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Well the new machine Cobra 404 with ATC & 5hp HTC spindle is set up, spoil board surfaced, vacuum pump working.
I have cut a couple of simple signs to practice. I have a Rhino 5.0 drawing of an acoustic neck that a friend sent me.
I need some help creating the tool paths and what bits to use. When I select surfaces for tool path it puts a box around the whole neck but I'm thinking it should be broken down into sections. Maybe heel, headstock and shaft? Any help would be greatly appreciated. I'm new so go easy on the tech terms.

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The Zootman
1109 Military Rd.
Kenmore, NY 14217
(716) 874-1498

No one using Rhino/MadCam?

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Beautiful and unusual tone woods at a reasonable price.
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The Zootman
1109 Military Rd.
Kenmore, NY 14217
(716) 874-1498

Bob
I am looking into using them so I am not experienced but if you will hang in until termite gets back from his trip you will get his expert assistance I am certain.

There is a procedure to follow when using th three d models. You can't just take the model and create the tool paths in madcam.

Sorry may e someone will chime in.


Sent from my iPhone using Tapatalk
Ken

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Ken

Toolpathing isn't really 'plug and chug' anymore than the CAD part is, so the answer to this question is quite long. I suspect that if you got the answer out of five different people here who machine necks, they'd all be different, too. A guitar neck is by far the hardest guitar part to machine quickly and efficiently, both in terms of fixturing and cutting strategy.

My standard tool for necks was a 6" long 1" 2-flute carbide ball with 4" of flutes on it. I'd rough and do profiles with a long 1/2" flat reduced neck with 1" of flutes. You can cut them 'front back' in two setups, but the most efficient way I was doing it worked all four sides- I'd prep the 'front' of all the blanks at once, and then I had a fixture with three necks on it at all times for the other three sides.

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

Well I have a 8" Z limit so I just might squeeze in a 4" long bit . Bob did you rough cut the blank on the band saw first?

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Beautiful and unusual tone woods at a reasonable price.
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The Zootman
1109 Military Rd.
Kenmore, NY 14217
(716) 874-1498

Bob,

I use Rhino and MadCam. In the past, I've broken necks down into sections, but I don't any more. What I do to create tool paths is first build a stock model solid that will contain the neck model. I actually use the profile of this stock model and a pen mounted in the spindle to create my template for bandsawing my neck blanks so that the blanks exactly match up with the stock model. MadCam doesn't force you to use rectangular stock.

When you start to build the toolpaths in MadCam, when you get to the point where it is prompting you for the size of the stock, whether to add extra space to accomodate the diameter of the tool, etc., select the stock model solid instead of using the rectangular dimensions that MadCam will default to. You can hide the stock model after this step. At that point, you can go ahead and select your roughing toolpath options and move along.

Hope that helps at least some--I have 8" of Z travel and use a 4" long 1/2" two flute ball end mill for everything. I hold the neck blank down to a spoilboard with screws (I used to use vacuum for this, but had problems on occasion when roughing out the peghead). The screws go along the centerline that is routed later on to accomodate a truss rod. I machine everything from the back. I could probably get a closer to finished cut if I rotated the neck like Bob suggests, but I get a pretty darned good cut just doing it the way I do, and it simplifies the jigs/indexing a lot.

Dave

Dave that is a big help although I'm not sure I understand all of it. I will try to work my way thru it. I do have a Rhino drawing to work with. So if your routing from the back how do you attach the screws? Do you leave stock for a finish cut?

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Beautiful and unusual tone woods at a reasonable price.
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The Zootman
1109 Military Rd.
Kenmore, NY 14217
(716) 874-1498

Hi Bob,
Like Ken said, I am headed out on a trip to help a friend out. I will be driving a uhaul truck from Wisconsin to Mississippi.

If you want, send me the model and let me take a look at it, and I may or may not be able to help much before I leave in the morning. Pm me your email address and I will email you directly.

Mike

ps Ken if you see this, call me around 7:30pm central time tonight.

Mike can you PM me your email address?

_________________
Beautiful and unusual tone woods at a reasonable price.
http://www.rctonewoods.com/RCT_Store
The Zootman
1109 Military Rd.
Kenmore, NY 14217
(716) 874-1498

I run the screws into the fingerboard surface (that will later be routed out for a truss rod anyway). I do the usual roughing/planar/z-level finish cuts along with pencil tracing. When roughing, I do leave stock for the finish cuts--maybe .050 or so.

I don't get too worried about the finish on the final cut since I want to do some handwork to finish it all up--at a point the extra time on the CNC doesn't seem to be worth it since the handwork is pretty minimal. But I still have very little sanding to do after cutting a neck. I can cut a banjo neck (including cutting the peghead shape and some details that are hard to do by hand) from start to finish in about 40 minutes or so. I tend to run my machine at 150 to 200 ipm for cutting and take pretty conservative cuts as far as depth is concerned since I'm usually working figured maple that would just love to chip out. I could cut necks in about half that time if I were only working mahogany or some other less-prone-to-tearout wood. On a guitar neck, it would probably be a bit faster, since the asymmetrical nature of a five string banjo neck adds some complexity to the model.

