Hello Stefan,
I use 2 screws.
As for the bearing size, If the bearings are too large for the size of the hexagon: -
the screws and ID will be too large for the hexagon bar carrier;
the bearings might interfere with each other and will not ride on the rail properly; and
will set the carrier and the rail too far apart.
If the bearings are too small there will be no clearance between the rail and the carrier.
HTH
Regards
John C
-----Original Message-----
From: Stefan Trethan [mailto:
stefan_trethan@...]
Sent: Sunday, 3 August 2003 8:42 PM
To:
homebrew_pcbs@yahoogroups.comSubject: Re: [Homebrew_PCBs] Re: re : sqare steel "pipes" as rails?
hi john
nice to see that, i already thought also of hexagonal stock
(one supplier in vienna has it on his items list)
maybe an option... we will see...
size of the bearings:
why is this critical?
i thought it doesn't change anything?
do you have the main axis driven by one or two threaded rods?
regards
stefan
On Sun, 3 Aug 2003 18:39:04 +1000, John Craddock
<
John.Craddock@...> wrote:
> Stefan,
> I used hexagon bar, like the bar used for making nuts and bolts, for the
> rails. I have uploaded a pdf into the files area under the folder JLC
> that shows a cross section of the setup. It uses roller-skate bearings
> and 3/4" or 19mm hexagon rail. The entire unit can be constructed using
> only a drill press. My table is 1 metre ∗ 600mm. It can be scaled up or
> down quite easily. the critical thing is the size of the bearings
> relative to the hexagon bar. I have used 12mm bar with 12mm bearings and
> 16mm bar with 17mm bearings also. The feed screws are 10mm ∗ 1.5mm pitch
> stainless threaded rod with bronze nuts that are split and cross screwed
> to take up the backlash. These screws turn in 10mmID ∗ 30mmOD deep groove
> bearings SKF number 6200VVCM. They cost AU$3.2 each; that is about 1.1EU.
> The roller-skate bearings were really inexpensive.
> Hope this gives you another idea.
> Regards
> John C
>
>
Be sure to visit the group home and check for new Bookmarks and files:
http://groups.yahoo.com/group/Homebrew_PCBsTo unsubscribe from this group, send an email to:
Homebrew_PCBs-unsubscribe@yahoogroups.com Your use of Yahoo! Groups is subject to
http://docs.yahoo.com/info/terms/