Recommended Tools and Devices for Web Handlers

Note: TJWA Inc. does not represent or sell any of these products, unless noted. 

Diameter Measuring Tapes

Pi Tapes ™

Check roller diameter and diameter variations to 30 microns or 1 mil.

Pi Tapes are used to measure wear of rubber roller covers, diameter ratio of speed-ratio controlled rollers, and roller-to-roller parallelism as an alternative to a tramming stick.

The ‘easy to read’ product is highly recommend and worth the slightly higher price. 

Vimeo on using outside diameter tape (metric)

Vimeo on using outside diameter tape (American)

How to read a Pi Tape ™.

Precision Levels

Precision levels are required tool for aligning rollers and framework. Look for a level with several key features:

  • V-groove bottom for sitting squarely on cylinders.
  • Side level to indicate level is plumb atop roller.
  • Calibrated graduations to read in 0.5mm/m or 5 mils/ft

The most popular level in US is Starrett #98 Machinist Level, usually 12-inch length. They do make a more precise level, 199Z Master Precision Level.

A more compact alternative is the precision levels from EDA.

Tramming Stick

A tramming stick is a useful tool for checking roller-to-roller parallelism. Strangely not readily available from any supplier, most tramming sticks are custom-made. Also called a wiki-stick, named for its quickness, a tramming stick is comprised of:

  • An extending shaft (often a tripod leg)
  • A reference roller end, usually an angle iron modified to hold the tripod leg perpendicular to the reference roller
  • A dial indicator, measuring down to 25 micron increments over a 25mm range (or 1 mil over 1 inch)

The Nedo measuring stick is a compact and convenient tool similar to a tramming stick, measuring long lengths to small increments. One model measures down to 1 mm over a 0.5 to 2m range ( 40mil over a 20-80 inch range),

Durometer Rubber Hardness Tester

The Durometer is the international standard for the hardness measurement of rubber, plastic, and other non-metallic materials. Durometers are described in the American Society for Testing and Material specification ASTM D2240. The measurement is neither metric or American units, instead reads in units proportional to the penetration of a conic, spring-loaded probe where less penetration is considered ‘harder’ and scores a higher Shore value.

Shore A Durometer is used for most rubber covered rollers in web handling applications. Shore A Durometer measurements use a lower spring value and truncated cone probe. Typical Shore A values range from 20 (elastic band), 40 (pencil eraser), 70 (automobile tire),  to 90+ (shopping cart wheel).

Pusey and Jones Plastometer

The Pusey & Jones (P&J) hardness tester rates hardness based on the depth of indentation (in hundredths of a millimetre) of a 3.175 mm (0.1250 in.) diameter steel ball under a vertical force of 9.8 N (2.2 lbf). This value, read after 60 seconds of load, is opposite of Durometer with higher values indicating more indentation and softer rubber. A P&J of zero is the hardest rating, indicating zero indentation. P&J rating may be used to compare the indentation resistance of rubber and rubber-like materials, including paper rollers with a minimum thickness of 13 mm (0.5 in). P&J is based on ISO 7267 and ASTM D531-15.

Above, P&J Plastometer from 1915.

Handheld Force Gauge

A handheld force gauges are a tool any web handler should have. Forces are important in web processes (e.g., tension, nip forces), but many are not measured or directly controlled. A force gauge is vital to calibrate these mysteries. There are many levels of sophistication to force gauges, going from simple fish-weighing scales (see below), to mechanical push-pull gauges, to electronic load cells with digital output and recording. Look for a force gauge with a 25-50 kgf (50-100 lbs) range if you intend to use it by hand. Larger force gauges are useful for higher load measurement inline with a rope or cable (i.e., when not held by hand).