By: Steve Aucremann
Piezo handpieces are not all created equal. In fact, they fall into two distinct categories: the EMS type and the Satelec type. The important difference is the thread pitch which is finer on the EMS and courser on the Satelec. The only difference that you can see is the Satelec style has 2 flats where the tip wrench goes, and the EMS has 4 flats.
If you (or your customer) purchase the wrong tips by mistake, they will only go on about half way (see picture to right). If you use the tip wrench you can force it on, and it will go but stripping the threads is the outcome. Soon you will have the results you see in the bottom picture. The threads stripped or broken off entirely (picture bottom right).
The replacement tips cost between $65 and $100, and the handpieces cost between $250 and $500. Say an office has one EMS scaler and 5 tips that they use on a regular basis. Now, one tip breaks, so the office manager orders a new one from the picture in the catalog and gets the Satelec by mistake. The Dr. starts to use it, and it won't go on, so he uses the wrench and forces it to fit. He has now distorted the threads. The next time he puts on the right tip on but it is tight too. So he forces it on, and it works okay. Over time, he will destroy the handpiece and all the tips costing around $1000.
So, What to do?
Know what you have and purchase only the proper replacement tips.
If you are using a new tip (or any tip) ,and it will not thread all the way down easily with just your fingers, STOP and do not force it.
If a Dr. sends you a scaler handpiece, and the threads are stripped or broken off, they need a new handpiece.
If you are selling tips or handpieces to your customer, make sure you check all these things. You don't want to be the cause of the problem.
If you are going to send us a handpiece for repair, please be aware that very little can be done to save them. I can fix water leaks, clean electrical contacts, and replace broken plastic parts, but not much more.
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By: Steve Aucremann
In our article last March on "Electric Motors in Dentistry" we gave you some background on how electric motors work and how to diagnose the problems they may have. In this article we are going to look at ways to improve the life and reduce the cost of repairs on electric motors and their attachments. Keep in mind that heat is the enemy and is constantly being generated, first by the electric motor, then by the gears and bearings in the contrangle and finally by the gears and bearings in the head shell. The three sources of cooling in an electric system are the water spray, the chip air or coolant air and the drive air. The drive air flows up through the motor, then the contra angle then out the back of the head shell, providing cooling along the way. The coolant air and water travel out through holes in the front of the head shell cooling the head shell and the burr as it is cutting. The goal is to maximize this cooling effect and to help the customer understand how these things work. The examples we are using will be the Adec Dental Cart and the Kavo Electrotorque Plus electric handpiece system but the principles apply to any unit out there today.
When an electric handpiece system is properly installed the system pressures should be set to the required levels. However things can change over time and not every installer pays attention to detail. As a result we see a number of handpieces and attachments which are damaged because of inadequate pressure. The drive air in the electric handpiece motor system serves 2 purposes. First, it controls the speed of the motor through a pressure sensor on the circuit board inside the controller. This is a passive function requiring only the pressure not the flow of air. The second purpose is cooling the motor and attachment while it is running. This completely dependent on an adequate flow of air, inadequate air flow can lead to motor and/or attachment failure.
This “Air Requirement” (Figure 1) list was taken from the Kavo Electrotorque installation instructions. For our purposes a Bar is roughly equal to a kg/cm2 ( that is the outer numbers on the gauge showed below) and equal to 14.5 PSI so 4.5 Bars is 65 PSI. Understanding the nomenclature is also important, what we call coolant water, Kavo calls spray water some call it handpiece water and what we call coolant air, Kavo calls spray air, some call it chip air.
First you should check the pressure coming into the dental unit, is between 70 and 80 PSI and that it will not drop more than a few pounds when you run a handpiece. If the pressure is too low adjust with the main air regulator (Figure 2), if it drops down when you run a handpiece, check the air filters (their may be more than one) and any valves that may not be open all the way, and look for any pinched or twisted tubing, restricting the air flow. If the unit has adiquate air supply then continue by checking the handpiece pressure to the electric handpiece control. Air driven handpieces require between 30 and 45 PSI and more than that will shorten
the life of the handpiece (note there are exceptions to this). The electric motor needs 65 PSI or more at the highest point in order to provide the cooling required. Some manufacturers have flow meters (Figure 3) available to measure the actual flow of air through the motor and out to the attachment. This is of corse the most reliable way to determin the air flow but they are expensive and its hard to justify the cost.
