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Carbide Insert Tooling

Menessis

Aluminum
Joined
Feb 23, 2011
Location
Ontario Canada
I don't know much about the insert tooling. But I do have an R-8 mill that I'm trying to learn how to use.
It seems to dull quickly and or chip an edge. So before I ruin more inserts I should figure out what I'm doing wrong.

The last attempt working on mild steel. I used the numbers from The Little Machine Shop.IMG_0718.jpg
And things where going smoothly until it wasn't. I think one of the inserts chipped. I was taking light cuts just cleaning up the surface when it failed. I was using 720 RPM. I wasn't feeding as fast as what the calculator says to. I was very slow in comparison at 3 ipm. Will a slow feed rate cause problems?

I dug up some inserts to replace the dull/chipped ones. I think they will fit the tool fine.
IMG_0719.jpg

Any thoughts?
Thanks
Menessis
 

Milland

Diamond
Joined
Jul 6, 2006
Location
Hillsboro, New Hampshire
Bridgeport-style mills and cheap carbide inserts don't really go together for "real" work. You might find that old-time high speed steel shell mills on short arbors work more reliably, cobalt HSS if you want to spend more money gives longer life.

Anything you can do to improve stiffness of the setup (no quill extension, solid vise mounting (no swivel), bring the knee up and lock all non-moving axis, etc.) will help a lot, but doesn't make up for the over-all flexy machine.

For a 2" ~10 tooth shell mill, conventional mill at lower RPM, about 30% cutter width of cut at shallow depths, less if you cut deeper. Play around a bit and see what works for you. Use a cutting oil and watch the edges of the shell mill, lower RPM and heavier feed is a better trade off than trying high speeds and lighter feeds.
 

michiganbuck

Diamond
Joined
Jun 28, 2012
Location
Mt Clemens, Michigan 48035
Sometimes a part may not be solid down/tight to a vise floor. A couple of thousandths of empty space under a part can cause chatter/vibration.
A double shim on a vise floor might tell if a part is not down tight.
 

Vecair

Aluminum
Joined
Feb 19, 2017
Location
Prescott
Menessis, I run an Excello mill and its best to run inserts fast and hard. If you have the power try it and see. You should be making blue hot chips and fast!
 

RJT

Titanium
Joined
Aug 24, 2006
Location
greensboro,northcarolina
Hate to break it to you, but you have a very light duty hobby grade machine. Stick with high speed tooling.

Sent from my motorola one 5G UW using Tapatalk
 

Tony Quiring

Titanium
Joined
Nov 5, 2008
Location
Madera county california usa
With our BP the previous owner converted varispeed to fixed and added VFD.

They has 3 phase so the little 1 HP motor driver by 1 HP vfd so we are torque limited.

Our shell mill with replaceable cutters works well but if cutting steel we use back gear for needed torque and just take our time.

Your machine is lighter by far so you may consider same if you have back gear.

If not then lesser aggressive cuts.

Sent from my SM-G781V using Tapatalk
 

DMF_TomB

Diamond
Joined
Dec 13, 2008
Location
Rochester, NY, USA
I don't know much about the insert tooling. But I do have an R-8 mill that I'm trying to learn how to use.
It seems to dull quickly and or chip an edge. So before I ruin more inserts I should figure out what I'm doing wrong.

The last attempt working on mild steel. I used the numbers from The Little Machine Shop.View attachment 341288
And things where going smoothly until it wasn't. I think one of the inserts chipped. I was taking light cuts just cleaning up the surface when it failed. I was using 720 RPM. I wasn't feeding as fast as what the calculator says to. I was very slow in comparison at 3 ipm. Will a slow feed rate cause problems?

I dug up some inserts to replace the dull/chipped ones. I think they will fit the tool fine.
View attachment 341289

Any thoughts?
Thanks
Menessis

carbide even 1/2" carbide end mill (small machine many stay with end mills)
200sfpm or 800/.5 = 1600 rpm x .002ipt feed x 2 teeth = 6.4ipm feed
.
0.5dia at 0.1" depth at 6.4ipm feed = .32 cubic inch per min with steel about 0.32hp
.
300sfpm or 2400rpm x .003ipt feed x 2 teeth - 14.4 ipm feed
0.5dia at 0.1" depth at 14.4ipm feed = .72 cubic inch per min with steel about 0.72hp
.
most small mills max out at .5 or 1hp or .5-1.0 cubic inch per minute
steel cutting.
.
side note mill scale or rusty steel outer layer is abrasive, some steel has small slag or hard spots
especially structural steel, both can dull cutters.
.
also long end mill in long tool holder and mill not rigid and slide locks or gibs not tight even 1/4 tight
the cutter and work piece can vibrate easily damage cutters
.
start small say 0.5" end mill try 0.010" depth at slow feed see if it can handle it then work your way up
to see what machine limits are
 

michiganbuck

Diamond
Joined
Jun 28, 2012
Location
Mt Clemens, Michigan 48035
Inserts may not be as sharp as HSS so need a heavier machine, Some inserts have the wrong clearance angles for certain cutter bodies. Some inserts are the wrong grade for certain materials. A damaged cutter body may have one high insert so that high insert tries to do all the work.
 

Menessis

Aluminum
Joined
Feb 23, 2011
Location
Ontario Canada
Thanks guys. A lot of food for thought.

While pondering the problem I thought about using a fly cutter. I don't have one yet. Its on the list of things to do. But I do have a boring tool :) So I set that up at about 2" diameter. Seems to work ok. Need to refine the grind. But I noticed the machine is out of tram! It's close but no quite. I don't think that would damage the inserts though.
Also the piece of steel (the one I was using the carbide inserts on) did have rust on it. It looked like it was stored and beginning to rust and some body put some oil on it. So it was rust colored.

