The posts include a number of simulations which are helpful in understanding the different control topologies.  However, there is still no substitute for spinning actual motors.

Commercial controllers are great at getting you up and running quickly, but don’t let you play with different control techniques.  For learning, motion control development kits are the way to go.

My dev kit is TI’s DRV8312-C2 kit with a F28035 DSP, DRV8312 brushless DC driver chip, and servo motor (unfortunately TI didn’t include a dual shaft model, but I have plenty of servo motors with encoders).  TI’s ControlSuite software provides a variety of control methods.

• Siemens PLM Systems is making the student edition of Solid Edge available to basically anyone for free.  Limitations include no commercial use, files incompatible with commercial Solid Edge, and watermarked drawings.  See Deelip’s post for more details.
• ASCON has introduced Kompas 3D-Home for $50.  David Levin says that Kompas 3D-Home cannot be used commercially, but otherwise has no limitations.

The “Big 4″ have been up to a lot:

• SolidWorks is being brought closer to its parent (Dassault Systèmes).  It’s highly probably that a new version based on the CATIA V6 CGM kernel is coming, possibly cloud based.
• PTC has put Pro/E out to pasture, and is busy trying to get its new Creo components out.  Creo is supposedly to be modular (including history based and direct modelling modules) and app-oriented.  The vision sounds nice, but I suspect that the actual operational and pricing details will make it evolutionary, not revolutionary.
• AutoDesk is adding direct modelling to Inventor via the Fusion program.  The free 123D program is a cut-down, stand-alone version of Inventor fusion.  123D looks quite useful, but I expect it’ll be neutered if it starts to impact Inventor revenues.
• Siemens PLM Systems is finally getting its Solid Edge act together.  They’re concentrating on making Solid Edge the best program for machine design, and Synchronous Technology V3 (direct and history based modelling) has been getting good reviews.

There’s been even more change with many of the smaller players:

• 3D Systems recently bought Alibre.  A few months ago Alibre introduced a $1500 bundle consisting of a RapMan 3D printer, Alibre Design Personal, and MoI.  I’ll be interested to see what happens next.

• The $97 Alibre Design Standard deal really was a great deal, just for the translators and 3D PDF output alone, but the recent pricing and capability changes (e.g. removing almost all import and export options from AD Personal) really neutered the entry level version.
• I’m hopeful that 3DS will provide resources so Alibre can keep improving (especially since I just paid for Alibre maintenance!)

• On the positive side, ZWCAD is trying to treat customers well, there have been no US layoffs as far as I know, they have been investing money into ZW3D (licensing more components, adding more developers, etc), appear to be listening, and probably have a good upgrade policy.
• On the other hand, it’s taking a  (long?) while for them to get up to speed, they’re going to a reseller-only approach (e.g. you have to contact your reseller to upgrade), and they really need to spend some money and hire some good US marketing folks.
• For example, when ZWCAD took over, they gave all customers a free upgrade to the next level.  So if you had VX Innovate, you got upgraded to ZW3D 2010 Standard, if you had VX standard, you were upgraded to ZW3D 2010 Professional.  I think this was a great gesture, but ZWCAD never received any publicity for this.

I plan on discussing my experiences with Alibre, ZW3D, and 123D, but I won’t make any promises on how often I’ll have time for such posts.

I’m not a connector addict, although I do like trying out new connectors.  Partly it’s because I haven’t found the ideal connector system (or systems; I often want some variety so that the same connector type isn’t used for a variety of incompatible uses, and thus you have to be careful where you plug a connector in).

