Design of Small Multi Purpose Power Weeder


design project

Design of
Small Multi Purpose
Power Weeder

AEA 977051




In Indonesia, as well as in some other Asian Countries, there are regions those by their geographical, morphological or socio-economical conditions, adoption of large or medium power weeder is impossible.

In hilly regions land surfaces are high sloped and farmers cultivate those lands by making terraces. The land is divided into small fields. Higher the slope results in smaller fields. This condition is more compulsory in growing rice because lowland traditional practice needs a level surface for flooding.

In other areas land owning is very small in size because of the high population that one farmer can not have larger piece of land. Even if the land surface is level, to make these small fields to become a larger one is practically impossible.

Need of weeding performance improvement in such areas calls for types of weeder those are small in size, easy to use, cheap, and can cope the flexibility and nobility problem encountered.

Multi purpose small power weeder is coming to answer that specific demand.


2.1. Weed Control Practices

Weeding control is done by: mechanical weeding, thermal weeding: flaming, biological control, chemical control, and by farming pattern.

a. Mechanical Weeding

Mechanical weeding is defined as applying mechanical force for weeding operation. The operation can be divided into

  1. Hand weeding by using hand / finger to pull out (uproot) weed from the ground. This is practiced especially on wetland paddy field.
  2. Using small hand operated weeder welknown as hand weeder or push weeder although actually to operate it operator pushes and pulls it on the ground surface.

There are some kinds of hand weeder:

a) skid type or boat type weeder, consist of a plate made from steel sheet or wooden, with weeder finger or claw attached on the bottom side of it.
b) rotary weeder, consist of one or two rotary weeding component.

There are some subtypes of rotary weeder: single rotor, double rotor, and cono weeder. The weeding tines vary from spike / nail type to plate / flange type.

3) Power weeder, engine operated. There are large and small power weeder, some are self propelled. others are tractor implement.

b. Thermal Weeding

Thermal weeding is a weeding control by using high temperature. It is held by applying flame to kill weed. Some flaming machine now available consist of fuel tank, hosing and pipes, beam, and flame nozzle. Flame is applied closely to the ground surface. Crop shield is provided to prevent plant from damage by the flame.

c. Chemical Weed Control

Chemical weed control is a weed control using chemical (herbicides). It is now extensively and intensively used. Some advantages of chemical weed control are the low labour consumption, easy to apply, can be applied on broadcasted crop, and highly effectiveness in killing weed. But environmental consideration must be taken because of its poisonous nature brings serious pollution and damage to the nature and to the life of human being as well as the life of all plants and animals.

d. Biological Weed Control

Biological weed control is a kind of controlling weed by taking advantages from biological agents those are natural enemies of some kinds of weeds.

e. Weed Control By Crop Management

Some kinds of crop rotation can effectively suppress the population or regeneration of weed as well as pests. For example, alternating pattern lowland – upland practiced in some countries in some extents is able to control weed, because some water weeds die at dry condition and some dry weeds can not live on flooded field.

2.2. Mechanical Weeding Process

Mechanical weeding done by: cutting weed stack above ground surface, uproot weed by pulling it from the ground, pulverize the soil and chop the weed, or by invert the top layer of the soil thus cover the weed with soil. In paddy field one other method can be applied, i.e. puddling the soil and sink the weeds into the puddled soil.


3.1. Field Parameters

a. Upland and Lowland Farming System

Weeding operation highly depends on the farming pattern or planting methods. Technology for upland and lowland farming system is different because of some differences between one and another. Some important characteristics differences between upland and lowland are:

  1. Soil strength. Soil strength in wetland farming is much lower compared with of dryland farming
  2. Tillage operation
  3. Planting system
  4. Methods of controlling weed

b. Size of fields

There are very large, large, medium, small, and very small field categories. A certain type of machine may suitable for a certain size of field but nay be not appropriate for other sizes. large machinery seem more appropriate and suitable used in large field while small machines seem more suitable for small field size. Using large machinery on small filed results in mobility problem and large amount of wasted times that in turn results in very low field operation efficiency.

c. Geographical condition

Large farm machinery is have special problem when it must be used at hilly regions. High slope make operation with large machinery become dangerous. In some other regions using some large machines even practically impossible.

d. Social economic of farmers

Small farmers with their lack of capital are not able to afford expensive machines. Cheaper ones are more appropriate for them.

e. Crop

Some kinds of crops may need specific means of weeding control.

3.2. Design Specification Requirement

The purpose of this design project is to design a machine which has characteristics as follow:

The machine can overcome the mobility problem in sloped / hilly region, and mobility problem in soft paddy field, has flexibility on various filed size and filed shape irregularities, the cost is reasonable, the weeding effectiveness, field capacity and filed operation efficiency are reasonable, and has versatility for using on various crops.

Hand weeding has highest effectiveness on the paddy field, but it is not appropriate for upland farming.

Hand weeder .is used extensively in paddy field but it has little use in upland.

Many tractor operated power weeder are not useful at all at hilly region, and furthermore, they are expensive.

