[Joe Miranda]

We have been getting into 3-D work lately and we have landed a fairly large surfacing job. Not particularly complex but there is not a flat surface on the part. It's a 12x12x2" aluminum plate that is radiused 10" across the part.

My question is how to go about machining this since the file is too large to fit on a floppy. Sure we can cut the file up into bite size pieces and make sure that there are proper Z moves for tool changes but I know guys are doing something they call "drip feeding" and I am wondering if that is a possibility for us. Or if there is another way you guys have found to tackle this issue.

I know it is nothing new for most of you but I'm an old guy and not real tech savvy.

To give you an idea of the file size it's about 287,00 lines and about 8953kb.

Thanks,
Joe

[petesurrey]

you would need to let us know your control and machine type.
For example with a Heidenhain equipped arrow you can use file server over rs232 from a PC. This allows you to read blocks that once machined are then forgotten.
The biggest problem comes with how your arcs are generated. If your cam software splits the arcs up into thousands of small lines then the file size becomes massive.
I have runs hundreds of programs that are over 2 millions lines. The issue I had was the machine going faster that the program transfer speed.

You will need to have a PC with RS232 of if your lucky your machine has ethernet. Then you can drip feed or DNC.

[Joe Miranda]

I have a Cincinnati Arrow 500 with the A2100 control. By changing from closed loop to traditional I was able to get the file size down to a reasonable size and now I can fit it on a floppy and then run a finishing op. But I would like to figure out this "drip feeding" thing because I would really like to run "lights out" more often.

As it is, the roughing program is about 3 hours and the finishing is about 6 hours. I have three of these plates to run so if we finish the first plate during the day and get the second plate setup then we come in to a half finished plate rather than a finished plate and it takes me an extra day to knock these out.

Not a big deal on this job because there is enough money in it that we'll be fine but when we are cutting margins to keep work coming in the doors we need to be able to run lights out more often.

We recently had a job I quoted at about $900 ea. and I thought we were super competitive and that no one could touch our quote. I was fine against the local shops but the customer had it quoted by an outfit in China and they came back with a quote of $350 each. Wow! My material cost was half that. I think that if I could have gotten the price down to around $500-$600 I still would have gotten it because of turn around time but I jut couldn't do it for $350. You know the routine.

Thanks for your help.

[Superman]

You could also look at the pattern your toolpath follows to lower the number of points
ie travel parallel to the arc axis so the tool doesn't change much in Z movements, ( long linear moves )

a surfacing operation that expands to / from the centre would create a very large file

- HINT.... the larger the radius in contact with the surface, the larger the stepover you can use to achieve the same finish
( Scallop (or cusp) height.....this is the height difference between 2 passes, ( intersecting crest & the valley of the cuts)) LINK

If you use a CAM system, try to use a bullnose cutter instead of a ballnose ( ballnose don't like cutting in the centre, but, sometimes you may have to )

[Joe Miranda]

Superman - using the "traditional" tool path function in our CAM limits the Z movements. That was a huge savings in file size vs. the "open" or "closed" toolpaths which basically move back and forth with constantly varying "z" movements.

I rough with a bullnose and then switch to the ballnose for finishing - also a huge savings. Thanks for the recommendations!

[maver1ck]

I've never seen a reason to drip feed the A2100 control. Unlike the limited memory of other controls back then, most of the A2100 controls had 2GB to 80GB hard drives in them and the smallest hard drives were 540MB, so there was plenty of room to store programs on the hard drive. Even if you didn't purchase the upgraded part program storage option, you can save the file to the hard drive and then run it from there rather than worry about drip feed rates.

Getting the large file onto the hard drive would either have to be done by spanning the file over multiple floppies, use RS-232, or Ethernet (but if you have the Ethernet option you can just run the file from the network and don't even need to transfer it to the machine).

[Joe Miranda]

maver1ck- where the door on my arrow shows "RS-232 and Printer" there are two 25 pin serial ports. Is one of those configured as an RS-232?

[maver1ck]

I can't speak for what is configured on your machine now, it has been 20+ years, and more than one owner so I don't know what changes may have been made.
When the machine shipped from the factory, those 2 ports (1 serial, 1 parallel), were configured as indicated (RS-232 and Printer). If nothing was changed, yes, the RS-232 port should still be configured properly.

[Joe Miranda]

Oh...one serial and one parallel. Ok. I have been reading on the internet and see that 25 pin serial ports were standard for RS-232 in the olden days. I didn't know that. So now the question is how do I connect that to my pc (laptop actually)?

On the pm site I have gotten several comments about having to make an adapter. I was thinking that they probably have these already made up somewhere.

[maver1ck]

You can buy adapters, but every time I set a machine up for a customer I just make a custom cable for them. That way it is the proper length and can be configured for their particular system. Some shops use a 3 wire setup, others require more (depending on handshake protocol), many need to have wires crossed to accommodate switchgear in line to the control. It is rare that I can ever walk in with a null modem cable or adapter and have everything work. There is also a problem that I have seen different companies use different pinouts for a "null Modem" cable.

I know I'm making this sound complicated, it shouldn't be, and if you do them enough it is not, but in the real world, it is rarely as simple as it should be. Each shop uses different software packages, settings, and switchgear. I've seen shops chain multiple cables together, each one randomly crossing the signal wires so I have to pin out the cables to determine exactly which wires they crossed (and where). It usually becomes easier to just replace everything with a single custom cable suited to the specific needs of the shop.

If you keep it simple and go straight from your PC's serial port to the A2100 serial port, a null modem cable should work. Then again, when is the last time you bought a PC with a serial port on it? Unless you have an old computer/laptop laying around you will likely have to buy a USB to serial port adapter (some of which cause their own problems). You will also need to determine what software you will be using for communication to the A2100 and ensure it and the A2100 control settings are done properly (and match). Old versions of windows had a free software that was capable of this, but I believe they phased that out after XP.