The photo below shows the popular carvers found on the market today. Let's check them out with our test equipment and see how they compare.
From left to right: SCM Original Power Carver (entry level), SCM Power Carver (entry level), Shofu Lab Air-Z (rebranded SCM Power Carver 400xs), Powercrafter, NSK Presto, Unbridled Vortex XJ7, Turbo Carver.
Six High Speed Turbine Carvers, The Burs
Even though seven carver are shown, only six choices are available when it come to selecting a high speed carver. So how do you decide which one to purchase? Start with the bur as the first criteria. The bur is the part that does the cutting and they all have the same diameter shaft of 1/16" or 1.6mm and they fits all the carvers. The bur head comes in many different shapes and sized. Only high quality burs should be used for carving. Most burs are rated for 360,000 - 400,000 RPM. The speed of the tool must be run lower than the bur's maximum RPM rating or you risk injury. If you run the tool faster than the bur's rated speed, the bur will disintegrate.
Power or RPM? What is the truth?
The second criteria is the power output, not how fast the bur is rotating. The reality is the power is increased as the RPM is reduced until the "Sweet Spot" is reached where maximum power is being delivered to the bur head for cutting.
Air Pressure & Turbine Bearings
Is there an ideal air pressure to run a carver? Carvers run at lower air pressure lack enough power to cut. At higher pressures, the RPM will be great, but the life of the turbine is compromised and short lived. Permanently lubricated bearings are designed last 1,000 to 2,000 hours with a maximum air pressure of 36-38 PSI. Higher pressures of 45 PSI or more are reserved for wet bearings, meaning they require a drop of oil every 20 minutes to an hour of use. Ideally, a carver requiring an air pressure of 34-38 PSI is a good range for carving. An interesting side effect when carving is the ability of the bearings to handle lateral loading. This is the ability for the bearings to handle the sideways cutting when carving. Since carving is not the same as drilling, most of the force the bearings see is sideways and not downwards. Small diameter bearings have a high failure rate, while large diameter bearings are able to take the load much better. Carvers are designed using two bearings holding something called a "spindle". The spindle holds the bur in place as you carve. If the bearings on the spindle are close to each other, they cannot handle the lateral force, the sideways carving. Bearings spaced further apart on the spindle, not spindle length, are much better for obtaining a longer bearing life.
Test Equipment used to evaluate the carvers
Here is the equipment we used to measure each carver:
Torque and Power, Stall Torque Method, Diameter 1.62 mm, Pressure 0.25 MPa (36 PSI)
Noise/Loudness, Digital Sound Level Meter, 30-130dBA, 32-8.5KHz, 18 inches
Full disclosure, we the SculptingStudio have sold Turbo Carvers, Powercrafters and Power Carvers for many years, but elected to discontinue their product lines. We discontinued selling the Turbo Carver brand due to poor reliability. The Powercrafter brand went out of business. We discontinued the SCM Power Carver line due to turbine failures and lack of quality.
Weights and Measures
The carvers were put on graph paper with ¼ inch scale squares along with a rule for accurate length measurements. Widths of the carvers are easily estimated by the scale squares. Weights were measured using an Acculab V-3000 laboratory scale with a readability of 1 gram. A video below the photo shows the weigh in.
From top to bottom: SCM Original Power Carver (entry level), SCM Power Carver (entry level), Shofu Lab Air-Z (rebranded SCM Power Carver 400xs), Powercrafter, NSK Presto, Unbridled Vortex XJ7, Turbo Carver.
Order of weigh in: SCM Original Power Carver (entry level), SCM Power Carver (entry level), Shofu Lab Air-Z (rebranded SCM Power Carver 400xs), Powercrafter, NSK Presto, Unbridled Vortex XJ7, Turbo Carver.
