After struggling with my crappy Mendel for most of a year,

(Mike Thornbury) #1

After struggling with my crappy Mendel for most of a year, I’ve bitten the bullet and decided to buy a new machine. Having seen the quality of prints the Prusa i3 gets, and how much the quality of machine has improved over the last year, compared to what I got with my Mendel, I am pushing out the boat and spending US$270 (delivered) for a new printer.

I have a Bondtech extruder I will be putting on it and a bunch of different controllers, including a Smoothie 4x, a Due-based RAMPS shield, running TinyG2, and a modified Melzi with Ti DRV8825 drivers to try. I will make it Bluetooth-enabled, might even look at fitting an ESP8266 somehow.

The unit comes with a 12v PSU, but I have a range of 24v, 30v and 36v, so I will use what suits… I have a couple of sets of optical limit switches which I will use in place of the supplied mechanical ones.

The kit itself should be a quick and painless build, being laser-cut 6mm acrylic sheet. It seems to use ‘proper’ drive screws, rather than the threaded rod of my Mendel, and aluminium linear bearing housings.

It’s amazing what a year brings -the Mendel, as a kit, cost over $500 and required so much fettling to get to work. This i3 has proper metal sprockets and what looks like a decent extruder.

I will recycle the Mendel into something else -maybe a PCB CNC with my Dremel or as a little acrylic CNC for smaller jobs than I put on the 8x4. Or even as a new design of printer for doing donkey work. Who knows?

I will post my impressions of the build and subsequent prints.

(Keith Applegarth) #2

Keep us posted. I’d like to see how it arrives and how long it took to ship. it looks similar to the model Hiboson is building on his youtube channel.

(Ray Kholodovsky) #3

Let us know how the acrylic frame pans out, I usually warn people against that.

(John-Paul Hopman) #4

Is the i3 really that much better of a design then the Mendel? I can’t help but worry that you will continue having the same problems with your new printer as with your existing one.

(Mike Thornbury) #5

It is what it is -if you are careful with screwing into acrylic, it’s a great material -dimensionally stable, strong, easy to work with and modify. The kind of forces you get with this sort of moving-bed printer isn’t going to stress it at all. And there’s some nice touches like belt tensioners which my Mendel didn’t have.

I have a bunch of acrylic I use for lamps and the correct cement for joining it, so I will likely cement the major frame pieces for additional strength.

I was going to make an i3 out of MDF, but the price of this one is so good, I probably couldn’t buy the parts for that price.

(Jeff Para) #6

I’ve worked with one…not bad for the price…I just don’t like the flat frame. I’m using an i3 derivative of my own and I prefer the boxed frame design…which is suspended by the y axis rails (my own design) which I feel is more stable than an i3.

(Mike Thornbury) #7

That’s what I will end up doing, I suspect -make an mdf box on my CNC and fit the moving parts of the i3 into it. That will give me the opportunity to enclose it… But that’s some way off…

(The Hozza) #8

I moved over to an i3 a couple of months ago and haven’t looked back, however I custom built onto a 6mm aluminium frame.

(Mateusz Perlak) #9

@Mike_Thornbury if you have access to CNC, give a try to with your old vitamins.
Prices of kits went down pretty good, same for components you can get for printers.
I started over 2.5 years ago with kit for $799 on prusa mendel and after that printed and assembled other printers, still having my original prusa mendel on desk - I might get it rebuild to other printer but I just can’t disassemble - many memories.

(Mike Thornbury) #10

Thanks for the link @Mateusz_Perlak I wish I had seen that sooner :slight_smile:

I have got most of a XY/H plot design complete, which I will use with my old parts to get an R&D platform off the ground. I’ve been working on it for a while now…

The problem is, paying work gets in the way - like Arcade cabinets and speakers…

(Mike Thornbury) #11

Well after reading a few adverse comments about the delivery time, it arrived today - I paid for it on the 23rd, so from CC to DHL at my door, 4 days.

Pretty happy with that - especially as we normally are like the Bermuda Triangle of deliveries - it can take 6-8 weeks to get mail here.

Tommorow we unbox and start assembly - I imagine it will be done in a few hours.

(Mike Thornbury) #12

And just in time for the third-world internet gremlins… No net for three days.

Assembly was a breeze, cabling made much easier by their already-terminated end stops and steppers. But… A broken piece of acrylic would probably have stopped someone else -luckily I have tons of parts and was able to fabricate a replacement.

And their default settings for the Marlin firmware are way out… Waaaaaaaaayyyyy out.

So if their idea was to make an out-of-the-box DIY kit, they failed a little. Still have to go through tons of calibration, and being Merlin, needs recompiling every time… Aaaaargh! Having no net could have been a problem, but I had the sw already, so it didn’t slow me, but there are no instructions, even describing what firmware is running or basic calibration

But there are many, many pluses. Good level of components and generous numbers of spare nuts, bolts, cables, wrapping, tape, etc. every acrylic cut was clean and no hangovers,

Good instructions (only one error I caught -which stumped me right at the beginning, 6mm bolts stated on the video, but 16mm were needed). It was obvious when I opened my eyes and saw what he was using.

So, overall a mix of ‘pleasantly surprised’ with ‘that could be better’.

For under $300 delivered, I think it represents excellent value for a first printer, but you would need to be more experienced than a ‘first printer’ kinda guy.

I have a lot of resources and am familiar with building all sorts of motion control devices, someone less familiar may have struggled. And the broken part is just bad design -it’s too weak in acrylic, either needs a better solution, or the part needs beefing up.


7/10 for completeness, let down by documentation and software on the CD and unidentifiable firmware.

6/10 for component quality -acrylic is an easy build, but they just took the i3 design and replicated it in plastic, without thought to durability -in just one area, really, but a critical one. I hacked a solution, but it’s inelegant and if I was selling these, every one would eventually be returned for the same thing. The MKS controller is pretty good and they have made it fairly foolproof, but I would have liked the option of using 24v, rather than just 12 (but the hot bed came pre-soldered for 12v and would need some disassembly to fix - everything is kapton-taped together underneath, with a layer of insulating material beneath the heater) and the 2.5mm alloy plate could easily have been 5mm at little additional cost. It’s just too light, in my opinion.

Overall, not too much to fault. If you are looking for a cheap printer for your mate to get into 3D printing, at $270 it was a bargain, even given its flaws. If you want a little workhorse to take up some of the slack its value for money, but I will be cnc’ing some parts not too far down the line to beef up some areas (and fix that annoying breakage).

Would I recommend? It depends who you are and where you live. If you are in the U.S., probably not- for $100 more you can get better, but for those of us for whom US shipping rates are exorbitant, it’s not a bad job for the money…if you are adept and with a bit of experience. I wouldn’t recommend it for a beginner.