Round-Shaped vs. Hexagonally Shaped Saw Chain: Cutting Efficiency and Vibration Comparison

Abstract

Despite advances in technique and technology, the chainsaw is still the most widely used tool in forestry. For this reason, equipment manufacturers are developing new technical solutions to make working with a chainsaw as easy and efficient as possible. Some examples of this are the development of professional battery-powered chainsaws and the development of new types of saw chains by the leading industry manufacturers. The aim of this paper was to determine the efficiency of the Stihl MSA 300C battery-powered chainsaw equipped with two different types of professional saw chains (Stihl Rapid Super and Stihl Rapid Hexa) when sawing round wood. The efficiency was determined based on measurements of electricity consumption, sawing speed, sawn wood cross-section, and wood chips and dust mass produced during sawing. The second aim was to determine whether there is a difference in measured vibration magnitude between the two tested saw chains. Fresh-fallen European beech (Fagus sylvatica L.) log, approx. 25 cm diameter without pronounced ellipticity, was used for sampling. Results indicate that although the saw chain manufacturer claims the new type of saw chain (Stihl Rapid Hexa) enables greater efficiency of the chainsaw, this was not the case. Results point to a 37% increase in mean sawing time, as well as a 23% increase in energy consumption when using the Rapid Hexa chain, with statistically significant difference (p ≤ 0.05). It should be emphasized that the manual operation of the chainsaw does not allow for a reliable determination of differences in energy consumption caused by changes in saw chain geometry. The advantages of this saw chain are that it is easier to maintain (sharpen) and significantly less wood chips and dust are produced. The measured vibration magnitude shows a statistically significant difference (p ≤ 0.05), i.e., a lower vibration total value on the front handle when using the Stihl Rapid Hexa chain.

1. Introduction

The relentless pursuit of enhanced performance and operator comfort in handheld power tools has spurred significant advancements in chainsaw technology. This evolution is particularly evident in the professional forestry sector, where the demand for lightweight, efficient, and ergonomically sound equipment is paramount and highly investigated. Innovations like improved chainsaw propulsion and adjustments in saw chain geometry create opportunities for further advancements in this segment of the forestry industry. Hence, battery-powered chainsaws offer several advantages, including reduced vibration [1,2,3] and noise [4,5,6] pollution, lower emissions [7,8], performance comparable to petrol counterparts [4,7,9], and energy efficiency [10], making them attractive alternatives to traditional gasoline-powered models. However, understanding their operational characteristics, particularly concerning sawing efficiency and vibration levels, is crucial for optimizing their application in demanding professional settings. The intricacies of power utilization in battery-powered chainsaws necessitate a comprehensive understanding of the energy expenditure associated with various operational aspects, encompassing sawing, frictional losses, vibration, chip removal, and parasitic loads, which are all critical factors in the design of effective and energy-efficient tools [11].

Furthermore, the selection of the appropriate saw chain plays a pivotal role in determining the overall performance of the chainsaw, directly influencing sawing speed, energy consumption, and the levels of vibration transmitted to the operator. Different chain designs exhibit varying cutting geometries, tooth configurations, and material properties, all of which can significantly impact their interaction with the wood and, consequently, the chainsaw’s efficiency and also safety [12]. Some authors have found that the average efficiency of cross-cutting is significantly lower than when using a blunt chain [7]. The sharpness of the chain is certainly an important factor for sawing efficiency; however, the friction between the saw chain and the bar, along with chain vibration, is also important [11]. Warguła et al. [13] report, in their analysis of the force and durability of the blade on the machines that split and cut wood without creating chips, that a blade with a tip angle of 30–45° was an efficient solution. Another study by Otto and Parmigiani [14] determined that the optimum efficiency for saw chain cutting exists and that it occurs at the depth-of-cut equal to the overload depth-of-cut value; also, it concluded that the optimum efficiency occurs at the 60 N feed force, which is approximately equal to the weight of the typical battery-powered chainsaw. Furthermore, the same authors [15] reported that under all sawing conditions, the professional saw chain demonstrated the lowest cutting forces and consequently the highest sawing efficiencies in comparison to the three low-kickback chains that were tested. However, the researchers emphasize that a key challenge in low-kickback chain design is parameterizing the link shape in a way that enables controlled design iteration—essentially determining the relationship between cutting forces and link geometry. To fully leverage the potential of battery-powered chainsaws, it is essential to conduct rigorous testing and analysis of different saw chain types under controlled conditions. This approach enables the identification of optimal chain configurations that maximize sawing performance while minimizing energy consumption and vibration. Investigating the energy intensity of the saw chain mechanism during operation, particularly when sawing common wood types such as spruce, provides valuable insights into the relationship between cutting speed, feed rate, and power requirements [16]. By meticulously measuring these parameters, it becomes possible to quantitatively assess the efficiency of different chain designs and pinpoint the factors that contribute to energy losses.

