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Who is your go vendors for Cnc bits? Ive been getting quite a bit from Precise Bits, IDC, Amana and Whiteside. I'm especially looking for extended overall length to carve necks and bodies.

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I had an Amana .5”x6” bit for necks. The bit was up to the task, my CNC most def not. I had the clearance and travel (6” clearance and almost 12” travel) but no where near the rigidity.*

If you have a good machine (linear rails, ball screws, thick aluminum or steel plates) I’m sure any major manufacturers’ XL bits will work for wood. In fact, I often bought used bits that were too dull for aerospace but worked on maple and mahogany just fine. There was an eBay seller back in the early naughts that had really good deals on very lightly used bits, but I doubt I could identify them now.

I recommend figuring out how to carve the heel separately and key them together. Having a bit stick out 1.5” on most desktop machines is the limit. More creates too much… I’m going to say, torque arm? Something like that. In any case it tests your machine’s rigidity WAY more to just have it stick out a an extra inch, let alone having the tip out 4” to carve an acoustic neck.

*All the twelve year old boys on the forum can stop suppressing their snickers now and have yourselves a good laugh now.


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Unfortunately I have a 65mm spindle so it can only do 3/8" bits but I have been thinking about upgrading to a an 80 mm spindle. I have found that the longer bits aren't as available as the 3" bits. I've also been trying to figure out a way to to carve the neck on it's side which probably isn't the best route. Now I'm on a path off carving the heel in two parts 75% with a 3" bit and possibly the balance of the heel with a longer bit. But it's not going to happen with a ER16 collet. I haven't begun to test out the deflection and or runout. I imagine it would be pretty significant.

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There are definitely builders who CNC carve their necks on the side.
I think I would pursue that option given the limitations of your machine which you’ve mentioned so far.

Dureo do you know of any? I would love to discuss their process for clamping and other details.

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I’m sorry I don’t know any by name but I’ve seen pictures in my internet travels, possibly on instagram.

Clearly an indexing system is needed for flipping the neck for the second side cut, such as a pin in the spoilboard at each end.

I might try a hold down method which attaches to the fretboard mating surface as that’s still flat after both cuts are finished. Maybe the super glue tape method to an aluminum angle beam.

Just thinking out loud. I haven’t needed to face this issue as I’m focused on electric necks.

I'll share an idea I have not yet tested. Repeat, NOT yet tested. It is on my list of things to try out.

I was thinking that, for most folks who are using CNC machines and are trying to carve necks, they are also using the CNC machine to make the fretboard, and using the CNC to drill indexing holes for placement of the fingerboard on the neck. They tend to be two holes, one to the left of the truss rod slot at one end, and the other to the right of the truss rod slot on the other end. If done right, those holes could be index holes for fitting the neck onto a 4 inch square, 20 inch long (or however long is needed) block securely mounted on the bed of the CNC. The neck would be on its side, indexing with holes in the side of the block. You can carve one side, then flip the neck end for end after you carve one side of the neck, and run each side as a different operation. You could index on those two holes, but also hold the neck in place with clamps placed on the headstock (carved during some other operation, while flat) with a ramp underneath, and on a piece of neck extension that you leave on until after the neck is carved. When I stack a heel, there is always a bit of a tail of neck wood that I have to cut off later; just leave that on until after carving is done. Again, if done right, you might have a little offset cleanup work to do, but not much.

If anyone tries this idea out, I would love to hear about the results!

Hi Don,

Ya I've been thinking about something along those lines as well. I want to do it with a vacuum jig to. I know even more engineering to figure out hahah. I just took a sweet Cad design course for vacuum fixtures and jigs so I think I might have a solution.

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Tell us more?

What is this course of which you speak?

