Vlasenko 13-11-2007 14:12
A question for those who themselves glued tapes on a cloth basis ...
What did they glue? Glue area width? Seam durability?
About the angle of the bevel of the gluing zone and cleaning it from the abrasive, you can not mention
Thanks in advance for the first hand info...
sergeant 13-11-2007 14:24
In search.
discussed several times.
Vlasenko 13-11-2007 15:16
Sergey, Sorry...
I use the search, oddly enough I know how ...
I'm interested in specific infa and the results of using it from those who did it PERSONALLY, and not rehashing from other sources and discussion ...
sergeant 13-11-2007 15:37
people told what and how glued.
I why also sent in search.
Vlasenko 13-11-2007 15:48
quote: people told what and how glued.
I have read these posts...
A trio of posts on pva, momentum and cyacrine, plus a few links to knaif and foreigners - not a lot and everything is known ...
But from "personal hands" about
quote: Seam durability?
Generally zero
Vlad Klem 13-11-2007 16:11
So I'm also wondering if anyone has experience gluing? I tried to glue both the moment and cyanoacrylate and PVA and even special two-component adhesives (specifically for gluing tapes) and they all broke, if not immediately, then after a very short time of work. It is not for nothing that firms such as Liner-Belt or Clarey keep the gluing technology secret.
So if anyone has a stable positive result, please share.
SiDiS 13-11-2007 17:41
I have more than 4 years of experience using glued tapes. The experience is positive. Cons: on small grit numbers it hits noticeably (from 250 grit)
It tears extremely rarely and, oddly enough, not along the seam, but behind it, if the skin is thin. On a skin with a rigid base, it either does not tear at all (99%), or along the seam. This happens at a very high load and / or on the sharp edge of the workpiece.
For gluing, thin synthetics with cotton (from thin shirts) and "moment" are best suited.
Vlasenko 13-11-2007 17:55
Dmitry, as far as I understand, your "contact moment" proved to be better than PVA with thermopolymerization?
The fact that it tears after the seam is quite understandable ... There is a step on the edge of the seam and on it (from the side of the abrasive) the base wears out faster during operation ...
Vlad Klem 13-11-2007 18:04
SiDiS
So I didn't understand. You glue in a butt joint with an overlay, or overlap and also with an overlay.
SiDiS 13-11-2007 18:36
Yuzayu usual standard "moment". PVA, and even with terpopolymerization, I have not tried, the moment is more than enough. I glue end-to-end on an oblique (about 45 gr.). The thickness at the gluing point increases by about 0.1 mm
Bayan 13-11-2007 21:14
Literally today, I also tried to glue butt on a cloth base, but it didn’t work with an overlap - I couldn’t clean off the abrasive. I liked the result very much - there is almost no fight. I glued it on 88. Let's see how long it will live ...
grga 14-11-2007 02:30
For several years now, I have been overlapping glue, first cleaning off the abrasive. At the lower end completely, at the upper one partially, there is no beating, the tape does not break. PVA glue, but this is not necessary, because. I also enjoyed using others, it's just that PVA is more accessible to me. I remove the abrasive with a piece of an old grindstone with brutal grain sizes and with the help of 646 solvent (in a respirator with filters, of course). The angle is approximately 60 degrees. , overlap width 30 mm.
There is a little trick when cleaning: at the place of gluing, folds are made (with the abrasive outwards) after 3-4 mm, and when folded, the abrasive flies off them with a bang, you just have to rustle them with a large pebble. Then, having such cleared stripes, the rest flies off easier. The main thing is not to damage the fabric, and therefore refused to use the grinder - it is difficult to catch the moment when, instead of forming a circle, it begins to remove layers of fabric from the tape.
Gadyukin 14-11-2007 12:54
I tried to glue in an overlap (about 20mm), glue Moment, removed the abrasive from the lower end using a drill with a diamond nozzle. The tape is still alive, the only problem is the lack of a normal knife, made from domestic. Now there is an idea to glue it with rubber-based mastic (in tubes for a gun) intended for mounting heavy panels made of artificial and natural stone, after drying it remains elastic. By the way, on the new purchased tapes, such an innovation appeared - gluing end-to-end from the bottom is glued with some kind of slippery synthetic fibrous material, the fibers on it are oriented along the tape.
Vlad Klem 14-11-2007 15:26
Maybe the point is also that all Corvettes have a tape 100-150mm wide.
Therefore, the bonding area is quite significant, as a result, the specific tension load of the tape is small. I have a tape 50mm and even 30mm. And the load on it from the tension roller is decent. Maybe that's why, glued on their own, the tapes are torn by gluing.
SiDiS 14-11-2007 15:29
I have a tape width of 40-50 mm
Vlasenko 14-11-2007 15:38
quote: I have a tape 50mm and even 30mm. And the load on it from the tension roller is decent.
And due to what load is decent? Is the pull roller of small diameter something and there is not enough contact area of \u200b\u200bclutch for pulling at a reasonable tension?
How do you glue? Butt or overlap?
SiDiS 14-11-2007 16:31
due to the smaller cross-sectional area / length of the seam than for tapes with a width of 100 mm
Vlasenko 14-11-2007 16:46
quote: due to the smaller cross-sectional area / length of the seam than for tapes with a width of 100 mm
That's not what I meant when I asked about the load ...
