parrallel to each string's path along the board.
Once that's roughed in, I'll continue along the string's path using a straight edge with sandpaper ( Double sided tape here).
I'll go through the grades from 240 to 2000 grit and finish using radius blocks. (overkill , I know )

[Allen]

I built a pendulum that I stuck the fret board to that had a pivot at each end with a different radius. I swung the board over my router mounted in a table. Worked good on some woods, but some I had catastrophic wood explosions and shrapnel flying everywhere, so I gave that method up.

I think that a mechanical method like that would be better suited to an abrasive set up, like using a large belt sander.

Lately I haven't bothered with compound radius boards. I use the long alloy beam from Stew Mac, and just make it a 16" radius. I've got to convince the treasurer that I require some other radius beams though.

Your fret board looks incredible btw.

[Stu]

Thanks for that Allen.

I saw last night on youtube a set up that would do what you mentioned.
It is a pendulum and long bed belt sander combo.
It would take a bit of calibrating to get right and I'd imagine would only
be useful if setting up for a larger batch run, not individual custom jobs.

I'm more interested in the methods without the larger machinery.

[youtube]http://youtube.com/watch?v=i_TrjG2gTq4[/youtube]
[
Cheers, Stu

[graham mcdonald]

A very simple approach. I just take about 1mm off each edge of the tapered board with a plane and then curve the rest of it with half a sheet of 80grit paper glued to a piece of MDF. Absolutely no idea what radii I end up with, but it seems to work quite well. It is essentially the method described in Jim Williams' book which I think many people have used for years without knowing it was called a compound radius.

cheers

graham

[Ethereal Guitars]

My method is somewhat similar to Graham's.....

I radius each end with 80 grit on the desired radius block. Once I have achieved say 9.5" at one end and 12" at the other I simply "join the two' ends with a long aluminium radius beam.

This is very manual, takes a reasonable amount of time and is of course open to error. I check progress regularly with radius guages and a machined straight edge however and have been pleased with the results.

I guess, like Oz alluded to, it doesn't matter so much how you get there, as long as the result is desirable. Interesting thread though and prompted me to join this forum........looks like an informative pleace to be!
Cheers folks,
Jon

[Allen]

Welcome on board Jon. Glad that you've joined into the discussion.

Cheers

[Dave]

Hi sorry to jump in on this thread but would anyone have any drawings of radius templates for fingerboards as I'm just making a fret press and would like to make some cowels! Also it will help me see what different radius look like, and decide which feels the most comfortable.

If any one can help I would be very grateful

many thanks
Dave

[Lillian]

Here you go Dave.

http://www.pickguardian.com/pickguardia ... Gauges.pdf

[Dave]

Many thanks Lillian you're a star! just what I was looking for

Dave

[Lillian]

I did the easy part Dave. You get to do the hard part, cutting them out accurately.

If you are looking just to hold something to get a feel for it, you can make quick mock ups. Cut a board the size of your anticipated fretboard. Put rails on the sides, not very high 5 mm should do it. Cut the radius into thin ply or something else a bit sturdy. Fill the board with auto body filler, we call it Bondo, until you have enough to run the radius gauge of choice down the fretboard, scraping off the excess. Allow to harden and repeat as necessary to fill in from any shrinkage.

[Dave]

Many thanks for the advice Lillian

I did the easy part Dave. You get to do the hard part, cutting them out accurately.

Yes I feel the onset of failure already lol

Dave[/quote]

[Lillian]

Dave, go to the kitchen and start looking around at your pots, jars and bottles. I'm sure you will find something that you can put a piece of sandpaper around to help smooth out the gauges. Remember close is good enough, it doesn't have to be perfect. No one will be able to feel the difference between a 7" and a 6 7/8" radius.

[DarwinStrings]

Hi sorry to jump in on this thread but would anyone have any drawings of radius templates for fingerboards as I'm just making a fret press and would like to make some cowels! Also it will help me see what different radius look like, and decide which feels the most comfortable.

If any one can help I would be very grateful

many thanks
Dave

Hi Dave. I am not sure I like the idea of printing out stuff and using it as your radii, If you just use a compass direct onto Perspex/Lexan (depending on where you are), steel, brass, wood or just about anything it will be accurate. You can use a scriber or blade instead of lead in the compass and may find it easier to cut with accuracy.

Alternatively use a Edge Trimmer or Router as a compass, and rout out your templates.

As for trying out different radii on a fret board, go into a guitar retailer and ask which guitars have what radii then sit down and have a bash.

Good luck however you choose to do it.

Jim

[Dave]

Hi thanks for you're replies

Hi Dave. I am not sure I like the idea of printing out stuff and using it as your radii, If you just use a compass direct onto Perspex/Lexan (depending on where you are), steel, brass, wood or just about anything it will be accurate. You can use a scriber or blade instead of lead in the compass and may find it easier to cut with accuracy.

Alternatively use a Edge Trimmer or Router as a compass, and rout out your templates.

As for trying out different radii on a fret board, go into a guitar retailer and ask which guitars have what radii then sit down and have a bash.

Good luck however you choose to do it.

