Hello
Can i use cap head screws instead of low profile screws ?

 

Hi,

I have a quick question. I was following the instructions here to assemble my LEAD Machine: (around 30 minute mark). Getting to the point of mounting the Y-axis drag chain and I realized the threaded hole on the 20x40 is in the top, not the bottom. Does it matter if I use the top one instead of the bottom one in the video?

 

Hi all, I'm new to all this and about to pull the trigger on a Lead machine. Doing my research and this was the first post I've read that's relevant to my imagined use case. I'm a repair tech in a guitar shop and will eventually be using it for custom builds but want to start off with simpler builds like speaker cabs, guitar stands, basic sheet good stuff. I would also like to use the machine unpowered at times as an overhead router for quick guitar mods like battery cavities, enlarging pickup routes, larger bridge routes, etc. It seems like a much quicker/more accurate operation than setting up the plunge router, finding or making a routing template, stripping the guitar parts... basically relying on locking stops in the rails to set my dimensions.

So with that in mind a couple questions. How well will free hand plunging work? I'm assuming the spindle stays put while the z stepper is not under power. Is there room on that part of the assembly for vertical lock stops? Handles? Will there still be too much resistance without power to move the spindle manually through cuts?

Am I crazy or just ignorant?

 

Had a feeling that was the case.

 

But you could send the code for a move - ie use the stepper motors to move the router around while cutting. Would be a bit slower than hand routing with a template. You would probably find it's not that difficult to programme say a pocket, line the workpiece (guitar body?) up and clamp it and then run the code to cut the pocket. Drawing the design on computer would be a quicker than cutting a template, and probably quicker to find again if you wanted to do it again in future.
Alex.

 

Looking at the drawing I should be able to quickly detach the nut blocks from the gantry plates (and try not to lose the washers). The Z screw is the hang up then. It would be nice to have some resistance while plunging the spindle so I suppose I can unlock the coupling up top and leave the Z screw nut block engaged.

 

My plan was to use stops in the rails to set my boundaries rather than mess with templates.

 

But for the sort of jobs you described it really wouldn't be difficult to programme the machine - your drawing would define the boundaries - including the depth.
Alex.

 

That is a goal, eventually. I won't feel comfortable putting a customers guitar under the tool until I have a good bit of programming experience with it.

 

Another advantage would be that you don't have to have anything touching the surface of the guitar.
Alex.

 

I'm with Alex & Peter in thinking that manually pushing around the gantry is a just generally a Bad Idea. Aside from the problems mentioned, the gantry is going to want to rack itself because you're going to have trouble pushing both sides evenly. Also, while those nut blocks will come off easily, I can tell you from experience that they're a whole lot more challenging to get back on again & require really tiny fingers.

If, however, you're dead set on the idea & willing to go out of your way to achieve it, here are a couple thoughts:

- With a heavy spindle (my 80mm water-cooled job, for instance) the Z will just barely stay up when unpowered. Putting just a little force will gently lower it. Raising it manually, on the other hand, is a struggle - especially if you're having to reach across the machine bed to do it.

- The X & Y axes will take an uncomfortable amount of force to move around manually. The only way I can see it working is to replace the leadscrews with ballscrews, which will glide far more willingly. I don't know if this is a mod anyone has tried or documented yet. This would also lessen the chances of racking the gantry, but wouldn't necessarily eliminate it. You might still have to find some way to reinforce the structure to keep it rigid.

- You might (strictly theoretically) be able to address the racking by coupling the two leadballscrews with pulleys and a timing belt, keeping both screws turning in sync. Maybe.

- Bear in mind I haven't actually worked with ballscrews or belt drives before.

- If you did couple the gantry screws (even if you stuck with leadscrews) you could potentially put on hand cranks and run the machine like a manual mill. You may find that you'll have to crank awfully fast, though, unless you replace the standard screws with something with a steeper pitch or more starts. I built my first machine (an XY table with Z on a fixed gantry, which made things easier) with handcranks, and eventually pulled them off in frustration (and because they kept snagging anything in reach when the steppers were running).

And, again, I really don't think this is the right way to go about it. I don't think your idea's impossible, but getting it to behave like you're expecting is likely to be a lot of work in mostly unexplored territory - especially as an inexperienced machine builder - and the time, energy, and money would likely be far better spent experimenting with some scrap pieces until you get the hang of CNC'ing the cuts you need to make.

If you're going to be working on existing guitar bodies, you might also want to look into 3D digitizing probes, so you can scan the surface & make sure everything's going exactly where it should be & aligned exactly how it should (it'll also allow for fun things like engraving on curved objects), but I'm not sure what GRBL software supports it, and I hesitate to recommend going the Mach3/LinuxCNC +Gecko (or *shudder* random Chinese electronics) route for all but the most ambitious beginner.


-Bats
(Purveyor of bad ideas)

 

Great advice. I appreciate your input. I'll ditch the unpowered idea. The 3d probe sounds promising, I'll have to read up on that. Could be a great tool for copying hand carved prototypes.

 

You can directly type in line-by-line G-code or just jog- it's perfectly possible to use a CNC machine manually or semi-manually, not everything has to be fully-CAMed up. I do it all the time. For straight-line stuff that's just a few lines of code, it's the way to go. Just get used to setting arbitrary WCS zeroes wherever you happen to jog to.

