SAWING MACHINES
DURING MY APPRENTICESHIP, IT WAS ALWAYS FASCINATING TO SEE A BATTERY OF DONKEY SAWS IN OPERATION. MANY OF THESE SAWS WERE OF THE MARQUE "RAPIDOR" WHICH WERE MADE IN MANCHESTER. THESE RAPIDOR SAWS HAVE THE ADVANTAGE FOR US THAT THEY CAN EASILY BE DISMANTLED FOR TRANSPORTATION AND ARE CHEAP TO BUY.
ABOVE YOU CAN SEE MY PARTIALLY DISMANTLED RAPIDOR SAW. i ORIGINALLY IMPORTED THIS INTO NORWAY ABOUT TWENTY YEARS AGO AND IT`S THE SOLE SURVIVOR OF MY ORIGINAL WORKSHOP IN OSLO THAT HAD TO BE SOLD OFF AS THE BUILDING WAS UNDERGOING A CHANGE OF USE. IT`S NOW A HUGE STORAGE COMPLEX THAT HIRES OUT SMALL UNITS FOR DOMESTIC STORAGE. I LENT THIS SAW TO A FRIEND AND A FEW YEARS LATER TOOK IT TO MY WORKSHOP AT THE FRENCH HOUSE. THEN WHEN I STARTED UP MY WORKSHOP IN NORWAY AGAIN I RE IMPORTED IT BACK TO NORWAY.
I HAD BOUGHT ANOTHER SAW ON EBAY FOR THE FRENCH WORKSHOP. PHOTOGRAPHS CAN BE MISLEADING AND WHEN I WENT TO PICK UP THIS SAW I DISCOVERED IT WAS THE SIZE OF A SMALL HOUSE! WHEN THIS WAS INSTALLED IN THE FRENCH WORKSHOP, I DISMANTLED THE RAPIDOR SO THAT IT COULD BE TRANSPORTED BACK TO NORWAY. TWO YEARS LATER I WAS ABLE TO PACK IT INTO MY FAITHFUL BERLINGO AND TOOK IT THERE.
I HAD BOUGHT ANOTHER SAW ON EBAY FOR THE FRENCH WORKSHOP. PHOTOGRAPHS CAN BE MISLEADING AND WHEN I WENT TO PICK UP THIS SAW I DISCOVERED IT WAS THE SIZE OF A SMALL HOUSE! WHEN THIS WAS INSTALLED IN THE FRENCH WORKSHOP, I DISMANTLED THE RAPIDOR SO THAT IT COULD BE TRANSPORTED BACK TO NORWAY. TWO YEARS LATER I WAS ABLE TO PACK IT INTO MY FAITHFUL BERLINGO AND TOOK IT THERE.
ABOVE, A VIEW OF THE MOTOR. THIS IS A SPECIAL GEARED MOTOR THAT REDUCES THE RPM AT THE DRIVING END TO 1/3 OF THE MOTOR SPEED AND WAS FITTED TO VERY FEW OF THE LIGHT RAPIDOR SAWS, ACCORDING TO THE ARTICLE ON LATHES.CO.UK.
WHEN I LOOKED AT THE MOTOR MORE CLOSELY I DISCOVERED THAT IT WAS A 415 VOLT THREE PHASE BUT NOT A DUAL VOLTAGE ONE AND I NEEDED TO CONVERT IT TO 240 VOLT THREE PHASE TO SUIT THE SUPPLY AT MY NEW WORKSHOP. ALL THREE PHASE 415 VOLT MOTORS THAT ARE MANUFACTURED AS SINGLE VOLTAGE MOTORS CAN BE MADE TO OPERATE ON 240 VOLTS IT`S SIMPLE BUT VERY SKILLED WORK. THE ENDS OF THE FIELD WINDINGS HAVE TO BE FOUND AND CHANGED OVER. THE PROBLEM IS THAT THESE FIELD WINDING ENDS ARE BURIED UNDER THE INSULATION THAT COVERS THE WINDINGS AND REQUIRE CAREFUL INVESTIGATION TO FIND THEM WITHOUT DAMAGING THE FIELD WINDINGS THEMSELVES.