But I still enjoy receiving the occasional Mouser order with some new connectors.  So along with an order for some MDR connectors for my Copley Accelnets, I included connectors I haven’t tried such as:

• Kycon USB B high retention force connector.  The big feature: minimum removal force is increased from 10N (standard USB) to 15N.  I like them; USB plugs come out too easily, but this connector makes it a lot harder for a USB cable to become accidentally unplugged.
• Amphenol USB A locking connector.  The big feature: the connector has a locking tab that grabs onto the little square holes on a USB A-type plug.  That’s even better than the Kycon: it takes over 95N to separate the plug from the jack without unlocking.
• TE/AMP MTE connector.  Nice, affordable IDC connectors, except you need really expensive tooling to use them easily.
• Molex Micro-Fit Jr 3.0mm BMI.  I wanted to check out the blind mate version of the Micro-Fit; I’m still not a Micro-Fit fan.
• Phoenix PST 1.3/8-LV-5.0 header with shroud.  The shroud provides polarization.  The Phoenix PST headers and PT terminal block plugs are a very affordable removable terminal block system.
  • One gotcha: you have to use the shrouded headers with the PT 2.5 series (e.g. PT 2.5/8-PVH-5.0) not the 1.5 series (e.g. PT 1.5/8-PVH-5.0).
• Phoenix ST-Combi connector and ST-Twin terminal block.  I’m looking at using these for DC power distribution.

123D is the standalone version of Inventor Fusion, so it is a direct modeler (not a history based like SolidWorks or Alibre).  So put together free, easier to use (direct modeling), and STEP file import/export, and it should work great for creating 3D PCB models.  There could be some problems, such as assembly limitations (such as a low maximum number of parts), or the EULA (so far the 123D End User License Agreement appears to be the standard Autodesk one, with no mentions of restrictions on commercial use).

I haven’t been able to check out 123D’s PCB prowess yet because I haven’t been able to get it to start successfully.  I’ll give it another try in a while.

Designing PCBs

Simplified software just for creating custom break out boards would be great, but I doubt there is enough of a market for such a program.  So I use Eagle PCB, because of its widespread use (and thus available support).

Affordable PCB design software includes:

• At least 3 open source options, the gEDA suite , Kicad, and FreePCB.  Kicad is probably easier to use than gEDA, but I haven’t used either.  Someday I plan to try out gEDA and Kicad, using the Fedora Electronics Lab Linux distribution installed in a VirtualBox virtual machine.
• Eagle PCB ($49-$1494).  A little overkill for automation PCBs, but works well, and has a lot of support (tutorials, support from CADSoft, SparkFun library, etc).
• PCB programs tied to PCB proto houses, including PCB 123 from Sunstone and PCB Artist from Advanced Circuits.  These programs limit your flexibility (check the links for details), but should be simpler (for example, there shouldn’t be any Gerbers to create and possibly screw up), and are definitely worth considering.
• Various other commercial PCB programs, including Target 3001! (59-2999 Euros), Power Station 32 ($50-$2995), Easy-PC ($477 and up), Edwin XP ($700 and up), Vutrax, Proteus PCB ($249 and up), and DipTrace ($75 to $695).

Getting Your PCB Made

There are many good options, but since I do not know enough to rate them all, I will mention a few:

1. I’ve used Sierra Proto Express for many years with excellent results.  Their newer Web PCB service gives even more options, including longer delivery times (with lower prices).  I always order at least 3 boards, since 3 PCBs don’t cost more than 1.  Typically pricing for the No-touch service is around $110 for 3 PCBs.
2. If you just need 1 PCB at the lowest cost, and can wait a while, consider BatchPCB, since they charge by the square inch.  IIRC, pricing is $2.50/sq in for 2 layer, and typically delivery is 3-4 weeks.
3. If you don’t need hand-holding, have multiple designs, and want lower prices, consider Gold Phoenix.  I had excellent results getting 6 different PCB designs made by them at about $140 for 155 sq in.
4. You might prefer a PCB house that will take the files your PCB design software creates directly; that is a little easier than creating Gerbers.
5. Although I don’t use this option, look at the details and consider if PCB houses with free software, such as Sunstone and Advanced Circuits, are a good choice for you.

Component Notes

I’m still using Phoenix for most of my terminal blocks.  For small quantities, Mouser is still typically best, but check your local distributor for larger quantities; ours is significantly less expensive than Mouser or Digikey.

There seems to be a lot better selection of European-style terminal blocks than there was a few years ago, but I haven’t looked at them in detail (I only have so many hours in a day).

