Fitting a new motor on the Clarkson Mark1 - Single Phase






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I had a problem with the windings in the original 3 phase motor and it would not work with my VFD unit.
A few years ago I bought a single phase motor for 20 pounds on ebay. As a temporary measure to keep the machine up and running I fitted the new single phase motor to a wooden plate and then fixed the wooden plate to the existing motor mount fixings. This avoided altering the existing Clarkson motor mount fittings. This all worked fine but the old belt eventually wore out. I got a new belt which was about 1.5 inches shorter than the old belt. I could not adjust the motor position to accomodate the new belt because of the thickness of the wooden plate. Hence, it was time to redo the motor mounting properly.


↓ The original 3 phase motor was fitted to two horizontal bars.
The motor position is altered by adjusting the position of the four lugs that secure the two horizontal bars.
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↓ Here is the temporary wooden plate that is being replaced here.
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↓ I wanted to keep the original mounting bars in their original condition so I decided to replace the two bars with an aluminium plate, and fit the single phase motor to the new aluminium plate.
I cut the aluminium plate to size in the bandsaw.
I pushed the plate against the lathe chuck to align it square, then I clamped it up ready for milling.
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I milled the edges to clean them up.
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↓ There was a nasty looking slot in the plate that looked like it was hacked out with a chisel and various sized drills.
Although it would not be seen I just had to tidy it up.
This is the state of the slot before machining.
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The slot after machining. Aah, that's better, not perfect, but much better.
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↓ Here is the finished motor mounting plate. I may paint it sometime.
I drilled and tapped four holes in the sides of the plate to accept M8 bolts.
The four vertical M6 bolts will secure the motor to the plate.
The slot and the four empty holes are not used and were already on the scrap plate.
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↓ Here are the original adjusting lugs.
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↓ The plate is fitted to the adjusting lugs.
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↓ The motor is fitted to the plate.
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↓ The new belt is tensioned by correctly positioning the motor plate in the slots of the four adjusting lugs.
The milled edge of the plate looks nice.
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↓ The bore in the Clarkson pulley did not match the diameter of the shaft on the new motor, so I had to make a sleeve to fit the pulley on the shaft.
The Clarkson pulley does not have a keyway.
The sleeve fits over the motor shaft and fits inside the pulley.
I drilled a hole in the sleeve. The 1/4inch BSW bolt on the pulley passes through the hole in the sleeve and locates on the bottom of the keyway. It works fine.
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↓ Here is the new belt.
I bought the belt off ebay for 25 pounds. It was a bit pricey for my liking but I bit the bullet and decided to give it a try.
The belt is made from a 'stretchy rubber' type of material. It is perfectly smooth on one side and rough on the other. I fitted the smooth side on the pulleys.
I have not put too much tension on the belt.
It always amazes me how these flat belts centre themselves on the crown of the pulleys when the machine is running.
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Here is the rough side of the new belt.
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The new belt is about 1.5 inches shorter than the old belt.
After adjusting the motor position and setting up the distance between the two pulleys to accomodate the new belt, I slipped off the new belt and temporarily slipped on the old belt.
This picture shows the old belt and the difference in size between the belts.
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The single phase wiring is a very simple affair.
The LNE (Live Neutral and Earth) electrical supply is from a standard household 13 amp plug.
The LNE electrical supply goes to a 13 amp switched fused spur. The motor draws around 4 amps so the switch is ok for this light domestic use.
I ran the LNE to the 'supply' side of the switched fused spur. The LNE 'load' output from the switch goes to the motor.
A permanent LNE supply is taken off the 'supply' side of the switch, and goes to the Mem Light. The switch on the Mem Light controls the light.
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↓ I fixed a junction box on the underside of the motor.
The motor plate was in the way so I refixed it to the top of the motor using two M4 pan head screws.
By the way, I had problems with this single phase motor from when I first installed it a few years ago. It has always been very noisy and just did not sound right.
This time round I stripped the motor and found that the bearings were too tight. I replaced both bearings with some old used washing machine motor bearings I had lying around. I also cleaned out and lightly greased the capacitor starting gear. The motor sounds so much better, and now appears to have a soft start which was not there before.
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↓ I tapped two lugs on the motor. The junction box will be fixed to these lugs.
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↓ The metal junction box is secured to the underside of the motor with two M4 screws.
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↓ The conduit for the Mem Light is connected to the junction box.
Here is the Mem conduit going down from the Mem Light to the junction box below.
The conduit is the original metal conduit.
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↓ Here is the Mem conduit entering the junction box on the underside of the motor.
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↓ The motor feed conduit is connected to the junction box.
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↓ I bought the plastic conduit and fittings from Maplins.
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↓ The power feed conduit is connected to the junction box.
In this picture you can see the power feed conduit on the left, the motor feed conduit in the middle, and the Mem conduit on the right.
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↓ The power feed conduit is routed through a hole in the top of the bench.
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↓ Here is the finished job.
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