HAPPILY MY ELECTRICIAN FRIEND IN OSLO OFFERED TO DO THIS FOR ME AND MADE A NICE JOB OF IT.
DURING THE TWO YEARS THAT THE SAW HAD BEEN DISMANTLED SOME OF THE PARTS FOR MOUNTING THE MOTOR MAY HAVE BEEN LOST OR MY MEMORY OF HOW IT WAS MOUNTED WAS FAULTY. USING THE DRIVE BELT AS A GUIDE TO THE POSITION OF THE MOTOR, I ARRIVED AT THE CONFIGURATION SHOWN ABOVE. THE PIECE OF WOOD WAS ADDED TO PREVENT VIBRATION OF THE MOTOR FATIGUING THE CAST IRON MOUNTING PLATE AROUND THE MOUNTING HOLES. NOT GOOD ENGINEERING PRACTICE BUT A PRAGMATIC SOLUTION TO THE PROBLEM WITHOUT TIME CONSUMING MODIFICATIONS.
HAPPILY MY ELECTRICIAN FRIEND IN OSLO OFFERED TO DO THIS FOR ME AND MADE A NICE JOB OF IT.
DURING THE TWO YEARS THAT THE SAW HAD BEEN DISMANTLED SOME OF THE PARTS FOR MOUNTING THE MOTOR MAY HAVE BEEN LOST OR MY MEMORY OF HOW IT WAS MOUNTED WAS FAULTY. USING THE DRIVE BELT AS A GUIDE TO THE POSITION OF THE MOTOR, I ARRIVED AT THE CONFIGURATION SHOWN ABOVE. THE PIECE OF WOOD WAS ADDED TO PREVENT VIBRATION OF THE MOTOR FATIGUING THE CAST IRON MOUNTING PLATE AROUND THE MOUNTING HOLES. NOT GOOD ENGINEERING PRACTICE BUT A PRAGMATIC SOLUTION TO THE PROBLEM WITHOUT TIME CONSUMING MODIFICATIONS.
THE NEXT HURDLE WAS TO FIND A 240 VOLT COIL FOR THE CONTACTOR. I LIKE THE ORIGINAL CRABTREE CONTACTOR AND IT`S NICE STEEL BOX AND RATHER THAN INSTALL ONE OF THOSE MODERN PLASTIC ONES I TRIED EBAY TO FIND THE COIL. I EVENTUALLY FOUND A SOURCE IN THE UK AND BOUGHT FOUR BUT THE DOWNSIDE WAS THAT THE POSTAGE COST AN ARM AND A LEG VIA UPS AND THEN THERE WAS THE IMPORT DUTY TO PAY AS WELL!
THE SAW NEEDED TO BE RE WIRED AS THE ONLY PLACE THAT I COULD FIND TO PARK IT WAS ON THE MEZZANINE PORTION OF THE WORKSHOP THAT IS 600 MM HIGHER THAN THE MAIN WORKSHOP AND DOES NOT HAVE PROPER HEADROOM. THIS MEANT THAT THE CONTACTOR WILL NEED TO BE MOUNTED ON THE FRONT OF THE MACHINE INSTEAD OF THE SIDE.
THE SAW NEEDED TO BE RE WIRED AS THE ONLY PLACE THAT I COULD FIND TO PARK IT WAS ON THE MEZZANINE PORTION OF THE WORKSHOP THAT IS 600 MM HIGHER THAN THE MAIN WORKSHOP AND DOES NOT HAVE PROPER HEADROOM. THIS MEANT THAT THE CONTACTOR WILL NEED TO BE MOUNTED ON THE FRONT OF THE MACHINE INSTEAD OF THE SIDE.
ABOVE, A BOX CONTAINING THE CRABTREE T16 CONTACTOR, THE COIL AND A MODERN CONTACTOR.
ABOVE, THE SWITCHBOX HAD TO BE RELOCATED TO THE FRONT OF THE MACHINE SO THAT IT CAN BE EASILY ACCESSED. I FOUND A PIECE OF ALLY PLATE IN THE SCRAP BOX AND DRILLED IT TO SUIT THE STIFFENING ROD HOLES SEEN ON THE LEFT HAND PHOTO AND THE CONTACTOR BOX MOUNTING HOLES. THE RIGHT HAND PHOTO SHOWS THE ASSEMBLY READY TO MOUNT ONTO THE SAW FRONT LEGS CASTING.
