Rapidor hacksaw

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Adrian Godwin

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Mar 21, 2005, 5:42:06 PM3/21/05
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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

mike.cr...@virgin.net

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Mar 21, 2005, 6:13:27 PM3/21/05
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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

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Mar 21, 2005, 7:07:47 PM3/21/05
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mike.cr...@virgin.net wrote:
>
> 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 ?

> 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

mike.cr...@virgin.net

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Mar 22, 2005, 2:15:24 PM3/22/05
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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

Adrian Godwin

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Mar 22, 2005, 7:34:04 PM3/22/05
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Roland and Celia Craven <rol...@petternut.co.uk> wrote:
> 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

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Mar 22, 2005, 6:13:19 AM3/22/05
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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
pre...@easynet.co.uk
http://www.prepair.co.uk

Adrian Godwin

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Mar 22, 2005, 7:52:06 AM3/22/05
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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 ? :-)

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

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Mar 22, 2005, 8:25:11 AM3/22/05
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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
rol...@petternut.co.uk
http://www.petternut.co.uk

"Adrian Godwin" <adrian...@ntlworld.com> wrote in message
news:m0h5h2-...@smaug.toynbee.org.uk...

Prepair Ltd

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Mar 22, 2005, 8:38:33 AM3/22/05
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On Tue, 22 Mar 2005 12:52:06 +0000, Adrian Godwin
<adrian...@ntlworld.com> wrote:

>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 ? :-)
>
> http://www.oldengine.org/members/diesel/Ward/adcock.htm

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
pic.

>
>-adrian

Peter

Jez

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Mar 23, 2005, 2:19:58 PM3/23/05
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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

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Mar 23, 2005, 6:28:46 PM3/23/05
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Jez <inv...@invalid.invalid> wrote:

>
> 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

BigEgg

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Mar 25, 2005, 2:41:58 PM3/25/05
to

>>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

Stuart York

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Mar 11, 2018, 9:18:04 PM3/11/18
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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

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Mar 12, 2018, 6:47:42 AM3/12/18
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In article <fzkpC.181341$wa1....@fx22.am4>,
Stuart York <0f8503901d844703ee...@example.com> wrote:
> 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

--
alan....@argonet.co.uk
alan....@riscos.org
Using an ARMX6

Stuart York

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Mar 12, 2018, 9:18:04 PM3/12/18
to
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

miked.cr...@btinternet.com

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Mar 18, 2018, 6:08:12 AM3/18/18
to
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

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Mar 27, 2018, 1:53:47 AM3/27/18
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On 12/03/2018 02:18, Stuart York wrote:
> 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?


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.

Peter Noden

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Jul 26, 2020, 6:18:03 PM7/26/20
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replying to Adrian Godwin, Peter Noden wrote:
Hi Adrian fellow Rapidor restorer. I have just finished what I believe is a
1952 Rapidor Manchester Hacksaw with the same similar issues your having. I
think the vice mechanism is how you see it. Mine is exactly the same. No pin
to hold it from coming out of the release jaw, but at the very back of the
lose jaw on mine there is a screw hole but whether that held a plate or
somethings to be guided on the threaded bar. I don't know, there is no sign of
it on the machine when I was taking it apart. The piston you described is
exactly the same as mine. What the little bar does on the side Once again I
do not know. The only thing I can think of is that it could of operated a
water cooling pump. On the older versions its got a lit cover on it and shaft
is free to move through it but no sign of a water pump. The code number how
ever I think mine is 3mx or something but after that all in the same line its
got 1952 . So 3MX1952 and that's all I have to go on with regards to its age.
This machine looks great. I have painted it with a dark green Japlin colour
and a red wheel in memory of Frank Hornby, Meccano. The main Cam is perfect
with no ware on it so again I cant comment on that. The problems I have had is
the motor was Three phase so I have fitted it with a single now. I have one
last problem and that the release handle with the looking handle I am not sure
how the spring mechanism works I cant find any literature on or with regards
to the machine specification at all. There's is lots of lovely Youtube videos
on seeing them operational which is great, but not much use when you are
restoring them. Only other issue it heavy ha ha. If you know of any literature
with regards to the spring mechanisms I would greatly appreciate it.
Good luck Adrian hope it all works well.
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