For this test, we use dB(A) Digital Sound Level Meter, 30-130dBA, 32-8.5KHz at a distance of 18 inches. This is about the distance your ears will be from the carver while carving. The meter was placed next to the artist's ear and the tool was run for a few seconds to get a stable reading. The measurement scaled was A-weighted. A-weighting is the most commonly used of a family of curves defined in the International standard IEC 61672:2003 and various national standards relating to the measurement of sound pressure level. A-weighting is applied to instrument-measured sound levels in an effort to account for the relative loudness perceived by the human ear, as the ear is less sensitive to low audio frequencies. It is employed by arithmetically adding a table of values, listed by octave or third-octave bands, to the measured sound pressure levels in dB.
The Decibel Loudness Comparison Chart provides some interesting numbers to help you understand the volume levels across various sources and the affect on hearing.
Whisper Quiet Library at 6'
Normal Conversation at 3'
Telephone Dial Tone
OSHS Max Safe Level
Hearing Loss Begins
Jackhammer at 50'
Permanent Hearing Loss
Jet Engine at 100'
Each carver was tested for sound pressure in dB(A) (loudness) at the manufacturer's maximum air pressure. There is a digital air pressure gauge in the upper left of the video showing the air pressure entering the tool. After the dB(A) measurement is captured, a few seconds of carving was done to see if the loudness changed.
Mass Air Flow Measurements
The six popular high speeds carvers have their air flow measured at the manufacturer's specified maximum air pressure. The more air flow (larger number on the mass flow meter), the higher the power the carver is capable of producing.Carvers measured: SCM Power Carver (entry level), Shofu Lab Air-Z (rebranded SCM Power Carver 400xs), Powercrafter, NSK Presto, Unbridled Vortex XJ7, Turbo Carver.
Equipment used for measurements were "Accumulator Air Tank, 3 Gallon", "Pressure Regulator, SMC ITV2030, 0.005-0.5 MPa (0-72.5 PSI), 0-5 Volts", "Volumetric Flow Rate, Mass Flow Meter, Sierra Instruments, 0-5 Volts, 0-70 SLM".
This section is being updated. Test results will be published along with videos of the actual testing procedures. New macro photographs showing the bearings, bearing diameters, impeller diameters, spindle lengths, turbine jets, exhaust ports and general build quality of the tools will be shown. In the mean time, here are the results we have right now:
Shofu Lab Air-Z
1Max PSI/Bar is the recommend air pressure supplied to the carver per the manufacturer's specifications. If you watched the video for air flow measurements, the pressure displayed on the digital pressure regulator is in megapascals (MPa). 2CFM/Lpm is a measure of how much air is flowing through the turbine. If you watched the video for air flow measurements, the digital mass flow meter displays in liters per minute (Lpm). 3Turbine rebuild price / New nosecone assembly with new turbine. 4Larger number is better - F3Q is a qualitative score for Form, Fit, Function and Quality. A perfect score would be 20. 5Turbine may not be covered or limited by the warranty. 6Prices were determined by Google searching and prior pricing sheets.
RPM @ Max PSI
Loudness - dB(A) 18"
1.8oz / 52g
1.4oz / 40g
2.5oz / 70g
3oz / 83g
2.2oz / 61g
3.3oz / 94g
0.6oz / 16g
Spindle Length (mm)
Bearing Spacing (mm)
Bearing Diameter (mm)
Impeller Diameter (mm)
$349 (400xs $550)
Read the Reviews
In late 2009, research and development of a Vortex carver was begun. Debbi LerMond, a lifelong sculptor, had a list of requirements for the design engineers to meet. Debbi's carver was going to be designed for carving, not dental procedures. After 7 years of hard work, Debbi got her perfect carver and named it the Vortex F5.
SCORE: Form=5, Fit=5, Function=5, Quality=5, Total=20 out of 20.
The Vortex XJ7 by Unbridled was discontinued and replaced by the Vortex F5.
SCORE: Form=5, Fit=4, Function=5, Quality=5, Total=19 out of 20.
The NSK Nakanishi Inc, Presto is a grinder designed for processing small precision parts, ceramic, correction of printed circuit boards and dental labs. The Presto maximum pressure is 36 PSI producing 324,000 RPM. This tool works well but requires twisting the housing to remove the bur. The power output is good, but it is at most a very expensive handpiece.