At the factory default settings, most electrics will come on at 30 psi and reach maximum RPM at 65 psi raising the handpiece pressure above 65 psi is a good way to increase cooling, but most units max out at around 65 PSI. Increasing the pressure above 65 PSI will not effect the motor rpm because once it reaches maximum it can not go any faster. This ratio of presure to RPM can be altered, in the Kavo system and maybe others, I mention this only because we have had systems come in with the complaint that “it wont go fast enough” and we find that it is not reaching full RPM untill 70-80 psi and most likely the doctors unit cannot reach that pressure. Our solution is to restore the factory settings which can simply be done by pressing the Forward/Reverse and the Up and Down arrows at the same time and hold them for about a second or 2.
Adjusting the handpiece pressure is also a simple task. Here is an example.
In this case we have an Adec cart which has very simple controls on the right hand side. Determine which handpiece the electric system is connected to and insert the Adec adjusting tool (or just a 3/32 in allen wrench) into the adjusting hole that corrisponds to that handpiece (Figure 4). Turn it clockwise to decrease the presure or CCW to raise it, with the foot control pressed as far as it can go.
Adjusting the coolant water and air flow, is not as scientific, but the rule of thumb is to keep as much water as you can without drowning the patient, and as much air as you can get without interrupting the water flow. With an attachment and burr on the motor, start by turning the coolant air clockwise till it goes off (if there is a toggle switch to control the coolant air, use that). Then with the coolant water switched on, (switch may be on the unit or on the foot control or both) first adjust the valve on the handpiece connector (if there is one) to full open then adjust the coolant water on the dental unit water until there is more than enough water (the Doctor will have to fine tune this to suit his needs).
Adjusting the coolant air can be more complicated. First turn on the coolant air and increase until it begins to reduce the water flow then back off to a strong spray, the problem is that many units, like this Adec, have one coolant air control shared by all the handpieces, so you have to compromise and find the setting that works for all the handpieces. With the water and air set at the highest usable level, the Doctor can fine tune it to suit his needs. Always try to help him to understand that he wants as much coolant water and air as he can stand because it will make his handpiece last longer, and save him money. Now that we have maximized the cooling potential lets cover a few other areas quickly.
It is hard to impress strongly enough that when an attachment or a motor (or any mechanical device) begins to make noise or act strangely, you should STOP using it and get it fixed! Continuing to use a handpiece after a bearing or a gear begins to fail only multiplies the cost of repair. It is also important to inspect for physical damage such as dents in the head shell which will often cause rapid failure as well as enough heat to injure a patient. Here is an excerpt on the subject from the Kavo manual:
A proper procedure for cleaning, lubricating and autoclaving, which is followed and checked on a routinely is essential to maintaining dental handpieces. Here are a few guidelines:
- After a procedure remove the attachment from the motor and rinse it in cold tap water and scrub the outside of the attachment with a toothbrush, being careful not to run water down the back end of the attachment where the motor goes. Allow it to drain head down to remove impurities (this is especially important when corrosive solution like prophy paste, saline solution or sodium hypochlorite, have been used in the procedure). Leaving the attachment on the motor in a handpiece hanger allows contaminants to run down into the bearings and gears.
- Follow the lubrication and autoclaving procedures recommend by the manufacturer and if large amounts of debris come out of the handpiece, repeat the procedure. If a machine such as the Quatrocare or the Assistina is used always check to make sure it is working properly. We see many handpieces that are lubricated on an Assistina, that have dry bearings because the Assistina is not working properly (see our article about the Assistina at http://www.floridadentalrepair.com/blog/assistina.php)
- Autoclave the handpiece per manufacturer specifications being careful not to exceed the maximum temperature, autoclave maintenance and monitoring are essential. Also allow for proper drying time and store the handpiece in an upright position until using it again to allow any moisture to drain out. Finally do not re-lubricate after autoclaving. We also recommend running the handpiece for a few seconds before entering the oral cavity to dispel any oil that may have been left behind.
This is certainly not everything there is to say about electric handpiece maintenance but it is a start. Please call me or post any comments or questions or suggestions you may have.
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By: Steve Aucremann
Electric Motors in Dentistry
In case you missed it, electric motors are rapidly replacing air driven handpieces in the dental industry. Although this has long been the standard in Europe we in the US have been slow to change. The primary advantage of the electric motor over air driven is the torque and as a bonus it is much quieter, easing the tension caused by whining air turbines. The down side is of course is the initial cost and the expense of repair.
In the world of electric motor handpieces there are 2 primary technologies, the brush motor (old technology, on the way out) and the Brushless motor most new systems are built with brushless motors they are more reliable and efficient as well as giving more accurate control over speed and torque.
