Nick писал(а):А там реально нужны такие мощные движки???
К сожалению, не могу ответить, т.к. сталкиваюсь с этим первый раз. Вот что пишет автор станка (правда, в 2008 году):
1. first choice in motor is a geared stepper motor from Oriental Motor Corporation available as a simple secure on-line purchase at around US$250.
It is the Vexta-Step type PK296A2A-SG7.2 :
Geared motor
Most MechMate builders use this motor and are happy with it. (has some backlash). It works well with Geckdrives 201,202,203,250,251,540 However, it is an expensive motor, and difficult to obtain outside the USA. The equivalent motor in Europe is the Oriental Motor PK296AE-SG7.2
2. Second choice is to use an un-geared Nema34 size stepper motor directly driving the pinion on the rack. Have past personal experience with Oriental Motor Vexta-Step type PK299-01AA motors ($205). Less expensive than the first choice geared motors, but less shaft torque and a slightly rough cut quality. Still produces a very passable CNC router. The smallish price difference does not make an un-geared Oriental Motor attractive, unless you want to start out with a well-known motor to add a non-backlash belt reduction later. If you want to go this route, the Oriental Motor Vexta-Step type PK299-F4.5A is probably a better choice than the PK299-01AA that I used before.
Un-geared (direct) motor
3. Third choice is still to use an un-geared Nema34 size stepper motor directly driving the pinion on the rack, but to go for something much less expensive than the premium "Oriental Motor" brand. MotionKing 34HS9801 is being used happily and can be imported direct from China. The price over there, without shipping/tax charges is under $60. One of these inexpensive motors, with a belt reduction added at a later stage, will rival the performance of the "first choice" geared Oriental Motors mentioned right at the top. Even before adding belt reductions, you will have an income producing CNC router. You will be spending a little more time on sanding the slightly rough edges of your cuts though.
What to look for when selecting a motor:
1. Only consider a square body motor - the round body motors are older technology with a lot less torque.
2. Use at least a Nema34 size, meaning that the square body is 85x85mm [3.4x3.4"]. Smaller sizes will be under-powered.
3. Do not be tempted to use bigger than Nema34 motors - they will not fit the standard mountings provided for in the design. Besides, bigger motors bring other problems.
4. Nema34 motors are available in different lengths, depending on whether the rotor magnetics are single, double or triple stacked. For geared (or beltdrive) motors, a single stack (motor length about 66mm [2.6"]) is enough. When used un-geared, you will need a double-stacked motor at about 96mm [3.78"] long. Avoid motors much longer than this - see point 3 above.
5. For the MechMate mechanical design, the motor shaft must be at least 12mm [0.5"] in diameter to carry the spring load and not bigger than 14mm so that a small pinion gear can still be fitted. The shafts must be at least 32mm long to reach the rack, but not longer than 40mm otherwise they will collide with the rail supports.
6. The best wiring configuration for our router driving application is "half-coil". (this gives the most torque at high speed while keeping the motor temperature within limits). To wire a motor half-coil, it must have 6 or 8 lead wires.
7. If you want the motor to be compatible with a certain range of drives, the motor inductance must match. For Geckodrives, the inductance must typically be somewhere between 1.5 and 6mH. (The Gecko 250/540 wants around 3mH). Very low inductance motors cannot be driven properly by Gecko's, while very high inductance motors need very high voltage drives that are not easy to obtain.
8. If looking at a motor already integrated with a gearbox, watch out for the backlash. The "first option" geared motor above has an acceptable backlash for general board cutting and cabinet making work. It will not pass for fine precision clock-making (but then you shouldn't be looking at a MechMate anyway). Belt reductions give the fine resolution without backlash.
9. Consider getting motors with rear shaft extensions, so that encoders could be fitted. Geckodrive has a drive under development that will pull more power out of a stepper motor if it has an encoder (ala servo motor). Not a new technology (Oriental Motor has the Alpha-Step series, for example), but there is a talk of a retro-fittable feedback /drive system at an economical price, within a year or so. . . .
10. Bear in mind that geared motors have a higher detent torque. ie. they can hold a higher load when power is removed. If you are going to have a very unbalanced z-axis, a geared motor might be able to hold it up when you switch off the power.
В общем, я так понял, что это должен быть двигатель с квадратным корпусом, Nema 34, если с редуктором/ременной передачей, то длиной около 66мм достаточно, если без, то нужен мотор с 2мя валами (???), длиной около 96 мм; вал мотора от 12 до 14мм в диаметре, длина вала - 32-40 мм, лучше с 6-8 проводами, чтобы возможно было подключить половину катушек (???), фазной индуктивностью 1,5-6mH. Поправьте, если я запутался в понятиях. За последние два дня я прочитал по этой тематике столько, что голову просто разрывает.
Уже присматриваюсь к драйверам Leadshine и USBcnc-контроллеру и управляющей программе. Как писал arelav в теме о чертежах mechmate, вес башни получается около 70 кг, может поэтому такая мощность двигателей? Подскажите, может, правда поменьше взять, а то наломаю я тут дров
, а вернее, фанеры...
Я услышал и забыл, я увидел и запомнил, я сделал сам и понял...
