Manufacturing.
First of all, I found the components for the hinge on which the grinder will rotate.
For a high-quality cut, the hinge must be strong enough and without the slightest backlash.
Found an old shaft and flange from the Volgovskaya pump and several bearings, including those killed.
I assembled such a sandwich in order to maximize the bearings between them.
I found a piece of pipe for the outer cage of the hinge.
It was a little too big in diameter, so I made a rip cut to clamp the bearings like a clamp.
Welded a couple of corners and drilled holes in the right places
The second component of the rack is a pendulum with attachment for a grinder. The grinder mount was bent out of a 2.5 mm strip.
The rest is made from a 20 x 20 mm profile pipe.
I welded the mount, trying to keep the grinder parallel to the plane of rotation of the lever as much as possible. To do this, when I was cooking, I inserted rods into the mounting holes - I controlled the parallelism along them.
The third component is the base. It is welded from a corner 3 2x 32 mm.
The two profile tubes 20 x 20 in the middle are guides for an adjustable stop, which should fix the workpiece.
The table was made from a plate 30 x 30 cm 3 mm thick, sawn into 2 parts. Attached to the base with M5 screws.
In the continuation of the table, a 3 mm plate is welded on the base. It is for attaching the return spring, and to level the table further along the guides.
After all the fittings and adjustments, I put the rack together.
This is how the grinder is attached.
On the one hand, it is screwed on with a standard handle, on the other - with an M8 bolt.
Adjustment of the grinder vertically - from above and below with two stops (legs from furniture).
The bearings are clamped in a cage with an M6 Bolt.
The yoke is screwed to the base with two M6 bolts.
The right hole is oval, so that the position of the clip can be adjusted.
Recoil spring - from Volgovskiye pads.
To prevent it from jumping off the mount, I made a galvanized clamp.
About adjustment:
In order to accurately mark the plane of rotation of the disc, I clamped two calipers into the grinder instead of the disc. According to them, you can accurately and clearly adjust the position of the grinder.
First, I set the plane of the disc parallel to the longitudinal groove in the bed.
For this, one of the holes for fastening the hinge is made oval (marked with an arrow).
Then he set the plane of the disk perpendicular to the table.
This adjustment is done with two stops fixing the grinder.
When everything became even, I made a cut in the table with a grinder fixed on the lever.
Now you need to make a stop to fix the workpiece at the desired angle. The blank for the stop was a piece of a 32 x 32 mm corner, the same one from which the bed was made. I welded a 2 mm plate to it.
In order to saw through a semicircular groove for the clamping bolt, I made a jig from the trim and drilled 3 mm holes in a circle.
Then on them with a 6mm drill.
I cut the jumpers between the holes with a hacksaw.
And he leveled it with a file.
Then he cut off the excess in a circle.
From the already unnecessary jig and 2 M6 bolts, I made a clamping bar for the stop. It is inserted from below into a groove on the bed.
It turned out to be such an emphasis.
It can be moved along the entire length of the guide groove and fixed at the desired angle.
I have not yet come up with the design of the clamp, while I use the clamp.
The cut turns out to be even, neat, at the right angle - just what I wanted.
Homemade author: Gleb from Minsk. Belarus.
Cantilever machine from a grinder
The base of the machine is a working table made of metal (steel or aluminum), measuring about 50X50 cm.If you are going, from time to time, to work with long workpieces or a metal sheet, then the width of the table can be increased or the possibility of installing an additional plane can be provided. To do this, you can use a retractable bracket, or a folding plane, which is normally located under the table and serves as its base.
A bracket is mounted on the table for attaching the grinder on a spring suspension. The force of the spring is selected so that it can hold the grinder in an inclined position at the height of the cutting disc from the workpiece at least 15-20 cm. When cutting, the tool should be fed to the workpiece with a small but tangible force.
The angle grinder is clamped in a box-type housing with screws. The dimensions and configuration of the pressure plates are selected in such a way that:
- easy access to the start button was provided;
- the tool was firmly held, and with the cutting force there were no beats and deviations;
- assembly and disassembly did not take much time.
Drawings of a homemade machine tool can be adjusted depending on the size and power of a particular tool
Here, only one thing is important - that the tool is held firmly and the plane of rotation of the disk is strictly perpendicular to the plane of the table. On the table itself, in the circle of rotation of the circle, a slot is made so that the working part of the tool freely enters it and does not touch the metal
Mounting option - "U" -shaped bracket with drilled holes in place of the standard threaded sockets of the grinder. When attaching the tool, two bolts and a handle are used, which serves to feed it into the cutting zone. This option is very convenient if the machine is made for one grinder, if you have to use another model, then it will be impossible to fix it, you will have to redo the bracket. The circuit with the changing dimensions of the console is also quite efficient, but it is more difficult to manufacture.
Electrical part
Since the grinder will be fixed from below, we will no longer be able to turn it on in the usual way. We will have to provide for the installation of the following elements:
- a clamp that will constantly hold the control key in the "on" position;
- socket for connecting the grinder;
- a control station that turns the electricity on and off at this outlet.
