Saturday 19 April 2014

SLA 3D Printer Project Log 6: Quick Snippet

Since the last post, I have been giving thought to my projector mount - long story short, I believe it will be too flimsy with all that weight resting on an 8mm thread (wrt the vertical adjustment).  As a small update while I figure out what to do from here, I have some basic drawings to clue you in on some ideas for two of the Sub-Assemblies:

I don't draw so well...  I'm not the best calligrapher either...
I have now opted for a tighter design utilizing 3D Printed clamps on the 8mm Steel Rods; I can now drastically reduce the distance, and hence the moment arm the projector will enact upon the structure, enabling a smaller frame overall.

Never one for freehand...
This is an initial design for my Build Platform, consisting of a suspended steel grate (a fine pattern to help grip the print) suspended from four LM8UU linear bearings to stabilise the platform, taking moment stresses off of the 8mm threaded rod, which in turn positions the platform.  I have literally just thought of using two motors like the Reprap as long as I can overcome synchronicity issues.

Another thing of note is that I managed to make the Resin Basin in around 30 mins in Creo:
...Which is why I'm a CAD man ;)
So, not a complicated job, simply laser cut from 12mm cast acrylic to allow the use of heavy duty cleaning agents (Extruded Acrylic has microscopic stress marks which the agents can penetrate and cause further damage); the holes in the end and the bottom (not the flanges, I'll cover them later) are sized to take G 1/4" threads commonly used in PC Water Cooling equipment, the one in the bottom drains the tank of all fluids while the side holes act as fill levels for the Salt Water and the Resin on top - Procedure for filling is as follows:

  1. Close the Bottom Valve.
  2. Open the Lower Side Valve (the Upper Side Port will have no valve).
  3. Fill the tank with Salt Water until it flows out the Lower Side Port.
  4. Close the Lower Side Valve.
  5. Fill with resin until it flows out of the Upper Side Port.
A similar procedure is done for draining:
  1. Remove any Prints.
  2. Open the Lower Side Valve.
  3. Let The remaining Resin drain out.
  4. Open the Bottom Valve.
  5. Let the Salt Water drain out.
All fill leveling is therefore done by the tank if the correct procedure is followed, I have it calibrated for 20mm of Resin on top of 110mm of Salt Water, giving 120mm of Z axis Build Area alongside a proposed upgrade of 192mm x 108mm build area once I source a 1080p native projector (once I've sifted through all them "1080p" projectors with an embarrassing native resolution of 800 x 600 >:(  ) .

The other holes on the flanges are simply mounting holes to suit M10 bolts, and another idea as of present is to make a calibration sheet from more 12mm Acrylic set to the same height as the resin to position the projector accurately.  I propose using L plates for accurate positioning of the basin.

Take care :)

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