Pablo,

I am sure you won't forget, but I am not seeing a Cooling Fan for under/around the gecko's.

The layout you are using is the 'standard' Mechmate layout, I use the same.
Except that I could place all Gecko's in one line.
Placing them in one line makes it a tad easer for wiring.

I did run the power of the gecko's all on the left site, and the control lines to the gecko a smutch is possible to the right. Either crossing power and control lines, or in parallel at some distance to minimize cross-over signals from power to control.

Some additional detail. My control lines from Bob To Gecko are shielded, but not connected to GND (GND of the BoB that is). Because the BoB Doesn't have a easy place to add shielding for control cables, at least with my 122 type BoB. SO far, I have zero issues, but I don't have a spindle which are more electrical noisy.

Lastly, and I am sure you know... the Bob + control cables will not get grounded to the case, just through the parallel cable of the PC. The same goes for the power supply of the BoB that will not get grounded to the Chassis.

No, I did not forgot, but Im planning going fanless for the geckos, each one will have a piece of 10mm aluminum bolted to them (photo) and this piece will be bolted to a 25mm chunk of alu, IMHO there is plenty of dissipation there to go fanless, if its not enough I would like to read why.

http://a.imageshack.us/img814/8679/img1105a.jpg

I can put all the geckos in one line, but the space between them is pretty small, so I went for two rows, one alternative to this layout would be to put the top row with the connectors to the opposite side to allow easy connection.

Regarding control lines, what I did when I made my 1st control box for another cnc router was to braid them, same concept as ethernet cable.

And finally regarding BOB ground, yes, there are big notes on the pmdx125 manual about what to do and what not to do regarding gnds

Thanks for the comments.

Pablo,

Glad you are up to speed there, expected... just wanted to mention...

About the alu block, it's been a been long time since I had to do any calculations on (mainly power supplies), but her is my theory :)

The block will cool as long as it's cold, but as soon the block get's warm they cannot dissipate the heat because the surface area is fairly small compared to there size.
Even if you put a fan on it, it will take a lot more time untill the heat is removed from the alu block once it's there, I don't know anymore how well Aluminium transports heat...

That said, I just used a 6mm alu plate with a fan underneath and the works like a charm.
The gecko's don't get to warm because the operate mostly in the digital domain,
but I do noticed they need some cooling.

Ries

Bad heat conductors do what you mention, thats why there are cooking pans made of thick cast iron, they keep the heat very well.

AFAIK aluminum is one of the best heat conductors and in the same price range only surpassed by copper and silver. Regarding the Alu 25mm bars I can help the heat spreading by milling slots on them, less alu more dissipation surface, a good treadeoff methinks... just an idea :)


Pablo

pablo,

if you make a tube out of them, then you can put one of these micro fan's in the hole ;)
I am very rusty on these subject.... Hope it's doesn't bug you!

Pablo,
The large mass of alu will give you a large thermal mass. This means that when you couple heat to it it will take longer to heat up. The problem is as Ries mentioned is that once it is hot, it is the surface area that will transfer the heat to the ambient air. That is why heatsinks always have fins, or pins, or some surface treatment like that that will increase surface area to help couple the heat to the ambient air. Airflow, from a fan or whatever, will aid in the heat transfer

Pablo, heat is energy & it can't be created nor destroy, since we don't convert this waste heat to other form of useful energy, we will have to dissipate or dump them into the atmosphere.
Since the heat source is encased within the control box heat will have to pass on to the control box in order to dump into the atmosphere.
Without fan you can only rely on natural air convection current inside the box, conduction through physical metal contact and radiation to "pass-on" the heat to the control box external casing & then "pass-on" to the atmosphere.

Thicker AL doesn't dissipate faster, it only store more heat like a bigger reservoir, to dissipate faster, you need more contact surface. and ideal heat sink is one that is zero thickness with huge surface area. hence you see fins on "real" heat sink. Milling your bar does increase the total surface area.

Also remember that paint is not a good heat conductor so it does contribute heat insulation effect. Having a fan increases the convection heat transfer drastically.

Another note, heat is electronics worst enermy... adding a fan helps... a lot... adding one isn't much trouble to you, I'm sure.

If you must do fanless, alternative is to have the heatsink pertruding outside of the control box or use a heat pipe (just a piece of solid metal such as al or cu)to pipe the heat to an external heat sink. It can just dump the heat to the atmosphere without going through the air within the control box & the control box.

OK OK :) a good gentleman recognizes when he is wrong :) will mill slots on the alu bar but also will add a fan below them. Thanks for the input!

