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A little example as described later. The processes for the construction of a machine for grinding the mirrors which is discussed below require some basic knowledge of mechanical, electrical engineering and electronics not always known to most people. By this I mean that anyone who decides to follow the construction of such a device by following in whole or in part my descriptions will do their own risk because some solutions are not very "orthodox". For my part therefore decline all responsibility.
One of the major difficulties that meets the one who is going to undertake the construction of a machine for the processing of the mirrors is definitely the reduction of rotation speed of the electric motor which drives the rotation of the plane. Another difficulty lies in finding a suitable motor. Of course everything can be solved very trivially by purchasing an appropriate engine equipped with mechanical reduction and maybe an inverter which allows the variation of the same speed, or in an even more simple by purchasing a kit that allows the assembly of the entire machine effortlessly any problem.
For people like me take these things as a challenge, buy everything and meet in the regurgitate is not even considered. Of course if I had found a recovery engine with an attached reduction it is not that I would have discarded but the guiding principle has always been to try to do everything by myself and when you can use just recycled materials. Although it may seem strange, this means that often the money spent are well above the amount that you would be spending for the equipment over. But it is always the same speech also the mirror finished perhaps would agree to buy it ready to say the entire telescope, But we know that those of us like to complicate their lives to learn something.
The reduction of the speed of rotation I have resolved using a motor of a washing machine, two pulleys and two belts for the drive drum, with the construction of two axes machined on the lathe and with an electronic motor speed reducer. The photos and movies that you'll find below will serve to clarify that I speak;. But let's degrees.
Since I recovered an old washing machine motor, a pulley and a belt. Another pulley and another belt I bought from a company that is responsible for the recovery of ferrous materials. The pulley diameter is 30 cm while the motor shaft has a diameter of 3 cm. This means that connecting the motor pulley to get a reduction of 10:1 then repeating the operation with another pulley get a reduction of 100:1. The problem stems from being able to connect everything in a timely manner. In order I have built the lathe two axes which I equipped with two ball bearings for each and that I placed on the wooden supports as shown in figure.
Axis of photos bearings 1 https://postimg.cc/image/eufet8mlx/
Axis of photos bearings 2 https://postimg.cc/image/qiubbwzfx/
Power washers 1 https://postimg.cc/image/okjc3f1kr/
Power washers 2 https://postimg.cc/image/atfrre9gj/
Power washers 3 https://postimg.cc/image/qq21ucnjr/
Box plywood 1 https://postimg.cc/image/tet1gvwqd/
Box plywood 2 https://postimg.cc/image/a6q3tt00d/
Box plywood 3 https://postimg.cc/image/5tg4chpvr/The whole was then inserted into a species of poplar box built in a multilayer 2 cm thick resting on an "old" desk that I lifted the top shelf.
Box placed on the support desk 1 https://postimg.cc/image/655qf2r3h/
Box placed on the support desk 2 https://postimg.cc/image/kedbif1u9/
Box placed on the support desk 3 https://postimg.cc/image/ynv6ko8dr/I urge to notice in movies that follow that in the first tests, the engine is powered by a transformer that supplies direct current at a little less than 20 volts.
Film box in the first multilayer film testing https://youtu.be/qFmmt4EQ858
Film box multilayer particular axis https://youtu.be/J8IDpzRTIvwI carved a circle at this point 60 cm always in plywood diameter which constitutes the turntable. Said plate is not directly connected to the axis of rotation but rests on three wheels arranged in a nylon 120 degrees and is dragged by a wooden cruise directly connected to the axis of rotation as it appears from the accompanying photos. This not to weigh directly on the axis of rotation with the weight of the dish and of everything that is loaded on it.
The axis of rotation acts on it by means of wooden joints that form a sort of gimbal to compensate for the small but inevitable shortcomings of perpendicularity between the axis and rotating floor. The following figures I make it up well.
support wheels in 120 degrees https://postimg.cc/image/pxbv3iwyt/
rear view turntable https://postimg.cc/image/xy0n1e7nv/
support for dragging turntable https://postimg.cc/image/aq2k6i2k7/The motor speed variation I obtained by a varlight for incandescent lamps bought to brico for ten euro. The adjustment is not fine, affected, for example the mains voltage variations and with a very low number of revolutions sometimes the engine will not start but overall the operation is satisfactory. Keep in mind that without this measure the motor would turn to 11500 rpm, this at least according to the data shown on the plate applied thereto,. Among mechanics and electronics reducing the minimum speed that can not get to the turntable it is about 10 rpm, speeds that almost never use, Normally I do turn around 30 or 40 rpm.
