Custom Build...Double Cut

[fretman_2]

I'll document my attempt at a custom design double cut based on the single cut MI59 design that I've done previously. The MI59 is based on the shape of a guitar from a September 1959 article in Mechanix Illustrated entitled "How to Make an Electric Guitar."

I haven't done a lacquer finish on a guitar in a while so that's what I'm going to attempt. I'm going to use brushing lacquer on this one since my spray facilities are very inadequate.

I'm using Minwax brushing lacquer purchased at Home Depot and StewMac Color Tone Vintage Amber and Medium Brown tints.

I'll cut both body and neck with my homebrew CNC machine. I hope to teach myself how to do the 3D profile on the neck, but short of that I'll CNC the neck outline and drill the tuner holes with it. I have both a rosewood and maple fretboard and I haven't decided which I'll use.

The body back is two pieces of maple and the top is a less than perfect flame maple, but it has some very interesting patterns. I used my CNC machine to edge the body back pieces so they could be joined. That worked great and gave me a perfect edge for gluing. I also did that on the top.

I'll use the CNC machine to cut and engrave the neck and control plates and possibly some other adornments. I know some of you guys feel that using a CNC machine is cheating. I'm not going to make a case for using CNC for guitar building in this thread. CNC is just one tool that I use. Most of this guitar will be finished by hand.

I also have a 2.5watt laser and I may use that to etch designs into the control and neck plates. That process will involve painting the plates with flat black paint, etching off the paint with the laser, then submerging the plates in a salt water bath, and electro-etching with DC current. If it works I'll document that process.

This is what I have in mind, but it could change as I get into the build.

This is a test on a remnant of the top. I probably won't go this dark because because the lacquer will amber up on its own in time.

Freshly CNC'd body. It took about an hour and a half to do. Settings were 50ipm feed and .05" depth of cut with a 40% step over. Those were very conservative settings in hindsight. I'll bump up to 70 or 80ipm with a 50% step over next time. I applied mineral spirits to pop the grain. The fuzzy edges were caused by the spiral upcut bit. A downcut bit would have left a cleaner edge, but a little sanding took care of the fuzz. Yes...the router is held tight to the CNC machine with a big hose clamp. The router will not move in the holder, but I do need to trim the excess.

A couple of coats of amber tinted brushing lacquer applied. It looks a little more yellow in this pic than in person.

 

[Skyjerk]

I like this double-cut better than the single-cut version

The only complaint I have about CNC is that I dont have one
I would definitely use CNC to improve the product and complexity of my inlay work, and it would be really nice to be able to produce consistent top carves.

That said, I'm not hurting for the lack of one. Its a tool and the end product is what its all about regardless of what tool was used to make it.

 

[Marty M.]

Using a CNC isn't any more cheating than using a template ..... in fact there are way more skills necessary to get a guitar made by a cnc than a template.....Anybody who thinks it is easy should learn how to do CAD, then learn a CAM software program, then lastly learn how to model a neck and body in 3D. Then compare all that to holding a router within a template and you'll see which one is " cheating".

 

[Skyjerk]

in fact there are way more skills necessary to get a guitar made by a cnc than a template....

I think it would be more fair to say there are many different skills needed to run CNC as opposed to way "more" skills.

Now if you can build a guitar from scratch without CNC, AND you can build with CNC, then you can say "way more"

 

[Marty M.]

I think it would be more fair to say there are many different skills needed to run CNC as opposed to way "more" skills.

Now if you can build a guitar from scratch without CNC, AND you can build with CNC, then you can say "way more"

I can and do....LOL.... so I guess I can...


One can take an unskilled person with decent hand to eye coordination, give them access to a bandsaw, a template, body blank, and a router, and they can turn out a body in a few hours. It may be great or not so great, but it is doable.

Take the template away and then that person then has to develop some better woodworking skills.

The same can't be said for giving them access to a cnc router without a lot more time spent behind a computer. There is a larger learning curve to working with software programs to achieve the same resulting simple body.

