SoliForum - 3D Printing Community — Replacing z axis leadscrew idea

Re: Replacing z axis leadscrew idea

2013-07-27T00:01:53Z

that is indeed interesting!

Re: Replacing z axis leadscrew idea

2013-07-26T22:24:53Z

cmetzel wrote:

http://www.thingiverse.com/thing:112718

And you beat me to it here too.

Re: Replacing z axis leadscrew idea

2013-07-26T19:37:57Z

http://www.thingiverse.com/thing:112718

Re: Replacing z axis leadscrew idea

2013-03-22T19:38:33Z

Who among the worst of the z banding people wouldn't pay $100 to have zero banding forever? I don't have the time to try something like this and I can't afford the downtime right now due to a couple projects I'm printing. But I'd be very interested in the outcome for a future upgrade.

I'm not sure why an encoder would be necessary, you would still home with the limit switch, switch to incremental movements and go from there. You'd have to modify some lines in the firmware to match the "pitch" or they call it lead I beleive of this actuator, but you could need one if they say you lose .002" accuracy per revolution. Like I said that may be the deal breaker on it.

Re: Replacing z axis leadscrew idea

2013-03-22T19:28:32Z

I'm looking at some actuators for a project I am working on and they all seem pretty pricey. I think that you will need to add a rotary/optical encoder on this in order to provide positioning information as well.

Replacing z axis leadscrew idea

2013-03-22T19:19:30Z

I had another idea about replacing the lead screw altogether with what's called a Roh'lix linear actuator.

http://www.zero-max.com/linear-motion-c … -l-en.html

Roh'lix website wrote:

Roh’lix Actuators have six precision ball bearings, three at each end of a two-piece aluminum block.
Mounted at an angle relative to the drive shaft axis, the bearings convert drive shaft rotation into proportional linear travel. This is called lead. The linear thrust capability of the Roh’lix is determined by the friction between the smooth surfaces of the angled bearings and the drive shaft.
Thrust capability is varied by adjusting the cap screws located on the top of the load block. Loads exceeding the thrust setting cause the Roh’lix to stop while the bearings rotate in place as long as the drive shaft is turning.

1/2 dia shaft can handle up to 60lbs thrust. This would eliminate wobble completely, but there are 2 items that scare me a little.

roh'lix wrote:

Backlash
Roh’lix bearings are preloaded by the coil springs to reduce backlash to less than 0.001 inch, which help maintain consistency throughout the life of the bearings.

This is much better than the lead screw we're using now so I think .001 is acceptable, especially since we're travelling at such slow speeds in Z

roh'lix wrote:

Positioning Accuracy
The Roh’lix is a friction drive device and as a result, will show an accumulated error that is, in general, up to 0.002 inches per shaft revolution. Where greater accuracy is required, linear encoders can be used to indicate position.

Might be the deal breaker unless you encorporate a stepper with built in encoder, but they get pretty expensive.

According to the PDF they are designed for axial loading, not for side loading like they'd be used in our application, but I'm wondering if you spec out 60lbs thrust and you only need a small portion of that could you overcome that limitation?

Just contributing to the conversation, might be a good one to sick Kendall on since it seems like he's got some parallel research going on.