Re: Linear rail & ball screw size suggestions

Hi Mike,

I think I speak for us all when I ask you to post a link.

Nothing wrong with good quality at fair prices.

And for what I have read, there are those of us who will spend 10
hours to save $10.00. I know I have done that. sometimes by design,
others by lack of it.

Dave

--- In CAD_CAM_EDM_DRO@y..., "dumbdrive" <mclem@b...> wrote:
> --- In CAD_CAM_EDM_DRO@y..., JanRwl@A... wrote:
> > In a message dated 09-Apr-02 20:42:31 Central Daylight Time,
> js3mc@a...
> > writes:
> > There are "non-round" ways to do this, too, such as the fine
stuff
> > made by HIWIN, THK,
> > etc., but I think you are talking serious $change, there.
>
> I normally only lurk here but I feel I need to say something about
> linear bearings... I've just noticed over the past several months
> that there has been some discussion about linear bearings... some
> trying to build their own, others using skate wheels, etc...
>
> The square rail linear bearing market has become very competitive
> here lately... For example I sell Hiwin... If you wanted a size 20,
> (comparable to the THK SR20) the blocks (recirculating units) are
> $34.50 each... and the rail is $2.24 per inch... For example an 18"
> rail is $40 and a 24" rail is $54... and you can get ANY length you
> want up to around 6 feet, before you have to join two rails
> together... They are cut to length in Chicage at the Hiwin
warehouse
> and shipped directly to you, it takes about 1 week.
>
> These prices are drastically different from several years ago when
a
> similar rail was $4/inch and bearing blocks were $80+...
> I believe that these prices have made the supported Thomson
shafting
> and blocks look expensive for what you get... the size 20 has a
load
> capacity of 1400 lbs... you would need a 1.5" diameter Thomson
shaft
> to get the same capacity.
>
> Hiwin ball screws are also dropping in cost... a 1" diam ballscrew
> with .200 lead, preloaded flanged ballnut, 49" OAL, (need the ends
to
> be machined) is $185... this is a nice screw!
>
> If I was building a machine, I would want it stiff, I wouldn't want
> the tool moving around on me... the bearings and the screw are the
> heart of stiffness. I know, I know... it's only a light load, and
> little forces... but someday you are going to put a 3.5 hp router
> head, and up the speeds, it's only natural, as Tim Allen says "more
> power". You're going to need a system that can handle it, or
you're
> going to rebuild the present system... what's that saying
about "not
> enough money to build it right but always enough to rebuid it"?
>
> Enough said... back to lurking...
>
> ps... if you are interested in getting some rails and/or screws
> contact me OFF the list.
>
> Mike