Merging modern software development with electrons and metal

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Good Stuff: Affordable 19″ Rack Mount Keyboard Drawer

In the past at work we haven’t used rack mount keyboard drawers because all the models we could find were over $200.  Instead, we designed our own that mounts on top of a rack mount PC.  This design works fine, but it requires modifying the computer case.

Since we’re making some changes, I took another look, and finally found an affordable 19″ 1U (1.75″) keyboard drawer: the Penn Elcom EX6301B, which is available from Newark/Element14 here for about $80.

Actually, it’s not keyboard drawer: Penn Elcom calls it a laptop drawer.  But it will work fine as a keyboard drawer as long as you are using a compact, slim keyboard such as the Adesso AKB-410UB.  A standard keyboard is way too wide; my beloved Cooler Master Quickfire tk is narrow enough, but it’s too tall.

I’d also highly recommend using a keyboard with integrated track pad or trackball (the AKB-410UB has a track pad).  With a narrow enough keyboard, you might be able to tuck a low profile mouse into the space, but you’d probably want a mouse pad, too, so you’re not running the mouse over the drawer’s mesh surface.

Penn Elcom doesn’t provide a lot of information (just some very basic dimensions), so we ordered a drawer to see if it would work — and decided it would.  The build quality appears good, too.


May 30, 2015   No Comments

Sometimes Paper Is Better Than Tech

If you’re one of the elite few who has followed my blog for a while, you know that I like quality pens, pencils, and paper, as well as technology such as 3D Mechanical CAD.

I’ve been working on the electrical portion of a new machine, and this week I started on the layout.  We normally let our tech do the final layout since he does the actual wiring, but I need to make sure everything will fit, and with his help, want to get as close as possible to the final arrangement.  (Ideally, I want to work with our mechanical engineer and tech to get all the DIN rail and component holes placed correctly, because it’s a lot better when these holes are made by the sheet metal shop.)

I thought about trying to use 3D MCAD, but decided instead to cut sheets of vellum to match the panel size, and print life size profiles of the various components.  (I used vellum because I can easily tape and re-tape the cutouts to it).

This approach works well because:

  • I don’t have to create 3D models.  Some manufacturers do not supply 3D models.  Using 2D prints, I can use a PDF (by using Print View and scaling the output – thanks Adobe!), a 2D file such as DXF or DWG, or 3D (by scaling the print or creating a projection).
  • It’s much quicker to move the component prints around.
  • And, to be honest, I like the tactile touch of moving the paper cut-outs around and that everything is life size, not downsized on a smaller computer monitor.

Doing a full 3D model does have some advantages; working in 2D, I have to make sure I accommodate how deep the components are.  But even in 3D, you have to add extra space for hard to model items like cables.

March 28, 2015   1 Comment

Another Way To Make Your Own Metal Buttons

I have to say someday I’d like to make my own metal buttons.

In the past, I’ve covered Microchip’s mTouch metal-over-cap technology (here and here), which uses capacitive technology.  Microchip has a groovy app note which shows some of the ways you can use it, and has an eval kit available for ~$150 (base mTouch kit plus metal over cap accessory kit).

Now TI has a reference design for creating your own metal buttons using TI’s inductive sensor technology.  TI’s reference designs provide that: a reference design with layout, calculations, and notes.  You can’t buy them pre-made, but you can use them as a good starting point.

I’ve glanced through the manual for this reference design, and it is full of good info – and the design is pretty neat, too.  For example, it includes two different haptic types, ERM/LRM and piezo.  I have the HapTouch Booster Pack which features the same ERM/LRM haptics technology, and I’m not too impressed – it’s similar to the haptic feedback from a current smartphone.  (Note that I think the problem is with the basic ERM/LRM technology, not the controller).

Other approaches to non-moving metal buttons include piezo electric and ultrasonic.


March 19, 2015   No Comments

Awesome Pen Swag: Frixion Ball 05 from NEC/Tokin

NEC Tokin Frixion Pen

NEC Tokin Frixion Pen

NEC Tokin Frixion Pen

NEC Tokin Frixion Ball 05

I swiped a lot of pen swag at the Photonics West 2015 Exhibition, but NEC/Tokin’s giveaway deserves to be highlighted: a Pilot Frixion Ball 05 retractable erasable pen with 0.5mm tip.

