Cnc Job #2, New Vise Time W/ A Setup Question!

[countryguy]

I have the next CNC job CAM /Gcode for my Plasma torch holder setup. The job is to Mill several holes thru 1/2" aluminum. holes are .375 to 1.25 (pocketing routines). I have wood under the part to act as sacrifice material. ( will go .125 or so beyond the aluminum bottom).
Then there is the dressing w/ a chamfer along the outside top edge. ( I just like them.... dunno why ;-)
We want to do this all in 1 set of Ops if possible to keep the edge alignment. I see similar setups online, in vids, even here look like this - But that does not always make it right or safe.

Being new to part setups in the new vise; Is it OK to put the Aluminum part up & out of the Vise like this to allow the holes and then room for the chamfer edge op? Or should I just bolt it down to the table to run a 2nd setup and ops for the chamfer? End mill is a 1/4" to keep the forces down. (if that even helps?).

thanks everyone,
CG and Son.

 

[Tony Wells]

The real answer kind of depends on how wide your stock is, and how much of an edge break you are putting on. From the pictures, I see no problem that jumps out at me. It is smart to keep the forces low when there is a question like you have here. Small end mills definitely help there.

I would recommend that you begin shopping for a set of parallels though, rather than wood.

 

[JimDawson]

Your setup in the vice looks almost good. You can do all of the operations without running the tool into the vice. I agree with Tony, you need to look into a set of parallels.

 

[countryguy]

I actually do have a 1/8" parallel set. But I did not want to sacrifice them (and they are steel) under the part. Do I try to set them up in a way that they are upright & on-edge as opposed to pancake stacked? There is actually a set in the mix there to get the right height off the Vise.

also the part is 3" wide by 7" long. ;-)
Thanks for the help guys!

 

[countryguy]

On another note- I did hook up the dial indicator to make sure I'm very very square. But went off the part as square as opposed to the vise.... right? It reads zero along the entire length of travel. that was a nice surprise.

 

[Tony Wells]

Normally, the vise would give you a smoother reading, but the fixed jaw should be co-planar with the back edge of the workpiece, so unless there are warts on the material, you're good to go.

And yes, parallels are more often than not used on edge, against the vise jaws. You still have to watch out for them of you have features close to the edge of the part.

 

[Wreck™Wreck]

I have wood under the part to act as sacrifice material. ( will go .125 or so beyond the aluminum bottom).

What in the world is the wood for? That is completely unneeded and will not let the chips fall through and out of the holes, don't do it for that reason among others. Put it on parallels, if needed for clearance knock the parallels out after tightening the vice, endmills have a positive helix angle therefore will pull the part up and out of the vice. Unless you are plowing a large drill at a high feed rate it won't go anywhere.

As to the chamfer or radius op the best way to get a nice even appearing chamfer is to skim facemill or flycut it first, mill the ends then chamfer around it, there is no right or wrong way just the way that works, just don't hit the vice jaws.

 

[JimDawson]

Yes, on edge. In fact, once the part is set up you could actually remove the parallels. The part does not need to be supported on anything once the vice is tight. Just the friction of the jaws will hold it for that operation.

 

[joshua43214]

Use parallels like other have said. Stand them upright under the work, then knock them out if you think they are in the way. Get a cheap set from Shars or Enco and replace them if you ding a corner knocking them out. Like gage blocks, they should be considered a wearable item that will need to be dressed or replaced at times.

You need to push your limits a bit. Until you start breaking stuff, you really have no idea what the limits are of your machine. This can be done safely if common sense is used. You can grip a very small edge of the work in the vise safely provided you have a decent vise and the jaws are in good shape. How aggressive a cut you can make depends on the material, the vise and the cutter. You need to push the envelope a bit to find out. Do stuff like clamp just 3mm of that slab in the vise, put a 10th's DTI on top of it and start cranking the vise down. You will get a feel pretty fast for how tight you can go before the work starts to pop out of the vise. Try clamping 2mm, you will be surprised how tight you can clamp with a good vise, my Kurt will deform the edge of the work before the work starts to pop out. Try to think of other ways to test clamping force, do not shy away from beating on the work with a mallet to see if it moves. Once you have that all worked out, try some crazy cuts (make sure if anything breaks or comes loose it move away from you).

Have fun and be safe

-Josh