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Cutting sides of stock in a CNC mill

K

KaiserGlider

Plastic
Joined
Oct 8, 2017
Location
San Diego, California
I will soon be required to cut stock up on the bandsaw and then cnc mill the sides down to the required tolerance, so I was just wondering if my plan will be sufficient or if there's a way to ensure higher accuracy from the get-go.

Let's say after using the bandsaw I have some 6" wide plates that I want to cut down to 5.8" inches. Step one, I stand the plate up in the vise, probe the top for Z and then face off .1" of material. Step two, I flip the plate over, probe the top again and remove .1" of material. I measure the plate to see how close I am to 5.8" and adjust my Z height on the machine if necessary before running the rest of the plates all at once.
 
How many sides of the plate do you need to do? Just 2? I would just scribe two lines 5.9” apart in my subplate and clamp it down so I can’t see the lines and just side mill the damn things.
 
unless you are using very light cuts,4 inches above the vise jaws is going to chatter a bit. 2nd clamping to the table. If the plates aren't real flat it will make it worse with poor contact with the jaws.

Dave
 
Standing them up to mill you’ll have to carefully square the sides to the vise otherwise you’ll get a parallelgram not a rectangle.
 
What's with this probing thing????

You know its 6" tall, you know where the bottom is, so you know where 5.9" from the bottom is,
same for the 5.8" cut...

As for standing up that high out of the vise, depends on how thick your stock is. 3/8" thick
standing up 6", grabbed on 2" or so, you are going to have a HUGE problem.. qty 5 3/8" plates
clamped together and stood up in the vise.... Not a problem. Single 3/8" plate sandwiched
between some 5" tall 1" thick plates, no problem there either.
 
If they are long enough, I would lay them flat and side Mill them in one set-up. Better for Parallel and Perp. Reduces the chance of setting on a burr or a chip or dirt or used condoms.

R
 
KaiserGlider said:
Step one, I stand the plate up in the vise, probe the top for Z and then face off .1" of material. Step two, I flip the plate over, probe the top again and remove .1" of material. I measure the plate to see how close I am to 5.8" and adjust my Z height on the machine if necessary before running the rest of the plates all at once.
Click to expand...

I'm with the others here -- if you only need to do 2 sides, clamp the plate down on some sort of riser and side mill the 2 sides.

If you really do want to stand the material up in the vise, just probe the bottom surface of the vise one time, and that's all you'll need from that point on. Write the first pass of your program at +5.9" off the vise, put an M01 after that and follow it with a return trip at +5.8" off the vise and Bob's your uncle. :)

jmho
PM
 
KaiserGlider said:
I will soon be required to cut stock up on the bandsaw and then cnc mill the sides down to the required tolerance, so I was just wondering if my plan will be sufficient or if there's a way to ensure higher accuracy from the get-go.

Let's say after using the bandsaw I have some 6" wide plates that I want to cut down to 5.8" inches. Step one, I stand the plate up in the vise, probe the top for Z and then face off .1" of material. Step two, I flip the plate over, probe the top again and remove .1" of material. I measure the plate to see how close I am to 5.8" and adjust my Z height on the machine if necessary before running the rest of the plates all at once.
Click to expand...
.
.
what you want to do i have done (a few times) when i scrapped a part and went to rack and saw cut a smaller piece and milled it so sides parallel enough and close enough to original blank piece on job i scrapped
.
doing it fast sometimes doing quick conversational programming is common. usually dont take a lot of time cause i dont want boss to know i scrapped a part. if its a small part its no big deal..... usually takes 60 seconds to program. like i said its a thing you do as fast as possible
.
also do it on torch or plasma cut stock as you need a good surface for vice to clamp on if going to do heavy roughing with a big 2 to 6" dia mill
 
KaiserGlider said:
I will soon be required to cut stock up on the bandsaw and then cnc mill the sides down to the required tolerance, so I was just wondering if my plan will be sufficient or if there's a way to ensure higher accuracy from the get-go.

Let's say after using the bandsaw I have some 6" wide plates that I want to cut down to 5.8" inches. Step one, I stand the plate up in the vise, probe the top for Z and then face off .1" of material. Step two, I flip the plate over, probe the top again and remove .1" of material. I measure the plate to see how close I am to 5.8" and adjust my Z height on the machine if necessary before running the rest of the plates all at once.
Click to expand...

.
.
usually easier to have what if big passes
.
you use extra pass or 2 in case stock is .150 or .300 big. if mill doing 20-30ipm it doesnt take much time making extra passes rather than probe and then do extra passes
.
what if big passes are common on saw cut stuff, torch cut stuff, castings where size can vary even .25" easily. worst that happens you are cutting air if stock not extra big but extra pass should be like 30 seconds so no big deal
 
Bobw said:
What's with this probing thing????

You know its 6" tall, you know where the bottom is, so you know where 5.9" from the bottom is,
same for the 5.8" cut...

As for standing up that high out of the vise, depends on how thick your stock is. 3/8" thick
standing up 6", grabbed on 2" or so, you are going to have a HUGE problem.. qty 5 3/8" plates
clamped together and stood up in the vise.... Not a problem. Single 3/8" plate sandwiched
between some 5" tall 1" thick plates, no problem there either.
Click to expand...

Right -- obviously there may be some tolerance consideration, but if I have multiple plates to bring to size, my first thought is "How many can I do at one time?", which means a stack held in the vise, and plane the edges down with a BIG ole' cutter. YMMV.
 
Would have helped if you had stated the thickness of plate.If your swaying towards vise opposed to clamping on table say you had twenty at quarter ins thick you could load ten obviously the more you have sticking out vertically you need to support the plates say couple of ins blocks one either side of job to act like a higher jaw to prevent "flapping" you dont want them sticking out without some support as the tool has a chance of grabbing one due to the flapping(vibration)and your tool will be destroyed just set a stack of slips to the height of plate and zero the height in
 
KaiserGlider said:
I will soon be required to cut stock up on the bandsaw and then cnc mill the sides down to the required tolerance, so I was just wondering if my plan will be sufficient or if there's a way to ensure higher accuracy from the get-go.

Let's say after using the bandsaw I have some 6" wide plates that I want to cut down to 5.8" inches. Step one, I stand the plate up in the vise, probe the top for Z and then face off .1" of material. Step two, I flip the plate over, probe the top again and remove .1" of material. I measure the plate to see how close I am to 5.8" and adjust my Z height on the machine if necessary before running the rest of the plates all at once.
Click to expand...

.
6.0 rough cut then milled to 5.800
.
you need to cut straight to 0.100 or straighter
.
if saw cut stock min 6.0 to 6.2 max
1) best side down in vise start mill at 6.2 (max size) mill passes to 5.900 cause you saw cut straight to 0.100
2) flip part mill 5.9 down to 5.800
.
so you start milling at 6.2 (max size) and if it was 6.0 (min size) you cut air for 1 or 2 passes depending if rough stock at min or max size
 
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