Machine Screw Jack

[HpGERepair]

I am looking for a small hand-operated machine screw jack (or linear actuator) type device. I only need about 6 inches of travel, the unit needs to be compact and able to lift approximately 50 lbs. I know there are a lot of motor driven actuators out there but this needs to be hand-operated. If someone could point me in the right direction it would be appreciated.

 

[MintJulep]

Any motor driven actuator could be equipped with a hand crank instead of the motor.

Depending on your speed and positional accuracy requirements any of the following could work:

Rack and pinion, Acme screw, ball screw, pneumatic or hydraulic cylinder with hand pump, cable, drum and pulley, timing belt.

 

[griffengm]

If you are doing this on the cheap, how about a small automotive scissor jack?

Griffy

 

[IRstuff]

For that matter you can also get a small hydraulic jack.

TTFN

 

[HpGERepair]

The actual application involves a 10in x10in steel plate that is mounted to a universal joint(the steel plate is actually a mounting platform for a radiation detector. The plan is to have two of these machine screw jacks mounted to the plate 90º apart to be able to change the angle of the plate. We need to be able to change the angle of the plate in a reasonably short period of time with minimal effort. We thought a machine screw type jack would work well if we could find one small enough with a reasonable gear ratio (no more than 20 turns for 1 inch of travel). We had thought of using a scissor type jack however a machine screw type jack seems like it would work a little better for us. Thank you for the input so far...I am actually an electronics guy so this is out of my area of expertise.

 

[IRstuff]

Bear in mind that the center of rotation will NOT be through the detector, so any angular change will result in a lateral displacement as well

TTFN

 

[HpGERepair]

We are thinking that we can mount the jack to the plate with some sort of swivel joint to prevent binding...not sure if it will work or not....we are kind of shooting in the dark.

 

[pennpoint]

I am thinking turnbuckle with swivel ball ends.

Best Regards
pennpoint

 

[HpGERepair]

That is an excellent idea, but that may be a little hard on our hands and forearms if we had to make any large adjustments. I suppose we could weld a couple of handles on the side of the turnbuckle to make it easier to turn.

 

[byrdj]

you may want to look at some of the sites recommended for this post thread1083-128803

 

[zekeman]

If you need to control the position of that plate you have three degrees of freedom. Acordingly you would need 3 position devices since a plane ( the 10x10 plate in your case) in space is determined by 3 points.

 

[MintJulep]

Zeke,

Depending on the configuration of the "universal joint" mentioned in the OP's second post, it could serve as the third point.

 

[plasgears]

If you can get your hands on a replacement electric car seat actuator, even a scrap unit, you can hand drive the motor thru a square drive on the free end of the motor.

 

[bugnut]

Have you looked at using standard machinists jacks-available from Starrett-Machinists' Precision Shop Tools
"Little Giant" Jack Screws

No. 190 Series 2 1/4"-3 3/8" (57-85 mm)
No. 191 Series 1 1/2"-2 1/4" (38-57 mm)