Having at your disposal a screw lathe (hereinafter referred to as TVS), you can perform smooth or shaped turning of the workpiece; drill or bore a straight or tapered hole; grind the ends and cut the threads. It is possible to process parts with acceptable accuracy even on inexpensive models. It is not necessary to have a full-fledged specialized education to work independently on such equipment. Your own practical experience is of paramount importance. Of course, theory is important, but here it’s even simpler - you can study the structure of the machine and become familiar with the main features of its operation without leaving home.
The complete cycle of the author of the following video replaces the traditional course of theoretical training. Here is one of his videos:
Please note that the term “universal”, which appears in the technical documentation of fuel assemblies, refers to work with metals and plastics. Wood cannot be sharpened on a metalworking machine under any circumstances. There is specialized equipment for such tasks. The mechanisms of which are not afraid of wood dust, which is destructive for lubricants used in metal processing.
My article will help you understand the distinctive features of fuel assembly models and make an informed choice, taking into account certain needs and capabilities.
I'll start by presenting the most important characteristics that you should pay attention to. I present them in the table: Table of main selection criteria
| Criterion | Options | Description |
| Maximum diameter of the workpiece to be processed above the bed, mm | 100 – 500 | The specified range is valid for standard machines. Once upon a time, GOST regulated the production and certification of equipment for processing workpieces with a diameter of up to 6300 mm, today this is not the limit. This value indicates the permissible diameter of the part rotating on the axis of the spindle and tailstock |
| Maximum distance between centers, mm | 300 – 2032 | Characterizes the maximum length of the processed part of the workpiece |
| Spindle speed, rpm | 0 – 3000 | By changing this value within the tolerance for a specific workpiece (taking into account the structural characteristics of the material, dimensions and degree of processing), you can obtain the required result with minimal working time. With increasing spindle speed, the accuracy of the machined surface increases |
| Spindle through hole diameter, mm | 20 – 80 | The through hole of the headstock spindle allows you to process workpieces whose length exceeds the actual distance between centers. Determines the maximum permissible diameter of the length of length being turned |
| power, kWt | Up to 1 | Amateur "hobby" equipment. For small volumes, minimal loads are assumed |
| From 1.5 to 6 | Machines for small business organizations, repair and creative workshops | |
| Over 7 | It is advisable to install it in experimental and production workshops at large enterprises. | |
| AC supply network, V | Single phase (220-240) | Amateur machines |
| Three-phase (380-400) | Professional machines | |
| Weight, tons | ||
| Lungs – up to 0.5 | Allows you to work with workpieces with a diameter of 100 – 200 mm | |
| Medium – up to 4 | A number of the largest workpiece diameters are in the range of 250 – 500 mm | |
| Large – up to 15 | Can process parts 630 – 1250 mm in diameter | |
| Heavy – up to 400 | Copes with the largest options from a range of largest diameters |
As for the weight of the machine. There is a dependence of the weight of the unit on its “professionalism”. There is a conditional relationship between the weight of the machine and the maximum diameter of the workpiece being processed.
Please note: factors that directly indicate the purpose of the equipment are deliberately placed in the last places of the table. Look for fuel assemblies based on the actual level of the tasks at hand - hobby, small business or industrial enterprise. This way you can choose the most functional and cost-effective machine model.
Home equipment
Machining parts on fuel assemblies for amateur needs is impossible when you have 1-2 cutters at your disposal. Creative work will take an unpredictably long time if you have to look for belts, gears or shafts on your own. Maintainability and configuration are the main points that deserve the attention of the user of entry-level turning equipment.
Caliber STMN-550/350 – from 41,000 rubles.
A lightweight and compact entry-level machine allows you to perform the entire range of work on “adult” models. Assembly and adjustment in accordance with the instructions guarantees accuracy of operation. Preliminary preparation of the workpiece, removal of chips of no more than 0.2 mm in one pass, maintenance every 50 hours of operation has a positive effect on the condition of the equipment. To the point that the working life can exceed the 3 years declared by the manufacturer. A personal “crash test” with an increase in load beyond the recommended one led to the engine shutting down. Thus, the electronic protection system prevents excessive wear of plastic gears and burnout of the electric motor windings. Characteristics of STMN-550/350
| Characteristic | Meaning |
| Permissible diameter of the workpiece above the bed, mm | 180 |
| Distance between centers, mm | 350 |
| Spindle through hole diameter, mm | 20 |
| Speed, rpm | 0 — 2500 |
| Weight, kg | 40 |
| Features of the basic configuration |
|
| Homeland of the brand/country of manufacture | Russia/China |
In the following video, the author talks about his impressions of working on this machine. He also shared about his small modifications that he made while owning the unit:
Kraton MML-01 – from RUB 52,169.
