Puller Bars and V-groove Bearings
Puller Bars and V-groove Bearings


Hello, I am Jan Dolzer at Sutter Instrument.
Today we will show you a short tutorial about the puller bars and the V-groove bearings
that position and guide them. A puller bar that has too little vertical play
or is even dented is one of the possible root causes for variability in your pull results.
So our Tech Support will ask you to check your puller bars and a few other components.
This tutorial applies to the Sutter P-97, P-1000 and P-2000 Pullers as well as
certain discontinued models. The puller bars hold and position the glass
capillary before the pull. More importantly, they control the movement of
the capillary while the pull is executed. So it is crucial for appropriately shaped and
reproducible pipettes that the puller bars are completely straight, parallel and in a
well-defined position. To achieve this, each puller bar is carried
by three V-groove bearings. The puller bars must have some vertical play
in the V-groove bearings. To test this, unlock the left and right
puller bars from their spring stops. Now grab one of them at the narrow section
and move it up rapidly up and down. You should hear a clicking sound and
clearly feel some play in the bearings. Since each puller bar is supported in the
V-grooves of the bearings, its position is defined by the location of the two lower bearings
and the amount of play in the upper bearing. This was adjusted in the factory and will not normally
need any readjustment for the life of the instrument. If a puller bar has no play at all,
it will not move smoothly, and there is a high probability that it is dented by being pressed
against the upper V-groove bearing. The puller bars are made of high-quality tool steel,
and we put a lot of effort into making sure they are perfectly straight. And because of this,
the steel that the puller bars are made of cannot be hardened.
So the bars are softer than they look. That means, on the other hand, that when trying
to eliminate the vertical play, it takes only very little overshooting to put a dent in
the puller bar. And while that dent may not look like much more than a shiny spot,
it does not allow the puller bar to run perfectly straight anymore and may
completely ruin your pull results. Therefore: Do not try to adjust
the vertical play of the puller bar, unless instructed by Sutter Tech Support. In addition, do not apply a lot of horizontal
force to the puller bars to avoid bending them. It pays off to clean your puller bars and
V-groove bearings from time to time. Use a cotton swab wetted with ethanol or
isopropanol to remove dirt build-up from the V-grooves and their mating surfaces
on the puller bars. Do not apply any lubricant to these surfaces,
or to any of the bearings on your puller. This video is meant as a diagnostic tool.
Please contact Sutter Tech Support for further guidance before making any adjustments
or attempting repairs. Visit our web site or our YouTube channel to watch
the growing collection of Sutter tutorial videos.

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