Any of you guys remember the stepper driver/motor/setting mismatch issues Makerbot had in the Cupcake and TOM with Gen 4 electronics? @nophead and @Ed_Nisley both made some pretty big “why this is wrong” posts back in the day. (2009 and 2011, respectively.) Ancient history maybe.
Anyway, the old A3977 driver used in the Gen 4 electronics (and a few others) had a reasonably similar chopping scheme to the A4988, so I went ahead and made a StepperSim sheet for it. So now all you guys can pick out new motors and settings for your Cupcakes and TOMs 
Super helpful right? /S
The attached chart shows how badly Makerbot messed up the “recommended” driver settings and motor selection for the TOM. Horrible stepper clipping. Didn’t really matter much with the Cupcake on Gen 3 electronics though, that driver only did half-stepping so you didn’t really see the distorted microstep profile.
It’s actually not a bad driver chip, MBI just didn’t do any meaningful engineering on the stepper system in the Cupcake or TOM. (Most people still don’t.) The root issue here was using a high-resistance/high-inductance motor, and cranking the vref up way higher than could actually be reached.
If anyone is wondering why I bothered with this near-useless historical driver simulator, it’s going to generate some illustrations for my 3d printer design book. There’s a bit in the stepper driver chapter about common issues, and the Makerbot motor selection problem is a good anecdote.
Are you going to reference the two other recent posts on the subject too?
@NathanielStenzel which ones do you mean? The recent Hackaday article? Not sure what the second one is.
Phase circle showing the coil current distortion. In practice, it was doing a step angle sequence where it did four ~quarter steps and then froze in place for a moment at a half step position.
missing/deleted image from Google+
This one references the hackaday page and has some side comments. https://plus.google.com/112209274773346118200/posts/6VDYySemWVL I will try to find the other one or two shortly.
You were actually in this discussion. https://plus.google.com/+AnthonyMorris/posts/S9JPbxphnvG their is a link posted by @Eclsnowman in that post which will probably help. This is the link. http://cabristor.blogspot.se/2015/02/drv8825-missing-steps.html?m=1 That is evidently a blog by Schrodinger Z.
I guess it would help to have some better way to make this information available for the long term. It doesn’t bode well when this information was in the community but then largely forgotten for seven years.
@Jeff_DeMaagd that’s a big reason why I’m writing a book about this stuff. We need some comprehensive, lasting resources. People like Nophead and Ed Nisley who have continuously-maintained blogs deserve a lot of credit for documenting their findings AND keeping the posts up long-term. The old RepRap blog is mostly broken links and missing pics at this point.
It’s unfortunate that the RepRap wiki is so fallow… that was potentially a really good resource, but it ended up being too many pet project pages and not enough technical guidance.
@Nathan_Walkner Way more than six people have already told me they’ll buy it 
Not expecting a stunning success but it’ll a resource out there for people who want to learn. Better than nothing.
@Nathan_Walkner I can grant that. But I found it to be helpful information. I’d been working to learn about improving mechanisms, electronic stuff can escape me.
Using Ryan’s recommendation, I fixed a vexing problem with my UM2: https://www.flickr.com/photos/34962649@N00/28788964024/in/dateposted-public/
@Nathan_Walkner I usually only publicly post once per printer when I open source the design files. I’ll post some builds and ongoing projects soon when I have a chance… At the zoo now
I am sure that if @Ryan_Carlyle puts innaccurate stuff in his book, the community will let him know. If he gives some an advanced copy, he may even be able to double check some things and get some free peer reviews.
I have several competent people already doing draft technical review as I get chapters done. The draft is about 3/4 done at this point. I’ll also send out preview copies to various people before it’s finalized and published. Hoping to have something to show at MRRF 2017.
@Ryan_Carlyle , sounds like a good Kickstarter opportunity to me. 
@Panayiotis_Savva Maybe for marketing. I don’t need any funding to make it happen. Barring deciding to hire professionals for editing and layout, anyway. I think that cost would completely eliminate any possible profit I could get off the book.
@Ryan_Carlyle , if you consider that it costs money and time to write is up. If you get a good finding amount, you could invest in illustrations, graphics design, proof readers, and even hardcopy if that’s your goal. Just saying, a little cash would make an awesome idea even more so awesome