Pablo,

1/4" thick aluminum is sufficient, but I use 1" aluminum at my test bench. The Geckodrive G203v are usually used with motors that can pull 4.5A and they hardly get warmer than room temperature. The aluminum bar is about 16" long X 3.5" high (I'm away from the test bench, so I can't measure it). It was just a piece of aluminum that I had on hand.

Thinner is better and fins are best, but unless you really pull some amps through your motors, I don't think you'll have any heat problems.

But you do use a fan or not Mike?

On my last tour through the scrap yard I saw some aluminum grate. Holes were about 1cm x 3cm with intervening web approximately 6mm. I wondered if that was thermally connected to outside of case if it would keep inside of case down to ambient?

Pablo,

I use a fan, my Gecko's do get a bit warm (more then hand warm) under some circumstances. I am not sure what altitude you are (I am at 2400 meters) there is somewhat less air so they tend to get a bit warmer, and since I am in Ecuador a average tempreature sometimes in the workshop of 22-26 doesn't always help well.
To be honest, better save then sorry and specially in the beginning there are other things to really worry about then heat of the Gecko's, so I added the fan on the gecko's, my 110V fan did cost me 6USD I believe.

Ken a heatpipe is usually used to transfer heat of much higher temperature, for power amplifiers for example. They are liquide filled pipes with metal wires to make optimum contact to surface area. heat is transferred because the liquid inside starts to evaporate and condensate other other place and thus transfer heat. They are not simple pipes!!

Ries,
I recon the wiki isn't complete;). To my interpretation, heat pipe/thermosyphon can be just simple pipes/rods, any media dedicate to facilitate heat transfer from one point to another is considered as heat pipe. having fluid doing the job is one way & a solid or hollow metal of high thermal conductivity is another, even gas are used (air-conditioner).
With liquid & gas media, the medium "carry" the heat; with solid, heat conducts from higher temp to lower temp.
our coolant pipe is a heat pipe & for computer cooling, the solid copper rod connecting to an external radiator acts as heat pipe too.
Eventually, heat are dumped into the atmosphere air via convection+conduction. with a fan blowing, we can use smaller surface are then natural convection required. Spraying the heat sink black will help in the radiation department (like car radiator).

Pablo,

I don't use a fan, but the normal temperature of my test bench work area is 75F. The G203v is rated to 70C, but should be kept to 50C for best life expectancy.

As others have said, a thinner piece of aluminum (1/4") with a fan will remove heat faster than a thick piece of aluminum with or without a fan.

If the baseplate of the G203v gets to 50C, it's time to rethink the heatsink. The same can be said for the transformer and other electrical devices. The toroidal transformer that I use rarely gets more than ten degrees warmer than ambient, but a standard transformer, rated exactly the same, is too hot to touch under the same load. Because of that, I don't use standard transformers. That's another reason that I tend to underrate the power supply voltage from the formula (32 X SQRT(Inductance)) by about 15% to 25%. I prefer the stepper motors to only get moderately warm, not hot.

The nice thing about building your own controller is that you can easily modify anything that needs modification. If you were building controllers for resale, you would want to find the "perfect" heatsink for your application, but as the designer of a single unit, you can change the heatsink anytime that you desire with minimal cost.

please upload oringer file in Solidworks because i couldnt edit EAMS files , thanks

What file are you referring to?

check this post Karl: http://www.mechmate.com/forums/showt...0&postcount=29

Here is a "non" update, antiupdate you may call it :)

My progress with the new shop is ZERO, after almost a year of purchasing the lot, and many promises that the permits would be ready, they are not ready, so I don't even moved a brick from the lot, sad as it sounds the only progress was the removal of the phone box in the middle of the lot...

The person who was doing the permit with the city no longer answers my calls, Im frustrated to say the less, not only with him but with the city too, they put so many obstacles its insane, opening a new shop in the Federal District is becoming more difficult day by day...

Anyway, Im still around, Im still interested in making my MM, but I still dont know WHEN, in the meantime I keep learning, and thats positive!


Pablo

In the US I called it "Red tape". The Govt has an endless supply of it. Seems they have nothing better to do than hinder progress. But don't pay them for this or that, and they will be right there to let you know... :rolleyes:

Perhaps you need an expert to guide you through the jungle. In some countries I guess this amounts to a bribe. In the U.S. at the last resort you hire a lawyer which feels like blackmail. It is a specialized skill set though, so biblically, Matthew 10:10 says "A workman is worthy of his hire". So long as they don't bleed you dry, you at least get your shop.
Good luck!