A template requires fewer skills and that's the whole idea behind them and the pattern bit/ overarm router. It is the basis to how manufacturing is simplified to produce products with a lower skilled labor force.


For the average person doing cnc at home I bet it takes at least 2x as long for a result since there is a debugging aspect that comes with the process. It's not a time saver for one -off builds, but for repetitive bodies and necks it is.

 

[Skyjerk]

I can and do....LOL.... so I guess I can...


One can take an unskilled person with decent hand to eye coordination, give them access to a bandsaw, a template, body blank, and a router, and they can turn out a body in a few hours. It may be great or not so great.

.

If the mark is "great" (and it certainly should be), an unskilled person is very unlikely to hit that mark. Templates are no guarantee of a good outcome. Looking at any number of build threads on this forum is proof enough of that. The only cure for that is experience and skill.

I'm not debating the value of CNC, nor am I making a claim that a CNC build requires less skill or is "cheating". It sounds like you are doing the opposite though and claiming CNC requires more skill than building without it.

If consistency is a measure of skill (and I believe it is) then it takes a lot of skill to produce guitars by hand, carved top guitars in particular, that have the same shape from one build to the next.

It takes a lot of skill to develop a 3D model and turn that into a working CNC design. I agree. I dont agree that it takes more skill. I've been working in IT for over 20 years as a UNIX engineer and network engineer. I use many different applications in both my personal and professional life, some of which involve 3D modeling. I do have a fair notion of the time and effort involved in mastering those apps, and I'm not going to concede that they take more skill.

They just take different skill.

 

[Marty M.]

If the mark is "great" (and it certainly should be), an unskilled person is very unlikely to hit that mark. Templates are no guarantee of a good outcome. Looking at any number of build threads on this forum is proof enough of that. The only cure for that is experience and skill.

I'm not debating the value of CNC, nor am I making a claim that a CNC build requires less skill or is "cheating". It sounds like you are doing the opposite though and claiming CNC requires more skill than building without it.

If consistency is a measure of skill (and I believe it is) then it takes a lot of skill to produce guitars by hand, carved top guitars in particular, that have the same shape from one build to the next.

It takes a lot of skill to develop a 3D model and turn that into a working CNC design. I agree. I dont agree that it takes more skill. I've been working in IT for over 20 years as a UNIX engineer and network engineer. I use many different applications in both my personal and professional life, some of which involve 3D modeling. I do have a fair notion of the time and effort involved in mastering those apps, and I'm not going to concede that they take more skill.

They just take different skill.

OK...different skills... we'll go with that. And for the record, I'm not talking set neck carved tops...I'm talking F style parts where you put a template on and go to town. This is probably the first place most people start out at. A set neck is way more complex. By the way, the cnc router gets one to the same point as the template/drill press. All the remaining tasks still need to be done by both methods.

You should get a cnc router in your shop.... then we can argue some more.....

 

[Skyjerk]

You should get a cnc router in your shop.... then we can argue some more.....

I'd love to, believe me. I have issues of space (which I could probably resolve) and then a bigger issue of money

someday...

 

[valvetoneman]

yeah but can you build an acoustic with a cnc, I also like changing things as I build, not sure if a cnc is easy to change on the fly

It's all horses for courses but I'd still like one or have some things made maybe

 

[Marty M.]

yeah but can you build an acoustic with a cnc, I also like changing things as I build, not sure if a cnc is easy to change on the fly

It's all horses for courses but I'd still like one or have some things made maybe

On my last few acoustics, I built and cut the rosette on the cnc. I arched the back braces to the required radius and cut out the initial pattern for the putting the assembly board together. I cut the spruce top and soundhole out with it. I cut out and drilled the two plywood forms for the Fox bender. Some tasks are better done on other equipment so those were employed. I carved the neck by hand, but could have done the shaft of it on the cnc. I would have had to do the neck on its side to do the whole thing, and I'm pretty fast with the carving, so that was a factor to just do it by hand. The fretboard was radiused, tapered, and drilled on the cnc, and lastly I routed the saddle slot, and carved /drilled the pyramid bridge with it. Lots of fun can be had.

