RE: [CAD_CAM_EDM_DRO] Re: Which controller card for EMC? Ballscrew Class ?

BTW Jim,

EMC DOES have error mapping of the ballscrew.
I measure the accuracy with long gage blocks derived
from micrometer standard test bars. I use a mechanical
cam arrangement to match the tandem x axis screws.

Hiwin precision rolled screws are of 4 point contact gothic arch
type...with oversized balls. Combined with mapping I get
about +/-0.0005" within the work envelope at 25c. They grow quickly
as they get warm. I think emc has temperature growth compensation,
but I currently don't use it.

Only disadvantage is 4 point contact screws have a lot more ball
skidding and therefore might not last as long.

Accuracy class definition is dependent on the manufacturer.
A more standard measure is E300...position error due to pitch
deviation in 300 mm or about a foot.

Les

Leslie M.Watts
L M Watts Furniture
Tiger Georgia
(706) 212-0242

Main page:
http://www.lmwatts.com
Engineering:
http://www.lmwatts.com/shop.html
Cnc surplus for sale:
http://www.lmwatts.com/forsale.html
Carved signs:
http://www.lmwatts.com/signwp.html


-----Original Message-----
From: CAD_CAM_EDM_DRO@yahoogroups.com
[mailto:CAD_CAM_EDM_DRO@yahoogroups.com]On Behalf Of Jim Colley
Sent: Wednesday, September 28, 2005 1:16 PM
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: [CAD_CAM_EDM_DRO] Re: Which controller card for EMC? Ballscrew
Class ?


--- In CAD_CAM_EDM_DRO@yahoogroups.com, "turbulatordude"
<dave_mucha@y...> wrote:

>
> Class 3 ballscrews ? didn't we just have a discussion about ball
> screws ? I don't remember anyone bringing in something like
> industrial gradeing systems or classes, but more on rolled vs.

ground.

>
> I think further reading is in order.
>
> Dave

I have done a lot of looking around and for what I can find
appropriate size and lead rolled ballscrews for, I can very patiently
await a rare find for some good precision ground ballscrews. I have
one Class 1 Kuroda ballscrew from eBay that I snapped up for about
$225 for a 14in travel, .200 lead, dual nut screw with end blocks and
bearings. If anyone knows where to find more accurate rolled screws,
I'm all ears. It's all about accuracy and price. I'm so far from
actually building at this point and working primarily on the layout
of stuff I already have, that I can be patient about the ballscrews.
Using Pro/E for a top down design, changing a spec or two here and
there really doesn't pose much of an issue if I have to gain or lose
an inch or two of travel here and there.