Discussion:
Rapidor hacksaw
(too old to reply)
Adrian Godwin
2005-03-21 22:42:06 UTC
Permalink
I'm repairing a Rapidor hacksaw that's been neglected for a few years.
I don't know what model it is, but the blade is 14" x 1" and several
of the castings have numbers like '3XM3' or '3XM4' on them.

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 ?


-adrian
m***@virgin.net
2005-03-21 23:13:27 UTC
Permalink
Post by Adrian Godwin
I'm repairing a Rapidor hacksaw that's been neglected for a few years.
I don't know what model it is, but the blade is 14" x 1" and several
of the castings have numbers like '3XM3' or '3XM4' on them.
It's in surprisingly good condition under the dirt and leaves
(nothing
Post by Adrian Godwin
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 ?
-adrian
Adrian

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

Mike
Adrian Godwin
2005-03-22 00:07:47 UTC
Permalink
Post by m***@virgin.net
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.
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 ?
Post by m***@virgin.net
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.

Thanks !

-adrian
m***@virgin.net
2005-03-22 19:15:24 UTC
Permalink
Adrian

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

Mike
Stuart York
2018-03-12 01:18:03 UTC
Permalink
replying to mike.crossfield, Stuart York wrote:
Hi.
I found your reply very useful. I also have aquire one of these lovely old
machines.
Forgive me for being thick, are you saying that the saw cuts on the forward
stroke?
Also, just below the top edge of the dash pot, there is a bent and mangled
bolt in mine. Any idea of its function?
Finally, any clue as to where I might fingers a parts diagram/manual?
Thanks in anticipation.
Stuart York.

--
for full context, visit https://www.polytechforum.com/modelengineering/rapidor-hacksaw-25405-.htm
Alan Dawes
2018-03-12 10:50:24 UTC
Permalink
replying to mike.crossfield, Stuart York wrote: Hi. I found your reply
very useful. I also have aquire one of these lovely old machines.
Forgive me for being thick, are you saying that the saw cuts on the
forward stroke?
Also, just below the top edge of the dash pot, there is a bent and
mangled bolt in mine. Any idea of its function?
Finally, any clue as to where I might fingers a parts diagram/manual?
Thanks in anticipation.
Stuart York.
I wonder if the information on the pages starting at:

http://www.lathes.co.uk/rapidor/

are of any help to you?

Alan
--
***@argonet.co.uk
***@riscos.org
Using an ARMX6
Stuart York
2018-03-13 01:18:02 UTC
Permalink
replying to Alan Dawes, Stuart York wrote:
Hi.
Thanks Alan, the site you mention has details of the Rapidor saw, they are
asking a lot of money, and I'm reluctant to purchase as there's no real
indication of the quality you get for your money. I was hoping a fellow
enthusiastic rebuild had a parts list/ diagram they might share.
Thanks for taking the time to reply.
Stuart

--
for full context, visit https://www.polytechforum.com/modelengineering/rapidor-hacksaw-25405-.htm
m***@btinternet.com
2018-03-18 10:08:11 UTC
Permalink
Stuart

As I explained in my original message, when properly adjusted the damper holds the blade out of cut on the back stroke. The blade must therefore be set in the frame so that the teeth cut on the forward stroke.

HTH

Mike
Brian Reay
2018-03-27 05:53:46 UTC
Permalink
Post by Stuart York
Hi.
I found your reply very useful. I also have aquire one of these lovely old
machines. Forgive me for being thick, are you saying that the saw cuts
on the forward
stroke?
Hacksaws normally do.

I remember my school metal work teacher having a funny demo to teach
this, along with using an initial 'back stroke' to mark the line of cut.

The Japanese use some pull saws in woodwork but I've not seen them in
metal saws.

Jigsaw blades cut on the up stroke but the blade is only supported at
one end.

Prepair Ltd
2005-03-22 11:13:19 UTC
Permalink
On Mon, 21 Mar 2005 22:42:06 +0000, Adrian Godwin
Post by Adrian Godwin
I'm repairing a Rapidor hacksaw that's been neglected for a few years.
I don't know what model it is, but the blade is 14" x 1" and several
of the castings have numbers like '3XM3' or '3XM4' on them.
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 ?
-adrian
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!


Peter
--
Peter A Forbes
Prepair Ltd, Luton, UK
***@easynet.co.uk
http://www.prepair.co.uk
Adrian Godwin
2005-03-22 12:52:06 UTC
Permalink
Post by Prepair Ltd
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 ? :-)

http://www.oldengine.org/members/diesel/Ward/adcock.htm

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
Roland and Celia Craven
2005-03-22 13:25:11 UTC
Permalink
Mine has such a hole. Since it had a pipe fitting screwed into it I assumed
it to be the coolant drain. Whatever; that's what it gets used for..
hth
--
Roland Craven
nr Exeter Devon, UK
***@petternut.co.uk
http://www.petternut.co.uk
Post by Adrian Godwin
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
2005-03-23 00:34:04 UTC
Permalink
Post by Roland and Celia Craven
Mine has such a hole. Since it had a pipe fitting screwed into it I assumed
it to be the coolant drain. Whatever; that's what it gets used for..
hth
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
yet.

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.

-adrian
Prepair Ltd
2005-03-22 13:38:33 UTC
Permalink
On Tue, 22 Mar 2005 12:52:06 +0000, Adrian Godwin
Post by Adrian Godwin
Post by Prepair Ltd
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 ? :-)
http://www.oldengine.org/members/diesel/Ward/adcock.htm
Yup, that's the one.
Post by Adrian Godwin
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.
Post by Adrian Godwin
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
pic.
Post by Adrian Godwin
-adrian
Peter

Peter
--
Peter A Forbes
Prepair Ltd, Luton, UK
***@easynet.co.uk
http://www.prepair.co.uk
BigEgg
2005-03-25 19:41:58 UTC
Permalink
Post by Prepair Ltd
Post by Adrian Godwin
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
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!
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.
--
BigEgg
Jez
2005-03-23 19:19:58 UTC
Permalink
Post by Adrian Godwin
I'm repairing a Rapidor hacksaw that's been neglected for a few years.
I don't know what model it is, but the blade is 14" x 1" and several
of the castings have numbers like '3XM3' or '3XM4' on them.
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 ?
-adrian
Hello Adrian,

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...


Cheers,

Jez.


jez[AT]jez[HYPHEN]nikki[DOT]net
Adrian Godwin
2005-03-23 23:28:46 UTC
Permalink
Post by Jez
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.

-adrian
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