The Peghead veneer was cut out and drilled on the cnc too. Sometimes just to keep my chops up, I'll do stuff with the cnc over by other methods. If you don't use it you lose it....

Sorry for the derail Fretman ,but the CNC can be awfully misunderstood.

 

[valvetoneman]

On my last few acoustics, I built and cut the rosette on the cnc. I arched the back braces to the required radius and cut out the initial pattern for the putting the assembly board together. I cut the spruce top and soundhole out with it. I cut out and drilled the two plywood forms for the Fox bender. Some tasks are better done on other equipment so those were employed. I carved the neck by hand, but could have done the shaft of it on the cnc. I would have had to do the neck on its side to do the whole thing, and I'm pretty fast with the carving, so that was a factor to just do it by hand. The fretboard was radiused, tapered, and drilled on the cnc, and lastly I routed the saddle slot, and carved /drilled the pyramid bridge with it. Lots of fun can be had.

The Peghead veneer was cut out and drilled on the cnc too. Sometimes just to keep my chops up, I'll do stuff with the cnc over by other methods. If you don't use it you lose it....


View attachment 276955


Sorry for the derail Fretman ,but the CNC can be awfully misunderstood.

doesn't sound like much would be gained imo, I cut my rosette out with a dremel and hole cutter base, my rosette was 2mm pieces of end grain ebony and maple, that's cut by hand and was quite quick as I'd already done that on a previous soundboard
alot of it is by hand, I like a Fox bender for bending ribs although my first 2 were on a bending iron and a sander thicknesser saves alot of time too

It's all good and whatever works for you is the most important thing

 

[fretman_2]

No problem with the derail Marty...very much welcomed in fact. I enjoy seeing what others have done with their machines. Beautiful acoustic build too!

On my last few acoustics, I built and cut the rosette on the cnc. I arched the back braces to the required radius and cut out the initial pattern for the putting the assembly board together. I cut the spruce top and soundhole out with it. I cut out and drilled the two plywood forms for the Fox bender. Some tasks are better done on other equipment so those were employed. I carved the neck by hand, but could have done the shaft of it on the cnc. I would have had to do the neck on its side to do the whole thing, and I'm pretty fast with the carving, so that was a factor to just do it by hand. The fretboard was radiused, tapered, and drilled on the cnc, and lastly I routed the saddle slot, and carved /drilled the pyramid bridge with it. Lots of fun can be had.

The Peghead veneer was cut out and drilled on the cnc too. Sometimes just to keep my chops up, I'll do stuff with the cnc over by other methods. If you don't use it you lose it....


View attachment 276955


Sorry for the derail Fretman ,but the CNC can be awfully misunderstood.

 

[fretman_2]

Mine's kind of on the big side Chris. Built large enough to accomodate CNC'ing necks. But I have in mind a smaller build that'll be mainly to do things like neck and control plates and smaller carves into aluminum and wood that will adorn my guitars. It's great to be able to CNC necks and bodies, but the real lure of CNC to me is the engraving and carving. Those things, in my mind, will make my guitars unique.

I'd love to, believe me. I have issues of space (which I could probably resolve) and then a bigger issue of money

someday...

 

[Skyjerk]

Mine's kind of on the big side Chris. Built large enough to accomodate CNC'ing necks. But I have in mind a smaller build that'll be mainly to do things like neck and control plates and smaller carves into aluminum and wood that will adorn my guitars. It's great to be able to CNC necks and bodies, but the real lure of CNC to me is the engraving and carving. Those things, in my mind, will make my guitars unique.

The biggest appeal for me with CNC is inlays. Cutting pearl and the pockets they go into. Fretboards, headstocks, etc. I'd LOVE to get a smallish machine that could do those things. Space for a machine that could do that wouldnt be that big an issue. Leaves me with the money hurdle yet to jump over

 

[fretman_2]

I agree...CNC is not a time saver for one off designs. The aspect of getting the design into the computer adds a lot of time to the whole process. But now that I've, more or less, settled on a design for my guitars, the CNC will cut out the same body over and over and over.

