Unfortunately I don't have a force-gauge to hand but, indeed, using the calculator with a 0.1 coefficient of friction was expecting circa 20Ncm-1 torque to raise and in reality it "felt" like quite a bit more when turning by hand. My NEMA 17 stepper was unable to cope.
However it did all work...
I've a short bar of teflon and made a 15mm wide lead nut for a M12 steel rod (standard thread) to build a silent linear actuator mechanism.
The nut raises a platform with a load of up to 250N.
Have limited material to experiment, so don't want to proceed entirely by trial and error.
Can...
This sounds right. Thanks guys.
I need to find a lower precision / robust OTS solution.
My suppliers have more precision type CNC linear guides which are overkill.
Will now start looking further afield. Trying to find the right search terms so that don't end up wading through lots of higher...
I'm satisfied with the precision of the above arrangement but it was just a naive assumption that it would become a cost effective approach.
Items like Hiwin HG guides have a lot of extra precision that didn't seem warranted here (purpose is to lift a container of food up and down) and so the...
I've been happily working on a platform design as above (500mm long, 350mm wide, vertical angle-irons 450mm long; cylinder represents linear actuator). The purpose is to provide 300mm of vertical motion and carry a load up to 20kg (that could even be placed at the far end).
The rollers are...
@MikeHalloran those are just CAD models with "bonded" defined in software.
In "reality" the rod will reach downwards further and above will be flush with the top of the horizontal bar.
I did have a prototype quite similar and surprisingly the bar didn't seem to work upwards under load, though...
GregLockock, @BrianPetersen Sound real world suggestions. Love the idea of a taper. Trying to figure out how to model that with pre-tension.
@Buggar: sensible as ever this remark. Need something smaller, however, and to find room for encoder and slipring (not mentioned here).
@Tmoose Stress...
A 20mm steel rod is held vertically by a dry plastic cylindrical bearing such that it can rotate freely in the horizontal plane.
An aluminium bar with a 20mm hole in it is slipped onto the rod and, supported by the bearing below, can rotate freely in the horizontal plane.
The bar must support...
@Tmoose that is great info.
This forum is excellent!
So 4 bolts facilitates adjustment....
Am I right in thinking that a bolt/shim arrangement is likely to be stronger than a levelling screw with ball joint arrangement of the same bolt size? Because whereas each levelling screw is like a...
Excellent. Thanks!
In order to allow for a certain angle of tilt adjustment:
a) would 3 bolts in the flange be the optimal number (since that defines a plane, as with the theodolite with its levelling screw system)?
b) presumably the holes must be drilled loose to allow for the bolts to sit...
@GregLockock The base is 1m wide and 0.6m deep. The structure 0.9 high.
How would you use shims to adjust? The issue would be attaching the part/adjusting such that the arm is horizontal in all directions.
@3DDAVE here's a sketch. The system supporting the arm should be as slim as possible (circa 50mm) in the horizontal plane, though it can be quite tall. It's mounted on a vertical bar that's presently 20mm wide and 40mm deep (some flexibility there). http://i.imgur.com/bO9X5Sq.jpg
@BUGGAR axle...
Excellent @BUGGAR
That's two good suggestions.
- Seems that automotive-hub-bearings handle an impressive range of loads. Great one stop solution. On the downside they are quite chunky (outer diameter 13cm upwards?). (By contrast could choose a 20mm rod and find bearings with an OD not much...
