[Andrewsp]

Hello everyone, my name is Andrew, I'm from Portugal, and I'm new to this world of CNC machines, so pardon me if I come up annoying you guys with all my questions, which I have a lot btw!
So, I'm actually thinking of making my first cnc machine, and since I don't know anything about it, I was hoping that you could help me with it!
Okay now, I think I might go for a 3 axis, 1meter x 1meter table, and that's pretty much what I can decide so far, since I don't know what type of motors I'll have to use, what type of board, bearings, drivers, etc...
Once again, I'm sorry to bother you with this, I'm sure that you've all done and answered this endless times before, but I really am noob at this, and I really could use your help here!
Thanks in advance,

Andrew S.

[hub]

- What material(s) will you be cutting?
- What is you budget?
- How much precision do you need?

[Andrewsp]

Before anything thanks for answering!
I'll be cutting wood and plastics mainly... Can i keep it under 200 euros, without counting with the table frame? How much precise can it be?

[plcamp]

Before anything thanks for answering!
I'll be cutting wood and plastics mainly... Can i keep it under 200 euros, without counting with the table frame? How much precise can it be?

Your working area is very important when determining any projected cost, how big are your work requirements? Also what construction method are you targeting, a machine fabricated from aluminium extrusions versus wood construction commands a sizable increase in your building budget?

[rlwoodjr]

I think it would be difficult to build a machine for under 200 euros unless you have sources for used parts. What parts do you have available?

[Andrewsp]

Your working area is very important when determining any projected cost, how big are your work requirements? Also what construction method are you targeting, a machine fabricated from aluminium extrusions versus wood construction commands a sizable increase in your building budget?

Tanks for answering plcamp! I would use it to work on guitar bodies, as well as necks, inlays and so on. Could I make the working area smaller? At this point I'm still deciding if I should make it out of aluminium or MDF. As far as the budget, since the building process will take sometime, I imagine, the budget will grow at some point, but keeping in mind that this is a DIY project.

[Andrewsp]

I think it would be difficult to build a machine for under 200 euros unless you have sources for used parts. What parts do you have available?

Thank you for the reply rlwoodjr! If you don't mind, I've been looking at some parts from a website in my country, and fortunately it is in English, so if you could take a look at this link and give me your feedback I would appreciate it! Here it goes: Leds & Chips
They have a CNC section in there, but from what I've saw, the cnc shield is for a 4 axis am I wrong?

[hub]

Andrewsp,
200€ is not enough. Maybe for some sort of MDF design with a low end router as a spindle. Then round rods with plain bushings. And as screws & nuts acme rods.
+ fasteners etc etc etc. Maybe could be done for under 200 without motors & drivers..
It won't be very precise, depends on what components are used. And expect to use slow feed, slow RPM ans shallow depth of cuts with a 'flimsy' machine.

[Andrewsp]

Andrewsp,
200€ is not enough. Maybe for some sort of MDF design with a low end router as a spindle. Then round rods with plain bushings. And as screws & nuts acme rods.
+ fasteners etc etc etc. Maybe could be done for under 200 without motors & drivers..
It won't be very precise, depends on what components are used. And expect to use slow feed, slow RPM ans shallow depth of cuts with a 'flimsy' machine.

Okay, so putting aside the 200 euros budget, that obviously wont get me the kind of machine that I need for the sort of work that I want to do, what would you recommend me to do? What kind of mechanics should I choose so I could work on wood to make guitar bodies and so on? I've been looking around at youtube and I've seen some people using MDF made machines to make guitars, but since I would like to end up with a reliable machine, one that I could count on to do the job neatly! Here's a link of a frame that got my attention (https://www.youtube.com/watch?v=3SZsm8Sl0Ao) I like the way it looks and the way it runs soomthly I suppose, what would be the budget on the mechanic parts on one of these? Once more thanks for everything!

[Andrewsp]

So since my lack of understanding on this matter is quite big, I've come up with a question list on where my confusion relies, so I could hopefully make it easy on all of us! Referring to the last post where I left a link of a machine that got my attention, I'll go ahead and try to leave my questions, and once more I'm sorry for my ignorance when it comes to this matter!

What kind of system does this machine have to move around?

What kind of motors would I need to run fast and support the weight of the bridge?

How would I connect the motors to the "bars" (yet to know the technical term) where the moving parts should sit?

