curtisa

I meant, you appear to have used Hiwin equivalent rails/bearings on your build. Mike.Mara is looking at using supported rail (coded 'SBR' by Chinese auction sites) which may have limitations on which way around they are oriented for maximum strength. My comments referred to installing the SBR rails in the same configuration as your method to give maximum strength to a product that may already have inherent weaknesses.

For all I know the recommendations may have originated from people poo-pooing the idea of using those rails for a machine being designed to mill steel. Your scope is a bit more relaxed than that, so it may not be a problem in the long run. Anyone trying to mill steel on a MDF machine is likely to destroy the frame and gantry before the bearings give way. As Mike has suggested - one rail top, one rail under. You're also using profiled rails and carriages, which are designed to withstand more force in directions other than perpendicular to the bearing mounting face. Although, the same principle applies to the supported rails that @Mike.Mara is looking at. - they're probably not as resilient as the Hiwin types, but mounting over and under will maximise their strength and stability given the circumstances.

Router with pattern bits and a straight edge to follow will give you pretty good straight cuts with a perpendicular edge, which will get you out of trouble for most of the major components. Most of the parts in a CNC are in pairs, so once you've made one of a widget, you can use that widget as a template for the next one. Mike's printed labels as templates is a good idea, whether you work with Al or MDF, provided you can verify your printer is generating accurate images first. MDF to begin with. Your picture of the two bed designs is a good starting point. The MDF version can be stiffened up a lot by adding cross members as you've done with the Al version. When I was researching my build, the comments I saw floating around about running those types of rails and bearings in the orientation you have done made me a bit leery of using them. The impression I got was that the open-sided bearings that fit those rails will give better results when the forces pressing down on them are mostly in the opposite direction to the open side. The suggestion I saw was that if you swing the rails around 90 degrees so that the bearing runs on top of the bed it may be better in the long run, preventing the bearing openings from stretching under the forces and static weight of the gantry.

Yep. Perhaps need more boundaries laid out for the build limitations. If it's mostly Al with a bit of MDF then the difference in going to 100% Al will be negligible (assuming the builder can machine it properly). If cost is a concern then minimise the use of the expensive stuff and stick with MDF for the majority of the components.

I was actually going to suggest the opposite. If the intention is to make an a machine capable of acceptable precision at rock bottom prices, then the Al extrusion framing is probably overkill. Cutting the extrusions squarely for the home builder will be difficult unless they have access to a decent quality drop saw with a metal cutting blade. What about limiting the metalwork to only the rails and bearings?

Sounds good. I'd also add a square, router with pattern-following bits, brad point and forstener drill bits (if we're still looking at an MDF-framed machine), steel ruler big enough to cover the longest edge, a compass or trammel. Most of these items a DIY guitar builder will likely have access to anyway. If you can keep it within the realm of 'doable by somebody with a modestly equipped workshop', it is more likely of success. The added cost of third-party cutting and shaping is likely make it a non-starter compared to buying a CNC6040 off eBay. Perhaps the JGro CNC might be a good basepoint to get some ideas from?

I knew the parport was supported in Mach3, just wasn't sure if a plugin PCI parport would cause issues. I'm not pushing a spindle around over large distances for production runs, so blisteringly fast speed isn't big on my list of priorities and I can live with direct parport control for now.

Only as I've said above - factor in how the DIY builder will cut and drill the necessary components that may require a certain degree of minimum tolerance. The two endplates with the bearing mount drill holes ,and ensuring baseplate extrusion is cut squarely at the ends where the endplates butt up against are good examples.