To remove metal across the entire width of the tape, there is some kind of load per unit width (friction from peeling with an abrasive) ... With the same specific force, the use of narrower tapes requires less effort to pull it ...
So I’m wondering why Vlad gets a decent load from TENSION ... IMHO this may come from the need to increase friction on the pull roller (so that there is no slippage), and friction depends on the contact area on it (and, accordingly, on its diameter) ...
Vlad Klem 14-11-2007 18:37
Error in reasoning. Take any material for example Ф=20mm and Ф=50mm and pull it with a constant force. Where will the specific load on the material be greater? Similarly with a narrow and wide tape. The specific load of a narrow belt will be as many times greater as the width of the belt will be smaller. With the same belt tension load. These are the pies.
Vlasenko 14-11-2007 19:11
quote: Error in reasoning.
And what is wrong?
The speed of rotation of the pulling shaft is constant ... The power on the shaft is obviously higher than the total load on the tape ... (practically does not affect the speed of the shaft) -> pulling force per unit width of the shaft is also constant -> With the same load per unit width of the tape at the place of removal we get that per unit. the width of the seam, the load is also constant ...
Yes. at the same time, the total material removal rate will depend on the width, but in real life you press the wedge not with all the dope, but in order to shoot with high quality, and this is a certain optimum in terms of pressure of the workpiece to the abrasive, i.e. on a wide tape, press harder ...
Big_hunter 14-11-2007 19:25
Well, I'll tell you. Previously glued (now I know that it was cyanoacrylate) "second". But with preliminary impregnation of the surfaces to be glued with it. The tape works, but it still breaks over time. Having visited the carpentry workshop of a relative, I saw a grinder 5 meters long and a tape 25 cm wide. The tapes are glued by themselves. Interrogated with predilection staff. Now I do this:
gluing in an overlap with a depth of 1.5 cm, I cut the tape in the place of gluing on both sides at an angle of 45 degrees, wash off the abrasive with 646 solvent, glue titibond 2, spread it to achieve a single axis of the tape in the place of gluing, cover the place of gluing on both sides with a newspaper and five minutes (approximately) I bake with an iron. The main thing here is not to overbake, so that the glue does not become brittle. Esssno need to take into account the thickness of the tape, the temperature of the iron, environment etc. In short, experience is a friend of difficult mistakes ...
Prior to the introduction of best practices, I used a titibond type liquid nails, also holds with a bang, but the gluing is thicker and the tape hits a little at the junction.
Gadyukin 15-11-2007 19:46
Is there a photo of the packaging of Titobond 2?
Vlad Klem 15-11-2007 20:17
If you want a picture, we have them. This glue is called Titebond II Premium Wood Glue.
I don't know how it sticks. But you can try.
sergeant 15-11-2007 20:25
But I know..
I made a bed on it. this is some kind of pipets and not resin. impossible to rip off.
Vlad Klem 15-11-2007 20:54
Well, if even "Sergeant" has adapted this glue for the sexodrome (and the loads there are decent), then perhaps tomorrow I'll take a walk to the "Kashirsky Dvor", and buy some pizirek entiva glue.
And then you can three stops on the tram and get to Moskvoretsky.
Vlasenko 16-11-2007 02:27
quote: perhaps tomorrow I'll take a walk to Kashirsky Dvor, and buy some pizirek entiva glue.
Vlad, after the experiments, write down the results - it's interesting, after all ...
Vlad Klem 16-11-2007 19:17
So, I took a walk today to the "Expostroy" on Nakhimovsky Prospekt. Thankfully close to home. Titebond II... for some reason it wasn't there (in small packages) in large 3l ones. in bulk, but there I was offered a newer adhesive of this series "Titebond 111", they say that, compared to Titebond II, it sticks together one and a half times stronger. From Expostroy I drove to the Moskvoretsky market (several stops on the 52nd tr-se). And there is this Titebond II wagon and a small cart, in all sorts of packages. So I bought it too. Now boom to experiment.
On Moskvoretsky, one seller, carried away by all sorts of adhesives, fillers and protectors, offered me glue (polyurethane) from the "liquid nails" series, which, as he assures, if you glue two steel sheets and then try to break, then the gap will not be on the glue, but for steel. Exaggerates of course, but an interesting thing. I wrote down the glue data, I'll dig into the I-net, I'll look at the characteristics.
Here are the Titebonds:
Vlad Klem 18-11-2007 22:50
I was at Kashirsky Dvor today, buying some metal. Previously walked through the rows, bought sandpaper 36; 80 and 120. rolls 200mm wide. just get 4 tapes of 50mm. I will practice gluing. In any case, if it works out, it will be three times cheaper than in Clarea. And yet, they sold felt, ribbon. Width 50mm. length 2m. and 7mm thick. Bought one to try out. I'll try to glue it on the grinder. I wonder if anyone here has used such tapes.
Andy 18-11-2007 23:34
Bare felt without warp? Won't stretch?
We are waiting for the results of gluing the sandpaper. (triple savings sounds delicious)
Vlasenko 19-11-2007 12:20
quote: Bare felt without warp? Won't stretch?
