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Archive for the ‘Simple solutions.’ Category

Simple solution No1.

To straighten a pin on a multi pin connector.

1. If you get a multi pin connector sent to you because someone has bent the pins be very careful, if you try to straighten them with a small pair of pliers or mosquito forceps you may get two problems,
1. The pliers may not be able to get in to where you want it without damaging the other pins.
2. You run the risk of snapping the pins.

This solution may not prevent the pins being snapped but it will reduce the possibility and will make getting to them really easy.

Find a piece of tube very slightly larger in diameter than the pin, try a hypodermic needle.
Slip it over the pin and bend it straight. Simple.


Simple solution, No2.

What to do about a broken rotameter tube.

I found this simple solution in a hospital in Pokhara in Nepal. The cyclopropane rotameter tube had obviously broken, without it gas would simply flow out and not get to the patient. The hole left by the broken tube was blocked with a glass vial. Cyclopropane is not used these days far less in a developing country so there was no need to replace it. Simple.

Improvised repair


Simple solution, No3.

A difficult to read pressure gauge because it is oscillating with pulses from the pump.

If you have a pump generating a flow of air in a plastic tube and you have a pressure gauge take off to monitor the pressure often you will find the pressure gauge needle oscillates with the pulses coming from the pump. Sometimes this can be quite extreme and it will make it difficult to read the correct pressure.

To cure this, remove the plastic tube from the pressure gauge. Find a brass wood screw that is just the right size to screw into the plastic tube. Put it in to a vice and cut off the head and with a file square off the end,  with a small metal saw cut a slot in the flattened top to take a screwdriver blade. Screw it into the tube deep enough so that you can re-attach the tube to the pressure gauge. Re-attach the tube to the gauge. The screw will slow down the air flow to the gauge because it has to flow through the screw’s spiral. This will dampen down the oscillations and reduce or stop the movement of the gauge needle. To dampen it even more use a machine screw instead and prepared in the same way. You may find this may dampens the flow too much.


Simple solution. No4.

Anti kink solution for plastic pipes.

Some times you will have a plastic tube that has to make a fairly sharp bend so it fits into a tight situation. The problem may be that in doing so the tube develops a kink reducing the flow of gas or liquids. To prevent this happening find a spiral spring that is just the size to slide into the tube. Slide it into the tube so that it rests where the bend is. This will stop it kinking.


Simple solution. No5.

Need a small spring?

From time to time you may need a small spring and not be able to buy one, here I am thinking of a spring that is 10mm or less in diameter, though you can make larger ones.

What you need. A length of small diameter spring steel wire, you can get an idea of the diameter by looking at and measuring the wire in a spring of a similar size. A normal drill half the size of the final diameter of the spring you need. So if you need a spring with an outside diameter of say 10mm you will need a 5mm drill.

You will need a lathe or an electric drill. Put the drill into the chuck of the lathe or electric drill and before you tighten the chuck take your spring wire and secure one end in the chuck with the drill. Now with the chuck revolving at the very lowest speed and turning away from you and your hand held steadily allow the wire to be drawn on to the revolving drill, guide it on so that it is kept tightly together like an extension spring, see below, yours will not have to loops on the end when you have finished , you can put them on afterwards if you need to.torsion continue on until you have wound on a length a little more than you need.

Stop the lathe, undo the chuck and release the wire that is now in spiral shape of your spring. Cut each end with wire cutters to create the length and end style you want.

You can also make torsion springs, it is only the way you finish off the ends

torsionspr

The thicker the wire the stronger the spring. There is a limit to the thickness of wire you can use making springs this way.


Simple solution, No5.

Acrylic, cutting, drilling, polishing and glueing.

Acrylic sheet is sometimes called Perspex, Perspex is a trade name.

If you need to cut new acrylic leave the protective plastic on it to keep the finish and only peel it off afterwards.

It can be cut with a bandsaw but do keep the speed as high as you can and use a very fine blade, do not force the acrylic through, it can overheat and it may melt and lock up the blade. If necessary put some water on it to keep it cool.

The same applies to drilling, keep the speed high and let the drill go through slowly. Put some masking tape over the place you are going to drill. For deep holes lubricate the hole with a lubricating spray like WD-40. For very thin sheet use a stepped drill like the one below. If you don’t the drill will almost certainly catch the sheet and break it.

drill

You can snap acrylic sheet like glass. Score it really well where you want to snap it. Place it on a firm sharp edge with the scored side up, give it a firm strike. This can only be done with thinner sheets.

To bend acrylic sheet. Get a hairdryer or a hot air gun. Place your sheet on a firm heat proof surface with the site of the bend just over the edge. Gently heat the sheet keeping the air gun moving, heat both sides. Do not overheat the sheet because you will burn it. Once it gets really warm put gentle pressure of the part of the sheet not resting on the surface. It will slowly start to droop, encourage it to keep bending. When you get to the angle you want stop applying pressure and heat and hold it there, a damp cloth will help it cool down more quickly. It will be firm again within a few moments. If you have a large industrial oven you can heat it in there and if you are able to place it on a shelf inside it will bend with the aid of gravity. Turn off the oven and allow it to cool naturally.

You can buy a device to bent thin sheet, it consists of a bed with a heated wire running across it. Put the sheet under the wire and turn it on, it will heat to a set temperature, once it is at the right temperature you will be able to slowly encourage the sheet to bend.

Round acrylic rod can be turned and polished on a lathe or milled on a milling machine.

Acrylic can be polished with acrylic polish that comes in a can and comes out as a foam. It can also be done with metal polish or jeweller rouge. To polish a cut edge or a drilled hole start with very fine wet and dry abrasive paper and lots of water, then finish with the metal polish on a cloth. You can do what is called flame polishing, this can be used for an edge. It is not easy and needs some practice to get good at it. With a propane flame very carefully run it up and down the edge until it gets a shine. Do not overheat it.

Do not polish an edge you will want to glue, it will not be so strong.

To glue acrylic you can make your own glue with a solvent and acrylic shavings mixed together to make it thick enough to paint it on with a small brush. I won’t go into the various solvents because they are often toxic. You can buy glue especially for the job.


Simple solution No6.

Need a very mild abrasive?

Try some toothpaste, do not use modern gel toothpastes they won’t work. You have to use an old type of paste, look for an ingredient in it like bicarbonate of soda.


 

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