Merging modern software development with electrons and metal

I’ve been busy lately with a variety of tasks, including buying a car.  I’d enjoy car buying if I had a big budget and was looking at fun cars like a Mini Cooper S Convertible (my semi-practical dream car), but buying a used car for my wife is another matter.

But since it’s been too long since my last post, here are some quick notes:

• The next post on the Eagle PCB and Alibre series is in progress
• I recently picked up a Applicom DirectLink DRL-CNO-PCU CANOpen card.
  • Applicom is now part of Brad which is part of Molex.
  • Anyway, the DirectLink card is a PCI plug in card with a CAN connector (DB9F, first time I’ve seen that) and some sort of x86 processor.  The CANOpen stack is run on the DirectLink board; there’s no need to run a CANOpen stack on the PC side (e.g. CANFestival).
  • DirectLink cards are available for a variety of interfaces (e.g. DeviceNet, Profibus), and share a common API.  They’re meant to be used to interface fieldbuses with SCADA and soft PLC applications.
  • However, I noted that the CANOpen software does show support for DS402 (motion profile).
  • One nice plus is that the software will scan the network for CANOpen devices.  So if I have a CAN device with unknown ID and baud rate, I can just change the baud rate and then let the DirectLink card figure out the CANOpen ID.
  • I plan on writing more about this card, after I finish my current series.
• I managed to get over to Maido Stationery, and pick up some more JDM pens and a 0.3mm Kuro Toga pencil, so I’ll be doing another pen post soon.

Extruding the PCB – Overview

The first step to a complete 3D PCB model is to create the PCB.  The basic approach is to export a DXF outline of the PCB and its holes from Eagle PCB, import it into Alibre, and then extrude it.  It’s not as easy as it sounds.

Alibre Design refuses to extrude sketches with any overlap.  AD V11 did not show where the errors are, but V12 does (this feature alone makes V12 worth the upgrade).

If your PCB border has a non-zero width, Alibre will not extrude the PCB because the four corners overlap.  For some reason, Alibre Design does not accept the way the standard Eagle DXF script creates holes.

I did not have any success getting Alibre Design to extrude the silkscreen or trace layers, nor was I able to overlay the silkscreen or traces as a visible sketch on top the extruded PCB (maybe because Alibre Design does not support surfacing).

When extruding, CoCreate PE is about as picky as Alibre, but (like AD V12) it highlights what it doesn’t like.  SolidWorks doesn’t have problems extruding the standard Eagle DXF output.  VX Innovator is also less picky; I have successfully extruded the silkscreen layer.

I made a couple quick and dirty changes to the standard Eagle DXF creation ULP to fix the holes; the result is dxf-fsw.ulp.

Creating the PCB — Step By Step

1. Open your project in Eagle, then open the Eagle Board editor with your PCB layout.  I used the FP-SMC-1 project as an example; you can download the files here.
2. Make sure your borders have a width of 0.
3. In the Eagle PCB board editor, turn on only the dimension, via, and pad layers (layers 17, 18, and 20).
   

   Layers for DXF creation in Eagle

   

   FP-SMC-1 in Eagle set for DXF creation

4. In the Eagle PCB Board editor, run the dxf-fsw.ulp ULP.
   1. Select a file name for Output file; I used FP-SMC-1.dxf with the appropriate path for my Eagle PCB setup.
   2. The Always vector font, Use wire widths, and Fill areas setting should not matter.
   3. The units do matter: you need to know them when you import the DXF.  I used inches.
   4. Then run the script by pressing OK.
   5. You can download my resulting file here FP-SMC-1.dxf
      

      Running the dxf-fsw ULP

5. Close Eagle PCB.
6. Start Alibre Design.
7. Select the File->Import menu, select AutoCAD DXF files for the file type, select the file (in my case, FP-SMC-1.dxf), and press Open.
   1. File Units need to match the units you used when creating the DXF in Eagle (I used inches).
   2. I don’t think Maintain Projection matters.
   3. Importing Only Visible Layers makes sense.
   4. Start importing by pressing OK.
      

      Importing DXF into Alibre

8. Select the Sketch->Activate 2D Sketch menu  (or press Ctrl+K).
9. Select the Edit->Select All menu (or press Ctrl+A)
10. Select the Edit->Copy menu (or press Ctrl+C)
11. In the Alibre Home window select the File->New->Part (or press Ctrl+Shift+T)
12. Select the Sketch->Activate Sketch menu (or press Ctrl+K)
13. Select the plane to use for your new sketch.
    1. You can name the sketch.  It’s not a big deal in a simple part, but I would recommend named sketches in a complex part.
    2. I used the XY plane.  You can select the plane by either clicking on the plan in the work area, or clicking on the list of planes in the tree on the left (e.g. Planes->XY Plane).
14. Select the Edit->Paste menu (or press Ctrl+V) to paste the DXF drawing into the sketch.
    1. You could select and move the sketch around if desired.
       