I’m looking at using Phoenix UM holders, since I’d like more size options than the UMK series has.

Don’t forget you can use multiple programs to overcome the limitations of one program.

Open Source

Both NaroCAD and FreeCAD are under active development, but I’m pretty sure neither one is anywhere close to ready for production use.

They are still worth checking out, because they might have enough functionality for what you need to do.

Free Commercial MCAD

These programs typically have a lot of limitations, the terms can change at any time, but they are still potentially useful.

1. PowerSHAPE-e.  Very powerful, but costs money to export.
2. Autodesk 123D.  Appears to be good match for modeling personal PCBs; has STEP import and export.
3. CoCreate PE, now creo elements/direct PE.  Limited import and export, limited to 60 parts, but good to see PTC has moved it into the Creo world.
4. MEDUSA4 Personal.  Available for Windows and Linux.
5. Autodesk Labs Inventor Fusion Preview.  Time limited preview of the Fusion direct editing MCAD software.

MCAD Under $500

1. Alibre PE ($199).  Very limited import and export options.

MCAD Under $1500

1. IronCAD Draft ($595).  Not a full MCAD program (e.g. can’t create parts), but can create assemblies.
2. Alibre Professional ($699).  Adds import/export options and more.
3. VariCAD ($710).  Available for Windows and Linux.
4. IronCAD INNOVATE XG (~$1300).  Meant for conceptual design, but according to the product comparison it includes “assembly modeling within  a single scene”.
5. Alibre Expert ($1399).  Adds CAM, Motion, MoI, and more.
6. The combination of Rhino ($995 list, available for less) and RhinoWorks ($595, adds parametric and assembly capabilities) might work well.
   

Other Options worth considering

1. ZW3D ($2500 for Standard).  ZW3D 2011 adds direct editing.
2. IRONCAD ($4000 and up).  Innovative MCAD.
3. SpaceClaim ($2450 and up).  Well known for easy direct editing.

Update 4/18/2011: Added Rhino/RhinoWorks

Update 5/22/2011: Added Autodesk 123D, updated Alibre PE price.

The advantages include:

• Much reduced wiring time (especially when used with off the shelf cables).
• Competitive BOM cost (possibly even less expensive; I haven’t run the numbers).
• Reduced clutter.
• Enormous component choice, including all kinds of connectors not available in DIN rail terminal blocks, along with semiconductors, resistors, jumper blocks, etc.
• Affordable even for small volumes (I’d say starting at 3 boards)

The disadvantages include:

• Not very flexible — once a PCB is made, it’s hard to change, unlike discrete wiring.  You can add a bit of flexibility by using a number of common PCBs instead of one big, custom PCB (e.g. for 3 axis system, use 1 PCB per axis instead of 1 PCB for 3; then if you need a fourth axis, it’s easy to add another PCB).
• So PCBs are not a good match for unique machines, or ones that might radically change in unpredictable ways.
• Using PCB design software takes some expertise and learning.  It’s not that hard (heck, I’ve done quite well using Eagle PCB, and I’m a software guy), but there’s definitely a somewhat scary learning curve both when designing the PCB and getting it manufactured.
  • Other software might be easier than Eagle PCB, especially software integrated with a specific board house.  But any general purpose PCB design software will have a learning curve, because it has to be able to handle so many design possibilities.
• High voltage and high current take even more expertise.  You can do high current and high voltage on a PCB, but you’ll have to know even more about topics such as creep distances, trace widths, PCB copper amounts, board materials, and thermal dissipation to do it right.
  • So I wouldn’t be making a PCB for a 35kW 480V motor (although it could be done…)
• Your favorite components might not play well.  One reason I use Panasonic PLCs instead of, say, Siemens’ intriguing S7-1200 is that I can easily make ribbon cables to go from the Panasonic PLC to a custom PCB, but I can’t for the S7-1200 (since it uses terminal blocks).

Another option is to have somebody else design and/or make a custom PCB for you (Wago is one possibility, and I’m sure there are others).  I doubt this approach makes sense for small volumes.  For example, I’ve done some research on getting our PCBs assembled, and prices I’ve seen at our volumes aren’t even close to reasonable.