According to several studies, the design of the cutting teeth and the sharpness of the chain can affect vibration levels. Jakubek and Rukat [17] found that vibration measurements on the front handle were on average 30% higher for a semi-chisel chain compared to a full chisel chain. However, they acknowledged that their chosen measurement methodology did not provide clear and precise means to determine the influence of chain wear on the vibration levels in chainsaw handles. Kováč et al. [18] conclude that the type of saw chain does not have an influence on the size of vibrations. Conversely, Rottensteiner and Stampfer [19] observed significantly higher vibration values when using a blunt chain. The directionality of the cutting kerf, arising from the heterogeneous cellular structure of wood and the anisotropy of its mechanical properties, can influence vibration acceleration and emitted noise [20]. The assessment of vibration levels is an indispensable aspect of evaluating chainsaw performance, given the well-established link between prolonged exposure to hand–arm vibration and various musculoskeletal disorders [21]. Chainsaw operators are particularly vulnerable to these risks, underscoring the importance of minimizing vibration transmission through the implementation of effective vibration-damping technologies and ergonomic design principles. The intensity of vibro-acoustic impact on chainsaw operators depends on many factors, including saw design [22]. Investigating the vibrational characteristics of chainsaws necessitates the use of advanced measurement techniques, such as accelerometers strategically placed on the tool’s handle, to capture the frequency and amplitude of vibrations during operation. The investigation of how different saw chain types impact the vibration characteristics of battery-powered chainsaws is, therefore, a critical area of research, as minimizing vibration exposure is paramount to protecting the health and safety of operators.

Moreover, understanding the vibration characteristics of battery-powered chainsaws is crucial for mitigating the risk of hand–arm vibration syndrome, a debilitating condition that affects many professional chainsaw operators. Vibration magnitude and exposure are influenced by several factors, including the chainsaw’s characteristics, the saw chain type and sharpness, and the wood’s density and grain structure [23]. The complex interplay of factors influencing vibration necessitates a comprehensive analysis of chainsaw operation, considering the chain’s design, the wood properties, and the dynamic forces generated during sawing, to minimize operator fatigue and health risks.

This paper aimed to investigate the influence of two types of commercially available professional saw chains on the overall efficiency and vibration levels of a battery-powered chainsaw in a controlled environment. The purpose of this research was to objectively compare the newly developed Stihl Rapid Hexa chain, which utilizes hexagonally shaped cutting teeth, with the more commonly and widely used Stihl Rapid Super chain. The Stihl Rapid Hexa chain is advertised as a “professional”, “high-performance”, “long-life”, and “low-vibration” chain [24]. Some sites even advertise 10% faster sawing compared to the Rapid Super chain due to narrower kerf [25]. In that regard, Marenče et al. [26] emphasize the lack of qualitative data to support the producers’ statements and conclude that brand loyalty surpasses rational thinking. By employing a combination of experimental measurements and data analysis techniques, this research seeks to provide insights into the performance characteristics of the two mentioned saw chain designs and their implications for operator comfort and safety. Although battery-powered chainsaws are currently not the primary choice for professional loggers, arborists, and forestry workers, their advantages over petrol-powered saws are becoming more apparent. It is safe to predict that future chainsaw propulsion will probably be replaced with a more efficient one. For that reason, and because battery-powered chainsaws are simple and very suitable for controlled experiments, this study utilizes a battery-powered chainsaw to investigate the vibrations and cutting efficiency of different saw chain designs.

2. Materials and Methods

2.1. Research Objects

In this research, a Stihl MSA 300C battery chainsaw with an AP500S battery (

Table 1. Chainsaw and battery characteristics.

Chainsaw Type	Mass 1	Max Power Output 2	Bar Length	Chain Speed 3
Stihl MSA300C	4.5 kg	3.3 kW	45 cm	20; 24; 30 m/s
Battery Type	Mass	Nominal Voltage	Capacity (Ah)	Capacity (Wh)
Stihl AP500S	2 kg	36 V	8.8 Ah	337 Wh

¹ without battery, bar, chain, and oil; ² measured during the test; ³ values for three operating modes.

