Hello, I am Jan Dolzer at Sutter Instrument.
This is a tutorial about three components that make up the Upper Pulley Assembly
on a Sutter horizontal puller: The Puller Bars, the Pull Cables and the Pulleys.
A defect in, or poor adjustment of each of these three components can cause inconsistency
and variability in your pull results. So Sutter Tech Support will point you to either this video,
or one of the three videos about the individual components.
This tutorial applies to the Sutter P-97, P-1000 or P-2000 Micropipette Pullers
as well as certain discontinued models.
Let's take a look at the Upper Pulley Assembly on this P-1000 Puller.
The three components that we will talk about today are the Puller Bars with their V-groove bearings,
The Pull Cables and the Pulleys.
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.
The pull cables are attached to the ends of the puller bars on each side.
They are routed around the upper pulleys and then over a pair of lower pulleys underneath the base plate
and on to the pull mechanism.
First let's make sure the pull cables are properly attached.
The end of each pull cable is terminated with a crimp-on swage.
The majority of the pull force is transmitted to the puller bar by the cable retaining screw.
Inspect the cable retaining screw and the swage on both sides.
Here is how it is supposed to look: The cable is firmly clamped, and the swage is parallel to the puller bar.
If there is a little gap between the swage and the hole in the puller bar, that is perfectly OK.
If the swage is at an angle, in contrast, the retaining screw is loose.
Once pull is applied to the cable, the swage rotates outward, and sideways force
is applied to the puller bar. Contact Sutter Tech Support if your puller looks like this.
Now let's take a look at the actual pull cable adjustment. Two aspects are important:
1. The pull cables must have a certain amount of play, and 2. The play must be the same on both sides.
To check for the correct play, unlock one of the puller bars from its spring stop
and move it to the center like this. Hold it at the finger bar with one hand
and tap the pull cable close to the rubber bumper. The cable should have about 2 mm of play.
In other words, you should be able to push the cable roughly until it sits on the bottom
of the cut-out in the bumper. Do not use too much force and make a kink in the cable!
Under no circumstances at all must the pull cables be under tension!
If you cannot pull the puller bars together until they sit against the hex screw in the
slotted hole: OUCH!! Call Sutter Tech Support immediately.
If the pull cable is tuned to C" (or any other note for that matter),
it is under tension - and it shall not be.
The second aspect to check is that the amount of play is the same on both sides.
Here are two techniques for this test: Pull the puller bars all the way together.
Now tap one puller bar against the hard stop and watch the lower portion of the pull cable
on THE OTHER side. You should see movement that corresponds to your tapping.
Reverse sides and repeat.
If you see the movement to about the same extent on both sides, you are good.
Another simple test is releasing each of the puller bars while holding the other one
at the hard stop. Both puller bars should drift outward by about the same distance.
If a pull cable is a little too tight or too loose, it can be adjusted to the correct tension
as described in the user manual. We strongly recommend, however, that you check back with
our Tech Support before digging into your tool kit.
Each Sutter horizontal puller has four pulleys. One on each end of the upper pulley assembly,
and two lower pulleys concealed underneath the heating element.
The pulleys on your instrument may either be silver, as seen on the P-1000 Puller here, or black.
The pulleys guide the pull cable and route it to the lower pulley assembly. Their smooth operation
is crucial for the uniform movement of the puller bars and reproducible pull results.
Over time, the small amount of lubricant that is contained in each pulley bearing will age
and may eventually freeze up the bearing. Debris particles from the air will team up
with the chemical aging of the lubricant to accelerate this process.
Sometimes a well-meaning human being who applied some inappropriate lubricant
to the bearings may have contributed, too.
To test the pulleys for proper operation, make sure the puller bars are clipped into
their spring stops. In this position, there is about a quarter inch of slack
between the pulley and the pull cable. Now spin the pulley like this.
If it spins for a full revolution or more, you are good.
On the filament pullers, drop the front panel and perform the same test with the lower pulleys.
If any of the pulleys on your instrument is sticky, that may account for inconsistent pull results.
On the P-2000 Laser Puller, it is not recommended to open the housing.
Please contact Sutter Tech Support if you have sticky pulleys or need help with the
lower pulleys on your P-2000 Puller.
Let me summarize what we learned today. Variability and inconsistency in your pull results
can be caused by defects or poor alignment of the puller bars, the pull cables or the pulleys.
This video teaches you how to determine whether each of these three components is in good shape.
The vertical alignment of the puller bars is critical for the proper operation and reproducibility of
your puller. Never attempt to adjust the play of the puller bars without consulting with Sutter Tech Support.
You want to clean the puller bars and the V-groove bearings every now and then proactively,
and if you observe variability, you definitely want to clean them.
The pull cables are designed to have some play, and the play must be equal on both sides.
The pulleys must spin freely. If any of them does not, your puller needs attention.
And last not least: Each of the moving components on your puller is designed to work without
regular lubrication. So lubing any of them is more likely to cause damage than to do any good.
Keep in mind that variability in the pull results can also be caused by inappropriate program parameters
or by issues with the heating element, i.e., the alignment of the laser or the heating filament.
Sutter Tech Support is there to work with you and determine the root cause of your particular issue.
Consider this video a diagnostic tool, but do not attempt any adjustments or repairs without
further guidance from us. We are happy to help, and we are there to help!
That's it for today. Check out our YouTube channel for the growing collection of Sutter tutorial videos.
To contact tech support, go to www.sutter.com
or give us a call at +1 415-883-0128.