The brush motors operate off of DC current which is applied to carbon brushes that contact a circular commutator which has between 6 and 24 segments each opposing pair of contacts attaches to either end of a coil of wire on the rotor or armature. When the coil is energized it creates a magnetic field which pushes against the opposing force of the stator (usually a fixed magnet or magnets attached to the inside of the case of the motor) which causes the rotor to rotate to the next pair of contacts which energizes another coil and round and round it goes.
You will find brush motors in Lab handpieces, Operatory handpieces, even Implant handpieces. The primary problems you will find are:
- Bad bearings (from contamination or age).
- Worn brushes and/or commutator.
- Open winding in armature.
- Broken wire in the handpiece cord requiring re-termination or replacement.
Like the brush motor the brushless motor uses a coil of wire which is energized to create a magnetic field that pushes against an opposing field in a permanent magnet. However in the brushless motor the magnet is on the rotor and the coil is fixed. The pulses required to make the rotor go round and round are generated by a Microprocessor instead of brushes contacting a commutator. This is why we say that the brushless motor runs on a commutated signal not a DC voltage. It is also why a brushless motor needs at least 4 wires (conductors) and the brush motor only 2.
As a result of the lack of brushes the brushless motor;
- Is quieter and has less overall vibration.
- Is cooler (most brush motors need a fan)
- Can be designed to run faster and longer with a higher duty cycle (more time on less time off)
- They require less maintenance.
The down sides to the brushless motor are;
- They must have a specific controller to be properly tested and sometimes the controller is the problem.
- The magnet on the rotor can crack or break up (often if the handpiece is dropped)
- Because these are often surgical handpieces they are autoclaved which degrades the windings and bearings over time.
- Broken wires are often a problem probably because they require more conductors and are therefore smaller and more fragile.
- The added layers of technology i.e. the microprocessor, the use of hall effect sensors and torque control makes problems harder to diagnose.
So what does it all mean
Really it just means we have to work together on these to get the best result for the customer. We have tried to distill this down to a few rules of thumb;
When you pick up an electric motor get as much information as you can, here are a few questions to ask.
- Did the motor run or not?
- Was it making noise or vibrating?
- Do other motors work on that controller?
- Did the motor go on and off if you twist the wire?
- Is the motor getting hot?
- Is the motor going slow with a jerking motion?
Try and determine if it is a brush motor (the motor runs on 2 wires is the easy way) and if the control works with other motors then just send the motor. If they do not have an extra motor to run with the control then you may as well send in the control with the motor.
If you can put a straight nosecone with a burr in it and spin the motor you can learn a lot.
- If it turns freely and the motor will not run when attached to the control, then putting bearings in it will not help.
- If it won’t turn or feels like a box of rocks when you turn it, the rotor has most likely exploded and must be replaced,
- If the motor runs but is loud, and the bearings feel rough when you turn it by hand, it can likely be fixed with bearings
- If the motor runs but jerks or stops, or causes an error when you twist the cord then it may only need a cord re-termination.
The following is a list of the systems we have in house to test handpieces with:
- KAVO Electrotorque – will test KAVO 198 and 200 motors (brush motor)
- KAVO Electrotorque plus – will test KAVO 700 and 701 brushless motors
- KAVO Comfort drive system – will test 200XDR motor
- NSK – will test the NSK NL400 brushless motor
- Sirona Classic – will test the Sirona Classic brush motor
- Sirona ISO will test Sirona E-type motor and the Classic brushless motor
- ADEC W&H will test the EA40-LT EA51-LT and EA52-LED (but not feedback circuit)
- Dentsply Aseptico will test most Dentsply or Aceptico brushless motors
- W&H 3i implant 4 pin will test most W&H 4 pin brushless motors
- W&H Implant Med 5 pin will test most W&H 5 pin brushless motors
- Stryker Command II – Stryker Command II brushless motors only
- By Dental Hi tech Implant will test By Dental and Hi tech Implant brushless motor
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By: Steve Aucremann
Hall Surgairtome E, Hall micropower, Stryker impaction drill, Core impaction drill,
Commonly found in the Oral Surgery practice, this type of handpiece has a great deal of torque to cut through tooth and bone easily. They are typically powered by a brushless motor and have hall sensors which feedback information to the controller. Some systems have a hand control (shown) and others have a foot control. In a perfect world, we would always get the controller with the handpiece for the purpose of complete testing. Unfortunately the controller is often needed to stay in the office to run other handpieces so we need to get the following information
- Did the motor run? – if it did not then the controller and the cord must be tested with another handpiece to be sure the problem is not with them.