Another variation of a fascinating construction set on the theme of Russian-Chinese fuel assemblies.
The machine became famous due to its collection of cutters, a set of gears for adjusting the automatic feed of the caliper and its maintainability. As the equipment is assembled, it is necessary to remove the preservative composition from the parts. Follow the recommended lubrication intervals and periodically check the position of drive parts. Before the first start under load, it makes sense to disassemble the headstock housing and securely tighten the screw securing the fork, which changes the position of the input shaft gears. This simple operation will protect you from serious consequences caused by small things getting loose and falling into the vents of a working mechanism. The problem with this fuel assembly is the plastic gears, which break due to careless use. The problem is solved by replacing them with cast iron ones. Characteristics of KRATON MML-01
| Characteristic | Meaning |
| Permissible diameter of the workpiece above the bed, mm | 180 |
| Distance between centers, mm | 300 |
| Spindle through hole diameter, mm | 16 |
| Speed, rpm | 50 — 2500 |
| Weight, kg | 38 |
| Features of the basic configuration |
|
| Development/production | Russia/China |
Here is a video - a review from the owner of this device after a month of use. The author shared useful minor improvements:
Corvette 402 – from RUB 77,529.
Despite some similarity in tactical and technical characteristics, the Voronezh Enkor stands out from other light fuel assemblies produced in China. This is honestly communicated to the user on the first page of the instructions. Among other differences, I will note the extended base and high-quality components. Due to this, the recommended chip removal depth is 0.2 mm, maximum 0.3 mm. Not a single machine among its closest analogues has such an opportunity. The increased dimensions of the working area and a real 0.75 kW single-phase motor fully cover the needs of the home craftsman. The greater weight reduces vibration and increases the stability of the table saw. Characteristics of the Corvette 402
| Characteristic | Meaning |
| Permissible diameter of the workpiece above the bed, mm | 220 |
| Distance between centers, mm | 500 |
| Spindle through hole diameter, mm | 20 |
| Speed, rpm | 100, 250, 350, 500, 900, 1800 |
| Weight, kg | 105 |
| Features of the basic configuration |
|
| Development/production | Russia/China |
Here is a review of this machine. The performance characteristics of the unit are given and its functionality is demonstrated:
Small Business Equipment
The selection of fuel assemblies for a production or repair business project is always carried out taking into account the inevitable modernization for similar tasks. There are no problems with processing precision for equipment in this category. Wear resistance is also at the level. But some manufacturers rely on the universal potential, others on the dimensions of the machine’s working area. Identify your main tasks and look for a machine to implement them. Then the purchase of a new fuel assembly will not affect the profitability of the business.
Proma SKF-800 – from RUB 272,365.
The combination of milling and screw-cutting devices within one lathe turned out to be one of the best solutions of the Czech Proma SKF-800.
The rotary drilling unit and the impressive diameter of the hole in the spindle allow you to work with fairly large parts. 2 identical three-phase motors guarantee sufficient torque for each device. A worthy option for those who plan to engage in professional activities in a small workshop. The only design flaw is the lack of tight contact of the protective panels with the frame. Because of this, chips and lubricants can cause rapid wear of the drive mechanisms. The manufacturer recommends that exposed parts be thoroughly cleaned and lubricated twice a day. I recommend checking the belt tension during each maintenance break. Characteristics of Proma SKF-800
| Characteristic | Meaning |
| Permissible diameter of the workpiece above the bed, mm | 420 |
| Distance between centers, mm | 750 |
| Spindle through hole diameter, mm | 28 |
| Speed, rpm | 160 -1360 (7 steps) |
| Weight, kg | 230 |
| Features of the basic configuration |
|
| Homeland of the brand and country of origin | Czech |
Video from the manufacturer Proma, the video shows the performance characteristics and reveals the functionality of the machine:
MetalMaster X32100 – from RUB 284,970.
