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How to Use a Multimeter

So, you've got a multimeter but don't know how to use it. While you can surely learn about it, know that it may not be an easy task. Learning how to use a multimeter requires patience and enough knowledge about the device.

Now, how do you really operate this device? Is it solely for professional use or can a non-pro like you handle it well? To answer these questions, you should take time to learn the basics of a multimeter first.

What is a multimeter? What are its parts? How do you use it? Read on and feed your mind with useful information.


Multimeter Defined


A multimeter is an electronic device that tests and measures multiple things. It assumes the roles of various other devices in one unit. Among the things it tests are voltage, current, and resistance.

You can likewise use a multimeter in repairing and troubleshooting tasks. It can detect problems and tell where they come from. Among a multimeter's components are capacitors, diodes, and transistors.

Generally, a multimeter is not really pricey. But if you want the best model with far better features, you will need to spend a quite big amount. Doing so can give you your money's worth should you pick the most feature-filled item.


What are the Parts of a Multimeter?


The device comes in three parts: display, ports, selection knob


Display

This is where a user sees the reading after performing some measurements. Some multimeters come with illuminated displays, which helps a lot in viewing especially in dark or low-light areas or situations.

Normally, the display has four digits. It also has the capacity to show a negative sign.


Ports

Ports are where probes get plugged into. Basically, there are two probes: the black probe and the red probe. The former connects to the ground most of the time

Basically, probes are cables used for connection. They come in the following types:

Banana to Tweezers:  handy especially when you need to test SMD components

Banana to IC Hook: effectively works on legs of ICs and smaller ICs

Banana to Alligator Chipsets: great cables that are beneficial in doing long-term tests; does not require users to hold probes in place as they manipulate a circuit

Banana to Test Probes: cheap and can easily replace broken probes


Selection knob

A selection knob is important especially during the times when a user needs to read different things. Should you need to read voltage, resistance, and milliamps, you would need to move the selection knob to be able to do the desired reading.


How do you Use a Multimeter?


Let us now discuss how a multimeter works. From there, you will gradually learn how to use the device.

First off, a multimeter comes with black and red leads. When doing some testing, you should attach the leads to the portion of the circuit you're trying to test. Afterwards, you will be able to see the results provided by a digital readout.

If you wish to test various things, you will need to move the knob to set the test and perform it. Meanwhile, some multimeters come with an auto-ranging feature. It apparently provides more convenience to users, for it saves them from the hassle of range setting.


Testing Resistance and Voltage

We will focus on these two because they are the common things that a multimeter tests.

For reading resistance:

  1.         Make sure to clip your test leads on your resistor leads.
  2.         Dial the device to a range where you think the resistor suits.
  3.         Make sure to read the given value.
  4.         For measuring voltage:
  5.         Connect the red lead to the battery's positive side.
  6.         Connect the black lead to the battery's negative side.
  7.         Set the dial to your expected voltage range.
  8.         Check the voltage by touching the red lead to one of the battery pack             outputs and the black lead to the other.
  9.         Meanwhile, you should check the voltage between +V bus and a                      ground bus when a circuit does not work. Here is how to do it:
  10.         Remove the ends of a three-inch piece of 22 gauge wire.
  11.         Clip each wire's ends to your test leads.
  12.         Put the end of the wire attached to your red lead to a contact on the              +V bus.
  13.         Put the end of the wire attached to your black lead to a contact on the            ground bus.

Please take note that getting a reading close to zero might be an effect of poorly connected wires from the battery pack. It pays to check it from time and again.


Analogue Vs. Digital


Needless to say, both analogue and digital multimeters serve as great tools for testing and measuring. But these days, digital multimeters are becoming more popular. This is apparently due to the modern times ruled by advanced technology.

Generally speaking, a digital multimeter is more accurate compared to its analogue counterpart. This is the main reason why the demand for analogue multimeters gradually declined.

However, digital multimeters are more costly than analogue multimeters. For this, the former did not fully beat the latter. Not to mention the fact that analogue multimeters can still function well despite being less accurate compared to digital ones.

But as time went by, new features came out in the market. Digital multimeters have become more advanced and capable of offering more advantages to its users.

In the midst of so many advancements, analogue multimeters continued to do what they are supposed to do. They became the perfect choice for people who only need to do some measurements. But for those who want to perform tasks outside measuring, the digital units were the better choice.

