Over the hundreds of years that people have been processing wood and making various products from it, it seems that the craftsmen have tried all possible tools and devices. Meanwhile, the creation of all kinds of devices continues to this day. It is likely that all this was already invented by someone in past years, but each master tries to make devices that are suitable for him.
Wooden picture or photo frames are compressed when glued together, probably in hundreds of different ways. I myself can offhand offer at least a dozen options; here is one of the devices for this work from White Myers, Workbench website.
Tape ties are most often used for compression when gluing square or rectangular products. Such as chairs, stools, boxes and small tables. The use of this mechanism is convenient because you can compress the entire product at once by applying glue and assembling the legs, drawers and legs of the chair. But when gluing wooden frames, a tape tie in its usual form is not suitable. The fact is that during compression it is impossible to maintain angles exactly 90*, due to uneven contraction.
In order to use a tape tie when assembling the frames, you need to make four corner blocks. The blocks have an external rounded edge, which helps to compress the product evenly, and a sawn internal corner, exactly at 90*. It is imperative to drill a hole at the starting point of the corner to prevent the frame from sticking to the blocks. More options for frame clamps in the article.
Small parts clamp
Every craftsman who works with wood uses sanding discs and sanding drums to process parts. Sometimes you have to process a large number of small wooden parts. It can be difficult to hold them in your hand, and there is a risk of catching the drum with your hands.
To make the clamp you will need two wooden blocks 150-200 mm long. and cross section 30/15 mm. . The bars can be made by sawing a round piece with a diameter of 30 mm into two parts. . Holes are drilled in the center of the bars for a clamping bolt with a wing and several washers.
During operation, the required gap between the platforms is immediately established, and compression is carried out using a wooden wedge in the tail section. The process is quick and simple: insert the part, push in the wedge and work. We take out the wedge, change the part and again clamp it with the wedge.
It is very important that during processing the part is correctly and permanently fixed. That is why tools are often required that will be assistants in such situations and will be able to solve this problem in such a way that during any thermal or mechanical treatment it remains in one motionless position, as the master needs.
By the way, an angular clamp is just such a clamp that is perfect both for fixing a part during processing and for compressing several parts into a single whole so that a strong bond is obtained.
The principle of operation of the clamp
If the master decides to do some work from wood or metal, then he should process the part. But this can be done efficiently only if this part is fixed very firmly with a clamp.
Old models of such a tool allowed working with only one hand, but now new models of this tool are appearing, which serve as an integral assistant to any master, and they are not only quick-clamping, but also allow you to work with the part with two hands.
There are several types of such clamps:
- Lever.
- Screw.
- Assembly.
- Corner.
- Manual.
Let us briefly describe each type of clamp. The first type is lever. This means that the work of such an assistant tool is based not only on axial work, but also on the work of levers. Often people also call them clamps, which allow you to quickly fix parts intended for processing.
Lever clamps do not require much force from the master; in order to clamp something with them, you just need to apply a little force. And so that the parts are clamped tightly and can no longer move, it is necessary to use a lever, which will do all the work for a person.
The design of such a lever clamp is quite simple; you can even make it yourself. To do this, you will need a main frame and some element where the main clamp can be located. With the help of such an assistant tool, you can not only clamp parts and make them motionless, but also calculate the clamping force, which is important, for example, when gluing.
The remaining types of clamps differ from the first type and from each other in that they have different clamping mechanism. Many of these types of assistant tools can be made with your own hands.
How to choose the right clamp when purchasing
Choosing a tool such as a clamp is not difficult, you just need to know a few rules that will help you purchase such a tool - an assistant that will become indispensable for you when performing any type of work. First of all, you should pay attention to what the working stroke of your tool is.
In addition, it is worth paying attention to the fact that what is the distance between the elements - clamps. The higher the scores on these two points, the better this tool will be for you. This will allow you to use clamps for working with parts, both large and small.