) in felling mode (24 m/s chain speed) was used.

Since the issued sprocket for this chainsaw had 6 teeth and a 0.325″ chain pitch, for the purposes of this research, the chainsaw was fitted with a 7-tooth sprocket, essentially converting it to a 3/8″ chain pitch. The primary reason for this modification was to facilitate testing of 3/8″ professional saw chains commonly used in the forestry industry. The chain speed was not affected by this conversion, which was confirmed by measuring the chainsaw RPM using a laser tachometer and utilizing the chain speed equation (Equation (1)). The tachometer measured 11,000 rpm in the felling mode. Smaller-chain-pitch (0.325″) chains are considered to perform smoother cuts, and are used on smaller guide bars. This may affect the vibration values, but the conversion to 3/8″ chain pitch was necessary in order to perform a fair comparison. A micrometer was used to measure the cutter tooth width.

$$v=cp\times 2\times nt\times rpm\times 0.00042333 [\mathrm{m}/\mathrm{s}]$$

(1)

v—chain speed; cp—chain pitch; nt—number of teeth on a sprocket; rpm—revolutions per minute; 0.00042333—conversion value for converting inch/min to m/s.

During the tests, two different saw chain types were used (Figure 1), both full-chisel, the Stihl 3/8″ Rapid Super and the Stihl 3/8″ Rapid Hexa, on a 45 cm bar. Comparison of the chain characteristics can be observed in

Table 2. Saw chain characteristics.

Chain Type	Chain Pitch	Chain Gauge	Number of Drive Links	Cutter Shape	Cutter Width	Sharpening Angle	File Shape
Rapid Super	3/8″	0.063″	66	Full chisel	4.5 mm	30°	Round
Rapid Hexa	3/8″	0.063″	66	Full chisel	4.1 mm	25°	Hexagonal

. The Rapid Hexa chain is considered to have a narrower kerf in comparison to the Rapid Super chain [25].

It should also be noted that the file issued with the Rapid Hexa chain is easier and safer to operate since it requires proper positioning to perform the filing. More precisely, only four sides of a hexagon are used for sharpening, while one side is required to always face upward. The opposite side (downward side) has a smooth finish and does not remove material, which means that there is no danger of accidentally grinding into the joining link.

The Stihl Rapid Super chain represents an industry-standard, high-performance saw chain known for its sharp cutting edges and efficient wood removal capabilities. The Stihl Rapid Hexa chain features a distinctive hexagonal cutter shape, designed to maintain sharpness longer and deliver improved sawing performance compared to conventional chains. Both chains were brand new with original untouched depth gauges.

Sawing efficiency and vibration magnitude were measured on a fresh-fallen European beech (Fagus sylvatica L.) log, approx. 25 cm diameter without pronounced ellipticity. The beech log was supported by a sawhorse, ensuring consistent and stable sawing conditions throughout the experiment. The measurements were conducted at the TFRC (Training and Forest Research Center) Zagreb. For efficiency purposes, each chain was subjected to 30 cuts under principally identical conditions, allowing for a comparative analysis of sawing speed (duration) and battery (energy) consumption. To assess the energy consumption per cut, a Pichler C7282 multimeter (Pichler Modellbau GmbH, Eggenfelden, Germany) was connected to the positive and negative terminals of a Stihl AL300 charger housing (ANDREAS STIHL AG & Co. KG, Weinsheim, Germany), powered by an external battery. The load side of the multimeter was connected to the lead wires of an original Stihl connecting cable, with a Stihl AP adapter supplying power to the chainsaw. Two additional signal wires necessary for the chainsaw’s operation were directly connected to the Stihl AL300 housing pins. Inserting batteries into the Stihl AL300 housing powered up the chainsaw. The multimeter provided instantaneous measurements of voltage, amperage, and electric power, as well as cumulative amp-hours and watt-hours over time under load. The energy consumption for each cut, expressed in watt-hours (Wh), was then calculated using a simple subtraction in Microsoft Excel^® (Version 2311). This method was established in the previous research [10]. The chainsaw sawing speed was assessed utilizing a GoPro^® camera (GoPro Inc., San Mateo, CA, USA). Video recordings were captured at a frame rate of 60 frames per second and subsequently analyzed using VLC media player^® (Version 3.0.14). The duration of each cut was recorded in centiseconds. This data was later converted to seconds in Microsoft Excel^® for further analysis. Two diameters in a cross pattern were measured for each cut part of the log. Afterwards, the mean diameter was calculated, as well as the sawn area in m². This enabled the energy and time spent in relation to the sawed surface area to be determined. An effort was made to saw using the same technique each time, without exerting additional feed force other than the chainsaw’s mass, and an additional metal piece was mounted at the top of the bar to ensure more constant feed force since the chainsaw was missing its battery (mass of 2 kg). Additionally, the weight of the total wood chips/dust ejected during the 30 cuts for each chain was measured by using a Mark-10 dynamometer (Mark-10 Corporation, Copiague, NY, USA). The chips were collected on a tarp placed beneath and around the sawhorse (Figure 2).