To those who request could come up with the outline of the necessary electrical connections which however are easily found on the internet. Of course it is always the rule that everyone is responsible for what he does, dropping the whole thing if you do not have enough skills to do everything safely and in any case, I repeat that not all the solutions I have adopted are very orthodox. If among you there is an electrical maybe could also suggest to everyone to let loose and have to use some other method. In any case, in the days in which I write these notes, we are at the end of April 2017, It is on newsstands an electronic magazine that published an electronic circuit for controlling AC motors with brushes like the motor of a washing machine that I used in my project. It seems that the adjustment will have no loss of torque even at low rpm. The kit if I remember correctly it costs about 30 €.
As you can see in the movies the machine is also equipped with an oscillating arm that allows to obtain a translational movement of the tool towards the mirror (or mirror against the tool) which greatly resembles the movements obtained in handmade workings. When machining fact try not to depart too much from those that are the classic rules that are followed in the manual processing, a considerable help me anyway gives the POLSIM program that provides plausible information about the results that can be obtained by varying certain processing parameters such as amplitude of past, mutual positioning between the mirror and tool, etc... certain is that the checks should be done fairly frequently to avoid disappointment which are not lacking. Basic, during polishing and for obtaining a good ball, It is a good adaptation of the pitch patina. I have noticed that without this requirement the time of polishing which are also still long, They tend to become the Biblical and poor results. Another very important parameter is the hardness of the pitch patina. I happen to use a too tough coating that did not fit in the mirror during the process and the results were disastrous.
In any case, the swinging arm is kept in motion by a motor for a wiper recovered from my work colleague by some car wreck. Said motor is held in position by a headframe built with 4 clips from 8mm threaded rod from a sufficient number of dice and two steel plates bought at brico. The whole is then fixed to the support plane. The axis of said motor is then secured in an iron section bar that moved from the motor produces a circular motion which transmits the motion to the oscillating arm. By adjusting the point of attachment of said section you can vary the amplitude of the oscillation.
Eccentric movement oscillating arm https://postimg.cc/image/b7vb4onsr/As you can see in the movies all required mechanical machining for example for the obtaining of the joints, of the rotation axes, some weld points for joining the parts etc.. and I'm sure this will discourage many of those wanting to achieve said machine. But to them I can say that in reality, nothing prevents to realize all wood by replacing the axis on which is hinged to the swinging arm and the necessary joints, with, for example, of sufficiently sturdy hinges to buy brico to which precisely connect the wooden arms. If adequately lubricated said hinges perfectly serve the purpose. For this engine is not necessary a mechanical reduction of the number of revolutions as such reduction it is already present on the device. However, a speed variation slightest get the energy supply it with a power supply weblog GBC can deliver different voltages all around 12 Rated Volts of batteries of the machines. In any case, be aware that it is precisely this engine that is slightly undersized as power and that sometimes I saw "lag" in the polishing processing with the pitch and cerium oxide on a mirror of 300mm I'm currently working. In some cases it is just blocked but I must say it was extreme situations, the oscillation amplitude was the maximum allowed, and this requires the maximum effort of the motor, also between glass and tool there was hardly more abrasive and this created a sort of suction effect. Normally, however, it works great and honestly performs its task.
From the experience gained in that I said machine can tell you consider it very good and useful in the roughing stage up to processing with finer abrasive. I used it up to a grain 1200 I've got the surfaces with a fine satin finish. Even as you can be seen in one of the movies I wanted to try with the glass utensil and cerium oxide. Well if you do it with due caution (the dangers of bonding glass or brutal grooves are always lurking) The results are incredible, when you are switching to polishing with pitch just a quarter of an hour of work to be able to catch a glimpse Ronchi with the quality of the curve obtained. It get then to a perfectly polished surface still requires hours and the machine's working hours. However, and just to give you an idea, the mirror 300 I am currently working mm, required that the grain 120 onwards ie 220, 400, 800, 1000, 1200 about an hour of actual work for each grain but in the end had a really beautiful area. Everything looks very nice and fast, however, keep in mind that an incredible number of times I had to go back to the grain 400 and sometimes even to the 220 to remedy some scratches that I found myself working with the finer grits.