NEC/Tokin makes an interesting mix of materials, sensors, and components such as capacitors, chokes, and relays.  Somebody there must like pens, because the Ball 05 isn’t a cheap pen made to be customized.  It’s a cool pen that’s not even available at retail in the US (and is currently $3.80 at JetPens).

My theory is that NEC/Tokin has been infiltrated by a secret pen addict – and I’m very thankful 🙂

Now onto the pen…this is my first retractable Frixion, but not my first Frixion.  I still have mixed feelings about Frixions, but this one is definitely a keeper.

I’m still getting used to the knock being the clip – half the time I still press the eraser, but nothing happens….of course, Pilot’s choice makes sense, it just takes a little getting used to it.

I like the tip size (05=0.5mm).  I also like the tip size of my Frixion Point 04 (0.4mm), but I find the US market Frixions to be too big for my normal writing.  On the other hand, the black ink isn’t as dark as a gel, and the tip isn’t as smooth as a gel either.

Frixions do have a reputation for running out quickly; I felt my US market Frixions didn’t last very long, but my Point 04 is still going strong, so I hope this Ball 05 will be similar.

March 8, 2015   1 Comment

Ixxat USB to CAN Compact V2 Cable Problems

We’ve used the original Ixxat USB to CAN compact interfaces for years without any problems.  The Ixxat is inside the machine, with its USB cable (a type A male) attached to a L-Com panel mount USB adapter (type A female to type B female), which is then connected to the external computer using a standard A to B USB cable.

Since the original USB to CAN compact is no longer available, we have switched to its replacement, the Ixxat USB to CAN compact V2  — only to discover the V2 wouldn’t work!

After extensive trouble shooting, we found that the V2’s worked fine when directly plugged into a PC, but most of the time did not work when inside the machine.

There might be other solutions, but the one we found was to add an USB active extension cable inside the machine between the USB panel mount adapter and the V2.

The V2 is quite similar to the original, but supports USB 2.0 high speed communications.  It also requires a very recent device driver.

February 27, 2015   2 Comments

Robot Primer 13: Why Use Work Coordinates

Since Work coordinates are transformed into Base coordinates in the end, why bother?  Why not just use base coordinates?  Here are some possible reasons; I’m sure creative programmers have come up with others.

  • Using Work coordinates can be more natural.
  • Using Work coordinates can save re-teaching points.
  • Palletizing
  • Using dynamically updated Work coordinate makes complex situations such as picking and placing from a moving conveyor easy.

Next I’ll look at some examples in more detail

Using Work Coordinates To Save Re-Teaching

If we use base coordinates and the robot’s base coordinates change, then all the points have to be re-taught.  However, if we’ve used world coordinates, all we have to do is to add the offset between the old and new base coordinates, and we’re done.

Some reasons why the robot’s base coordinates could change:

  • Robot needs to be re-calibrated
  • Robot needs to be replaced by another robot of the same or possibly different type
  • Moving the whole base plate to a different robot cell
  • If base plate fabrication is precise enough, to allow easier production

Let’s look at a simple example using a simple assembly robot.

Simple Assembly Cell

Robot Primer World Coord 1

This imaginery work cell uses a robot to:

  1. Pick up the circular yellow bases from the top left pallet (defined by points P1 to P4)
  2. Place the base in the assembly fixture (P13) and add glue
  3. Pick up the blue part from the bottom left pallet (defined by P5 to P8) and place it onto the base.
  4. Move the completed part to the inspection fixture (P14)
  5. Finally move the inspected part to the output pallet (defined by P9 to P12).

The base plate is big blue rectangle, and the base coordinates are represented by the even larger gold rectangle, with the coordinates for P1 shown (54.5mm and 85.0 mm).

My example is simple and easy, there’s no need for additional complications such as work coordinates, right?

Work Coordinates to the Rescue

But now suppose the robot breaks down and is replaced by a new robot, with slightly different base coordinates (represented by the bold red rectangle).

Robot Primer World Coord 2

As you can see, the position of P1 has shifted quite considerably on the base plate.  So we will need to re-teach all 14 points.