For satisfying the specific demand the machine must not so large. Light machine which can be mounted on human body is having good suitability.

There is a kind of machine for grass management usually used for maintenance of gardens and parks i.e. hand mower. The engine of the machine is light enough to be mounted on human body. The working component consist of two blades attached at the end of long shaft covered by a steel pipe which acts as the handle.

There are two kinds of hand mower: with flexible shaft and without flexible shaft.

Hand mower seems to be a good machine, if properly modified, to be used as weeder machine on such regions previously mentioned . It has some advantages i.e.: Not so much expensive, versatile for various crops, eliminates the mobility problem in sloped region, in small field, and in paddy field as compared with large machinery, and improving capacity compared with hand weeder.


4.1. General

Basically hand mower consists of 4 parts: power source (engine), transmission shaft, handle, and cutting blades

a. Engine

The engine for hand mower is a very light engine, with power rating 0.9 kW, engine weight 5 kg, volume displacement 25.4 cc.

b. Transmission shaft

There are two types of transmission shaft: with flexible shaft and with extension shaft fixed to the engine.

c. Handle

There are two principle types of handle: bicycle steering and curved handle as like the shape of hand tractor handle. The handle is fixed to the shaft covering.

d. Cutting blades

Cutting blades are attached at the end of the shaft. The cutting action takes place by the rotation of the blades. The gigh speed rotation results in impact and shear force to cut the grass body just about the ground surface.

4.2. Modification

To make the mower / trimmer suitable for weeding operation between plant rows, some modification must be done.

a. Shape and dimension of blades

Because the original use of the machine is for cutting lawn grass, not to cut weed between plant rows, the original dimension of the blades is too long so that if it not be modified it will damage the crop asa well as the weed when be used on a weeding operation. Then the dimension of the cutting blades must be reduced.

b. Addition of plant shield

For the plant safety reason, plant shield must be added to cover the rotating blades so if the working component of the machine is in contact with plant body, it is the shiled not the rotating blades which is in contact with the plant body, so it will prevent plant damage.


5.1 Dimensions

For dimension consideration, paddy row spacing at about 25 cm is used as the standard spacing. For the case of a machine working part moving between plant rows, the overall diameter of the rotating blades is set 15 cm. With 1 cm clerance between rotating periphery and shiled line, the overall diameter of the working part is 15 + 1 + 1 = 17 cm.

The blades are bolted to the blade base. The base diameter = 6 cm. The blade effective length = (15 – 6) / 2 = 45 cm. The overlapping part between blade and the base = 2 cm. Total blade length = 4.5 + 2 = 6.5 cm. Blade with is set 2.5 cm.

5.3. Material

Material for blades is medium carbon steel, with thickness 5 mm. Material for shield is shhet steel 1 mm.


6.1 Making Prototype

After the design process is completely finished and the idea has been properly put out on the form of engineering drawings, then prototype of the machine can be made using all the informations provided in the design specification. Prototype is made using dimensions and materials described in the design specification.

6.2. Preliminary Test

Preliminary testis a very important stage of a design process, because there are often some variables not accounted for previously although the designer has tried to do at his best. In the perliminary test then can be found out whether the idea of the design can work on real situation or not. If it could work, sometimes there are still some modifications needed to be done.

6.3. Design Modification

From the preliminary test the found defects of the design then to be modified to improve the performance or to eliminated the defects.

6.4. Field Testing and Evaluation

When some kind of machine pass prliminary test and has already been modified, then the time is coming for filed testing. During and after the field test the machine is evaluated for its overall field performances.

6.5. Refinements

Some machines may need some refinements to improve its performance characteristics.

6.6. Manufacturing

If the machine can pass feasibility considerations that involve economical and financial as well as technical considerations, then it can be produced using appropriate manufacturing process.

Perihal Pak Tas

7 Responses to Design of Small Multi Purpose Power Weeder

  1. suprih mengatakan:

    I love read your post, and you have nice blog, I will back here again:)

  2. gangadhar r. phadke mengatakan:

    I am the student of in Agriculture Engg. in the department of Farm power and machinery in Dr. Punjabrao Deshmukh Krishi Vidyapeeth Akola (M.S) India. I am working on the project title ” Development of rotary power weeder.” so i want the information about design consideration for row crop weeding.(30cm, 45cm, 90cm distance.)
    Thanking you.

  3. Aliyu Idris mengatakan:

    l am student of Bayero University, Kano Nigeria. I am doing my project on Development and performance evaluation of cono weeder. Please l need the design equations for such weeder. My email is I am looking forward to hear from you soonest. Thankyou.

  4. mengatakan:

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  7. Joko Pitoyo mengatakan:

    Hallo mr. Tasliman i am very apreciated to your paper. Actually I knew you very well since your are in UGM and also when you studied at IAT. I had also done some activities cover large area about research and develop power weeeder for paddy field since 2000. Now I am at Kobe university Japan for doing Phd, my research also related study about efficacy and efficiency of portable power weeder. I would like to ask you to share your paper which you have been done in several years. thank you

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