It is very good to use an industrial control room in such a design. This unit has two keys. The "Start" button is rather tight, which prevents accidental switching on. The large and soft "Stop" key allows, if necessary, to quickly turn off the device, reaching it with any part of the body.
And what, in fact, are we talking about?
Dozens of traditional designs of units for precise cutting of sheet, roll and long materials are known, this is not counting laser, etc. from the century of high technologies. We will further consider machines with an oscillating working module and a circular rotating cutting body - an abrasive or saw blade. Such cutting machines are called pendulum cutting machines. They are the most versatile (including suitable for broaching - conducting a longitudinal cut of limited length) and can be carried out independently in a shed and garage workshop. When they say "cut-off machine", then in the overwhelming majority of cases it is the pendulum (pendulum cut grinder in English) is meant.
Motor or angle grinder?
This refers to the drive of the machine - separate or combined in a monoblock with a working (cutting) body and a power transmission to it. A separate motor has the advantage that the swinging part of the unit - the rocking arm (pendulum, rocker arm) can be properly balanced, which greatly simplifies the work on the machine and increases its productivity; the latter is relatively weakly dependent on the cutting resistance of the material
In addition, the entire machine can be made suitable for intensive, round-shift work, which can be important for those who generate income with hands growing from where they need to and a head working as it should.LBM (grinder), as you know, can work continuously for 20-60 minutes
(depending on the model), and then a forced technical one to cool the tool. But for occasional use, angle grinder has a number of advantages:
- A sufficiently hardy and accurate cutting machine from a grinder can be made without turned parts and with a minimum of welding work or without them at all, see below.
- The basic tool remains suitable for manual work outside the machine.
- Power supply - single-phase 220 V from a household outlet.
- Starting devices and protective grounding are not required. only double-insulated angle grinders are widely sold.
- The external characteristic of the LBM collector motor is softer than an asynchronous electric motor with a squirrel-cage rotor, which saves motor power and electricity consumption. In most cases (except for cutting thick durable and / or viscous materials), it can be assumed that an 800 W electric grinder is equivalent to an asynchronous motor with 1.2 kW on the shaft (see below), and a 1300 W angle grinder is equivalent to a separate motor for 2, 2 kW.
- Cutting machines from angle grinders are lighter, more compact and transportable than with a separate drive.
- Inexpensive grinders are not equipped with speed controllers, but a regular speed control for a drill fits them (no more than $ 20; usually $ 5 - $ 6). "Frequency converter" for an asynchronous motor up to 2.5 kW costs from $ 50.
About speed regulation
Why regulate the speed of the disk? To not exceed the maximum linear edge speed and / or rotational speed indicated on it. Otherwise, the disc may not break, but its performance will drop dramatically, wear will increase, and the cut quality will deteriorate. Nominal speeds of rotation of asynchronous motors 2800-2850 min – 1 allow using conventional discs with a diameter of up to 350-400 mm and more, which gives a cutting depth of at least 150 mm. The spindle of the grinder turns much faster (from 6000 min – 1), and it is dangerous to put on it a conventional disc with a diameter of more than 160 mm. The cutting depth goes up to 50-60 mm, and the high-speed disc is expensive and quickly erases. Installing a speed governor solves the problem. Cutting performance and quality are not affected as are determined by the linear speed of rotation along the cutting edge.
About the name
LBM sounds "technically", but in fact it is inaccurate, tk. they cut a lot more with a grinder than they grind. The "angle drill" is even more unfortunate because to drill - drill, drill, for which angle grinder is generally unsuitable. The angle grinder is a tracing paper from English. "Angle grinder machine". But the English to grind in its meaning is much broader than all types of abrasive processing. For example, a meat grinder is a meat grinder. “To grind” has no exact Russian analogue; in the sense it is something like "shred to shreds in the back streets." In general, the vernacular "Bulgarian" is terminologically incorrect, but rather briefly, and it is clear what it is.
Safety rules when working with a homemade machine
During work, it is important to follow the safety rules
- The protective cover of the machine must cover the area in which the worker is located;
- Many people will want to do woodwork on a machine with their own hands. But you need to know that the special toothed disc is not designed for such a high speed and will wear out quickly. In addition, it is very dangerous to work with saw blades. To work on the machine, you need to use only special cutters for angle grinders with an abrasive surface.
Videos about several models of homemade machines from angle grinders:
Finally
A factory-made metal cutting machine for attaching a grinder can be bought on the Internet. But often they are made entirely of duralumin alloys and one should not rely on their strength. Backlash appears very quickly, and making an accurate cut, especially on hard metal, is quite difficult. At the same time, the price of such an installation is quite high - for the same amount you can make your own machine with much better performance.
Stationary cut-off saw from a grinder - the device is universal and does not require compliance with certain standards in the manufacture. You can develop your own version of the machine independently, but the proposed principle of a cantilever pendulum frame, on which the grinder is fixed, seems to be optimal for both amateur and professional work. A metal-cutting machine is much safer than a conventional grinder - the threat of biting the circle in the cut, pulling out the tool from the hands and skewing the workpiece disappears.