Wednesday, June 19, 2013

GRBL Arduino Connector Shield

This shield plugs into a standard Arduino, such as the Uno with the Arduino pins connected to a 26 pin IDE dual inline socket. A ribbon cable with a 26 pin IDE on one end and a DB 25 pin IDE on the other can be used to connect the shield to a typical breakout board. The pinout is chosen to match the SainSmart ST-V6 breakout though it may match others. The DB pins for the X,Y,Z and A are pretty standard. The Enable is normally on pin 1, but some have it on 14.

The schematic shown below includes a complete pinout for the DB, IDE and Arduino. The schematic was done with the free schematic capture program, TinyCad.
Arduino GRBL Connector shield schematic using TinyCad
In this blog we will include a breakout of our own design with connectors instead of terminal blocks and a driver board using Pololu type driver plugins. Both will use the 25 pin DB male connector even though many USA made breakout designs use a female connector.

Monday, June 17, 2013

SainSmart ST330 V2 TB6560 Stepper Driver

This SainSmart stepper driver uses the TB6560 driver chip good to 3.5A and 34VDC. As with many SainSmart boards there is no schematic but there is a chinglish manual. This driver is available from Amazon with fast deliver for $18 ea.

Top of ST330

Bottom of ST330

The first order of business was to create a schematic which, as expected, reveled an interesting feature which is not mentioned in the manual.

Schematic for ST330. Done with TinyCad
The step signal sets the74HC123 retriggerable one shot. The one shot stays in its set mode as long as there are step pulses. One output of the one shot lights the run led and the other controls the motor run and idle torque. If the torque switches are left open then at run the torque is at 100% and at idle is 50%.

Overview of CNC Router Project

Project purpose: To build an inexpensive CNC router for the Making Awesome makerspace for teaching and general use.

The Mechanism: The mechanism was to use the ShapeOko basic design, but to be built with on hand and donated parts where possible.

The Electronics: Because this is a teaching machine we set the following criteria.

1) The electronic should be inexpensive and serviceable.

2) The initial system will use LinuxCNC software and, therefore, require a parallel port desktop.

3) A later system will use an Arduino with GRBL and require some PCB development. See post.

Selected Electronic Hardware:

1) SainSmart 5 Axis breakout board ST-V6 at $23.

2) SainSmart TB6560 driver board ST330 V2. Only one was purchase at $18. See blog post.

3) Haoyu TB6600 driver. Two purchased at $20ea

4) Power supply: 24VDC at 6.5A

5 Axis Breakout Board, SainSmart ST-V6

This breakout board seems to be sold under several name, SainSmart being one of them. As with all the SainSmart boards there is no schematic and also in this case no manual. The board does appear to be well made.
Breakout Top View

Breakout Bottom View
 The board has been traced and a schematic is shown below. Also a pinout for the DB25 is shown.

Pinout for SainSmart 5 Axis Breakout

Pin Signal Name
1 Enable
2 X-Step
3 X-Direction
4 Y-Step
5 Y-Direction
6 Z-Step
7 Z-Direction
8 A-Step
9 A-Direction
10 IN1
11 IN2
12 IN3
13 IN4
14 Spindle Relay
15 IN5
16 B-Step
17 B-Direction
18-25 Grd

Friday, June 14, 2013

CNC Router Mechanism

At the Making Awesome makerspace we are building a small CNC router from parts we and friends have on hand. You could say it is a CNC router built from found parts. Here is a picture of the mechanism as of today.
CNC Router of Found Parts
Our makerspace does not have metal working equipment which is handy for making parts though we do have 3D printers. Lucky for us the member making the CNC mechanism has a shop of his own which includes lathes, mills and home grown CNC equipment.

The X-Axis and the Y-Axis, gantry use V grooved bearings on V shaped extrusions. The gantry will be moved by a single NEMA 23 step motor using a 3/8-12 threaded rod with X and Y using NEMA 17 and 1/4-20 rod.

More pictures to follow.