- Was it loud? – noise indicates a bearing problem which is taken care of in a standard overhaul
- Did it over heat?
- Did it hold the burr well?
Core vent, Aseptico, ATR 3000, Anthogyre, 3I implant system, W&H implant, Dentsply implant, etc, etc
A system like this is used for dental implants or endodontic procedures. Typically they have a brushless motor that runs at 40,000 rpm (some older systems have a brush motor). Of the brushless systems some have hall sensors and some do not. If the motor cord plug has 2 or 3 pins it is probably a brush motor. If the motor cord plug has 4 to 6 pins it is probably a brushless motor without hall sensors. If the motor cord plug has 7 or more pins it is probably a brushless motor with hall sensors. By now you’re asking “why do I need to know this?” Well here is why: We can easily test a brush motor so if you are sure the controller is ok we only need the motor. We can also test the brushless motor without hall sensors but it is better, if the ‘Dr can do without it, to send the controller with the motor. The brushless motors with hall sensors almost always need the controller for proper testing. Here are a few of the issues we look for in these systems:
- Broken wires in the cord, this is caused by autoclaving and general abuse. We can re-terminate most of them.
- Rough bearings can normally be replaced but some of them use a modular motor which cannot be repaired it must be replaced.
- In the brushless motors we often find that the rotor has exploded and this requires a OEM replacement which can be expensive. You can usually tell if this has happened by putting on a straight nosecone with a burr and turn the motor, if it won’t turn or feels like a box of rocks, it probably exploded.
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By: Phil Leinbach
What the heck is a 200 XDR?
The 200 XDR is Kavo’s latest entry into the electric high speed market. This unique handpiece is the same size as the 25LPA or any of the ISO highspeed electrics with one big difference: the motor is built into the handpiece! That’s right, there is a tiny brushless motor built right into the rear of the contra angle. This eliminates the need to have a huge, heavy motor hanging off the rear of the handpiece. This reduces the weight of the handpiece from 13 grams to 5 grams. The control unit is much simpler too, no front panel or buttons just plug-in the power supply, connect the dental unit and the handpiece and you’re ready to roll.
This is a great simplification over the 25LPA since the 25LPA has eight bearings plus two in the motor for a total of 10 bearings and the 200XDR only has six. They do this by eliminating the intermediate assembly and running the motor at 188,000 RPMs.
These handpieces are just now getting out of factory warranty and I’ve seen about 10 so far. I’ve been surprised by their performance, that little motor makes a lot of usable torque, in fact, the XDR seems to be equal to or better than the 25LPA without the big clunky motor!
Here is what Kavo has to say about it:
The KaVo COMFORTdrive 200 XDR, operates at only 55 dB, making it the quietest high-speed handpiece on the market today, and features KaVo’s industry-leading chuck strength. The chuck strength delivers exceptional bur concentricity for precise cutting and safety. The bur concentricity and chuck strength further establish KaVo COMFORTdrive 200 XDR as the Dental handpiece for all your high-speed handpiece needs.
KaVo COMFORTdrive’s unique patented design weighs approximately 40% less and is 15% shorter than market-leading high-speed electric handpiece options. The integrated motor reduces the distal length after the pivot point in the doctor’s hand allowing for an unprecedented degree of control.
The KaVo COMFORTdrive system consists of the COMFORTdrive 200 XDR handpiece, the COMFORTtronic control box and the COMFORTbase coupling.
The COMFORTtronic control module features an auto-calibration “ Plug-n-Prep” which allows for air-like “feathering” between 30,000 - 200,000 rpm with the foot pedal. It works off the current air source and no adjustment is required of any other equipment in the office.
KaVo COMFORTdrive 200 XDR works the way you are accustomed to working with air-driven instruments. Therefore, doctors using air-driven handpieces can seamlessly transition to KaVo COMFORTdrive 200 XDR with no learning curve.
Sleek and compact, the COMFORTtronic module neatly incorporates into any operatory, offering an aesthetic, clean look in your dental practice. Simply dedicate the high-speed slot in your dental unit to COMFORTdrive and maintain your existing low-speed option. COMFORTdrive will be available as an integrated option into the Pelton & Crane Spirit 3000 series of delivery units soon.
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By: Steve Aucremann
It has also come to my attention that some of our dealers don't know we do this. So I need to make two important announcements:
We sell rebuilt exchange Copeland 1hp compressor heads!
We buy your old Copeland 1hp heads!
