IR sensor and fan discovery

I decided to print out some new parts in ABS and did a partial re-work of my Ormerod this morning. New X-carriage, Z-slider and hotend parts. Everything is a lot tighter and more stable, and runs far more smoothly, and I no longer need tape on the Z extrusion or a hacksaw blade on the X extrusion (though I am using a 10mm bearing on the X carriage). Lubricated the Zscrew and runners with 3-in-1. Two things I noticed:

1) The fan would not turn at first (seized) - it turns out that if the two mounting screws are tight, it distorts the fan frame and the blades make contact. I had to slacken off the two screws - which means the cooling block is not held as tightly as I would like to the heatsink, as it uses the same two bolts to press them together.

2) All my Z-probe readings are way lower. My calibration reading used to be 690 at 2.5mm. Now it is 260 at 1mm ! Actually this is much better, because the fast-changing region is closer to the bed, and also it appears to be far less influenced by ambient light.

There is a very good reason for that change - I printed my new X-carriage in black ABS. It all makes sense - the photocell is now far better protected from ambient light and reflections from anywhere except straight down. I doubt many people will want to print out a new part in black, but perhaps a bit of black paint inside the probe recess would achieve the same thing.

Dave

Edited 1 time(s). Last edit at 01/10/2014 11:38AM by dmould.

Hi Dave

Interesting about the sensor readings, but it makes sense. Perhaps red, slightly opaque, plastic surrounding the sensor wasn't the best choice... We haven't noticed any particular problems with the green-plastic printers. We have quite a few other colours to try - I want a grey Ormerod! Any chance of a picture of your new printer?!

Ian
RepRapPro tech support

Still cannot insert photos(the "create link in message") does nothing for me, but some images attached.

Dave