Mechanical Issues For A Pi CNC

The Raspberry Pi platform has become popular in the maker community for various CNC projects. The single board computers are readily suited to acting as a server for a small CNC setup or 3D printer, though it’s fair to say that for heavy work they probably aren’t quite up to the task of driving the steppers in a serious rig directly. [Danny] set out to try to build a CNC plotter of his own, using a Pi Zero, and learned a few things along the way.

The plotter uses 3D printed parts combined with brushed DC motors which are geared down. Potentiometers are added to allow the Pi to keep track of the location of the pen. This enables the position to be corrected through feedback.

While the plotter does move and accept commands, it does have some issues. There is significant play in the gear train which [Danny] suspects of causing the poor output results. If you’ve got any ideas as to how this could be improved or overcome, throw them down in the comments!

We’ve seen another take on CNC control with the Raspberry Pi, too. Video after the break.

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We Couldn’t Resist This CNC Batik Bot

Batik is an ancient form of dyeing textiles in which hot wax is applied to a piece of cloth in some design. When the cloth is submerged in a dye bath, the parts covered with wax resist the pigment. After dyeing, the wax is either boiled or scraped away to reveal the design.

[Eugenia Morpurgo] has created a portable, open-source batik bot that rolls along the floor and draws with wax, CNC-style, on a potentially infinite expanse of cloth. The hardware should be familiar: an Arduino Mega and a RAMPS 1.4 board driving NEMA 17 steppers up and down extruded aluminium.

Traditionally, batik wax is applied with a canting, a pen-like object that holds a small amount of hot wax and distributes it through a small opening. The batik bot’s pen combines parts from an electric canting tool with the thermistor, heater block, and heater cartridge from an E3D V6 hot end. [Eugenia] built the Z-axis from scrap and re-used the mechanical endstops from an old plotter. Check out the GitHub for step-by-step instructions with a ton of clear pictures and the project’s site for even more pictures and information. Oh, and don’t resist the chance to see it in action after the break.

We love a good art bot around here, even if the work disappears with the tide.

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The TinyG Motion Controller

When you go to a trade show of any kind, you’re expecting cool demos in the booths. At Maker Faire, there were plenty, but one of the most hypnotic was a robot built around Synthetos’ TinyG motion controller.

The demo was simply a large CNC gantry moving a ball bearing around on a string. The gantry moved in the X and Y axes, and the miniature wrecking ball was spooled and unspooled in the Z axis. The ball move around the space, coming to a complete stop without any swaying. There were even a few clear plastic tubes that the ball fell in, and popped out of without raising or lowering the string. It’s the height of motion controller coolness, all made possible with the TinyG.

The TinyG was one of a few motion control and CNC boards found at the faire. In its base configuration, it has 6 axes of motion control, RS485 to network several boards for crazy machine configurations, and a suitably powerful processor to do everything correctly.

BeagleBone Black + RAMPS

CRAMPS

The BeagleBone Black, with an impressive amount of computing power and a whole bunch of I/O, would make an impressive CNC controller, save for two shortcomings: The BBB isn’t in stock anywhere, and CNC capes are a little on the pricey side. [Marc Peltier] can’t do anything about finding a distributor that doesn’t have the BeagleBone on backorder for you, but he did come up with an adapter for the very popular RAMPS-FD 3D printer controller board (Forum, French, Here’s the Google translation matrix).

The RAMPS-FD is an extension of the RAMPS board and a shield for the Arduino Due. Both the Due and BBB work on 3.3 V, meaning controlling the RAMPS-FD is simply a matter of finding the correct wiring diagram and pin assignments on the BeagleBone. [Marc] solved this problem by using the settings from the BeBoPr cape and using the existing BeBoPr LinuxCNC configuration.

The end result of [Marc]’s tinkering is something a lot like [Charles Steinkueler]’s CNC capes for the BeagleBone Black we saw at the Midwest RepRap Fest. [Charles] isn’t selling his capes, but no one else seems to be selling BeagleBone Blacks, either.

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A Brilliant And Elegant CNC Pendant

pendant

[Mike Douglas] has a small hobby CNC router, which works great — but you’re limited to controlling it from your PC. And unfortunately, there just aren’t pendants made for this consumer level stuff. Annoyed at having to reach over to use his keyboard all the time, he stumbled upon a simple, but brilliant solution: A dedicated USB 10-key pendant keypad.

These USB keypads are designed for laptops that don’t have full size keyboards. They can be had for a few dollars from China, and let you expand your keyboard possibilities… All [Mike] had to do was print off some stickers to put on the keys!

It’s easy to program new hot keys in Mach3  — and there you go! Why haven’t we thought of this before? While you’re at it, why not build a cyclonic dust separator for your CNC too — and if you’re having trouble clamping down work pieces, [Mike] has a pretty cool solution for that as well.

 

 

DAGU: The Standalone CNC Controller

CNC

In terms of user interfaces, 3D printers are far, far beyond the usual CNC machine. It’s difficult to find a new, commercial 3D printer without some sort of display, set of buttons, and an SD card slot for loading G Code and running a printer. For CNC routers, though, you’re usually dealing with a parallel port interface connected to an old computer.

DAGU hopes to change that by providing a huge 240×128 LCD display, a bunch of buttons, and an SD card slot for loading G Code directly from an SD card. This is a fully functional controller, able to deliver 3.5 A to each stepper motor winding.

Right now DAGU is in the prototype stage, but already there are some really interesting features: the interface allows for a basic preview of the job before it begins, and should be somewhat affordable. At least as cheap as using an old computer for CNC control, anyway.

Video demo of the use and operation of DAGU below.

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