Jim

Thanks for the advice Jim - the only problem where I live is that the guitar shops don't tend to carry the high end makers like Martin, Taylor, Lowden etc... They tend to stock lower end guitars, which are fine but I would like to get a balanced view from a £50 special to £.....s the skies the limit:(

If I was to be really acurate how would you set out a 7ft radius or a 20ft radius as I'm having a go at some radius dishes for backs after the fret press? I've built really large tables in the past and have set out on sheets of ply to full scale as I had to machine the timber! I'm not sure how to do this with out going to the extremes of using large sheets of ply and a lot of manual graft - which I try to stay clear of at all cost lol!

Dave, go to the kitchen and start looking around at your pots, jars and bottles. I'm sure you will find something that you can put a piece of sandpaper around to help smooth out the gauges. Remember close is good enough, it doesn't have to be perfect. No one will be able to feel the difference between a 7" and a 6 7/8" radius.

That makes sense Lillian thanks p.s. I'll nick the wifes marmalade jar I'm sure she won't mind a bit of dust lol

Many thanks
Dave

[Lillian]

Dave, fret boards are in inches, tops and backs are in feet. You can make a beam compass to accurately draw the radius.

[Dave]

Dave, fret boards are in inches, tops and backs are in feet. You can make a beam compass to accurately draw the radius.

I'm sorry Lillian got a bit confused it's been a hard day lol!

But I would still like to know how to set out for the Radius dishes if anyone could give me any pointers?

Sorry again for hijacking Stu's post!

Cheers
Dave

[DarwinStrings]

Check the Tutorials Dave.

http://www.mcguitars.com.au/forum/viewtopic.php?t=231

Jim

[Dave]

Check the Tutorials Dave.

http://www.mcguitars.com.au/forum/viewtopic.php?t=231

Jim

Thanks for the link Jim but I still need to find out how I work out the radius without going full size.

Best wishes
Dave

[graham mcdonald]

The MIMF site has downloadable PDFs of the common back and soundboard radii. The tutorial Jim mentioned is the simplest and easiest way I have found to make radius dishes. $20 worth of bits from Bunnies and a couple of hours work. Again, it doesn't really matter if the radius of a dish isn't exactly 15' or 25' or whatever. The important part is the insurance that an arched top and back builds in, and the visual part that a gentle curve in a soundboard or back looks better than a flat plate (which probably isn't going to stay flat anyway).

While the current fashion is for both backs and soundboards to essentially become sections of a sphere of that radius, it is worthwhile taking a look at Eugene Clark's methodology for building classicals in the Winter 2007 edition of American Lutherie (No 92). I found it so intriguing that I have built my first classical guitar in 20 years. I glued the bridge on yesterday using a rubbed animal glue joint. That was interesting

Eugene (who is just one of the most delightful people in the world) says that this approach to building is very much as the Spanish builders were doing a century ago, and though the plates are domed/arched with braces, it is a different way of thinking about it.

cheers

graham

[Kim]

Here ya go Dave,

But it won't work in firefox, use the IE browser.

http://kalantarian.org/artak/gm/depthcalc.htm

Cheers

Kim

[Dave]

The MIMF site has downloadable PDFs of the common back and soundboard radii. The tutorial Jim mentioned is the simplest and easiest way I have found to make radius dishes. $20 worth of bits from Bunnies and a couple of hours work. Again, it doesn't really matter if the radius of a dish isn't exactly 15' or 25' or whatever. The important part is the insurance that an arched top and back builds in, and the visual part that a gentle curve in a soundboard or back looks better than a flat plate (which probably isn't going to stay flat anyway).

While the current fashion is for both backs and soundboards to essentially become sections of a sphere of that radius, it is worthwhile taking a look at Eugene Clark's methodology for building classicals in the Winter 2007 edition of American Lutherie (No 92). I found it so intriguing that I have built my first classical guitar in 20 years. I glued the bridge on yesterday using a rubbed animal glue joint. That was interesting

Eugene (who is just one of the most delightful people in the world) says that this approach to building is very much as the Spanish builders were doing a century ago, and though the plates are domed/arched with braces, it is a different way of thinking about it.

cheers

graham

Many thanks for the reply Graham and the tutorial - Where would I be able to get hold of a copy of American Lutherie? I'll check out the MIMF website for the PDF's so thankyou!

Here ya go Dave,

But it won't work in firefox, use the IE browser.

http://kalantarian.org/artak/gm/depthcalc.htm

Cheers

Kim

Thanks Kim thats a fantastic help and will save me a lot of head scratching and swearing lol

I love this site as you guys really go that little bit extra and I'm glad I found you when I did

Cheers
Dave

[graham mcdonald]

American Lutherie is the quarterly journal of the Guild of American Luthiers. A membership from Australia works out to around $80-100 a year or $20-$25 a journal. I have all of them, and I don't think there is one edition that doesn't have $25 worth of good ideas. And their conventions every two years or so are an encouragement and a wealth of good ideas.

They do sell individual back issues and you can download a pdf with an index of all the contents. They also have combined the articles into now 4 or 5 Big Red Books which are a great investment in information.

cheers

graham

[Stu]

Thanks to all those that replied with their different methods.
There's always a few different ways to skin a cat and I must admit I've learnt a few simpler methods here as well.

Of course if there are any others.............................


cheers, Stu