I think that if necessary, a simple keeper tape can be sewn along the edges from the inside of the felt, although 7 mm is a bit thick ...
It would be ideal to make such a ribbon from felt cloth from an officer's overcoat ...
Vlad Klem 19-11-2007 01:02
I didn't think about "stretching". But the proposal from the side of the substrate to attach a keeper tape is the very thing. Or maybe duct tape.
Ramzay 1 19-11-2007 11:30
Hey everyone, at the weekend I glued the tapes with a moment (crystal) and a titibond.
all work great, only with the titibond a little hard seam hits.
glued the abrasive into the overlay 15 mm removed with a solvent.
Question: there is a solvent that easily removes the abrasive, after I need to scrub hard.
Ramzay 1 19-11-2007 11:32
quote: Originally posted by Vlasenko:
Bare felt without warp
I glued the felt onto the worn tape with 88th glue, everything is ok
The abrasive belt of the grinding machine is a consumable material, it is necessary to change it quite often with the active use of the grinder. If you have a sheet of sandpaper of suitable grit and length at hand, and there is no desire to buy a new tape, then you can always glue it yourself. Let's see how this can be done.
In order to glue the tape for the grinding machine you will need:
1. Long sheet of sandpaper.
2. A small vulcanizer, you can make it yourself.
3. Pencil, ruler and scissors.
4. Glue.
Preparing the tape for gluing
1. A tape of the desired length and width is torn off or cut off from the sandpaper sheet.
2. At one of its ends on the back, non-abrasive surface of the tape, at an arbitrary angle to its side, mark the cut line.
3. Cut the tape along this line.
4. The ends of the tape are aligned by twisting one of them at the same time by 180˚.
5. On the back of the uncircumcised end, a cut line is also drawn, using the cut end as a ruler.
6. Cut off the second end of the tape along the drawn line.
7. Be sure to check the accuracy of the coincidence of the cut ends when they are closed into a single tape web.
8. On one of the ends of the tape, parallel to the cut line, the line of its inflection is drawn at an arbitrary distance from its edge.
9. Bend it tightly along this line onto the back of the tape.
10. Check the uniformity of the bend.
11. Use a knife to remove grains of abrasive from the surface of the fold of the tape.
This is necessary to make it more visible.
12. In the same way, mark the fold line at the second end of the tape at the same distance from its edge as at the first,
bend it and remove the abrasive from the fold line.
13. Straighten one of the bent ends of the tape and put it on the platform of the vulcanizer included in the network. The edge of the platform should coincide with the line of the former fold of the tape from which the abrasive was removed.
14. Press the end of the tape to the platform with some kind of flat load and wait for the glue that holds the abrasive grains on it to loosen. Their slight blackening can serve as a guide.
15. Scrap the abrasive from the heated end of the tape with a knife.
16. The same operations are done with the second end,
after which the vulcanizer is turned off and the connection of the ends of the tape “overlap” looks like.
Gluing
For gluing the ends of the abrasive tape, it is recommended to use Moment 88, an especially strong waterproof adhesive.
Glue it like this:
1. Apply glue to the surface of one of the ends of the tape, cleaned of abrasive.
2. Distribute it over the surface with the other end of the tape, also cleaned of abrasive grains. As a result, the adhesive covers the surfaces of both ends prepared for gluing.
3. After five minutes, the overlapped ends smeared with glue are applied to each other, they are squeezed tightly,
and then check the quality of bonding.
4. If the glue still “does not hold” and the ends of the tape “diverge” when they are tensioned, then the glue is again applied to the tape, waiting for it to “dry”, and then again press the ends together. This is done as many times as necessary so that the ends of the tape hold each other tightly when they are pulled. Such a multi-layered application of glue makes the tape more rigid in the place of gluing, where there are no abrasive grains.
On large and small industrial enterprises there has always been a need to have grinding machines in the equipment park different type, including tape. IN last years, in connection with the development of small businesses, handicraft workshops, and simply to perform small jobs for grinding any parts, desktop small-sized grinding machines began to be produced belt type. The thing is necessary, of course, but one nuance spoils everything: the high cost. And this applies not only to foreign models, prices for domestic counterparts also bite sensitively. Here, involuntarily, many craftsmen begin to think about how to make a tape grinder with their own hands.
How does a grinder work?
Desktop grinding machine belt type or in a simple way, a belt grinder, is driving device, where the role of the power unit is performed by the electric motor. Designed tool for processing, finishing and grinding flat surfaces, removal of a layer of rust or paint coating present on the workpieces. With its help, burrs and sharp edges of steel, cast iron, aluminum or non-metallic parts are processed.
Design
There is nothing particularly complicated in the design of the belt grinder. The device consists of a motor, drive and guide rollers. A grinding or roughing belt of the required grain size is passed through them.
When the engine is turned on, the drive roller mounted on its shaft begins to rotate, and through the tensioned working tape, the rotation is transmitted to the guide rollers. Pressing the part to be processed in the working area to the belt, the operator performs the required operation, changing, if necessary, the position of the workpiece relative to the surface of the belt.
