Building a cnc router with an old printer and an old scanner

[codemaster]

hi all,
i just started building my own cnc router, i used an old epson inkjet printer the structure and the limit switches and motors, the cartridge charriot is perfect to hold a dremel or other. The printer structure is mounted on the moving part of an HP scanner. the Z axis is still under construction, but i plan to use the paper drive motor. This assembly gives me a working area of an A4 paper or +/- (200mm on 300mm).

I'm now trying to find the specs of my motors. i think the paper drive one is a 48 steps, didn't look at the others for now. From the PCB of the printer suppose they were driven with 42V, as those tracks are marked on the PCB and goes near two completly same group of components that seam to be the drivers, and ends to the two connectors. I added a picture of it.

I plan to use a pic to buffer gcode from the PC and transmit them to related subpic(s). As in the futher i maybe will extend the machine(vacuum,display,toolchange,axis). For now the master unit sends pre-defined commands to hosts. One of the hosts is the axis motor controller, i used a recycled 16F876. the master is for now also a 16F876. in a pic simulation software the calibration or home-run procedure works perfectly but i dunno how to build this out...

I miss a part between the pic and the four wires of the motor. with a multimeter i got a little 9 Ohms between wire 1 and 3 and bewteen 2 and 4. I suppose this are my coils. but i'm missing some knowledge about that, i found some shemes on th net but hey are for 5 or 6 wire motors and i don't see how to adapt them. Could anyone help me with that... On the other hand i will have to look for opensource G-Code software. anyone has clues on that one maybe?

Regards

Sorry for that broken english i have..

[codemaster]

I finished the scanner body work, I had to cutout the whole plastic bottom of the scanner to have a deeper workarea, Now i have at least 1inch more in depht. I'm still blocking on the transistor part for those steppers. The Z axis is almost finished, I will make some picts of the machine in the actual state.

[paulC]

Pminmo has done a lot of work on drivers that he has published.
http://engraving.majosoft.com/html/P...inmo-com-.html

Just a warning: The steppers from most printers don't have a lot of torque so will not be able to push a dremel without gearing. You really need some more substantial steppers.

Paul

[codemaster]

I took some pictures of the thing, i would really apreciate some help on the transistors stuff..

[codemaster]

Originally Posted by paulC Pminmo has done a lot of work on drivers that he has published. http://engraving.majosoft.com/html/P...inmo-com-.html Just a warning: The steppers from most printers don't have a lot of torque so will not be able to push a dremel without gearing. You really need some more substantial steppers. Paul

Thanks,

I will look for better steppers, or maybe i will use a flexible to connect the dremel this allowe me to use a small servo for the Z axis.

[TinkerDJ]

My first router i used the carriages from two printers and made a body out of mdf, then used the belt drives and the shafts from the printers to hold everything. it worked okay and i guess i could have continued using it. I got lucky one of the steppers was big enough but the x axis one was not so i found a bigger stepper and fixed that. I should have used the shaft for a spindle rather then mounting the dremel. I think it was too heavy. I was using a ucn5804b board design which has been around for a long time. The chips are obsolete now. And Phil has some excellent designs on his site as well. Most of those chips can be had as samples aswell. I blew one of the chips on my board and started building a new controller board, got carried away with design and have upsized a bit and am still working on another design. I was using drawer slides and the backlash was horible so i went to bearings and rods. I got the bearings from vxd bearing on ebay 100 bearings for 15bucks.
Heres some old pics of the controller board now deceased and my base as i was building the router. JGRO's design in diy wood router section is awesome as well, works well just to have the pdf file and see how things are built in that design.

Phils site a must have.
http://pminmo.com

[codemaster]

Thanks Dave,
pminmo's site is great, i took a looky on his boards and adapted something, i took a board based on the L298. The one on the site uses also the L297. But i think i may replace this with my Pic. here is the current sheme, the battery is of course not a battery and it misses a couple of 100nF capacitors. I'm also a little bit confused about the sense pins...

[codemaster]

i think this thread is in the wrong place i just took a looky on open-source specifications and this is not what i'm doing lol i'm sorry, could an admin or moderator displace this thread ...

[codemaster]

I just informed for the price of a L298, those chips costs almost 6 dollars / pc here, damn, i will take another looky to find something cheaper

[vulcom1]

I made a EDM board which is not cnc but was supposed to use the 5804 chip. I could not find any so converted to the mc3479 which is close with some pins reversed.
Hope this may be of help.
John

[codemaster]

Originally Posted by vulcom1 I made a EDM board which is not cnc but was supposed to use the 5804 chip. I could not find any so converted to the mc3479 which is close with some pins reversed. Hope this may be of help. John

Thanks for the reply the mc3479 is max 16v, i need 42v, I will use those expensive L298 but build the controllers one by one, and wait a little bit(after new year... Maybe Santa will see this before he gets off....). Somebody told me and hé it's logic 'higher the power, higher the price'

I'm setting up the limit switches right now.I found a litttle vacuum and just started the schemes for the master controller. This board is the head of the machine, like it said it stores the G-Code from the computer and reports status information. I have an old Ethernet->RS232 converter with telnet and all the stuff... maybe I will use it but I prefer to hold it for a better application. I'm also spending a lot of time on learning the M and G-codes, I try to generate them from bitmaps with c-sharp.But that's not really easy. anybody knows a software ? maybe

Thanks for the replies

Regards.

[vulcom1]

Concerning the mc3749 chip, I use 4 2n3055,s to the steppers. The board is on 8 volts regulated with a 7808 and the steppers operating on 24 volts 5 amps. I think you could boost it to what you want as long as the power transistor's can handle it. My stepper is also from a printer and I am going to use more for a foam cutter/gantry style combination. This will be cnc.
John