Builders/Lasercut Hints

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Revision as of 21:51, 18 December 2008 by RussNelson (talk | contribs) (fixed a few spelling misteaks and added a couple of hints.)
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Tips to remember before starting

Keep all the bits

Ian has done a good job of getting the most out of the plastic. Unfortunately some bits that look like they should be thrown away are actually required. Personally I had a special reprap bin which had all the offcuts in it. So far I have gone through it about three times looking for missing parts. Fortunately they were all there safely in the bin.

Accuracy

It is tempting to go for "good enough" when it comes to accuracy on your first build. But getting it right first time saves a lot of time in the long run as the reprap simply will not work if it is out of alignment. (especially the Z axis) you will be faced with the soul destroying prospect of pulling it all apart to get it done right.

Over tightening

Careful when tightening any screws or bolts, Acrylic does not show stress very well. Resist the urge to give it one more turn. Remember if it is tight enough to hold the parts in place there no need to go any further. You also can always come back and re-tighten something if it comes loose. A small acrylic spanner is included in the current 3mm sheet; it is more than sufficiently strong to crack the acrylic parts!

Fixing Cracked parts

If you do happen to over-tighten a piece and it cracks do not worry too much.

  • First make sure you have all of the broken bits.
  • Test your glue. If you bought the kit from Ian use some of the scrap border pieces to test your glue. Some super glues will work on Acrylic. Let the test part sit for several hours to make sure it really holds.If you want to make sure it works. Use an acrylic solvent such as "Plastic Weld" Or "Weld-on 4". (Most acrylic solvents do contain hazardous chemicals so use gloves and in well ventilated areas.)
  • Carefully glue one piece at a time. Hold the glue piece in for at least 30 second with light pressure. Let it dry/cure for a few minutes before gluing another piece.
  • Let the now fixed part dry completely. Read the label for the curing time (usually 24-36 hours)
  • I know you may want to rush this part but it is better to take your time and do it right once rather than have to redo it several times.

Lowering The Cost

You can reduce the cost of the Ponoko RepRap by cutting the MDF bed on cardboard as a template, then hacking your own out of your preferred bed material. This is also useful if you want to experiment with alternative bed materials.

Ordering from Ponoko

Ponoko should be offering pre-configured packages in the near future, but in the meantime you'll have to register, download the designs yourself from here, and upload them back to Ponoko in MyPonoko Account -> My Designs -> Add a new design. The following material configurations should be used:

  • 5mm-laser-acrylic.eps: Acrylic plastic, 4.5mm thickness, 790.0 mm x 384.0 mm sheet size
  • p2-3mm-parts.eps: Acrylic plastic, 3.0mm thickness, 384.0 mm x 384.0 mm sheet size
  • p3-bfb-extruder-beds.eps: Acrylic plastic, 8.0mm thickness, 790.0 mm x 384.0 mm sheet size

Note that clear acrylic may aid assembly, and not all colors are available in the needed thicknesses. Using clear acrylic and without shipping, this currently costs USD$385.41. If you get hold of Vik he can arrange a discount on the cutting.

Checking the rods for straightness

You should verify that your 500mm rods are straight. If they're not, you will be very unhappy. On a flag surface, lay two rods parallel about 400mm apart. Place the rod you are checking between those two rods. Take a fourth rod, and lay it on top of the rod being checked, parallel to the two rods. Use it to roll the rod back and forth. If the rod is not straight it will not roll smoothly. Bend it gently until it is straight.

English vs. (American)

  • grub screw (setscrew)
  • studding (allthread)

Grubs and nuts

The grub screws don't really want to stay in place. You may wish to use a touch of hot-melt glue to hold them while you manipulate everything else.