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Mi "torno del pobre" tiene algunas mañas. Por supuesto, si fuera perfecto no sería "del pobre". Una de ellas es que, al usar como motor el taladro de mano, cuya velocidad es variable pero entre valores muy altos (1900-2500 rpm), en ocasiones no me sirve. Especialmente cuando la pieza a tornear comienza siendo una madera algo voluminosa y deforme. Si en esas condiciones la pongo a girar a 1900 rpm, puede ocurrir un desastre porque todo se sacude debido al desbalanceo.

Ese defecto empezó a resultar molesto y peligroso, a tal punto que me vi obligado a interrumpir otros proyectos para construir un reductor de velocidad. Comprar uno está fuera de consideración, porque no solo son muy caros, sino que además el trabajo de adaptarlo a mis necesidades sería tan grande como construir uno. Evalué distintas alternativas, y como era de esperarse me decidí por la más fácil, que es la que muestro a continuación.  No tengo fotos de todos los pasos intermedios porque la idea fue caminando a tientas, sin la seguridad que brinda el seguir un rumbo prefijado. Además, algunos pasos son obvios y no requieren explicación.

Este reductor se puede aplicar a muchos usos, no solo a un torno como el mío, de otra manera no valdría la pena publicarlo.

My "poor man's lathe" has a few flaws. Of course, if it were perfect it would not be "poor's" One is that, as it use as motor a hand drill, whose speed is variable but in too high values (1900-2500 rpm), sometimes does not help. Especially when the turning piece begins as a wood somewhat bulky and misshapen. If under these conditions it start to spin at 1900 rpm, can be a disaster because everything is shaken due to the imbalance.

This defect began to be annoying and dangerous, to the point that I was forced to stop other projects to build a speed reducer. Buying one is out of consideration, because they are not only expensive but also the work to adapt it to my needs would be so great as to build one. Evaluated alternatives, and as expected I chose the easier, which is what I show below. I don't have pictures of all the intermediate steps because the idea was groping, without the security provided by following a default course. Besides, some steps are obvious and require no explanation.

This reducer can be applied to many uses, not just one round like mine, otherwise not worth publishing.

Step 1: Nuevo Hogar Para El Taladro (new Home for the Drill)

El primer paso fue rescatar del fondo de un cajón un mandril en desuso. Por suerte lo pude encontrar. Lo llevé al lugar del torno donde podría ir fijado el reductor, y comprobé que era factible. Comencé por construir un nuevo soporte para el taladro, desplazado hacia atrás para que coincidiera la punta de su mandril con el tronco del mandril que mencioné antes.

The first step was to rescue from the bottom of a drawer a chuck into disuse. Luckily I could find it. I took him to the location where it could be secured on the lathe, and found that it was feasible. I started to build a new support for the drill, moved back to coincide the tip of its chuck whith the trunk of the chuck I mentioned earlier.

Step 2: Nueva Vida Para El Viejo Mandril (new Life for the Old Chuck)

Fui a la ferretería industrial del barrio y compré un tornillo de acero, 12 mm de diámetro, con rosca que atornilla en el mandril recuperado, y una tuerca. Gasté 5 pesos (U$S 1.25). Luego agujereé un trozo de madera dura para pasar el tornillo por su centro, y  torneé exteriormente la madera al diámetro del soporte del taladro. Finalmente ajusté el agujero lo mejor que pude al diámetro del tornillo, suplementándolo con tiras de chapa de aluminio que perteneció a un aerosol de desodorante. Con un poco de insistencia quedó bastante justo. Lo lubriqué con grasa de litio.  La tuerca que compré era demasiado alta, y la corté en dos partes para usar una como contratuerca, de manera que el tornillo quede firmemente asegurado al mandril, funcionando como eje.

I went to the industrial supply of the neighborhood and bought a steel bolt, 12 mm in diameter with threaded that screw in the recovered chuck, and a nut. I spent 5 pesos (U$S 1.25). Then bore a piece of hard wood to pass the screw through the center, and lathed the wood to the diameter of the drill support. Finally I adjusted the hole as best I could to the diameter of the screw, supplementing it with strips of aluminum sheets that belonged to a deodorant spray. With a little prodding was quite fair. I lubed it with lithium grease. The nut I bought was too high, and I cut it into two parts for use one as a counter nut, so that the screw is firmly secured to the mandrel, functioning as the axle.

Step 3: La Polea Grande (the Bigger Pulley)

De un trozo de MDF (fibrofácil) de 18 mm corté una polea en forma de corona circular. El agujero interior es un milímetro más grande que el diámetro del mandril, para que el cuerpo externo de este pueda girar libremente en el interior de la polea. Le atornillé en un costado un trozo de chapa de hierro con un agujero central del diámetro del tornillo-eje del mandril. Luego la aseguré fuertemente con la contratuerca al cuerpo interno del mandril. Le di dos manos de sellador hecho con cola vinílica y agua en partes iguales, para aumentar la duración del MDF.

