Re: Linear bearing types?

Hi Don,

I don't have a lot of experience with lead bearings except the one in my
fly-press but I have seen them used a number of times. I agree that, as
with all techniques, this one has its own place and I suppose there
would be design considerations which may preclude its use in certain
situations. Presumably, the screw working with such a bearing would need
to be at a coarser pitch than for say a bronze bearing and the nut may
need to be several times as long to get enough load spreading. I
certainly won't be using this type of feed nut in the miller I'm making
now, it will have a split nut - either split on the diameter with a
pinch screw if I decide to use a 'V' thread or split t'other way with
pinch screws to draw the two parts together if I go with a square or
acme thread. This way both the shake and friction can be adjusted
whenever necessary.

Ian

Don Hughes wrote:

>
> From: Don Hughes <pencad@...>
>
> Ian:
>
> In response to your post here about babbit bearings, I have worked in
> the past most extensively with babbit.
> My comment is this. Having worked so much myself with babbit, you must
> have the lead at the right temp. to pour and make a "good" bearing. I
> believe we used to pour at around 350deg C to ensure a solid pour for
> the bearing and the consistency. The machines that we had the babbit
> bearings on were larger engine lathes, swinging approx. 60+ inches and
> located in the headstock where we weren't turning the spindle all that
> fast. Truthfully, after seeing the amount of rigidity that is required
> for CNC applications in the rigorous movement of the axis' at the given
> feed rates, I don't feel babbit is the best way to go.

Best wishes

Ian

--

Ian W. Wright LBHI
Sheffield Branch Chairman of the British Horological Institute.
Bandmaster and Euphonium player of the Hathersage Brass Band. UK.
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