Need Help!- Which way is correct to rough out a raw material?

[Nitwit]

Hey Guys!

My "MD" engineer said, there is no one know how to do CNC in this world, there is only five people, which included him.

Therefore, I wonder, does anybody know which way to rough out a raw material so you can make an open slot?
Does it matter what kind of material we use?

Lets say if you must open a slot with 0.500" in diameter or radius, you can not mill or rough from a "fixed jaw" to a "loose jaw". Yeap! You heard me right. "Loose Jaw". Not a moving jaw. In other words is that you can not mill or rough from Y+ to Y- jaw before you make a final cut with G41 cutter comp and G03 to finish it.

Ok, that is the Y+ to Y- direction.
How about if you mill or rough in X direction?

There is no fixed jaw or "Loose jaw" in both end X+ and X-. Which way do you have to mill, or can you go back and fore before you use G41 cutter comp with G03 to finish it?

Does anybody know which way is correct and the fastest?

-Nitwit

[DMF_TomB]

not exactly sure what you are getting at. if you are talking about cutting forces against movable jaw in a open slot you can mill from the left side or from the right side so you are pushing against fixed jaw.

an open slot being squeezed in a vise is better being clamped down to a plate as an open slotted piece will close up from vise pressure as you mill it.

if piece is 0.500" thick / depth. you could mill shape out of 0.625" thick material flip it and insert something tight in open slot so when you mill off 0.125" open slot is not squeezed or collapsed.

trochoidal milling or cutting arcs / circles and advancing cuts chips on periphery or radius of an endmill. general you can cut a deeper depth of cut and at a 10% stepover still cut faster than conventional end milling.

if you are talking about cutter comp. most machinist use a cad cam program that tells machine to run with no cutter comp. rather the CAM software did the math as opposed to asking the hardware CNC machine to do it.

you can manually create gcode but far easier to have a CAD CAM program like MasterCam figure it out. If you are engraving letters I got better things to do than manually figure out gcode and cutter comp. It is far easier to have a program like Millwrite or MasterCam figure it out. it should not take more than a few minutes to create with Cam program and upload to a CNC mill and engrave letters and be done with engraving in a total of 20 minutes or less.

i would never be wasting time manually figuring cutter comp

[Nitwit]

Dear Mr. DMF TomB,

Sorry for not giving you complete information about my question.

I totally agreed with you-if I cutting longer than 6” slot side way which is from X- to X+ the part will be squeezed in a vise. The slot will be bigger in the middle than the two ends. That’s why I came up with the question, “Can I cut or rough from Y+ to Y- or in reverse? Which way is the correct way to do so?”

According to my “MD” engineer said, “It is only way to cut from Y- to Y+ only and never in reversed. “

OK. That’s Y- to Y+. How about working in X direction where there is no fixed or moving jaw to hold the part? How can you cut or rough out material before using cutter comp to finish the radius size? Only one way from the left to the right X- to X+, Or from the right to the left X+ to X-?

If you do so, your program will have a ton off Z0.1 in there because you must lift up the tool and start again in either direction to cut it before you using cutter comp to finish the slot radius.

My main question is : Can I cut from Y+ to Y- or can I cut from Y- to Y+ or both in either way to rough out the material first before I use cutter comp to finish the dimension is required without lift up the tool and re-start in either beginning point.

Using MC software to generate or figure it out the way or G-Code to cut the radius for you is always the best. However, your job shop is request one piece per order, are you going to sit there and use MC software all day long to figure out how to cut it for you?

MC is good, however, it also created a lot of none necessary move and Z0.1 in the program. It makes the program just too long and too confusing for a small job, and creates all the unnecessary N-Block number.

Figure by hand how to cut a 1.0 inch long slot and ½ radiuses is not too difficult if you understand “How” and the basics of it. It will be very helpful for any small job rather than involve with MC software program.


Today, I have another question for you guys.

If a drilled hole was 0.02” over size it simply because:

A. The nut set inside the tool holder used to stop the drill was removed or set it incorrectly?

B. Someone used a Permanent Marker to mark on that tool holder to make it out of balance?

C. The drill was grinded incorrectly?

D. All of these above.


Thank you for your comment and response.

