Milling tool steel

[SPiN Racing]

Hi Guys!

I think I already know the answer.. and its Carbide..... BUt I want to run this by you all first.

SO.
I decided to get started on the Tool holders for the QCTP tonight.

I had previously purchased a chunk of steel... grade zero tool Steel I gather.  It was a drop.. and it is 3" wide by 1" thick, and 26" long.  Sooo I will be cutting a Slot down the length of it.. then dovetail it... then flip it. Cut 1/2" slots across it. Then into the band saw to lop off the individual tool holders... then back into the mill to get holes drilled and tapped.

SO

I tram the head of my mill. 1 thou over a 24" sweep.. I think thats gonna be ok.
I lock this beast of a slab of metal down onto my CLEAN (yes I spent last weekend cleaning the area around the mill and lathe of swarf... 5 Gallon bucket of packed down swarf) Mill surface.
I make sure to get it perfectly square and true with a dial indicator as I traverse the mill.

I chuck up a .75" SIDE MILL... (two flutes GOLD colored cheapy titanium coated Fleabay brand new cutter)
I bring it down with a piece of paper under it, till it JUST touches the work piece.
I adjust the mill stops so the powwer cross feed stops with the end mill JUST outside the work piece on each end.
Move the 5 gallon bucket that is the coolant pump and resevoir over to the mill.. hook it up, so it floods the milling bit nicely.
Hook a drain from the mill table to another clean bucket to catch the used coolant.

Fire up the mill around 1150 RPM.

Bring it over the work... raise the table so it just barely cleans the metal.
then I turn on the coolant, and crank that thing the length of the work. SMoothly and slowish.
I end up with a nice smooth clean evenly cut "channel" in the metal. maybe 2 or 3 thou.

I then raise the mill about 30 thou. ANd decide to see how well its going to cut this steel if I move slow and have flood cooling.

Soooo It cuts... tip gets hot.. little smoke from the WD-40.. but not too bad.. I can still see the tip, and the spray etc. It SOUNDS ok.. nice smooth uniform cutting noise.
I get into the work about 1.5 inches and the sound changes... it begins to go higher pitched.. no chatter.. but it begins to go higher pitched and starts to squeal.. So of course the ultra slow manual feeding I was doing.. I slowed down and backed off.
I attempted to re-start the cutting twice.. and it just squealed and smoked once I very carefuly brought the cutter to the work piece.

I decided 30 THou was too much so I backed off to 15 Thou. Tried again.. and it squealed a TINY bit when I started.. but only a tiny bit.
I slowed down my cut even more so I was barely turning the handle... and I was getting little 1mm chunks of steel uniformly coming off the part, with a small amount of smoke from the coolant.

I then put the power feed on its slowest setting (which isnt moving) and then turned up to the super slow crawl of a speed I was feeding it at.

The table ultra slowly crawled across under the cutter.. uniform sound.. uniform chips, and a tiny tiny amount of smoke from the coolant. The tool bit was bathed in coolant, and staying cool.

Now

The work had a odd shape to the cut.
It had a real smooth center.. and on each side of the cut it had a... prolly 1 or 2 thou step.  -----_______-----

Knowing this wasnt right.. I thought about it as it slowly crawled along... and realised it wasnt the head out of tram.. because that would just cut funny.. leaving a swirl mark of some sort... this wasnt.

After the cutting was done I pulled the tool bit.
Looking at the end.. it had eaten 1/3 of each flute back about 2 thou, but the stronger center was unblemished.

I changed to the other 3/4" cutter I had... a END MILL (4 flutes.. but center cutting also) and moved that baby over to the work.
I tried to make a 5 thou cut.. and it screamed at me like it was going to explode soon as the tip touched the work. Also followed with a HUGE plume of smoke.
I sped the mill up to 1750.. it screamed louder, and more instant smoke.
I slowed it to the slowest speed and it chattered and squealed and smoked.

And yes I am talking move it to the work and ever so slowly slowly slowly slowly touch the work.  (I learned to be careful with a smaller cutter when I started by moving into the work too fast and the small cutter exploding..... so I am very very very careful now... and lucky too thanks)


SOOO

My question.
Should I buy a carbide Side Mill?
As this is a bar of tool steel.. from what I read about Mills.. the Gold colored TiN ones are fine for brass and aluminum.. but once you move to stainless and or tool steel they are complete crap.

Carbide 3/4 Hogging Mill... (Needs to be run at high speed.... high speed being how many RPM?)34 Bucks..
http://www.wttool.com/product-exec/product_id/31610/nm/Carbide_End_Mills_WT_Import_

A Solid Carbide 2 Flute (picture shows 4 flutes) is a bit expensive at 50 Bucks!
http://www.wttool.com/product-exec/product_id/32044/nm/2_Flute_Solid_Carbide_Single_End_Mills_Import_

Or should I simply buy a Indexable tip tool such as this? 16 Bucks, plus inserts..
http://www.wttool.com/product-exec/product_id/33787/nm/Indexable_Carbide_Insert_End_Mills_WT_Import_

Or a set for 50 Bucks
http://www.wttool.com/product-exec/product_id/33822/nm/Indexable_Carbide_Insert_End_Mill_Sets_WT_Import_


Thoughts and opinions appreciated 

[sbwhart]

Hi Spin

Sounds like you're harding the job up with the heat generated from the cutting action, did you have a good flood of coolant on the work.

Coolant does three main things 1:- Keeps the job cool, 2:- Lubricates the cutting face of the tool,
3:- washes away the swarf.