In hindsight, it is the user who will define the better option. This is amidst the fact that digital multimeters are generally better in terms of function and features.


Conclusion


By now, it may be safe to assume that you already have an idea on how to use a multimeter. Indeed, everything starts with learning some basic facts and steps. Once you start to learn about the nature of a device, you become ready for further knowledge and real-life applications.

If you have any other questions or worries please contact us, or if you have any comments or improvements please leave a comment at the bottom of the page.

How to Sharpen your Table Saw Blade

The table saw blade is perhaps the most important part of the table: probably its heart and soul. But any serious woodworker knows that taking care of the saw blade is not an easy task. It requires regular maintenance and a great deal of effort and care.

Many woodworkers assume that their table saw blades can’t be sharpened. When the blades get dull, they dispose it and replace it entirely. This is usually very costly compared to how affordable it is to just have the blade sharpened.

If you want to glide through your projects with ease, a well sharpened blade is a must. It will ensure that you have smooth and accurate cuts and there are no rough edges on the cuts. A dull blade will also require you to use more energy to go through the workpieces. To save you from having to get a new blade every time yours goes dull, here is a step by step guide on how to sharpen the blade. Follow closely;


When to Sharpen your Blade


It normally takes a lot of time for some woodworkers to realize their table saw blade requires some sharpening. However, it’s very easy to notice the signs of a dull blade as long as you’re aware of the tell-tale signs to look for on such a blade.

  • Chipped carbide on the blade,
  • Rounded corners or edges on the teeth, and
  • Increased pressure when cutting materials you’ve previously been cutting.

Once you notice any missing or misplaced teeth that are out of the plane, rush it to a professional. Here one can get the old teeth brazed off and get a new set of teeth brazed on. On the other hand, if your saw blade has any of the three remaining signs, then it’s about time to get the blade sharpened.


Cleaning the Blade


At times, when people start to notice more pressure when cutting materials using their saw blades, they usually assume that they are dull. Turns out in some cases, they are not. They are just dirty. Furthermore, the cleaning process usually makes sharpening easier, saves you more time, and less stress.

To clean the blade, it is important to first remove it from the table saw to avoid any inconvenience. Most modern table saws are equipped with release switches. These tend to reduce the hassle when it comes to removing the blade. If you still have the previous models, then you’ll spend a little more time loosening the bolts. If you have a wrench lying around, use it. It will make the process much easier.

 It doesn’t cost you a lot to clean a table saw blade; you just need some soap and a toothbrush. Here’s how to go about it:

Gently apply the soap around the blade, making sure there is adequate of it around the edges and in between the teeth. Be careful to avoid getting cut in the process. Now take the brush and scrub off any metal dirt or chipped carbides that might have remained when using it. Rub the blade in its direction and not against to prevent any injuries.

Once you’re done with the cleaning, dry off using a drier. This is to make sure that dirt won’t form around the blade in the future. Once the cleaning and drying done, one can then check for improved performance in the blade.

Install it back to the table saw and if it still requires more torque to cut wood, then you require to proceed to the next step.


Sharpening the Blade


What you need?

If you want your dull saw blade to be up and running again in the shortest time possible, then you need to arm yourself with a few equipments. The following will help you get your blade in check without wasting much time:

  • A sharpening file – preferably a diamond blade or file. For best results, place it in the form of a grinding wheel. Ensure that it is not worn out and is effective. If possible, get a new one.
  • A sharpie – To mark the starting tooth.
  • Well set up jig – Where you’ll place the dull saw blade
  • Piece of wood – When you can’t afford a jig or have no time to set up one.
  • Gloves – Remember you’re dealing with sharp metals here. So to avoid any accidents in form of cuts, please get yourself a pair.
  • Goggles or a face mask – To avoid pieces of metal shavings from jumping into your eye and causing severe injuries and blindness. Face masks ensure that they don’t get into contact with your face and probably saving you from lung problems.
  • Lubricant – To prevent your saw blade from rusting.

What do you do

It is very difficult to sharpen the saw blade when it is mounted on the table using this method. As mentioned above, use the release switch to remove the blade.

Now carefully adjust the table saw blade on the jig making sure it’s tight and well-fitted. This might take some time to get it into the perfect position. For those who don’t fancy jigs, place it on the piece of scrap wood gently. This prevents the blade from making unnecessary turns or running off when it is being sharpened. Also don’t forget to adjust the diamond blade file fittingly. All this should be done on a safe, smooth and flat surface where you can work smoothly.

