On 8/15/14, 10:02 AM, Dave M wrote:
ChesterW wrote:
On 8/14/14, 1:51 PM, Dave M wrote:
I'm starting to get interested in 3D printing. My primary purpose
would be to make parts for obsolete equipment, and other parts that
are no longer available. These parts often have imbedded metal
parts, such as a metal ferrule inside a knob, or an imbedded nut or
mounting tab. Can 3D printers make such parts? If so, is any additional
equipment
or unique model of 3D printers required?

Monoprice has a model that appears to be a clone of a Makerbot
printer at about half the price. Reviews seem to indicate that it
is an excellent printer, although not perfect. I guess that 3D
printers are relatively new on the scene, and will improve in time.

Thanks for any insight,
Dave M


Hi Dave,

If you want to get your own 3D printer and make custom parts I can
think of 3 things you'll need:

First is a 3D drafting package, something that will make a .stl file
(stereo lithography file).

Snip

Second is a program to prepare the .stl file for printing. These
programs are commonly called slicers.

Snip

Third is a printer. One decision you need to make is material type.
The two main choices for the class of printers you are considering is
PLA (a hard, biodegradable, brittle plastic) and ABS.

Snip

There are many types of professional 3D printers. They come closest to
turn-key what-you-draw-is-what-you-get operation. There are many
services that will print your parts for a fee and have available
printers of various capabilities. Materials for these printers cover a
wide range from fused plastic powders to stainless steel. Most
companies use printing supplies as profit centers and so even after
purchasing, printing supplies can cost you. Using a professional
service is the surest way to get parts that are exactly as you've
drawn the first try.

Snip

To sum up, I think these printers can be a useful tool for
prototyping, making jigs and even for short run production,
especially for internal brackets that don't need the strength of
metal and where surface finish is not important. The home-class
machines require a large investment of time but not a lot of cash.
The professional printing services are the best bet if you need only
a very occasional part or if you have a reasonable budget for parts.
I might compare using the home-class machines to making pcbs at home
vs using a professional service, say 20 years ago.

ChesterW

Thanks for your input, Chester
I'm well aware of the software and 3D modeling requirements in order to even
begin to make a 3D printer work. I've a number of years experience using
and supporting CAD modeling systems, although it's been several years ago.
And I know that the parts produced aren't perfect, but they can make parts
that would otherwise be very to duplicate by other means.
As you infer, learning more about the types of plastics that these things
can handle is very necessary.

I'd like to see one in action, and get more info on what they can (and
can't) do. Right now, as I said in my original post, it's an interest, not
something that I have my heart set on doing.
Other types of manufacturing have been proven to be cost-effective for
hobbyists, such as vacuum forming, and machining, but each process has its
own set of pros and cons, as does 3D printing.
I think my next move is going to be to find a company that will make parts
for me. I didn't know that these these services exist. Do you have any
recommendations?

Many thanks for all the input from the others who have responded.

Dave M


Dear Dave,

There are many videos on youtube of these type printers working that
might interest you. There are also many service companies. Search for 3D
printing service and you'll be inundated. If you want an inexpensive
sample of printing from a modest machine, see ebay - some people are
using these to make gee-gaws to sell.

Here's a close-up of the print nozzle for a Makerbot Replicator 1 with a
mm scale:

http://tinyurl.com/lwq74zu

and here's a photo of a part with a melted-in brass insert:

http://tinyurl.com/kvqdav7

A couple of other mods, besides those I previously listed, needed to get
my printer somewhat reliable were a foil shield to block the extruder
fans from cooling the part and replacing the plastic build plate arms
with machined aluminum arms.

Someone mentioned the possibility of removing a part from the build
plate and then precisely replacing it to continue the build. I wouldn't
say it's impossible, especially since someone here would then do it, but
it would be very impractical. The part is basically melted onto the
build plate as the first layer is printed, and this adhesion keeps the
part registered during the build. Loss of adhesion is a major cause of
failed builds.

Some printers offer the option to pause in mid-build and then re-start.
The feature is intended to allow you to change filament, say to a
different color. It might be possible to get close to what you want
using a pause as long as you don't remove the part from the build plate.
You'd need to make sure that any metal you placed did not extend above
the previously printed surface - else your print head will crash into
the metal. Another way to embed metal might be to print the part in two
halves, place the metal piece, and then glue the halves together.

I think machines like the Makerbot can produce reasonable results, but
you pay with your time. You can even get nice prototype cases if you are
willing to do some filling, sanding and painting. Alternatively you can
get pretty and reliable prints from a service or by purchasing a $20k
Stratasys machine, then you pay with your wallet.

ChesterW