Category Archives: Mechanical

3D Printing – Diggro Alpha 5

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Although I don’t do a huge amount of 3D printing, I periodically find the ability to print something incredibly useful, particularly for anything custom or low-volume.

I had been using a Diggro Alpha 3 I bought in 2020 for a long time and it continues to serve well. It is a re-branded Longer LK4 Pro or Alfawise U30 Pro (see here). It competes with the Ender 3, has a 220x220x250mm build volume, Marlin firmware, and comes standard with a variety of features that are options for the Ender like a filament run-out detector so your print isn’t ruined if the filament runs out or breaks mid-print; it can also recover from an unexpected power outage. What really stands out is its very nice touch-screen LCD user interface. Manuals and firmware are available from Longer here. I use Cura as the slicer.

Diggro Alpha 5

Having had a good experience with Diggro, I bought their newer Alpha 5 in 2023. It is similar to the Alpha 3, but offers several incremental enhancements including fully enclosed electronics, UL listed Meanwell PS, a convenient place for the filament spool. In theory, it supports automatic bed leveling, but I could never get that function to work properly. I level it by hand and once leveled, it stays level for many prints; the use of a flexible magnetic bed sticker really helps in that regard.

Through experimentation, I’ve learned a number of things that make 3D printing much nicer:

  • Use a flexible magnetic print bed. I bought a cheap one from BefenyBay for $13.59 on amazon and it works great. The magnetic feature lets you remove your print surface without messing up the leveling and the flexible surface makes it trivial to remove your print (just bend it and it peels right off – no more putty knives). Even better, PLA prints seem to just stick to the slightly textured surface without any painters tape or hairspray. This makes printing *soo* much better. The downside of this particular bed is that the surface is polycarbonate rather than PEI which means it can be damaged if the hot end comes down too far, pushing into the surface. A PEI surface like this is better.
  • Dry your filament before you print. Most filament absorbs moisture and when it does, it causes all sorts of problems: the filament becomes brittle and breaks easily; the prints become covered with stringy fibers, overall results are poor. Fortunately, there are low cost filament driers where you can place a roll of filament and it will use heated air to dry it. I like the Eibos Easdry which has a built in humidistat.
  • Octoprint – I run octoprint on a Raspberry Pi Zero 2W with an old Rpi camera. You must use at least a Zero 2W (not the original Pi Zero W). I tried RPi cameras version 1.3 and 2.0 and both worked great. The RPi connects to my wifi and to the printer. It provides a web interface to monitor and control the printer including uploading files, starting/stopping/pausing prints, monitoring the printer temperature, controlling the printer, and most importantly: monitoring the print remotely via the camera so if things go awry, I can easily abort the print. Octoprint basically network-enables your printer and is an essential feature IMO. You’ll never go back to running back and forth between your computer and printer with a uSD card. Octoprint requires a Raspberry Pi, a camera (strictly speaking, the camera is optional, but it’s so useful I consider it essential), a uSD card, a micro-to-B USB cable (my printer’s USB connector is type B), and a suitable power supply; I use a cheap 15W USB phone charger (make sure it is ETL or UL listed) and a micro-USB cable. The case is printed.
  • I continue to use (and like) Alibre as my 3D modeling CAD software.

3D Printing: Diggro Alpha 3

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I haven’t updated my 3D printing page for a while so this page has my latest thoughts on the subject:

These days, I mainly print using FDM on a Diggro Alpha-3 printer (bought on amazon). It is one of the zillion Creality Ender-alikes with some nice features (particularly the touchscreen control panel and end-of-filament detection). It produces high quality prints (about 10mil accuracy). See the Alpha-3 sub-reddit here.

Diggro Alpha-3

I’m partial to Monoprice PLA+ filament these days. It mixes some TPU into the PLA to produce very nice, very reliable results (see various filaments and their characteristics here). I use a 50C bed, 205C nozzle, and no cooling fan. I print directly on glass with Aquanet Super Extra Hold hair spray for adhesion (cheap, effective, smells nice).

If filament has been out for more than a few days, I still dry it in a food dehydrator (which works really well). I store it in a 5-gallon bucket with silica-gel kitty litter at the bottom and a screw top that seals the bucket but makes it easy to open.

Good prints require the bed be leveled and the nozzle properly gapped; I use a post-it note for the gap width.

Alibre Design

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I am a long time Eagle (electronics CAD) user and decided it was finally time to learn solid modeling for mechanical design. Learning any CAD package is a huge time commitment so even though I already subscribe to Fusion360 from AutoDesk, I value my time and want to invest it wisely so I researched several options. The choices came down to Fusion360 and Alibre Design. Alibre costs more and lacks some of the standard F360 features, but it is available for purchase rather than subscription which I find very appealing for reasons I’ll outline below.

What clinched the deal was my support interactions with the two companies. In the case of AutoDesk, I wanted to know if I could use their discounted CyberMonday pricing to renew my F360 license or if it was only for new customers. Their ‘no’ response took days and confirmed my fear about AutoDesk’s subscription model: it creates incentive to take existing customers for granted and focus only on new sales…more on that later.

By contrast, when I reached out to Alibre regarding some concerns with their licensing model, I heard back within a few hours (on a holiday Sunday!); first from a senior support person, a few hours later, their CEO responded to my question in their online forum, and the next day, I heard from their COO who worked out a creative licensing solution at no additional charge. Mighty impressive. Needless to say, I purchased the top tier Alibre Design package and don’t expect to renew my F360 subscription.

These customer service experiences echoed the experience I’ve had with Eagle CAD since AutoDesk acquired it. I purchased Eagle many years ago when it was owned by CadSoft. They released periodic updates and I bought them if and when they added value. AutoDesk bought Eagle 5 years ago, switched it to a subscription-only model, and integrated it with their new 3D modeling software: Fusion 360. In the intervening 5 years, Eagle hasn’t improved in any ways I care about; if anything, their push to move it into the cloud has made it slow and clunky. Glitzy but rarely used features help sales more than the routine features used daily by real existing users, but with the subscription model, vendors have little incentive to take care of existing customers…a great reason to avoid the subscription model.

I’ll post a review of Alibre Design once I’ve had some time to learn the basics, but if their technical quality is anything like their customer service focus, I expect great things.

Update Jan 2023: I really like Alibre Design. It’s easy to learn and use and is quite powerful. The YouTube tutorial videos are very good and now that I’m learning AD, I can see why everyone I know who does modelling tells me that the skills are easily transferable between programs: the concepts are what really matter and most of the tools (AD, SW, F360) implement them in similar ways.