Use the sharpie to inscribe a recognizable mark on the blade. Make the mark at the top of the blade’s tooth so that you can easily see it. This helps you to know when you’ve finished making a full circle around the blade. At the same time it saves you from the misery of double sharpening which is a complete waste of time and effort.

Ensure you put on your gloves, face mask, goggles and any other safety equipment. Now steadily lead your blade to the diamond file and slip it in. This should be done slowly. You don’t need to be in a hurry. Working hurriedly increases the probability of one getting injured. Now gently push the blade until it makes slight contact.

With that done, you’re about to start the work of sharpening. Here’s where you need to be very attentive and be as smooth as possible. In this stage, you should start making strong back and forth strokes across the first section of the saw.

Pull the saw blade relentlessly in a back and forth motion about five times while taking note of the progress. Continue rotating the blade the same number of times for each section and you’ll start noticing the difference. In the case of the grinding wheel, put the blade straight across and not at an angle. Take each quarter of the sections by turn and make sure you don’t skip any. Use slight pressure above the table saw blade but don’t push it to avoid any damages.    

Once you’re done with all the teeth, sections and quarters, it’s now time for the last and final step which is lubrication. You only need a small amount of oil because the sharpening is still fresh. Pour some oil all over the table saw blade including all the teeth and edges. Use a newspaper for the best results. Slowly wipe the lubricant on the blade while spreading it to all the parts. Some oil will be wiped off, but this shouldn’t worry you.

It is important to note that the chipped metals can make the floor, (either wooden or concrete), very slippery. Therefore, one should clean the shavings off when the process is done.


Attaching the blade and checking the results

You should attach the blade back to the table saw depending on the removal technique you used. Follow the step closely and mount it to the table until you’re sure it is firm. Don’t forget to check if the teeth are in the direction that they normally rotate.

Some table saw blades usually require nuts to install them on the tables. For these types, tighten the nuts slowly using your hands then tighten them further using the wedge. However, don’t use too much force and over-tighten them.

Once you’re done attaching it, it’s now time to assess the success of the entire work. Place a piece of scrap wood close to the blade and cut it squarely. This is to check whether the saw blade has attained its required sharpness.

 It will most likely cut the wood smoothly if you have followed the process keenly. But if you’re not satisfied and still notice some dullness in the blade, you can repeat the process.


Conclusion


As you have seen above, sharpening your blade is an easy process that any woodworker can easily accomplish. It’s a completely hassle-free and simple process. You don’t need an expert to do it for you neither do you need to find a replacement of your saw blade. This might just be more costly and expensive in the long run.

Keep following this procedure and with time and future re-sharpening, you’ll master the skill that will save you loads of cash and precious time in your woodwork.     

If you have any other questions or worries please contact us, or if you have any comments or improvements please leave a comment at the bottom of the page.

What Gas do Plasma Cutters Use?

Plasma cutting is one of the fastest cutting processes on aluminum, carbon steel, and stainless steel. The process uses hot electrodes to cut through electrically conductive materials. Invented back in 1955 by ESAB, this method can be used for cutting on materials of up to 6 inches thick.

To achieve the best quality, productivity, parts life, and reduced cost of operation, different gas types are used on different types of material. Each gas has its own advantages and disadvantages. Simply put, selecting the right gas depends on the metal being cut, the equipment used, and the desired performance.

Here, we have provided a brief overview of each gas and the quality of the cut based on the three conductive materials mentioned above (aluminum, carbon steel, and stainless steel.)

Plasma Gases/ Materials

Aluminum

Carbon Steel

Stainless Steel

Air

Good cut quality and speed. Very cost effective

Cost effective and provides a precise cut with adequate speed

Good cut quality. Moderate cutting speed

Oxygen (O2)

Not recommended

Excellent cut quality and speed. Little to no dross

Not recommended

Nitrogen

Excellent parts life and cut quality. Highly recommended

Great parts life, fair cut quality

Good cut quality. Great parts life

Hydrogen

Great cut quality. Excellent parts life

Excellent parts life. Good cut quality, some dross

Excellent cut quality and parts life

Argon

Excellent cut quality. Works great on thick materials

Not recommended

Excellent cut quality. Works great on thick materials

Air is one of the most adaptable forms of gas available. Introduced in the early 1960s for improved slice quality, air gas produces good cut quality while offering good speed for cutting aluminum, stainless steel, and carbon steel. Since you do not necessarily have to purchase this form of gas, the cost of operation is drastically lowered. However, shop air is a great option as it is cleaned beforehand. This cleaning process eliminates any contaminants such as moisture, oil mist, and other particulates.