ABOVE A REASONABLY NEAT INSTALLATION. I PUT IN NEW CABLE GRIPPING INSERTS AS I DON`T LIKE THE METAL FLEXIBLE CONDUIT THAT WAS ORIGINALLY FITTED.
ABOVE, THE PHOTO SHOWS THE WORKINGS OF THE HYDRAULIC DOWN FEED FOR THE CUTTING ARM. THE RADIUSED PLUNGER THAT SLIDES UP AND DOWN THE CYLINDER, HAS HOLES DRILLED THROUGH IT TO ALLOW THE HYDRAULIC OIL TO PASS THROUGH. THE FLOW OF OIL IS ADJUSTED BY MEANS OF A SPRING LOADED PLATE POSITIONED UNDERNEATH THAT IS OPENED AND CLOSED BY THE SCREWED ROD, THUS CONTROLLING THE DOWNWARD MOVEMENT OF THE SAW ARM.
ABOVE LEFT, THE SAW ARM HAS BEEN PUT IN PLACE AND THE PLATE THAT KEEPS THE SQUARE RODS THAT SLIDE IN THE SWIVELING CASTING IN PLACE WILL BE ADJUSTED WHILE THE MACHINE IS OPERATING TO GIVE SMOOTH OPERATION TO THE ARM MOVEMENT. ABOVE RIGHT, THE VICE HAS BEEN ADDED BUT NOT FINALLY BOLTED DOWN UNTIL THE HANDLE HAS BEEN PUT BACK TO IT`S ORIGINAL CONFIGURATION. IT CAN HOLD WORK UP TO 6 INCHES (150mm) WIDE AND THE JAWS CAN BE ADJUSTED SO THAT A 45 DEGREE CUT CAN BE MADE.
ABOVE, THE MICRO SWITCH THAT CUTS OUT THE CURRENT TO THE MOTOR AT THE END OF THE CUT AND THE MOTOR HAVE BEEN WIRED UP. IN FACT THE WIRING ON THE SAW WAS COMPLETED BUT THERE WAS A PROBLEM WITH THE CONTACTOR NOT OPERATING. I THINK THAT THE MOVING PART OF THE IRON CONTACTS WAS SOMEHOW JAMMED, OR THE COIL ITSELF IS FAULTY. I WILL INVESTIGATE FURTHER NEXT TIME I`M IN THE WORKSHOP.
ABOVE, I REMOVED THE CONTACTOR FROM THE BOX AND DISMANTLED IT. THE ROOT OF THE PROBLEM WAS THAT I HAD RE-INSTALLED THE 415V COIL WHICH HAD JUST MADE A BUZZING NOISE LIKE AN ANGRY BEE AND DID NOT HAVE THE POWER TO PULL THE IRON CORE SO THAT THE CONTACTS WOULD NOT CLOSE. ALL THAT I HAD TO DO WAS TO INSERT THE 240V COIL AND WE WERE IN BUSINESS AGAIN!
I SUPPOSE THERE AREN`T SO MANY AMATEURS THAT TAKE THEIR CONTACTORS APART AND I WAS PLEASED TO SEE A BEAUTIFUL PIECE OF PRECISION ELECTRO MECHANICAL DESIGN. THESE CONTACTORS FROM THE 50`S ARE EXTREMELY RELIABLE AND HOW IT WORKS IS A CLEVER PIECE OF DESIGN. THERE ARE SOME SMALL PARTS AND SPRINGS THAT CAN BE LOST IF ONE IS NOT CAREFUL TO DISMANTLE IT ABOVE A TRAY THAT WILL CATCH ANY STRAY PARTS THAT FALL OUT THAT CAN BE LOST ON THE FLOOR.