Thread indicator, digital display device, longitudinal and transverse automatic feed system; supply of lubricant and cooling fluid - a machine from MetalMaster simplifies the process of metal processing without loss of quality. Professionals often compare the functionality of this machine with Soviet equipment of a similar profile. I consider such analogies to be incorrect - apart from a certain set of functions, nothing connects them.
- X32100 removes 3 mm chips in one pass
- Discretion of carriage stroke in any direction – 0.001 mm
- MetalMaster provides the opportunity to reduce equipment costs by 12% by eliminating the digital display device (12% of the cost).
With such a ratio of potential, compact dimensions, ergonomic controls and 1 year of official warranty, this machine has no competitors in the price segment up to 300,000.
Characteristics of MetalMaster X32100
| Characteristic | Meaning |
| Permissible diameter of the workpiece above the bed, mm | 330 |
| Distance between centers, mm | 1000 |
| Spindle through hole diameter, mm | 38 |
| Speed, rpm | 65 - 1810 (18 speeds) |
| Weight, kg | 520 |
| Features of the basic configuration |
|
| Development/production | Russia/countries of Southeast Asia (SEA) |
The video shows the machine in operation - the thread cutting process on this unit is demonstrated. In principle, everything is done easily, and special training is not needed at all to work on this machine:
Jet GHB-1330A – from RUB 350,000.
The scope of use of this fuel assembly is small-scale production and piece products.
Weight, length of the frame and a small basic set of accessories indicate the professional orientation of the equipment. That is, when the necessary equipment is purchased as needed to perform specific tasks. Having experience working on this machine, I can say that in addition to convenient control and actual power, the length of the bed or the width of the through hole of the spindle is definitely not enough. Changes had to be made to the order for meter-long spatial structure elements made from a 50-millimeter pipe at the discussion stage. If the specifics of the work are not related to the maintenance of construction sites, then this machine will be a justified investment in the development of your business. Characteristics of JET GHB-1330A
| Characteristic | Meaning |
| Permissible diameter of the workpiece above the bed, mm | 330 |
| Distance between centers, mm | 760 |
| spindle through hole diameter, mm | 38 |
| Speed, rpm | 70 - 2000 (8 speeds) |
| Weight, kg | 600 |
| Features of the basic configuration |
|
| Development/production | Switzerland/SEA, Europe |
Detailed video review of the model. The author provides the performance characteristics of the machine, its functionality, and demonstrates it in operation:
General information about screw-cutting lathes
Almost all machines identified in this group have the same structure and operating principle. They perform milling operations on workpieces made of ferrous and non-ferrous metals (including cast iron) and plastics. Specific technological capabilities are determined by the layout and accuracy class of the equipment, design features (modifications of machines), and the presence or absence of a numerical control (CNC) system.
Despite various modifications and different equipment manufacturers in Russia and abroad, the operating principle of such machines remains practically unchanged. The fixed part rotates around the longitudinal axis, a cutting tool is brought to it, with which part of the material is removed and the surface is formed. The main difference from conventional lathes is that on this equipment it is possible to cut threads along the outer diameter of workpieces.
Industrial equipment
From among the standard fuel assemblies of the industrial group, you can select an option for both the workshop and the experimental workshop. The discreteness of the stroke and the permissible error are regulated by standards. The operation of components and mechanisms is ideal with the established maintenance procedure. The difficulty of choice lies in a thorough comparison of the capabilities of a standard machine and the expected operating features. Minor modifications are allowed. If there are obvious non-conformities, upgrading must be carried out by the manufacturer. Optimally – fuel assemblies made to order.
Stalex GH-1430B – from RUB 540,611.
The oil bath of the gearbox, from which the headstock bearings are lubricated, and the rigidity of the structure bring the domestically developed product as close as possible to the high standard of older FA models.
The advantage of the younger machine is the error declared by the manufacturer of 0.005 mm. Considering the features of service and the stated cost, I can confidently say that equipment with such precision should be classified as industrial. Which, despite its average dimensions, will be effectively used only in the conditions of a production and experimental workshop. Characteristics of Stalex GH-1430B
| Characteristic | Meaning |
| Permissible diameter of the workpiece above the bed, mm | 330 |
| Distance between centers, mm | 750 |
| Spindle through hole diameter, mm | 38 |
| Speed, rpm | 70 — 2000 |
| Weight, kg | 510 |
| Features of the basic configuration |
|
| Homeland of the brand | Russia |
Proma SPF-2000PH – from RUB 1,220,000.
