Official Luthiers Forum! :: View topic - Any of you CNC a fret board, but not the fret slots?

I don't mind how long it takes to do the fret slots on the cnc. I'm not a production shop. I cut the slots .01" deeper than the fret tang and follow the radius of the fretboard along the length of the slot.

Although it takes a few minutes to sand off the tooling marks...it really doesn't add up to more than a few thousands sanded off.

In Solidworks I just draw the fret lines in position and then make short extruded surfaces in order to have something to import into MasterCam.

My dots reach down .1" from the raw blank surface. I glue the dots in and cut whatever radius I want. Fret slots are the last op.

I'd cut the slots first so you can confirm that the inlays will line up with the fret slots.

We inlay, then radius, then cut slots on the machine, with the fretboard already on the fully carved neck.

You can draw the lines in a Solidworks sketch but unless you convert those lines into SOME kind of surface geometry they won't appear in MasterCam using the parasolid, or step formats.

Blain there are some real advantages to cutting the slots with CNC provided that your rig is tight and accurate.

David Collins has been doing a study for nearly as long as I have known him where he tooled up and measures the fret spacing on as many guitars of interest as he can. The study will be published at some point but for now what I want to say is that errors in slot spacing are very common to the point where they are the norm... unfortunately... I say unfortunately because many of the errors detected and charted in his database of hundreds of instruments now are far enough off that the difference is audible to the listener. Or, more simply put.... these fret spacing errors are often bad enough even on iconic instruments worth tens of thousands of dollars that the instrument does not sound in tune when it should....

My boards were mostly, not all, but mostly made on a CNC by John Watkins and some of mine are now in the database. The errors detected in these Watkins boards are the lowest error rate David has ever measured. Not tooting my own horn because I didn't make the boards but what I am saying is that if the accuracy of CNC is available to you why not exploit it to make the best use of the accuracy as a competitive advantage?

By the way this study also produces a digital fingerprint if you will and can definitively define where an instrument was made and when as well because of the way f*ctories were tooled up with gang saws, etc. The rule of 18 etc. and the errors in the manufacturer's tooling leave a permanent view into where, when, and if the records exist perhaps even by who the instrument was made. Forgery detection - you bet!

OTH some of the errors that we have seen on boards by small builders who slot their own boards are also very audible and measurable and in some instances are as bad as any others measured.

If I had a CNC rig I'be be slotting everything in the house, nothing would be safe....

I think you misunderstand, John.

You can draw the lines in a Solidworks sketch but unless you convert those lines into SOME kind of surface geometry they won't appear in MasterCam using the parasolid, or step formats.

So....I draw the fret positions as line and then extrude them....just to turn them into surfaces.

Like so.....

Author:	Blain [ Sun Dec 15, 2013 12:43 am ]
Post subject:	Any of you CNC a fret board, but not the fret slots?
I'm planning to CNC the fret board radius and some inlay on the fret board. Also possibly the profile. But I was planning on just cutting the fret slots on the table saw, since my setup for cutting slots is already fast and easy. I wanted to see how many of you do not cut the fret slots on CNC and what is your process? Do you just do the math and add a little extra for the depth of the slots to account for finish sanding at the end or do you come back after putting the radius to hand cut the slots a little deeper if needed? Since I cut the frets slots on the table saw, I would have to put the radius'd side down. So I would think cutting the slots first would make more sense to avoid making a special jig to hold the radius'd fret board face down. For those that use a hand held fret saw, I understand that it would make more sense to cut the slots afterward since the bottom of the fret board would be down and thus flat. Also do you find it best to cut the inlay pockets on the flat board (pre radius) or after radius? I know these are simple and stupid questions, but I just want to make sure there's not an "ah ha" moment that I'm just missing that would make this easier.

Author:	Marzano San [ Sun Dec 15, 2013 3:29 am ]
Post subject:	Re: Any of you CNC a fret board, but not the fret slots?
I first rout the radius on my fretboards, after that the fretslots and inlay pockets info on cutting fretslots on CNChere

Author:	cbrviking [ Sun Dec 15, 2013 12:06 pm ]
Post subject:	Re: Any of you CNC a fret board, but not the fret slots?
I use pre-slotted boards and just profile and make the dot marker pockets on the CNC.

Author:	Blain [ Sun Dec 15, 2013 1:11 pm ]
Post subject:	Re: Any of you CNC a fret board, but not the fret slots?
Jamie, So the pre-slotted boards are usually deep enough to where after you profile, you don't need to add depth to the slots? Or are you the one pre-slotting these boards and just adding extra depth to make up for the profiling? If so, how much extra are you adding to figure for profiling and sanding afterwards?

Author:	Parser [ Sun Dec 15, 2013 7:19 pm ]
Post subject:	Re: Any of you CNC a fret board, but not the fret slots?
I inlay, then radius, then slot, then profile... Slotting on the CNC is pretty slow for me, but I usually do some sanding or something else while it is running. Trev

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Author:	Blain [ Sun Dec 15, 2013 7:50 pm ]
Post subject:	Re: Any of you CNC a fret board, but not the fret slots?
Maybe I need to just give slotting a try on the CNC. It's just so quick and easy on the table saw that I hate to do it any other way. But, doing it on the CNC would ensure that everything is laid out together.....

