Author Topic: Pedrazzoli Cold Saw (VERY STRONG) Return Spring Replacement  (Read 486 times)

Offline awemawson

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Pedrazzoli Cold Saw (VERY STRONG) Return Spring Replacement
« on: April 30, 2020, 10:43:53 AM »
My Pedrazzoli cold saw has given me sterling service - I wouldn't be without it. But the other day while chopping the heavy box tubing for the new Chiller unit the tension spring that holds the motor up broke and went pinging about in the welding shop bouncing off everything including the roof.

Now this is a VERY stout spring - about 35 mm O/D and wound from 20 turns of 5.75 mm spring wire it takes a lot of pulling to stretch it even a few mm. It has previously broken, and I've heated the end turn and re-formed a hook, but it's never been 100% satisfactory. Then I had no choice as I couldn't find a replacement, but now, with the power of Google I tracked one down. Stupidly expensive for a bit of coiled wire but that how things are these days !

It arrived today - so fit it - another 5 minute job. The spring hooks into a hole in a cast lug in the swivel mechanism and a bolted on lug on the motor itself, and needs stretching 25 mm and simultaneously one of the hooks turning 90 degrees to go in the hole. Now this just wasn't going to happen - try as I might with levers, Mole grips, and goodness knows what I drew a blank.

So what happens if I unbolt the bracket on the motor, hook the spring on and re-fit the two screws in the bracket? Well the spring still  needs stretching an inch while you put the screws in so that's not happening!

How do you temporarily stretch a tension spring such that it stays longer while you fit it, but can return to it's natural length when fitted. Answer: WEDGES  :thumbup:

Using an assortment of chuck wedges and bits of metal I inserted them between the coils slowly elongating the spring. When long enough I screwed the bracket back and the act of pulling the saw down and stretching the spring allowed me to remove all the wedges.

. . . job done  and no fingers lost  :clap:
Andrew Mawson
East Sussex

Offline John Rudd

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Re: Pedrazzoli Cold Saw (VERY STRONG) Return Spring Replacement
« Reply #1 on: April 30, 2020, 11:23:41 AM »
Nice job... :bow:
'Necessity is the mother of invention'.... but you already know that.. :beer:
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Offline NormanV

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Re: Pedrazzoli Cold Saw (VERY STRONG) Return Spring Replacement
« Reply #2 on: April 30, 2020, 01:04:02 PM »
How did the manufacturers do it? I am sure that they didn't do it your way. (as Frank would have sung)

Offline awemawson

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Re: Pedrazzoli Cold Saw (VERY STRONG) Return Spring Replacement
« Reply #3 on: April 30, 2020, 01:34:00 PM »
Probably Desperate Dan was still working for them, and having his Cow Pies for lunch  :lol:
Andrew Mawson
East Sussex

Offline Will_D

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Re: Pedrazzoli Cold Saw (VERY STRONG) Return Spring Replacement
« Reply #4 on: April 30, 2020, 05:35:09 PM »
Probably Desperate Dan was still working for them, and having his Cow Pies for lunch  :lol:
Aunt Agie is still my favourite baker of Cow Pie
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Offline WeldingRod

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Re: Pedrazzoli Cold Saw (VERY STRONG) Return Spring Replacement
« Reply #5 on: May 01, 2020, 02:32:54 PM »
Ah, I see chuck wedges!  I've only Used mine for a chuck twice... far more on other stuff ;-)

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Offline awemawson

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Re: Pedrazzoli Cold Saw (VERY STRONG) Return Spring Replacement
« Reply #6 on: May 01, 2020, 03:36:52 PM »
Mine were last used when they came to the aid of a plumber who couldn't get a tap handle off. He was amazed and demanded to know where he could get some  :clap:
Andrew Mawson
East Sussex