Repair Spin Mop or Magic Mop

14 December 2010

IntroductionMagic mop or 360 degree mop are spin mops. The earlier model has a foot pedal with gearing system that will spin the cage as the pedal is being “pumped”. This article will describe how to repair this kind of spin mop.





How Spin Mop works?The spin mop has a set of gearing system. When the pedal is stepped on, it will spin the centrifugal cage. The heart of the system is a “one way bearing” that allow the force to be transmit to the shaft of the centrifugal cage.

This bearing has about 8 small little needle bearings in it that are arranged to “lock” the gear to the shaft whenever a force is applied to turn the gear. As soon as the force is removed or when one stops the pedal “pumping”, the needle bearings will “unlock” themselves, allowing the centrifugal cage to continue spinning freely with the “one way bearing” now acting as a normal bearing. The animation of the “one way bearing” can be found here


What Can Go Wrong?
After some use, these little needle bearings will wear out and no longer able to “lock” the gearing system to the shaft of the centrifugal cage. The centrifugal cage will stop spinning.

What can be done?a) Dismantle the gearing mechanism

1. Unscrew the 4 screws that attach the gearing block from the pail

2. Remove the small pinion gear that is attached to the shaft



3. Remove the "one way bearing" by knocking the old one out




4. Replace the “one way bearing”. Check to rotate the shaft by hand to ensure the correct direction of the bearing before inserting the bearing. The “one way bearing” will not work if it is inserted in the wrong direction.  It may be necessary to put the bearing back on to the shaft to test the rotation just to be sure.
5. Re-assemble the gearing block.

After Note:

How to remove the Bearing from its Housing

First remove as many old bearing needles from the housing using a small watch screw driver as shown

then put the gear over the vice with a gap that will allow the old bearing to be knock out lightly  using a small screw driver and a hammer,  aiming at the rim of the bearing housing space left over by the needle bearings.   When the bearing is on its way out,  grip it by the vice.  A twisting motion will remove the bearing.

How to Sharpen a Knife or Chopper

10 December 2010

Introduction
There are tons of articles and videos on the web telling people how to sharpen a knife or a chopper. Some are shown by professional chef. However, none could help a layman sharpening a knife or a chopper properly

Why?
The secret of sharpening a knife is to have the knife always maintaining at a constant angle of about 20 degree to the surface of the sharpening stone or sand paper when sharpening a knife. If the knife edge is irregular, the knife will never be sharp.

How?
To maintain a constant angle, one can use something like a thicker steel ruler to provide a shim or a spacer to “wedge” the knife at about 20 degree angle to the surface of the stone. The trick is on how to stick the ruler to the knife while sharpening the knife.

A Simple Method
a) Find a piece of PVC electrical trunking about the length of the knife. One may be able to get one free from the electricians as they often have some waste piece lying around in the work places; the PVC trunking will usually have a "tongue and groove" arrangement to snap the cover in place;

b) Remove the cover of the PVC trunking which should have a “groove” in it. Cut the “groove” piece out of the cover and snap the piece to the knife as shown.

c) Start sharpening and one will always have a knife or a chopper sharpened in a professional way.

How to Sharpen a Planer Blade

8 November 2010

Introduction
There are many ways to sharpen a planer blade instead of replacing and throwing them away. This article will introduce one easy way.

The Planer and Planer Blades
The planer used is as shown. It has 2 blades, each has a length of 3-1/4" and are made of HSS steel.




When the blades are blunt, it will not give a good cutting surface on the wood and the surface will have a fluffy feeling.
The Sharpening Tools
The usual way to sharpen the blade is to use a standard blade sharpening tool which has adjusting screws for angle and other adjustments. Grinding stones are often used. The sharpening work will require some professional skill to prepare grinding stones etc. This article will introduce a simple and yet effective way for DIYs using tools that can be made in just less than ½ hour. No professional skill really required.

The Materials
a) A base made from a piece of plywood measuring around 100 mm x 75 mm ( 4” x 3”) or with the width to suit the length of the blade;
b) A 15 mm PVC tube of about 75 mm (3”) in length;
c) 4 wood screws and washers; 2 shorter ones to tighten the blade to the base and 2 longer ones to tighten to the base to a PVC tube for adjustment of the blade angle;
d) 2 pieces of water base sand papers; one of 240 grade and the other of 300 grade or finer
e) Optional: a set of rollers to be mounted underneath the 15 mm PVC tube so that the base can slide freely on the sand papers. One can use the small rollers that is stripped from the spoilt computer mouse for this purpose.

Other tools required are electric drills and suitable drill bits

The Set Up
a) Drill 2 rows of holes and 2 small holes as shown on the base
b) Drill 2 small holes on the PVC tube to hold the longer screws


The Completed Assembly



Note:
1. One can omit having rollers mounting beneath the PVC if one can always place the PVC tube outside the sand paper area. Anyway, PVC tube are replaceable if they are worn.
2. Constantly check the grinding surface of the blade and adjust the angle of the blade to be grinded. When the angle is correct, make a marking on the PVC tube and the base.
3. When the blade is ready, one should feel the blurs on the opposite edge of the blade. Dismantle the blade and grind away the blur on a fine sand paper. To ensure the blade is always placed at a small angle to the sand paper, one can use a steel ruler or the back of another sand paper to "jack" up the opposite end of the blade when grinding away the blurs.