My gut feel is that if you want to design a CNC intended for DIY-ing by the guitar building community, irrespective of what it is made from, you'll probably need to make it as plug and play-able as possible. The person making it is unlikely to have access to another CNC or milling setup capable of making the parts with sufficiently tight tolerances that make up the CNC (otherwise they wouldn't be making it!). Factor in how accurate is accurate enough when measuring, making and assembling the various components, and what the minimum tool set is required in order to achieve it. Most DIY guitar builders will also freely admit that their electronics skills are limited to following wiring diagrams, with little understanding as to why things are done the way they are done. Getting the steppers, power supplies, limit switches, drivers, interfaces etc working together will require a certain amount of knowledge as to how to make it all go, and what to look for when it doesn't. The unitised nature of larger/more elaborate control setups also place an additional demand on wiring abilities - knowing what gauge of wire to use for steppers to minimise voltage drop, what insulation level for the incoming mains, the importance of earthing, the dangers of exposed mains connectors are all things people who only DIY guitars are unlikely to know about or understand. If you can specify an all-in-one self contained control system it's likely to work safely right from the get-go for nearly everyone. There's also only two CNC motion control applications (that I'm aware of) out there - LinuxCNC and Mach. LinuxCNC is free but will require a willingness to play with Linux. It's also not necessarily a solution that works straight out of the box either (I've installed LCNC onto two PCs - one worked flawlessly from the start, the other took lots of experimentation, researching forum topics, hunting for BIOS settings, writing scripts, modifying boot parameters etc to get it to play nicely). Mach may be slightly more user friendly and runs on Windows without too many foibles, but will set the user back a couple of hundred smackers

Hell of a challenge you're taking on there, @Mike.Mara. I'm currently at the tail end of rebuilding my CNC too (not my first foray into CNC, but certainly my first build) and I echo most of what @MiKro has to say about setting the primary goals and limitations. The machine I'm putting together is about 600mm x 450mm x 100mm cutting size. Frame is aluminium (or aluminum if you prefer) 30-series extrusion plus some 10mm Al plate for other components, gantry is the single Y-axis drive variety with the underslung crossbeam, Hiwin-type linear rails, 1605 ballscrews, NEMA23 3A steppers, 1.5kW spindle with VFD, generic M542 drivers. Mike's estimate of $2.5K AUD is not far from what I'll likely end up spending once it's all done, including some kind of control box to house all the electrickery stuff, 90% of which was purchased from China and assembled from scratch. Rigidity, slop and backlash is good, with the exception of the Z axis carriage, which was my own fault for purchasing a prefab unit in the hopes it would save me some time and money by not having to make one. Two unsupported 16mm rails with one bearing block per rail just isn't enough to take the weight of the spindle, and the whole thing visibly wobbles in the Y direction. Lesson learned - I'll be rebuilding a new Z axis from scratch using profiled rails with two bearing carriages per rail like I should have done to begin with. I already use LinuxCNC on a PC with the baby CNC3020 I bought a couple of years ago, rather than Mach3. As Mike suggested, I initially thought I was going to struggle finding a PC with a parallel port, but the $15 PCI parallel port card I bought from eBay has worked perfectly. I'm not sure if they're as effective with Mach3/4. If you work slowly and incredibly carefully, and are willing to prematurely age some router bits, aluminium will cut with a hand router. I've made up several adapter plates for the ballscrew bearing supports by creating templates out of acrylic plastic on the CNC3020, cutting the 10mm Al plate as close as possible to the dimensions of the plastic template and finishing off the Al shaping using a router fitted with a template bit. I could have used the CNC3020 to directly mill the Al plates, but the process is incredibly slow and the use of cutting lubricant makes it messy too. That's something you may want to consider if you're looking at making a machine out of MDF. It might be strong enough to mill aluminium, but as soon as you start spraying cutting fluid onto the workpiece, the MDF is going to soak it all up in the process.

Moved to the Tech Area -> Solid Body and Bass Chat for better house keeping.

Not sure what you mean. The candle wax should prevent the blade from getting jammed in the slot, making it easier to cut the slot and remove the saw when finished. Any sawdust that works its way into the saw teeth should be easy to remove using a stiff brush.

Replicators.

A backside or a mandolin? Nice job, Scott. Don't misplace it though; it's so teeny.

Lubricate your saw blade with candle wax every few slots. It will cut much easier without binding in the wood.

Brass gets a patina. Gold gets spandex.

Coulda sworn in a past life I saw you mention that you'd never use stainless steel frets. Looking RADalicious.

Not sure what you mean by 'separate from the guitar'. Have you got a Washburn model that we can look up? I imagine that the wire is already connected to the bridge. All you have to do is connect the other end to the nearest ground inside the guitar. This is typically made to the case of the volume pot, the case of the tone pot or the ground lug on the output jack for example.

