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So how do we print something?

So we’ve got our printer, we’ve got a load of nice colourful filament, so what are we going to do with it?

The first thing we need to do it to print something.  Anything really, we just want to see for ourselves, what this 3D printing thing is all about.  This may not be your first printer, but indulge me a little.

A successful 3D print really just comes down to a couple of key points.  You want the first layers to stick firmly to the bed and you want the filament to flow smoothly and constantly on demand.

The first is, to be quite honest, a bit tedious but, if you don’t do it, you will probably regret it.  We need to level the bed and set the Z-zero (Z0) height.

So, with our printer connected and powered on, we tell it to send all axis home.  This should be to a position of 0,0,0 (we always give such coordinates in the order of X, Y and Z).  With the bed in this position, we should just be able to fit a piece of paper between the tip of the nozzle and the bed.  If not, adjust the Z Home screw to make sure you can.

Once Home is sorted, then we send the printer to the maximum X extent.  And then, when it’s there, we adjust the bed levelling screw (there should be one in each corner) to make sure that we can still only fit our paper there.  Once that’s done, we go to Y extend and do the same and then send X home (Y is still at maximum) and do the same.  Finally, we go to the centre to make sure that all is still okay.

You may find, half way through the process, that you don’t have enough bed levelling movement to compensate.  In this case, we go back home, adjust Z home down a bit and then correct with the corner screws again.

Once that’s all completed, we need to look to the filament flow.  There are 2 main extruder types (if you have another type, I apologise, but you are probably in the minority).  These are a Wades type extruder, it has a smaller gear on the motor, driving a larger gear with a hobbed bolt (this is a bolt with teeth in the middle).  Or a direct drive extruder.  This has a small hobbed drive gear directly on the motor.

In both cases, there will be an idler bearing that pushes the filament onto the hobbed part on the drive train.  This idler should be adjusted so that the pressure is firm, but not too much.  If you tighten it too much, it will tend to flatten the filament, which will then make it more difficult when it comes to enter the hot end.  On the other hand, if it’s too lose, it won’t provide the pressure needed to make it work as it should

In order to check this, heat the hot end to the working temperature of your filament.  For PLA I normally use about 195 and ABS about 220.  This will vary between manufacturers and even colours, so you will need some trial and error.  Try and extrude 50mm and watch the gears turn.  If they turn but nothing comes out, tighten the idler.  increase it in small increments until the filament comes out smoothly and then I give it an extra 1/2 turn on the screw (this is optional and you may not need it).

Finally, load up something like this 25mm calibration cube, slice and print.

Hopefully it will look as you expect, you will have printed something and you are well on the way to playing with this fantastic new toy.

Next time we’ll look at some open source control software and where to get things to print.

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