precision linear positioning with a ball detent
precision linear positioning with a ball detent
(OP)
Hi!
I am looking at feasibility and execution of using a ball detent for precision manual linear positioning in a small, lightweight handheld consumer product.
Will need .001" (or better) accuracy over a range of ~1" travel, with about 30 individual steps. likely using ultem for the main body of the system.
I do not think of a ball detent as a precision system, but in theory, I can not see why not. please discuss, and ask questions as necessary!
thanks
I am looking at feasibility and execution of using a ball detent for precision manual linear positioning in a small, lightweight handheld consumer product.
Will need .001" (or better) accuracy over a range of ~1" travel, with about 30 individual steps. likely using ultem for the main body of the system.
I do not think of a ball detent as a precision system, but in theory, I can not see why not. please discuss, and ask questions as necessary!
thanks





RE: precision linear positioning with a ball detent
RE: precision linear positioning with a ball detent
One fixed and one that can be lifted to allow them to disengage and allow movement.
RE: precision linear positioning with a ball detent
RE: precision linear positioning with a ball detent
The clearance left-right is going to need "some" clearance anyway, so that requires the hole be slightly oversize anyway. Then, even if the left-right accuracy is 100.0000%, the x-x linear position is going to also be variable by the same hole size. If you don't use a full-depth hole, then the whole assembly could move both left-right (y) and linearly (x-x) sicne only a part of the ball detent would go up into the partial-depth hole.
RE: precision linear positioning with a ball detent
The cone shape should deal well with wear as long as the mated distance between the two parts is not important. What I mean by that is the parts are constrained in the x-y plane by the cup and cone and have allowable slop in the z direction to allow for changes in mated height due to wear.
Still, 0.001" repeatable accuracy could be very difficult with the small features that would be necessary for 1/30" steps. Could you share more about you application and why you need the high degree of accuracy?
RE: precision linear positioning with a ball detent
RE: precision linear positioning with a ball detent
The first stage has course pitch to get you in the neighborhood quickly, then the second stage had finer pitch for accurate positioning.
RE: precision linear positioning with a ball detent
Mike Halloran
Pembroke Pines, FL, USA
RE: precision linear positioning with a ball detent
his leaves the ball with point loadingThis suggests using an undulating semi-circular shape on the teeth as it ratchets, so the plastic and the preload need to be low enough to withstand it. If possible, a pre-load relief for when the user is positioning the item.Are you trying to measure a distance or save a distance? If it is measuring, I'd look at using a moire pattern; basically an optical vernier.
RE: precision linear positioning with a ball detent
RE: precision linear positioning with a ball detent