I installed the GWizard software. And it seems like it agrees more or less with what I was doing. That is nice software. Even I can understand it! If it keeps me from ruining 2 mills a year it pays for itself!

So I'm off to do some tramming! and some more experimenting.

Menessis
 

Bobw

Diamond
Joined
Feb 8, 2005
Location
Hatch, NM Chile capital of the WORLD
Those are TPG's..

And its not even one of the "high end" TPG facemills. the inserts
are standing straight up and down.. Zero rake.

Throw that thing in the trash, or sell it for a couple dollars on e-bay so
somebody else can throw it in the trash.

TPG's should be illegal. Selling Low End TPG facemills to newbies should
be punishable by having to machine Inconel valve bodies on a desktop mill with
only carbon steel tooling.

Even an APKT is going to be far better, and they are cheap. And your life and machine
will thank you.. There is a lot better stuff out there, but the $$$ go up quickly,
Sandvik R390s are pretty sweet, but they are also pretty pricy.

1 INCH APKT END MILL
 

CITIZEN F16

Titanium
Joined
May 2, 2021
Hate to break it to you, but you have a very light duty hobby grade machine. Stick with high speed tooling.

Sent from my motorola one 5G UW using Tapatalk

Show the whole set-up, lack of rigidity could be what is chipping the carbide, feeding too slow should not cause chipping.
 

michiganbuck

Diamond
Joined
Jun 28, 2012
Location
Mt Clemens, Michigan 48035
Milling across with a normal end mill may look not flat because of the lines it makes..but often the finishes is actually flatter than what comes from a mill cutter or a fly cutter because the tram error is not magnified by the length of the cut action.

Good to file test stock to get an idea of how hard it may be. you can just file the cornet bevel if not wanting to nick the stock.
 

CarbideBob

Diamond
Joined
Jan 14, 2007
Location
Flushing/Flint, Michigan
...
TPG's should be illegal. Selling Low End TPG facemills to newbies should
be punishable by having to machine Inconel valve bodies on a desktop mill with
only carbon steel tooling.

Some people really, really do not like these style cutters. :) Perhaps for good reason. They do hammer.
The insert sitting on top is a turning insert. It will fit the pocket but not cut very well.
Can not read the posted feed/speed picture. 1.5 inch tool?
I see some blue and some silver chips so that would be about right in speed if this is where they came from.
Can't see the damage on the gold insert as it out of focus.
Uncurl a chip and measure it's thickness with the tips of your calipers. What is it?
Dead soft steel, any scale?
Are all tools showing the same wear if you stop way early and look at them?
A very general rule is slow down the spindle.
Slow feed rate causes problems with flank wear not chippage. This can add up to too much side pressure than then chips out the top.
Bob
 

Illinoyance

Stainless
Joined
Aug 24, 2015
OP may want to keep the cutter and use it for cutting through scale or flame cut surfaces.He can use the cheapest inserts available: TPU.
 

CarbideBob

Diamond
Joined
Jan 14, 2007
Location
Flushing/Flint, Michigan
OP may want to keep the cutter and use it for cutting through scale or flame cut surfaces.He can use the cheapest inserts available: TPU.
As an opposing view I would not recommend a TPU in this style body.
The negative pressing land will result in a lack of heel clearance if DOC near or greater than tool radius.
As with the above turning insert DOC would need to be less than 1/2 the corner rad size.
I use an insert up sharp and with a T-land for edge strength but where to find those? Cermets? they always have a T-land.
 

4GSR

Diamond
Joined
Jan 25, 2005
Location
Victoria, Texas, USA
I'm old school here and I do have a couple of face mills, if you call them that, that use TPG inserts. I found the TPG324's coated run very good in these face mills I use on my Index 645 mill. I also have couple of face mills that use SEKN42's and all of the variations of, style inserts with 45 deg lead with excellent results. The later would probably work fine for his Rockwell mill. The problem is, it's kind of obsolete nowdays to purchase new. Ken
 

Mtndew

Diamond
Joined
Jun 7, 2012
Location
Michigan
Some people really, really do not like these style cutters. :) Perhaps for good reason.
Because it's not the 80's anymore. Those cutters were pretty much all we had back then for BP work.
Newer styles quickly made the TPG cutters obsolete.
 

Bobw

Diamond
Joined
Feb 8, 2005
Location
Hatch, NM Chile capital of the WORLD
Because it's not the 80's anymore. Those cutters were pretty much all we had back then for BP work.
Newer styles quickly made the TPG cutters obsolete.

And they can be serviceable, IF... IF the inserts are actually laid back
to give some sort of helix to them.. The biggest problem is that the
cheap Chinese ones that every Home Shop Harry buys is that the inserts
are sitting straight up and down.. Essentially straight flute, and that
doesn't work well for anybody. SLAM SLAM SLAM SLAM..

Especially doesn't work well on a less than rigid machine. Compounded
by the non-existent geometry of a TPG to begin with.

Selling a TPG facemill with the inserts sitting straight up and down,
should be flat out illegal.
 

BT Fabrication

Stainless
Joined
Nov 3, 2019
I'm leaning towards feeds and speeds. I think the machine is capable. It's a 780 lb Delta Rockwell machine.

That is a toy size machine, even a regular bridgeport will have chatter issues if they are worn out. that tiny thing probably doesn't feed smooth and id guess jumps and takes out teeth. also too slow just dulls inserts from rubbing. machining, mass is the cats ass.
 








 
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