The real trouble, however, usually starting with the pitch and the next stage of polishing. Let it be clear hour of polishing is normally more than enough to have a fairly glossy surface to allow examination of the goodness of the curvature of the surface by means of Ronchi, but often this is far enough away from the sphere. Yet, by controlling the surface with a spherometer equipped with a clock dial able to appreciate the hundredth mm are unable to appreciate the slightest movement of the needle.
In some cases I found myself reaching the ball in a short time, while in others the same seemed impossible to achieve. Various attempts are due to the fact that often got out of frustration are often turned back by the abrasive sharing for example from 800 to look closer to the ball faster sought. Now I am almost certain that the most likely causes of these insucessi are to be charged to a poor adaptation of the patina and too hard pitch.
Summing, in order to realize this machine, that is not my invention (at least in good part) but it comes from a movie seen on the internet, it is necessary to work on the lathe two axes together with other small mechanical machining which in any case do not believe require large sums even by going to make do from a professional turner.
However it is also possible, for example by purchasing from the internet but better it would be somewhere rottamatore, of cruises for washing machine already equipped with board. In such a case it would be enough to build the disks in multilayer of suitable diameter to be fixed with screws of the cruise to replace the pulleys which are instead normally sold without axis. The solutions can be many, just a little bit of fantasy. It is certain that all these materials should obtain them otherwise recovery costs start growing so dizzy.
Then, in the solution adopted by me, with regard to the turntable only the two axes are surely the most problematic part of the rest is solved with a little bit of a multilayer jigsaw and a bit 'of screws.
That said I hope I was clear enough on how I made it all. Of course it's available for any questions or suggestions for those intending to try to carry out the work or for those who want to know for curiosity.
Also for the curious and for those who want, It follows a series of films with the machine in action.
processing 300 mm grana 120 https://youtu.be/9jsZ8Nw2jCM
processing with grit 220 https://youtu.be/zRFs5S4VmaI
processing grain 800 https://youtu.be/MPgDZBaEYQ0
processing grain 1200 https://youtu.be/VcMmsc2bCus
processing cerium oxide https://youtu.be/8lmXSOI75SQ
machining tool with a reduced diameter https://youtu.be/rp8KnXQAt7M
Lucidadura with cerium oxide https://youtu.be/sbsLFHtpdlUHello everybody
Giuseppe Mura
Dear Joseph, I can only thank you and get you the necessary compliments.
propio yesterday I tried some good project ,but they were too complex or
or simple yet unclear and questionable results.
I think I will copy but not in toto,having already everything necessary
I am a serial accumulator of industrial wastes!
A greetingUh, wow Joseph lavorone…
bravo, beautiful creation…
is in fact only in the last video with pitch and cerium oxide and tool full diameter is seen that the motor eccentric fatigue lot…It would no doubt a scooter with a few watts more…for very good rest… See you soon…ciao
hello Uraniborg, thanks for the compliments.
Even in the future, if you were to type needed my help or suggestions you have only to ask.
Hi everyone. hello BART
Excuse me but I was not aware of your surgery.
Thanks to you for the compliments.
In fact, the wiper motor is what in the various processes is slightly undersized but in the vast majority of situations if the weel.
The real problems stem from being able to understand what adjustments taken in the various situations that arise.
As I mentioned earlier a big hand me from the program POLSIM, but I assure you that often is not enough. Anyway I'm happy to have it built and have it available for my experiments. And, also I have “tinkered” deal with the special software POLSIM, more than anything else to begin to realize the dynamics at play, and the effects of various settings on the processing. But even as you say then, real mastery and proper management of the machine, the only acquire with the actual use of the same…
thanks Gim took advantage subito.ho an electric motor with a reducer which makes 30 rpm.
for the dish are too many or few?the arm of the tool as a percentage how much faster
should turn? sorry if I have not explained properly hello Uraniborg.
