Greetings, Samodelkins !
Maxim Kozlov, the author of the YouTube channel of the same name (” Maxim Kozlov “), has already shared with us with our own experience in various shaped joints of a tree using CNC. This method allows parts to fit together with high precision.
But relatively thin workpieces were nevertheless chipped off when joining and thus an uneven weakening of the contact was obtained. Last time, the author closed this issue until better times and used epoxy resin. But not so long ago, the master began to try inlay technologies or V-shaped inserts for turning work, which prompted him to think about joining wooden parts in a similar way.
A spiral conical cutter was specially selected for this purpose. The angle of this cutter is much more adequate for such a connection, and the working length even on the 6th shank is all 30mm, which is quite enough for most tasks.
After carrying out a series of calculations and tests on plywood blanks, the master came to the conclusion that this method makes it possible to connect blanks along any complex path without any difficulty. In particular, with the “zigzag” pattern we get something like a “swallow's tail”, only the workpiece itself tries to sit in the counterpart.
There is one trick here, which is offsetting the milling path. And this offset depends on the angle of a particular cutter. By the method of calculations and tests, it was possible to find out that for a given cone cutter of 4.5 degrees, the offset on both parts should be 0.2 mm. In this case, the correct connection is obtained when the faces of the blanks must line up in a single plane. Taking into account the glue, the offset should be slightly increased to 0.25mm.
In the end, as you can see, everything came together as it should. We proceed to further tests on wood. The dough pieces are a thermal tree, which, by the way, was just stuffed with internal cracks. But this is why trial training tests are made so that there are no problems in battle.
Accordingly, the connection itself is obtained by flipping one of the parts so that the angles of their edges are in antiphase with respect to each other. This makes it possible to set completely different trajectories of the contact line, including closed ones, for which all this was actually started.
Moving on to a thicker material, the author decided to make a lathe blank, which, unlike a conventional shield, would have a high bond strength and would never fall apart. By the way, this is a great way to create boards for serving boards, for the same pizzas, for example, which, as a rule, all go away from constant washing.
Of course, in this case, both time and material consumption increase, but the result is original, and besides, the reliability is at a height.
The profile itself turns out to be incredibly clean, since in the course of deepening the cutter, it goes through the entire height of the workpiece every time. And due to the conical shape of the cutter, there are no resonant beats and, in principle, they cannot be.
The tool did an excellent job with milling the material by 25mm. Parts are not milled to the base by 0.5 mm, and as a result they are simply ground on a drum machine.
In the meantime, the whole thing is sticking together, we will prepare another pair of blanks for contrasting connection from dark thermal oak and honey thermal ash.
Initially, the author planned to make a set of coasters for hot dishes, but in the end he decided to put the material into small plates, or even saucers. In the case of hot coasters, the workpieces had to be relatively thin – about 10-12mm. For this, the final gluing could be dissolved on the face on a band saw and get twice as many products. Thus, by connecting a relatively thick material, you can significantly speed up the process to obtain thin products.
Since the connection is quite complex, it is worth paying special attention to gluing. All planes must be coated with glue.
While the glue is drying, let's go back to the first piece. It was decided to trim it on both sides to remove all protruding parts.
It was not at all a pity to distill such a workpiece into sawdust, since the thermal tree selected for this test had terrible internal flaws – cracks that threw up problems already at the milling stage.
As a result, the foreman put a saw blade for fine cutting and decided to saw off the defective parts with cracks so as not to get problems in the future. Of course, we had to forget about the symmetry of the product. Let's go around the perimeter and make a hole for the finger.
Thus, using different patterns for the path of joints, you can give a simple product +1 to the complexity and +100 to the strength.
Now let's go back to the thick billet of two types of thermowood. The first step is to grind off the protruding glue. In principle, it is sufficient to do this only on one side when it comes to further processing on the CNC. But it was decided to try double-sided processing on this workpiece. Therefore, the product should be as correct as possible, all corners should be straight so that you can make a revolution without losing the axis of the product.
Let's start external milling of the product shape.
Next, we move on to internal milling. Here the author followed the same principle, although in the case of plates, it is much more efficient and faster to use special cup cutters.
As a result, from a relatively small workpiece, we get such semi-finished products in the amount of 4 pieces, which you just need to divide and get rid of the technological part.
And since everything was fixed by eye, the alignment still escaped a little. Now the workpieces need to be slightly modified on a lathe, returning the alignment of the sides and removing the traces from the cutter. Just for such cases, it is worth making a stock in the main diameters of products during design.
Further, according to the worked out scheme – we grind and cover the whole thing with oil. The oil is applied to a clean and dry sanded surface. The composition must be applied in a uniform thin layer. And since we are working with a thermal tree, we can not be shy, as it absorbs a lot.
Since these products are for the kitchen, the oil was chosen appropriately – for countertops and kitchen utensils.
The composition is as natural as possible. The basis is linseed oil, and there are no heavy metals and other nasty things. Also, this oil has high mechanical stability, which is important for a brittle thermowood, and increased resistance to products such as coffee, red wine or fruit juice.
After 10-15 minutes, remove excess oil and leave for polymerization in a ventilated room. The second layer can be applied no earlier than 12 hours later, and complete polymerization occurs in 7-10 days.
These are such interesting products as a result. Thank you for attention. Until next time!
Greetings, Samodelkins !