From NC Pro to 3D Printer Novice

by Siemens Valued Contributor Siemens Valued Contributor on ‎03-09-2015 08:00 AM - edited (2,267 Views)

I am a machinist and CNC Programmer, and I like to refer to myself a “CAMologist”.  My entire professional career has revolved around subtractive processes.  I don’t use the word “expert” lightly, but if I don’t know what I’m doing in the CAM field by now, I never will.

 

When it comes to 3D Printing, I am a complete and utter novice.  3D Printing is beyond buzzword right now.  It is a white hot field with lots of people advancing the technology.  From 3D printed prosthetics to 3D printed houses to 3D printed metal nozzles to 3D printed wrenches in space to 3D printed cars, this technology is being applied everywhere.

 

The 3D printed car was done by Siemens partner Local Motors at the 2014 International Machine Tool Show (IMTS).  I was at that show, and another 3D printer manufacturer caught my eye there.  AirWolf 3D makes several different 3D printer models, and they feature larger-than-average print volumes.  I have a curiosity about 3D printing, they have 3D printers; let’s get together!

 

Mark Burhop first got me intereseted in 3D Printing back in 2012 when he made these desktop trinkets for Solid Edge University 2012.  Since then, I have been to Maker Faires and other events where 3D printers are in use.

 

Most CAM packages have a cutting technology that is very similar to how 3D printing works.  In NX CAM, it is called Z-Level Milling.  Other systems refer to it as Waterline Machining.  At each cut level, a plane is passed through the solid body.  The intersection curves between the solid and the plane represent the Cut Area for that level.  The main difference between the two technologies is that in machining we are removing material to get to that shape, and 3D Printing is adding material to get to that shape.  Another difference is Z-Level milling starts at the top and goes down, while 3D Printing starts at the bottom and moves up.

 

Can you teach an old dog new tricks?  I plan to find out by educating myself on 3D printing. I have ordered an model HD printer and I will use it to teach myself about the technology. As I learn, I will post my progress here.  In the meantime, if you have questions about 3D printing, post them in the comments below, and I will try to find the answers as I learn about this exciting technology.  Here is a list of some of the questions I have right now:

  • Why is a heated bed important for printing plastics?
  • Why a glass bed?
  • Is there a way to get rid of the visible lines from each layer of deposition?
  • Does the 3D printed object shrink as it cools?
  • Is there a way to incorporate inserts (like a threaded hole made from metal) in my 3D print?
  • How can I 3D print an overhang (“undercut” in NC Machining terms)?

 

I also have a couple of ideas for projects to print, but I am open to your suggestions also.  Stay tuned!

 

About the Author

 

 

Jim Wright has a Master’s degree in Business Administration from the University of Central Missouri. He has over 30 years of experience in the manufacturing industry, and over 25 years of experience in the CAD/CAM field. He supports Siemens PLM CAM products. Prior to his current role, he held stints as CNC Programmer, Project Coordinator, CAD/CAM Department Manager, and CAD/CAM instructor for Siemens PLM. 

Comments
by Esteemed Contributor
on ‎03-09-2015 01:35 PM

Jim, a lot of this depends on the method and capability of the 3D printer.  You are apparently talking about a fused deposition modeler using a plastic filament.

 

The plastic is heated to the point where it becomes extrudable and is sticky.  I always assumed that  the build platform and often the entire build envelope is kept warm so that the already deposited layers remain sticky and good layer to layer adhesion occurs.  I also assumed that this aided in dimensional stability because plastic does shrink as it cools.  Can't say why a glass platen is desireable...

 

To get rid of the lines between the layers, sanding and often solvent polishing is used (light brushing of a solvent to slightly melt the surface helps erase the lines and improve layer to layer bonding).

 

Don't know of any way to add inserts during the modeling process.

 

Overhung parts are really difficult with hobby modelers as the often don't incorporate a support solution for this like production systems do (Stratasys) with break away or disolvable support material.  Of course if you use a sintering based system, the powdered material provides the support but I haven't seen any of those at the hobby level yet.

by Phenom
‎03-12-2015 08:09 AM - edited ‎03-12-2015 08:16 AM

Other than lowering layer thickness as much as possible, an acetone vapor bath, using a container and a hot plate, is a good way of smoothing the print and getting rid of layer lines- which become worse with detail geometry on your print that is close to the same plane as the layer deposition.

 

The angle of overhang printing you can actually get to before using support material is rather impressive to me. This is an area where clever modeling techniques and careful part orientation will reap benefits to your print time and quality.

 

Using ABS filament, which melts at a higher temperature than PLA filament, requires a heated build plate and heated enclosure to prevent warping of prints and separation from the build plate due to uneven cooling.

 

Using a glass build plate is a good way to ensure a build plate will stay level and flat, heat very evenly, and be easy to clean.

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