the best

[mocnc]

Hi guys, its been a long time since I have been here............had a bit of a scare in my life was unable to do much for a while. Before I had my scare I manage to put together a wood router cnc and also built a 4th axis chuck to hold any work items (like a lathe). Since its been a long time, almost 2 years now I have lost touch on what is the best way to go. My cnc has a work area of 15" x 28". I wanted to work with a 4axis system to do thinks like pool cues and cnc round stock etc. Now here is the problem......polar or unpolar, which driver system is the best? What does everyone else use? programs? turbo cnc?? desk cnc?? How about the cad/cams? One last question, now a days the parallal ports are dying off.....I believe lap tops don't come with them any more, and I think the desk tops also are stop making them standard. Is there a usb driver instead of the parallel port? What or if there is, the new technology? What is everyone using or suggest? I remember from the past that this board was always helpful, I hope it still is. I know some of you may say look for yourself....do the work yourself.....I am...I am trying, but its, well I am not the same as I was a few years ago. So any help would be greatly appreciated. Thank you

[hemsworthlad]

Hi Mo,
Welcome back, life's can flip on a dime I know all to well so it's nice to hear your bouncing back. I'll try to help but please dont take my suggestions as gospil and others will have very differant opinions i'm sure but these work for me and the machines I build.

Bi-polar parallel tends to be the popular choice due to providing better torque and speed balance.
Drive's well.!! This is where the shouting from others may start.? IMO and thru experience you cant beat Gecko drives and the real peach from Gecko is the G540.
It comes with 4 drives with a max 3.5a motor range and accepts between 18-50Vdc, it's incorporates midband resonance damping which is a nice and usefull feature, autostandby current limiting meaning the motors stay cooler like stood still another very nice feature that works, It's very well protected with optoisolation and short circuit protection built in.
It has a breakout board built into it with charge pump and plus all the usual inputs for things like limits etc along with 2 normal outputs plus a anolog output that provides 0-10v signal for controlling things like VFD's or spindle speed controllers.
All this in one very neat and small package and really for a quality system it cant be beat for the price.

RE USB well mainly unfortunatly it's still mainly PP(parallel port) based but there are some alternatives if you really need to use USB. First normally you can NOT just use a USB-PP converter due to the way usb works, I say normally because I think you can if you use EMC and some home made type drive using things like Arduino's but i wont and wouldn't go there if your not a techie type.!
To run from a USB port you need an external pulse generator that takes the information from contol software like Mach3 and then generates the pulse's for the drives. There are several differant manufactures and they can be pricey, I use a Laptop and have the smooth stepper which tends to be the most popular if you use Mach3 which i believe is the only control software it works with and it cost me $160 but it's one of the best things i've bought for my machine and here why.
It's basicly a 2 x PP's on super strong steroids, the best speed the PP/Mach combination can muster with a superfast computer is 100Khz where has the SS can reach the dizzy heights of 4Mhz.! In practice thou you dont use this speed(but it's there if needed) but basicly what it does do is give you a very very smooth pulse signal which then gives very smooth and improved stepper performance.
The other very nice feature is that you dont need a powerfull computer or laptop to run Mach because it takes a massive work load away from Mach essentially leaving Mach to just deal with G-code interpritation and it deals with the hard work of generating pulse's.
Another nice feature is the extra Inputs/outputs because the SS bascily 2 x PP's in one.
IMO if you need USB control then it's worth the money and if like me you need a laptop the it's almost the only option.

Software well thats a very personal choice and budget dependant as well as work dependant. I use Bobcad V23 but I wouldn't recommend it to anyone due to the poor customer service and the very crapy way it works.
Vectric products VcarvePro, Cut2D, Aspire are all very nice and range in abilty's and price to suit most users. It really will depend on your usage and budget but there are some really nice bits of software that dont cost the earth if your prepared to take a steeper learning curve software like Cambam is quit capable and not overly expensive.
Look around and there's something to suit every pocket and abilty.

Hope this helps.
Dean.

[JD_Mortal]

Although LPT/PP are a dieing trend... There is still support for them, VIA PCI cards and even external cards. POS and many corperate old computer printers still depend on LPT/PP. (Though, the external cards are USB, and the issue with USB external cards is, again, the delays and cut-off interruptions due to sharing USB devices. All keyboards and mice and camera's that are built-in to a computer are USB devices, even though they are wired directly in most instances.)

I suspect, as mentioned above, that the "arduino" crowd (Actually all micro-controller crowds, PIC, ARM, ARDUINO, etc...), will soon have a cheap USB alternative that is plug-and-play for USB. Until then... You should just focus on the LPT/PP, interface.

If you are tech-savvy... And know about microcontrollers stated above...

What you are looking for is some "RepRap" or "MakerBot" or any stepper-control programs that accept raw g-code as instructions. EG, you will not be dependant on programs like Mach-3. You will have to make adjustments within the code itself, or use a code-scriptor which creates the code using your settings. (Settings would be for delay-times, milling speeds, axis-setup, stops, limits, etc...) Again, that is only for the tech-savvy, who know how to use that stuff. Essentially, you just load the code, and run it. Thus, no computer dependence. Code can be spewed from USB, or run from a flash-memory card like SD, Micro-SD, Flash, etc... It would talk directly to the driver-boards, so no PP/LPT interface would be needed.

Ironically, many drivers and even a few LPT/PP interface cards use an "Arduino-chip", aka: Atmel Tiny or Mega, to handle buffers and pulses and modify amp/volts/signals. But that is beyond anything you actually needed to know.

As for the motors, I prefer bipolar, due to the fact that they have less dead-mass. Unipolar have one coil for each direction, thus, 50% of the motor-weight is dead-weight. Eg, it has half the coil windings are useless. That translates into less speed and power, at the same weight of any unipolar motor. However, the advantage of bipolar, besides less complex drivers, is the heat-dissipation advantage-potential. (I say potential, because if you drive them to be equal to a unipolar, they will burn-out and create double heat.) The fact that you only use half a coil winding for forward, and half for reverse, allows each unused coil to dissipate heat while it is unused, while switching direction. If you run it at it's half-speed/half-torque value.

Unipolar = 2 shared coil-pairs, (2 forward, 2-backwards, wound on the same 2 poles. Half winding is forward, half is backward on each pole.)
A/B = Winding, ( and ) = pole
8-wire winding setup: (AFWD+,AFWD-,AREV-,AREV+),(BFWD+,BFWD-,BREV-,BREV+)

A/B/C/D = Winding, ( and ) = pole, [+/-] = fwd, [-/+] = rev.
Bipolar = 2 isolated coil-pairs, (2 forward/backward, you have to change polarity to change direction. Coil winding is on the full length of each pole.)
8-wire winding setup: For double-torque/speed (A1+/-,A1-/+,A2+/-,A2-/+),(B1+/-,B1-/+,B2+/-,B2-/+) or for double-precision (A+/-,A-/+),(B+/-,B-/+),(C+/-,C-/+),(D+/-,D-/+)
4-wire winding setup: Most motors (A+/-,A-/+),(B+/-,B-/+)

The other advantage is, if they have the 8-wire setup... You can turn a unipolar into a bipolar, by simply reversing one pair of wires, and linking them as series or parallel to each other. (Though, you must be SURE they are the correct pairs and directions reversed.)

Bipolar seems to be the "new standard", as that is all I see all over. More support, better production, widely available, easy to replace when broken. I say, go with bipolar.