I can and do....LOL.... so I guess I can...


One can take an unskilled person with decent hand to eye coordination, give them access to a bandsaw, a template, body blank, and a router, and they can turn out a body in a few hours. It may be great or not so great, but it is doable.

Take the template away and then that person then has to develop some better woodworking skills.

The same can't be said for giving them access to a cnc router without a lot more time spent behind a computer. There is a larger learning curve to working with software programs to achieve the same resulting simple body.

A template requires fewer skills and that's the whole idea behind them and the pattern bit/ overarm router. It is the basis to how manufacturing is simplified to produce products with a lower skilled labor force.


For the average person doing cnc at home I bet it takes at least 2x as long for a result since there is a debugging aspect that comes with the process. It's not a time saver for one -off builds, but for repetitive bodies and necks it is.

 

[fretman_2]

I've been working on designing a machine that'll cut an area around 8X8 or so. Stout enough to cut or carve aluminum. All I've purchased for it so far is the Arduino Uno controller. I'll buy the rail, gShield and motors piece meal...as I get gig money...LOL.

The biggest appeal for me with CNC is inlays. Cutting pearl and the pockets they go into. Fretboards, headstocks, etc. I'd LOVE to get a smallish machine that could do those things. Space for a machine that could do that wouldnt be that big an issue. Leaves me with the money hurdle yet to jump over

 

[Marty M.]

Two days ago I finally dismantled my first cnc that I built from the ground up. It was big enough to do necks and bodies. The linear rails were aluminum angle, hex, and roller skate bearings on drill rod. The sheet goods were 3/4 thick plastic sheet. Back 10 -15 years or so, the first commercial machines employed more plastic then aluminum. Anti backlash screws were allthread and home made delrin nuts. I learned to write gcode programs on it and it really got my interest up. As the CAD and CAM developed, and the cost of commercial machines came down, the machine got mothballed. It really was pretty accurate for what it was. I have a few sets of linear guides here and really want to do a dedicated neck carving cnc. I had purchased a Shapeoko2, but found that was more like a toy than a machine. The new machine may happen this winter.... just depends on what else is going on.

 

[fretman_2]

Two days ago I finally dismantled my first cnc that I built from the ground up. It was big enough to do necks and bodies. The linear rails were aluminum angle, hex, and roller skate bearings on drill rod. The sheet goods were 3/4 thick plastic sheet. Back 10 -15 years or so, the first commercial machines employed more plastic then aluminum. Anti backlash screws were allthread and home made delrin nuts. I learned to write gcode programs on it and it really got my interest up. As the CAD and CAM developed, and the cost of commercial machines came down, the machine got mothballed. It really was pretty accurate for what it was. I have a few sets of linear guides here and really want to do a dedicated neck carving cnc. I had purchased a Shapeoko2, but found that was more like a toy than a machine. The new machine may happen this winter.... just depends on what else is going on.

 

[fretman_2]

Progress is slow, but I hope to finish this guitar by Spring. I CNC'd the neck this weekend. Truss rod channel fit perectly, but neck was too tight to the body so I'll have to sand a little off the sides of the neck to get it to fit. Neck and neck pocket dimensions are exactly the same. I used conventional cutting to cut the neck and I should have used climb, but that still wouldn't have given me any room for the finish on the neck. Either enlarging the neck pocket a few thousands or reducing the neck a few thousands would have compensated...but just how much? Marty...how much smaller or larger do you make your neck pockets-necks when you CNC to compensate for finish?

At the top of this thread I said I would brush on the lacquer. Well...I wound up thinning it 50% and spraying on with a prevail sprayer. There's probably 5 coats or so of tinted lacquer and another 5 coats of clear. Tint is Colortone vintage amber.