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It was great fun to play with, and a complete bargain, but let down by considerable slop and flex in its components, which must be much worse in the larger more popular 3018 version that uses the same components, but with much far longer guide rods.
I thought things could be improved with a few cheap components and some 3d printed parts, and drew the diagram on the left soon after I got it.
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Little did I know how much design time was required, and what a learning curve there was to climb.
3d printing has a lot of limitations (that have emerged over many many prototypes), particularly when it comes to lining up multiple bearings with sufficient accuracy for them to work smoothly – I am so impressed with the accuracy of even cheap bearings.
Plus, 3d prints in normal materials (PLA, PETg) are never going to be as rigid as the glass-reinforced injection moulded plastic in the original, let alone be as rigid as aluminium.
Anyway, following a concerted push, here is the part-completed 1610amateur (right).
It has a single 80 x 20 extrusion across the back of the z-axis (cut by Ooznest – and excellent service in the UK) instead of two 20×20 extrusions, re-positioned so the centre of the extrusion aligns with the leadscrew and so that the spindle motor (the cutting motor) does not need to hang out so far in front of the z-assembly.
The repositioning required for my version was 10.0mm forward and 10.0mm down – I notice not all similar mini-CNCs have the same side-plate hole juxtapositions – for example: 68 or 72mm intra-rod spacing.
Linear rails (cheap 3d printer spares) are used on the new extrusion instead of rods for x-axis guidance and support – this works very well once they are laboriously aligned – no noticeable flex or slop anymore and a lovely smooth action.
Belt drive has been adopted for the x-axis leadscrew, allowing proper thrust bearings to be installed.
Just assembled and not optimised, backlash (zero force) is down to 35μm in the x-direction (left-right) and 15μm in the y-direction (fore-aft) – which had ~160μm or ~80μm – although there is at least ±50μm of flex on top of this if you push things firmly with fingers – not bad though for a few quid in components (and a lot of time…).
Much of the backlash reduction is down to moving away from the supplied spring-loaded anti-backlash nuts and adopting fully constrained anti-backlash nuts – essentially replacing the spring with a pair of (very) carefully-adjusted screws. The current ones are 3d-printed PLA, brass should get ti below 10μm with less elasticity.
And a note to many pundits on the Internet: adding stronger and stronger springs to the original assemblies is only going to get you so far…
The prototype z-axis (up-down) for my ‘improved’ 1610 can be found here (image left) – it is very difficult to get smooth motion on paired linear rails mounted to a 3d-printed plate, it turns out….. At least when I do it.
Simple improvement for the original 1610Pro:
Something I have discovered about the original 1610Pro is that the 10mm diameter linear rods tend to be cut a little short – which is good as they will fit in, but the plastic (described as Bakelite’) end-plates and side plates distort if all the bolts are done up tight. And they need to be done up tight as they contribute to frame rigidity.
M5 shim washers are cheap (I bought a few of each 0.1, 0.3 and 0.5mm types), and they can be used to carefully pack-out the ends of the 10mm smooth rods, allowing all of the bolts to be fully tightened for rigidity, without distorting the frame.
Something impressive about the original 1610Pro (image repeated right) is that the z-axis guide rods (the vertical ones by the cutting motor) and associated mounts and linear bearings fit perfectly in the unit I have, and have a very smooth action – if I could have kept that, I would have done.
That said, one of the bearings keeps sliding out of the housing – a little tighter fit would help.
These are let down in my version by the horizontal (z-axis) linear bearings in the same assembly which are a sloppy fit on the 10mm z-rails (not awful though) and sloppy in their holes. The grey plastic parts (which I believe are glass-reinforced plastic) are pretty rigid.