[Shane123]

.02"???? you got some issues if your .02" oversize on a drilled hole..... use a precision tool holder or collet setup, or check your spindle..... .02" it out there man....

[MrWild]

over sized drilled holes only happen when the drill is ground wrong. One side is longer than the other side, or one side has a different angle than the other.

Magic marker will not imbalance a tool.

A loose spindle will not make an over sized hole if the drill is ground correctly. The drill only cuts with the faces, not the sides, and a proper drill will guide itself.

You can rough out an opening by plunging in the Z, then raising the Z and moving X or Y and plunging again. Never move more than 1/8 the cutter diameter in X or Y before plunging the Z again.

[DIFF OVER]

Originally Posted by MrWild over sized drilled holes only happen when the drill is ground wrong.

Not true. A high speed and low feed can make o/s holes. Even at proper sfm for a material, too low a feed can create harmonics that influence hole size and straightness.

[Nitwit]

Originally Posted by Shane123 .02"???? you got some issues if your .02" oversize on a drilled hole..... use a precision tool holder or collet setup, or check your spindle..... .02" it out there man....

"We" use tool holder for Haas machine.

The whole idea is our "MD" engineer said because of someone took out the stop nut set in side the tool holder or someone make a mark on the tool holder that make it spins out of balancing.

Can you believed that? What kind of "MD" he is?

Thank you for your comment and replied.

[Nitwit]

Originally Posted by MrWild over sized drilled holes only happen when the drill is ground wrong. One side is longer than the other side, or one side has a different angle than the other. Magic marker will not imbalance a tool. A loose spindle will not make an over sized hole if the drill is ground correctly. The drill only cuts with the faces, not the sides, and a proper drill will guide itself. You can rough out an opening by plunging in the Z, then raising the Z and moving X or Y and plunging again. Never move more than 1/8 the cutter diameter in X or Y before plunging the Z again.

===========================================

My certified die maker Co-worker told me the same thing like whatever you said.

A thirty years experience person who can write program at the machine and operate it to make a part always better than a person who just read the book and click on the geometry DXF file for MC software to make a program. Which one do you thing I should believed?

Here I have another question for you.

A. The Grind stone table weights a ton. If you set a folding chair next to it, will it throw out the table level?

B. If the table out of level. Let say 15-deg. Will you have incorrect reading from the height gauge sit on that table?

Let see if My "MD" engineer correct this time?

[headsmess]

i see someone likes talking about this engineer, but so far hasnt gotten this engineers job....

do i see green or should i try reading backwards?

.02"? inch? 2/100 of an inch? .508mm? and magic marker is listed as an option?

there is no-one, yet there is five people that can cnc in the world... thats a really tough call. this guy must be charging 6 figure sums an hour...

*setting up 252 turret mills in the blink of an eye, he machines yet another ultra complex injection mould die whilst mandrel bending n welding up extractors for the beetle without even raising a sweat, and this is all before morning tea!*

[mopar]

Need to rename this thread to ME bashing..
with that said DON'T OPEN THE SHOP DOOR THE MILL WILL GROW .04 .I heard that one before

[MrWild]

Used to work with a OD grinder that would change taper through the morning until break time as it came up to temperature. Boss asked once why it was moving side t side with no part in it right after morning bell. I asked if he wanted scrap or pay for the 20 minutes the machine needed to normalize. He decided good part were more important. .040 though? No, we were talking .0014 over 14 inches. Had a coworker that couldn't get the machine to produce zero taper no matter what he did. While talking about the issue, I noticed he liked to lean against it. Naturally he was leaning against an area you shouldn't lean against and was causing all his own problems. Once he stopped that, his life was bliss.

[RICHARD ZASTROW]

Then there was the sun shining through a skylight. In the morning it warmed up the east side of the HBM column and in the afternoon, the west side of the column. Column lean changed during the day. Solution: paint skylight glass light grey.LOL

Dick Z