CNC For A Layman

CNC - Electronics - Components - BOM listview

2008-12-06T23:23:00.000-08:00

I have reformatted the BOM ( click to see ) to demonstrate the amount of individual components needed per board.
Thus, for a 3 axis set up you would need the given quantities x 3.

CNC - Electronics - Components - PCB

2008-12-05T14:29:00.000-08:00

An order of 25 PCB for the Mardus-Kreutz Unipolar stepper drives has arrived and will be sold at cost plus shipping/handling.
Interested parties, please send an email to make arrangements.

CNC - Electronics - Components - BOM - one stop buy option

2008-12-05T14:24:00.000-08:00

This parts list was updated on 12/05/2008.
Quantities needed can be looked up in the BOM under 'CNC - Electronics - BOM'
Please use after your won verification, I have not used the list yet and will revise it another time once I have looked up all needed components one more time.

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CNC - Electronics - S R Latch

2008-11-26T20:46:00.000-08:00

Wikipedia helps us out: What is a S R Latch ?

CNC - Electronics - Mosfet and Mosfet Divers

2008-11-26T20:44:00.000-08:00

Part of the circuit are Mosfet and Mosfet drivers. A good description can be found on this website.

CNC - Electronics - SMT Naming Conventions

2008-11-20T22:00:00.001-08:00

"The electronics industry has standardized package shapes and sizes (the leading standardisation body is JEDEC). These include:

Two-terminal packages
- Rectangular passive components (mostly resistors and capacitors):
  - 01005 (0402 metric) : 0.016" × 0.008" (0.4 mm × 0.2 mm) Typical power rating for resistors 1/32 Watt
  - 0201 (0603 metric) : 0.024" × 0.012" (0.6 mm × 0.3 mm) Typical
    power rating for resistors 1/20 Watt
  - 0402 (1005 metric) : 0.04" × 0.02" (1.0 mm × 0.5 mm) Typical power rating for resistors 1/16 Watt
  - 0603 (1608 metric) : 0.063" × 0.031" (1.6 mm × 0.8 mm) Typical
    power rating for resistors 1/16 Watt
  - 0805 (2012 metric) : 0.08" × 0.05" (2.0 mm × 1.25 mm) Typical power rating for resistors 1/10 or 1/8 Watt
  - 1206 (3216 metric) : 0.126" × 0.063" (3.2 mm × 1.6 mm) Typical power rating for resistors 1/4 Watt
  - 1806 (4516 metric) : 0.177" × 0.063" (4.5 mm × 1.6 mm)
  - 1812 (4532 metric) : 0.18" × 0.12" (4.5 mm × 3.2 mm) Typical power rating for resistors 1/2 Watt
  - 2010 (5025 metric) : 0.2" × 0.1" (5.0 mm × 2.5 mm)
  - 2512 (6332 metric) : 0.25" × 0.12" (6.35 mm × 3.0 mm)
- Tantalum capacitors [1]:
  - EIA 3216-12 (Kemet S, AVX S): 3.2 mm × 1.6 mm × 1.2 mm
  - EIA 3216-18 (Kemet A, AVX A): 3.2 mm × 1.6 mm × 1.8 mm
  - EIA 3528-12 (Kemet T, AVX T): 3.5 mm × 2.8 mm × 1.2 mm
  - EIA 3528-21 (Kemet B, AVX B): 3.5 mm × 2.8 mm × 2.1 mm
  - EIA 6032-15 (Kemet U, AVX W): 6.0 mm × 3.2 mm × 1.5 mm
  - EIA 6032-28 (Kemet C, AVX C): 6.0 mm × 3.2 mm × 2.8 mm
  - EIA 7260-38 (Kemet E, AVX V): 7.2 mm × 6.0 mm × 3.8 mm
  - EIA 7343-20 (Kemet V, AVX Y): 7.3 mm × 4.3 mm × 2.0 mm
  - EIA 7343-31 (Kemet D, AVX D): 7.3 mm × 4.3 mm × 3.1 mm
  - EIA 7343-43 (Kemet X, AVX E): 7.3 mm × 4.3 mm × 4.3 mm
- SOD: Small Outline Diode
  - SOD-323: 1.7 × 1.25 × 0.95 mm
  - SOD-123: 3.68 × 1.17 × 1.60 mm
  - SOD-80C: 3.50mm × 1.50mm × More info [2]
- MELF — Metal Electrode Leadless Face — (mostly resistors and diodes): Barrel shaped components, dimensions do not match those of rectangular references for identical codes.
  - MicroMelf (MMU) Size 0102: L:2.2mm D:1.1mm (solder pad fits rectangular 0805) 1/5 Watt (0.2W) 100V
  - MiniMelf (MMA) Size 0204: L:3.6mm D:1.4mm (solder pad fits rectangular 1206) 1/4 Watt (0.25W) 200V
  - Melf (MMB) Size 0207: L:5.8mm D:2.2mm 1 Watt (1.0W) 500V
Three-terminal packages
- SOT: small-outline transistor, with three terminals
  - SOT-23: 3 mm × 1.75 mm × 1.3 mm body - three terminals for a transistor, or up to eight terminals for an integrated circuit
  - SOT-223: 6.7 mm × 3.7 mm × 1.8 mm body - four terminals, one of which is a large heat-transfer pad
- DPAK (TO-252): discrete packaging. Developed by Motorola to house higher powered devices. Comes in three- or five-terminal versions [3]
- D2PAK (TO-263) - bigger than the DPAK; basically a surface mount equivalent of the TO220 through-hole package. Comes in 3, 5, 6, 7, 8 or 9-terminal versions [4]
- D3PAK (TO-268) - even larger than D2PAK [5]
Packages with four or more terminals (drawings of most of the following packages can be found on [6])
- Dual-in-line
  - Small-outline integrated circuit (SOIC) - small-outline integrated circuit, dual-in-line, 8 or more pins, gull-wing lead form, pin
    spacing 1.27 mm
  - J-Leaded Small Outline Package (SOJ) - the same as SOIC except J-leaded
    [7]
  - TSOP - thin small-outline package, thinner than SOIC with smaller pin spacing of 0.5 mm
  - SSOP - Shrink Small-Outline Package, pin spacing of 0.635 mm or in some cases 0.8mm
  - TSSOP -
    Thin Shrink Small-Outline package.
  - QSOP - Quarter-Size Small-Outline package, with pin spacing of 0.635 mm
  - VSOP -
    Very Small Outline Package, even smaller than QSOP; 0.4, 0.5 mm or 0.65 mm pin spacing
- Quad-in-line
  - PLCC - plastic leaded chip carrier, square, J-lead, pin spacing 1.27 mm
  - QFP - Quad
    Flat Package, various sizes, with pins on all four sides
  - LQFP -
    Low-profile Quad Flat Package, 1.4 mm high, varying sized and pins on all four sides
  - PQFP -
    plastic quad flat-pack, a square with pins on all four sides, 44 or more pins
  - CQFP - ceramic quad flat-pack, similar to PQFP
  - MQFP - Metric Quad Flat Pack, a QFP package with metric pin distribution
  - TQFP - thin quad flat pack, a thinner version of PQFP
  - QFN - quad
    flat pack, no-leads, smaller footprint than leaded equivalent
  - LCC - Leadless Chip Carrier, contacts are recessed vertically to "wick-in" solder. Common in aviation electronics because of robustness to mechanical vibration.
  - MLP -
    Leadframe package with a 0.5 mm contact pitch, no leads [8]
  - PQFN - power quad flat-pack, no-leads, with exposed die-pad[s] for heatsinking
- Grid arrays
  - PGA - Pin grid array.
  - BGA - ball grid array, with a square or rectangular array of solder balls on one surface, ball spacing typically 1.27 mm
  - LGA - Same Manufacture process of BGA, has Advantage being cooler than BGA by quick Heat Deception feature. No Balls only Patch.
  - FBGA - fine pitch ball grid array, with a square or rectangular array of solder balls on one surface
  - LFBGA - low profile fine pitch ball grid array, with a square or rectangular array of solder balls on one surface, ball spacing typically 0.8 mm
  - TFBGA - thin fine pitch ball grid array, with a square or rectangular array of solder balls on one surface, ball spacing typically 0.5 mm
  - CGA - column grid array, circuit package in which the input and output points
    are high temperature solder cylinders or columns arranged in a grid pattern.
  - CCGA - ceramic column grid array, circuit package in which the input and output points are high temperature solder cylinders or columns arranged in a grid pattern. The body of the component is ceramic.
  - μBGA - micro-BGA, with ball spacing less than 1 mm
  - LLP
    - Lead Less Package, a package with metric pin distribution (0.5 mm pitch).
- Non-packaged devices (although surface mount, these devices require specific process for assembly):
  - COB - chip-on-board; a bare silicon chip, that is usually an integrated circuit, is supplied without a package (usually a lead frame overmolded with epoxy) and is attached, often with epoxy, directly to a circuit board. The chip is then wire bonded and protected from mechanical damage and contamination by an epoxy "glob-top".
  - COF - chip-on-flex; a variation of COB, where a chip is mounted directly to a flex circuit.
  - COG - chip-on-glass; a variation of COB, where a chip is mounted directly to a piece of glass - typically an LCD.