I'll have to look at the file size, but I could probably email you a Rhino model to show what I'm talking about regarding the stock model. I think the ease of using user-defined stock models is one of MadCam's strengths, but it's not straight forward until you've actually done it.....


Dave

Dave if the finger board side is face down on your spoil board how do you drive screws into the truss rod area. Are you mointing the neck to a piece of mdf . Creating the stock model is what I need to learn. Sending me a file would be great. I can also send you my file to look at.

_________________
Beautiful and unusual tone woods at a reasonable price.
http://www.rctonewoods.com/RCT_Store
The Zootman
1109 Military Rd.
Kenmore, NY 14217
(716) 874-1498

Bob,

I can send you a picture of what my fixture looks like. Mine is Baltic Birch instead of MDF, but it's a two-part affair with some index pins. It will be tomorrow evening before I can see what my Rhino files look like, but I'd be happy to send them if they're email-friendly. Elsewise, I can do some screen caps or whatever to get the idea across. PM me with your email address and I'll get back in touch offline.

Dave

Can you post some screen shots or photos here please.
Termite, I did not see this until later. I can wait until you finish your good deed.

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Ken

Here are some pictures of my arrangement. I have a main spoilboard with index holes that clamp down to my T-Slot table. A "sub jig" with matching index pins clamp on to the spoilboard. In turn, a neck blank with matching index holes is screwed onto the "sub jig" before clamping to the spoilboard.

Maybe overly complicated, but in my situation it works. Hope this helps.

Dave

The holes down the center of the neck are screw holes for holding in place. They'll rout away when I put the truss rod in place (I use the same index holes in my jig for cutting the truss rod slot). The thick "sub jig" gives room for the ball-nose bit to protrude below the surface of the model to accurately cut the profile of the neck without cutting into the table top. Not having to change cutters is nice when you don't have one of them there fancy CNC auto-change-thingies....

Dave

Thank you.

Question: how do you shape the fingerboard side and peghead angle? is that set before you put it on the jig?

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Ken

Yep, I cut the peghead angle with the bandsaw or sometimes a table saw, true it up on a Uniplane with a jig that cuts everything like I want it and run the fingerboard surface over a jointer. Then I use a jig to position the index holes based on the transition of the fingerboard surface to the peghead surface as a guideline, so the downward faces are established before I ever hit the CNC . I also bandsaw the blank to its profile at this point since both the fingerboard surface and the peghead surface are "etched in stone" at this point, and these surfaces are what's critical to the stock model. The bandsaw pattern is printed straight off of my stock model design from MadCam, so the final neck blank and what I have modeled in Rhino/MadCam are pretty much identical (as long as my bandsaw skills hold out....)

Dave

Thanks Dave. The picture are a great help. So the stock model is an oversize model of the finished drawing that you import into your actual model before running the tool path?

_________________
Beautiful and unusual tone woods at a reasonable price.
http://www.rctonewoods.com/RCT_Store
The Zootman
1109 Military Rd.
Kenmore, NY 14217
(716) 874-1498

Ken what version of Madcam 5 do you have? Only the 4 axis and up have the stock model option. You can achieve the same thing by using region curves and clipping planes, but it does require a little more computer time, though once you use it a few times, it will become second nature to you.

If you don't have the 4 axis version, post here and I will check in later. Hoping I can borrow that laptop!!! I hate having to try to do cad work on them, but at times I know I need to get one!

Mike

Yes pretty much. It actually looks just like the band sawed blank. I do have the 4 axis MadCam--I didn't know that stock models weren't available in 3 axis. What I did for necks prior to working out stock models was to split the neck into 3 pieces--heel, shaft and peghead. I then created an appropriate box for each and ran the toolpaths separately. It cut out a lot of "air cutting" time, and worked quite well.

Dave

I have not purchased Madcam yet. Do I need to get the 4 axis even though my machine is only 3 axis? This software stuff is starting to seem like smartphone commercials. He He

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Ken

I used the three axis version for a long time before I added my 4th axis and never had any problems. The stock model feature is nice though--I had thought that came along with version 5, but I upgraded to 4 axis at the same time and apparently that's where I got that functionality. But the 3 axis version worked fine for me for doing necks, archtop plates, etc.

Dave

did you route the neck yet Bob? Any progress.

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Ken

Waiting to hear from termite. I sent him my Rhino file

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Beautiful and unusual tone woods at a reasonable price.
http://www.rctonewoods.com/RCT_Store
The Zootman
1109 Military Rd.
Kenmore, NY 14217
(716) 874-1498

I do top / bottom machining. I used to do top and L/R sides but the accuracy and positioning of the fixtures is critical or the seam shows or there is asymmetry in the part. This was using a carrier arrangement like Dave's but different and a pedestal that the carrier bolted to. I still have that somewhere or could find some old pictures if somebody wants. I'm doing electric parts so I didn't have to deal with the dovetail. With top/bottom the key is drilling the index dowel holes on the top side ops that get used to locate the part for the bottom side. I'm using a vacuum fixture but it could easily be holes in the spoilboard with double sided tape for low volume.