Linear actuator to replace Quadralift lead screw assy?

[Grego]

Looking on ebay I see various types of salvaged linear actuators. So far I haven't see the right combination of force and travel but it is all wrapped in one package for between $50-$150. What do you think the head weighs? I lifted it, without the quadralift brackets and motor so I'm guessing 200 lbs. I would probably double that for capacity of the actuator for wear and safety. Mounts similar to a hydraulic cylinder with pivot pins on both ends. I just have to build a couple of pivot points and wire a switch.

These are basically the lead screw assembly in one unit. AC or DC. Reversible motor, gear driven lead screw, limit switches. I've seen capacities up to 1500 lbs. and 4-26" linear travel. I need about 18" for full travel. Retail is about $450 but if I can find a used or overstock unit the prices are more like $150. Something like the unit below.

Anyone use these? Comments?

Grego

[mixdenny]

The assembled milling head without the motor weighs less than 100 lbs, so 200 lbs with the motor and stage is a safe estimate for planning purposes. I remember weighing mine as I was tempted to fill the inside with concrete or lead shot to absorb vibrations better, and I was trying to see what percentage of weight I could gain.

The actuator should work OK, although I haven't seen any reasonably sized ones with an 18" travel. That's an extra long travel, my factory Quadralift only moves 12". The four rods are 20" long, but the stage is 7" thick, and there are bolts heads, etc, so you have to subtract all that in order to see how much net travel you need.

I have purchased actuators at work for various projects, and they should have a safety factor already built in, so you probably don't need to double the rated load unless you are trying for rapid acceleration, which you shouldn't need.

You can try the Surplus Center, they always have a bunch available, although I didn't see anything like the specs you need right now.

http://surpluscenter.com/

Dennis

[Grego]

Another clue regarding whether the lift is home built. My tubes are 26" long so I can get 18" of potential travel. I don't know why I would ever need to raise the head that far and how stable it would be but I've got overhead clearance so I'll leave the tubes long.

I was tempted to get a shorter actuator and anchor it to an adjustable slide. that way I wouldn't need a long heavy duty actuator and I could still get full travel by using it like an inchworm if I really needed more height than usual. If stock is 12", I'm sure that would serve my purposes.

Thanks for the info, I had heard about the surplus center but haven't looked there in quite a while.

Greg

[dahui]

Have you considered adding a gear motor to the existing screw? That's what I did and it work great. I got a brand new bodine gear motor off ebay for about 125 bucks, the rest is a bit of machining and switch wiring. I saw Boly's motorized column and that inspired me. He has some pics in his thread.

I also have some photos of my own version at: www.the-alchemist.com
Scroll down to "motorized mill column" on the menu at the left.

[sharpshooter90]

Grego,
If you go with the linear actuator, be sure it has the right amount of power. A lot of those on the surplus market were designed for satellite dishes. You need one designed for automatic gates.

[Grego]

Sharpshooter,

When looking at the longer actuators I was wondering how well they would hold up. I used to have a satellite dish with one on it and it didn't have to work very hard. I may just get a short one (also cheaper) and do the adjustable anchor trick. I can lock the head and relocate the anchor. I can probably live with 8" of adjustability or so, especially since the stock lift is about 12".


Dahui,

I dont' have the lead screw assembly, I would need to build the whole drive assembly. I'm kinda anxious to get machining on some projects and didn't want to add another to the list so this might save me some time.

Greg