Let's Make Robots!

Its a project in the making ! A small scale CNC router. i want to be able to rout PCBs with it, but time will tell if it will be good enough to rout PCBs. the mediator between the PC and the motor controllers will be an arduino.

here are some pics for now ! Sorry for not writing a lot of info ! a picture is worth a thousand words :P

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TheTrustedOne's picture

Steppers dont miss steps they try to accomplish everyone however,

 

an object at rest tends to remain at rest unlesss acted upon by an outside force, and an object in motion tends to remain in motion unless acted upon by an outside force.

 

basically if the matrial provides to much resistance and the rubber band streches or the head cant move because the stepper isnt powerfull enough it can miss a step that way.

 

Chris the Carpenter's picture

Yup, I just got it... That's funny --I'll give you points for that.

JAX's picture

The biochemist in me was like, "Silicon and silicon bot? Hmmm... Oh yeah..." You think living by the US-Mexico border it would have been instant.

TinHead's picture

The "Si-n-Si" is a nice fun project, I thought I should give you a few pointers to start:

The hardest part is the mechanics, and it is best to design it as sturdy as possible from the beginning. Dump the printer head carriage it will not do for a milling machine, it is designed to simply move the head around without encountering any force, trust me it will fail miserably from my experience - use a screw to drive the axis it works very well even with normal screws, I use M8 but you could use M6.

The mechanics should employ some sort of linear bearings to make sure the axes are only allowed to move in one direction, having play in any other direction is very bad, you need to avoid that.

The motors seem similar to the ones I have started with, I'm guessing they are 48 full steps per turn, should be fine for a start.

Not sure about the drivers, you seem to be using l293 or similar,  and you are using a transistor to spare some pins, I think. They should work for a start but I suspect you will soon have a second version of them ;)

Have fun!

Geir Andersen's picture

What I am wondering about is, have anyone seen a home made CNC machine based on a prebuilt XY table?
http://littlemachineshop.com/products/product_view.php?ProductID=2008 and interfaced it with steppers? 

You still have to figure out a Z-axis but still you will start of with a rock solide XY table and for PCB work that might be just the thing.

 

birdmun's picture

I have not seen any DIY machines based on prebuilt tables, but, I have seen a number of machines built as converted manual 3 axis mills. Typically one of the complaints is about the tolerance of the lead screws that some of the affordable mills use. As for the prebuilt tables, you could readily use one and having a stationary z axis would be fairly easy to construct. The only issue I would have with the table you found would be the limited travel available.

Jad-Berro's picture

Well in fact, i do feel that the printer head setup is really sturdy ! i will put some tension on the rubber track so it becomes stiffer. and with the gearing that i placed it is truly unstoppable. I will use a center screw to drive the gantry back and forth . I will use a screw to drive the spindle up and down as well It will be a sturdy design made from solid MDF. i will do frequent updates and would always love to read your comments :) i have seen your CNC and it's truly amazing :)

I have a question for you ! i liked the EMC^2 software that you are using but what electronics should i have to interface to it ?! can it be done with an arduino ?!

birdmun's picture

EMC by default comes as an iso that uses Ubuntu LTS release as the OS. Grab the iso and run it from the cd to get a feel for it. It can be run as a LiveCD as other versions of *Ubuntu.

Like TinHead said, you won't need the arduino as EMC can output step and direction pulses directly to your board. You will need to make sure the system you intend to use will work though as some systems have insurmountable issues generating pulses in a regular manner.

TinHead's picture

... and thank you!

Sturdy definition: As long as you can move a part of the machine in directions it is not supposed to go, it is not sturdy enough or something has got really wrong somewhere :)

You may try with the printer carriage, but I seriously doubt you'll be able to get any precision out of it. I started the same way, did the basic testing after which I have built the Beast .... looong looong time ago. 

I'm still not happy with sturdiness on my machine ... but it is improving.

EMC2 uses the parallel port to send pulses to the drivers, so if you use it you do not need the Arduino. 

 

rik's picture

Tinhead is warning you for precision issues. Never mind if the setup is strong enough. Tinhead's point is: you will have many errors in the end product unless you make you mechanics very sturdy or stiff. Less play means more precision in the tracks you can create on you PCB. How narrow will your traces be?

Stiffer = better (NISM?)