Re: [CAD_CAM_EDM_DRO] Re: no thrust bearing

On Sat, 19 Apr 2003 05:32:41 -0000, you wrote:

>>How does one attach a leadscrew/threaded rod to a thrust bearing?
>>Does one just make sure that the diameters are a tight fit, or are
>>there screws to tighten or something?
>
>"Probably not screws, but you might use a collar, which then forms
>the surface pushing against the thrust bearing."
>
>Ahh! How about this simple method. I get a threaded rod ====== ,
>screw in a bolt () at one end, insert the screw into a (any) bearing
>% sitting in machine housing, screw in another bolt (), with some
>screw thread left over for the coupling to the shaft. Then the 2
>bolts will hold the bearing firmly in between them.

Works if the inner race of the bearing is bigger than the outer, or
that there's no drag.

>
>========()%()===
>
>How does that sound for a quickie no fuss solution for a beginning?
>
>"Many people use a flexible coupling of some sort, since it makes the
>stepper alignment a little less critical."
>
>Flexible coupling like the tubing for domestic cooking gas?

No. Flexible couplings can look mechanically like the universal joint
in a socket wrench set. You can have two interlocking pieces that are
coupled by a rubber spider. The spider flexes, and allows the shafts
to be misaligned a bit.

>"I'm not sure of the real question."
>"drill rod is a good quality steel, not particularaly straight ....."
>
>I sort of guess that drill rod is toolsteel for making drill bits?
>But what I was getting at is I think drill rod is American Lingo.

Right, it's a variety of steel that's easy to temper. It can be air,
oil, or water hardened. You heat it up red hot, then dunk it in
whatever medium it's made for. Then you heat it again to temper it,
but only to about 400 degrees...

Some of it is ground, or precision ground. Generally a better grade
of steel, and since it is not cold rolled, has less internal stresses.

>Don't know what they call it here, and don't think they have it
>anyway because most people don't know what a drill rod is.
>

Silver steel.

>"Regarding thrust bearings, you can make a block with a bearing for
>the axial load, and attach plates then add thrust bearings. Thrust
>bearings are often very very inexpensive so if you have the ability
>to use them, do so."
>
>How about the scheme I described above as a subsitute. Haven't used
>thrust bearing before.

If there's a sufficient load on the bearing, through the bearing, you
can push the bearing assembly apart. Thrust bearings are made to take
a push towards them, so they won't pop the bearings out.

Look at a bearing like a wimpy's sandwich... two washers are the buns,
and the inner meat patty is a ring of captive ball bearings. thrust
tries to squish the bearings into the thrust washer, not push them
out.

that kind of bearing has poor resistance to play along the radius of
the rod... You can combine it with both kinds of ball bearing, or you
can get a conical bearing (they use them for car axles....) that have
cone shaped races, and rollers for the bearings...

It will take thrust in one direction axially, and all directions
radially.

>
>"mcmaster-carr can be very helpful here and still be done cheap...I
>just added new trust washers to my Y and they cost 5 bucks for the
>12mm size...two needed"
>
>When will McMaster-Carr go international - like Farnell or something?
>Hopefully before I retire as as cadcamoholic.

Since I'm on the other side of the pond, I can't say what's available.
Sorry that I can't help more.

Harvey

>
>Andrew
>