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alnico51

Cnc Work Available From Jim Donahue

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A curve is made up of "true" radii, acutal parts of circles joined together. Think of a spline as a dot to dot. A spline is made up of a series of points with a curved line laid over them in a best fit kind of way. With a curve or true radius each radius can be mathmatically defined ie. it has an absolute center and radius dimension. A spline on the other hand lacks nice neat mathmatical definition. A cnc machine can cut a true radius or curve perfectly because it can be broken down into X and Y coordinates. To machine a spline that has no absolute definition in terms of X and Y, The spline must be broken into tiny staight line segments that can be defined in x and y, and make up close approximation of the spline.

When you machine a spline ( it can be done), you end up with 2 problems. The first is surface finish. Because you are machining a bunch of straight lines your curves tend to look faceted instead of smooth. This can be somewhat counteracted by breaking the spline into smaller and smaller straight line segments that more closely approximate what you have drawn, but this brings us to the second problem. Every little line segment making up your spline equals one line of code in your cnc program. This can be a problem on complex splines depending on how much memory you cnc controler has.

I don't know if I explained that very well or if anyone really cares, but if you have any questions just ask and I will try to clarify. :D

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on that lp body, what neck angle are you thinking of? Also when will you go live with one? if I ship you my wood whats the min dimensions that you need to mill out the body?

For example Tommy at USA custom needed my pieces at 19x14x1.75, he then milled it from there... is that what you are thinking?

-Derek

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on that lp body, what neck angle are you thinking of? Also when will you go live with one? if I ship you my wood whats the min dimensions that you need to mill out the body?

Bigd, I assume you were talking to me? This is my first guitar, so I would like to get a little experience milling wood before I try someone elses. I'm hoping to mill a prototype out of mdf sometime between now and x-mas. My only real concern is the carved top, the outside profile and the pockets should be no problem.

As far as the neck angle goes I am working with a 4 deg neck angle. The angle will be milled into the pocket in the body and the neck will be built straight.

The blank size you listed looks dead on, although I was thinking a LP was thicker than 1.75. Are you looking for a carved top or a flat top?

I'd love to get into milling guitar parts for other people, but I just need a little more experience before I try milling someone elses 5a top B) I'll post here when I'm ready to take on other jobs.

:D

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My only real concern is the carved top

hi

do you mind me asking how you modelled the top? From the pic above its not really possible to say how accurate the carving to the original is, since we can only see the two side shadows, you know - I am not saying that it isn't :D

I was wandering if you modelled or scanned the top and if modeled which Programm you were using ?

thanks and regards

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do you mind me asking how you modelled the top? From the pic above its not really possible to say how accurate the carving to the original is, since we can only see the two side shadows, you know - I am not saying that it isn't

I don't mind at all B)

I modelled that top using a program called Mastercam. Mastercam is a full blown CAD/CAM software, meaning I can design and generate toolpaths for my cnc all in the same software.

I can tell you right out that my model is not an exact replica of a real les paul. The 2D perimeter is right on the money, but the carve is my own creation. I have been working on this thing on and off for about a year, I'd get really frustrated trying to get it right and then I'd say screw it. Then I found Setchs build in the in progress section. The way he carved his top kind of got me headed in the right direction creating my cad model. The carve around the lower bout is probably pretty close to the real thing, but through the waist area my model is quite a bit more extreme. It's more curvey and the carve comes into the middle more than a real LP.

As far as the process I used to model the top, here goes: First I found cad file of the perimeter( John Cattos .dxf file in the download section on the MIMF). I did some clean up to that file to make the curves true radii, kind of like what I talked about above. Next I established my top thickness and my carve depth (.750 top thickness w/ .500 carve depth). From there I created a series of surfaces to create the carve. I started with the suface that lays under the finger board extension, this needed to be at a 4 deg angle, for the neck angle. Next I created the angled surface that Setch called the Pickup plane, this extends from the bridge to the end of the finger board. From there I created a series of curves that would split the top into about 6 different sections. These curves lie in 3D space, and blend from the top of the carve at a z depth of 0.000 down to the bottom of the carve at z-.500. These curves are the bounderies I used to define my surfaces.

I found it almost impossible to perfectly duplicate the real LP. Trying to copy it without expensive digitizing equipment was just too much for me. I am really happy with what I have come up with though, seems a little sexier to me, but I am a little biased :D . I can't wait to cut it!

If you want I can get some more screen shots of my model at different angles. Just let me know.

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I don't mind at all B)

hi jer7440

let me first excuse myself for not answering earlier after your perfect response - I simply did not get any reply notice on this thread until suddenly today ?!

thank you for all the detailed execution

I understood what you said about curves vs splines but I am not happy about it

That is simly so, because I love to work with the point-spline method. Actually since I do not have the right CAD yet, I use Freehand, which is just perfect for drawing shapes over an import pic. Freehand exports to *.ai vektors ....

I have designed the body and routing cavitys of my next guitar project like that and I am very happy with the result so far - the guitar is something that is nowhere else available.

Up until now I was happy to finally have all my shapes in "vektor" - the guy who I want to CNC mill it for me told me some time ago, that he simply needs my drawings vektor and that he uses Coral Draw - ( btw: I am aware of the difference between a Freehand, Coral Draw and a Mastercam)

Since the 3D drawings aren't done, it might be ok - my body is a Strat type and the body shapings will be done by hand ....