There are often subtle variations in package details from manufacturer to manufacturer"

CNC - Electronics - PCB order

2008-11-20T12:54:00.000-08:00

A few PCB boards for the Mardus Kreutz unipolar microstepper are available and can be ordered at cost. Interested parties, please send me an email.

CNC - Cost

2008-11-17T22:04:00.000-08:00

Expenses, in the order they occured:

1. Motor
VEXTA stepper motor with 10:1 inline gear ( new, value > $ 400/motor) - $ 27/motor, incl shipping; source ebay.

2. PCB
PCB ~ $ 15 per board, industrially manufactured; low price because order of 25.

CNC - Motor - Vexta PK264M-03AR12

2008-11-17T22:00:00.001-08:00

Oriental Motor U.S.A. Corp.
1001 Knox St.
Torrance, CA 90502
Tel: 800-418-7903 Fax: 800-309-7999
www.orientalmotor.com
Item # PK264M-03AR12, 2-Phase Stepping Motor
$194.00

2-Phase Stepping Motor

The High Resolution Type have half the step angle of standard stepping motors. The high resolution type increase motor resolution from 200 steps/revolution to 400 steps/revolution.

SPECIFICATIONS
Product Line                                                                              VEXTA ®
Motor Type                                                                                 2-Phase
Motor Frame Size                                                                         2.22 in. sq.
Gear/ Shaft Type                                                                        Round Shaft
Type                                                                                   High-Resolution
Connection Type                                                                        Bipolar (Series)
                                                                                                 Unipolar
Lead Wires                                                                                    6
Current per Phase (A/phase)                                                         2.1 Bipolar (Series)
                                                                                           3 Unipolar
Encoder                                                                                   Equipped
Encoder Resolution                                                                         400
Shaft                                                                                       Single
Step Angle                                                                                0.9 °
Maximum Holding Torque (lb-in)                                                      4.3 [Bipolar (Series)]
                                                                                                  3.4 [Unipolar]
Rotor Inertia (oz-in2)                                                                   0.66 oz-in2
RoHS Compliant                                                                               Yes


Insulation Resistance     100 M Ω minimum under normal temperature and humidity, when measured by a 500 VDC megger between the motor coils and casing.

Dielectric Strength         Sufficient to withstand 1.0 kV, 60 Hz applied between the motor coils and casing for 1 minute, under normal temperature and humidity.

Temperature Rise          Temperature rise of the coil measured by the Change Resistance Method is 144°F (80°C) or less (at standstill, two phases energized).

Insulation Class                                                                Class B [266°F (130°C)]
Ambient Temperature Range                                               14°F ~ 122°F (-10°C ~ 50°C)
Ambient Humidity                                                      85% or less
Shaft Runout                                                0.002 in (0.05 mm) T.I.R. at top of output shaft
Concentricity                                                0.003 in. (0.075 mm) T.I.R.
Perpendicularity                                            0.003 in. (0.075 mm) T.I.R.
Radial Play                                                   0.001 inch (0.025 mm) max. of 1.12 lb. (5 N)
Axial Play                                                     0.003 in (0.075 mm) max. of 2.2 lb. (10 N)
Step Accuracy                                                 ±3 arc minutes (±0.05°)
                                                                                               11/18/2008 | Page 2 of 2

CNC - Mechanics - Stepper Motors

2008-11-17T21:50:00.001-08:00

Today the Vexta stepper motors arrived.

