Tuesday, February 5, 2013

More Valves

I've been doing quite a bit of parts with Shapeways lately both flow models and functional parts.   One of the latest is a rework of my servo actuated plug valve.

Two parts allow a Swage-Lok SS-4P4T valve to be actuated by a Hitec servo - I recommend a high torque metal gear model like the HS-7954SH.   The only other hardware required are (you'll need taps to clean up the threads in the nylon):

qty 4     8-32 x 5/16" Socket Head Cap Screws, McMaster-Carr 92196A191
qty 2     4-40 x 1.25" Socket Head Cap Screws, McMaster-Carr 92196A302

The printed parts are available on Shapeways

Shaft: http://www.shapeways.com/model/903741/shaft-coupler-hitec.html?li=productBox-search
Bracket: http://www.shapeways.com/model/903740/bonnet-ss-4p4t.html?li=productBox-search


RS4H said...

Very interesting design. How does this compare to your earlier design, in terms of weight, volume?
Have you considered Heli-coil threads to allow stronger threaded connections?

Really appreciate the open approach you take to your work here, very interesting.

Rocket Dude said...

The weight is 3 grams lighter for the nylon version. The physical envelop is the same. For lots of 10 or less, the price is much cheaper than the aluminum version, primarily because there are fewer "McMaster-Carr" parts.

In regards to helicoils, I find the nylon to be strong enough for this purpose and I don't really think helicoils are necessary. The bracket is much stiffer than I had anticipated - I think the design should have good durability for long-term use applications.

gnsortino said...

Thank you for posting these details. This is extremely useful.

I just purchased the raw parts for this and had a few questions about how to best mate the shaft coupler with the valve and servo.

1. When the shaft coupler part arrived from Shapeways the grooves on the servo coupler were a bit smoother than I’d have liked and they did not seem well defined enough to mate with the servo. Is there a technique you’d recommend for cleaning this up? I was worried that forcing the coupler to mate with the servo would strip off the plastic.
2. From looking at the picture it appears that the plastic handle from the plug-valve was removed in order for the coupler to mate with the valve. Is this correct and do you have any advice for how best to remove the valve handle?
Thank you again very much

Rocket Dude said...

1. The splines are sizes a little bit under. I lined them up and pushed onto the the metal shaft on the servo to full form the grooves on the nylon. It won't work for an infinite number of mate/demates but its been working fine for me.

2. The handle has a pin that holds it to the shaft. Just push the pin out and the handle comes off. Reuse the pin to attach the shaft coupler to the valve.

Rakesh Roshan said...

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