Vibration measurements were executed concurrently with the efficiency measurements, utilizing a sample size of 15 cuts per chain/handle combination. There were a total of 30 cuts per handle sample to satisfy the academic “rule of thumb” for t-test sample size. The measuring equipment adhered to the ISO 8041:2017 [27] standard. A four-channel Brüel & Kjaer LAN-XI Type 3676-B-040 (Brüel & Kjaer, Nærum, Denmark) module was employed in conjunction with a triaxial accelerometer, model 4524-B-001 (Brüel & Kjaer, Nærum, Denmark), and a UA 3017 mount (Brüel & Kjaer, Nærum, Denmark). The accelerometer was affixed using plastic ties and strategically positioned in proximity to the operator’s hand, specifically, to the right of the hand on the front handle and behind the hand on the rear handle. A laptop computer, running designated software, managed the measurements via a Wi-Fi connection to a router. The LAN-XI module and its associated router necessitated external batteries for operation. A backpack was utilized to accommodate the measuring equipment. The guidelines stipulated in ISO 5349-1:2001 [28] and ISO 5349-2:2001 [29] standards, pertaining to aspects such as measurement organization, vibration measurement duration, work procedure simulation, accelerometer placement, accelerometer attachment, and uncertainty evaluation, were rigorously observed during the measurements. The instrument was calibrated prior to the commencement of measurements. Vibration magnitude was expressed as vibration total value (VTV) according to Equation (2).

$$VTV=\sqrt{a_{hwx}^2+a_{hwy}^2+a_{hwz}^2}$$

(2)

a_hwx; a_hwy; a_hwz—root-mean-square acceleration magnitude measured in three orthogonal directions, x, y, and z, at the vibrating surface in contact with the hand and frequency-weighted using the weighting Wh.

Statistical analysis was conducted in STATISTICA^® (version 14) and Microsoft Excel^® (Version 2311), and after testing the data for normality and homogeneity of variance, parametric tests were used in further analysis. Descriptive statistics were utilized to give a general overview of the measured variables. Afterwards, a paired t-test (p ≤ 0.05) was chosen to test the significance of differences between the two chain types in terms of the variables that were measured. Furthermore, a regression analysis (p ≤ 0.05) was performed to predict the relationship of certain variables with other ones.

2.2. Research Limitations

The efficiency and vibration of sawing with a chainsaw are influenced by numerous factors, and it is difficult to achieve identical measuring conditions when investigating a single influential factor (in this study, the chainsaw chain). The biggest limitation of this study is human error, since a person was operating and handling the chainsaw, and not a laboratory-grade testing stand. The method of collecting wood chips and dust using a tarp was susceptible to external influences. Furthermore, wood is a natural material that is rarely of a homogeneous structure, a fact that surely influences the efficiency and vibration figures. Along with that, the dimensions of the wood sample were not standardized, resulting in slight dimensional differences in every cutout (sample). Also, the wood moisture content, which can significantly influence the efficiency and vibration values, was not taken due to the assumption that it is the same on both ends of the fresh-fallen wood and the fact that relative values are considered in this study, rather than absolute ones. However, efforts were made during the study to ensure the measuring conditions were as consistent as possible.

3. Results and Discussion

3.1. Measurement Values and Data Overview

Table 3. Rapid Super measurement values.