Author:	John Sonksen [ Sun Dec 15, 2013 9:58 pm ]
Post subject:	Re: Any of you CNC a fret board, but not the fret slots?
I was thinking of trying to figure out the formula I'd need to drop into solidworks and how to input it for slotting, but it would probably just be easier doing it on the table saw like others have said. Modeling a compound radius board in solidworks is ridiculously easy though, fun stuff.

Author:	Stuart Gort [ Mon Dec 16, 2013 5:42 pm ]
Post subject:	Re: Any of you CNC a fret board, but not the fret slots?
I don't mind how long it takes to do the fret slots on the cnc. I'm not a production shop. I cut the slots .01" deeper than the fret tang and follow the radius of the fretboard along the length of the slot. Although it takes a few minutes to sand off the tooling marks...it really doesn't add up to more than a few thousands sanded off. In Solidworks I just draw the fret lines in position and then make short extruded surfaces in order to have something to import into MasterCam. My dots reach down .1" from the raw blank surface. I glue the dots in and cut whatever radius I want. Fret slots are the last op.

Author:	Blain [ Mon Dec 16, 2013 6:59 pm ]
Post subject:	Re: Any of you CNC a fret board, but not the fret slots?
Thanks Stuart. I think you've convinced me to go ahead and start slotting on the CNC. I'm not a production shop either so I don't really mind it taking longer either. I looked up some bits on precise bits, and they're really not that much as long as I can get them to last a while.

Author:	Sheldon Dingwall [ Mon Dec 16, 2013 7:03 pm ]
Post subject:	Re: Any of you CNC a fret board, but not the fret slots?
I'd cut the slots first so you can confirm that the inlays will line up with the fret slots. We inlay, then radius, then cut slots on the machine, with the fretboard already on the fully carved neck.

Author:	Hesh [ Mon Dec 16, 2013 7:32 pm ]
Post subject:	Re: Any of you CNC a fret board, but not the fret slots?
Blain there are some real advantages to cutting the slots with CNC provided that your rig is tight and accurate. David Collins has been doing a study for nearly as long as I have known him where he tooled up and measures the fret spacing on as many guitars of interest as he can. The study will be published at some point but for now what I want to say is that errors in slot spacing are very common to the point where they are the norm... unfortunately... I say unfortunately because many of the errors detected and charted in his database of hundreds of instruments now are far enough off that the difference is audible to the listener. Or, more simply put.... these fret spacing errors are often bad enough even on iconic instruments worth tens of thousands of dollars that the instrument does not sound in tune when it should.... My boards were mostly, not all, but mostly made on a CNC by John Watkins and some of mine are now in the database. The errors detected in these Watkins boards are the lowest error rate David has ever measured. Not tooting my own horn because I didn't make the boards but what I am saying is that if the accuracy of CNC is available to you why not exploit it to make the best use of the accuracy as a competitive advantage? By the way this study also produces a digital fingerprint if you will and can definitively define where an instrument was made and when as well because of the way f*ctories were tooled up with gang saws, etc. The rule of 18 etc. and the errors in the manufacturer's tooling leave a permanent view into where, when, and if the records exist perhaps even by who the instrument was made. Forgery detection - you bet! OTH some of the errors that we have seen on boards by small builders who slot their own boards are also very audible and measurable and in some instances are as bad as any others measured. If I had a CNC rig I'be be slotting everything in the house, nothing would be safe....

Author:	John Sonksen [ Mon Dec 16, 2013 9:04 pm ]
Post subject:	Re: Any of you CNC a fret board, but not the fret slots?
Stuart Gort wrote: I don't mind how long it takes to do the fret slots on the cnc. I'm not a production shop. I cut the slots .01" deeper than the fret tang and follow the radius of the fretboard along the length of the slot. Although it takes a few minutes to sand off the tooling marks...it really doesn't add up to more than a few thousands sanded off. In Solidworks I just draw the fret lines in position and then make short extruded surfaces in order to have something to import into MasterCam. My dots reach down .1" from the raw blank surface. I glue the dots in and cut whatever radius I want. Fret slots are the last op. So Stuart, do you go so far to do a mid-plane, cut extrude in solidworks, or are you saying you do an extrusion from the fret line impinging into the fret board, and it's just a matter of using the right thickness cutter to get your properly sized fret slot, following the middle of the line you placed?

Author:	Stuart Gort [ Tue Dec 17, 2013 12:55 am ]
Post subject:	Re: Any of you CNC a fret board, but not the fret slots?
I think you misunderstand, John. You can draw the lines in a Solidworks sketch but unless you convert those lines into SOME kind of surface geometry they won't appear in MasterCam using the parasolid, or step formats. So....I draw the fret positions as line and then extrude them....just to turn them into surfaces. Like so.....