And bCNC allows digitizing.

 

Good catch. I meant to mention that option too, but got a little distracted by all my less realistic suggestions.

G-code is a little intimidating at first (and a little intuitive never), but just going Point A to Point B is really quite simple (G1 X1 Y2 F40 is "go to x1, y2 at 40 [units] per minute). The one big drawback to entering code line-by-line (especially if you're using a fast fixed-speed router) is that if you're not quick enough you can end up with the tool sitting, rubbing (which reduces tool life), and potentially burning the wood - so I try to end my moves off the stock when possible.

Of course, that only works for simple shapes. A neck pocket, definitely... but the electronics on a strat would probably be better CAMed, unless you're a whole lot better than me.

I thought it might, but a quick search didn't give me anything definite.

One caveat on bCNC, though... get used to working in metric. It mostly supports inches, but I discovered the hard way that some functions are unpredictable in inch mode, or would cause it to change units without notice.


-Bats
(finder of improbable problems)

 

I just got started with my build, I must say the box of parts was a bit intimidating, I has no idea what parts where what I started with the wheels , I kept going the best I could then it dawned on me the numbers on some of the bags refer to the MM of those parts, The XL plate that laminated to the two other plates could use more detail in its orientation. I noticed the marking of the support beans with a permanent marker , Why not run some painters tape on the top and mark the tape?. Lastly In my box I see a cardboard box with a power device, in it,, what is the "Black Box packaged in? Thanks Bo

 

Hi!
How firmly should the delrin nut blocks be tightened? After putting the machine together, I have all 7 (2/X, 4/Y, 1/Z) of them somewhat loose.

Specially I can see the Y-axis nuts move at the gantry plate when I move the machine. But when I thighten them I start loosing steps.

As a reference, when I cut down power, Z axis slowly goes down with a 1,5Kw spindle, so it is kindda loose. But if I tighten them all, I should increase driver current close to its limit

Thanks!

 

Could it be that you have small steppers? They should really be NEMA 23 with maybe 260oz/inch torque

 

I have Nema 23 motors, although not the biggest ones. These have a 1.26N.m holding torque and 45mN.m detent. They have no trouble moving the spindle while powered, but unpowered they slide. Should a bigger motor slide the same way?

 

Hi I am building a lead machine and bought longer lead screws because I wanted to go 40x60. I am a guitar maker and had one part that I couldn't make on a regular 40x40. I have recently read that long lead screws can whip at longer lengths. What I am now thinking is to just add 4" to the X axis just enough to make the part needed and not much longer than the original spec.. A couple questions in the control software can I modify the size so the software knows the size of my machine? I have a shopbot but I am not that familiar with the openbuild software. Do I need a internet connection to run the control software? Thanks Greenman

 

Hello, new to this site. Started learning "Solidworks" because I can get a free version to learn. Looking to build CNC for mostly flat aluminum sheets and wood. Needs to be 60" wide. What machine is recommended? Workbee 1510? Anybody used above software with these machines? Thanks, Ed

 

My Z axis has a lead screw and not belts and it doesn't slide down at all when the machine is off.

 

Yes, they do whip but there are two things you can do to mitigate it. One is getting a thicker screw and two is to slow down the cutting speed. I use 16mm screws 1500mm long and at high speed the whip a Samba dance but I don't run them at high speed.

 

About the whipping, someone on the, ehem, Chinese workbee group on Facebook, suggested having the screws on tension, instead of in compression by putting the locking nut from the outside of the plates. Would that work? I'll try and report back soon!

 

Those do sound pretty small - if my conversions are right, those are about half the specs of the ordinary Openbuilds steppers, and Nope - I was looking at the wrong datasheet - yours are almost exactly the same as the stock model, so that shouldn't be a problem.

I'm using the high-torque model for the 1.5kW spindle on my Z axis (out of an abundance of caution - I didn't test it with the smaller ones), but the size of the motor shouldn't make much difference when they're off - steppers aren't designed to have much (or, really, any) holding torque when they're not being powered. My Z does stay up when it's off, but it doesn't take much encouragement or extra weight to send it drifting downward. The difference is presumably the tension on the anti-backlash nut (which, unfortunately, is a pain in the bats to get at once the machine is assembled).

Your Y problem is another matter, and I'm not sure quite what's going on there. If the nuts are visibly moving, it means they're introducing a lot of backlash, which is going to play hell with your accuracy & repeatability, so it's important to get that sorted. I'd go back through the assembly video (which really needs a decent table of contents, but I think it's somewhere after 1:33:00) in the bits where it shows how to tension the X & Y nuts & screws (I seem to remember it forgetting a few pieces on Z nut) and see if that does anything to address the issue. If not, hopefully it'll at least keep you distracted long enough for someone smarter than me to come up with a better answer.

Also, with regard to the missing steps, you haven't mentioned what sort of controller, drivers, or power supply you're using, which could also factor into it.

Keep in mind, he said he's using a 1.5kW spindle. If it's the 80mm version like I've got, they're awfully heavy.


-Bats
(whoever said "size doesn't matter" never tried lifting one of those beasts while leaning across the bed of a machine)

 

Thanks for your help.