       FP-SMC-1 DXF pasted onto the sketch

15. Select the Sketch->Activate Sketch menu (or press Ctrl+K) to deactivate the sketch mode.
16. Select Extrude Boss by menu (Feature->Boss->Extrude) or icon (typically the top right icon).
    1. Verify the correct sketch is selected.
    2. Use To Depth for Type.
    3. Use your PCB thickness for depth (0.062″ or 1/16″ for me).
    4. I reversed the extrude so the sketch is on top (probably doesn’t matter a lot).
    5. Leave everything else with the default settings, except you may want to name the extrusion.
    6. Start the extrusion by pressing OK.
       

       FP-SMC-1 ready for extrusion

17. Save the PCB using the File->Save As menu (Ctrl+Shift+S); mine is available as FP-SMC-1 PCB.AD_PRT
    

    The extruded FP-SMC-1 PCB

18. We are done creating the PCB itself.  Now we have to assemble the board inside of Alibre, so stay tuned.

Here is the FP-SMC-1 PCB as an Acrobat 3D PDF; if a correct version of Acrobat is installed, you can click on the PCB, and then rotate it and more.

I’ve added the Eagle PCB source files for six PCB projects, included the five boards I’ve discussed previously.

You can download via subversion or the new download page.  You can browse with trac.

I plan on experimenting a bit with the format of the download page.

And, yes, I am still working on the Eagle PCB/Alibre series; in fact, I created the download page to support my next post in that series.

What Is This New Series About?

I will create a 3D PCB model using Alibre Design Standard V12 from an Eagle PCB project (I will be using the FP-SMC-1 an an example).  I will not cover every single little step in detail, but I plan on being complete and fairly detailed.

The same basic approach will also work with other MCAD programs; along the way I will include some notes about other design software.

Why Create A 3D Model?

After all, the PCB fab houses want Gerbers, not STEP files.

A mechanical model can  be used many ways, including:

• Checking your PCB footprints (especially if you use STEP or IGES models from the manufacturer)
• Check the mechanical layout of the PCB and the fit of the PCB into a larger mechanical system.
• As an input to simulation software, including thermal modeling.
• To create a beautiful, accurate rendering of your PCB.
  • I will not be covering this.  In fact, Alibre Design Standard does not include photo-realistic renderings; you have to have Design Professional or Expert.

Why Not Create a 3D Model?

Creating a model can take a lot of time, although once you’re experienced and have models for all your common parts, the time should be reasonable.

If you want to be able to share your results widely (e.g. export to STEP files), it will cost some money for the necessary MCAD software.

Spending more money can save a lot of time; for example, if you create your parts correctly, you can use the Eagle 3D ULP to create IDF files representing your board and its components.  Then using even more expensive MCAD software (such as SolidWorks + CircuitWorks), the MCAD software will use the information in the IDF files to automatically create a board model.

Since life isn’t perfect, the board might need some tweaking.  Also, I’ve read that Eagle’s IDF output sometimes needs some tweaking before the MCAD program likes it.

There are at least two programs for creating PCBs in Alibre using IDF files:

• Desktop EDA’s Alibre IDF Modeler ($395)
• IDF Translator (German only)

If you are creating a lot of PCBs at work, I would highly recommend looking at these programs.

What If I Just Want A Pretty Picture?

There are at least two free options for photo-realistic renderings with Eagle PCB:

• The original Eagle 3D project which uses POV-Ray.
• The new Eagle’up project which uses Google Sketchup.

There are some disadvantages to these programs:

• They are not useful for mechanical engineering (using the board as part of a larger MCAD model)
• They do not have large part libraries, and the companies that do provide 3D models typically use STEP, IGES, or Acrobat 3D.
  • However, some file translation could help.  For example, if you can convert a STEP file into STL (which CoCreate PE can do for free IIRC), you can try using the STL to POV conversion utility for Eagle 3D.  You should be able to do something similar with Sketchup.

Why Alibre Design and Eagle PCB?

The short answer: because I have them and like them.  Both programs are reasonably affordable, and fairly popular.  I’d be happy to write about all the other options if I was well paid to do it!

What Are Some Alibre/Eagle Limitations?