By adjusting the distance between the guide rollers, it is possible to process surfaces with defects of different depths. With prolonged use, the sanding belt may not stretch much. To compensate for possible slack, the design on one of the rollers provides tensioner. Usually, such a function is assigned to a roller located at the same distance between the master and the slave.
The package of the grinding machine includes a support table, which also performs the function of a surface for fixing the workpiece. As a rule, such a table should be able to rotate 90 degrees about one axis. In this case, the processing of two perpendicularly located planes is obtained without reinstalling the part on the support table.
While safety glasses are required for these machines, it is a good idea to fit clear acrylic glass to protect your eyes from scale particles, paint flakes, or metal dust. For example, you can see the installed protective glasses on industrial machines, where a round emery stone is installed as a working element.
Definitely requires a grinder control panel! For safety reasons, it is recommended to mount it on the machine frame in close proximity to working area operator. Portable machines are equipped with a sturdy steel stand with mounting holes on the base, allowing you to fix the unit on a wooden surface.
If you look at the details of the design, you can immediately notice a certain visual instability of the assembled grinding device. Departure of lateral dimensions of the installed rollers significantly exceeds the bearing surface on the base. In addition, the absence of a support table makes it difficult to effectively process relatively large surfaces, and holding a part on a canopy is inconvenient and rather dangerous.
The increased length of the working tape leads to additional losses due to friction. It is necessary to use a larger power unit in the drive, and this increases the cost of electricity. The tension unit is simple and functional. Adjusting the tension is a matter of seconds. The machine is equipped with interchangeable grinding nozzles, with which grinding can be done even on internal surfaces. Despite this, the cost of 100 thousand rubles. makes me think.
Ribbon selection
To choose the right belt grinder, it would be nice to first decide on overall dimensions surfaces of the products to be processed, and then get acquainted with the dimensions of the sanding belts available for sale.
Endless sanding belts differ in three ways: length, width and grit. Produced on this moment the size range of sanding belts for such machines is as follows: 610 mm, 915 mm, 1230 mm, 1600 mm, 1830 mm in length, in width the dimensions are limited to 50 and 100 mm, although others can be found.
In any case, the following criteria must be met:
- The tape must be on elastic fabric backing.
- Maintain limiting angular speeds of at least 1500 rpm.
- Possess high abrasive resistance.
- The ultimate relative tension at break is not less than 15%.
- Heat resistant for long periods of use.
When choosing a tape, it is necessary to take into account that the most optimal size sanding belts for a homemade grinder is 1230 mm. Shorter abrasive belts wear out faster because they do not cool down sufficiently in time. idle move. As for the longer ones, their use will lead to an increase in the dimensions of the entire structure, which is unacceptable; however, it does not provide any improvement.
The parameters of the mechanical tensile strength of the tape are very important. The use of composite tapes, even if glued with the most advanced composition or double tape, absolutely not allowed! When the joint is stretched during operation, the tape increases in length and the tension weakens. In this case, the tape may come off the guide rollers or break, and at such a speed this is fraught with serious consequences for the operator and others. Taking into account the high speed of the tape along the surface of the guides and the drive roller, the applied specific force on the surface of the abrasive should not exceed 0.8 kg/cm 2 . Approximately this parameter corresponds to the mechanical strength of electrocorundum sanding tape: 800-900 MPa.
Advice: before installing the tape on the grinder, it is recommended to hang it on a cylinder with a diameter of about 60 mm. This ensures the natural stretching of the abrasive element before work.
Do-it-yourself grinder: drawings with dimensions + assembly instructions
When developing Special attention is given to the configuration of the rollers, the method of fixing the product and the optimal power of the power unit. More about this.
Production of rollers
Particular attention is required to the manufacture of the main, leading roller acting as a pulley! It must be sufficiently massive. This will allow during the starting torque to avoid unnecessary jerk, due to the present inertia of the rest state. The speed is dialed gradually to the desired values. If we take into account the use of a standard power unit in the design of the drive, with slip not exceeding 9%, at a nominal 1500 rpm, the speed will be no more than 1400 rpm maximum.
One more nuance! Steel or cast iron is not suitable for the manufacture of the leading part, because when starting the engine there will be a painful load, or it will not be able to scroll through a too heavy blank at all.
There are two options to resolve the issue:
- To make a hollow steel roller to reduce weight according to the principle: larger diameter- Deeper cavity. The exact dimensions can be calculated using a reference book, although special accuracy is not required.
- The second option: making a roller from duralumin brand D16 and higher.
On the pulley, it is desirable to carve an end ditch, whose dimensions will be identical to the dimensions of the tape intended for use. This will help prevent uncontrolled tape slippage if the rollers are not positioned correctly in the plane of rotation.
Of great importance surface roughness rollers. Recommended limit values: Ra1.25-Ra2.5. Higher roughness will cause premature wear of the belt base, and roughness below the specified limit will contribute to unnecessary slippage during long-term operation.
Installation of rollers must be carried out using bearing assemblies closed type based on self-centering bearings with a fixed outer ring. The ingress of abrasive or other particles on the roller shaft with this installation is excluded. When selecting bearings, it is necessary to take into account the compliance of their bearing parameters with the maximum number rpm of the power unit.
