[iceblu3710]

Hey all, im starting to build my first cnc and have a few questions.

My friend from Idaho sent me a few 5804 ic's and on paper they sound great. 5v control and output can handle 36v and 1.2a but I have found a few issues with them.

Their input logic is very picky, it needs 100% ground or voltage to insure a stable stepping sequence and using pushbuttons with the classic 10k pull up resistor upon press/release theirs still a 10-20% error rate that causes the motor to shutter. The pc's paralell port at its somewhat wavering voltage cant seem to provide a stable 5ms pulse. Anyone use this ic before or have any ideas on a way to interface the two?

Im using a fast switching mosfett transistor and high current pullup diode so I can drive max 100v and 12a with only 2-300mv kickback. I have an el-cheepo 12v, 16ohm, 38step motor im testing with and even though each coil only draws 200ma (400ma each pole) the bugger gets damn hot. Is it because im just using a cheep stepper or what?

Last question is anybody have a favorite control program for windows (i can use win98 if its necicarry) befause using kcam and its port viewer I fell like tearing my hair out, every time i set one pin as output another one stops workking or stays high and never shuts off.

Well thanks for any advice!

[flyboy1015]

I can't comment on the 5804's, but I've seen the controller circuit that you're talking about. I had actually considered that one when looking for motor controllers.

I have used Mach3 for the software control side. It is pretty easy to use and seems to be the most recommend software by everyone that I've seen posting here at the zone. Unfortunately for me, I am using an older PC for my CNC computer and so I'm using turbocnc on it. My wife just won't let me take our desktop out to the garage for cnc use. I did use Mach3, though, when I was first testing my motor controllers and power supply. This, of course, was done on our desktop in the house. I recommend Mach3 if you're able to run XP, as it requires XP and there is a lot of helpful information on how to set up and use it.

Here's my machine: http://www.cnczone.com/forums/showthread.php?t=44336

Good luck.

[CountZero]

Regarding the pushbutton, you don't have any contact bounce in those? If you add a small capacitor over it you might get better response.

[iceblu3710]

Hey thanks for the info, im making a table similar to yours flyboy.

My pushbuttons were micro switches, spring armature contacts work better but they were only for testing so I just removed them and have my pic micro controller simulating a sequence of left/right/hold commands for a thought test of the setup. Theirs still a bit of an error rate on the step input though, is their suppose to be any circuitry between the ic and the parallel port?

I read flyboys page and you said that your steppers are driven at 36v/1A and their not hot at all makes me wonder why mine get toasty warm after 5min operation at 12v/500mA per phase, possibly because of my 18ohm coil impedance most good motors I have seen only have 2-5ohm.

Whats the prefered drive waveform anyways? Single-phase (wave drive), Two-phase, Half step?

[flyboy1015]

Iceblu,

I chose the Linistepper controllers because they take most of the heat instead of your motors taking it. You have to use a large heat sink with these controllers, but I think it's worth it. Mechanical things don't like heat so well, but transistors and other electronics are made to run warmer than a motor would. A chopper type controller would make motors hot. It all depends on what you're using. I'm also using half-step mode.

[iceblu3710]

Those lninisteppers are a good price, Im building everything ground up as cheep as possible so i can mill the components for version two. Plus its a good learning expereance. Im thinking of making two seperate machines, one for alluminum and one for pcb's as I use both on a weekly basis.

Can you reccomend some high resolution steppers?

Also what kind of bit is used in a pcb mill anyways? I have a 400xrp dremel but cant find a good bit.

Thanks

[iceblu3710]

Ahh i finally solved my flaky step issues.

Needed 10k pullup resistors on step and direction pins going to the paralell port and a .1uf cap for the ic cleaned up all the logic.

I definatly need to get real steppers cuz these no-name ones get to hot to touch only drawing .5A, when i get back to work (im in school right now) ill definatly be buying something close to 5v, 2.5A/phase, 3ohm, 3mH seen alot of 150-200oz/in for around $50

------------------------------------------------------------------------
Im going to buy these, good choice? Yes/No

EDIT: HobyCNC #23-305-DS8A 3A, 4.3v, 3.2mH, 305oz/in
------------------------------------------------------------------------

Any recomendations for a good pcb milling stepper? (needs high resolution obviously)

Ill post a full schematic and pictures once i get the new motors and everything running smoothly.

[flyboy1015]

I've seen a lot of good reviews regarding HobbyCNC anything. I got mine from www.Probotix.com. They were $39 each. So far, so good. Sounds like you've got a stepper translator up and working. Do you have any pictures of your circuit? I'm actually considering building either a smaller machine or a hotwire cnc. Since I spent all of my money on the big one, I'd have to have a much smaller budget. I have a couple of old printer steppers that I thought I'd use. Is that what you're having trouble with now?

[pminmo]

For milling pcb's you don't need a real strong motor. My recommendation for smaller machines is the Keling KL23H51-24-8B. At $29 it's a nice motor. If you want to roll your own drivers, there are a number of free circuits and pcb layouts on my website. http://PMinMO.com

[Gir]

For milling pcb's you don't need a real strong motor. My recommendation for smaller machines is the Keling KL23H51-24-8B. At $29 it's a nice motor. If you want to roll your own drivers, there are a number of free circuits and pcb layouts on my website. http://PMinMO.com

Thanks for the link. I was going to build one from scratch, but that makes it much easier

[iceblu3710]

Sorry for the terrible layout, I use multisim 10.1 but I dont know how to make a custom virtual IC so i had to use the dip16 package.

J2 - Power
J3 - Output
J4 - PC Input
J5 - Half-Step
J1 - One-Phase



J5 and J1 have 10k pullups even though I usually have them both to ground but Im testing other wave patterns.
J4 - I found i needed 10k pullups on the pc side because of the UNC chips flaky logic when tied directly to VDD or VSS
Im using 100v 12A fast mosfets with 100v 8A clamping diodes not the exact part numbers cust close enough so I can get a pcb layout.

The problem I found is if you bypass the UCN5804B's output becomes inverted so i had to use a logic inverter on each of the 4 output pins. I also have programmed by pic 18f4550 beast up to those mosfets and it can drive them without problems so I might end up using just one pic with 12 outputs and 9 inputs because that way theirs no need to use the ucn5804b and an inverter. Another alternative method is a CMOS binary counter with reverse couppled to a binary to decimal decoder to drive the mosfets but once again two IC's.

Anyone use a pic for control? Ill be looking for a timing control so I dont exceed my motors speed. My current ms accuracy is only accurate to +-2ms

[sansbury]

I just posted a long piece on my experience with PCB milling in another thread here:

http://www.cnczone.com/forums/showpo...12&postcount=5

10Bull's site was one of the better resources for me to get my first boards cut.