Cutout Number	E (Wh)	D1 (mm)	D2 (mm)	μ D (mm)	A (m2)	T (s)	E/A (Wh/m2)	T/A (s/m2)	VTV-F (m/s2)	VTV-R (m/s2)
1	6.3	257	224	240.5	0.0454	7.44	138.68	163.78		3.16
2	6.3	256	221	238.5	0.0447	7.91	141.02	177.06		3.10
3	6.2	256	220	238	0.0445	7.76	139.36	174.43		3.06
4	6.7	256	219	237.5	0.0443	8.17	151.24	184.42		3.06
5	6.1	257	218	237.5	0.0443	6.47	137.69	146.05		3.16
6	6.5	257	217	237	0.0441	7.35	147.34	166.61		3.29
7	7	256	217	236.5	0.0439	8.45	159.35	192.36		2.74
8	5.8	256	217	236.5	0.0439	8.01	132.03	182.34		2.92
9	5.3	254	215	234.5	0.0432	6.77	122.72	156.75		3.4
10	5.1	255	216	235.5	0.0436	6.59	117.08	151.29		3.23
11	5.7	256	217	236.5	0.0439	6.76	129.75	153.88		3.48
12	5.6	255	215	235	0.0434	7.91	129.11	182.37		2.48
13	5.7	255	214	234.5	0.0432	7.21	131.98	166.94		3.21
14	4.3	256	160	208	0.0340	5.01	126.55	147.44		1.91
15	5.9	257	217	237	0.0441	6.74	133.74	152.78	4.28
16	4.8	258	215	236.5	0.0439	5.21	109.27	118.60	3.19
17	5.1	258	215	236.5	0.0439	5.46	116.10	124.29	3.25
18	5.4	260	215	237.5	0.0443	6.27	121.89	141.53	3.03
19	5.7	259	214	236.5	0.0439	5.75	129.75	130.89	3.62
20	5	262	214	238	0.0445	6.01	112.39	135.09	3.23
21	4.7	261	213	237	0.0441	5.50	106.54	124.67	3.11
22	4.2	262	213	237.5	0.0443	5.25	94.81	118.51	3.32
23	5.5	261	213	237	0.0441	6.10	124.67	138.27	3.48
24	5.7	262	214	238	0.0445	5.93	128.12	133.29	2.84
25	4.7	258	211	234.5	0.0432	5.71	108.82	132.21	3.19
26	5.8	259	215	237	0.0441	6.77	131.47	153.46	2.72
27	5.7	258	221	239.5	0.0451	6.10	126.52	135.40	2.85
28	4.9	258	228	243	0.0464	5.99	105.66	129.16	3.01
29	6.7	258	230	244	0.0468	6.93	143.29	148.21	2.94
30	5.3	258	230	244	0.0468	6.25	113.35	133.66	4.28

E—energy; D—diameter; A—area; T—time; VTV—vibration total value; F—front handle; R—rear handle.

shows measurements and their derivatives, taken with the Stihl Rapid Super chain equipped.

Table 4. Rapid Hexa measurement values.

Cutout Number	E (Wh)	D1 (mm)	D2 (mm)	μ D (mm)	A (m2)	T (s)	E/A (Wh/m2)	T/A (s/m2)	VTV-F (m/s2)	VTV-R (m/s2)
1	8.9	269	240	254.5	0.0509	11.80	174.95	231.96	2.62
2	6.6	268	239	253.5	0.0505	9.17	130.77	181.69	3.30
3	6.8	268	238	253	0.0503	9.45	135.26	187.98	2.38
4	6.7	264	235	249.5	0.0489	7.91	137.04	161.79	2.44
5	6.3	234	265	249.5	0.0489	7.75	128.86	158.52	2.62
6	7.2	267	235	251	0.0495	9.09	145.51	183.71	2.15
7	7.1	267	234	250.5	0.0493	8.74	144.06	177.34	2.35
8	7.1	268	234	251	0.0495	9.43	143.49	190.58	2.49
9	8.2	267	234	250.5	0.0493	10.76	166.38	218.33	2.35
10	8.2	268	235	251.5	0.0497	10.49	165.06	211.16	2.62
11	7.1	272	235	253.5	0.0505	9.99	140.67	197.93	2.37
12	7.5	234	271	252.5	0.0501	9.75	149.78	194.71	2.69
13	7.1	274	270	272	0.0581	8.84	122.19	152.13	2.53
14	7.3	232	232	232	0.0423	8.96	172.69	211.95	2.44
15	6.8	232	231	231.5	0.0421	7.75	161.55	184.12	2.96
16	8	272	233	252.5	0.0501	10.59	159.76	211.49		2.69
17	7.6	275	233	254	0.0507	10.26	149.99	202.48		2.66
18	7.9	268	266	267	0.0560	9.66	141.10	172.53		3.06
19	7.4	267	266	266.5	0.0558	9.69	132.66	173.72		3.35
20	7.6	230	236	233	0.0426	8.46	178.24	198.41		4.13
21	7.3	233	267	250	0.0491	9.25	148.71	188.44		3.84
22	6.7	270	226	248	0.0483	9.25	138.70	191.49		4.12
23	6.8	229	232	230.5	0.0417	8.51	162.96	203.94		3.18
24	5.3	210	226	218	0.0373	7.25	142.00	194.24		3.36
25	5.9	265	232	248.5	0.0485	7.82	121.65	161.24		3.37
26	5.8	264	226	245	0.0471	7.75	123.03	164.39		4.14
27	5.5	229	264	246.5	0.0477	6.40	115.25	134.11		2.45
28	5	264	229	246.5	0.0477	7.01	104.77	146.89		2.80
29	4.9	264	229	246.5	0.0477	9.34	102.68	195.71		4.04
30	4.9	265	226	245.5	0.0473	8.52	103.52	179.99		3.13

