Demtech Pro-Wedge VM-20 Operator's Manual page 13

Rev. F, December 2020
Note: Pressure Adjustment for thin material and geotextiles:
These materials require less nip pressure. Too much pressure can cause
the material to perforate at the edge of the seam causing a "zipper" effect.
Make sure the heating wedge (#7, Figure 7.2) is in the disengaged position.
Turn the nip pressure adjustment hex nut (#11, F igure 7 . 2) clockwise while
looking down from above several turns, raising the nip arm up to give a fresh
starting point for this adjustment. (Loosen set screw(s) on hex nut first if present
to avoid damaging threads on eye bolts)
Place one end (one thickness) of your adjustment material between the nip rollers
and into the unit about 1" inch. Engage nip rollers by pushing down on the nip
lever until it has "clicked" into place and is held in position by the lock pin. At
this point the material should move around freely between the nip rollers.
Turn the hex nut (#11, Figure 7.2) counter clockwise until the nip rollers begin to
pinch down on the material and you cannot turn the nut by hand anymore.
This zeroes the adjustment.
Disengage nip rollers and turn the hex nut counter clockwise one full rotation.
Insert the adjustment material (the opposite end of the fold, two thicknesses)
between the nip rollers and engage nip rollers together until the lock pin clicks
into its detent as shown on the next page (Figure 3). Check pressure by attempting
to move the material side to side. If you are able to move the material or pull the
material straight out without the nip rollers turning, disengage the nip pressure
and turn adjustment nut (#11, Figure 7.2) counter clockwise ¼ turn at a time until
the desired pressure is reached. Remember to tighten the set screw(s) on the
adjustment nut after you have completed adjustment of the nip pressure to prevent
the pressure from backing off while welding.
Pro-Wedge VM-20 Operator's Manual Page 10