The rollers can be fastened using conventional cotter pins or using a shoulder at one end of the axle, as prescribed by the standard. The drive roller must have a groove for a key common with the motor shaft.
Motor and turntable
If you are going to assemble a belt grinder with your own hands, then special attention should be paid to the choice of drive! Most often, a 0.75 kW engine is used (although up to 1.5 kW is not forbidden) with a speed of 1500 to 3000.
Please note that the belt may not withstand high speeds. As a rule, the power of the engine is chosen depending on the intended operations on the assembled machine. If roughing predominates, when the load on the drive is large, the power unit is set to be more powerful, but with fewer revolutions, and if just surface grinding is required, the parameters remain within the limits mentioned above.
The grinding process is characterized by considerable contamination in the form of microscopic dust particles, so the engine must be of a closed type with its own fan for blowing! Recommendations of "experts" on the use of the engine from washing machine used is better to ignore.
To design a homemade grinder, you need drawings with dimensions, in addition, it’s a good idea to think about safety and ease of use on assembled apparatus. This requires:
- Rotary table.
- Clamping plane with reverse side support tapes.
For the first task, the table bracket must be mobile, with the possibility of rotation by 90 degrees and fixation at the limit points. The recommended thickness of the table is at least 15 mm, it is desirable to use duralumin.
The machine frame ground near the support table is suitable for the clamping plane.
Grinder (English) literally - a crusher. Meat grinder is a meat grinder, rock (stone) grinder is a stone crusher; stick (wood) grinder - garden crusher of branches and rods into chips. But there is also a completely unambiguous meaning of the word grinder: in mechanical engineering and metalworking, this is a grinding machine. A useful household item. For example, it is impossible to manually guide a dull meat grinder knife on a whetstone. On a manual knife sharpener - somehow possible, with a solid working skill. And on the grinder - no problem. The same - if you need to grind a part of a complex shape without violating its profile. Or just sharpen scissors or a professional knife. different kind cutters for wood and metal are best edited on a grinder too. It is quite possible to design and assemble a grinder with your own hands, without having sophisticated equipment and skills to work on it. In terms of money, this will mean savings from 50-90 thousand rubles. up to 3-6 thousand USD.
To make a grinder yourself, you will need to order a maximum of 4-5 turned parts, and it is often possible to do without turning from outside at all. For example, how to make the simplest grinder literally from trash, see the video below:
Video: do-it-yourself tape grinder from trash
Or another option, how to make the grinder stronger and more resilient from scrap metal:
Video: scrap metal grinder
Disk or tape? And drive
Almost more varieties of grinding machines are used in industry than lathes. Emery known to all craftsmen - a motor with a pair of grinding wheels (or one circle) - this is also a grinder. For yourself at home, it makes sense to make either a disk end (plate) or a belt grinder. In the first, the abrasive is applied to a rotating HDD; in the second - on an elastic tape running around a system of pulleys and rollers. Disc is more suitable for grinding simple wooden parts and coarse or medium purity - metal. On a belt grinder, it is also possible to produce precise and clean finishing of profiled parts of complex shape, incl. large, see below.
A disc grinder is very simply obtained from the same emery or a motor of suitable power, see below. It is necessary to order an adapter from the motor shaft to the poppet shank grinding wheel on a metal base. or under chuck, then on the same motor it will be possible to build a mini lathe, see fig.:
A worn-out “plate” is suitable: a disc made of thin (4-6 mm) fibrous plastic is glued onto the edge of its side, and an abrasive is placed on it. How to make an end grinder, see next. video clip.
Video: homemade end grinder
The difference between a disc grinder and a belt grinder is not only in the possibilities of use. If you take ordinary home crafts, then a drive power of 250-300 W on the shaft is enough for a disk grinder. For small wooden parts - and 150-170 watts. This is a motor from an old washing machine, a straight (ordinary) drill or a screwdriver. But for a belt grinder, you need an engine from 450-500 W: three-phase with batteries of starting and operating capacitors. If it is supposed to process a large size, then the motor power is from 1-1.2 kW. Moreover, capacitor banks for both will cost a little less than the engine itself.
Note: a 100-200 W drive uses a mini belt grinder (see below) for fine dressing of knives, grinding / polishing jewelry, etc.
A drill or screwdriver as a grinder drive is also convenient in that it allows you to quickly change the speed of the abrasive (see below) with a standard speed controller. It is only necessary, firstly, to make a holder for the drill, rigidly fixing the tool. Secondly, an elastic adapter from the drill to the disc shank, because it is difficult to achieve their precise centering without special equipment, and the runout will negate the accuracy of processing and can damage the tool-drive.
Drawings of the drill holder for using it as a drive for a home metal-cutting machine are given on the left in the figure:
Since shock and irregular alternating loads on the drive in the grinder are an order of magnitude lower than, say, in lathe, the drill holder for it can be made of solid wood, plywood, chipboard, MDF, on the right in fig. The diameter of the mounting (large) hole is along the neck of the drill. It is highly desirable to use a drill without an impact mechanism and with a steel shell on the neck (for the installation of the front handle).