The "expert" does not return my calls, this guy is not worth a dime :mad: so now I only talk to the architect who referred him to me, anyway one way or another I will have a new place... the big question is when :)

Looks like official the world around love to make their present felt by wholesaling red tapes... No exception in my place too...

A few quotes:

A bureaucrat is someone who can invent more problems he can actually solve himself.

The interpretation of the rules and procedures should normally be linked to some level of intelligence.

Novato pero no tanto
 

Me gustaria contactarme ,ya construi 2 maquinas cnc pero pequeñas una la joe 2006 tal vez la viste por la web,me gustaria saber si las partes cortadas laser y el plegado son de aqui de Argentina ,exelente el trabajo de solid un abrazo y desde ya gracias

Si, son cortadas aca, estoy de vacaciones ahora, mandame otro mensaje mas cerca de fin de mes. Saludos

Pablo te molesto de nuevo, me podrias dar una mano con esta exelente maquina.Si te sirve tengo bastante experiencia en electronica ,tal vez te sirve,gracias

Hola, te aclaro que yo aun no tengo la maquina armada, que es lo que necesitas?

Las partes me las cortaron aca en el gran buenos aires, pero seguro por alla tambien debe haber quien las corte. Motores podes comprar en www.lineartec.com.ar o www.varitel.com.ar, o si queres los motionking que muchos usan en este foro tenes un proveedor tambien. Drivers y placa interfase yo los traje de USA, los compre en www.pmdx.com y las poleas para la reduccion tambien, pero si buscas aca seguro encontras, pinon y cremallera conseguis en www.newrank.com.ar y las ruedas en V a mi me las hacen en un torno CNC como favor asi que no tuve que preocuparme por eso.
En cuanto al hierro estructural, pedi varias cotizaciones porque la variacion de precios es importante.

Luego es ponerle el hombro e ir armando todo de a poco, yo hasta no tener lugar no puedo hacer nada, ya tengo absolutamente todo lo necesario para armar la maquina, solo me falta espacio.

Saludos

Te agradezco muchisimo la ayuda,ya tengo los motores drivers,y aqui cortan por chorro de agua ,y comenzaria por el accesorio para amoladora y los doble rulemanes en v,si me puedes enviar el archivo de corte por torno cnc de los rulemanes,los podria fabricar en la universidad o de un amigo que tiene torno cnc. Me parece que eso es lo primero piñon y cremalleras aqui tb hay ,se me ocurria ponerle o correa dentada o cadena y piñon,pues son mas silenciosos y router tengo maquita de los grandes,ya construi 2 maquinas y estan funcionando las dos una la construi con mi primer maquina y fue todo mas censillo,esta me parece una de las mejores que pude ver en internet.

no tengo el codigo de las ruedas, yo les di los planos y ellos se ocupan del resto, cualquier persona que sepa manejar un torno cnc te lo hace en 5 minutos al codigo

Because my new place permits never materialized I will have to delay my build, this time I don't know for how long, so I'm selling some parts, maybe someone else here in Argentina can use them to build faster. This does not mean I'm leaving, I'll keep learning here, the time will come!

Now in spanish:

Tengo estas partes para vender, las mismas estan a lo que me costaron, incluso las que compre en USA estan a costo de USA:

Reducciones Castone, partes laser (4 pares) $370
Bujes roscados 1/4" para las reducciones (16x) $100
Rulemanes para reduccion (8x): $150
Poleas y correas (SDP/SI de USA) (4 kits) $540 (Drive Pulley: A 6A 3-15DF03716 / Driven Pulley: A 6A 3-45NF03716 / Belt: A 6R 3-054037 )
Motores MotionKing 9802 (c/u) $492
Kit Laser MechMate completo $1500 (ver fotos en posts anteriores)

Los precios estan en pesos (divide by 4 for USD) y puedo hacer factura A si les sirve, hay que adicionar el IVA (21%) en ese caso.

Puedo enviar a todo el pais por expreso previo deposito bancario

Me pueden contactar a: http://dl.dropbox.com/u/3624504/pablou.png

Gracias!


Pablo

pablo lamento tu venta. esto es un gran paso hacia atras. las partes laser estan completas con el skate?

Nada que lamentar, se hace lo que se puede y hay veces, como esta, en que la solucion no depende de uno sino de algun burocrata... Probablemente me termine haciendo un router un poco mas pequeño para el lugar actual que tengo y mas adelante encarare el mechmate cuando disponga de lugar.

Si, todo el kit completo, fijate hay fotos en mensajes de hace unos meses atras.