Merging modern software development with electrons and metal

For my Factory Software Blog projects, the winner is Mouser.

It’s easy for me to order from catalog distributors like Mouser and Digikey, and with their wide range of products, I can get almost everything I need from either one, which is convenient and saves on shipping.  Both have excellent search engines that really help pinpoint the products I need.

Mouser’s result pages are prettier than Digikey’s, but that’s not all.  Mouser shows volume pricing on the result page, allow you to sort by price, and allow you to continue to filter even with less than one page of results.  Typically Mouser is a bit cheaper than Digikey (though not always).

The real reason I’ve done all my Factory Software Blog ordering from Mouser is that that I’ve been choosing a lot of Phoenix Contact Combicon PCB connectors for various interface PCB boards, and Mouser stocks a much wider variety of Combicon components than Digikey.  Digikey won’t sell many Combicon parts in single quantities: you have to buy the whole pack (e.g. 10 parts or 50 parts).   Ugh!

Newark also has a good range of parts but is often pricier than Mouser (although I’ve heard that prices can be negotiated).  Allied Electronics has a better selection of industrial products (such as pneumatics).  But the big problem with both: their search engines are terrible.

One reader puts in a good word for Premier Farnell’s new social forum site.  It might be great, along with other such forums (e.g. TI E2E, ADI’s new one, CNCZone, Control Engineering’s LinkedIn and Facebook groups, etc), but I’m not interested in forums right now.  Been there, done that.

The jumbo distributors like Arrow and Avnet do have the widest range of electronics, but aren’t as friendly to individuals.  Neither are local automation distributors (although I’ve bought a couple items from them), but they typically do have better prices and service than the catalog distributors.  So I use them a lot at work, but they’re too much of a hassle for my Factory Software Blog projects.

It’s not worth it.

Based on my traffic, adding advertising would just about cover my hosting costs, which aren’t a big expense anyway.  But advertising would add a lot of annoying distractions.  The only thing I might eventually add is a referral link for my hosting company, Webfaction, since I’ve been very happy with them.

My big expense is the hardware and software I buy, play with, and then write about here. I’ve spent a lot more on CANOpen servo drives, CAN interfaces, Alibre Design, VX Innovator, connectors, breakout boards, and PCBs than I have spent on hosting.

I have not received any money or gifts for this blog, and will not accept any money.  There are some sample products that I’ve received for free (actually, work related, not blog related freebies) that I will write about, but I will make it clear when the product was a free sample, not something I bought.

One of my biggest costs is the time I spend here: each blog post does take a substantial amount of time to write, typically much more than I expect.  My drafts have an annoying way of expanding.   I don’t plan on taking quitting, but since blogging comes after family and work, at times new posts might take a while to appear.

Recently, I had to select a servo motor.  We had already chosen to use a NEMA 23 mount with a 0.25″ shaft, and had other requirements such as maximum length, torque, speed, and voltage.

I was amazed at the different shaft diameters and lengths supposedly standard NEMA 23 motors have — I recall 0.25″, 8mm, and 0.375″ diameters, and can’t remember all the lengths.  It was even worse when I had to select a NEMA 17 motor a while ago– at least one manufacturer’s supposedly NEMA 17 mount wasn’t the same as everyone else.

Then of course there are all the non-standard mount motors – but I only use those as a last resort, since I’ve already had motors go out of production twice; at least with a standard mount, there’s a possibility of finding a suitable replacement.

Maybe there are other standards: maybe the various European and Japanese 40mm, 60mm, and larger motors really do follow a standard, but I don’t have time to analyze them all.

Connectors are even worse.  I can understand why manufacturers use different kinds of connectors, and I know there are no connector standards.  A motor intended for harsh environments needs a tough but expensive connector, while a light duty motor is much better off with a cheap connector (such as Molex or Tyco/AMP crimp connectors) or flying leads.  But, just like industrial Ethernet, it’s easy to think: do we really need all those choices?  Couldn’t we have just three or four?

I personally like sub-D connectors a lot, since you can get high power (Combo-D), can use crimp pins or solder cups, and choose from a wide range of backshells (including straight, right angle, and 45 degree in metal, metalized plastic, and plastic) and manufacturers.

Of course, pin-outs are even more varied.  For example, on the controller side, Galil (DMC-21×3/AMP205×0 combo), AMC (DX30, DX60, etc), and Copley (ADP series) all use HD15 connectors for feedback, but each one uses a different pin-out.

Oh, well, at least commutation and incremental encoder signals are pretty standard: three signals, either RS-422 differential or single ended (TTL or open collector) –  except if you use some Japanese motors (e.g. Panasonic).  And I’d better leave absolute encoders for another time…I’m not even sure how many “standards” there are for them.

Premier Farnell, a major electronics distributor (subsidiaries include Newark and Farnell), has purchased Cadsoft Computer, developer of Eagle PCB.