I did play around a bit with PowerShape-e 2009, but I found it hard to figure out.  OK, I didn’t do any tutorials, but I’ve had better luck figuring out other MCAD programs.  Since I now have licenses for Alibre Design and VX/ZW3D and my time is limited, I haven’t used free but limited programs like PowerShape-e or CoCreate-PE in over a year.

The PowerShape-e business model (not feature limited compared to PowerShape, but you pay every time you want to get your data out) doesn’t match well with my requirements (that’s the same reason I don’t like using “free” PCB design software that is locked to a specific proto house).

If you’re looking at acquiring MCAD software, I recommend considering all the CAD design software possibilities, including lesser known programs such as PowerShape, IRONCAD, KeyCreator, SpaceClaim, ZW3D, and Solid Edge.  And I highly recommend reading Deelip’s blog; he is a blogging machine (1000 posts in about 4.5 years), and has written many interesting multi-part series.

But blocks aren’t so great when you’re importing them into Alibre Design (AD).  I’ll look at a few issues by trying to extrude the Phoenix ZFK3DS 1,5-5,08 (1704415) terminal block outline; for example, I might want to model a cover for the end block (1704554).  The files are available in a ZIP archive here Alibre and DXF Blocks.zip.

The DXF file provided by Phoenix uses blocks for all the views.  I removed the views I didn’t want; the resulting file is Phoenix 1704415 Profile – block.DXF, shown below in DoubleCAD XT.  You can see the blocks on the right.

Phoenix 1704415 Profile using blocks

I can’t extrude that profile; I need to remove the pins and the pegs.  But I can’t edit the block in the drawing (left side of screen).  In the Alibre sketch mode, I can only move it, delete it, or copy it.   In the DoubleCAD drawing I can only scale, rotate, move, copy, or delete the block.

But I can edit the block in DoubleCAD by selecting the block in the block tab (shown on the right), and pressing the EC (Edit Content) button.  The block is now displayed in the drawing area, and I can edit it, then press the check mark (next to EC) when I am done.  The final result is shown below and in the Phoenix 1704415 Profile – block for Extrude.dxf file.  Note that when you edit a block, all objects based on that block will update when you finish editing.

Phoenix 1704415 Profile - using blocks, edited

Another approach is to change to a no-block approach by editing the block you want, selecting everything, copying it, closing the block editor, pasting the copied part into the main drawing, and finally deleting all the blocks in the block tab (when you delete a block, all the objects based on that block are deleted).  The result is in the Phoenix 1704415 Profile – No Block.dxf file.

With the no-block file, you can delete the stuff you don’t want in either DoubleCAD or import it into Alibre Design and delete it in AD’s sketch editor.  The no-block approach isn’t good for a circuit board full of blocks, but it works great for a single profile.

There are some other differences between the block and no-block approaches in Alibre Design.  Alibre has a non-obvious approach to pasting in sketches: “normal” pasting (Ctrl-V) always pastes the clipboard content in the same position relative to the origin; paste stamping (Ctrl-T) lets you place it where you want (press ESC when you’re done pasting).

The approach is always the same for getting a DXF file into a sketch: import (which opens an Alibre drawing), open sketch mode, select everything, and then paste it (Ctrl-T or Ctrl-V) into the desired sketch.

So far I’ve found that blocks don’t paste correctly; they get pasted with some sort of an offset, whether using paste or the paste stamper.  Non-block DXF drawings paste correctly.   But it’s easier to move blocks in Alibre sketches: just select them and drag.  To move a non-block figure, you have to select all of it, cut it (Ctrl-X), paste stamp it (Ctrl-T), move it where you want, and then quit stamping (Esc).

Here’s a picture of the finished profile extruded in Alibre:

Extruded DXF profile

I’ve used DoubleCAD XT for all my DXF manipulations because it’s free and it works for me.  You should be able to do the same things with any other high quality AutoCAD clone.  DraftSight is another free AutoCAD clone worth checking out; it’s available on Windows, Mac, and (real soon now) Linux.