Re: Backlash

Watch the video, I am only getting .0004" end play in the bearing. I
have spent $900 on bearings, each time I was told it has to be the
bearing. If the bearing was the problem, I would see most of the
backlash in the end play of the ballscrew shaft. On another mill I
have I measured .008" end play in the ballscrew shaft. I replace the
bearing and got it down to .0006".

Vince

>
> Vince,
>
> I've had good results with Hiwin screws. The only place I've ran

into backlash with them is in the endplate bearings. If its an asian
mill and has 6204 bearings in it they aren't double row angular
contact. The 3204 bearing is the double row bearing.

>
> Ron
>
>
>
>
>
> i
>
> Vince Endter <vince@...> wrote:
> I have been trying to chase down a backlash problem I

have with my

> Hiwin ballscrews for almost a year. I even sent the ballscrews back
> to Hiwin and they said there is no detectable backlash in them. I
> made a video of the test recommended by Hiwin. In the test I
> attached a ball bearing to the end of the ball screw shaft so I am
> not measuring any out of squareness in the end of the shaft. I am
> using a tenths reading (.0001") indicator on the end of the

ballscrew

> and a thousands reading (.001") on the table. I am measuring
> between .0003" and .0004" backlash in the end play of the radial
> contact bearing, and .004" on the ballscrew/table movement. The

gibs

> are adjusted to that if I push as hard as I can anywhere on the

table

> I can see only .0005" deflection. The mill was recently reground

and

> hand scraped by a professional machine tool rebuilder.
>
> There are only two places I can see the backlash coming from. One

is

> the yoke, which was supplied by Hiwin (very large cast iron, I

can't

> see that flexing), and the other is the ballnut/screw combination.
> The ballscrew has a single nut. Hiwin says they take care of back
> lash in one of two ways, either with a different pitch between the
> nut and screw, or by adjusting the ball size in the nut. They won't
> say which method is used in my installation.
>
> Here is the video of the test:
> http://www.flyingcritters.com/video/Backlash.wmv
>
> Any suggestion would be greatly appreciated.
>
> Vince
>
>
>
>
>
>
> [Non-text portions of this message have been removed]
>