RepRapPro recently announced a new, low cost delta type 3d printer they where bringing to market. The Fisher is a small, mostly acrylic and printed PLA delta printer that is designed to print in PLA. When preorders where available they where £199+VAT which was remarkably cheap. They’ve since gone up to £249+VAT.
Delta printers differ from regular 3d printers in that they have a print head that is suspended on a set of rods, which in turn are connected via ball joints to a carriage that just moves up and down. By moving each of the carriages up and down in different patterns the head is made to move inside the plane of the printer. A regular 3D printer has an X,Y and Z carriage which only moves in it’s own dimension. As with anything, each method has its pro’s and con’s, but I have to admit, the delta style is both more compact, and a little more impressive looking.
What you get in the box is a complete set of parts to make the Fisher. The acrylic parts are all laser cut, and the plastic components are all 3d printed. The printed parts are printed very well, needing very little, if any, fettling to make them dimensionally correct. Most of the fettling I had to do was just trimming off that last 0.5mm of brim on the outside of some holes, and tidying up a couple of strings. The instructions are still beta and you sometimes have to make a bit of a logical leap to interpret the text to the picture, but overall the build itself is quite simple. I’d like to cover a couple of places in the instructions that I struggled with though.
Starting out with the frame itself, the only place I messed up here was identifying which way around the bottom plate went. The instructions just give you a picture and tell you to ensure it’s in that orientation without many textual pointers. The thing that should be pointed out is that there are a pair of small (3mm) holes on one edge of the acrylic sheet and these should go on the side with the plate that has the electronics holes (not one of the logos). It’s a bit of a bugger to move stuff around at the end of the process if you miss this! I probably wasted half an hour or so correcting this little mistake. I would also leave the endstops until towards the end of the build. It’s a lot easier to understand where they go once you’ve got the frame together. Just make sure that there is one for every pillar.
The frame constructed
With the effector, make sure you read the instructions twice (at least!) before you put it together. The pictures on the docs aren’t amazing for this step.
For the hotend, the main thing to take in account is that when it says use a 2.5mm drill bit to ream out the PTFE tube, USE A 2.5mm BIT! 2.3mm isn’t big enough unfortunately. I wasted about 3 or 4 hours trying to understand why the hotend wasn’t extruding with this. Very, very aggravating! Goes to highlight the point of reading the instructions thoroughly though.
When you’re making up the arms to hang the effector assembly, I would leave the nylocks a little loose so you can get them over the balls easily. DON’T PUT TOO MUCH PRESSURE ON THE ACRYLIC WHEN YOU ATTACH THESE! I broke 2 sets of arms this way, luckily I was in a fully equipped/stocked Hackspace and had access to a laser cutter and acrylic to replace them! This is why Open Source hardware is awesome 🙂
Once you’ve got to the stage where you’re trying to home the machine, I would trim a bit of the loose bit of the belts off. I found that it occasionally interfered with the carriages reaching the ends.
So after putting it together, what’s it like to work with? Well, it can be run a lot quicker than my TVRRUG Round 2 machine. I’m very uncertain about the Bowden mechanism, but since this is my first one, I’m hoping that will pass. It certainly makes sense to keep the heavy extruder mechanism off the dangling head. The filament feed is a bit of a fiddle to get in with the top on. I might actually design a little thing that goes inside it that encourages the filament into the hole, rather than it being just a small hole in the middle of a bigger hole.
The software on the duet is quite comprehensive. I especially like the way it gives you information on the 3 different ways it estimates print time (by file progression, filament usage and layer time). The facility to write and upload new macros is quite useful as well, though the only one I’ve written so far was to raise the Z 0 point a touch as it was a bit low for my tastes. Uploading gcode files over the web interface is also very easy. Given time I think the main thing I’d improve here is to lay out the jog controls in the same way that pronterface does so it’s a bit more understandable from first view. The current layout works, but makes me think too much.
Complete First Print
In terms of slicing, RepRapPro provide an ini file for Slic3r which seems to work really well. The print quality that comes out of it is good as you can see in the image. The BuildTak bed surface really works remarkably well! I’ve found the best way to remove objects from this is with a palette knife that’s had the edges ground down to wiggle under the print.
It’s quite a nice little printer, all in all. I think the only real changes I would make is to add a bottom acrylic plate to keep the electronics hidden and to change the filament inlet to be some kind of cone or equivalent to help guide the filament into the hole. Now we just need to see how it copes over a few months of heavy printing!