    Air


Air is the widely accepted and used gas for the purpose of slicing sheets of unalloyed, low alloyed, and high alloyed stainless steel. When using air plasma, air shield gas offers the best option since it contains a mixture of approximately 80 percent nitrogen and 20 percent oxygen. The oxygen found in the air provides additional energy which increases the speed by around 25 percent over cutting with nitrogen.

A major drawback derived from using air gas is that the cut surface on stainless steel and aluminum materials might get heavily oxidized, which is unacceptable for most applications that do not require secondary operations such as grinding.


    Oxygen


This gas is best used to obtain fast cutting speeds at lower power levels. Oxygen is ideal for cutting structural low-carbon and low alloy steel. It is capable of processing a wide range of conductive material thicknesses.

When used to cut carbon steel, oxygen increases the cut speed and helps remove all molten materials to create a clean and smooth edge. To cut through thicker steel, it’s recommended to mix some nitrogen in the shielding – this can either be an Oxygen-Nitrogen mixture or Air-Nitrogen mixture.

The major disadvantage of oxygen is the decreased parts of life and the cost of purchase. Note that plasma cutting stainless plate or aluminum plate with oxygen gas is not recommended.


    Nitrogen


Nitrogen is a great option for anyone planning to cut tons of aluminum and stainless steel. This plasma gas offers excellent parts life and great quality on the cut.

Nitrogen, however, is not as effective when used on thick materials. For best results, it’s best to substitute it with Argon-Hydrogen. Nitrogen can be applied together with air or h2o as an alternative gas to become shield fuel.

This application helps cut smooth edges, particularly on stainless steel and aluminum. If you are planning to use h2o, as the alternative fuel, using it within a water platform will make the action more effective.


    Hydrogen


Hydrogen has a high concentration level of thermal conductivity which allows for higher power denseness. Hydrogen plasma gas is environmentally friendly as it reduces the emission of CO2. The gas produces high quality of cut surface and helps reduce the labour required for finishing after cutting materials. This gas contributes to high productivity thanks to its high-speed cutting which also results in a reduction of running cost.

When Hydrogen gas is used, the base metal receives lower heat input. The process reduces thermal distortion significantly thereby producing high precision cuts. In addition, the cut surface is smooth and the corners are sharp, bringing about an excellent cut quality.

One of the main advantages of using hydrogen gas is the easy separation of dross (slag). Similar to other gases, Hydrogen cutting does generate slag. However, the slag can be easily removed which results in fewer man-hours required to finish off the cut-out products.

Hydrogen plasma gas has a higher cutting speed of 10 to 30 percent when compared to other gas cutting. In addition, since the cutting time is reduced due to the exceptional heat concentration, the overall productivity is improved.


    Hydrogen


For thick aluminum and stainless greater than ½,’’ argon is a suitable choice of gas to use. Keep in mind that argon is not recommended for use with carbon steel products. Argon does not react with materials during cutting and is therefore classified as an inert gas.

It cannot be used as a single cutting gas because it has a low thermal capacity. Plasma cutting is only used on the above-mentioned materials, primarily; carbon steel, aluminum, and stainless steel. However, there are tons of other alloys and metals that are conductive including brass, Inconel, copper, cast iron, titanium, etc. The major problem with using this method of cutting is that the melting degrees of some of these materials make it hard to receive a precise cut with clean cut edges.


    Plasma Gas


Also referred to as PG, it refers to all gas mixtures which are used to generate the plasma beam and help cut through conductive materials. There are five main plasma gases namely:

∙ Air

∙ Nitrogen

∙ Hydrogen

∙ Oxygen

∙ Argon

Plasma gases can further be classified under three main phases including:

Ignition gas (ZG) – This is the gas used to light up the arc and help start the metal cutting process.

Cutting gas (SG) – Cutting gas determines the cutting speed and the cutting results. First, the energy derived from the arc helps soften and melt the metal. The melted metal is then pushed out of the cutting gas. Keep in mind that the cutting gases used differ based on the thickness and material type.