About thirty revolutions per minute is in fact the rotation speed that most use. In practice only during the roughing step to increase the speed of one revolution per second and even more by placing the mirror above and passed with a very decentralized in the past as "chordal" of handwork. This allows me to dig very quickly, but just as in manual processing the ball you get is not very good. Once you get close to the desired depth, to regularize the past alternately 1/3 center with the center of the mirror over to past the center of the center long almost to ½ placing the mirror under. Usually the excavation using the I make the grain 80 and the surface with regularization 120 and with 220. Step to the next grits always alternating mirror above and below only if the spherometer tells me that the surface is sufficiently correct. With regard to the movement of the arm, the speed is approximately one pass per second. I get small variations fueling the engine with voltages ranging from 9 volts to just under 20 volts (I do not remember the exact value).
Reading these lines you'll think of mirrors I worked there so many and indeed it is. As soon as I started this adventure with my colleagues I have blank various mirrors or should I call them pieces of glass, just to understand the functioning of the whole. The first pieces were pretty thin glass max 15 mm circa. Then we were able to procure from the glass 20 mm from which a disc we obtained from 20 cm in diameter, and this was the first and only time that we brought to parabolizzazione. I am currently working on a 300 mm.
So if you find yourself with this engine 30 revolutions per minute of which specify neither power supply they ( in many volts funzuina? you brush? He works for DC or AC ...) you can build yourself actually think of a rotating plane. I'm sure you will be of great help but remember that at least so far have not been able to find a configuration that in the process of polishing stably bring the ball.thanks Gim clarifications .the motor is an asynchronous from 0/5 hp 220v 1400 rounds.
but I also would have another with the same characteristics but 2hp.nelle last lines speak
polishing,It will be done by hand? The engine ½ hp in my opinion is more than enough. Keep in mind that my engine washing machine if I remember correctly a rated power of approximately 450 watt, then more power but very similar to yours, I just do food through a varlight (your that I know can not do it). This allows me to get 30 revolutions / minute of the plate that, having regard to the mechanical reductions, They should be approximately 3000 rev / min motor, then approximately 1/3 the number of rounds that are obtained by feeding in 220 volts. This should correspond to approximately one hundred watts actually paid, therefore much lower than the power supplied by your. Honestly, I never bothered to make a measurement, as is indeed feasible with a simple tester. As I got to say, when the pot turns around 30 giri / min, They are able to block the rotation with one hand. This, however, I consider it a virtue not a flaw. If not, just think what would happen if the other hand we would end up randomly brrrr ......
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As for the polishing I always I make machine-although with some difficulty to be able to get a decent ball, and the 200 mm are also able to parabolizzarlo.
Anyhow, after polishing with the turntable, nobody will prevent you to switch to manual processing if you were in difficulties in the sphere before and then the parable.Keep in mind that today (as already I documented here by myself in some remote intervention Forum) with less than 100 EUR you buy from an inverter 750Watt with contenutissime size of a contactor of magnitude 1, able to be fed with 220 volt single phase, and which generates a truly three-phase output with a full speed adjustment in frequency of an asynchronous motor. So without loss 2/3 the power that is experienced with the washing machine by two-phase engines started with the classic starting capacitor.
And if the above link, in time, does not find that page more, (given that the advertisements disappear over time), sucuro effect would be to search Google for the words: “Vector 0.4kW inverter toshiba” looking then found that the model is precisely what provides power 230 volt single phase, but provides a three-phase output, for feeding a classic three-phase motor and economical as is the type worm (for example Bonfiglioli, and not only).
It came to my mind to be able to use the drive I have a half-hp three-phase asynchronous
so it would be a step forward,a better one step?to vary the laps I had thought of pulleys for use with single-phase motor. in such cases the use
the machine is convenient to vary the rpm record door mirror?sorry questions
perhaps trivial ,but I want to fully understand the potential.A mechanical reduction still does it take to lower speed would not pair.
GIM can surely enlighten you better.
I saw that Gordon Waite uses the table in a speed range of 40 rpm in roughing 5 or 6 rpm in parabolizzazione.
So maybe I adopted the reduction would have been able to make me turn the floor at full speed, and then reducing it with the inverter, but remaining within a good mechanical torque, and the possiobilità to go a 10% over the maximum speed, as usual inverters make it possible.
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