I Love 3D – Part 2

Friday, May 24th, 2013

Part 2 – Applications:

Before we get to the fun stuff… It’s important to point out the way in which 3D printing works, and the challenges to overcome when designing a part.

First, the printer prints in layers, and that impacts finish and strength. Here is a great picture that shows the same part printed in two different orientations. The one on the left was printed with the largest flat surface (the bottom of the part as shown) against the printer bed. The part on the right was printed standing on its end.

20130529-190850.jpg

Another issue is corner warping… Its one thing to keep the part stuck to the bed during the print… Another thing is keeping it flat and un-warpped. Due to the heat involved in the process, corners of larger parts tend to warp and pull up from the bed.

20130530-150253.jpg

This is challenging to overcome with some parts, especially larger parts with a large surface area touching the bed. One thing I’ve been doing lately is printing a large brim. This is a Slic3r feature… You can turn it on and configure it in the Slic3r configuration screen. I print a 12mm brim and that seems to help.

20130529-194557.jpg

That said, these printers (yes, I own two now) have opened up so many possibilities. Parts that I’ve wanted to make for ages, even ones I had already designed but didn’t start fabricating (due to the time commitment they would require), have been printed in hours as opposed to days.

Example… I’ve wanted for ages to experiment with a larger grip on my Ultra, and now my Ultra2. I’ve always liked the feel of the grip on the MK-V, XCS, etc. I didn’t have a design yet, but said “what the heck.” Let’s see how quickly I can tackle this problem. I took some measurements, opened Solidworks, and spent about an hour drawing the part. The design required two halves that would clamp over my existing handle. So I exported the two halves as STL files, and loaded them into Repetier. You can print multiple parts at the same time, so I positioned them on the bed together and ran Slic3r. Clicked a button and 4 hours later it was finished.

20130529-194816.jpg

I then installed helicoils, clamped it on, and added grip tape that I like. The entire process took about 6 hours (only two of those hours required my involvement). Had I made this part on my lathe and mill… It probably would have taken two days (with me there and present the entire time) assuming no mistakes. And if I got it wrong or wanted to make a tweak I would have been back to square one. Here, if I want to change something I just tweak the model and re-print… And if I need another one, the gcode is saved, so just click print. Here is the finished product… It works great!

20130529-195206.jpg

Another great application is for producing custom connector housings. Have you ever needed to make an adapter for a cable, but one of the connectors had to be a chassis mounted connector? This happened recently just prior to a ZipCam job. We use mil-spec amphenol connectors for our motor cables. I needed to make an adapter, but the female connector was only available in a chassis mounted receptacle. So I simply made a connector housing. Basically, it was a custom project box that came out of the printer with all of the mounting holes and clearance holes for the amphenol connector on one end, and a strain relief clamp and cable pass-thru on the other.

(Picture of amphenol adapter coming soon!)

Speaking of clamps, I have been designing a new mounting bracket for my gyros that incorporates a universal clamp accommodating 15mmx60mm, 19mmx100mm, 0.620×3″, and 0.620×2.5″ rods. This is an example of a part I had designed years ago, but never got around to making. The gyro mounting bracket itself has posed some challenges…but I’ll go into that in Part 3. Interestingly, I experimented with dipping the ends of this part in liquid rubber to see if I could get a better grip on the rails without as much clamping force. It worked great, but made adjusting the position in the clamp on the rails difficult since the clamp didn’t want to slide easily. I may however use this trick again elsewhere!

20130529-202330.jpg

I could go on, and on regarding all the fun and amazing things I made. Like this rose for my wife for Mother’s Day. The flower pot itself printed all as one, and the stem and rose printed as two separate parts that I glued together. The designs for this came off a website called Thingiverse.com which is a free, model sharing website. I love the concept, and I’m sure the selection of models is going to expand very quickly over the coming years!

20130529-195652.jpg

I’d like to finish up though with this more practical set of parts. Several years ago I had made a dovetail plate that slides onto the base of my sled and provides IDX mounting plate. The plate was not wired into anything, although you could use the PTap connector to provide power to devices. Alternatively, it functioned simply for additional bottom weight.

20130529-194319.jpg

I never got around to making more, even though I would have liked to, for a couple reasons. First, dovetails are very hard to machine. They are time consuming to get just right. Second, the clamping system was primitive and needed improvement. In this original design I simply used plastic thumbscrews that were driven directly into the dovetail. They tended to break eventually… It wasn’t pretty.

But now, with the 3D printer, I could easily produce dovetails. Once I got the dimensions correct I could pump them out. And I was able to improve the clamping design. In a matter of a couple days I produced several different plates. One set if plates had mounting holes for both IDX and Gold plates.

20130529-202314.jpg

Another set of plates were shorter and clamped a brass plate between them. On one side is a female dovetail, and on the other a male. This allows stacking. I’ve had this raw brass sitting around for years for this very purpose… And I’m not finally putting it to use.

(Picture of bottom weights coming soon!)

As you can hopefully see by now, the possibilities are endless. The speed in which parts can be produced, tweaked and perfected makes this technology ideal for our industry… And I’m sure it’s impact will be profound. In Part 3 I will discuss more advanced applications such as designing parts to overcome weaknesses in ABS and printed parts in general, rapid prototyping, and casting… Yes, casting!

Leave a Reply

You must be logged in to post a comment.