Coupling
For the adapter, you will need a piece of steel bar (not necessarily turned) of the same diameter as the shank of the grinder drive shaft, and a piece of reinforced PVC hose (garden irrigation) with a gap so that it is tightly pulled over the bar and shank. The length of the “free” hose (between the ends of the rod and the shank in it) is 3-5 cm. The length of the protruding part of the rod should be sufficient for a reliable clamp in the drill chuck. After assembling the coupling in place, the hose on the shank and rod is tightly tightened with clamps; can be wire. Such a coupling completely parries the misalignment of the drive and the driven shaft up to 1-1.5 mm.
Ribbon is still better.
A belt grinder allows you to do everything that a disc grinder does, and more. Therefore, further we will focus on how to make a belt sander with our own hands. Amateurs, focusing on industrial designs, sometimes make grinders very intricate, see fig.:
And this is justified: the design and kinematics of the belt grinder are very flexible, which makes it possible to successfully use improvised materials and old scrap metal. You just need to follow 3 principles:
- Do not do as in the second photo from the left: the tape with the abrasive side should only touch the workpiece. Otherwise, the abrasive will eat both the bypass rollers and itself. The accuracy and cleanliness of processing during one working operation will be unpredictable;
- The design of the machine must ensure uniform belt tension, regardless of the nature of the operation being performed;
- The speed of the belt movement must correspond to the nature of the operation being performed.
Kinematics and design
As mentioned above, there are many designs of grinders. Thinking about what and how to build a grinder for yourself, it is better to focus on industrial samples designed for fully mechanized for accurate and clean grinding of large-sized profiled parts: since the propeller blade of an aircraft or wind turbine “skins” as it should, then it will cope with any other work.
Kinematic schemes of grinders for the specified purpose are given in Fig.:
Basic kinematic diagrams of belt grinders (grinders)
Pos. A - the most complex and perfect, with three rocker arms. If the length of the tensioning roller rocker is approx. 2 times less than the working one, then by adjusting the tension of the springs, it is possible to achieve a uniform tension of the tape when the working rocker moves 20-30 degrees up and down. By tilting the bypass rocker, firstly, the machine is reconfigured for tapes of different lengths. Secondly, in the same way, you can quickly change the belt tension for different operations. The working branch of the tape can be any, except for the one running from the drive pulley to the tension roller, i.e. a grinder with 3 rocker arms is both horizontal and vertical at the same time.
A scheme with a coaxially swinging rocker (pos. 2) is simpler, cheaper and not inferior in processing accuracy to the previous one, if the length of the rocker between the axes is at least 3 diameters of the workpiece. In order to knock down the profile by grinding, the course of the rocker arm is limited by stops within 10 degrees up and down. The clamping of the tape to the part is most often gravitational, under the weight of the rocker with a bypass pulley. It is possible to quickly change the tension of the tape within certain limits by pulling the rocker up with a weak adjustable spring, which partly compensates for its severity. The grinder of this scheme can work as a grinder for small parts from a sliding table. In this case, the rocker is rigidly fixed horizontally, and working surface tape will run around the bypass pulley. According to the scheme with a coaxial rocker arm, for example, a fairly popular BTS50 grinder was made. The disadvantages of the scheme are, firstly, the technologically complex rocker arm hinge coaxial with the drive shaft. Secondly, the need for an elastic band: if you make the bypass pulley sliding spring-loaded, the machining accuracy drops. This disadvantage when processing small parts is completely eliminated by an additional tension roller, see below.
A scheme with one misaligned rocker arm in industry is used quite rarely, because. in principle, it does not allow to achieve a uniform tension of the tape. However, it gives an accuracy that is quite sufficient at home and allows you to build a very good simple grinder.
What's good for what
Now let's see what is possible to "squeeze" out of this or that scheme from the point of view of an amateur master. And then we’ll try to figure out how to make a belt for the grinder ourselves and do without custom-made turned parts.
3 rockers
Competent amateurs build their grinders exactly according to the scheme with 3 rocker arms, on the left in fig. below. Far from all propeller blades are ground, but in this case another advantage of this scheme operates: if the grinder is used as a vertical one, then the working branch of the tape is elastic. This allows a skilled craftsman, for example, to guide cutting edges and blades with literally micron precision.
In industrial grinders for home use, the 3-arm pattern is also widely used (in the center) for the same reasons. Repetition of them independently in most cases is quite possible. For example, drawings of the popular KMG grinder abroad can be downloaded.
The dimensions, however, are inch - an American typewriter. In any case, it is possible to use an angle grinder for the drive (on the right in the figure, it is quite suitable in terms of power) with homemade pulley and rollers, see below.
Note: if you are making a stationary drive, try to get a 2-3 speed asynchronous motor from a worthless washer with a horizontal tank. Its advantage is low turnover. This makes it possible to make the drive pulley large diameter and thereby prevent belt slippage. A slippage of the tape in the work is almost certainly a damaged part. Most washers with 2-3 speed 220 V asynchronous motors are Spanish. Shaft power - 600-1000 watts. If you come across one, do not forget about the standard phase-shifting capacitor bank.