For drilling, reaming holes, grinding parts and rolling corrugations on the scale of repair and locksmith shops of large enterprises, accurate and powerful machines are required. The Czech version with a 2-meter working surface of the bed, a 5.5 kilowatt electric motor and a hydraulic station for supplying lubricating and cooling fluid meets all the requirements for industrial equipment. 2 steady rests on the bed increase the efficiency of processing large-sized workpieces. Maintenance of Proma SPF-2000PH requires certain qualifications from personnel. Therefore, at enterprises, the replacement of process fluids and local repairs are entrusted to highly specialized specialists. I recommend entrusting the first commissioning work to specialists from the manufacturer. Characteristics of Proma SPF-2000PH
| Characteristic | Meaning |
| Permissible diameter of the workpiece above the bed, mm | 460 |
| Distance between centers, mm | 2000 |
| Spindle through hole diameter, mm | 80 |
| Speed, rpm | 25 - 1800 (12 speeds) |
| Weight, kg | 3055 |
| Features of the basic configuration |
|
| Development/production | Czech |
Jet GH-2040 ZH DRO RFS – from RUB 1,165,000.
The index “2040” in the TVS marking identifies the junior model of the senior line of standard lathes of the GH ZH DRO RFS series, from the international corporation JET.
The differences between each of the 4 options are in the dimensions of the equipment and the maximum length of the workpiece. The motor is 12 kW, the parameters of each of the 4 possible thread options, the rotation speed of the feed shaft for the GH ZH DRO RFS models are completely identical. Which allows us to conclude about the impressive potential of fuel assemblies with code 2040. Characteristics of JET GH-2040 ZH DRO RFS
| Characteristic | Meaning |
| Permissible diameter of the workpiece above the bed, mm | 500 |
| Distance between centers, mm | 1015 |
| Spindle through hole diameter, mm | 80 |
| Speed, rpm | 9 – 1600 (24 positions) |
| Weight, kg | 2750 |
| Features of the basic configuration |
|
| Development/production | Switzerland/SEA, Europe |
A detailed review of the model - issues from configuration to the hardness of the frame are considered; Maximum cut per revolution tested:
Design features
A special feature is the presence of a variator. It allows you to change the spindle speed. The rotation of the main engine through a V-belt system and a gear coupling transmits the rotation of the spindle to the variator input shaft. The change in speed occurs due to a change in the distance between the conical disks.
By reducing the gap, the discs push the V-belt to the edge and the diameter of the pulley increases. The gear ratio increases - the spindle speed increases. The same design is used on the variator output shaft.
Placing the variator on the frame without connection with the stand and installing the apron on an independent suspension reduces the vibration level. The use of precision bearings and the rigidity of the machine structure ensure precise processing of parts.
The feed box allows you to cut threads in the range of:
- metric (in mm) from 0.2 to 28;
- modular (in mod) from 0.1 to 14;
- inch (threads per inch) from 5 to 96.
Changing the speed of longitudinal and transverse feeds without changing the gears in the guitar.
Dimensions and weight
Overall size: 0.725m x 1.36m x 1.51m.
Weight in kg – 765.
Location of components
- The cabinet contains inside a lubrication mechanism, a main drive, a variator, and a box with electrical equipment. The cabinet is mounted on a frame with a level adjustment mechanism.
- The bed is fixed in the upper part of the cabinet. It houses the headstock, tailstock and apron.
- The headstock includes the spindle assembly, guitar and feed box.
- The apron is equipped with a support with a tool holder, a mechanism for longitudinal and transverse feeds, and a protective shield.
- The tailstock moves along the frame guides and is secured with bolts.
Control structure
The controls are located on the front of the machine and are grouped where the mechanisms they control are located.
The variator is controlled:
- The variator speed shift knob (switches the spindle speed ranges).
- The flywheel changes the spindle speed (the spindle speed is smoothly controlled by moving the sliding disk of the planetary gear).
- Spindle rotation control handle (switches the direction of spindle rotation).
On the front side of the headstock casing there are switches for controlling speed selection, a link for increasing the thread pitch, reversing the feed drive, switching feeds, turning on the lead screw and roller, and switching feeds.
