Test of 3 Types of Rollers for Benchtop Thickness Planers

We’ve conducted an in-depth test of three types of thickness planers with different cutterhead designs and compared the key differences. Do straight and spiral cutterheads truly differ, and are they really that much better than the standard two-knife cutterheads? If you’re wondering which would be the best fit for your workshop, you’ll find the answer here.

We will be comparing the traditional knife cutterhead, a helical cutterhead, and a spiral cutterhead, focusing on differences in noise levels, knife overlap, durability, and overall cost relative to blade lifespan. Most importantly, though, we’ll be examining the quality of the wood finish, as that’s the top priority.

Cutterhead 1: Machine 1

Cutterhead 2: Machine 2

Cutterhead 3: Machine 3

The helical cutterhead is becoming increasingly popular among woodworkers, but it’s also a widely debated topic, often surrounded by half-truths. That’s why we decided to conduct a detailed test for you. In this test, we will examine differences in finish quality, calculate blade and insert lifespan, measure and compare machine noise levels, and show you that not all helical cutterheads may be what you’re actually looking for.

The Machines Tested:

1. Thickness Planer (Machine 1): JET JWP-12 with a traditional two-knife cutterhead with HSS blades.
2. Thickness Planer (Machine 2) with a helical cutterhead fitted with HSS inserts.
3. Thickness Planer (Machine 3): IGM PS33 with a spiral helical cutterhead fitted with carbide (HW) inserts.

Machine 1

The JET JWP-12 machine has two single-sided HSS blades, typically with a hardness around HV10 600 on the Vickers hardness scale. These blades cannot be rotated after dulling.

Machine 2

This machine has a helical cutterhead with 26 HSS inserts, also with a hardness of about HV10 600, which can be rotated once.

Machine 3

The IGM PS33 planer has a spiral helical cutterhead with 36 carbide inserts at a hardness level of HV10 1900, and each insert can be rotated up to three times.

The main claimed benefits of helical cutterheads over traditional knife cutterheads are longer blade life and high-quality wood finish. We will test whether this is indeed the case.

1900 HV10 vs. 600 HV10 = ratio 3.1:1

Carbide is therefore up to three times harder than standard HSS steel and stays sharp up to three times longer.
From this, it follows that the blades in the IGM PS33 will have the longest lifespan.

Blade and Insert Lifespan

In the next calculation, we’ll show you precisely how much longer the lifespan of these blades will be, considering additional parameters.

JET JWP-12

Machine 1

IGM PS33

Machine 3

In comparison to the first machine, the JET JWP-12, which has only two traditional HSS knives, the IGM PS33 features blades made from a material with up to three times greater resistance to dulling, and they can also be rotated three times after becoming dull. However, the JET planer has two knives engaged over every 1 cm of board, meaning their total dulling is evenly distributed between the two edges.

In the IGM PS33, there is 1.5 inserts engaged over every 1 cm of board. This means that the resistance of the cutting edges is 25% higher compared to the JET machine.

The overall calculated lifespan of the cutting edges in the first machine is 9 times shorter than that of the PS33. However, we must add the 25% advantage of the two knives. In summary, the calculated lifespan of the inserts in the PS33 compared to the two traditional HSS knives is 6.7 times higher in favor of the PS33.

In practical terms, this means that if you want to achieve the same knife lifespan with the first machine as with the PS33, you will need to sharpen the knives at least 7 times by that point. With two knives that are 318 mm wide, one sharpening costs approximately 12 €. Therefore, the costs to equal the lifespan of the PS33 inserts are 84 €.

Machine 2 with Helical Cutterhead

Machine 2

IGM PS33

Machine 3

Now let's take a look at the lifespan of the inserts in the traditional helical cutterhead of the second machine. The spiral cutterhead of the PS33 has more inserts, which is an advantage due to greater overlap of the inserts. Furthermore, these inserts are three times more resistant than the HSS inserts of the second machine, which can only be rotated once and not three times like those in the PS33. In summary, the HSS inserts in the second machine last up to six times less. The thickness planer PS33 with a spiral cutterhead benefits from half the overlap of the inserts, which increases the overall lifespan of the knives in the PS33 by 50%, making it nine times higher.

This means that with HSS inserts that can only be rotated once, to achieve the same lifespan as in the PS33, you would need to purchase nine sets of inserts, each containing 26 pieces. At a price of approximately 4 € per HSS insert, this amounts to a total cost of 936 €.

Neither carbide nor HSS inserts are sharpened, as the cost of sharpening is roughly equivalent to the price of a new insert. Additionally, sharpening would reduce their dimensions, leading to insufficient overlap, which would leave marks on the surfaced board.

Quality of Finish

Machine 1

JET JWP-12 with Two-Knife Cutterhead

It has a motor with a power output of 1700 W, and the cutterhead rotates at a speed of 10,000 RPM. Both the power and the RPM are ideal for this machine. However, since the planer knives are set at a 90° angle to the material feed, the knife always engages the wood along its entire length. The knives create significant resistance against the motor, which limits the maximum material removal to 2.4 mm.