THE PRINCIPLE IS THAT THE SOLENOID COIL THAT CAN BE SEEN IN THE LEFT OF THE UPPER RIGHT HAND PHOTO, WHEN ENERGISED, PULLS THE IRON CORE THAT SLIDES IN THE CENTRE SO THAT THE CONTACTS THAT CAN BE SEEN ON THE RIGHT OF THE PHOTO COME TOGETHER WITH THE CONTACTS IN THE BODY OF THE CONTACTOR, THUS CONNECTING THE THREE PHASES TOGETHER SO THAT CURRENT IS SUPPLIED TO THE MOTOR.
THE CLEVER PART IS THAT THE 240V SUPPLY TO THE COIL FROM ONE OF THE PHASES IS JUST FOR THE INITIAL MOVEMENT OF THE CONTACTS, WHICH ARE SO ARRANGED THAT THE CURRENT NECESSARY FOR THE DURATION OF THE CONTACT IS SUPPLIED FROM THE DEDICATED CONTACTS WITHIN THE BODY OF THE CONTACTOR.
THIS IS A SAFETY FEATURE SO THAT IF THE ELECTRICAL SUPPLY IS HALTED FOR ANY REASON, THEN THE SPRINGS THAT ARE SITUATED BETWEEN THE COIL AND THE IRON CORE, ON THE DE-ENERGISATION OF THE COIL WILL PUSH THE CONTACTS APART. THIS PREVENTS THE MOTOR BEING ENERGISED WITHOUT PUSHING THE "ON" BUTTON AGAIN!
I SUPPOSE THERE AREN`T SO MANY AMATEURS THAT TAKE THEIR CONTACTORS APART AND I WAS PLEASED TO SEE A BEAUTIFUL PIECE OF PRECISION ELECTRO MECHANICAL DESIGN. THESE CONTACTORS FROM THE 50`S ARE EXTREMELY RELIABLE AND HOW IT WORKS IS A CLEVER PIECE OF DESIGN. THERE ARE SOME SMALL PARTS AND SPRINGS THAT CAN BE LOST IF ONE IS NOT CAREFUL TO DISMANTLE IT ABOVE A TRAY THAT WILL CATCH ANY STRAY PARTS THAT FALL OUT THAT CAN BE LOST ON THE FLOOR.
THE PRINCIPLE IS THAT THE SOLENOID COIL THAT CAN BE SEEN IN THE LEFT OF THE UPPER RIGHT HAND PHOTO, WHEN ENERGISED, PULLS THE IRON CORE THAT SLIDES IN THE CENTRE SO THAT THE CONTACTS THAT CAN BE SEEN ON THE RIGHT OF THE PHOTO COME TOGETHER WITH THE CONTACTS IN THE BODY OF THE CONTACTOR, THUS CONNECTING THE THREE PHASES TOGETHER SO THAT CURRENT IS SUPPLIED TO THE MOTOR.
THE CLEVER PART IS THAT THE 240V SUPPLY TO THE COIL FROM ONE OF THE PHASES IS JUST FOR THE INITIAL MOVEMENT OF THE CONTACTS, WHICH ARE SO ARRANGED THAT THE CURRENT NECESSARY FOR THE DURATION OF THE CONTACT IS SUPPLIED FROM THE DEDICATED CONTACTS WITHIN THE BODY OF THE CONTACTOR.
THIS IS A SAFETY FEATURE SO THAT IF THE ELECTRICAL SUPPLY IS HALTED FOR ANY REASON, THEN THE SPRINGS THAT ARE SITUATED BETWEEN THE COIL AND THE IRON CORE, ON THE DE-ENERGISATION OF THE COIL WILL PUSH THE CONTACTS APART. THIS PREVENTS THE MOTOR BEING ENERGISED WITHOUT PUSHING THE "ON" BUTTON AGAIN!
ABOVE LEFT, THE CONTACTOR BACK IN IT`S BOX AND WIRED UP AGAIN. ABOVE RIGHT THE FRONT OF THE BOX PUT BACK IN PLACE READY FOR USE. I`M HAPPY TO REPORT THAT UPON PUSHING THE START BUTTON THE CONTACTOR GAVE A NICE CLICK AND THE SAW MOTOR STARTED AS IT SHOULD.
IN PROGRESS