Re: Subassembly Kinematic mounting
- From: danek <danek@xxxxxxxxxxxx>
- Date: Thu, 21 Jun 2007 10:44:31 -0400
wadexkelman@xxxxxxxxxxx wrote:
On Jun 19, 1:56 pm, danek <d...@xxxxxxxxxxxx> wrote:Good to know. I had never heard of them myself. Thanks!Tom Hubin wrote:Hello,A simple machining procedure can be done to help this problem. Once you
I need to have a removable subassembly with good repeatability when
reinserted. Actual position is not an issue since optics are adjusted
with the subassembly in place.
I can use Thorlabs six piece set if necessary but I prefer something
that is more predictable.
Machining what I need is an option but I would prefer to work with
common breadboard with 1/4-20 holes on one inch centers.
So, I am looking for
1) magnets that screw into 1/4-20 holes,
2) ball-end screws that screw into 1/4-20 holes,
3) and mating slots or parallel rods that can be attached with 1/4-20
screws.
Second choice would be these same items but press fit or a different
thread.
Last choice is machining more and buying less. Not a happy choice for a
one-of-a-kind.
Tom Hubin
thu...@xxxxxxxxxxxxx
get everything fixed where you want it to go, drill through the mount
and into the breadboard in two places. Then you insert roll pins and
lift off the top part. You now have positioning pins to relocate the
mating piece in exactly the same spot. You must use two pins per piece
or the object can rotate around the pin.
P. Danek
Kinematic mounts are good, and magnets can provide a controlled amount
of force to keep things together (so you don't get variable
deflections with variable clamping forces), but if you need greater
rigidity along with the ability to take things apart, pins are very
good.
I wouldn't use roll pins, though. They scuff up the metal and
ultimately, when the holes enlarge, don't locate very well. Taper
pins are the way to go. They locate perfectly, are infinitely
removable, don't damage the parts, and have controlled shear strength
(since they are also used to limit torque in rotating shafts).
To install them, drill two straight holes through your adjoining
parts (of a diameter that is measured a tenth of an inch up from the
end of the taper pin reamer), then use a taper pin reamer to ream one
hole, insert the taper pin, then ream and pin the second hole. Pay
attention to the depth of the pin while you are reaming the holes.
Buy the kind of taper pin reamers that have a high helix reverse
spiral, and if the parts need to be kept clean (free of cutting fluid,
which is designed to adhere to surfaces and contaminate them), you can
use alcohol as a cutting fluid. It works well with aluminum and
evaporates afterwards.
If the holes are through holes, you can use simple taper pins.
(Stainless is best with aluminum.) If the holes are blind, you'll
have to use the threaded variety. McMaster-Carr has all of this
stuff.
Wade Kelman
P. Danek
.
- References:
- Subassembly Kinematic mounting
- From: Tom Hubin
- Re: Subassembly Kinematic mounting
- From: danek
- Re: Subassembly Kinematic mounting
- From: wadexkelman
- Subassembly Kinematic mounting
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