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Machine Design on DIY Manufacturing

Machine Design has an article on Do It Yourself Manufacturing, basically talking about small (often 1 person) niche companies doing design with CoCreate PE or Alibre Design and manufacturing using personal CNC tools from Tormach.

September 3, 2010   No Comments

Mechanical CAD, Special Deals, and Me

When I look at my traffic stats, I see there’s a lot of interest in affordable mechanical CAD.  I think that interest is good: I do not believe in pirating software, and I believe there is a place for affordable MCAD (and affordable CAM for desktop CNC machines), especially for personal use and as a tool for people who aren’t primarily mechanical designers.

I own licenses of Alibre Design Standard V11 (which I bought during the $99 sale) and VX Innovator V14 (which I bought on sale for $195).  I also have free licenses for DoubleCAD XT and CoCreate PE.

I mainly plan on using Alibre and VX Innovator, and reporting my experiences here.  They are somewhat complimentary; Alibre is a pretty standard history-based parametric modeler (with some nice features such as Acrobat 3D output), and VX is a hybrid modeler (solid and surface).

DoubleCAD looks very capable for 2D CAD, but I don’t expect to use it a lot.  I mainly use it for viewing and experimenting with DXF files created by Eagle PCB.

I do like CoCreate PE, but don’t plan on using it much now that I have Alibre Design and VX Innovator.  It’s limited to 60 parts per assembly, which I could easily exceed when modeling a PCB, and cannot export STEP files.  PTC has offered some very big discounts in the past to upgrade to the full version, but the annual maintenance  cost is way too high for my budget.

However, this is not a MCAD blog; my interest in still primarily in automation software and system integration (including PCBs).  OK, I do plan on writing more, but mostly I want to write about my experiences with affordable MCAD.  I do not have the time or interest to keep up with all the latest deals.  But I still might mention deals or MCAD news occasionally.

If you want to keep up on the latest special offers, you should visit MCAD sites such as and World CAD Access.  Also, if you register for the free versions (e.g. Alibre Design Xpress, CoCreate PE, DoubleCAD XT) you will receive e-mail offers.

Alibre has had a lot of good deals (maybe too many).  I’m currently sticking with V11 because I haven’t used it enough, and the improvements in V12 aren’t compelling for my uses.

VX had another sale on VX Innovator around Christmas, but they aren’t as good at marketing as Alibre; if you’re interested in a deal on VX, you should check their web store frequently.

Kubotek has had some sales, too, such as Kubotek Spectrum for $99; current deals include $700 off KeyCreator.

My latest MCAD news is here.

January 14, 2010   3 Comments

Alibre Design Xpress 11 won’t import STEP files

Alibre continues to restrict Alibre Design Xpress’ functionality; in Xpress 11 after the 30 day evaluation runs out, you can only import AutoCAD (DWG, DXF) files, and export STL files.

I’ve used Xpress occasionally since it was introduced in 2005, and I’ve never had problems importing STEP  (or IGES) files until recently.  Since I mainly use mechanical CAD to model PCBs populated with manufacturer provided part models (typically in STEP or IGES formats), this means Xpress is no longer useful.  As far as I’m concerned, Xpress is now basically just a trial version — great if you want to evaluate Alibre Design before buying, but not useful on its own.

Since I’m not making any money from the PCBs, my budget for MCAD software is basically $0 (OK, I might go up to $250 for software that did a really great job).  If I were primarily doing mechanical design, especially for money, then my budget would be different.

I’m still thinking about what I want to do; my default option is to model in CoCreate PE, which only exports STL and VRML files, but at least it imports DWG, DXF, STP, and IGES files, so it’s still easy to model PCBs in CoCreate and check that all the pieces fit together.

Go here for my latest MCAD news posts.

August 7, 2009   5 Comments

CoCreate PE Tip: Fix for Intel X3100 Problems

I was having weird problems trying to run CoCreate PE on my Thinkpad: sometimes CoCreate would complain that the display resolution had changed, the model would disappear all the time (just from moving the mouse around), and such.

My Thinkpad has an Intel GMA X3100 integrated graphics chip (also known as the Mobile Intel 965 Express Chipset).  It’s not the greatest mobile chipset, but I was more interested in a small laptop with long battery life, and the laptops with mobile Quadros (e.g. Lenovo W700) are large, heavy, and have short (OK, normal) battery life.

Anyway, I found a tip via the CoCreate Users forum: turn off hardware graphics acceleration by setting the SDPIXELFORMAT environment variable to SOFTWARE; detailed instructions are here.  So far after making this change, CoCreate has been stable, and speed is still fine.

July 1, 2009   1 Comment

FP-SMC-1 PCB Layout Is Done

3D Model Top View

3D Model Top View

It’s designed!  After taking way too much time, I have finally finished the layout for my FP-SMC-1 board.  Here’s the proof: above is a 3-D model of the board; below are pictures of the layout and the board model from the bottom.

PCB Layout

PCB Layout

PCB Bottom View

PCB Bottom View

The board hasn’t been built yet, because I wanted to model it first, and I haven’t found a good place to get one-off prototype PCBs made.

