Have you ever tried making even a small wooden roof truss? Each of us has a very good idea of how it should look (especially those who tried to build their own house), but you try to assemble it…
This work is extremely long and laborious – grooves need to be made in one beam, spikes in another, sawn down the third this way, the fourth that way, and then assemble a single structure by placing its elements on glue or hammering in nails. Well, to assemble one farm is still here and there, but try to make a second one exactly the same. And 10-12 pieces are the same? It is quite difficult to maintain the geometric dimensions with this method of connection. The trusses are, to put it mildly, different, which in turn creates difficulties when assembling into a common structure. In general, such work should be carried out by specialists, and in our time it is not always possible to find them..
What are the solutions to this problem? We found two. The first of them is the creation of structures using metal toothed plates – MZP. Their use can reduce the cost of the structure, increase labor productivity, without reducing the quality of products. They are made by stamping from galvanized steel with a thickness of 1.2 mm or 2.0 mm. Then the plates are cut in accordance with the required dimensions (length from 50 mm to 400 mm with a step of 25 mm, width from 100 mm to 250 mm with the same step) and packed.
How is a structure created with the help of toothed plates? It’s pretty simple. With the help of a conventional circular saw, the boards are given the desired geometry, after which the structure of the future truss is laid out of them on special tables and the MZP is pressed in at the joints of the elements. Moreover, the plates are placed on both sides of the connected elements..
Design and calculation of structures with joints on the MZP is carried out, as a rule, on a personal computer using a special program. The resulting printout (drawing and specification of elements) is transferred to the workshop, where either whole trusses are manufactured, or linear fragments of trusses that are assembled (re-assembled) into a finished product at the construction site.
This technology, like any other, has its pros and cons..
Let’s start with the pros:
At the same time, for the manufacture of structures using MZP, it is necessary to have an almost perfectly flat area with dimensions corresponding to the manufactured elements and a special press in the form of a bracket with an appropriate hydraulic unit (the strength of the connections is guaranteed only when using special equipment for pressing).
The most widespread in foreign construction practice were MZP of the Gang-Neil system, and in the USSR, MZP-1,2 and MZP-2 connections were used, which were developed by TsNIISK im. Kucherenko. The main disadvantage of all MZP of the Gang-Neil system is that the connecting plate works in different directions in different ways, and with a load acting along the main axis, the bending strength of the studs is minimal. The Arpad type MW system (patent 1998, Hungary) is devoid of this drawback. Its main difference is that the axes of the pairs of pins, stamped into the plate, form a certain angle with the direction of the main load, and the rows of pins are located at an angle to each other. With such an arrangement of the teeth, when the unit is loaded, the phenomenon of jamming of the spikes in the wood occurs, which significantly increases the strength of the connection.
Despite the huge number of advantages of the new technology, the minimum wage is used little in individual construction. In spite of the fact that the assembly stand and the equipment for pressing the MZP are elementary and mobile, under construction conditions, as a rule, structures are not manufactured – they are made only in a workshop. And not a single company will take its equipment to the construction site to the customer in order to assemble 4-5 farms on site. The assembled large structures are transported to the construction site by a special vehicle, which means quite significant transport costs. Installation of large structures in place is possible only with the use of a crane, and not every individual builder has the opportunity to use a crane. So this solution is mainly used by large construction companies..
And what should small firms and individual developers use? The second way of solving the problem suits him perfectly. Despite the fact that this technology has been known in America for a long time, for us it turned out to be an absolute novelty. But she came to us not from America, but from Poland. It was presented to our market through its dealers by a company known to the domestic consumer for its fasteners – dowels, self-tapping screws, etc..
This time the company offered to the attention of the domestic consumer a huge collection of assembly parts for wooden structures. And they fasten all these parts of the wooden structures not with stamped spikes, but with self-tapping screws.
That is, they are all steel parts for a very different purpose and therefore of different shapes with holes stamped in them. The collection has universal elements – plates and corners (including reinforced ones) that can be used in accordance with your own technical problems and creative imagination, as well as special elements that allow you to fasten beams at right and arbitrary angles, install slopes, fasten beams together or fasten wooden beams to a concrete base. The use of such elements greatly simplifies the task of creating a complex roofing structure, and the work begins to resemble playing with a children’s designer – he cut wooden elements of the required configuration (here you can even do without a circular), purchased the necessary fasteners and assemble the structure using self-tapping screws. No “grooves and tenons”. It’s simple.
And even special qualifications are not required for this work – the main thing is to be able to hold a screwdriver in your hands. Yes, and there is no need to talk about this system for a long time – just look at the pictures to understand everything yourself.
Of course, we have shown far from all the fasteners offered in the collection, but we think that the given ones are quite enough in order to form a fairly complete picture of it.