drip feeding

[stevieboy]

I've got a bmc 20 with ultimax 3 control. I'm using mastercam for any complex profiles and up to now I've got awat with the programs being no more than about 5000 lines so I just put them on a floppy and bung it in the side of the pendant. I've got to run a program now that is 46000 lines, obviuosly it doesn't fit in the memory.

I've got a network cable for this machine from the guys that I bought it off but I've never done any drip feeding before. Any tips on what to do, things to watch out for.

[bloke]

Hi, Steve.
If you have an old PC that can run DOS programs, I can mail you a copy of the Hurco upload/download utility. PM me an Email and I'll get it on it's way.

[stevieboy]

Hi Bloke,

I pm'd you my email but not had anything back yet. Did you get to send it. Probably gone in the junk mail folder and I missed it.

[bloke]

I have sent the files. If you can't find them in your junk folder, give me a nod and I'll re-send them.

[stevieboy]

They must've gone to the junk folder and I've missed them then. I get so much rubbish I often don't bother to look in it, just empty it, sorry. Any chance of sending them again and I'll make sure I look out for them properly this time.

Thanks.

[bloke]

I've sent them again.
Cheers!

[stevieboy]

I got them, cheers bloke.

Unfortunately I can't open them because;-

"Windows Live Hotmail has blocked some attachments in this message because they appear to be unsafe".

Great.

[bloke]

I'll re-send them to ya tomorrow but zipped up.

[stevieboy]

No that doesn't come through either Bloke. For some reason hotmail blocks the attachments because they "appear to be unsafe". Are these files something that I have to put in the machine control like an update or do they go on the PC. If it's to go on the machine then I think I may already have them. Perhaps that's why the previous owner gave me a network cable for it. Perhaps a wiser man would've thought to look. Doh.

I've spent most of the day messing around with the mill and actually got somewhere. I've managed to go into auxilary more and there's a download upload softkey. After much faffing about I've configured the two ports to be.

Port 1: level 2 Xon Xoff
baud rate 9600
data bits 7
stop bits 1
parity even

Port 2: level 3 full handshake
baud rate 9600
data bits 7
stop bits 1
parity even

Nothing else seems to work. I can now upload a program from Mastercam to either of these ports and run the machine in drip feed mode. If I try level 1 CTS/RTS the machine stops when the buffer fills up and tells me there's no start to the program, because it's ditched it of course.

What I've got now is this. The part I have to machine is a multiple cam profile that's been drawn as a series of elipses. This means it's not curves but a series of tiny straight lines, there's approximately 5400 of them in one pass around the contour of the part. As I run the program the feedrate is very slow at around 200 mm/min but in Mastercam the toolpath is created with a feedrate of 1000 mm/min. I think it's because the machine can't process the information fast enough.

I've proved this by cutting the program down to just one pass and at 5400 lines it just fits into the memory with 16% free, then running it from there instead drip feeding. Still the same, feeds slow, so obviously not a drip feed problem like I first thought. Also the cutter feeds in to the profile on a single arc at 1000 mm/min then slows down as it cuts the contour (fresh air for now).

I've noticed before with this machine when I'm cutting a relatively small internal arc that the feedrate drops in this way, either in NC or conversational mode. What's the reason for this and can it be changed.

[bloke]

You can load the program straight to the hard disk and run it from there. In the NC side, go to the port setup and change the speed to run as fast as possible (115200 if it will stand it without erroring). Change where the program is stored (change it from memory to disk file) it will ask you for a filename and save it to that. When you run your program, do it from the file and it will drip feed from hard disk a lot quicker than serial transfer.

Try changing the chord error in program parameters to something very slightly bigger.

[stevieboy]

Hi Bloke,

I tried sending the file to the disk and running it from there but it didn't make any difference. If I set the baud rate any higher than 9600 it throws up an error when trying to transfer the file. I think it's simply that the control can't process the information fast enough to make the machine move at that speed. One thing I haven't tried yet is setting the feedrate as feed per tooth instead of mm per minute. Maybe that might make a difference. I think I'll need to do that in Mastercam as it will need to output the appropriate G code. For now at least I can cut the part.

Thanks a lot for all your help.

Steve.

[gthlm]

If the ultimax 3 is anything like the 2, you can just set the chord error to 0 and the control will default to feedrate priority like every other control. You'll then need to use trial and error to find the quickest feedrate that your machine can contour at and maintain acceptable accuracy, but it WILL move at whatever feedrate you program (upto a max. of 2540mm/m on mine which is pretty annoying since it'll accept 4000mm/m in conversational)