Hobby CNC router do it yourself. Humanities for the humanities

At first, I wanted a boat. Having read the reports on the kayaker site, having seen enough of this beauty, I imagined how I dissect the shervotera on the morning surface, and so on. Along the way, in order to somehow stir up the remnants of the inter-aural ganglion, I sadly picked my lessons on COMPASS.

Later added video clips on YouTube , reading the forum on cnc-club.ru , and gradually somehow it turned out that I wanted a machine.

To explain how much I didn’t own the material at that time, and the desire to get the result was so strong that I seriously considered building a plywood machine with guides from a profile pipe with a drive on a bicycle chain. From the tool there was a grinder and two drills. As a workbench - a desk.

At once I will say that I am not going to describe the principle of operation of the stepper motor and the principles of operation of the CNC. This is already written enough by people more prepared. I will remember my delusions and problems that I had to face. I am not saying in a word or hint that the theory is not needed, the idea is that enough experience has been accumulated on the Web so that an amateur can build a sufficiently functional unit for woodworking houses and possibly on soft metals. I am aware that there may be inaccuracies in the article, but I write as I understand. If there are amendments - thanks to me.

Also, I'm not going to lay out the drawings of my machine. First, they are not complete. Secondly, there are no problems to model the hobby machine on their own, receiving a bonus in the form of an understanding of the construction of their offspring. Thirdly, the published models of hobby CNC with reports on the construction of the web abound. Much more thoughtful and better made.

So, back to our us. I started to model my future machine. A portal construction with a working area of ​​1500x1000x100 mm was assumed. The first to hit the guides of the profile pipe. After I built the carriages that would roll along the guides on ball bearings, and tried to imagine how I assemble them in kind, I realized that on my knee I would never expose them not only exactly, but at least somehow parallel.
Cylindrical SFCs were not considered initially, since, when fixing guides only at the ends and the lack of communication between them, to provide at least some stability of the router, according to the portal purelogic.ru , the diameter of the guide should be at least 5% of the length. Better than 6-10%. That is, even with a guideway length of half a meter, its diameter should be 25-50 mm.

The cylindrical guides on the support, although much better, however, also have their drawbacks. First, the polished metal shaft is simply bolted every twenty centimeters to the duralumin base, without providing sufficient rigidity. Secondly, the linear bearing ball contacts the guide only at one point, which leads to increased wear. Thirdly, the linear bearings themselves play. It is considered that the cylindrical guide on the support ensures accuracy in the tenths of a millimeter. I have heard that these guides on these machines are used for protective shields.

Well, the best option for CNC router is HGR guides. The guide is screwed directly onto the frame, which increases the rigidity of the structure, the bearing balls move along a special chute, which allows a large increase in the contact area, as a result of which the wear is greatly reduced. The carriages for these guides are thought out and executed more carefully, and, as a result, they promise accuracy in hundredths of a millimeter.

As for me, I then chose the second option: the SBR16 guides. Take a normal at that time crushed toad. Now I think that it was necessary to wait a month and write out, probably, them, but what's done is done. I will grow big - I will change.

Were bought:

  • 2 pieces of SBR16 - 1500 mm 112 USD
  • 2 pieces SBR16 - 1000 mm 65 USD
  • 2 pieces of SBR16 - 300 mm + 2 pcs bearings SBR16UU 48 USD

Of course, linear bearings were bought four per axle, but with their acquisition a scandalous story occurred, and I won’t tell you the exact price now. The fact is that at that time I was a very inexperienced and very greedy buyer for Ali-express, and when I was looking for guides for the first time, I came across a somewhat muddy image of a set of one-and-a-half guide and a pair of bearings. Omachev from such freebies, I ordered four sets at once, deciding that I had outwitted everyone and well done. When they brought the box, obviously not one and a half meters long, in which there were eight linear bearings, I went crazy again and opened the argument. The seller pretended to be a fool for a while, hinting at my frivolity, but before the site intervened, he offered to return some of the money. I figured the amount was adequate, and agreed to a partial refund. I do not remember the amount now. In general, the bearings cost about five dollars apiece. That is, 5x12 = 60 USD.

After I decided on the guides, the question arose: how would I pull-push this thing? When it came to design, all cycling fantasies disappeared somehow by themselves, and the choice turned out between a corrugated belt, a toothed rack, a screw with a trapezoidal thread and a ball screw drive.

For some time, the HTD toothed belt, widely used in the amateur machine tool industry, was considered, but I still could not find out how much it stretches over a length of one and a half meters. Later, I came across a method of dealing with stretching, but the choice had already been made. But the one who invented it is a bloody genius. Without a hint of irony.


The screw with trapezoidal thread, firstly, has a small pitch that slows the movement of the carriage along the axis, secondly, I understand that everything is not just there with adjusting the nut to avoid backlash, and, thirdly, I could not find out What effort is needed to overcome the friction force between the screw and the nut. The only thing that was found was the statement that the ballscrew works easier by thirty percent.

I just did not find an inexpensive rail. And in the end, he stopped at ballscrews. I think that this program is optimal for a beginner. Fixing requires only at the ends, gearboxes and clamps need not be invented. Stiffness is sufficient. At a speed of 40 mm / s does not vibrate. I am sure that with an increase in speed up to 50-60 mm / s it will not vibrate.

Costs for ballscrews:

  • 1 piece of ball screw SFU1605 - 1000 mm 44 USD
  • 1 piece of ball screw SFU1605 - 300 mm 30 USD
  • 2 pieces of ball screw SFU1605 - 1500 mm 50 USD
  • 4 pieces coupling with polyurethane insert 16 USD
  • 4 sets of supports for ball screw BK12 + DF12 24 USD

Thus, 450 dollars were spent for transfers and guides by me. All the non-iron, brands to take for the construction of the knee considered unnecessary. I will not lie about super-accuracy (though, and who will check?), Because the machine is in an unheated room, but the frequency of several 200 mm circles from fifteen-millimeter plywood is, if the eyes and the Soviet caliper do not lie, one-tenth millimeter.

On this introductory part finish. In the next I will try to tell you how I designed the nodes of my machine and what was my guide.

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