No big deal, right?  But now suppose the pallets and fixtures and interchangeable so we can assembly 10 different types of parts.  Now we have to re-teach 140 positions: ouch!

Unless, of course, we used work coordinates – then all we have to do is change the offset so that the work coordinates for the robot matches the work coordinates for the old robot.  Now a little bit of extra work pays off: we only have to teach 1 work coordinate instead of 140 positions.

Personal Note

I actually saw this situation; a robotic system I serviced had its robot re-calibrated, and the program used base coordinates, so all the points had to be re-taught.


January 24, 2015   1 Comment

Daiso Adventures

Over the past few months, I’ve had fun checking out the Daiso Japan store near Mitsuwa marketplace in San Jose.  The good side is that most items are $1.50, so when I see something new and cool, it’s hard to resist the temptation to add it to the basket to try it out.

Recent temptations have included

Daiso B5 Grid Notebook

Daiso B5 Grid Notebook

Daiso Grid Notebook - Inside

Daiso Grid Notebook – Inside

This red notebook has paper with a grid design.  I’ve never seen a grid notebook at retail, but I’ve been curious to find out if I’d like it, so I couldn’t resist the temptation of a mere $1.50 for 80 sheets of B5-sized grid goodness (the grid’s dots are at 5mm intervals).  My initial impression is, yes, I like it a lot.


This graph notebook with a translucent blue plastic cover was a no-brainer, also at $1.50 for 60 sheets of A4-sized paper.


My kids love these funky pencils with cute designs and a bunch of tips.  They’re a bargain at $1.00 for a pack of 8.

Daiso A4 Copy Paper

Daiso A4 Copy Paper

A4 paper comes and goes at Daiso, so I jumped at the chance at grabbing several 110-sheet packs for a miserly $1.50 each (A4 paper is double that price at Staples or Amazon, and is stratospherically priced at Kinokuniya/Maido).  Since it’s copy paper, I’ll have to see how does in my inkjet printer.


I might prefer LED light bulbs, but at $0.50 for these 32W, 2100 lumen CFL bulbs, I couldn’t resist picking up a bunch.

The Downside of Daiso

I’ve seen lots of cute and neat things at Daiso over the years (such as brush pens, cute stationery, cute sketchbooks, affordable handy storage boxes, made in Japan dishes, unique egg timers, and more), but it’s kind of like Costco because:

  1. It’s so tempting to add “just one more bargain” that you get surprised at check out time.
  2. Many items are here today, gone tomorrow.  Just of the items I’ve shown, last time the blue notebooks were gone, and the cute pencils have been replaced by boring pencils.  A4 paper has always been hit or miss (sometimes nothing, sometimes only colored paper, sometimes great selection, and so on).
  3. It’s not always a bargain.  Some items aren’t worth a $1.50.  Some items are sold in such small quantities (such as the wire frame storage) that when you add up all the $1.50 items you need, it’s not so cheap.
  4. Inventory can vary a lot store to store.  Daiso has a wide of items, but many of the stores are pretty small, so they get a different assortment of what’s available at the moment.

January 17, 2015   No Comments

One Reason I Love Automation

Parker Bayside R100D

Parker Bayside R100D

One reason I love automation is that I get to play with cool stuff like this Parker Bayside rotary stage.  It’s a jewel; besides have cool specifications, it just feels so good in my hands – and looks beautiful.  The LED angle display is another groovy touch.

There’s a little history behind this purchase.  Many years ago, I got to evaluate its big brother, the R200D, at work, and fell in love.  Unfortunately, the R200D didn’t work out for that application, but when I saw this R100D at a semi-reasonable price (and much cheaper than new, which would around $4,000), I couldn’t resist.

It’s a direct-drive rotary stage, so there are no gears, just a big brushless servo motor, bearings, and a super high resolution encoder.  One down side of the direct drive is that the rotary table can spin when there’s no power, which can be a problem.

For initial testing, I connected it to a Copley Accelnet ACP-055-18 with a Logosol LS1148 power supply, and used Copley’s automatically generated parameters.  That doesn’t seem like the ideal combination; either I need a different drive with a higher voltage power supply, or I need to do some serious tuning.