These elements control the gearbox and the engagement of gears on the lead shaft or lead screw. Control occurs by selecting the required combinations of gear engagement and gear couplings of the gearbox.
Kinematic diagram
The electrical circuit consists of two asynchronous motors powered by a 380 V industrial AC network. It is possible to power a step-down transformer from a 220 V network.
Provides 12 V to power the lighting lamp and 110 V to power the circuit controls. These switch buttons, starters and overcurrent protection elements (thermal relays). Electrical equipment is the main weak point of the machine. Requires constant monitoring.
Electrical diagram
Variable speed drive
The variator consists of a two-stage gearbox and the variator itself. The main motor rotates the drive shaft through a gear coupling. There are two conical disks on the shaft. One is rigidly fixed, and the other is spring-loaded and can move along the axis.
These two discs form the drive pulley of the variator. The drive pulley uses a V-belt to rotate another pair of identical disks, forming the driven pulley. They are located on the driven shaft. It transmits rotation to the gears of the range switching box.
Headstock
The front (spindle headstock) is rigidly fixed to a massive frame. The spindle head housing contains:
- spindle - rotates in precision rolling bearings;
- overkill - a set of gears that allows you to expand the range of thread pitch by changing the gear ratio;
- lead screw drive with bit (controls change in feed direction);
- control mechanism;
- mechanism for supplying lubrication to bearings and gears.
Gearbox
The feed box and guitar change the gear ratio to cut threads with different pitches and obtain longitudinal and transverse feeds.
Caliper
The cross-type machine support consists of:
- lower slide – moves longitudinally along the frame guides;
- cross slide – moves in the transverse direction;
- rotary slide – fixed on the cross slide and set to the required angle according to the scale marked on the cross slide. Used for making cones;
- tool holder – rotatable to 4 positions with locking.
Apron
Designed to provide longitudinal and transverse feed of the caliper. Equipped with a mechanism for blocking the simultaneous activation of the lead screw and the lead shaft.
My choice
No matter how detailed the advantages of screw-cutting lathes are described, it is difficult to draw an unambiguous conclusion regarding industrial equipment. Each production has its own characteristics, due to which special machines are ordered and standard machines are modified. From the standpoint of standard equipment, the JET GH-2040 ZH DRO RFS , due to its existing potential, stands out against the background of a small number of worthy competitors.
The most numerous in terms of the range of characteristics is the group of machines that is of interest to small businesses. Here you can always choose models that suit your characteristics. The easiest way is with MetalMaster X32100 - already in the basic configuration you get an accurate and high-performance fuel assembly, there is no need to modernize the machine.
It is more difficult to define a machine for a hobby - the proliferation of similar models affects it. Against which the KRATON MML-01 : a set of cutters, a set of gears and shafts, all the necessary tools. The affordability and maintainability of the machine predetermined its popularity. Minimal modifications can correct small structural defects.
How often do you service your power tools?
I hope that the article was useful to you. Thank you for your attention, ask questions, share your experience in the comments.
Turning a large diameter workpiece on a CJK61160 machine
Turning the workpiece of the distribution chamber bottom
Product Specifications
| Diameter, mm | 1320 |
| Thickness, mm | 40 |
| Weight, kg | 425 |
When trimming, the cutting speed changes in proportion to the change in diameter, provided that the rotation speed of the part is constant. To obtain a high-quality surface, it is necessary to ensure a constant cutting speed; for this, the revolutions change, and when the processing diameter decreases (the cutter moves towards the center of the part), the revolutions must increase. This follows from the calculation of the cutting speed at a given speed: V=π*D*n/1000. This is achieved by a program code (G96), by which the machine smoothly increases speed as the cutter moves towards the center of the part, this is clearly visible in the video. It is impossible to ensure the specified speed at the center itself due to the size and weight of the cartridge and the part, so the surface turns out to be “matte”. For critical parts, processing modes are assigned and controlled by a technologist.
| Installing the workpiece into the chuck | Centering the workpiece |
| Operator's work | Operator's work |
| Turning Process | Turning Process |
| Grooving | Grooving |
| Processed workpiece | Removing the workpiece |
Load drum turning
Product Specifications
| Diameter, mm | 913 |
| Length, mm | 3000 |
| Load drum turning | Load drum turning |
Ready product