If you’re interested in the financial details, go to the press release.   Since I use Eagle as my primary PCB design program, I’m interested in what might happen to Eagle.

Companies in another business that buy a company for “synergy” often destroy the business; examples include Exxon buying Zilog.  It looks like Premier Farnell is buying Cadsoft to increase their business, by increasing the integration between Eagle PCB and their distributor companies (e.g. so it’s very easy to specify and order parts from Newark in an Eagle design), similar to what Sunstone, Digikey, and NXP are doing with PCB123.

I am curious to see what changes the new owners will make.  Will they continue to invest in Eagle PCB to make it better?  Will they change the current pricing?

Update 9/9/09: VX Innovator is now $295 (Americas, India, Africa) until September 30, 2009.  Check here for my latest MCAD news.

Since I’ve been posting a lot about affordable Mechanical CAD software, here’s an update on two great deals:

• Alibre’s $99 offer for Design Standard V11.2 ends on September 29, 2009; also on sale for $99 are Alibre Translate and Alibre Training Bundle.  The maintenance contract is still $299, and includes the upgrade to V12 (due on 9/29/09).
• Time to give some attention to VX Innovator: it’s on sale for $195 until September 4, 2009 for Americas, India, and Africa (with a note that price will increase to $295 — we’ll see if that’s a permanent price cut).

I’ ve been playing with Innovator for the past couple days, and will probably buy it, too.  Some initial comments:

• I’ve had problems installing it on two XP systems, but did get it to install on a Vista (yuck!) system.
• There’s not much about it on the web.  I’ve tried searching for VX topics, and had a hard time coming up with useful results;  there’s much more information available on Alibre and CoCreate.
• I was able to get it do some basic stuff without reading the manual, but with a fair amount of fiddling; overall, I’d say it’s not too difficult to use.
• It can do some things Alibre can’t do, and works in a very different manner (which is good — if it was very similar to Alibre, Solidworks, Solid Edge, etc I wouldn’t be interested).

BTW, I’m not interested in running cracked copies of software (e.g. Solidworks).  I’m interested in using software that’s affordable for anyone to use commercially, and I think that companies that produce good software should be rewarded.

I’ve blogged recently about Alibre’s crippling of Design Xpress.  Well, for a limited time, Alibre is now offering Alibre Design Standard for $99; I like this deal and have already paid for a license.

I am using MCAD software to model the PCBs I design because I can catch several types of design errors, including incorrect footprints and mechanical interference.

My requirements are pretty simple; what I want is an affordable system that can:

• import STEP and IGES files, since I want to use the manufacturer’s models if at all possible
• import and extrude DXF files, so I can easily create a model of the printed circuit board itself
• create assemblies using a fair number of parts (>50 should  be enough most of the time)
• export to STEP file (required) and 3D PDF, so I can share my work with others who aren’t using the same CAD software
• be fairly easy to learn and use — I’m primarily a software guy, occasionally designing PCBs, but I’m definitely not a mechanical designer.
• cost under $250

None of currently available free commercial MCAD programs meets all these requirements.  For example, I am fond of CoCreate PE, but it does not export to STEP or 3D PDF, and is limited to 60 parts per assembly.

At $99, however, Alibre Design Standard meets all these requirements, so I will be using it now for all my PCB modeling.  I still want to experiment with and blog about other possibilities, but I don’t expect to get around to that anytime soon.

Some commentators feel this is a desperation move by Alibre.  I think it is a good deal, because:

1. Alibre is getting a lot of publicity
2. They are getting cash flow from Design Xpress users they wouldn’t have gotten otherwise (I’ll call these people, including myself, the non-serious users).  In my case, Design Standard currently isn’t worth $999 (or even $500) to me, so Alibre received $99 from me that they wouldn’t have earned otherwise.
3. Since Alibre has not cut their other pricing, and support and maintenance is not included (Design Standard + 1 year support and upgrades is $398), their support costs are not going to skyrocket, and they probably won’t be devaluing their products.
4. They will still be getting more money from the “serious users” (who would be willing to pay >$500) because these users will be paying annual maintenance.
5. They have increased their chances of upselling in the future.  Once I am used to modelling with Design Standard, I am more likely to pay for maintenance or upgrades in the future.

Go here for my latest MCAD news posts.

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.

IDEC LW7L Push Buttons

Industrial style does matter.   That’s one reason I like IDEC’s LW7L flush mount pushbuttons.  Recently I was looking at some of our old equipment with Telemecanique pushbuttons that stick out over 5/8″ — those buttons are functional, but look dated.

The LW family of buttons is extensive (well over 10,000 combinations are available), but the models I like are the  LW7L-M1C64MG and similar.  What is good about them?