When a Doctor calls and says "I DON'T HAVE ANY AIR" it’s a bad thing. The air compressor is the heart if the dental office without it, everything stops. The best thing is to be proactive and catch a problem before it becomes a crisis. You should make yourself a check list:
- Check the oil level (if it has oil) it should be at least the middle of the sight glass and not over the top. Sometimes the sight glass is stained so always jiggle or shake the head to see the oil moving before you decide if it is OK or needs more oil. Most manufacturers recommend checking the oil every week I would say never less than every month.
- Listen for knocking noises or leaking sounds, while the compressor is on and the office is working is the best but you may have to do this after hours. You want to pay attention to the run time because you want the compressor to be off longer than it is on while the office is working. If it runs all the time or cycles very quickly check the compressor system and the office for leaks. If a problem seems to exist and it is a twin or triple head run each head separately to see if only one head needs work.
- Drain the tank if it has any water in it you should check the air-drier to make sure it is working properly.
- If you find that a head only hums then clicks off, hum click, hum click, then you should check a few things. First (after making sure the power is off) check the oil again, without oil the crank shaft could have seized. The best way to check this is to drain the oil and see if it has any metal in it, (if it does that is probably ground up piston rod) If you still are not sure then take the rear cover off (that's the big round end with 14 half inch bolts) and see if the rotor turns freely. If all that seems OK then check the resistance of the winding by taking off the top electrical cover and check the resistance between R and S which should be between 5 and 8 ohms. If it is much over or under that the motor might be bad.
- If you determine that a head should be good, then check the components in the start box which should have a potential relay, a start capacitor and a run capacitor the easy way to test these is by replacing them. Often you can find these locally from an appliance or refrigeration supply.
- A few final notes, these things are heavy (85 -100Lb), and they are often dirty and oily, be prepared. If you need to replace one get the voltage from the name plate typically 115, 230, or 208-230 and make sure it is 1Hp.
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By: Steve Aucremann
Sonix 4 Corporation uses stainless steel in manufacturing the industry's leading ultrasonic cleaning systems. As such it is important for our customers to have some level of education in regards to the makeup of stainless steel which will ultimately say something about the integrity of the metal when in the working environment.
Over time some users may have noticed the creation of holes within the stainless steel tank. These holes, or pits, can cause serious problems once moisture is allowed to leak into the electronic components of the ultrasonic unit. Once a pit is created, and the unit is run for any period of time, we can expect the hole to exponentially increase in size. This is due to the powerful cavitations that occur when a Sonix 4 ultrasonic unit is in operation. So the question that becomes important is, "How can I prevent pits from being created in the first place?"
The answer comes from the knowledge of the chemical makeup of stainless steel, and the dangers that the working environment can introduce into the ultrasonic tank. Stainless steel differs from carbon steel in the fact that it contains more Chromium. Carbon steel will corrode when it comes in contact with the air and moisture due to the active film of iron oxide (Fe(OH)3), or rust, on the surface. Stainless steel with Chromium is resistant to, but not free of this reaction. There is an active film of Chromium oxide (Cr(OH)3) on the surface of stainless steel, and this active film causes concern when in the working environment. In the instruction manual that accompanies the Sonix 4 product there is a list of solutions known to be harmful to the stainless steel tank due to their low pH, or acidic content. The easiest way to think about the reaction that happens to the surface of the stainless steel is with the net ionic equation of any acid base H20).óreaction (H+ + OH- From this equation we can see that the addition of any acid onto the basic surface (due to active film of chromium oxide) of stainless steel will indeed react. The product of the reaction can be visually seen over a period of time in the form of holes, or pits, in the tank.
There is yet another way that acid can be introduced into the tank other than direct addition of acidic solution. They way to think about this is cavities in your teeth. We spend lots of money and time cleaning our teeth to keep them free of bacteria because bacteria produce acids which will react with tooth enamel (Ca5(PO4)3(OH)). This is the basis for the Sonix 4 recommendation that regular cleaning maintenance is necessary to prolong the life of the ultrasonic tank. If the unit is used to sterilize, but is not cleaned after use then there are microscopic bacteria hard at work producing acid solution that will react with the stainless steel creating microbial erosion of the tank. Over time this microscopic process becomes more and more visible as the holes get larger. Furthermore, as stated earlier, once the smallest amount of erosion has occurred the ultrasonic cavitations will be cannibalistic in that they will aid in the rapid erosion of the ultrasonic tank.
So, in summary, "How can I prevent pits from being created in my ultrasonic tank?" Prevention primarily comes from the regular cleaning maintenance of the ultrasonic tank after use. The list of solutions not to be used in Sonix 4 ultrasonic units (Instruction Manual) should also be consulted.
Used by permission from Sonix IV
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