SCORE: Form=3, Fit=4, Function=4, Quality=5, Total=16 out of 20.
The Shofu Lab Air-Z is a handpiece designed for the dental lab for fast, easy cutting of anatomy of porcelain and alloys in the dental industry. The Lab Air-Z maximum pressure is 36 PSI producing up to 329,000 RPM. This tool uses a small diameter turbine and lacks power. The turbine is expensive to replace.
SCORE: Form=4, Fit=4, Function=3, Quality=4, Total=15 out of 20.
Powercrafter was manufactured by Cirrus Industries, but was relabeled as the Power Pen from Paragrave a/k/a Paragraphics. Both companies use the same addresses and email contact.
The Powercrafter varies in weight from 60 grams to 86 grams from a sampling of our stock. We are not sure why the weight varies, but they said they are made out of stainless steel, yet a magnet did stick to the side of tool. So we are not sure about the quality of stainless steel alloy used.
Although the tool comes in two versions, the Polyimide bearing retainers for up to 400,000 RPM or the Phenolic bearing retainers for up to 500,000 RPM. We did not notice any difference in performance or speed between the 400,000 RPM and the 500,000 RPM models from Powercrafter. We did measure the actual RPM of the PI version which came in at 284,000 RPM @ 45 PSI. Powercrafter also said the Phenolic bearing retainers last 20% longer. We didn't notice the 20% during actual carving. We, at one time, offered both for sale because the manufacturer offered both. We sold a lot of 500,000 RPM Powercrafters. The "500,000 RPM" was more of a "product name" rather than a specification.
Our main concern with the Powercrafter was delays in getting turbines. The turbine has real impellers, larger than the Turbocarver, but smaller than the Power Carver. There is wasted area around the turbine for blow-by, but the tool works reasonably well. The bearings on either side of the turbine are directly exposed to compressed air. This requires more frequent oiling (about every 20-30 minutes) because the compressed air is blowing oil out of the bearings. A better approach would have been to place the turbine impeller on the end near exhaust port and the bearings near the bur port. This would reduce the compressed air blowing the oil out of the bearings. Difficulty comes when you need to replace the worn out turbine. As shown in the photo, a 6mm wrench is required to remove the tip coverplate. You need jewelers needle nose pliers to remove the turbine/bearing assembly from the housing. The wavy washers are incredibly small and if you are not careful, you will lose them easily. The turbine will not work properly without them. Reassembly requires careful attention NOT to cross thread the tip coverplate.
SCORE: Form=4, Fit=2, Function=4, Quality=4, Total=14 out of 20. Since the Powercrafter company is out of business, replacement turbines cannot be found.
We are sorry to report that after selling the SCM Power Carver 400K and 400XS for almost 5 years, we decided to discontinue the entire product line in early January 2015 due to quality issues with their carver. Some Power Carvers were literally falling apart. We received tools back from customers with failures with only a few hours of use. Failures included the brass manifold inserts coming out, plunger caps unscrewing, plunger E-clips breaking from forcing the plunger down too hard causing misalignment with the manifold/spindle, spindle and factory new turbine assemblies falling out of the carvers and hose barbs detaching from the air tube.
SCM's 400xs carver comes in two versions. First one is a branded Shofu Lab Air-Z dental lab handpiece. The second version looks like the entry level carver, but has the bulge on the housing like the Shofu Lab Air-Z. The second version uses the same Ney Hurricane type turbine cartridge as the entry level carver (they both use the same turbine cartridge.)
Even though we discontinued selling the Power Carver tool, it is still available from the manufacturer. For people still considering purchasing the Power Carver, here are the RPM specs for the non-Shofu Lab Air-Z: running at the original recommended pressure of 45 PSI, the RPM is about 340,000.
Since we have made it public that our findings from the bearing manufacturers stated not exceed 38 PSI for greased bearings, we have learned SCM has recently included new instructions to not exceed 37 PSI with their 400xs handpiece. We are not sure whether this is just coincidence or not but it was an interesting development that after 26 years of recommending the use of 45 PSI they now change it to 37 PSI. With this development, the new RPM at 37 PSI is 304,000.