The actual stepper motors that I will be using have an 10:1 inline gear, not shown on the photo.
This brings the torque to 2.5 Nm or roughly 360 on/inch.

I chose these motors because they are light and can easily be shipped, they were available and cost about 10 % of the official price, Vexta has a good name.

For a small table mill and a foam cutter this amount of torque should be enough.

Detailed specifications of the motor are listed the 'CNC motor' post.

CNC - Software

2008-11-16T21:40:00.000-08:00

The control of CNC machines is possible with the help of software.

The software that will be described here is in the open source domain.

I will discuss which components are needed and how to use those components.

CNC - Mechanics - Mineralgusstechnik

2008-11-16T21:37:00.000-08:00

Practical considerations with regards to 'Mineralgusstechnik', which is the use of a composite of minerals, a resin and a hardener.

This technique will be used to pour a frame for the CNC mill.

CNC - Electronics - Digital Signal Processing

2008-11-16T20:55:00.000-08:00

On the diagram of the translator for the Mardus Kreutz unipolar microstepper you can find a Reference Signal Processor.

Basic terms of digital signal processing, DSP, may give you a general idea of what this unit does.

A practical example of DSP.

Reference Signals in electrical motors are treated in a Labview setting and here

CNC - Electronics - BASCOM

2008-11-14T01:07:00.000-08:00

The translator that is used with the Mardus-Kreutz micro-stepper carries an ATtiny microchip. For educational reasons it has been programmed in BASCOM.

To get a good idea about BASCOM visit Ben's tutorial.

CNC - Electronics - Ordering A PCB

2008-11-12T21:17:00.000-08:00

Several websites offer production of prototype PCBs. I decided to try BatchPCB.

Their website is quite self explanatory. After a quick sign up as a new customer, you will be guided through the process to upload your Gerber and NC files.

These files are available courtesy Kreutz. You can find Kreutz by doing a search on www.cnczone.com and send a 'personal mail'.

The first attempt to upload the zip file failed - I got an error message. To follow up, I sent an email to their support. Response pending.

I expect to pay up to $ 15/PCB, including shipping. Not really cheap, but currently the best option - it would cost me more to etch it myself.

The actual quote turned out to be $ 35/PCB. Too much for a single PCB.

Anyway - how to get it to work:

- Sign in at www.batchpcb.com
- Browse to the .zip file that you want to upload to the website.
- Make sure that the .zip file does not contain any sub-folders.
- the website will guide you to select the correct files from your .zip folder
- check that your NC file is correct
- email responses for support are immediately returned from BatchPCB; impressive.
- at the end you get a quote/PCB based on the sq inch size of your designed board.

Overall a relatively pain free process - work through it once and you are set.

CNC - Electronics - Basic Reading

2008-11-12T16:58:00.000-08:00

A good source for basic reading can be found at Sparkfun Electronics; a tutorial on PCB design in their projects section.
Overall 78 tutorials cover many different topics - soldering, embedded design and more.

CNC - Electronics - Unipolar Microstepper

2008-11-12T14:46:00.000-08:00

For this project the unipolar micro stepper drive for stepper motors has been selected. Details about the drive and it's assembly can be found on the Mardus-Kreutz blogsite.

CNC - Electronics - Components - BOM - Mardus-Kreutz Driver

2008-11-12T14:26:00.000-08:00

Two PCB need to be assembled:

- the motor diver
- a translator card

Bill of Materials for the Mardus-Kreutz unipolar stepper motor driver PCB.

The bill of materials for the translator card will be added when available.

Alternatively, a 4 axis interface card that will incorporate the translator function is available from Kreutz.

CNC - Electronics - PCB Naming Convention

2008-11-12T14:09:00.000-08:00

To be able to collect the parts needed it is necessary to understand the PCB naming convention. The linked document explains the convention in detail:

PCB Naming Convention

Read through this document and you will understand the 'footprint' of a listed part.

General Purpose of this Blog

2008-11-11T14:38:00.000-08:00

The general purpose of this blog is to trace the development of a CNC system from a layman's perspective.

A tutorial.

This blog will initially follow the assembly and set up of the electronics required.

In a second phase the reqiured software will be discussed briefly.

In a third phase the custom assembly of the mechanical part will be chronicled.