Leo, Tom Dalia aka Frettie Mercury on Instagram offers CAD and CAM classes in Rhino. He also offers specialized classes as well such as vacuum fixture design. I took his Rhino Cad design class for Acoustic guitar and Electric guitar classes. Was a great experience. He also offers tutoring as well. I can't say enough good things about his classes. Tom is involved with the Looth Group as well. I found the classes really got me thinking about design perimeters which I hadn't done as much doing it old school via pencil and paper. To be able to do 3D modeling is amazing. As we all know technology has really changed some of the aspects of luthiery like Cnc, Lasers and 3D printing. Wether you agree or not they add a whole other dimensions to our tool sets.

https://www.instagram.com/frettiemercury/

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Thanks very much for that link, David.

Alignment dowels and Hippie tape. No clamping required.

I started making necks on a shapeoko xxl, but upgraded to the Stepcraft M1000 when a used one popped up on Marketplace. Both will cut the neck from the top in one operation. There isn’t a ton of excess z travel, but there is enough with 4” bits.

I get perfect necks with very little physical effort. It took me a long time to sort all this out-I couldn’t find anything online so had to come up with the process myself.

On the Stepcraft, I made a custom jig/bed the has dowels to hold the neck. The process is as follows.

1. I cut two necks from a solid block. this is cut from the side of the necks. I could use a bandsaw, but I cut the bottom of the necks flat on the cnc so the next step is easier. No vacuum or clamps, I just use Hippie woodcrafters double-sided tape.

2. Square up the Headstock with a handplane.

3. I cut the truss rod channel, carbon fiber reinforcement rods channels, and fretboard alignment pins in one operation. I use dewalt trigger clamps to hold the neck to a jig for this operation.

4. Here I use a 1/4” x 4” ballnose bit. Using the fretboard alignment holes, I flip the neck upside down and use Hippie tape to prevent it from lifting. The dowel rods prevent lateral movement, which is the main force here. This could be done with one cut file, but I run separate rough cut files for the heel, shaft, and headstock to save time. Then I run a finish pass over everything. I cut it just about 1 mm wide and 1 mm tall to allow for sanding later. I also leave plenty to do the dovetail joint later. I don’t attempt to cut that here due to variations in the body.

5. Then I cut the alignment holes in the back of the fretboard.

6. Flip the fretboard and hold it using the alignment hole pins just like the neck. I use 1/4” walnut dowel rods from Amazon. In one operation, I radius the fretboard, cut the perimeter, cut the abalone channels, and cut any other inlays.

7. I glue in all the abalone and inlays. Then I run another operation to cut the frets.

8. I then glue on the fretboard binding, but don’t bother sanding it.

9. I put it back on the cnc and rerun the radius shaping file, which smooths out the new binding and inlays. I have very minimal sanding aferward.

10. Fit neck to body.

11. After sanding the top of the neck flat to the body, I cut the headplate at a 15 degree angle on the miter saw and glue it to the headstock. In one operation, I then trim the headstock perimeter, cut out the tuner holes, carve inlays, cut abalone channels, and cut binding channels.

12. I cut the binding out of stock and glue it in place. Maple I cutout as one piece and ebony in multiple pieces. Ebony is more expensive and the seams are invisible. Maple is cheaper and shows seams like a sore thumb.

13. I put the fretboard on the neck and sand the sides smooth (this is why I cut it wide earlier).

It seems like a lot of steps, but I’m usually working on something else while it’s running. And I get my bits from bitsbits.com most often. No-name Amazon bits are junk.

$30 for 1/8" and smaller end mills is highway robbery! I have indeed gotten useless bits buying from no-name Chinese sellers, but also have gotten good ones. And even high quality American and Japanese shouldn't be more than $5-10 for the smaller sizes and $10-20 for 1/4". My go-to supplier is https://www.ebay.com/str/carbideplus

I'll check them out.

I get my fret bits from bitsbits. I haven't seen anyone else selling them. They cut a fret slot perfectly. I can press in the frets on the fingerboard before glueing it to the neck and it doesn't bow. Much easier this way for me.

I’ve had good luck with Amana and Whiteside too. For longer bits, I’ve picked up a few from ToolsToday and Elaire Corp. Both carry extended-length options that have held up really well for me.