Types of screw clamps
In such an assistant tool, the first place is no longer a lever, but a screw. This type of clamp is also popularly called a pipe clamp, since it is used for clamping pipes that are usually used for plumbing work.
Such a tool is considered very strong and reliable in the plumbing industry, as it is made of duralumin. By the way, such instruments are also used to make special holes for installation, so that it is convenient to fasten any part to the workbench when working. Making such a tool with your own hands and at home will be quite difficult.
Now a few words about the assembly clamp, which is most often used in the construction of various objects. The main purpose of such a tool is hold any construction materials, such as reinforced concrete slabs, so that they can be processed efficiently.
This clamp is considered the most reliable for work, but if you study its design, you can easily understand that it is simple. Looking at the drawing, which reflects its constituent elements, you can easily assemble it with your own hands.
The manual clamp has several options:
- Cam.
- Wedges.
- Angular.
There are other options for such a hand tool - an assistant. Popularly, such a clamp is called a spring clamp. This is due to its simple design and equally simple application. Therefore, you can easily make such an assistant tool with your own hands.
Instructions for making a tool - an assistant with your own hands
To make a clamp, you must correctly follow the step-by-step steps described in the instructions. First, we acquire the parts that are necessary to make a tool - an assistant with our own hands.
To make a clamp you will need the following items: n several studs with threads of different diameters, nuts, which are suitable in size, several boards made of plywood, and a couple of slats.
The second step for making a clamp is to create the base. You can also make it yourself. To do this, you should secure what you have already done on the table. Then we take the bars and, applying them to the clamp, drill holes where they are needed in order to press them more tightly to the base of the table.
The third step is to make the clamp yourself. This will require those plywood boards that you prepared in advance. You must press them against the bars that are already attached to the clamp, but so that they are movable.
You must understand that the role of these boards in the tool that you make with your own hands is to act as levers in the clamps. Now using studs and nuts, all that remains is to secure this entire structure that you made with your own hands.
But when using such a tool - an assistant that you made yourself, you should understand that it is not very durable and it is difficult to talk about its reliability. But it can be perfect for many household jobs, if they are not very complex.
The eccentric clamp is an improved design clamping element. Eccentric clamps (ECC) are used for direct clamping of workpieces and in complex clamping systems.
Manual screw clamps are simple in design, but have a significant drawback - to secure the part, the worker must perform a large number of rotational movements with a key, which requires additional time and effort and, as a result, reduces labor productivity.
The above considerations force, where possible, to replace manual screw clamps with quick-release clamps.
The most widespread are also.
Although it is fast-acting, it does not provide high clamping force on the part, so it is used only for relatively small cutting forces.
Advantages:
- simplicity and compactness of design;
- widespread use of standardized parts in the design;
- ease of setup;
- ability to self-braking;
- speed (drive response time is about 0.04 min).
Flaws:
- the concentrated nature of the forces, which does not allow the use of eccentric mechanisms for securing non-rigid workpieces;
- the clamping forces with round eccentric cams are unstable and significantly depend on the size of the workpieces;
- reduced reliability due to intensive wear of the eccentric cams.
Rice. 113. Eccentric clamp: a - the part is not clamped; b - position with clamped part
Eccentric Clamp Design
Round eccentric 1, which is a disk with a hole offset relative to its center, is shown in Fig. 113, a. The eccentric is freely mounted on axis 2 and can rotate around it. The distance e between the center C of disk 1 and the center O of the axis is called eccentricity.
A handle 3 is attached to the eccentric, by turning which the part is clamped at point A (Fig. 113, b). From this figure it can be seen that the eccentric works like a curved wedge (see shaded area). To prevent the eccentrics from moving away after clamping, they must be self-braking. The self-braking property of eccentrics is ensured by the correct choice of the ratio of the diameter D of the eccentric to its eccentricity e. The ratio D/e is called the eccentric characteristic.