So far I have found a few:

1. Alibre Design Standard does not do photo-realistic renderings
2. I have not been able to get Alibre Design to handle PCB traces so far; I can’t extrude them (as produced by the current DXF exporter) and I can’t overlay them.
   1. This could make it harder to model SMT PCBs; on through hole PCBs, it’s obvious where the parts go.
3. Alibre Design Personal Edition (PE) is not usable, since it cannot import STEP files; the cheapest options are either Alibre Design Professional (about $500) or trying to see if you can still grab a copy of Alibre Design Standard (e.g. Novedge still lists it for $185)

Are There Other Affordable Options?

If you want to create a solid model that you can export in STEP format, only other MCAD choice I know of that’s under $1000 and might work well is VariCAD.  The other choices have various limitations, which I might discuss in another blog post.

Or you could use different PCB design software; some programs will do at least some 3D modeling.  For example, there is Altium at the higher end (about $4,000) and Target 3001 at the lower end.  KiCAD (open source) has some sort of 3D capability.

Target 3001 does look interesting, since prices range from free to about 3,000 euros, and it can export to STEP files.  Sometime in the not too distant future I hope to take a look at it.

Three years of blogging — and I’m still averaging about a post every week and a half.

I’ve been very busy in the first half of 2010 with family and work, so I haven’t been able to post as much as I would like.

I am working towards finishing a few posts on creating a PCB model in Alibre from Eagle PCB, but as normal it is taking longer than I hoped.

Once the Alibre/Eagle series is complete, I will be doing a practical motion control series.

My Sakura Gelly Roll Gelato Pen

I still haven’t found another Sakura Gelly Roll Gelato pen.  I spent more time and money than I intended on my quest — but I learned a bit, too.

Why do I like the Gelato?  Because it’s at least a bit better than other good pens (e.g. Pilot, Uniball) with a very fine line (Sakura claims 0.26mm line width for the 04 model I have), wonderfully smooth ink flow, comfortable grip, and retractable design.

My Gelly Roll Bonanza (L->R: Pigma Micron, Regular, Metallic, Gold Shadow, Stardust, Moonlight)

Basically, what’s available at retail are the “artsy” Sakura pens, such as the metallic Gelly Roll models.  The Gelly Rolls are nice pens, but they  are best for fun; for writing, I prefer the feel, thinner line, and retractable design of the Gelato.  My results:

• Michael’s had a few packages of various Gelly Roll types and Pigma Micron pens.  They did not have any individual pens.
• Jo-ann Fabrics had a similar, but larger, selection of Sakura Gelly Roll and Pigma Micron packages.  They did not have any individual pens.
  • Jo-ann does have a much wider range available on-line, including individual pens.
  • Jo-ann’s web and retail selection is much better than Michael’s.
• Aaron Brothers is changing: they had individual Gelly Roll and Pigma pens, but were closing them out.  You can see in the picture that I went a little crazy buying Gelly Rolls.  (It’s for my kids, of course.)
  • Aaron Brothers did not have any multi-pen packages.  It appears they are closing out their more technical and artistic products (e.g. Sakura pens, Faber Castell pencils) in favor of a greatly expanded children’s selection.  The children’s area is pretty nice; I’ll check it out again when it’s close to my kids’ birthdays.

I haven’t had a chance to visit the stationery stores in San Jose or Palo Alto.  But I did find a very nice (but pricey) stationery store while having fun in San Francisco: Maido Stationery.  Actually, the Japantown store is called Kinokuniya Stationery, but it’s run by Maido.  Their other stores are in downtown San Francisco, Santana Row in San Jose, Los Angeles (with Kinokuniya) and New York (with Kinokuniya)

Pilot HI-TEC-C 0.3mm Pen

Basically, Maido is a JDM (Japanese Domestic Market) store — everything is direct from Japan.  They have good selection of Sakura products, including individual pens, along with Pilot, Mitsubishi (Uniball), and such.

If you like pens, you should definitely visit sometime.  They have a wide variety of pens I’ve never seen before, down to 0.25mm width, in all kinds of cool colors.  I ended up buying the finest-line pen that I felt wrote well, a 0.3mm blue Pilot HI-TEC-C (and was lucky I didn’t spend a lot more).  Maido has the hard to find 0.3mm and 0.4mm mechanical pencils — and leads.  I was intrigued by them (I had a Staedtler 0.3mm pencil many years ago), but they were quite pricey, the  real world results weren’t much finer than a 0.5mm pencil, and it’s very easy to break the leads.

But Maido doesn’t have the Sakura Gelato.  The saleslady said it looked like an export model meant for Western countries.  The Sakura America web site says the entire Gelly Roll line was originally intended for export to the US.  In Japan Sakura sells a lot of normal writing pens, but Sakura decided it would be very hard to compete with the US market leaders, so they created a new market with the Gelly Rolls.

