If you often do construction and finishing work, then you probably have to clean any surfaces very often. It is no secret that this is done with ordinary sandpaper, which becomes unusable in a very short time. If you compare the price of one sheet of sandpaper and a circle with Velcro, the price will be exactly the same, only the circle has a diameter of 12 centimeters, and the leaf is three times larger than this circle.
Watch the video on how to make three Velcro discs from a sheet of sandpaper
To work we will need:
- 1 round disc purchased;
- a sheet of sandpaper of standard size;
- double sided tape;
- scissors.
We need a base to which we will attach sandpaper and tape.
Then we take double-sided tape and cut off a large piece, which we glue to the very center of our circle. The tape needs to be very, very sticky, otherwise it won't hold.
Now we cut off about 8 small pieces of tape and glue them around the perimeter.
Now remove the protective film from the tape.
We take our sheet of sandpaper and turn it over with the rough side facing the table surface.
We glue our workpiece into the very corner of the sandpaper. Be sure to glue it in the very corner, otherwise we will waste a lot of sandpaper in vain.
Now let's cut this whole thing out.
The disk is almost ready, the last thing left is to make holes in the disk. To make holes, take a drill and any wood drill.
Now we put any piece of wood on the table, put it in reverse on the drill and start making holes.
Our sanding disc is ready, now you can attach it to the machine and use it.
This approach has several advantages. Firstly, it’s cheap, and secondly, you don’t need to run to the store if you run out of round Velcro discs. Thirdly, you can cut a disc from the sheet if the desired mushroom content is not on the counter.
Grinding metal parts with an abrasive tool in most cases is a finishing operation that ensures high surface cleanliness and quality. It is also used for roughing work - cleaning workpieces from scale, removing irregularities on castings, smoothing welds - as well as for sharpening all kinds of cutting tools.
It is easy to mechanize this work at home using an electric drill or drill, securing the appropriate abrasive in the chuck. But sometimes just what you need is not at hand. However, the most common ones can be made with your own hands.
For sanding small items, simply a piece of sandpaper wrapped around a metal holder is often sufficient. To prevent the skin from being twisted, one edge of it is fixed in a special cut. Winding on a rod is performed in various ways, obtaining a tool of one shape or another. In some cases, it is advisable to use rods with an annular protrusion: it prevents the sheet from slipping during operation.
From scrap materials and some waste, it is possible to make abrasive heads of various shapes, intended for processing and finishing shaped surfaces. The heads are formed from abrasive powder - dust-like waste that accumulates under sharpening devices. They should be washed carefully to remove too fine particles and dust from the materials being processed. Iron filings are removed with a magnet wrapped in a plastic bag: from time to time the magnet is removed, and the sawdust adhering to the bag is washed off with a stream of water.
The finished powder is dried and sifted through a fine metal mesh. Then the abrasive is mixed with a binder - epoxy resin or silicate (stationery) glue. The resulting mass is brought to complete homogeneity. The mixture is filled into pre-prepared molds, similar in configuration to the surface being treated. The material for the molds will be a paper cup, a pound of plastic film or foil, and a cartridge of cardboard impregnated with paraffin. A recess or through hole is squeezed out of the abrasive mass that fills them - under a metal leg for mounting in the chuck. Such a holder is glued onto epoxy, or can be pressed into the mass itself during molding. If the finished working head is not coaxial with the leg, it should be ground while rotating with a coarse abrasive.
Sharpening cut-off cutters or saw chains requires thin discs that fit between the teeth. They can be easily obtained by gluing together two sheets of sandpaper on a fabric backing with the reverse sides. It is better to do this with epoxy glue: it will saturate the fabric and further strengthen the grains. While the resin is curing, the bag is placed under a flat, heavy object.
The resulting disk is not suitable for cutting narrow grooves in hard materials - others are needed, with grains not only on the sides, but also on the inside. You can also make such a tool yourself.
For example, a disc one millimeter thick is obtained by impregnating four layers of gauze with epoxy, on each of which abrasive powder is sifted through a metal mesh. After making such a “sandwich”, it is placed between sheets of polyethylene (epoxy does not stick to it) and left under the load until the resin hardens. If necessary, the outer surfaces of the disc can also be coated with abrasive. The final shape is given with metal scissors. The finished discs are secured to special metal mandrels or to an ordinary bolt with a cut off head using nuts and large-diameter washers.
