3D printing: Modifying Fabrikator Mini v2 spool holder

I am not quite sure this is the place for 3D printer modifications, but as this seems to work it might as well go here so folk have a chance of finding it by web search.

Scroll down to ‘The fix’ to jump over the explanation

The Malyan M100, aka the Turnigy Fabrikator Mini v2 (fixed right), is a 3d printer with a spool holder problem: standard 200mm filament spools foul the extruder motor.

Left: Gap after fix

This is because the spool holder is simply a square peg sticking out of the back of the unit.

On to this, the central holes of the spool locate – touching on the two square edges.

Variation on spool hole size moves the spool up and down, easily eating up the few mm of space between one of the spool rims and the motor causing a jam straight away, and if this doesn't happen immediately then, during printing, the extruder tugs away at the filament causing the spool to rock on to one of the locating edges, pushing the spool rim into the motor.

My fix locates the spool properly (I claim :), setting a workable spool-motor gap (for 200mm spools) and preventing any rocking that could eat that gap up – and it also adds a round spindle, removing the draggy square edges.

It makes use of a couple of unused holes that the printer has. And it is largely made of aluminium because of the way the idea developed, although I think and all-printed version is possible – see below.

The reason it is made of aluminium is that I started off with the idea of running the spool on skateboard bearings – 608 is the part number, they are 7mm wide, have an 8mm hole and are 22mm diameter on the outside, and everybody uses them for everything because they are cheap and easy to get – I paid £2 for 2x 608-2RS (two rubber seals) in the local skate shop. If you need some for some reason, Type 608-ZZ has two metal shields and might be less draggy, though less waterproof.

I couldn't imagine a printed 100mm long 8mm diameter supporting a 1kg spool, hence a steel or aluminium rod or tube instead.

Thoroughly measuring the back of the printer revealed that the spool could be moved down a bit without obscuring the power switch or fouling the power plug.

The fix

The plate is like this (left)with the rectangular holes clearing the square peg's embossed supports (see photo).

Dimension X was 8.5mm in my case, and Y is 21mm. I am sure 34.5mm could be 35, but 34.5 is what the measurements produced

5 minute epoxy was used to glue the 100mm length of 8mm tubing into the 8mm hole, after ensuring the tube was well engaged and perpendicular to the sheet, and left for 24 hours to make sure the bond didn't fail.

Then, using Design Spark Mechanical, a couple of discs with retaining lips were designed to fit the spool, and printed on the Fabrikator Mini v2.

Infill is 20% and, just because it was easy, four extra holes were added save materials – in this case possibly 16mm dia centred on a 16mm radius.

Notes on The fix

Mounting bolt heads have to be on the inside of the printer because the Z-carriage sweeps past during printing, leaving little room.

In my case, I tapped the holes for 4mm bolts but, on assembly, realised there was room for 4mm nuts on the outside so the holes can be straight through. Two 8mm washers (not shown) on the spindle keep the spool away from the back of the printer, allowing room for the nuts – even with these fittted, the spool is closer to the printer rear than it was with the square peg (making the printer less tippy) as the square peg has little tabs that keep the spool about 10mm clear of the printer rear.

1mm rim is plenty

I thread another couple of washers on the outside and, for want of a more elegant solution, hold it all on with a clothes peg.

An all-printed fix

Knowing that bearings are not needed, I suspect an all-printed version of this fix is possible by making the central spindle (at a wild guess) 20-30mm in diameter and adjusting the centre holes in the disks accordingly.Experts, please comment below if you can help on printed spindle diameter and infill.

This would be more draggy, but my guess is that it would still be fine, and a tiny spot of silicone grease or silicone oil would probably cure that – although don't get silicone lubricant on the filament – if you do, the filament is likely to slip in the extruder, and it if gets onto the extruder wheel it will be a bugger to get off.

The embossed peg mounts built into my printer protruded somewhere between 3.1 and 3.2mm, so the printed back plate would have to clear this, and I am guessing it might have to be a bit thicker for strength – maybe 5mm?

Plus you would have to print a spacing washer to suit the spindle diameter.