Apparently, Sakura was right; in 2003, they introduced the Gelato, and in 2004 some additional models, but it looks like all Gelatos have been discontinued, which is a shame.  The Gelato 04 model has a claimed line width (0.26mm) almost as fine as anything in Maido (0.25mm, 0.28mm) but it writes much more smoothly than any of the super-fine models I tried; I’d say it even writes better than my 0.3mm Hi-Tec-C.  Also, I prefer the retractable pen design; however, if Maido’s selection is any indication, I’d say Japanese prefer pens with caps over retractable models.

So it looks like I won’t get any more Gelatos.  Oh, well, I had fun — and ended up with a lot of cool pens.

I’ve been very busy the last month or so with family matters, so I haven’t had much time for blogging.

But new posts will be becoming this week, and I have a practical, automation focused series planned.

The China Law Blog recently highlighted an article about boutique law firms and why they have been doing well during this recession:

1. Better expertise in the areas they serve (international law in the case of China Law Blog’s firm, Harris & Moure)
2. Better customer service
3. Better pricing (for example, Harris & Moure will do many jobs for a fixed fee).

I feel the same way about many of the smaller automation suppliers; I feel the products are better, the service is better, and the pricing is better than  I get from the automation giants.  OK, they aren’t covered as well by the press (or many bloggers), but that’s never concerned me.  The ones that have been around a while (such as Galil) are going to be in business just as long as the biggies, with a lot fewer strategy changes.

And, when these firms get bought out by big companies, they do seem to get at least just a little bit worse (and sometimes much worse — I can think of a couple cases where I’d find it difficult to buy from them again).

In summary, I do often feel that small is beautiful.

Silicon Valley is filled with stores; I’d say retail is still overbuilt, despite some store closings.  But recently, I had a lot of trouble finding some definitely non-exotic items.

First, I went looking for a 4″ Crescent wrench.  I looked at four stores, including Lowe’s and Orchard; the results weren’t pretty.

I bought a 4″ Craftsman wrench at Orchard about a decade ago, but now Orchard has nothing.  At least Orchard has some good hand tools, such as Bondhus hex wrenches.

I wasn’t impressed with Lowe’s hand tools; about half seemed to be private labeled made in China specials.  They didn’t have any 4″ Crescent wrenches.

Fry’s actually has some nice hand tools, although their selection was better a few years ago.  For example, I bought some really sweet Wiha screwdrivers there, but they don’t sell those now.  And they don’t sell 4″ wrenches.

I finally went to the local Ace hardware store, and found a sweet little 4″ Crescent wrench (made by Crescent).  It wasn’t cheap, but the quality is excellent, and I expect it to last a decade or two.

The second item I wanted was a pen (Sakura Jelly Roll) someone gave us; I really like the way it writes.  So I looked at the Office Depot, Staples, and Target, didn’t find it, gave up, and then found the Sakura web site.  Apparently, their pens are only sold by specialist stores (e.g. art and technical drawing stores).  Sometime I’ll make a trip to one of those stores; they have some really cool sounding products, including pigment ink pens and embossing pens.

Recently, I had what seemed like a simple task: select a DAC (digital to analog converter).  There are hundreds of models, so it should be easy, especially since most of my requirements were not demanding (1 channel, 12-bit or better, 1KHz output rate, 0-10V, low jitter output, and reasonable cost, hopefully <$500).   Even my low jitter requirement wasn’t demanding; I’d be happy with 100 microseconds of jitter; basically, any unit with a decent FIFO buffer and a hardware timed DAC update should work.

But finding candidates was a lot of work.  Early on, I concentrated on USB DAC models, because they have sufficient speed, are self-powered, tend to be reasonably priced, and don’t need a PCI or PCIe slot.

I’ve used Measurement Computing before, so they were one of my first stops.  It was really hard to find exactly which models have FIFO buffers and hardware paced outputs.  I had to do a lot of searching — and reading the full manuals.

The cheapest Measurement Computing model that met my requirements is the USB-1208HS-2AO, which is overkill ($599, high speed USB 2.0, 2 12-bit analog outputs at 1MHz, DAC has 4K FIFO buffer).  As far as I can tell, nothing cheaper has a FIFO buffer for the DAC.

Data Translation wasn’t much better; I had to dig through the detailed specs PDF to discover that the DT9812-10V meets my requirements, and has a 2K FIFO buffer.  It’s $375; DIN Rail mounting is an extra $60.

The final contestant is the Accesio USB-DA-12-8A, which has a 128K samples buffer.  It’s $525; DIN Rail mounting is an extra $19.

For my application, the Accesio looks the best fit; it more than meets all my requirements, I like the large buffer, andI like the DIN Rail mounting option.