Rrrasp!

[David Song]

Hi,

Can someone tell me the main differences between Modeller and Cabinet raps. I know one is thinner.

My application will be for carving/shaping guitar necks. If you don't know what a guitar neck is...how about shaping baseball bat.

Also, what are the length and teeth per inch differences has to do with the application?

I am looking at a Gramercy, TBT, and Auriou. Could you recommend one or two rasp for general wood working? sort of like Nicholson 49.

thanks!

[David Keller NC]

A modeler's rasp, as you noted, is a half-round shape, typically smaller and finer teeth than a cabinetmaker's rasp. The european design for a cabinetmaker's rasp (basically TBT, Auriou, Grammercy) also taper to a point like a modeler's rasp. The Nicholson pattern ends in a cut-off tip.

The nicholson #49 is a very coarse rasp designed for fast stock removal. It's about an equivalent to a G7 or G8 in Auriou's terminology. It doesn't leave fine finish, so you will need to follow up with about a G12 and then sandpaper or a spokeshave.

What TBT sells is made by former Auriou employees, and is basically the same thing except that you don't have to wait for it to get shipped from Europe.

Regarding shaping guitar necks, probably the fastest way is with a router and a round-over bit, followed by a coarsely set spokeshave. An all-neander route that's almost as fast is with about a #5 gouge, 20mm with a back-bevel so that it can be used upside down. A rasp is a slower method with a more determined outcome - you have to know what you're doing with a carving gouge to avoid splitting out the grain, but it's way faster than any rasp.

[george wilson]

Old Spanish guitar makers used a home made knife for shaping neck heels. I made a few for myself,but do not advocate the way they made theirs.

They made a wooden handle about 18" long,and ground down a straight razor blade for the knife. I made one like that,grinding down the razor blade till it was 1/2" wide,with straight,not hollow ground sides. I drew it to a purple color,and sharpened it up razor sharp. It broke almost at once with surprisingly little pressure on the wood,and the blade almost hit me in the face. This was in 1965.

I decided that a razor,which has very high carbon content,like a file,is too brittle at any temper,so I made a blade out of 1/8" spring steel strip 3/4" wide. You can get it from any gunsmith supply like Brownell's. I heated the finished blade orange,and quenched it in water,easily done with a torch. Then,I polished it some and drew it blue. It has always been satisfactory. It needs to be blue,a spring temper,so you can really bear down on it hard without it snapping off.

The blade is about 3/8" wide at the tip,and tapers to 3/4" at the handle. The handle has a brass ferrule made from pipe where the blade goes into it.

This knife is used by clamping the neck with the heel upwards on a bench. With the long handle,and standing over the neck,a lot of cutting force can be brought down against the blade to quickly rough out the heel. Push down near the ferrule.Use the other hand at the far end to twist the knife and control its cut.

[David Keller NC]

David - One other comment that I forgot about yesterday in my reply; probably the single fastest Neander way to accomplish what you're after is with a drawknife - it took walking down to my shop and seeing the shavehorse sitting in the corner to remind me of that.

Personally, I prefer a carving gouge, but that's just personal bias - a drawknife in skilled hands is a wonder - from square with sharp corners to smoothly rounded in about 2 minutes.

[David Song]

Thanks guys!

So here is the direction I'm heading.
I went ahead and bought me a Shinto rasp. It's suppose to be very agressive and moves material fast. I'm now looking for a quality rasp to go after Shinto rasp but also before fine file or sand paper. Perhaps this is where cabinet or modeller rasp from Gramercy, TBT, Auriou comes in to picture. Now I just need to know if modeller or cabinet, how many tpi, and which length I need.

[David Keller NC]

Given what you're going to be working on (guitar necks), I would choose a TBT shallow curvature, 8" long, G11 cabinet-makers rasp:

http://www.thebestthings.com/newtools/hand_cut_french_cabinet_rasps.htm

(Model 4-200-13-AU - Actually, I think this is an error in the model number - it should be 4-200-11-AU). You might even choose a G9 if most of your guitar necks are going to be maple.

[David Song]

Given what you're going to be working on (guitar necks), I would choose a TBT shallow curvature, 8" long, G11 cabinet-makers rasp:

http://www.thebestthings.com/newtools/hand_cut_french_cabinet_rasps.htm

(Model 4-200-13-AU - Actually, I think this is an error in the model number - it should be 4-200-11-AU). You might even choose a G9 if most of your guitar necks are going to be maple.

What if Most of my guitar neck will be Mahogany?

Thank you

[Chuck Nickerson]

The Shinto rasp will work flats and convex curves. For working concave surfaces, you'll nee a rasp with a convex surface. I'll also put in a good word for Gramercy rasps at TFWW.

[David Keller NC]

David - In the case of mahogany, I might choose a slightly finer rasp, as the wood's softer and tears more easily.

Generally speaking, what you're trying to do is very close to roughing out the cabriole portion of a ball & claw chair leg, which I do a lot of. As I mentioned before, I generally hog off the waste with a carving gouge, perhaps do a little shaping with a Nicholson #50, and finish up with a spokeshave. However, the Auriou rasps come into play at the underside of the cabriole curve, which is difficult to work with a shave. In that case, I'm using a medium curvature G13 rasp, and finish the surface with a cabinet scraper.

[george wilson]

Is it a sin to mention Surforms? they are not attractive tools,but they can remove mahogany without tearout,and are not very expensive to replace when they get dull.

Speaking of dull,does anyone ever sharpen their files? Rasps would sharpen up even better. I have sharpened needle files by suspending them in a beaker of diluted muriatic acid.A little battery acid helps,too. I just reverse electroplate them,that is,electro strip them.Many years ago,apparently you could take files and get them resharpened like this.

A file,or rasp,is such a consumable tool. I'd hate to pay $85.00,or more for a rasp. In metal work,a new file is supposed to be good for 40 hours,I have read in old books. Woods can be quite abrasive. It might be well to rig up a 1 1/2 volt D.C. power supply,and try sharpening old rasps.

[JD Dolan]

George, you can still get rasps and files sharpened:

http://www.boggstool.com/index.htm

[george wilson]

That's good to know,though I can do my own.

[Phillip Pattee]

This lateral rasp made by Gaignard Millon in France is designed for shaping necks. You use it much like a draw knife. I don't know much about this company or the quality, but they do offer a complete line of rasps.
http://www.gaignard-millon.com/produits.asp?categorie=Râpes%20et%20limes&souscategorie=Râpes%20piquées%20main&soussouscategorie=Latérale&num=1432

This bent micro draw knife made by Northbay Forge is also a useful tool for shaping curves. http://www.northbayforge.com/dk.htm

[george wilson]

I'll tell you what I use,and it didn't cost a fortune. I found a new horse shoeing rasp that had been broken somehow. It has big rasp teeth on 1 side,and on the other it has a very coarse file with very sharp teeth. I broke the file off,and made a 4" long short file that is about 1 3/4" wide,and short enough to plane up and down a guitar neck,and take the waves out of the previous stage of work. The coarse file has about 16 teeth per inch,and they are sharper than any cabinet file I have seen. You can get them at any feed and seed store.Don't know the current cost. If you had a whole one,you could make at least 2 of the 4" neck files.

The file is also useful for any kind of fairly straight table legs,like Queen Anne style.