Frequently Asked Questions

A strong customer service orientation together with technical expertise and reliability has led to the development of a very loyal and always increasing customer base. Luigs & Neumann’s quality product support is the best way to keep this good relationship and will help find solutions to any questions and technical problems relating to operation, specifications and applications that might occur.

Manually/Motorized Operated Manipulators

Question/Problem:

• Moving a manipulator is accompanied by a strange noise (grumbling or scraping).
• A manipulator moves too easily, making it difficult to set it to a desired position or causing it to go out of position.
• A manipulator descends by itself out of a set position in any of the axes (possibly the z-axis).
• A manipulator descends by itself due to loose tension.

Probable cause/Description/Answers:

The principal cause of a manipulator’s failure to move smoothly after long use is the wear and tear of diverse components (bearings, screws, nut threads etc.). This primarily can lead to tension or loosening of certain mechanisms.

Tension adjustments can be made when the manipulators get to stiff or to loose. It is best to send in the device to the Luigs & Neumann workshop. The engineers will exchange any parts that are worn-out, readjust all settings and run new tests to ensure optimal use.

Problems of drift

Mechanical or position drift

Question/Problem:

• Mechanical or position drift is causing problems.
• Manipulators and cables are causing drifting problems.

Probable cause/Description/Answers:

Position drift is described as the relative movement of the pipette tip in respect to the cell or other feature on the slide and can come from numerous sources. Various aspects can influence the precision and lead to drifting problems.

Mechanical or position drift can be caused by any of the mechanical components listed below:

Mechanical or position drift can be reduced or prevented when regarding the following aspects:

• Make sure that the mounting system is stiff and stable.
• Do not clamp the head-stage too tightly.
• Make sure that all clamp adapters are fixed correctly (loose or unstable connections can produce drift).
• Check the correct position of all fixed and adjustable parts.
• Whenever it is necessary to exchange a screw on the mechanical stages and clamps, always check the length and make sure that it is not too long and does not scrape the bottom of its hole.
• Make sure that none of the locking mechanisms are sticking.
• All manipulator movements are to be smooth, free of friction and working properly when activated.
• Secure all cables with enough slack, see that they are sufficiently tied and do not apply any tension on the manipulators or they can interfere with the work.
• Always adjust the pipette in consideration to the working distance.
• Avoid any contact between pipette and bath chamber or objective.
• Handle the manipulator with care (never touch it roughly).

When using rotary or folding manipulator clamps, the wires on the manipulator and headstage might be bent and twisted.

• Use large service loops and cable support elements.
• The cables are very flexible when given a few centimetres of free length. Make sure that all the cables are loose throughout the range of motion and stages.
• Ensure that no cables are pinched, compressed or stretched.
• Do not let any cables interfere with any procedures.

Thermal drift

Question/Problem:

• Drift due to thermal expansion or temperature variations.

Probable cause/Description/Answers:

Reasons for drift caused by thermal expansion or temperature variations can be:

Each time a manipulator is exchanged, the cables are flexed and the insulation produces residual stresses. As these residual stresses are relieved over time the forces on the manipulator change and can cause apparent drift. Cables might be pinched, compressed or stretched.

In order to avoid drift, please consider the following guidelines:

Minimize temperature gradients and prevent temperature variations by making sure:

• that there is no draught (keep doors and windows closed),
• that the air conditioning is switched off (the air conditioning causes peristaltic vibration and temperature drift) and
• that the sun does not shine directly onto the set-up.
• And please also allow a certain warming-up time after switching on the power of the set-up (most technical components need a warming-up time of approx. one hour to ensure optimal use).

In general, isolate the microscope away from air conditionings, sunlight or any other sources of heating or cooling. In the most sensitive cases, isolate your body heat from the workstation. If your equipment is exposed to temperature changes due to installation, handling or environmental changes, let it stabilize for up to one hour.

An often neglected aspect is the thermal expansion of selected material:

• Avoid temperature-sensitive materials such as polymers (composed of one or more large molecules that are formed from repeated units of smaller molecules).
• Aluminium for example has a high thermal conductivity and quickly reduces thermal transition and is therefore ideal to use in a structure. In general, when using the same material, the structure is insensitive to the slow changes in temperature that typically occur in a laboratory.

Checklist for problems with manipulators or drift

The following checklist is of help to locate the exact problem for when a manipulator drifts, springs or vibrates when using the handwheels or when operating the step motors.
A further problem could be that the manipulator might jump when cutting of the power supply.

1. Remove the headstage and the headstage holder from the guide rail.
2. Stick the electrode directly on to the guide rail using sticky tape.
3. Bring the electrode into focus
4. Check again for any apparent drift Yes / No