This post follows from my previous blog “What is the best way to create open source hardware?”
Let’s go into the details of the stated objective:
AccessI will use an example: Retrofitting; It is considered by far the best alternative if you want a low cost CNC machine, you buy an old machine, hopefully it’s not in too bad of a shape, you clean it, exchange wore components and slap on new motors and a controller. This all sounds good until you take into consideration my four points. Access, in the State is where this point makes less sense, we are surrounded by machines and you can pick them off eBay for almost nothing, the only problem is freight and even that is not a problem in a country with the lower fuel and transportation cost of any industrialized nation. Ok there are some bizarre exceptions to the lowest fuel cost but these are none significant manufacturing countries like Venezuela and Kuwait. In other parts of the world, there are no old machines to be retrofitted and moving them around is very costly.
Control
Capabilities
Cost
Control; you can do some things to existing machine like improve their performances. According to a recent presentation by Fanucon retrofitting machine’s, most machine can improve ~20%+ with a new controller and motors. You can increase the accuracy of the scales and mount fancier linear slides and there is more. Soon the costs starts to match those of a new machine but you are still limited to the original design of the machine. In terms of capabilities it is similar, say you have a new part no one has made before or a new process you want to implement, many times it is hard to meet these new requirements with traditional machines. What if you need more reach, overhand or rpms and your only option is to order a custom machine?
Cost is also an issue, according to Fanuc’s presentation most retrofit cost 1/3 to 2/3 of the original machine, and among the advantages sited are that you don’t have to move, transport and rebase a new machine, sounds reasonable. They also quoted that retrofits can be more efficient up to 55% energy saving, this I found to be impressive.
So is it really that much better, to buy an old machine, freight it around and then pay Fanuc for an expensive retrofit?
Now lets talk about the options. Open source controls? What if you could have a PC base Linux system running your machine? With a touch screen! EMC is a good choice, which is what I have been using, they have an very active community, hundreds of working CNC retrofits and it doesn’t cost you anything. You still have to put together the hardware, controller, motors and so on, but at least on this front you have a choice.
I think significant gains can be achieved in open source hardware by providing plans for a EMCbase controller with all the hardware included. You simply change the power/speed ratings for the motors, some control parameters and sensor/auxiliary features. This will take out all the guesswork out of wiring and buying components and you may even get pre-made kits form new suppliers that do not exist today. Or do they already exist?
I want to hear your comments on this as well.
A 600$ Gataway machine runs EMC and the machine
Our I/O board and its connections to the machine and the PC
Electronics cabinate, power and motion control components. Source of most of AutomationDirect
View of the machine from behind
View form the the front. This was the firt time the machine some G-code!
