Raptosaur – my new large format 3-D printer


I’ve been finishing my new 3-D printer.

2014-10-29 17.58.07

A view Inside the enormous print area.

A view Inside the enormous print area.

Here is a link to a video of one of it’s first prints: Raptosaur.

I was printing a leopard seal skull from at 30% scale, at the Mini Makerfaire at Vocademy in Riverside CA.  When it’s calibrated I will be able to print this full scale.  I want to provide full size fossil and animal skulls to local schools.

The features of this printer:

  • Large printing area: 14″ diameter (or as wide as 17″) by 24″ tall
  • Temperature controlled build chamber to allow building big without shrinkage problems
  • Double pane Lexan window
  • Magnetic ball joints for low friction no-lash movement
  • Carbon fiber rods
  • High temperature neodymium magnets in the carbon fiber rods attach them to the ball joints
  • Heated build plate made from cast aluminum tooling plate
  • High resolution (400 step), high torque Nema 23 stepper motors
  • Custom direct-drive Bowden Extruder (using the same model stepper)
  • Custom Hot-End using coaxial cooling (details in another post)
  • The case is built using 3/4″ MDO plywood
  • A Rumba controller (for now)

In the video I had just gotten the printer working, with a few bugs to iron out.  Since then I have:

  • Adjusted the accelerations to fix problems with missing steps.
  • Ground flats on the stepper motor shafts to keep the pulleys from slipping
  • Printed stronger parts for the extruder tension leaver
  • Printed a new effector assembly and bearing brackets for stronger support of the ball bearings
  • Upgraded to the latest Repetier firmware.
  • Switched from Cura to Slic3r.
  • Built new 1/2″ solid steel stepper motor mounts – these are much quieter!  We built these at Vocademy.

Still to do:

  • Build a mini Hall effect sensor for bed probing (doing this now)
  • Build the power supply board for the heated bed (also in progress)
  • Finish other calibrations – retraction, extrusion amount
  • Assemble the new effector assembly with better attachment for the 1/2″ bearings (and will use a better adhesive)
  • Fan speed controllers
  • Control panel
  • Upper surround
  • 2014-11-10 10.42.56 HDR

    The tiny board is the hall-effect sensor board for the bed-probe (for auto leveling). The blue bards are for the heated bed power supply.

So much to do… I will update this in a bit.

Creating a Thermal Cycling Rig for Testing Copper Via Rivets

I am creating a rig to test the reliability of Copper Via Rivets. IN PROGRESS..

Latest Update: I’ve re-done the temp sensors using cat-6 twisted pair cable and some other components.  When I can I’ll post pictures.

Update:  I’ve been having problems with the temp sensors reading unreliably.  I’ve tried several things to fix this, but really I have been trying to fix it blind, which is a bit of a pain and somewhat discouraging.  What I really needed was an oscilloscope to be able to really see what’s happening.  The one I found was about $355 on Amazon: Rigol DS1052E 50MHz DSO

Product Image

I found another site where I could order it with free shipping for $336. It only took 10 days to receive the scope shipped from Hong Kong to near Los Angeles, from  Their standard shipping included a USPS tracking number that worked fine.  I’m impressed with it.  The only issue was they sent it with a “China standard” plug… but the socket on the side of the scope takes a standard computer cord… no problem.

The interesting thing about this scope is that it can be switched to a 100 mhz scope by changing it’s model number etc using the USB port – the same hardware was used for both models!  I’ve done it, no problem. This blog tells how.

This project will now continue, since I’ve figured a way out of my dilemma.  I need to re-make the test board, and test a slight improvement in riveting while I’m waiting for the scope to arrive.

Update: I found some interesting information on the causes of thermal cycling induced failures in industry standard plated vias. According to this article the failure is due to weakness in the plated via wall, and that strengthening the via wall can eliminate the failures and can constrain the relatively weak expansion forces of the laminate. We will see if copper rivets will also behave as stronger vias (being many times stronger since they are solid).

Purpose: to determine if copper via rivets will fail due to thermal cycling.  Assembly and programming are complete, and the test board is complete.  Continue reading

Test Rig Display

Double Sided Test Board ready to etch. This board will have 100 riveted vias in series.

Finished Test Board

Alibre Design – a Great Parametric CAD program

I love this program!  After looking at many different CAD packages I decided on Alibre Design over a year ago – the Personal Edition was $100 then, and it’s more now.

It has a very good sketch mode with parametric dimensioning that stays intimately connected to each object, and you can re-dimension at will. It was a bit of a learning curve, but there are a lot of vids that help a lot, and its well worth the time.

Read More…

You Can Get Your Glasses Online and Save Big Bucks

I recently needed to replace my glasses and found there is a massive markup for glasses frames and lenses.   How much do you think?  100%, 200%?  How about 1000%!!

I found you can order good glasses online with your prescription for as little as $16 or less with shipping.  Yes, it takes about two weeks to receive them, fine!  The usual markup on anti-reflective coating is just as bad, it cost me $50 from my optometrist last time, but costs only $5.00 online.   I was shocked!   Read more…

DIY Riveted Vias

I have developed a method for easily and cheaply creating riveted Vias for circuit boards.

  • A Via is a connection that goes from one side of a PCB to the other.  There are times that you want to electrically or thermally connect the two sides of a board, and a regular commercial or soldered Via will not work – for instance a via in a home-made board may be under a chip and must be flush, or one is in a SMT pad and you don’t want the solder to wick down a via hole, or the via may need better thermal or current carrying capabilities.  Here is the full article, now updated with more photos.

Update: I am building a test board with 100 vias in series, and a Themal Cycling Test Rig to determine if thermal cycling will cause failures in these kind of copper via rivets in FR4.  See above.


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