RE: [CAD_CAM_EDM_DRO] Re: Need ballscrew support Bearings.

Hoffman bearings in Chelmsford used to be a regularly shipment of bearings
AND ball screws to the UK Bridgeport Builders, as well as Colchester,
Harison and all the other CNC machine makers back in the 80's, I worked just
down the road from them, used to smuggle my car into their carpark.

I don't know whether Hoffman made the screws, or bought them in, possibly
the cheap Jap screws were the cause of their demise.

It wasn't long into the 80's before they went bust.



I think most these manufacturers will have not stuck to one screw
manufacturer but played prices off between them every few years.



Dr. Mark Vaughan Ph'D. B.Eng. M0VAU

Managing Director

Vaughan Industries Ltd, reg in UK no 2561068

Water Care Technology Ltd, reg in UK no 4129351

Addr Unit3, Sydney House, Blackwater, Truro, Cornwall, TR4 8HH, UK.
Phone/Fax 44 1872 561288

RSGB DRM111(Cornwall)

_____

From: CAD_CAM_EDM_DRO@yahoogroups.com
[mailto:CAD_CAM_EDM_DRO@yahoogroups.com] On Behalf Of Jon Elson
Sent: 19 April 2007 03:24
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: Re: [CAD_CAM_EDM_DRO] Re: Need ballscrew support Bearings.



Polaraligned wrote:

>>I got just the bare ballscrew/nut in original factory package on
>>eBay last year for under $60. Made in China for Bridgeport. It
>>was definitely NOS, over 20 years old, but still in great shape.
>>Now, I just need to find an X screw like that!
>
>
> The BOSS machines used high precision ballscrews made in
> Japan by NSK.
> This was confirmed by my conversation with a gentleman at
> Hardinge who is the BP parts expert and worked for BP for 30
> years before they closed.
>
>

No telling why Bridgeport bought this ballscrew. Possibly to
evaluate the manufacturer, or for a special project, or
overhaul of an old machine. It appears that it is made to
fit a Bridgeport mill, not just something Bridgeport ordered
for their shop. I suppose it also could be specsmanship, and
Bridgeport actually never touched the part.

>
>
> Well Jon, I am not looking to make any alterations to the setup
> to get a preload. I was thinking about just using regular
> angular contact bearings and using a surface grinder to grind
> a little off of the inner race to get my preload. I am not sure
> how much I need. The Fafnir original replacement bearings are
> available in light, medium and heavy preloads.
>
>

I would rather make some rings to set the preload. If you press
the races together and the inner rings are not touching, then
you could put shims between the inner or outer races, depending
on the setup, to apply the preload. The rings/shims would be
a lot easier to manipulate than grinding on bearing races
directly. Not only do you have to worry about grit getting in
the bearings, but that is a pretty irreversible process. If you
muck up the spacers, you can do them over again.

Jon





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