Advice needed on Rapidor Saw

Thanks to Bob Minchin I have recently acquired a nice Rapidor Major power hacksaw at a bargain price (thanks again Bob).

However, having stripped and reassembled it, I'm now puzzling over how it is intended to operate. The key question is whether it should cut on the push or pull stroke.

I notice that the blade is set at an angle to the frame, so that it moves progessively lower as it moves forward. This means that the frame lifts as the blade rides across the workpiece. For this reason it seems to me that the blade should be set to cut on the push stroke, the oil-filled dash pot then holding the blade clear of the work piece on the pull stroke.

Against this, a book I have on machine tools says that power hacksaws all cut on the pull stroke, and as delivered the blade was fitted so as to cut in this direction. It also seems a good idea to cut with the blade in tension, rather than compression.

Can someone out there with a similar saw offer some advice? Thanks

Mike

Reply to
mike.crossfield
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I have a small Rapidor (16" hole-centres blade). It cuts on the push and the blade is maintained in constant tension by a thumb knob at the outer end of the cast frame, the adjusters then being tightened from the side. Your book is simply incorrect. hth

Reply to
Roland and Celia Craven

Mine is the slightly smaller one with an extra weight above the end of the hacksaw frame, but I am pretty sure it is the same as Roly's machine in terms of directional cut, but can go and have a look if you want a positive answer.

Peter

-- Peter & Rita Forbes Email Address: snipped-for-privacy@easynet.co.uk Web Pages for Engine Preservation:

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Reply to
Peter A Forbes

Gents, Whilst there may well be a preferred or correct way to put a blade into a particular powered hacksaw, the blade is always being pulled. The load on the teeth pull against the end fixing. Thus the end fixing pulls the blade. So the blade is not in compression. Having insufficient tension no doubt has all sorts of unwelcome effects though.

Occasionally the pedant in me shows!

Henry

Reply to
Dragon

Thanks (to both of you). Cutting on the push stroke did seem to make sense from the geometry of the machine, but I just wanted to check that I hadn't missed something.

Mike

Mike

Reply to
mike.crossfield

Henry the Dragon writes.............

Absolutely correct ! Well said.

Since the blade is effectively in tension in a frame between two pins it must be drawn by the leading one. There will be a clearance, however small, between the trailing pin and the hole in the blade, which prevents the blade being pushed from behind.

There is of course the argument that the blade is being pushed by the front pin!

Am I going too fast? :)

pin 'a' pushing the front of the blade pin 'b' merely maintaining tension

____________________________________________________________ ( < O>) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^ pin 'a' pin 'b'

Reply to
Mike Whittome

Reply to
Roland and Celia Craven

There is no Mechanical way to "pull" anytrhing as far as I know. Everything is "pushed" if you think about it!

Reply to
Chris R

Don't tell my winch that, I have enough problems as it is.

-- Regards,

John Stevenson Nottingham, England.

Reply to
John Stevenson

I don't think I can be bothered......

Reply to
Roland and Celia Craven

Perhaps a better diagram ...............

pin 'a' pushing the front of the blade pin 'b' merely maintaining tension

___________________________________________ ( < O>) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ pin 'a' pin 'b'

Reply to
Mike Whittome

Chris R said very succinctly ...............

Yep! Agree with that.

Reply to
Mike Whittome

Your blade is blunt

-- Regards,

John Stevenson Nottingham, England.

Reply to
John Stevenson

Thanks mike :-) but we do all know what is meant by "pulling" lol

Reply to
Chris R

Chris R writes ...............

So you have heard the rumours about the village tug-o-war team then!?

Reply to
Mike Whittome

John Stevenson accused me .............

That's because I've been cutting up trolls. :)

Mike

Reply to
Mike Whittome

In message , Chris R writes

When did you last see a Victorian china bog chain handle with "Push" writ large upon it?

HTH, HAND, TTFN :^)

Pete

Reply to
Peter Scales

The direction of the crank rotation can influence the action of the saw bow..

Tom

Reply to
Tom

Peter Scales writes ........

'Have a nice day' (thanks; you too), 'Tata for now', but WTBH is HTH.

I am sure I shall regret asking this question. :)

By the way it is the fingers which push down on the china handle, and the top link of the chain which pushes down on the cistern lever. Get it?

Cheers

Mike

Reply to
Mike Whittome

Hope This Helps, but YMMV.

Reply to
Airy R.Bean

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