Re: [CAD_CAM_EDM_DRO] Which end to fix...

I don't see a major problem with having the far end fixed. Fixing the
end nearest the most heavily used end of the screw will give a very
slight improvement in accuracy but not enough to make a noticeable
difference. To be honest, I probably wouldn't even add a radial bearing
at the thrust end. Assuming everything lines up there should be no
radial load on the screw at that point. The radial bearings should be
able to handle any very small radial loads that do exist.

I am not sure why you would have 2 bearings at the other end. Surely all
you need is one to take the belt load.

Les


Henrik Olsson wrote:

> High guys,
>
>
>
> Got a manual machine converted to CNC by one of its former owners. It's not
> in operatable condition but I'm slowly getting there. My question is
> regarding the ballscrew supports.
>
>
>
> As it is now the X-axis screw is axially fixed at the NON driven side with
> two ordinary thrust ball bearings on opposite side of a shoulder in a block.
> The driven side is supposed to be floating axially and supported radially by
> a needle roller and either a standard deep groove ball bearing or a roller
> bearing to take the load from the belt tension - at least that is what I've
> been able to figure out so far.
>
>
>
> Qustions:
>
> 1) On just about every drawing I've ever seen of mounted ballscrews the
> driven side is fixed and the non driven side is floating (usually). So what
> are the drawbacks of having the non driven side fixed as they've done on
> this machine? Can I leave it as it is or should I rebuild it so that the
> driven side is fixed (if possible)?
>
>
>
> 2) What about the thrust bearings? I'll probably add a deep groove ball
> bearing to the fixed side to gain radial support since the thrust bearings
> are meant for that but except of that, can I keep it like it is or should I
> go for angular contact or tapered roller bearings as "it's supposed to be"
> (means I have to fabricate new bearing blocks)? Buying special ballscrew
> support bearings is not an option at the moment so if I'm changing it'll
> have to do with standard 72xx series A/C's or tapered roller bearings.
>
>
>
> Looking forward to your advice!
>
>
>
> Regards
>
>
>
> /Henrik Olsson.
>
>
>
>
>
> [Non-text portions of this message have been removed]
>
>
>
> Addresses:
> FAQ: http://www.ktmarketing.com/faq.html
> FILES: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/
> Post Messages: CAD_CAM_EDM_DRO@yahoogroups.com
>
> Subscribe: CAD_CAM_EDM_DRO-subscribe@yahoogroups.com
> Unsubscribe: CAD_CAM_EDM_DRO-unsubscribe@yahoogroups.com
> List owner: CAD_CAM_EDM_DRO-owner@yahoogroups.com, wanliker@..., timg@...
> Moderator: pentam@... indigo_red@... davemucha@... [Moderators]
> URL to this group: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO
>
> OFF Topic POSTS: General Machining
> If you wish to post on unlimited OT subjects goto: aol://5863:126/rec.crafts.metalworking or go thru Google.com to reach it if you have trouble.
> http://www.metalworking.com/news_servers.html
>
> http://groups.yahoo.com/group/jobshophomeshop I consider this to be a sister site to the CCED group, as many of the same members are there, for OT subjects, that are not allowed on the CCED list.
>
> NOTICE: ALL POSTINGS TO THIS GROUP BECOME PUBLIC DOMAIN BY POSTING THEM. DON'T POST IF YOU CAN NOT ACCEPT THIS.....NO EXCEPTIONS........
> bill
> List Mom
> List Owner
>
>
> Yahoo! Groups Links
>
>
>
>