Coaxial rocker
In its pure form, grinders with a coaxial rocker are not made by amateurs. The coaxial hinge is a complicated thing, you can’t make an elastic band yourself, and a purchased one is expensive. Grinders with a coaxial rocker at home are most often used in the variant for fine precision work from the table, i.e. with a rigidly fixed horizontal beam. But then the need for a yoke as such disappears.
An example is a mini grinder, the drawings of which are given in Fig.:
Its features are, firstly, an overhead bed for the tape (pos. 7), which greatly expands the possibilities of use. For example, a planer iron is straightened on this grinder with an angle stop literally by itself. In this case, the grinder works, so to speak, like a self-propelled donkey (emery bar). After removing the bed, we get a grinder with an elastic band for precise grinding / polishing of rounded small parts. Secondly, the tension shaft (pos. 12). Clamping it with a groove with nuts, we get a relatively fixed tension of the tape for working with the bed. And having released the nuts, we put the grinder into the mode of gravitational tension of the tape for fine work. The drive is not necessarily through a pulley (pos. 11). Can be screwed directly behind the drive shaft shank (pos. 16) from the drill through the adapter, see above.
A specialized tool grinder (for example, for aiming and dressing turning tools) generally loses any semblance of the original scheme. A high-speed motor is taken for it (a power of 200-300 W is enough). The drive pulley, respectively, of small diameter. The bypass pulley, on the contrary, is made larger and heavier, for inertia. All this together allows you to reduce the runout of the tape. The tension roller for the same purpose, plus for greater uniformity of the tape tension, is taken away and spring-loaded with a long, not very strong spring. How to make a cutter grinder, see the video below.
Video: cutter grinder
One rocker
In amateur practice, grinders with misaligned rocker are good because they do not need precise details at all. For example, hinges can be made from card loops. At the same time, the accuracy of processing remains sufficient for ordinary amateur requests.
The original scheme in this case is also modified: the rocker is rotated 90 degrees, carried up and spring-loaded, on the left in Fig. It turns out a simple vertical grinder. And, importantly, it works without problems with a home-made inextensible tape. Both tension spring (in the center) and compression spring can provide belt tension. Its strength is not important, as long as the tape does not bend excessively during operation. No adjustments are required during use.
Consumables and parts
The only one consumable for a belt grinder - tape (not counting grease for bearings and joints. The tape can be ordered in the desired length (see at the end), but you can also make it yourself from emery cloth on a textile basis. It is highly desirable - flexible, unimpregnated. In general, the procedure for making a tape for a do-it-yourself grinder is this:
- We cut off the workpiece - a strip of the desired length and width.
- We prepare a mandrel (not necessarily round) with a length along the generatrix slightly less than the length of the tape.
- We circle the mandrel with the workpiece inside out.
- We bring the ends of the workpiece exactly end-to-end and securely fasten.
- We put a piece of glue stick for a hot glue gun on the joint.
- We heat with a building hair dryer until the glue melts.
- We impose a patch of thin fabric on the joint.
- We press something hard through the Teflon film until the glue hardens.
There are three significant points here. The first is to use a rough PET film with a thickness of 25-50 microns (sold) instead of fabric on the patch. It is very durable, but try running your finger over a PET bottle. Not very slippery? A rough PET film under tension cannot be stretched over polished metal. And instead of a patch, it is better to seal the wrong side of the tape with a continuous strip of PET film with an overlap of 2-3 cm. The beating of the tape will be no more than 0.05-0.1 mm. This is less than from the thinnest calico and even less than the error in the thickness of the skin-blank.
The second - fill the finished tape into the machine and grind something obscene with it without strong pressure. The hem on the seam will come together, and the tape will become no worse than the branded one.
But most importantly - in terms of elasticity best glue for gluing the grinder tape is not expensive and difficult to use thermal or mounting, but ordinary PVA. If the tape is pasted over with a lining along the entire length of the inside, then its strength for PVA is more than enough. How to glue a tape for a PVA grinder, see the video
Video: gluing the grinder tape with PVA glue
Pulley
Generating ( side surface section) of the grinder drive pulley must be straight. If you use a pulley-barrel, then the tape will bend like a trough along its entire length. The rollers do not allow it to slip, see below, but the pulley generatrix must be straight.
A pulley for a grinder that is not designed for particularly precise work, firstly, does not have to be turned. In the scheme with 3 rocker arms, the beating of the tape from its misalignment will go out on the rollers before it reaches the working branch. In a simple vertical grinder, the belt runout will be sufficiently damped by the tension spring. Therefore, it is quite possible to make a pulley for a grinder without a machine, see video:
Video: drive wheel on a grinder without a lathe
The second is that the pulley, rollers and, in general, all the details of a home grinder can be made from plywood. In production, this is certainly not an option, even if the plywood grinder is offered for free with an additional payment: the grinder needs a salary, and the wooden grinder in the workshop will completely wear out before it pays for itself. But you won’t drive the grinder at home day after day in 3 shifts. And no tape slips along the plywood pulley. Incl. homemade. So you can safely make a grinder pulley out of plywood:
Video: plywood grinder pulley
It is much more important to correctly calculate the diameter of the pulley according to the speed of the motor and the required speed of the belt. Too slow running belt will tear the processed material; too fast - it will be erased by itself, without really processing anything. In which case, what tape speed is needed is a special conversation, and a very difficult one. In general, the finer the abrasive and the harder the material to be processed, the faster the belt should move. How the speed of the belt depends on the diameter of the pulley and the speed of the motor, see the figure:
Fortunately, for most abrasive-material pairs, the allowable limits for belt speed are quite wide, so choosing a grinder pulley can be easier:
Video: which wheel is needed for a belt grinder
Rollers
The rollers of the grinder, oddly enough at first glance, are its most important details. It is the rollers that keep the tape from slipping and ensure its uniform tension across the width. Moreover, there can be only one video in kinematics, see, for example, the video above about the cutter grinder. Only barrel rollers will cope with this task, see below. But the “trough” of the tape after any roller should straighten out before it reaches the working area.