E—energy; D—diameter; A—area; T—time; VTV—vibration total value; F—front handle; R—rear handle.

shows measurements and their derivatives, taken with the Stihl Rapid Hexa chain equipped.

Due to dimensional differences in cutout samples, equalization was achieved in the sense that the energy and time spent sawing were expressed per sawn area in m², as shown in

Table 5. Descriptive statistics of cutting efficiency.

	Energy (Wh)		Time (s)		Area (m2)		Energy/Area (Wh/m2)		Time/Area (s/m2)
	RS	RH	RS	RH	RS	RH	RS	RH	RS	RH
Mean	5.6	6.9	6.59	8.99	0.044	0.049	127.01	141.44	149.86	185.43
Median	5.7	7.1	6.53	9.13	0.044	0.049	128.62	141.55	147.82	188.21
Mode	5.7	7.1	7.91	7.75	0.044	0.048	129.75	#N/A	#N/A	#N/A
Std. Dev.	0.7	1.0	0.96	1.21	0.002	0.004	14.71	20.80	21.05	22.40
Minimum	4.2	4.9	5.01	6.4	0.034	0.037	94.81	102.68	118.51	134.11
Maximum	7.0	8.9	8.45	11.8	0.047	0.058	159.35	178.24	192.36	231.96
Sum	167.7	205.5	197.78	269.64	1.320	1.457	3810.30	4243.29	4495.75	5562.97
Count	30	30	30	30	30	30	30	30	30	30
Weight of the wood chips and dust totaled to 123.2 N (12.56 kg) (RS) and 100.6 N (10.25 kg) (RH)

RS—Rapid Super; RH—Rapid Hexa.

. A general overview of the descriptive statistics presented in Table 5 already points to some notable trends between the two chain types. The obvious difference is in the total sawn area and total weight of the wood chips and dust. Although the total sawn area when using the Stihl Rapid Super chain was lower in comparison to the total sawn area when using the Stihl Rapid Hexa chain, the total weight of the wood chips and dust was higher, indicating that the Stihl Rapid Super is removing more material when sawing. This is in line with the advertisements of the Rapid Hexa being a narrow kerf chain [24], and it is also evident in the narrower cutter tooth width of the Rapid Hexa. It is also evident that the mean energy, time, and sawn area were somewhat greater when using the Rapid Hexa.

Table 6. Descriptive statistics of vibration magnitude.

	VTV-R (m/s2)		VTV-F (m/s2)
	RS	RH	RS	RH
Mean	3.05	3.35	3.20	2.55
Median	3.16	3.35	3.19	2.49
Mode	3.16	#N/A	3.19	2.62
Std. Dev.	0.42	0.58	0.38	0.28
Range	1.7	1.69	1.56	1.15
Minimum	1.91	2.45	2.72	2.15
Maximum	3.61	4.14	4.28	3.3
Count	15	15	15	15

VTV—vibration total value; R—rear handle; F—front handle; RS—Rapid Super; RH—Rapid Hexa.

gives insight into the vibration magnitude occurring on the chainsaw’s front and rear handles. Both the highest and lowest mean values were recorded with the Rapid Hexa chain. Regarding the measuring point, the front handle’s lower mean vibration magnitude was recorded with the Rapid Hexa chain; in contrast, the rear handle’s lower mean vibration magnitude was recorded with the Rapid Super chain.