Another reason I love having this stage is that it’s so different from all the other motors I own.  For example, it has 12 poles (all my other motors have 4 or 6 poles), and an inductance of 50 mH.

Blog Notes

Since many of my posts take quite a bit of work to create (especially the series posts, such as the Robot Primer), I am going to try to reduce the size of each post so I can provide more frequent content updates.

November 14, 2014   No Comments

Cool Components: Ultra High Speed Motors And Drives

Most motors I’ve seen spin at the leisurely rate of 6000 RPM or less (heck, many are limited to 3000 RPM).

My Emoteq BH02300’s can do 20,000 RPM.

I’ve drooled over the specs for motors from Emoteq, Pittman, and Maxon that can do 60,000->100,000 RPM.  (Yes, I’d love to own one).

But a Swiss company, Celeroton, takes the cake: they have motors and controllers that can do 500,000 RPM!  Those must be totally groovy.

Celeroton sells brushless motors, drives, and compressors that use  their motors and electronics.  The drives have a minimum speed of 5000 RPM; some models can handle up to 1,000,000 RPM maximum speed.  The drives (or inverters, as Celeroton calls them) are available in 400W to 3Kw models, and are sensorless (no hall effect, encoder, or other sensors required).

A friend is looking into using the Celeroton drives with a merely fast motor (~100,000 RPM).  If I get any real world feedback from him, I’ll update this post.

November 4, 2014   No Comments

Common Equipment Failures

Most of the time, industrial equipment is rock solid.  However over the years, I’ve noticed a tendency for certain products to have characteristic failures or problems.  Examples:

  • MEI PCI/DSP Motion Controllers and blown I/O.  The PCI/DSP is pretty expensive motion controller, and as befits its price, has opto-isolated I/O, but the general purpose I/O is not protected against over current, so anything over say 20 mA will kill the opto-isolator.  The result: blown I/O and, if you’re lucky, a $500 repair bill.  We learned pretty quickly to make sure we always had appropriate current limiting resistors.
  • AMC DX15 and DX60 CANOpen servo drives have the blinking red light.  The drive powers up, the red light starts blinking, and the drive stays mute: it will not communicate over the CAN bus (and there’s no alternate port to try).  I’ve done some troubleshooting, but haven’t made any progress.  Of all the DX15/DX60 drives I’ve bought from eBay, probably about 50% had this problem (yes, an unfair sample, since the good ones are less likely to get on to eBay.  AMC is a good company, but this record indicates that the DX has a design weakness).
  • Parker ACR9040 Motion Controllers seen to have an easily blown 24V power supply, based on eBay: I’ve seen a few advertised as “won’t power up”, and I bought one that was in “unknown condition” that won’t power up (its physical condition is fine).  I’ve spent a little time troubleshooting, but haven’t found the problem yet.  On the plus side, I’ve enjoyed taking it apart and looking at Parker’s design decisions.
  • I’ve also had bad luck with Elmo servo drives off eBay, with only 1 of 3 working.
  • I have a number of old servo drives with broken halls or broken encoders.  My guess is too much heat for the halls, and too much mechanical shock for the encoders (one even had broken glass).

Now it’s time for some screw-up stories that were totally operator error:

  • One day many years ago, as I came in the back door, I was greeted by blue fireball about 1 foot in diameter.  A tech was live troubleshooting a variable speed conveyor motor, and accidentally shorted out the motor driver, causing the fireball and the top of a driver chip to vaporize.
  • More recently, I was going to measure the current supplied by an AMC PS300 unregulated linear power supply, but had my probes setup wrong, so I shorted across the power supply.  Result: a welder!  The meter and power supply survived, but my meter probe tip melted.
  • I had a weird problem with a FP-Sigma PLC output partially failing.  The PLC’s light was coming on, but the relay driven by that output wasn’t.  The problem was that Common at the relay coil was about 2V different from the PLC’s Common, and over time that destroyed the PLC’s output.  On the other hand, I’ve shorted Panasonic PLC’s (easily if you accidentally swap the input and output cables) and they’ve always survived.


October 22, 2014   2 Comments