Linistepper update

[posix]

Well folks I have completed my drivers, the knee-mill and I can tell you that linistepper and dremel can dig into a piece of pine like hot knife through butter!

I just did some engraving on the back piece of a pcb and it works nice. I even made a mistake of inputting -2mm rather than -0.2mm and it just dug into the pcb and started writing.

So I can conclusively say that linistepper with 1.2A step-syn motors works like a charm!

I'm using a 12v ATX PSU and an additional $5 12v computer case fan is blowing across the linistepper to provide some fresh air to those alu coolers.

[James Newton]

Pictures? Please? Pretty please?

[posix]

Sorry, my fault.

The first pic shows my "machine" and the second shows the drivers, breakout board and the fan.

I have 2 videos of the whole rig in action, how do I upload them when it gives me "unknown file type"?

P.S. sorry for "pro-quality" images, It's only a nokia phone camera.
P.P.S. oh and btw you can clearly see my patent-pending "drawer-slide-mechanism" in the first pic.

[posix]

Oh and one more thing, I have updated the eagle files somewhat to re-trace everything and now hopefully there are only one or two tight spots all other traces have plenty of room either side for home-brew pcb making

[pminmo]

Posix, James
I guess the first question is the status of Posix version of the the Linistepper? I'll offer to put up the details on my website for the DIY'er, if you feel it would be appropriate.

[James Newton]

From the picture of the controllers, it is hard to see, but there are for sure no heat sinks on the transistors to the far right, and I'm not sure there are any on the others. If you run that in anything other than full or half step modes, with any sort of load at all, you are going to burn out your power transistors, fan or no. What modes are you running in? Are you checking the temp on those after a prolonged run? Do you see a significate difference between the modes in terms of heat and precision?

Can I ask you a favor? Would you add piclist.com to the board layout by the linistepper name? If you do that, I'll host the files on the site, with full credit to Posix and link here, for people who want to make thier own PCBs and anyone else can put the files up without offending me. I would really appreciate that, just credit where due, right?

Please keep in mind, (he says, putting on his sales hat) the original PCBs for the units are available for $35 for a set of 3 from piclist.com. I do realize some people just love to make PCBs, but you can't beat just over $11 each for professional, double sided, plated through holes, silkscreened, solder masked PCBs. And at $25 each for a set of three kits of all the parts, including the PIC, preprogrammed, only someone with a good junkbox is going to want to do it themselves.

[James Newton]

I forgot to say... Nice looking mill there... Is that your design or a clean execution of someone elses?

[posix]

Originally Posted by James Newton From the picture of the controllers, it is hard to see, but there are for sure no heat sinks on the transistors to the far right, and I'm not sure there are any on the others.

That is right, there are no heatsinks on the board nearest to the fan. I was too eager to have everything up and running and the fan is keeping everything in check for me at the moment.

If you run that in anything other than full or half step modes, with any sort of load at all, you are going to burn out your power transistors, fan or no.

I only ever ran the machine for 2-3 minutes at a time and then cut the power alltogether. I'm still at the halfway point of a very steep learning curve

What modes are you running in?

While I was building linisteppers I was going through 200, 400, 1200 and 2400. I am now at a constant 1200. But that may change when I have ironed out some other things (lack of volts on my psu being the first issue to tackle)

Are you checking the temp on those after a prolonged run?

No as there are no prolonged runs yet to speak of. But I surely will once I'm confident my mechanical side of things warrants that. As things are my machine is not ready yet for any substantial jobs to be thrown at it.

Do you see a significate difference between the modes in terms of heat and precision?

Oh well that is THE question. I can tell you that at 200 steps you get your standard driver with all the buzzing and vibrations of any other full step driver. 400 improves somewhat and brings a smile to a newbie.

1200 is where the action begins and a big grin materialises on anyones face who is used to steppers buzzing and jumping and vibrating. If anyone say the gecko video of mariss drawing that spiral will immediately know what I'm talking about. As I said I'd love to upload the video so you can hear linisteppers in action but it just won't let me.

Can I ask you a favor? Would you add piclist.com to the board layout by the linistepper name? If you do that, I'll host the files on the site, with full credit to Posix and link here, for people who want to make thier own PCBs and anyone else can put the files up without offending me. I would really appreciate that, just credit where due, right?

Well, it allready says linistepper v. 2005 on the board so it's clear where the layout stems from but no problem, I'll add piclist.com to it as well if I manage to find enough space. Ok.

Please keep in mind, (he says, putting on his sales hat) the original PCBs for the units are available for $35 for a set of 3 from piclist.com. I do realize some people just love to make PCBs, but you can't beat just over $11 each for professional, double sided, plated through holes, silkscreened, solder masked PCBs. And at $25 each for a set of three kits of all the parts, including the PIC, preprogrammed, only someone with a good junkbox is going to want to do it themselves.

Well, this is something I've been saying right from the start. The linistepper really is good value for money, whether you build it or buy it from piclist.com. The reason I didn't buy mine from james are twofold, first they would've gotten "lost in the post" and second educational value. For someone who burns their fingers on a soldering iron regularly then, by all means, purchase a finished quality item from james at piclist.

[posix]

Originally Posted by James Newton I forgot to say... Nice looking mill there... Is that your design or a clean execution of someone elses?

It is mine from tip to toe, actually. Not a single idea off the internet went into that design, but then how many ways are there to make a sliding table? Not that many. The linistepper is the only element I drew on from somebody else, but even linistepper was so close to what I allready had made myself, just with bc337s thrown in between pic and tips. And my software was doing full and half stepping only whereas linistepper programming is much much bigger than mine. Which reminds me, I was going to do some analysis of linistepper assembly to try and cut the number of lines of code.

Also, how hard would it be to convert linistepper to use l298 instead of tip122? I'm thinking chopper driven by linistepper logic. Now that would be a hit!

[James Newton]

I guess if it says linistepper on the PCB, then anyone who knows how to use google will find piclist.com, but if you have the chance.. it would be nice.

Can you email all the files to me (jamesnewton al piclist d0t c0rm) or ftp them to ftp://ftp.piclist.com/in including the videos, board files, photos, etc? I'll put them up on the site and make them available for download.

Do you have plans to publish the plans for the mill? What sort of repeatibility and accuracy are you getting?

The chopper version would require more of a design change than just the drivers. The method of sensing and regulating the current would be very different. Best to design a different controller, and there are others around that do that sort of thing.

[posix]

Could I have caught a bug in software?

Yesterday was the first time I played a bit with 2400 steps (mode 11) per unit and 17 units per second (40800 pulses/sec, the max it will spin without stalling at this voltage) and noticed - you can actually hear the difference - that when I jog my machine forward it runs a bit quicker than when I jog it backward. Let's say it does 17 u/s forward and 16 or maybe even 15 u/s backward. Does anyone have a simple explanation of this?

James do you have a linistepper and stepper motor handy to check this out? High power 1, mode0 1, mode1 1, 12v and let it rip to just before the stepper stalls. And then jog back and forth and listen for any differences in pitch.

[James Newton]

The rate at which is steps is decided by the number of step pulses you supply to the unit not by the unit itself. It is possible that the unit could be reaching its upper limit at 40k+ pulses per second (I'm not really sure what the upper limit is to be honest, I'll have to check into that) but in that case it would be skipping steps and not just stepping slower. And I have no idea why the direction would have any bearing on it. Could it be a mechanical issue where the motor is closer to the edge of stalling when going backward?

I'll see what I can figure out.