Finely Setting The Correct Saw Tensioning (Fig. 6); Working With The Saw; General Information For Working With Mechanical Fret Saw; Selecting The Saw Blade - Proxxon DSH Mode D'emploi

5.7.2

Finely setting the correct saw tensioning (fig. 6)

Correct saw tensioning is an essential factor for a clean work result.
This must, therefore, be carefully set. If over or undertensioned, the saw
blade can lightly crack. Turn knurled button 1 to set the tensioning. If the
button is moved to the right (clockwise), the saw blade is more tightly
tensioned. If it is turned to the left (anticlockwise) the blade is loosened.
A correctly tensioned blade sounds a slight tone if "plucked" like a string.
6

Working with the saw

6.1

General information for working with mechanical fret saw

The mechanical fret saw is predominantly a machine for sawing curves
and precise sections. A typical application is shown in fig. 7. The work
piece must be carefully guided by the operator. Note: Mechanical fret
saws are normally operated without length stop, as the saw blade loses
its line íf forced in, particularly in the grain of wood.
Please note that the saw blade only saws in reverse motion in the direc-
tion in which the teeth point.
For good results, please note the following points:
– When sawing, press the work piece onto the work plate (fig. 7), guide
by feeling and with little power; more pressure on the work plate, less
pressure against the saw blade.
– Make sure that the work piece is lying properly on the saw table (nor
burrs or sawdust)
– Adapt the feed to the requirements by saw blade, speed and work
piece material.
– Hard materials, fine saw blades and thicker work pieces do not "tol-
erate" as much feed as soft materials, rough saw blades and thin
work pieces. You can also experiment with various speeds.
– Guide the work piece slowly into the saw blade, particularly if the
blade is very thin and the teeth very fine or if the work piece is very
thick.
– Only use perfect saw blades.
– Do not let the device operate unsupervised.
– Carefully mark out/block the check line.
– Make sure there is good lighting.
– Always work with connected vacuum cleaner and carefully set the air
nozzle (8, fig. 1).
– You will achieve the best results if the wood thickness is under
25 mm.
– With wood thicknesses of greater than 25 mm, the work piece must
be very carefully guided to stop the saw blade from jamming, bending,
twisting or breaking.
– For precise cutting, note that the saw blade will always try to follow
the direction of the fibre (applies particularly to thin saw blades).
6.1.1

Selecting the saw blade

As already mentioned, the correct selection of material has a very great
influence on the quality of the result. The table below should serve as a
small guide. Extensive experience with many materials and types of
saw blade is, of course, always helpful with selection. You can experi-
ment here.
Tip: The saw blades are mostly only particularly worn at places where
the teeth are particularly highly utilised when sawing and, therefore,
become blunt very quickly. To "use up" the non-worn teeth and thus
increase the edge life of the sawing blades, you can artificially "raise"
the bearing surface for the work piece somewhat.
To do this, simply secure a smooth, table-sized underlay with the required
thickness to the saw table, using, for example, double-sided sticky tape.
The non-worn parts of the saw blade are now sawing the work piece.
This is particularly sensible if you often saw very hard and wear-intensive
materials with thin blades.
The numerical data for characterising the "fineness" of the toothing is
related to the number of teeth per inch of saw blade length:
Teeth/inches Material
approx. 10-14 Soft and hard wood (from approx. 6-50 mm),
plastics, soft materials, thicker work pieces
approx. 17-18 Fine sawing work, wood (up to 6 mm), plastics,
soft materials, thinner work pieces
approx. 25-28 Plastic, GRP, non-ferrous metal, Plexiglas, iron
with restriction Pertinax
approx. 41 Iron, Pertinax
Round sawing blades (with flat ends) can ideally be used for plastic,
hard and soft wood. They cut on all sides, so it is not necessary to turn
the work piece when sawing.
Please note in general:
PROXXON bits and cutters have been designed to work with our ma-
chines, which makes them optimal for their use.
We will not assume any liability whatsoever for the safe and proper
function of our devices when using third-party bits and cutters!
6.1.2

Selecting the speed

This representation can, of course, only give instructions on the general
direction to take. As in the previous section, you have to "experiment" a
little to find the optimal result. The appropriate speed also, of course,
depends on the blade used, the material of the work piece, the feed etc.
Level Material
900 strokes/min Steel, brass, non-ferrous metals, GRP, plastics
1400 strokes/min Aluminium, wood, polystyrene, rubber, leather,
cork
6.1.3

Possible causes of faults

The following causes may break the saw blade:
– If blade is tensioned too tightly or not tightly enough
– Mechanical overloading of the blade by feeding too quickly.
– Bending or twisting of the blade when turning the work piece too quick-
ly when cutting curves.
– When the wear limit of the saw blade has been reached.
– If the screws are tightened on saw blades with cross pin.
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