Rollers with flanges (sides, edges) will not hold the tape. The point here is not only and not so much with the misalignment of the axes of the rollers: the grinder belt, unlike the drive belt, must withstand, without slipping, the loads from the workpieces. If you make rollers with flanges, then, just touching something to the tape, it will crawl onto the flange. In the grinder, you need to use Type 3 barrel rollers (highlighted in red on the left in the figure).
The dimensions of Type 3 rollers are also given there. It is advisable to take the diameter of the rollers no more than 0.5 of the width of the tape (so that the “trough” does not go far), but not less than 20 mm of steel turned and not less than 35-40 mm of plywood. The tension roller (the probability of the tape slipping from it is greatest), if the working branch of the tape does not leave it, can be 0.7-1.2 in diameter of its width. Plywood rollers are made in the form of a thick shell into which the bearing is pressed; then the roller is mounted on the axle (in the center in the figure) and finished clean, see e.g. track. video:
Video: barrel roller for grinder
Not every turner can machine a profile barrel roller exactly according to GOST. Meanwhile, there is a way to make rollers for the grinder without significant difficulties. The same garden reinforced PVC hose will help out, on the right in fig. previously. On the roller blank with a straight generatrix, its segment is pulled tightly and cut off with a margin along the edges to the thickness of the hose wall. It turns out a roller with a complex generatrix profile, which holds the tape even better and gives it a smaller “trough”. Don't believe? Try to get into the graveyard of planes or missiles and dig into them. You will find rollers with exactly the same generatrix profile. It's just that the mass production of rollers of a complex profile is much more expensive than Type 3 barrels.
And another option
All critical parts of the grinder - one-piece belt, non-slip coated pulleys, rollers - can be purchased separately. They will cost not so cheap, but still not in thousands of foreign and not in dozens of native "leather jackets". The remaining parts of the grinder, either flat or from professional pipes, are made using a conventional bench drill or drill. Here is where you can order grinder parts:
- //www.cora.ru/products.asp?id=4091 - tape. Do lengths and widths at the request of the customer. Advise on abrasives and processing modes. The prices are acceptable. Delivery time - questions to Ruspost.
- //www.equipment.rilkom.ru/01kmpt.htm - spare parts (accessories) for grinding machines. There is everything, the prices are divine. Delivery - see prev.
- //www.ridgid.spb.ru/goodscat/good/listAll/104434/ - the same, but foreign-made. Prices are higher, delivery is the same.
- //www.pk-m.ru/kolesa_i_roliki/privodnye_kolesa/ - drive wheels. You can find suitable for the grinder.
- //dyplex.by.ru/bader.html, //www.syndic.ru/index.php?option=com_content&task=view&id=36&Itemid=36 – spare parts for grinders. Ribbons are not made to order - choose from the catalog. Rollers without axles; axles are sold separately. The quality is impeccable, but everything is very expensive. Sending - within 2 weeks to the border. Then - their customs, our customs, Ruspost. Total ok. 2 months It may not reach if some local bureaucrat considers the goods to be sanctions. In this case, there are no problems with the return of the payment due to the complete absence of real opportunities for an ordinary citizen to receive one. (2 ratings, average: 5,00 out of 5)
Ready-made abrasive belts for household grinders and home grinders can be easily bought at a store or on the construction market. That's just the price of the issue is not always satisfied. Yes, and the distance to the destination can be decent.
Therefore, it will be cheaper to glue abrasive tapes with your own hands. For home-made belt grinders, sandpaper abrasive belts also in most cases have to be glued on their own, since it is far from always possible to find the right size.
Some craftsmen prefer to glue the tape joint-to-joint, placing a sandpaper lining on the bottom. However, it is better that the seam is overlapped. How to glue the abrasive tape from sandpaper for the grinder and grinder, read on.
We glue the abrasive tape ourselves
First of all, cut the sandpaper into strips of the desired width. The length must be measured a little with a margin, taking into account the overlap, which is 2 cm. Another important point- the angle at which the parts of the sandpaper will be glued together should be “friendly” with the diameter of the installed rollers.
before gluing one piece sanding belt abrasive must be removed. To do this, moisten the place of gluing with acetone and leave for a few minutes. Then we remove the “grains” with the help of a hacksaw saw blade for metal.
At the second end of the sandpaper, you need to remove a small chamfer for better grip. You also need to clean the sandpaper with inside. Then you can proceed directly to gluing the abrasive strip for the grinder and LSM.