SCORE: Form=3, Fit=2, Function=3, Quality=2, Total=10 out of 20.
Photo below of SCM Power Carver with brass insert falling out and failed turbines. Also, new 400xs instructions saying never to exceed 37 PSI.
The Turbo Carver weights in at 14 grams and is billed as "The World's Fastest & Lightest Power Carving Tool" but unfortunately has the least amount of power of the 6 major contenders in this comparison. Power, called torque, is what gives the tool its cutting ability, not RPM (speed). We consider this carver to be a "hobby grade" plastic turbine tool. First thing we noticed was how loud it is (consider ear protection). Since the turbine is so small, it slows down considerably when carving from the actual measured speed of a brand new Turbo Carver. At the manufacturer's recommend air pressure of 45 PSI, the RPM is 387,000. That changes quickly once the bur makes contact with the work surface. This is due to the carver's low mass impeller and stall torque of 690 gcm - 3.0 Ncm thus producing a slow angular velocity (rotational speed) of 180,000 to 200,000 RPM under load. Running the Turbo Carver at 45 PSI will shorten the lifetime of the bearings considerably as major dental bearing manufacturer's recommended maximum pressure is 38 PSI. The torque and speed measurements are from the Turbo Carver website (April 15th, 2017).
A firm grip is required to control the Turbo Carver because it is so lightweight and small. When a bur grabs your work, it might want to "walk" along the work surface during tooling if a very firm grip is not used. The length of the Turbo Carver is quite short requiring almost a pinch-like grip to fit in the average adult's hand. The plunger and hose are right up against the hand in an uncomfortable position as can be seen on the Turbo Carver website. Another reason for the pinch-like grip on the Turbo Carver is the pinch valve hose near the snout of the handpiece does not allow the user to grip the tool like a normal pen or pencil. Pinching the tool with your thumb and fingers can lead to cramping, numbing fatigue, not good if you have Carpal Tunnel Syndrome. Because the length of the Turbo Carver is so short, the plunger can rub on the side of the user's skin. As a former Turbo Carver user, these results were experienced first hand. The current length does not fit a normal adult hand well.
Looking at the photo above of the Turbo Carver, you can see how the air hose loops away and back towards the front of the tool. This causes all kinds of problems when trying to see your work and it makes it very difficult to get into tight places. The hose just gets in the way. We had many customers telling us about black material coming out of the tool and others returning their tools to us for refunds because their Turbo Carvers would stop turning, sometimes in less than an hour after the initial set up.
A review of their patented 6,146,137 (click to view) talks about the plastic injection molding process to make the tool and the internal molded plastic turbine impeller, it also indicates the PVC pinch anti-contamination device is used for oiling the tool. Here is what the patent says "In the present invention, an aerosol lubricator, similar to WD40 is used by squeezing an exhaust port with the fingers to make the tubing round and then inserting the aerosol tip into the exhaust stack while pressing the plunger once (the WD40 plunger). This applies a metered amount of lubrication directly into the turbine bearings, saturating them." Yet, the Turbo Carver website says "Lube Free - No Oil Required" (April 15th, 2017). Could this be why the tool stopped turning because their ABEC scale 7 bearings were starved for oil? Note about Turbo Carver bearings: the ABEC rating they use does not specify many other critical factors, such as smoothness of the rolling contact surfaces, ball precision, and material quality.
Our conclusion for the tool's poor reliability was due to the ABS plastic construction and unlubricated small paddle wheel turbine and ABEC 7 bearing assembly. The black material was caused by the turbine/bearing assembly making contact with the plastic housing (see wear damage in photo). This black plastic dust is circulated in the housing and easily finds its way into the bearings causing the tool to eventually stop. The Turbo Carver comes with a surprisingly short 6 month warranty and is exceedingly expensive for a plastic tool.
SCORE: Form=1, Fit=2, Function=2, Quality=1, Total=6 out of 20.
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