The pre-All Access Neck Joint that Ibanez used to do on their Jem models is pretty slim compared to the depth of the heel. I've never heard of the basswood-bodied Jem being weak at the heel, so in all likelihood your Yellowheart body will survive with 5/8" remaining under the 7/8" deep pocket just fine. If you're still worried about the integrity of the joint on a body 1 1/2" thick, you can always split the difference and put a 3/4" neck heel into a 3/4" pocket and keep 3/4" of meat on the body underneath. On first glance, your nominal 7/8" heel actually seems pretty stout. While I don't have any guitars in my posession that might be classed as 'traditional', none of my bolt-on instruments have a neck heel any thicker than 3/4" excluding the fretboard anyway.

Most of the time it is convenient to route after the body is cut. You can tweak the neck pocket alignment to suit the body before committing router to wood. But that assumes you're routing a square pocket and only need to rely on the flat face of the unfinished body. In your case, where you want to tilt the pocket to introduce neck angle, it might be easier to route the pocket first and then align the body shape to the pocket. You can also take advantage of the body still being one giant rectangle of wood at this point to locate and/or route the pickup cavities and tailpiece positions. Provided your blank has enough excess it should have sufficient leeway to allow slight shifts of the outline to match the neck pocket. Are you referring to 7/8" thickness of the neck that sits in the pocket, a pocket depth of 7/8" or 7/8" thickness of wood remaining on the body once the pocket has been cut? Depending on your definition of the heel being 7/8", and in combination with your body thickness, this will dictate the remaining two dimensions. Don't forget that your neck thickness will also include the fretboard on top (+1/4" or so). Nah. I'm just a hobby builder with just enough experience to be dangerous.

Reducing the thickness by 1/4" saves you approx 15% weight. I don't know what a Yellowheart Explorer is likely to weigh but it appears that Yellowheart is twice as heavy as Basswood and about 1.3x as heavy as Mahogany. I predict it will still be a back-breaker even with the thinner body. Is chambering a possibility? You can get the weight down a lot by performing liposuction on the non-structural parts and still keep your 1 3/4" body thickness if you wish. You need to know what your neck dimensions will be first. You're putting the cart before the horse by stipulating a required pocket depth before knowing what the neck heel size and shape will be and how it needs to interact with the hardware you're going to install. It shouldn't be discounted though. At most you're only going to need a couple of degrees of tilt off horizontal. It's an easy and unobtrusive way of achieving the required angle on a bolt-on. Certainly easier than trying to perform other operations that will give you the required angle. A shim that covers the full face of the neck pocket will still give you full contact between heel and body if you're concerned about any tonal deficiencies that may result (although any tonal issues resulting from the use of shims this would be hard to quantify and prove under normal circumstance anyway). This would be my preferred option over angling the heel. Your method of angling the router template by shimming is the easiest way to achieve it, and should be easy to manage if the body outline is cut after the neck pocket is done to keep as much square body surface available to shim the template against. As soon as you cut out cutaways and body edges you'll loose a lot of reference surfaces to key against, so in this case it's probably better to cut the pocket first. There are other ways to cut an angled pocket that don't rely on the body face as a reference edge (the Myka Neck Pocket Jig is a good example), but it's a lot more work to create the required jig up front. A couple of degrees off perpendicular isn't going cause any issues. Angling the pocket avoids the issue of a gap at the back of the pocket. Although there are ways of disguising any potential gap that can occur by angled shims in a square pocket - a fretboard overhang, having the neck pickup route right up against the neck pocket (Ibanez do this all the time on their S and RG models), hiding any gap with a pickup ring or scratchplate etc

I suspect you're missing a ground connection to the strings via the bridge. If you have a guitar lead with a metallic barrel shell, try plugging it in to your guitar and amp. If the hum and pops stop occuring when you have one hand on the metal shell of the guitar lead, you've got a missing ground inside the guitar.

Does the guitar generally buzz and hum more than expected? Is the volume pot shaft plastic or metal? I assume the volume knob itself is metal. Is the case of the volume pot connected to ground?

Do you mean you get a pop noise from the amp when you touch the volume pot, or you receive an electric shock?

Moved to the Tech Area -> Electronics Chat for better housekeeping.