When inspecting the workpiece against the light or highlighting the surface quality with a pencil, both longitudinal and transverse marks from the planer knives are clearly visible. Additionally, knots in the material are slightly chipped. A board planed in this manner will require repair or filling of the knots and should be sanded at least once.

Machine 2

Thickness Planer 1800 W with Traditional Helical Cutterhead

The second machine has a power output of 1800 W, which is 100 W higher than the JET machine, and the same cutterhead speed of 10,000 RPM. Its inserts are not arranged in a spiral but are perpendicular to the feed axis. Although four inserts engage the wood, not all do so simultaneously, which reduces the resistance against the motor. However, knots still become chipped, and there are visible marks left by the inserts on the board.

Material planed with this machine will also need repairs or filling and should be sanded at least once more.

Machine 3

IGM PS33 with Spiral Helical Cutterhead

The IGM PS33 has the same motor power as the second machine, at 1800 W, but has 1,000 fewer RPM, with a speed of 9,000 RPM. It is the only machine tested that features inserts arranged in a spiral, angled to the axis. This offers significant advantages in finish quality, compensating for the lower cutterhead speed.

The resulting surface of the boards planed on this machine is completely smooth, with knots nicely cut and not chipped. This is thanks to the spiral arrangement of the inserts, their rounded shape, and the overlap of the inserts. The inserts on the spiral cutterhead engage the material gradually. This not only significantly reduces resistance against the motor but also mainly reduces resistance against the wood fibers, which are not sheared off like with perpendicular knives but are gradually sliced. As a result, this machine can achieve a material removal of up to 3.2 mm.

The more the resistance of the knives against the material is reduced, the better the quality of the finish, and the sharper the inserts will remain for longer. However, we won’t factor this into the previous calculations.

Noise Measurement

It is often stated that helical cutterheads are very quiet compared to knife cutterheads. Therefore, we decided to substantiate this claim by measuring the acoustic load of the three tested machines using a digital sound level meter. Although the noise level of the machine does not affect the quality of wood processing, it significantly impacts comfort during work.

We conducted noise testing at idle, which is the standard procedure for measuring the acoustic performance of machines. Each machine was measured for 10 seconds after being turned on, and the measured continuous values were then averaged.

Machine 1

JET JWP-12

We measured 102 dB, which more or less corresponds to the value in the manual, where the manufacturer states 101.5 dB.

Machine 2

Thickness Planer 1800 W

The measured value of 97 dB is 2 dB higher than the value in the manual. However, considering that we do not have laboratory conditions here, we can regard this as a true figure.

Machine 3

IGM PS33

Here we measured 96 dB, which matches the value from the manual.

Thus, the quietest machine was the PS33, followed by the machine with the HSS helical cutterhead, and in third place was the JET machine with the traditional cutterhead.

There is a difference in the noise load generated during the rotation of the helical cutterhead compared to the knife cutterhead. While the spiral cutterhead expels air through grooves, a certain amount of air is trapped in the space for the key on knife cutterheads, which is then pushed forward during rotation and forced perpendicularly to the axis. When this air hits an obstacle, it creates noise.

You can see that both machines with helical cutterheads have nearly the same noise levels, which are about 5-6 dB lower than that of the machine with the traditional cutterhead. However, in practice, the noise from all three machines is very similar. Therefore, even in the case of the least noisy machine, the use of hearing protection equipment cannot be overlooked.

The noise levels of all the benchtop thickness planers are quite similar since the main source of noise is the carbon motor. Brushless motors of this power and size are not yet manufactured. However, if it were a classic planer or a large industrial thickness planer with an induction motor, we would measure values up to 20% lower with the spiral helical cutterhead.

Spiral Cutterhead in Machine PS33 is TOP

In the table below, you will find a complete summary of the results of the individual tests and measurements. From the provided data, it is clear that the absolute winner is the benchtop thickness planer IGM PS33 with an innovative spiral helical cutterhead, which not only has the best quality of workpiece processing and depth of cut, but also has the longest lifespan and the lowest operating costs. In terms of noise, it is slightly, but still wins.

	Knife Overlap per cm	Number of Knives	Hardness according to Vickers	Knife Rotation Possibility	Times Lower Lifespan Compared to TOP Machine	Sharpening or Blade Cost	Total Cost of Knives Compared to TOP Machine	Acoustic Power Level	Surface Quality of Processed Wood	Ranking: 1 Best
Machine 1	2x	2x HSS	600 HV10	0x	6.77x	12 €	84 €	102 dB	2	2
Machine 2	0x	26x HSS	600 HV10	1x	9x	4 €	936 €	97 dB	3	3
Machine 3	1.5x	36x carbide	1900 HV10	3x	TOP	4.60 €	TOP	96 dB	1	1

In second place was the JET JWP-12 machine with a conventional knife cylinder, and in last place was the machine with a knife cylinder with perpendicular HSS knives. Although it also uses blade technology like the winning planer, the combination of perpendicular blades and their construction from HSS steel makes this machine the most expensive to maintain and sharpen, while providing very average to below-average wood processing quality. Therefore, if you are considering purchasing a new thickness planer, the IGM PS33 is clearly the first choice.