It's in surprisingly good condition under the dirt and leaves (nothing
really seized up) but I'm confused about the dashpot mechanism.
The dashpot itself is straightforward - a piston with holes in it, and
a spring-loaded washer to shut the holes as the piston is pushed into
the dashpot. But there's a length of 1/4" rod screwed into the piston
that runs parallel to the square shaft. It's about 6" long, has a
short knurled length, then just stops, bent and ragged.
The main cam that drives the saw also has some wear, as though a
cam-follower once rode on it. There's an empty boss in the base
casting, directly under the edge of this cam. I suspect there's
something missing here, perhaps a hydraulic lifter that's connected
in some way with that 1/4" rod. Anyone know how it's supposed to
work ? It's a long while since I last used a well-maintained one.
Another puzzle is the vice : when it's tightened, the jaws are pulled
together nicely. But when the crank is loosened, the thread doesn't
drive the jaws apart : instead, the crank winds out of the front jaw
and a tap on the end is needed to move the jaws apart. Is this right,
or should there be a pin somewhere to keep the crank in place ?
I have a Rapidor Major in very good condition, and what you describe
sounds similar to my saw.
On the Major the blade is angled with respect to the motion of the
slide, so that the cutting pressure is maintained as the blade moves
forwards. i.e. the frame tends to lift as it moves forward and the
blade rides over the work. On the return stroke the descent of the
frame is delayed by the action of the dashpot, so the blade is held out
of cut. The knurled rod in the dashpot presses against the piston
plate, and allows adjustment of the damping rate to suit the speed of
cutting. There is no mechanical link between the drive mechanism and
the dashpot (though there is a simple prop to hold the frame lifted
clear when not in use).
The vice on my Major works exactly as you describe.
Hope this helps
OK, I can see how that would work. I presume the dashpot should have
oil in it, not just air - if so, how thick should it be ?
However, there's certainly a line of less muck on the edge of the
cam. I'm glad I haven't got to build a master cylinder for it, but I
wonder what's caused it ? Nothing else appears to rub there, and the boss
below doesn't have any obvious function (there are other holes for
mounting and draining). Maybe a cam-operated suds pump ?
> There is no mechanical link between the drive mechanism and
> the dashpot (though there is a simple prop to hold the frame lifted
> clear when not in use).
> The vice on my Major works exactly as you describe.
> Hope this helps
Yes, I've got the prop too.
I use ordinary 30 grade oil in the dashpot, and it seems to give a
sensible range of damping adjustment.
-can't help on the cam you mention. I guess you must have a different
model of saw to mine. My suds pump is buried in the base of the unit,
and is chain driven
Possibly not the same as mine, then - the base casting has a wall just
behind the dashpot, and the hole I mean is behind that, only a few
inches from the back. This area would tend to collect spilled oil from
the mechanism, so is best kept apart from the suds. The coolant
couldn't drain to there without also flowing onto the floor. The boss
might well be part of a pipe fitting, but I haven't taken it apart
There is, however, another hole just in front of the dashpot :
this would drain fine. But on my model, it doesn't have any
sort of fitting.
This machine looks as though it was n production for a long
while - there must be a lot of variations about, especially
in such things as motor mount and coolant pumps.
The one at the bottom of this page ? :-)
That's pretty well identical, though I wasn't sure of the size.
Except yours has a weight, stand, motor, and has had a lot more
elbow grease applied !
I think Mike's sorted out my biggest problem, but a pic of the top
of the dashpot would still be interesting, thanks. And do you have
a boss (or even just a hole) in the tray directly underneath the
cam / flywheel ?
"Adrian Godwin" <adrian...@ntlworld.com> wrote in message
>Prepair Ltd <pre...@easynet.co.uk> wrote:
>> We also have a 14" blade Rapidor, we can do some pic's of specific
>> items if you need them. Our vice also does that!
>The one at the bottom of this page ? :-)
Yup, that's the one.
>That's pretty well identical, though I wasn't sure of the size.
>Except yours has a weight, stand, motor, and has had a lot more
>elbow grease applied !
Mad Mick Mills did the work, I bought it from him after he had been
over it and sorted it out.
>I think Mike's sorted out my biggest problem, but a pic of the top
>of the dashpot would still be interesting, thanks. And do you have
>a boss (or even just a hole) in the tray directly underneath the
>cam / flywheel ?
See Roly's reply, but I will check mine as well tonight and take a
The boss in the base under the cam is for a suds pump. Mine is
I can take some pictures of it if you like - let me know...
> The boss in the base under the cam is for a suds pump. Mine is
> currently siezed...
> I can take some pictures of it if you like - let me know...
Yes please !
Or even just a written description - I can imagine a spring
plunger and valve arrangement but approximate dimensions
would be interesting.
I was given a machine vice which had the same problem - there was a slot
on the threaded rod, just inside the casing, which I think should have
had a circlip on it (or something).
I couldn't get a circlip on (not enough clearance for pliers) so I
wrapped a couple of turns of thin wire into the groove. It's worked OK
for a couple of years now.