With a friction coefficient f = 0.1 (friction angle 5°43"), the eccentric characteristic should be D/e ≥ 20, and with a friction coefficient f = 0.15 (friction angle 8°30") D/e ≥ 14.
Thus, all eccentric clamps, whose diameter D is 14 times greater than the eccentricity e, have the property of self-braking, i.e., they provide reliable clamping.
Figure 5.5 - Schemes for calculating eccentric cams: a – round, non-standard; b- made according to the Archimedes spiral.
Eccentric clamping mechanisms include eccentric cams, supports for them, trunnions, handles and other elements. There are three types of eccentric cams: round with a cylindrical working surface; curved, the working surfaces of which are outlined along an Archimedes spiral (less often - along an involute or logarithmic spiral); end
Round eccentrics
Due to ease of manufacture, round eccentrics are most widespread.
A round eccentric (in accordance with Figure 5.5a) is a disk or roller rotated around an axis displaced relative to the geometric axis of the eccentric by an amount A, called eccentricity.
Curvilinear eccentric cams (in accordance with Figure 5.5b) compared to round ones provide stable clamping force and a larger (up to 150°) rotation angle.
Cam materials
Eccentric cams are made of steel 20X, carburized to a depth of 0.8...1.2 mm and hardened to a hardness of HRCe 55-61.
Eccentric cams are distinguished by the following designs: round eccentric (GOST 9061-68), eccentric (GOST 12189-66), double eccentric (GOST 12190-66), eccentric forked (GOST 12191-66), eccentric double-bearing (GOST 12468-67) .
The practical use of eccentric mechanisms in various clamping devices is shown in Figure 5.7
Figure 5.7 - Types of eccentric clamping mechanisms
Calculation of eccentric clamps
The initial data for determining the geometric parameters of the eccentrics are: tolerance δ of the size of the workpiece from its mounting base to the place where the clamping force is applied; angle a of rotation of the eccentric from the zero (initial) position; required force FZ of clamping the part. The main design parameters of eccentrics are: eccentricity A; diameter dc and width b of the eccentric pin (axis); eccentric outer diameter D; width of the working part of the eccentric B.
Calculations of eccentric clamping mechanisms are performed in the following sequence:
Calculation of clamps with a standard eccentric round cam (GOST 9061-68)
1. Determine the move hTo eccentric cam, mm:
If the angle of rotation of the eccentric cam is not limited (a ≤ 130°), then
where δ is the tolerance of the workpiece size in the clamping direction, mm;
Dgar = 0.2…0.4 mm – guaranteed clearance for convenient installation and removal of the workpiece;
J = 9800…19600 kN/m – rigidity of eccentric EZM;
D = 0.4...0.6 hk mm – power reserve, taking into account wear and manufacturing errors of the eccentric cam.
If the angle of rotation of the eccentric cam is limited (a ≤ 60°), then
2. Using tables 5.5 and 5.6, select a standard eccentric cam. In this case, the following conditions must be met: Fz ≤ Fh max and hTo≤ h(dimensions, material, heat treatment and other technical conditions in accordance with GOST 9061-68. There is no need to check the standard eccentric cam for strength.
Table 5.5 - Standard round eccentric cam (GOST 9061-68)
Designation | Outer eccentric cam, mm | Eccentricity, | Cam stroke h, mm, not less | |||
Angle of rotation limited to a≤60° | Angle of rotation limited to a≤130° |
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Note: For eccentric cams 7013-0171...1013-0178, the values of F3 max and Mmax are calculated based on the strength parameter, and for the rest - taking into account ergonomic requirements with a maximum handle length of L = 320 mm. |
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3. Determine the length of the eccentric mechanism handle, mm
Values M max and P z max are selected according to table 5.5.
Table 5.6 - Round eccentric cams (GOST 9061-68). Dimensions, mm
Drawing - drawing of an eccentric cam
DIY eccentric clamp
The video will show you how to make a homemade eccentric clamp designed for fixing a workpiece. Do-it-yourself eccentric clamp.