For final high-quality or decorative sanding, make rotating abrasive brushes. First, a cylindrical base (beech, oak) is turned out, holes are made in it for the leg, as well as parallel cuts, into which strips of sandpaper coated with PVA glue are inserted. If such work has to be done often, the base should be turned out of metal (duralumin) in the form of a glass with cuts, a rubber cylinder with similar cuts is placed in it, into which the petals of the skin are inserted. All that remains is to throw a washer and nut onto the axial threaded rod; when tightened, the rubber cylinder will compress, firmly grasping the petals. With a glass diameter of 35 mm, you can install 16 petals.
After fine grinding, it is sometimes necessary to polish the product. Of course, a felt circle is indispensable here. However, scraps of cotton or woolen fabric sewn in 6 to 8 layers are also suitable. Such blanks are placed on the mandrel rod until the desired overall thickness is obtained.
First, I’ll briefly go through the points, if you don’t change your mind, then I’ll write in detail. I'm afraid I won't be able to manage it in the evening :)
1. Circle - cylinder Approximately f200 X 30 width - maximum. I plan to add a profile later - this is always done.
Yeah :) That's good. The straight profile is the easiest to manufacture.
Press form. For small volumes, the mold undergoes maintenance for at least 45 units. In case of increasing the volume of the mold, it is advisable to chrome plate it followed by grinding. The durability of the chrome plated mold is approximately 150-200 pressings.
2. I planned to try regular garnet sand, which is sold for sandblasting. In our area it’s not so easy to buy what you need, and it’s cheap.
You need to be careful with the components. If you want to have a predictable result, then it is better to work on one or two types of abrasive. Preferably a factory-made abrasive with the required dispersion and constant chemical composition (a quality certificate is desirable, but not required). It is better to refrain from abrasive, which is shoveled into bags in a nearby quarry. Using the correct basic components (abrasive and bond) will prevent damage to nerve cells in the future. :)
3. I don't know. That's why I created the topic. I was thinking of trying some kind of glue - if prompted, or a polymer melt. The bond should be soft, sand that wood (also soft)
This is ambiguous. The main requirement for the bond is to “correctly” hold the abrasive. Grinding occurs due to wear of the abrasive, and not due to the bond. The bond can enhance or weaken the effect of the abrasive. For example, a tool on ceramics and FFS. The characteristics of the tool are the same. But after grinding with a tool based on FFS, the surface will be cleaner, because... The resin has a slight polishing effect.
I tried an ordinary stone with silicon carbide - green - so it started to clog in an instant - and that’s it (((.
Most likely, the circle was solid with low porosity
4. There is a press, What is a thermostat in relation to the situation? Something to heat and control - I have... - a set of heaters of different shapes and an Aries controller for them.
When using a binder that does not require heating (epoxy resin, liquid glass), the question of a thermostat disappears by itself. When using binders made of thermoplastics and thermosets, you will need a stove that allows you to reach a temperature of 200 ° C. When using phenol-formaldehyde resins (bakelite, FFS), the accuracy of maintaining temperature throughout the entire volume of the oven should be plus or minus 2-3 degrees. When using thermosets (FFS), a finished unreinforced circle can be obtained, as a rule, in two ways: cold pressing and hot pressing. In the first case, a sample of the mechanical mixture of components is loaded into a mold and pressed. The workpiece is removed from the mold and placed in an oven for curing. In the second case, a sample of the mixture is loaded into a mold and pressed on a press equipped with heating plates. After a certain time, the finished product is removed from the mold. Having tried hot pressing, I almost immediately abandoned it and completely switched to cold pressing.
If the abrasive surface of a factory grinding wheel has become unusable over time, do not rush to throw it in a landfill, because you can give it a second life. Moreover, this is done very simply, it takes a minimum of time, and you can save money, especially if you often have to do various grinding work at home or in the workshop. Why not try it?
How to make a grinding disc: work progress
First you need to remove old abrasive elements from the surface of the disk - this can be done with a knife. Then you need to sand the entire outer side of the circle well so that there are no bumps or bulges left.
The next step will require preparing a new abrasive surface. To do this, you can use a piece of sandpaper of the desired grit. Place the grinder disc on the sandpaper, trace the outline (including the central hole) with a marker or pencil, and then carefully cut out the circle with scissors. It’s better to do several laps at once so that you have a reserve. A small hole in the center can be made using a regular stationery knife.
After this, simply install the disc on the grinder, place the prepared circle of sandpaper on top and press everything with a quick-clamping nut. That's all - the tool is ready for use. Homemade sanding discs will come in handy both at home and in the workshop. The most important thing is that they can be made very quickly and they will cost less than their store-bought counterparts.
