Machinist Guys, Whatsit Called?

[monkeyswrench]

No pics, because I don't know what it's called. It's kind of an Acme thread/jack screw kind of deal. The "female" portion has ball bearings instead of threads, and the threaded portion of the screw is more of a ball milled helix type deal. I think they were good for weight and for keeping threads from galling...but don't really know. The only one I have seen in person was a prototyped piece from Vard in Pasadena for some aircraft deal. My Grandpa made it in the 50s. Problem is, my brother has it at his house somewhere...so I can't post a pic. I think it would work for an idea I have, but don't know if my memory misleads me.

 

[TimeBandit]

Mophorn Ball Screw SFU1605 350mm, Ballscrew Kit Anti-Backlash RM1605 350mm Ball Screws + 1 Set BK and BF12 Support Ballnut + Couplers, Ball Screws for CNC Machine: Amazon.com: Industrial & Scientific

I've seen something similar used on a Piper Comanche landing gear transmission.

 

[monkeyswrench]

Mophorn Ball Screw SFU1605 350mm, Ballscrew Kit Anti-Backlash RM1605 350mm Ball Screws + 1 Set BK and BF12 Support Ballnut + Couplers, Ball Screws for CNC Machine: Amazon.com: Industrial & Scientific

I've seen something similar used on a Piper Comanche landing gear transmission.

Yep, that's the thing!

The one that I had seen before was only a 12" threaded section, and a 3" steel base. I grew up seeing it sitting on the mantel at Grandmas house, two angels, like you'd see on candle displays, were on it. When she went into a retirement place, was when we realized it was a machined piece. Oiled it, and the carriage would free spin to the bottom. Grandma had told us it was a prototype for a landing gear piece that Grandpa had made when he was still a machinist. Not knowing much about machining, nor aircraft, I didn't know where to start even looking.

Thank you!

 

[Racey]

Ball screws are normally used on CNC machine axis leads. They have very little backlash, by contrast most manual machines run acme screw leads on their axis. Acme screws are also common on clamps

 

[monkeyswrench]

I am familiar with Acme screws. I have used them for, like you mentioned, clamping setups. Because I don't know how to cut threads, I have become pretty resourceful...I have been known on occasion to pilfer the threaded pieces from scissor jacks and trailer jacks...and maybe a garage door opener

These ball screw assemblies would take less torque to actuate given the same load. Trying to broaden my horizons a bit. Maybe moving up to technology of the middle of last century...I'm kind of on the trailing edge of technology.

 

[gottaminute?]

I am familiar with Acme screws. I have used them for, like you mentioned, clamping setups. Because I don't know how to cut threads, I have become pretty resourceful...I have been known on occasion to pilfer the threaded pieces from scissor jacks and trailer jacks...and maybe a garage door opener

These ball screw assemblies would take less torque to actuate given the same load. Trying to broaden my horizons a bit. Maybe moving up to technology of the middle of last century...I'm kind of on the trailing edge of technology.

just a note.....while you've been told you can't rotate s screw by pushing the nut. ball screws have very low friction and the pressure on the nut will force the incline of the threads to turn the ball screw. using a ball screw and nut to support weight is not a good idea.

 

[monkeyswrench]

just a note.....while you've been told you can't rotate s screw by pushing the nut. ball screws have very low friction and the pressure on the nut will force the incline of the threads to turn the ball screw. using a ball screw and nut to support weight is not a good idea.

The application I'm toying with is more of a linear actuator. The mechanism itself wouldn't be supporting/clamping.