I came once across three drawings in the Les Paul Forum, which are nothing more than the shape lines (*.bmp) of a Les Paul top. However, I imagine that they would have been helpful to you in the beginning. I still have those somewhere on the computer, but since I don't have the copyright I can not puplish them. If you would like to see them, you are welcome to send me a mail.

Would I like to see more pics of your LP top. Certainly, thanks for offering. Actually,

without bad intention or hijacking - I was wondering if you would likle to take a sneak at my homepage (click on signature below) and check out if you would like

to be my first new registrant to the board and post your thoughts, pics and experiance over there. I have already opened a thread linking to this one

You know - every beginning is difficult - I created this site to make a platform to everybody interessted available- just a place to talk about it. The intelligence has to come from the participants and not from a silly administration button or whatever.

I am not the crack in the subjects that people might expect in order to follow - well I didn't want followers - I want to learn and participate just in my legue, thats all

Don't worry if you don't want to post over there - if it stays without traffic I will close it as quick as I opened it - but it could be a nice platform for the CAD and designer people :D

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Gitcad,

No worries on response time. I',m always missing stuff on here, there is just so much traffic. :D

Someone else on here, ACspike I believe is his name on the forum, has a web site with probably 20 to 30 vector outlines of various guitars. He also created a program to convert those vector outlines to DXF. When I import these dxf files all the curves import as splines.

I played with a machining simulation using one of these outlines and I found that if I turn my tolerance setting low enough I can machine these splines with almost no faceting. The programs get quite large, but for simple 2d machining it would be no problem. The faceting that does result is very fine and would be easy to sand out.

Using these spines in a 3d application would still be a pain in the butt.

On another note, I did manage to machine my les paul body over the holidays and I am very happy with the results. The 2d work and the 3d carve all came out beautifully. all I have to do is some sanding to get ready to finish. I don't have a digital camera, and I havn't taken the time to borrow one, but when I do I will post the pics right away. I have a thread started in the in progress and finished section, I'll post the pics there.

It seems we have hijacked the crap out of this thread so maybe our future dicussion would be better placed in that thread. Here it is:

3d lp thread

I will also check out your new forum.

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Hi Jim ..i might be very interested in your services..

can you email me a list of what guitar bodies and necks you have programmed already and i any example pics ( if available??)

anyone else who has receive any of jim's bodies or neck..if you have any pics available also..it would be much appreciated

Thanks MOJO

Mjochomp@aol.com

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Hey Mojo.

Jim is at the NAMM show until next week. He should be back in his shop on 1.24 or 1.25.

You'll get a quicker response if you email him your questions directly. He checks here occasionally, but gets his email a few times a day. Way quicker.

He's got pics of prior work that he can send you, but I'm sure some members here wouldn't mind sending over a few shots as well.

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Hey Mojo. 

Jim is at the NAMM show until next week.  He should be back in his shop on 1.24 or 1.25.

You'll get a quicker response if you email him your questions directly.  He checks here occasionally, but gets his email a few times a day.  Way quicker.

He's got pics of prior work that he can send you, but I'm sure some members here wouldn't mind sending over a few shots as well.

thanks Kev, i'll give that a try when he gets back from NAMM

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Still haven't seen pics of completed work, though.

I've seen a few of the 'stock' bodies (pics on Ebay), and a couple of the 'custom' ones he's done.

Your best bet is to email Jim and ask him for some pics.

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does Jim have a website?

and anyone know his email address

(i'd like to see if he could sent me some pics of some the bodies he's done

thanks :D

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Still haven't seen pics of completed work, though.

The neck I'm making is for a JEM body I bought from him. You'll see a complete work :D

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i've tried to contact Jim a couple of times for some pics of some of the bodies he's done but i've never got a response?

Jim ( or anyone else that might have some pics) if you can send me a few pics i'd appreciate it

my email is mjochomp@verizon.net

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JIM,

I sent you an e-mail, but I thought I would post the question here so that anyone else who is interested could see the answer.

Can you use a 2-D .DWF contour map to rough cut a carved/arched top? I assume you can program the tool to cut following along a contour line and then step up to the next contour. Obviously the final smothing and shaping would have to be done later by hand.

Can you (are you willing to) do it?

Thanks.

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Hey everyone, Its been a while since I left my last position, Since then I have opened my own manufacturing plant, consulting company and lumbermill. I am very busy but I do have some free time on my machine and if anyone needs some affordable CNC bodies or necks roughed out. I would like to offer this service exclusive to Project Guitar members.

I have many body shapes and a few neck shapes already programmed so if you are looking for something that you can finish I would be happy to help out.

This service is for members only and prices will be affordable. I also purchase my wood in bulk so the basic cost of the materials are usually less than other companies charge.

Cost will be quoted by job and material cost, turn around on bodies with material in stock will be in the one week range.

I can't make one of a kind custom shapes unless the drawing is supplied to scale in DXF format.

Thanks I hope this helps some of you out.

Jim Donahue

Noahjames Guitars

alnico51@comcast.net

Hi Jim.

I have been looking and waiting for someone who can produce CNC necks. I'm interested in two or three Ibanez replacement necks. Most Ibanez necks are horribly thin and I would like a direct replacement with a thicker profile. I'm looking for a even C shape with approximately a .835 thickness at first fret. Let me know if you have time to do that.Thank you.

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