Thread: Orbital Jigsaw Action - how much forward and backward is normal ?

Hi and welcome.

I suppose you are talking about the blade movement back against the roller guide not the reciprocating motion.

The blade should be resting on the roller guide and the roller guide should not be pushing the blade forward.

Forward movement is nothing to worry about although more than 1 to 2 mm would be disconcerting for me.

Yup, all your assumptions are correct, I just expected more 'orbital' movement, at least visibly. Upon reflection, yes say 10mm forward and back motion would be a scary thing to control, especially with cutting curves.

That being said, how does one really know that the orbital mode is operating as it should? Eye balling it yeilds only the minimal change I've already mentioned. Cutting ease is not so easy to determine as I'm not used to the tool in the first place...

So I guess my question is: I should be expecting a minimal visible change in the blade movement between modes? (2mm too much even)

Got a Metabo with 4 levels or orbit, max is about 2-3mm movement.

You should be able to see the difference from all the way off, to all the way on and you'll definitely feel it in chipboard and ply.

Hi all,

if memory serves me correctly, the guide wheel pushes the blade a bit forward during the upward sawing stroke, to achieve a more "bite" into the material, and to give the blade a bit more frictionfree play during the non-sawing down stroke, provided the user doesn't push the machine forward too forcefully. The advanced forward movement during sawing and vertical downstroke without forward movement also helps the blade to release the dust between the teeth in a better way. Before orbital jig saw systems were built, Bosch, Makita and a few other tried to achieve the same through blades with a "progressive" cut, meaning the row of teeth was not vertical straight but tilted forward a bit towards the tip, giving a slight forward cutting motion of the teeth row at each up-stroke and a slight friction and dust releasing effect at each down-stroke.

The working of an orbital mechanism is well illustrated in the exploded view of the Bosch 1581 blue jig saw. The gear wheel 15, which drives the excenter piece 28 (which drives the blade rod 43 up and down) also has a cylindrical shape at the front that drives the counterweight 22 up and down, to cancel out machine vibration. In orbital jig saws, the drive fork 18 is added. The fork is moved left and right, with a guiding axle at the bottom being its pivot point of movement. This makes a tooth (red arrow) move up and down. This tooth presses down on the lever part (green arrow) of the guide wheel 54, which pushes the saw blade forward when the machine is in orbital mode. The adjusting lever 35 determines the offset of the movement. In setting 0 the tooth has no influence on the guide wheel lever and in setting III the effect of the tooth on the lever is maximal, giving approx.1.5 to 2 mms forward motion to the guide wheel. At the blade's tip this is visible as some 8 mms forward motion with a standard length blade. Because the fork is moved by an excenter shape it moves in a smooth way back and forth and not in a sharp zig-zag fashion. Therefore the blade also moves in an elliptical way and not straight down and somewhat tilted straight up. That's why the movement is called "orbital".

In order to enable the guide wheel to push the blade forward during upward motion, it is necessary for the entire rod array, including its bearings and drive clamp, to accept a certain degree of tilting without anything getting pinched or wrecked by friction. The rod's bottom bush bearing 172 (orange arrow) is free to move forward and back somewhat within the drive housing and both bottom bearing 172 and top bearing 171 can accept one or two degrees of rotation to avoid quick wear and rod pinching. The drive excenter 28 moves the rod up and down through pin 24 that takes bearing 30 and its outer bush 31. Bush 31 fits clamp 48 (purple arrow), that is attached to the blade rod. This clamp must also allow one or two degrees of tilting around bush 31, which is not a mechanical ideal situation. In practice this boils down to a minimal but necessary amount of play between clamp and bush, which must never get too big because quick part wear and rattling sound would be the result. The grade of accepting a certain deviation of the perfect vertical up and down movement is the true limiting factor of the amount of forward motion that an orbital jog saw can offer to the saw blade. I don't think that could ever be more than a few mms for a jig saw system of this size.

greetings

gerhard