I have just started designing a new low cost Fucking Machine. I have eliminated several costly components and generally simplified the design and construction.
The mechanical components are all inexpensive and very easy to assemble. The mechanical design uses inexpensive tubing for the ram and urethane skate wheels instead of the flanged bearings of the previous design. A few brackets will need to be made out angle metal but I will probably offer these ready made as well. A drive roller can be built out of available materials and I will probably offer a ready made one too.
I have eliminated the advanced features such as recording to audio. A stepper motor is used instead of a servo motor which eliminates one encoder and reduces the cost of the driver and power supply. I have a working prototype using a high quality Gecko driver but will be testing with less expensive Chinese components. The builder can choose cheaper or more expensive components to either make a less expensive unit or to insure the best and most reliable. I will be building several version to test performance and reliability of different component choices.
So far, the first prototype looks very promising, almost approaching the performance of the servo motor design.
My plan is to design a circuit board that allows the addition of elimination of various options so the builder can start out with a less expensive unit and add features over time if wanted. The following will be the minimal configuration:
Microcontroller board, stepper motor, motor controller, power supply, single potentiometer for position control, basic mechanical components with hard stops to limit ram withdrawal.
Additional options will include:
limit switches, encoder based roller controller similar to the current model, three knob speed, stroke and start position controls, LCD display to show operating parameters and possibly other data, color TFT display instead of LCD display, temperature sensor for motor protection, expansion capability for control with smartphones MIDI devices and addition to other sensors such as accelerometers, gyros and magnet sensors.
All options will be configurable and firmware will be updatable via USB connection. I estimate that a complete unit can be built to the minimum configuration for less than $400
Any comments are welcome.
a less expensive option sounds great since I always loved this in concept. The stepper motor you are thinking about, how much are we talking for the motor alone? My simple drive motor with speed control has probably cost me $150 for motor, power, bearing guides, couplings, etc.
it depends on the motor and driver chosen. my first test so far is with a random surplus NEMA 23 motor of unknown specifications using a Gecko G203v that cost about $165 delivered. i started with the Gecko because i know their stuff “rocks” it has the best low and high frequency motor driving capabilities. actually there is one of theirs (just released) that is even better and more expensive. buying a motor from Gecko would cost another $165. i have just ordered cheaper alternatives from Automation technology. i bought a driver that is middle of their line so i can experiment with different voltages and currents to see what the minimum requirement is. depending on power and speed required it should be possible to get by with a cheaper driver and motor maybe even their cheapest driver. the cheaper drivers have lower max voltage which limits high speed (microstepping) torque. i also bought one of their better motors to test with. i have a pile of surplus motors to also test with once i know what to expect from modern motors with known specs.
the power supply should be a simple transformer, bridge rectifier, filter capacitor unit with voltage regulation not required. i am also going to experiment with solid state power supplies because these can be gotten really cheap but i am not too hopeful for good performance from them.
the motor i ordered from Automation Tech has a 3/8″ shaft which i chose for greater strength. maybe it will be possible to use it without a jack shaft if you don’t mind replacing the motor more frequently due to bearing failure. my current prototype has a jack shaft with a sleeve bearing that is not difficult to make but could be avoided with a suitably strong motor. the jack shaft is a better design.
it will also be possible to convert a rotary/reciprocating fucking machine design to use a stepper and my controls instead. it would require limit switches and modification to the firmware but it is certainly possible.
Would the controller be Arduino based? Then a Pi for the network etc. A lot of power (and displays) for little money.
One of the biggest expenses of the original was the Geko driver and servo motor. Would a 23 stepper be powerful enough? Or is it a double stack 34 and are we back again to power v cost?
The whole plan is intriguing and I will follow with interest and hopefully modify my very basic in/out machine to something more satisfying.
The controller will be Arduino based using the same code I wrote for the current model without the audio decoding stuff. It runs fine on a Teensy 2 but a 3.1 costs just a couple dollars more and would be better for graphics and other options.
Tomorrow I will have the Automation Tech motor and driver to test. I bought a more expensive controller than is probably necessary because I want to see how much difference higher voltage makes. It might be possible to get by with a $69 driver and a $35 motor. A surplus motor can be used but they would probably cost as much as the Chinese one. I don’t think the old drivers would work well enough without advanced features like morphing from micro to full step. Still if someone wants a slow machine, almost anything would work.
I tested with a NEMA 23 of unknown specifications and it worked surprisingly well with the Gecko driver. Will know tomorrow how their NEMA 23 works. As I said previously, I got one that has a 3/8″ shaft which increased the cost a little. Someone on a tight budget could get by with a smaller one. Once I have a fully tested gigher end system I will be testing to see what the minimum tolerable configuration is.
I am very interested in any advanced features that others might be interested in programming such as an Iphone app to sync with music etc.