With some material No 1 is the key thing with others its No 2 with other applications its No 3 It sounds like you got a No 1

You should be able to machine tool steel with good quality HSS cutters unless its something special you are trying to cut. With your mill that I know is a quite a good size the depth of cuts you've been taking you should have no trouble, in fact small cuts can be worse that large cut. Cuts of 2 or 3 thou can result in the tool rubbing and generating heat, you have to be bold and go for a deeper cuts.

There's no harm trying a TC cutter but even these will cause trouble if you're not using the right technique

Hope this helps

Stew

[SPiN Racing]

Thanks for the input!!

Yes I moved my coolant over to the mill.. and elevated it, and am dispensing from a 3/32 opening and it has a LOT of coolant coming out. It is WD-40.

Hmm.

More food for thought.   hardening it as I try to cut..... /nod

[sbwhart]

Spin

WD40 may not be the best coolant to use in this application its good for ally and none ferrous stuff but for steel its more usual to use a water soluble cutting oil something like this

http://www.chronos.ltd.uk/acatalog/Chronos_Catalogue_Oils__Lubricants___Adhesives_etc

Cheers

Stew

[bogstandard]

Spin,

Stew is perfectly correct, WD40 is definitely NOT the one to use.

Not only is it no good for ferrous materials, because of the temperatures reached during cutting, it just might burst into flames on the job, and with it being continuously fed with even more WD40, you run the risk of not only your workshop going up, but god forbid, yourself with it.

A good water soluable oil is much better for what you are trying to achieve. One pint of cutting oil, depending on the water/oil ratio mix can give you up to about 100 pints of cutting/coolant fluid. So much cheaper as well.

John

[Darren]

WD40 is definitely NOT the one to use.

Not only is it no good for ferrous materials, because of the temperatures reached during cutting, it just might burst into flames on the job,

That'll be part of my problem then....must get proper coolant sorted....

[Bernd]

SPiN,

Sounds like you were work hardening the tool steel. Try cutting the spindle speed in half and give it a bit more feed, and then try your .030" depth of cut.

With that high spindle speed and taking only a few thou off at a time can work harden the material you are trying to cut.

And of course like Darren said use lots of coolant.

Bernd

[Stilldrillin]

Scott,

My thoughts are......

Or should I simply buy a Indexable tip tool such as this? 16 Bucks, plus inserts..
http://www.wttool.com/product-exec/product_id/33787/nm/Indexable_Carbide_Insert_End_Mills_WT_Import_

2000 rpm.

David.

[SPiN Racing]

 

I Know I know... But I wanted to let you all Know I took everyone's Advice. And went to do some shopping on the cheap.

Pics will be following depending how tired I am when I get home after work.. but I will try to get them up before THursday.

BASICALLY...

I bought the Cutter. .75 Indexable.
Bought a C6 Ti coated little cutter for it.
I bought some Coolant Trico or something.. 30 Dollars for a gallon, mix with water. I did 15 to 1 ratio for heavy milling.
Bought a little water feature pump for 20 bucks.
A couple 90 degree elbows with fitings for soft 1/2 inch hose
3 buckets from Home Depot, and 3 lids.

What I ended up with issss
A bucket with 4 gallons of coolant.
A 3/8 line coming up from it to a fitting in the lid. That runs over to the mill head with a ball valve to control coolant flow.
Then from there down to a small brass fitting I turned with a 1/8 copper line (soldered) running from that and pointing at the cutter.
The cutter 3/4 in the mill..
the coolant runs out the drains in the table to a bucket with lid on each side of the mill for re-adding to the original coolant bucket. (Cheaper than a 80 dollar pump that would be able to pump from the floor to the mill. PLUS I can check the coolant before putting it back in the bucket etc.)

End result.. 1110 RPM, 40 Thou cut, decent feed speed, and not a wisp of steam or heat or anything... just a nice steady snick snick snick snick snick snick.... and a ton of little shin C shaped bits piling up around the groove.
Put it on autofeed and let it eat... for like 20 minutes a pass. (its a long length of steel)
After a slew of passes.. I now have a .4" deep cut .725 wide in the steel.

This Thursday/Friday  between the other projects looming (change rearend in the race car, do some body work to a spot of rust, and re-paint it be end of the weekend April 12) I hope to make a few passes on either side to widen the hole up so I can re-attack with the dovetail cutter I have. (YES.. I will be going extra slow.... but this thing is sooo nice I may talk to SWMBO and see about getting a indexed Dovetail cutter)

[bogstandard]

Nice one Spin.

From your hard going bits in the beginning, you are showing that by taking a little advice really pays off, and are now finding it a lot easier.

You are picking up this machining thing very well. It does get a lot easier the more experience you gain.

Well done

Bogs

[sbwhart]

Hi Scot

Sounds like your cooking on gas  . pleased you got it sorted look forward to seeing progress.

Stew

[Stilldrillin]

 

That`s the way!   

David.

[Darren]

Brill Spin,

I really want to see loads of pic's, the set-up to the finished cut......

I'm bumbling along at the moment making loads of small simple bits getting the "feel" before I move onto something more adventurous.
Confidence is growing quickly, but coolant is looking to be a must, must sort it soon.....

Sounds like you are becoming quite familiar with your machines now 

[bogstandard]

For those in the UK, here is a very good little system that I used on my previous machines.

It did the job with no problems, and is very reasonably priced.

http://www.axminster.co.uk/product.asp?sessionID=QOL&pf_id=21084&name=coolant&user_search=1&sfile=1&jump=0


Bogs

[SPiN Racing]

Thanks for the kind words guys.

Gonna get pics up asap!

Of the cutting, AND the coolant.