• They only need a light touch to operate (lighter than some other IDEC push buttons such as the HW2L series)
• High quality
• Long life LED lights available in amber, green, red, blue, white, and yellow.
• Powered directly by 24V (no resistors to worry about — I’ve destroyed LED lights from other companies).  6V, 12V, 120V, and 240V models are available, but I always use 24VDC.
• They are easy to install.
• The price is reasonable (around $30).  The Telemecanique buttons were much more expensive.   They aren’t the cheapest (e.g. the HW2L buttons are about $20), but I think the difference is well worth it because of the next point.
• They look great, with the square shape and flush mounting.  The traditional round, stick out 22mm push button makes equipment look like a retro-encabulator from the 1950’s.  I consider the extra cost over the HW2L buttons a marketing expense.

I also really like IDEC’s XW series of E-STOP switches — especially the models with a LED light.

I enjoy reading mysteries, especially the classics (“Golden Age”).  I have no interest in police procedural novels.  Most of the time I’m not interested in hard-boiled detectives (e.g. Mickey Spillane).  I remember one time listening on XM radio to a old time radio detective show – it was filled with over the top metaphors and cliches.

But the best hard-boiled writers are good.  To be exact, Raymond Chandler and Dashiell Hammett are good, and I’ve read most of their stories.  Recently, I bought Chandler’s The Simple Art of Murder — and of course I read it immediately, and enjoyed it.  Those short stories are a nice change from the Marlowe novels.

But I don’t agree with his introductory essay on detective novels.  Chandler says the goal of fiction is realism — but it’s not: fiction exists to tell a story, whether sung by a bard, recited by a poet, printed in a novel, or shown on a movie screen.  Ideally, fiction should tell a story about interesting characters with style, and illuminate part of the fascinating world we live in, a world filled with all kinds of people (I strongly agree with Chandler that there is no such thing as a boring topic).

No fiction is realistic: Chandler and Hammett are not exceptions.  Hammett’s The Gutting of Couffignal is no more realistic than The Red House.  Chandler’s stories, set in Los Angeles, make Los Angeles sound like what I imagine Las Vegas was like in its gangster days.   If Chandler was realistic, his stories would’ve ended quickly, because his detective would’ve been shot and killed, or retired with multiple concussions, instead of persisting through many narrow escapes and thorough beatings.

And I don’t doubt that LA has had, and still has, many problems with gangsters, gangs, and murder, but I don’t think his stories ever matched the typical life of most inhabitants of Los Angeles.   Frankly, I suspect Las Vegas was never really like its gangster image for most people, either.

I could argue that for a murder novel, you need to talk about those who are likely to deal with murder, such as detectives, gangsters, and the police.  But I don’t believe most murder and violence were (or are) caused by gangsters.

And it’s definitely not realistic today.  Where I live, most murders aren’t gang related; none of them sound at at all like something from Chandler or Hammett.  There aren’t any gambling joints.  Frankly, Jane Austen is a lot more realistic — I know several people who sure act a lot of characters in her novels.

But realistic ficture isn’t what we want.  Heck, even look at “reality” TV — of course, it’s time compressed to only show the more interesting interactions, and the producers try to set the show up to generate conflict.   I know most of my life wouldn’t make for a interesting novel.

In an article in Control Engineering, Steve Feketa of Rockwell claims that magnetic linear encoders are available for $200 for a 1 meter encoder, while optical linear encoders can cost up to $2000 for a 1 meter encoder.

If you’re paying $2000 for an optical linear encoder, you’re either getting a very high resolution encoder, a very rugged encoder, or some golf at the country club for the encoder manufacturer’s sales team.  I can buy a nice optical linear encoder with a 1 meter scale for substantially less than $1000.

But I can’t find any information on inexpensive magnetic (or magnetorestrictive) linear encoders.  I do know of inexpensive optical linear encoders from US Digital and Avago that are under $200 for 34″, but they are hard to mount and the resolution is only 12.7µm.  I found that Heidenhain, Renishaw, Netzer, and Temposonics (magnetorestrictive) all make magnetic linear encoders.   I couldn’t find any pricing, and I’m not going to spend a lot of time trying to get quotations when I’m not ready to buy one.  I suspect that Netzer is the only one that might be close to $200 for a 1 meter length.  OK, New Scale Technology’s Tracker is probably under $200, but its length is only 8mm.

Why am I interested in low cost linear encoders?  Because the current cost of linear restricts their use to when I really need them (I’ve used linear encoders twice in > 10 years of machine building).  Even a low resolution linear encoder is helpful to minimize problems from backlash, and to provide feedback for linear motors.

For the hobbyist, eBay is one solution.  I recently bought two MicroE M2000 linear encoder read heads + electronics on eBay for a very reasonable price.  True, I don’t have the scales, but I’m not sure where I’ll use them, so that’s OK.