A clamp is a tool that allows you to fix a part during processing. Craftsmen often use various types of clamps in their work. Whether you are a carpenter or a mechanic who processes metal, there is always a need to use it.
This device is available in different versions, from universal to specialized. Relatively recently, a new modification has appeared: a quick-release clamp. Develops compression force up to 450 kg.
The task for all types is common - to fix the workpieces for processing or connecting to each other.
Like any other tool, clamps can be purchased at the store or made yourself. The second option is often chosen by professionals. It’s easier to come up with your own design than to look for an option for individual tasks.
Homemade clamps - varieties and manufacturing technologies
Angle clamp
Such devices are used to fix two objects (not necessarily the same size) at right angles, to connect them together in any way. These can be wooden blanks when gluing, or assembling using corners and confirmat.
However, most often, an angle clamp is used as a jig for welding metal parts at right angles.
For production you will need:
- steel corner 40 mm, thickness 3-4 mm;
- steel plates 40-50 mm wide;
- threaded studs, preferably hardened;
- rods for gates;
- nuts for the worm gear;
- welding machine;
- drill, taps.
We weld the corners to the steel plates at a strictly 90° angle.
We attach a worm structure to each side by welding. This is the same corner with a welded-on thrust nut or thickening, in which a thread is cut in accordance with the collar pin. The width of the working gap is selected according to the potential workpiece.
IMPORTANT! If the range of sizes of the parts being processed is too wide, it is better to make several clamps. Too much movement of the knob does not contribute to a strong fixation.
A collar pin is screwed into the working nut, after which a stop is assembled at its end. As a rule, this is a structure of two metal washers of different sizes. The stop should rotate freely on the pin.
Unique clamps and clamps are not so difficult to make with your own hands for various purposes for a carpentry workshop. A good set of clamp clamps is an important part of the tool kit when assembling products.
Unique clamp clamps - review
In the tool catalogs there are various unique clamps and clamps to solve these issues. However, given the prices, it is difficult to justify buying these clamps even if you only need them once. On the other hand, with just a few small pieces of wood and inexpensive accessories you can make your own special purpose, unique clamps.
In this and subsequent posts we will look at unique clamp clamps:
Any of these clamps can be easily created in the evening in a carpentry workshop. They are quite cheap and easy to make with your own hands (clamps).
Clamp (clamp) Cam:
You can see the cam clamp in the photo (above); the idea itself is not new. In fact, I've admired the simplicity of the design for years. The big advantage of this design is that it is easy to manufacture and does not create much pressure on the product. I know this sounds like the antithesis of a quality clamp. But in some cases, too much pressure on the product can distort parts of the design. The clamp consists of two jaws, an aluminum rod and a cam, see (photo on the left). One jaw is fixed rigidly to the end of the rod, and the second jaw (adjustable) moves along the rod to the required thickness of the workpiece. The cam lever is located in the adjustable jaw and rotates counterclockwise to lock the workpiece.
Fixed jaw. The first thing to do is make an incision in the back of the fixed jaw (Figure C). The width of the cut should be equal to the thickness of the aluminum rod. Insert and firmly pin the aluminum rod into the cut at the back of the fixed jaw. Using a band saw, cut a groove along the inside of the half and make rounded corners as shown in the sample.
Sliding jaw (adjustable) This clamp has properties that deserve attention. The first property is the slot that is created for the cam lever. The second property is a narrow slot formed by a band saw and having a hole at the end of the slot that protects the half from splitting. The slot allows you to increase the pressure from the cam lever on the product. The third feature is the cut for the aluminum rod at the back of the half. The back half is larger and has a deeper slot compared to the fixed jaw. To move the jaw longitudinally, release the cam lever, remove one of the pins and slide the jaw along the rod. Having selected the required thickness corresponding to the thickness of the workpiece, firmly fix the sliding jaw with a pin and cam lever.
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