From a piece of MDF (MDF) of 18 mm thickness I cut an annulus-shaped pulley. The inner hole is 1 mm larger than the diameter of the mandrel, so that its outer body can rotate freely inside the pulley. I screwed on one side a piece of iron sheet with a central hole, diameter of the screw-axis of the mandrel. Then tightly secured the assembling with the counter nut to the chuck body. I gave two coats of sealant made with white glue and water in equal parts, to increase the length of the MDF.

Step 4: La Polea Chica (the Smaller Pulley)

Como lo que necesito es reducir mucho la velocidad, cuanto más chica la polea, más efectiva. Así que opté por usar como tal el vástago de un tornillo. Pero resulta que este es sumamente resbaloso, así que tuve que cubrirlo con papel de lija, adherido con pegamento de látex (tipo Poxi-ran) 

As that I need is to greatly reduce the speed, the smaller the pulley, the more effective. So I chose to use as such the stem of a screw. But It turns out that this is extremely slippery, so I had to cover it with sand paper, attached with latex adhesive (Poxi-ran type)

Step 5: La Correa (the Belt)

La perrita de mi hijo estuvo un tiempo en casa, y entre otras cosas destruyó la traílla de nylon con la cual la paseaban. Pero quedó un trozo más o menos intacto, de longitud suficiente como para servirme de correa. Tomé la medida, la corté, y con un trozo de hierro calentado a la hornalla de gas derretí ambos extremos y los junté fuertemente.

My son's dog spent a time at home, destroying some things including the nylon leash with which they walked. But it was a length more or less intact, long enough to serve as belt. I took the measure, cut, and using a piece of iron heated to the gas burner, I melted both ends tightly them together.

Step 6: La Manivela (the Crank)

Para poder girar a mano el mandril, es conveniente agregarle una manivela. A tal efecto soldé en la cabeza del tornillo-eje un trozo de barra roscada para poder sujetar la manivela. Y para que esta se aferre al tornillo, soldé un exágono de chapa de hierro a una arandela. Luego corté un pequeño trozo de varilla de hierro, le hice un corte longitudinal en un extremo y separé en ángulo ambas partes antes de soldarla al exágono. En el otro extremo hice un agujerito de 5 mm de diámetro, el cual rosqué para ponerle un tornillo con contratuerca a efectos de colocarle una manijita giratoria. 

To hand rotate the mandrel, it should have a crank. To this purpose I soldered to the head of the screw-shaft a piece of threaded rod to hold the crank. And for this to hold on to the screw, soldered an hexagon of  iron sheet to a washer. Then I cut a small piece of iron dipstick, I made a longitudinal cut at one end and separated at an angle both sides before weld them to the hexagon. At the other end made a hole of 5 mm in diameter, which thread to put a screw nut for the purpose of putting on a little rotating handle.

Step 7: Conclusi�n (conclusion)

El reductor es indudablemente efectivo, pero tal vez para ciertas tareas resulte insuficiente. En ese caso me quedará el recurso de intercalar una etapa intermedia, es decir un par de poleas coaxiales y solidarias, una más grande que la otra, de manera de volver a reducir la velocidad. Mientras tanto lo usaré así como está. El video lo muestra en funcinamiento.

The reductor is certainly effective, but it may be insufficient for certain tasks. In this case I will have the recourse of intercalate an intermediate stage, ie a pair of coaxial joint pulleys, one larger than the other, so further reducing the speed. Meanwhile I'll use it as it is. The video shows it running.


¡¡Genial!!. ¡Siga con el excelente laburo !
¡Gracias, diente!
. I agree with PhilB, great work.
Thanks, Nacho, please read my response to Phil.
You have improvised from very little in tools and materials in very clever ways. Careful work is required to form a hex nut as you did on your crank handle and make it look as good as yours. I am surprised you were able to fuse the ends of the dog leash together well enough to hold during use. I am surprised the whole thing runs without vibration when supported by one bolt, one wooden bearing, and one relatively narrow collar around the wooden bearing. You do good work.
Thanks Phil, you are always so kind. <br><br>The hex nut was easy to do: the iron sheet is only iron, not steely, and thickness approx. 2 mm (0.075 inch); I fasten it with the vice over the nut and with the hammer gave it form. <br><br>The leash, I was lucky that was 100% synthetic material. <br><br>Regarding wood hubs, I learned to respect them since childhood, when my father did blacksmithing and mechanics at home. Threshers and harvesters that time had very few metal bearings, they were almost all wooden bushes, and lasted decades. Aluminum works too very well with steel, if you make an aluminum bush it can lasts many years. <br><br>The important thing in my reductor is the paralelism of the pulleys's axis, I was very lucky that they are well aligned without any needed correction from my part. <br><br>The negative side of the reductor is that if I want to use it, I must resign to traverse the axis of rotation, as I did for turning the top. It works always parallel.

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