Author:	Stuart Gort [ Tue Dec 17, 2013 1:08 am ]
Post subject:	Re: Any of you CNC a fret board, but not the fret slots?
Sheldon Dingwall wrote: I'd cut the slots first so you can confirm that the inlays will line up with the fret slots. We inlay, then radius, then cut slots on the machine, with the fretboard already on the fully carved neck. I just finished developing a similar technique for my new neckthrough. The older method works well too though the entire fretboard is cut prior to gluing. Note on my vacuum fixture for the older process there are four little slots nestled in there with the vacuum grooves. I lay four steel pins on their sides in those slots. There are also four corresponding slots on the fretboard itself. In this way, the part is utterly registered to the tool and can come on and off the tool any number of times maintaining PERFECT registration. When I make the necks I also include these registration slots. When gluing the fretboard to the neck I use wooden dowels in the slots and the fretboard gets glued in perfect position. This is the easiest way I could figure to maintain the model integrity throughout the gluing process. I do the same thing on the headstock facings.

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Author:	Andy Birko [ Tue Dec 17, 2013 9:49 am ]
Post subject:	Re: Any of you CNC a fret board, but not the fret slots?
Stuart Gort wrote: You can draw the lines in a Solidworks sketch but unless you convert those lines into SOME kind of surface geometry they won't appear in MasterCam using the parasolid, or step formats. Somewhat of a thread hijack but this brings up something interesting to me that I hadn't really thought of before but have been dealing with for a while. I use an integrated CAM system, VisualMill for Solidworks so when I'm drawing tool paths like fret slots, I can use 2D or 3D sketches directly in solid works. I like this because I can use all of SolidWork's tools for 2D and 3D sketches and do extensively to control my tool paths. As it is, I do the same thing that Stu does to draw the elliptical or arced lines on the actual fretboard but then I convert to a 3D intersection curve for the actual tool path.

Author:	RandK [ Tue Dec 17, 2013 10:16 am ]
Post subject:	Re: Any of you CNC a fret board, but not the fret slots?
Sheldon has a really good method to go post-glueup. I drill the backside for my positioning dowels Radius Inlay pocket Profile nut end and sides (for binding) Fret slot (saves cut inches on the bits over doing the whole blank) I use delrin dowels between the FB and neck. If I need to cook it off, the dowels slice easily with my spatula and some out cleanly.

Author:	L. Presnall [ Tue Dec 17, 2013 10:24 am ]
Post subject:	Re: Any of you CNC a fret board, but not the fret slots?
Hesh wrote: Blain there are some real advantages to cutting the slots with CNC provided that your rig is tight and accurate. David Collins has been doing a study for nearly as long as I have known him where he tooled up and measures the fret spacing on as many guitars of interest as he can. The study will be published at some point but for now what I want to say is that errors in slot spacing are very common to the point where they are the norm... unfortunately... I say unfortunately because many of the errors detected and charted in his database of hundreds of instruments now are far enough off that the difference is audible to the listener. Or, more simply put.... these fret spacing errors are often bad enough even on iconic instruments worth tens of thousands of dollars that the instrument does not sound in tune when it should.... My boards were mostly, not all, but mostly made on a CNC by John Watkins and some of mine are now in the database. The errors detected in these Watkins boards are the lowest error rate David has ever measured. Not tooting my own horn because I didn't make the boards but what I am saying is that if the accuracy of CNC is available to you why not exploit it to make the best use of the accuracy as a competitive advantage? By the way this study also produces a digital fingerprint if you will and can definitively define where an instrument was made and when as well because of the way f*ctories were tooled up with gang saws, etc. The rule of 18 etc. and the errors in the manufacturer's tooling leave a permanent view into where, when, and if the records exist perhaps even by who the instrument was made. Forgery detection - you bet! OTH some of the errors that we have seen on boards by small builders who slot their own boards are also very audible and measurable and in some instances are as bad as any others measured. If I had a CNC rig I'be be slotting everything in the house, nothing would be safe.... Hesh! Now THERE'S a guy you don't hear from every day! How are you doing? I just re-read all the articles on your site last month. Always a good review since I'm building infrequently these days.

Author:	John Sonksen [ Tue Dec 17, 2013 8:17 pm ]
Post subject:	Re: Any of you CNC a fret board, but not the fret slots?
Stuart Gort wrote: I think you misunderstand, John. You can draw the lines in a Solidworks sketch but unless you convert those lines into SOME kind of surface geometry they won't appear in MasterCam using the parasolid, or step formats. So....I draw the fret positions as line and then extrude them....just to turn them into surfaces. Like so..... ahh, haven't done anything like that yet. All I've done so far is renderings, next term I'll get to the CAM part of things. Interesting that you render a solid for where you want material removed, I guess I'll find out about that soon enough.

Author:	RTurner [ Sat Dec 28, 2013 6:25 pm ]
Post subject:	Re: Any of you CNC a fret board, but not the fret slots?
One clear advantage of milling the fret slots is doing closed ended slots, even if you're going to glue on binding. In just wood 'boards, you have self-bound fret slots; with binding, you have protection from getting binding glue into the slots. We set up to do 12 fingerboards at a time on our Techno-Isel machine. I personally really love setups where I can start the thing up and go do something else for a good long while. We'll have programs to run 1 part, 3, or 12.