Creating the board model was challenging, but worth it, because it gives me more confidence that my board layout is correct.  I use the 3-D model to check:

  1. That my PCB footprints are correct.  Look at the picture of the board bottom, and notice how all the pins line up with the holes.  (This check relies on correct 3-D models from the manufacturer.  If you create 3-D models yourself, it’s possible for you to make a mistake in the model, but the manufacturer’s models should be correct).
  2. That my board dimensions are correct and the PCB will fit into the holder.
  3. That my component layout makes sense.  Look at the far left of the board top view picture, and notice that there is clearance between the connectors and the little plastic tabs on the PCB holder that stick out into the board area.

I will go over making the model in detail later, but what I did was roughly:

  1. In Eagle PCB board layout, turn on only the dimension, via, and pad layers (layers 17, 18, and 20)
  2. In Eagle PCB board layout, use a ULP to create DXF of the pads, vias, and dimensions.
    1. Eagle includes DXF.ULP to create DXFs.  However, this file does not produce DXFs that can be used to extrude a through-hole board.  To get DXFs that CoCreate can extrude, I had to modify DXF.ULP and then delete and re-create the board outline using DoubleCAD.
  3. Import the DXF file into CoCreate and extrude it to 0.062″.
  4. Import models of all the components (fortuneately, all the parts have STEP models available from the manufacturer).
  5. Assemble (using mates) all the components onto the PCB
  6. Assemble the PCB holder
  7. Mate the PCB to the PCB holder.

It sounds so easy, but mechanical CAD software has a high learning curve, just like PCB software.  However, if you’re a software guy, don’t be scared — I’m primarily a software guy, and if I can figure out how to make a PCB and then model it, then you can too.

I was originally planning on doing a series of blog posts on the FP-SMC-1 PCB covering just the automation-related aspects of the project, and not covering the details of using the tools (such as Eagle PCB).  However, after I looked at various Eagle PCB tutorials, I decided that none of them explained Eagle the way I think it should be explained.  I did not find any tutorials on making mechanical 3-D models.

So I have decided to write up a lengthy tutorial on how to design and make the FP-SMC-1 board.  The tutorial will be on my Trac site, since I think Trac is better suited for a lengthy tutorial, but I will blog here about my progess (hint: don’t expect the tutorial to be done quickly).

March 18, 2009   3 Comments

Viewing STEP files

Why am I interested in viewing and measuring STEP files?  Because I can make a better automation PCB if I can use STEP files.  Mechanical engineers, of course, like 3D models they can import and use in assemblies, but I am mainly concerned with PCBs.

There are a variety of standard 3D file formats, including IGES, STEP, 3D PDF, STL, VRML, ACIS, and 3D PDFs.  The most common formats for electrical components are IGES, STEP, and, recently, 3D PDFs.  My experience is that STEP files typically import with fewer problems than IGES; 3D PDFs are very nice for viewing parts, but unless the file creator took the proper steps, cannot be used for measuring.

My uses for STEP files include:

  • Viewing parts.  I can’t synthesize 3D parts in my head from a set of 2D drawings, and sometimes it’s very useful to see what a part looks like.   I really like to have real parts to play with, but that’s not always possible.
  • Sometimes the manufacturer’s 2D prints do not give all the information I want to create my PCB component shape.  I can get any dimension I want from a STEP file.
  • It’s very easy to screw up PCB connectors.  Doing a quick assembly of the PCB and components lets me verify that my drill sizes are correct, check for cable orientation, and such.

Since I am not doing any heavy duty mechanical design work, I did a bit of research into free MCAD programs that can view and measure STEP files, and preferably create small assemblies.  I found one program specifically designed as a STEP file viewer, IDA-STEP.   The free version of IDA-STEP does not measure.

However, most free MCAD programs can import and then measure STEP files.  I took a quick look at five different programs, listed below.  CoCreate PE is my favorite of the bunch; it seems the best match for a non-mechanical guy like me.

  1. CoCreate PE
  2. PowerSHAPE-e
  3. Alibre Design Xpress Note: since Alibre has dropped STEP import from Design Xpress, it is no longer a good choice.
  5. Acrobat 3D PDF
  6. CAD Exchanger (a program to convert between CAD file formats, but it also works as a viewer)
  7. CADFaster|QuickStep is another CAD file viewer with free and paid versions; when I get time, I will give it a short test.

Note that the free versions of MCAD programs exist primarily for marketing reasons, and the terms can (and have) changed at any time.

There are other free Mechanical CAD programs that might be able to read STEP files, including:

January 26, 2009   11 Comments

Viewing STEP files with CoCreate Personal Edition

Note 3/15/2012: CoCreate PE has been replaced by Creo Elements/Direct Modeling Express. I haven’t tried it yet.

CoCreate Personal Edition is the free version of the CoCreate CAD program.  CoCreate PE requires an Internet connection every 3 days, can import IGES, STEP, DWG, and DXF files, export STL and VRML files, and is limited to a maximum of 60 unique parts per assembly.

You can drag and drop STEP files onto CoCreate.  It has a pretty complete set of pre-defined views.  Performance on my system is snappy.  I found measuring easy.  Hmm, so far pretty short and sweet – that’s because I like it.  It’s my favorite of the four programs I’ve tried (CoCreate, Alibre, PowerSHAPE, IDA STEP) – it seems the most intuitive to me, and was definitely the easiest to use to measure parts.

Note that like all other free CAD programs, the terms may change in the future.  For example, PTC (the current owner of CoCreate) had a free CAD program called Pro/Desktop that was later dropped (IIRC, the current users were given a five year license).

Measuring HD26M with CoCreate

Measuring HD26M with CoCreate

January 20, 2009   1 Comment