Marking gas (MG) – This is the gas used for plasma marking.


Swirl gas

Swirl gas covers the plasma beam and helps increase the cutting quality. This method increases cooling and assists cutting in several different ways. It also helps protect the product during underwater cutting and piercing.

Sealing gas (SPG)

Sealing gas is similar to swirl gas but it has reduced volume flow rate, especially when used for underwater cutting. The gas prevents any water from entering the torch head when being operated underwater.


Control gas

Also referred to KG, it controls the protection cap. Control gas ensures that the torch is properly installed at all times. This is important because an improperly installed torch might lead to zero performance.

Identification gas (IG)

 IG gas is used to locate different torch heads.


    What does Gas Swirling Do?


As mentioned above, swirling helps increase cooling and enable a user to cut their materials in several different ways. This method helps improve cut quality and provide exceptional parts life. The heat from the beam is then evenly distributed along the side of the cut.


     How do Plasma Cutters Work?


A plasma cutter uses electromagnetic gases to transfer energy from a power supply to a conductive material for a clean and fast cutting process. A plasma system is inclusive of these components:

Power supply – It converts an AC line voltage into a constant DC voltage which can range from 200 up to 400 DV. The DC voltage is then used to generate enough energy to cut through a certain material.

Arc starting console – The circuit found inside an ASC produces AC voltage of up to 5,000 VAC at approximately 2 MHz. This voltage ignites the plasma torch to create the plasma arc.

Plasma torch – There are three major components (also referred to as consumables), inside a plasma torch body. These components will require replacement overtime as they tend to get consumed during a plasma cutting process. They are:

∙ Electrodes

∙ Gas baffle (swirl baffle)

∙ Nozzle

A plasma torch might come inclusive of a shielding cap to further enhance the cutting quality. The two common methods of cutting include:


Arc cutting

This procedure works by sending an electric arc through a gas that is then passed through a small constricted opening. This small opening helps elevate the temperatures of the gas from solid to liquid to gas, and finally to plasma (also known as the 4th state of matter).

The small nozzle allows the gas to squeeze through at a high speed. The high speed gas emitted is directed around the perimeter of the cutting area to shield the cut and provide a precise cut.

Modern plasma cutters come inclusive of a pilot arc that is wedged between the cutter’s snout and the electrode. This arc is used to iodize the gas and generate the plasma before it’s transferred to the metal.


Plasma Torch

Another method that is being used in many of today’s plasma cutters is a plasma torch. This method uses a copper snout to compress the iodized gas and focus it to a small section of the conductive material being cut. It works in a similar way to how one uses a magnifying glass and the sun’s rays to create a beam of heat.

Note: Pilot arc and Plasma torch methods are not compatible with CNC (automated) cutting.


     Important Variations Involved in Plasma           Cutters


For maximum quality and production of your materials, you need to ensure that all components involved in the process maintain a healthy balance.


Gas

The cleanness of the gas is of great importance if you want to achieve excellent parts life and great cut quality. The requirements for oxygen are 99.5 percent whereas the minimum clean levels for nitrogen are at 99.995 percent.

The following could happen if the cleanness levels are lower than the above stated:

  • Extremely short parts life
  • Variation in cut quality
  • Inability to cut through materials no matter how thin they are
  • You might experience some debris in the nozzle

Aside from gas purity, the gas pressure plays a major role in plasma cutting. Each nozzle has a set current based on the maximum amount of pressure to instill. Increasing gas pressure might result in a notable decrease in the overall performance and electrode’s life whereas decreasing the pressure will undoubtedly result in a double arc failure.

Other variations to keep an eye on include:


Water

Use filtered water as some minerals can affect nozzle life and the plasma cutting process. Also, excess water pressure might cause the arc to produce poor results


Kerf

This refers to the width parallel to the torch and cut axis.


Arc voltage

This variation is dependent on the standoff, cutting speed, current (Amps), nozzle size, gas and water flow rate.


     Conclusion


Plasma cutting has enabled us to perform precise and quality cuts on many types of conductive metals. Different gases can be used to perform plasma cutting. All you need to do is determine the thickness and material type beforehand. This type of cutting up steel, aluminum, carbon steel, and other alloys is easy to master and faster than other types of cutting such as oxyfuel cutting.

If you have any other questions or worries please contact us, or if you have any comments or improvements please leave a comment at the bottom of the page.