3.2. Cutting Efficiency Comparison

Figure 3 shows a statistically significant difference (p ≤ 0.05) in cutting efficiency expressed as energy (E) and time (T) over area (A) between the two observed chains.

Cuts performed using the Rapid Super chain were more efficient regarding energy and time consumed per sawn area. This is not in line with the advertised statements about Rapid Hexa chain. Since the Rapid Hexa has narrower kerf in comparison to the Rapid Super, it is logical to assume more efficient sawing and less energy expenditure under the same conditions of testing. However, wood heterogeneity is always an unpredictable variable when performing sawing tests, a fact that could have influenced the obtained results. It should also be noted that although the samples were taken from the same fresh-fallen log, the mean area sawn with the Rapid Hexa chain was approximately 11% bigger than that with the Rapid Super chain. This fact could have partially caused the 37% increase in mean sawing time, as well as the 23% increase in energy consumption when using the Rapid Hexa chain. The increase in energy consumption is definitely influenced by sawing time since energy is a product of power and time. However, different results occurred when conducting the regression analysis (p ≤ 0.05) to predict the spent energy and time using the sawn area. Samples taken with the Rapid Super chain were tested and the results show that there is a linear relationship between spent energy and sawn area (R = 0.38; R² = 0.14; p = 0.04), but the test revealed that there is no linear relationship between spent time and sawn area (R = 0.26; R² = 0.07; p = 0.17). On the other hand, the test of the samples taken with the Rapid Hexa show that there is no linear relationship between spent energy and sawn area (R = 0.36; R² = 0.13; p = 0.51), but there is a linear relationship between spent time and sawn area (R = 0.45; R² = 0.20; p = 0.01). The obtained coefficients of determination show that, “in the best case”, the sawn area explains 20% of the variance in spent time and 14% of the variance in spent energy. This indicates that there are a great deal of variables not included in this study that influence the efficiency indicators.

Furthermore, one study [14] states that optimal efficiency occurs at 60 N of feed force, which is just about the weight of the average chainsaw. However, this could not be achieved in this measurement because the battery was inserted in the charger housing rather than in the chainsaw, due to energy consumption measurements. This made the chainsaw lighter, and, consequently, the feed force lower. A Polish study [30], however, also states that sawing time is directly proportionate to the applied feed force, and inversely proportionate to the rotational speed of the chainsaw engine. However, the feed forces in that study ranged from 51 to 118 N.

3.3. Vibration Magnitude Comparison

Figure 4 shows a statistically significant difference (p ≤ 0.05) between the two observed chains in the vibration total value on the front handle, whereas there is no statistically significant difference (p ≤ 0.05) for the values on the rear handle.

The vibration magnitude on the front handle is significantly lower when using the Rapid Hexa chain than when using the Rapid Super chain. This result is in line with manufacturers’ advertising since the measuring point is not specified. However, vibration magnitude is influenced by a number of factors [23], and to firmly state statistically significant differences, further measurements in controlled environment should be taken. Even so, the results imply that a simple saw chain replacement can significantly reduce the vibration magnitude and consequently lower the daily vibration exposure in a professional work environment. This is potentially a quick and simple solution to revise the time-based restrictions on chainsaw usage in some legislations and recommendations. However, it should be noted that exposure time is a significant factor in daily vibration exposure, and it is surely influenced by increased sawing time when using the Rapid Hexa chain.

4. Conclusions

Considering the obtained results in this study, it can be concluded that cutter tooth geometry and shape do influence cutting efficiency in terms of cutting speed (time) and energy consumption. However, it should be emphasized that the manual operation of the chainsaw does not allow for a reliable determination of differences in energy consumption caused by changes in saw chain geometry. It also influences the vibration magnitude. However, the efficiency results contradict the manufacturer’s advertising, while the vibration magnitude results are somewhat in line with the stated features of the Rapid Hexa chain. The more prominent features of Rapid Hexa are its ease of maintenance (sharpening) and production of less wood chips and dust due to the narrow kerf design. To bolster the statements about cutting efficiency and vibration, a fully controlled experimental plan should be adopted and implemented in future studies. Based on the results of this study, it can be concluded that the Rapid Hexa chain is not appropriate for professional use since it drastically increases the sawing time, despite a potential increase in operator comfort, i.e., lower vibration. However, hobbyists can benefit from its easier and straightforward chain maintenance.