Four Conductor Sliding Ring

Show off your prints!!!
User avatar
pyronaught
Posts: 684
Joined: Mon Dec 01, 2014 8:24 pm

Four Conductor Sliding Ring

Post by pyronaught » Fri Feb 12, 2016 3:30 am

After a few years of dealing with my CNC heat wheel strangling itself with the power cord, I finally got around to designing a set of sliding contacts for it so that it can spin infinitely in either direction with no worry of cord strangulation. Just in time too, the insulation on the old one was just about worn through and ready to short the 120v line to the heating element. Since the wires don't move on this new one, there is nothing rubbing on the insulation to cause that problem. The fixture for holding the 28mm rotary cutting wheel on the other tool head is also 3D printed.

The hard part here was making the set of four concentric copper rings. I bet ednisley can figure out how I did that.
006.JPG

https://youtu.be/PE_zWWf4nv8
Experience is what you get when you didn't get what you wanted.

User avatar
jimc
Posts: 2888
Joined: Wed Apr 09, 2014 11:30 pm
Location: mullica, nj
Contact:

Re: Four Conductor Sliding Ring

Post by jimc » Fri Feb 12, 2016 5:09 am

nice! what did you use for the contacts? some type of carbon brushes?

User avatar
ednisley
Posts: 1069
Joined: Fri Apr 11, 2014 5:34 pm
Location: Halfway up the Hudson
Contact:

Re: Four Conductor Sliding Ring

Post by ednisley » Fri Feb 12, 2016 1:20 pm

pyronaught wrote:figure out how I did that
Mmmm, I'd start by mining copper ore... [sigh]

Etching copper is much safer than machining it: that stuff will grab a cutter and fling itself across the shop with no warning. Been there, done that, wrecked some nice stock, won't get fooled again.

You obviously enjoyed plenty of Quality Shop Time making that tool!

User avatar
pyronaught
Posts: 684
Joined: Mon Dec 01, 2014 8:24 pm

Re: Four Conductor Sliding Ring

Post by pyronaught » Sun Feb 14, 2016 12:12 am

ednisley wrote:
pyronaught wrote:figure out how I did that
Mmmm, I'd start by mining copper ore... [sigh]

Etching copper is much safer than machining it: that stuff will grab a cutter and fling itself across the shop with no warning. Been there, done that, wrecked some nice stock, won't get fooled again.

You obviously enjoyed plenty of Quality Shop Time making that tool!

Yes, in one of my attempts I epoxied a sheet of .1" copper onto a 3D printed backer, then chucked it up in a lathe with the intent of turning grooves to make separate rings. The cutter grabbed and ripped the sheet off, and also I think the heat generated weakened the epoxy as well.

So etching the rings with acid was the way to go. I still had problems masking the copper well enough to keep some acid from getting through over the long duration the etching took to get all the way through the sheet. My first attempt was the laser printer toner transfer method, but the coating that produces had pin holes that resulted in a pitted surface on the rings. I tried the Sharpie permanent marker method too, but same problem. The winning solution was to just spray paint both sides of the copper, then drill a center point and use a compass scribe to scrape circles through the paint to expose the copper where the rings needed to be separated. Once the rings separated in the acid bath they were then etched a little longer until the gap between them was about 1/16". Acetone was used to remove the paint once the etching was complete. The connecting wires were then soldered to each ring on the back side prior to epoxying them into tracks on the printed base. Another printed fixture jig was used to press the rings and sandwich them using a set of clamps.
Experience is what you get when you didn't get what you wanted.

User avatar
pyronaught
Posts: 684
Joined: Mon Dec 01, 2014 8:24 pm

Re: Four Conductor Sliding Ring

Post by pyronaught » Sun Feb 14, 2016 12:21 am

jimc wrote:nice! what did you use for the contacts? some type of carbon brushes?
Spring loaded test pins that are normally used for circuit board testing fixtures. They are tiny and can fit side by side on a short arm, yet still rated for up to 15 amps.
Experience is what you get when you didn't get what you wanted.

User avatar
insta
Posts: 2000
Joined: Tue Sep 16, 2014 3:59 am

Re: Four Conductor Sliding Ring

Post by insta » Sun Feb 14, 2016 2:46 am

pyronaught wrote: The hard part here was making the set of four concentric copper rings. I bet ednisley can figure out how I did that.
I'm not ed, but I was going to guess witchcraft and goats blood.
Custom 3D printing for you or your business -- quote [at] pingring.org

User avatar
ednisley
Posts: 1069
Joined: Fri Apr 11, 2014 5:34 pm
Location: Halfway up the Hudson
Contact:

Re: Four Conductor Sliding Ring

Post by ednisley » Sun Feb 14, 2016 3:39 pm

insta wrote:witchcraft and goats blood
Propitiating the Machine Shop God begins with an offering of your blood.

Around here, bleeding for 3D printing requires weapons-grade stupidity ...

User avatar
insta
Posts: 2000
Joined: Tue Sep 16, 2014 3:59 am

Re: Four Conductor Sliding Ring

Post by insta » Sun Feb 14, 2016 8:19 pm

I resemble that remark. :evil:
Custom 3D printing for you or your business -- quote [at] pingring.org

User avatar
ednisley
Posts: 1069
Joined: Fri Apr 11, 2014 5:34 pm
Location: Halfway up the Hudson
Contact:

Re: Four Conductor Sliding Ring

Post by ednisley » Sun Feb 14, 2016 8:42 pm

I absolutely hate seeing blood all over my fingers and having no idea what sliced me: that razor-sharp metal remains perfectly clean.

Today's projects include rebuilding a brace of fluorescent shop lights with LED tubes; those fixtures have nasty edges. I want vengeance and I want it now!

Gimme some good 3D printing action any time...

User avatar
pyronaught
Posts: 684
Joined: Mon Dec 01, 2014 8:24 pm

Re: Four Conductor Sliding Ring

Post by pyronaught » Mon Feb 15, 2016 8:28 am

I got a bunch of nasty cuts lifting the melamine boards for making my 3D printer cabinets. Thin little chips of the plastic coating on those things overhangs the edges by a tiny amount and are razor sharp. You would think the factory saw would produce a clean edge, but for whatever reason it doesn't. I still have to wash the blood stains off.
Experience is what you get when you didn't get what you wanted.

Post Reply