Cutting knife methods

Guys-

We often recut/resharpen knives which vary from 2-4" tall, and from .500-.750 wide. They vary only from different part numbers, meaning when a part number comes in for resharp, they will be all the same size. At times we can cut up to 100-200 of these.

My current method is to hold these parts in a vise on the table, and I cut 1, and reinsert the next and cut again. Works pretty well except I have to be around the machine every 20-30 min (depending on the part) to change the part out. Doesn't make for me being very productive in other areas. Is this how you guys would approach the job?

The thickness or width (section I grab with the vise) is ground....so I had in my head that maybe I could stack these parts say 10 wide and make the machine cut for a half a day or something then come back and knock the slugs off maybe? I haven't done that type of work before but it sure might save time. And another concern is the ground width this time might be .4995 and next time it might be .499, so if you program .499 and they are .4995 by the time you get to the end of the 10th one you would be quite a ways off center. Curious is there is a way to make up for this in the program.

Thanks
Brad

Hi Bradracer:
The most obvious solution is to make a gang vise that clamps your knives exactly the same way you're doing now, but allows you to clamp a number of these, each in a station whose position is known.
Since these knives don't vary much in dimension, you don't need a very elaborate vise: you can make a very small clamping range with a setscrew or a tapered pipe plug or whatever to allow you to shift the moving jaw just enough to clamp the parts.
Wire the whole vise from a single block; no elaborate separately made and fitted sliding jaws!!
You only need the moving jaws to move a few thou.
If you have to make a different vise for each part number, that's not a big deal.
The plan is to make them so simple it doesn't take much to make each multi station vise.

Once you know where the reference face is for each station, the programming becomes a simple subroutine with incremental moves between and a G55 G92 call for each station in succession.
Program the main in G54 and the sub in G55, and you're good to fly.
Cheers

Marcus
Implant Mechanix – Design & Innovation - home
Vancouver Wire EDM -- Wire EDM Machining
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And possibly even build each "location" with a symmetrical flexture, so each knife ends up being located on centerline in reference to each "vise" location. (I'm making the assumption that it may be better to know knife centerline rather than one face or the other)

If it turns out that stacking parts is a solution but you are feeling too gun-shy to try it, perhaps you can start small. I say this for two reasons:

1. Sometimes just doubling-up is enough to make the job work for you. No need to stack 10 high (for example) in many cases because...

2. There is a definite point of diminishing return on the height of your stack in regard to the rate it can be cut. Check your technology files and plan to cut stacks that are ideally suited to your exact machine's situation, (stack height, flushing/fixturing methods, etc.), when possible.

Ok thank you guys I'll work on it more! Thanks for the idea! and yes, the centerline is the ideal point, right now I zero off the centerline.

Joe, the parts are stacked 90 degrees from what you are thinking, stacked across the table, not stacked upward

I misunderstood your setup.