Printrbot Simple – part 2 – the build

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Printrbot has been continuing to refine their printers as they go along. Since the original Simple beta, they’ve gone through a few revisions. The original didn’t have end stops, this now comes as part of the kit. A fan was added to help temperature control. They’ve added tension adjustment on the strings they use to attach the platforms to the motors. On October 23rd they change the design to use large motors – and even though my order was a day prior, I still received the large motor kit.

These improvements they’ve managed to fold into the same cost, keeping the price the same for the improved product. For previous customers, they offer reasonably priced upgrade options (and instructions) to update their printers. For some parts, they provide the files needed to print your own.

I promise I’ll get off the fan boy soapbox soon, but I need to also mention that they’ve released the designs under a Creative Commons non-commercial license. This is a company that not only delivers great value, but has embraced the community. I’m quite happy to jump in and participate when things are like this, and I’m sure a lot of others are too – this creates a great feedback loop to the company that benefits them via support and (potential) improvements from the community.

On to day one of my Printrbot Simple build – I followed their build instructions and will reference steps (hopefully they don’t renumber / edit the document too heavily). [Edit – it does appear they’ve added some steps, as my numbering appears to be currently ‘off by 2’ later in the instructions – that or my notes were sloppy]

The remainder of this post is terse details with my comments on each step. Not much to see here unless you’re building your own Printrbot Simple. This was the first of three nights I took to do the build (a bit at a time) – for me it was like reading a good book, I didn’t want it to end so I stretched it out a bit.

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Printrbot Simple – part 1 – ordering

I’ve actually been quite active tinkering with things, even keeping notes on what I’ve done with the intention to post here — but I’ve not been getting around to posting anything.

My twitter followers will know I’ve recently got myself a 3D printer and that along with the rest of life has been keeping me busy. This is the first in a multi-part series of posts about my recent adventure.

In October, one of my birthday presents was “go buy yourself a 3d printer”. Super cool! I’ve been drooling over them for a while. First following the Solidoodle, then the Printrbot Simple, MakiBox, and even this $100 3d printer on KickStarter.

Of course with me, there is a big difference between wanting to buy something and actually putting down the money to buy it. Agonizing over a purchase is probably half the fun. You’ll note that all of the choices were fairly economical, this is a toy for me – not a serious tool.

In the end the Printrbot Simple won out. Some were eliminated on price or availability, but the Simple also came in a kit form – and for me building the printer is half the fun.

I ordered it on October 22nd. The order was fulfilled on October 29th and delivered (inside the USA) on November 5th. While I live in Canada, the border is only about an hour away, and sometimes it makes sense to avoid (excessive) cross border shipping fees and simply use a parcel holding service – in this case I used The Corporate Center. When bringing the kit across the border I did pay some taxes on it (about $40) but given that I didn’t pay any tax on the purchase because it came “from out of state” it didn’t feel like a big deal. The shipping cost to Canada was more than I saved, plus there was an ‘unknown’ cost to do the duty/taxes.

The box itself was surprisingly compact: 4.5″x10.5″x10.5″ – weighing in under 8lbs.

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Next up, we’ll start assembling the kit.

Removing Greylisting

This is a follow up article to my post on setting up greylisting with postfix and Ubuntu. While I really like the idea behind greylisting, it was resulting in legitimate email not arriving.

Why it wasn’t working

  1. Frustrating delay for any password reset, at least a 300 second (5 minute) delay for legitimate email from a properly configured email server. This was a known issue, but still annoying.
  2. Recently (mid-August 2013) some hotmail servers (impacting at least @hotmail and @sympatico.ca email addresses) were returning bounces to the user instead of properly handling the greylisting. [Specific servers from my logs: snt0-omc1-s8.snt0.hotmail.com, blu0-omc1-s36.blu0.hotmail.com, dub0-omc1-s5.dub0.hotmail.com]
  3. Other individual servers that failed to handle greylisting correctly. One important example would be the Interac email transfer email servers (notify@payments.interac.ca).

The more I looked at the logs, the more legitimate email I found that wasn’t being delivered.

It was also difficult for people to understand. If a friend sends you an email, it is then bounced back to them due to their sending server not handling the greylisting correctly – they then send you a follow up email some 5+ minutes later, that email will come through just fine because it looks like a second attempt to deliver the original email. The broken sending server will then kept on the auto-whitelist for 30 days or so and greylisting will not be applied.

Any spammer smart or lucky enough to send via my backup mail server would miss the greylisting as that server didn’t use greylisting and email was always accepted from the trusted backup server.

Also, more spam software seems to be retrying now.

Tools. It wasn’t until very recently that I found the postgreyreport script, this is quite useful for generating a report on what was rejected by the greylisting your mail server is using. I’d recommend anyone using greylisting consider using this script to monitor what isn’t being delivered.

I’ll recommend an article I came across while investigating some of these issues. It is supportive of greylisting (which I can’t agree with now) but it does touch on some other techniques. It’s based on OpenBSD / spamd – something not (easily) available on Ubuntu.

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