Can I use a Arduino CNC Shield ( CNC Shield for Arduino (GRBL Compatible) ) for this machine?

What kind of spindle should I use?

And also, what's missing here?

[ger21]

Here's the info for the machine in the video. He sells a kit without the steel tubing for $5000.
XYZ-CNC

It uses rack and pinion, and it says linear bearings, but doesn't actually show them, so I'm a little confused.

Arduinos, and GRBL are usually used on small hobby machines, as they typically tend to work with small motors. But I don't know much about them.

What kind of mechanics should I choose so I could work on wood to make guitar bodies and so on?

I don't know how much your willing to spend, or what kind of performance your expecting, so it's impossible to answer that.

Yes, you can cut guitars on a $1000 machine made of MDF and skate bearings. But are you capable of building it so that you'd want to?

[ger21]

Actually, it looks like the kit is an updated version of the machine in that video.
Here's a video of the machine in the kit.
It looks to me like the machine is using skate bearings (or similar) riding on the steel tubing.

[louieatienza]

Andrew, it's a lot harder now to find surplus linear rails on eBay, at a good price. The Chinese SBR rails on eBay would be a decent choice for an inexpensive wood router. I bought some profile linear rails and bearings from a Chinese supplier and will wait till receipt before I give my impression and review.

They make Arduino stepper drive shields that can handle 40v and 3.5A, which should be enough for a larger table. GRBL as I understand does trajectory planning, but there's no set GUI, and I think there's still room for development. There is a guy in the Benchtop Machines forum working on this right now and it looks good so far."

I build guitars both electric and acoustic, and my table is 32" x 28" which is plenty. I suggest about 6" z axis clearance. Multiple start screws with AB nuts is probably the easiest and least expensive way to drive your table.

[rlwoodjr]

Thank you for the reply rlwoodjr! If you don't mind, I've been looking at some parts from a website in my country, and fortunately it is in English, so if you could take a look at this link and give me your feedback I would appreciate it! Here it goes: Leds & Chips
They have a CNC section in there, but from what I've saw, the cnc shield is for a 4 axis am I wrong?

This is a 4 axis board and would work a 3 axis machine. The board is made for the Arduino. I have used this shield with DRV8825 stepper drivers without the Arduino connected to a LinuxCNC machine on the router I am working on at BobsCNC

[hub]

Okay, so putting aside the 200 euros budget, that obviously wont get me the kind of machine that I need for the sort of work that I want to do, what would you recommend me to do? What kind of mechanics should I choose so I could work on wood to make guitar bodies and so on? I've been looking around at youtube and I've seen some people using MDF made machines to make guitars, but since I would like to end up with a reliable machine, one that I could count on to do the job neatly! Here's a link of a frame that got my attention (https://www.youtube.com/watch?v=3SZsm8Sl0Ao) I like the way it looks and the way it runs soomthly I suppose, what would be the budget on the mechanic parts on one of these? Once more thanks for everything!

MDF is not that bad actually, if thick enough. I would paint it though so that moisture won't affect it.
You'd want:
- good linear shafts & bearings (here are some pro versions: Profiled Rail Systems - Bosch Rexroth AG)
- good screws & nuts (pro here: Profiled Rail Systems - Bosch Rexroth AG)
(of course those pro ones will cost a lot..)

I used for linears fixed steel shafts with open type linear bearings. Not the best but that's what I had in my budget...
For screws I have economical C5 grade 16x5mm rolled ball screws & ball nuts. Again, that was my max budget...
I was lucky to get some servos + drives, so I replaced my steppers with them. (Still have 3 extra steppers & drives, will have to figure out where to use them...)

I think a good(ish) performance for as low a cost as possible would be big enough steel shafts (fixed in each end) with sliding bushings, there are some nylon (or similar can't remember) that are pretty good I've heard. Not tried myself though.
Get ball screw & nuts if the budget allows. If not, use acme. A random search, something like this: Trapezoidal Rolled Lead Screw Precision range. Moore-international.co.uk.
I would choose a higher pitch, 8mm+, if you use steppers. You probably want some speed. (I originally chose 5mm pitch screws, didn't work well with my steppers.. with servos it's fine though in my case)

There are lots of people running their spindle/router at 25.000RPM and cutting slow at 100-200mm/min or something. It will just burn the wood and the router bit won't like it either..

Design/plan all that (mechanics) first. Then decide on what controller, motors, electronics you need.

Hub