milling machine issue

Hi I have brought a new warco WM18 mill but i'm having a few teething problems (partly because of best changlish and partly re-learning possibly lacking a bit of bravery to!).

firstly when i'm trying to take a cut in the z axis i can only take out about .5mm not too much of a problem but its just lots of little cuts.

if i dare to attempt to take more out it feels/sounds like the machine is going pull its self out the ground!

the other issue im having is when taking a cut some times it would appear that the z axis is dropping half way through a cut but I think this a temperature issue i only say this as after it has happened the tool is too hot to touch. short of water cooling (funds wont allow just yet) is there anything else i can try?

im using a 4 flute 16mm HSS cutter running at 1500RPM (spindel speed). iv'e tried locking the Z axis and the quill feed but it dosen't seem to be working.

any help would be appreciated

Thanks

Phil

Sounds like you need a refund......

the spindle speed is ok for aluminium 385 for steel with a 4 flute hiss cutter

Edited By Zan on 11/07/2019 15:08:41

You need to give us a bit more information. Are you cutting using the full width of the cutter? Profiling or surfacing? Are you cutting free cutting mild steel, some unknown scrap, or a known alloy of aluminium. For mild steel 1500 rpm is way too fast for an HSS endmill and would result in a blunted and hot cutter.

Russell

im cutting using half the diameter of the cutter so 8mm. I'm using aluminium 6063-T6.

bellow is a rough representation of the part that I'm trying to reproduce. currently I'm just trying to produce the L shape before i start trying to deal with the centre cut.

I'll check the draw bar as soon as i get home but I suspect it is tight. would using collets help with this or just stick to the chuck that came fitted?

Thanks again!

Are you using a jacobs chuck? Are you climb milling? Those could potentially be your issues.

I would go for direct R8 collets with that 16mm endmill and see how it goes.

What is the chuck you are using? If it is a drill chuck, then it is for drilling only, not for holding milling cutters.

Cutting using the Z axis with a 16mm four flute end mill is not recommended. The Z should be locked and the X and Y should be used.

Most, but not all four flute end mills are not intended for end cutting and will not like plunging more then 1mm.

I'm sure one of the members could recommend a book on how to use a mill.

OK. Do you have any build up of aluminium on the cutting edge? If so you might need to lubricate with a little parafin or WD40 to prevent it. Feed rate should be quite fast, about 5 mm/second. The cutter needs to be really sharp. I find cutters designed for aluminium work much better than general purpose ones.

I doubt that your problem is a result of the heating but the heating is a result of your cutting problem.

Rigidity everywhere is important.

Hope that helps a lit.

Russell

Is the cutter sharp? is it coated? As it should not be getting hot at that speed in aluminium with only a 0.5mm DOC.

To reduce the top of that part down to height I would be setting the cutter to the full height you need to remove and then taking passes of 3-5mm across the work, why use just the end of the cutter when you have paid for the whole length.

Lock the head to the column and lock the quill to the head and lock the axis you are not feeding along. Bit of paraffin or WD40 will also help

I know of a good series about milling for beginners!

i will fit the collet when i get home then!

yes i did find WD-40 'borrowed' from work helped

if you have the name of that series i wouldn't mind a read but i suspect i have the book and glossed over a couple of sections. ill blame the wife's kitchen!

Thanks ill keep you all posted!

Just in case it's the chuck, here's a photo of a small Jacobs Chuck mounted in an ER32 Milling Chuck.

The Jacobs chuck (silver with teeth) is for holding twist drills; Jacobs don't resist sideways forces well and are really only good for drilling holes. In this photo I have the Jacobs gripped in an ER32 collet chuck; collets are good for sideways forces. You should be using a collet chuck like the upper one.

As mentioned the rpm is high for HSS and Aluminium and there's a good chance you have aluminium swarf welded to one or more of the cutting edges. Not good! Don't worry you should be able to scrape it off with a screwdriver, or dissolve it in Caustic Soda solution. Lubrication is very helpful with Aluminium; a light oil like paraffin or WD40 not water. Doesn't need flooding, just regular splashing with a brush. Also, make sure the cutting area is kept clear of swarf. Recutting swarf is bad too, and will amplify any looseness in the set-up.

The manual that comes with the machine is a simple overview of the various controls etc, what it is, not how to use it.  Jason mentioned his beginners series currently running in Model Engineering Workshop - recommended, otherwise a book like Harold Hall's 'Milling' - Workshop Series No 35, will help and the internet is your friend!

Last point, do you mean cutting downwards by Z-axis? If so 4-flute cutters are complete poo at that because they choke on their own swarf. Four flutes are for slicing shelves or sideways along an edge, not for cutting an enclosed slot. A 2 flute cutter (aka slot drill) is needed for that job.

Possibly there's something wrong with the mill, more likely you're just at Learner Driver stage. It takes a while to get used to milling machines and it's well worth doing some swotting and experimentation. The forum is always good for advice.

Hours of fun ahead!

Dave

Edited By SillyOldDuffer on 11/07/2019 17:12:09

+1 for everyone who says Do NOT use a drill chuck for milling. If thinks are moving that is at least part of your problem. use a proper collet system. ER is my choice, FWIW

!500 rpm on a 16mm cutter sounds much to fast. having reduced your cutting speed to below 100 f p m, your feed rate should not exceed 0.002"/rev (0.05 mm / rev) And these are under ideal conditions.

Your fee direction should be so that the the workpiece " collides" head on with the cutter tooth.r

Climb milling is likely to drag the cutter into the work, and could result in damage to both.

Depth of cut should not exceed cutter diameter / 4. i e. don't try to plunge down to produce a 16 mm wide slot.  For that you should use a slot drill.  Most End Mills do not cut to the centre, some do.  Cutting a shelf 4mm wide is working things hard for a small hobby machine. 

Examine your cutter carefully, if you have overheated it, it may now be damaged and blunted. If so, it will never cut properly, until resharpened.

These figure are approximate. Each set up, machine, cutter, machine condition, rigidity of the machine and set up will all vary, and so must the feeds and speeds that you use. A depth of cut that works well with a workpiece gripped by the full depth of the vice jaws could rip the job out if gripped by just the top of the jaws. A flimsy vice cannot withstand the loads that a good one will. Nor will your work be as accurate.

Silk purses, sow's ears and all that.

Jason is being modest.

You need to read all of his his series of articles in M E W on "Milling for Beginners" You will learn a lot from it, so find the back numbers, to read from the start.

Hopefully, you will have better experiences in the future.

Howard

Edited By Howard Lewis on 11/07/2019 17:20:22

There is a loose end here. Warco say the WM18 is supplied with a 13mm drill chuck. The cutter was 16mm.

And what was shown, as the work piece would not be produced by plunging in an End Mill.

It would be better to use a slightly smaller diameter End Mill to rough out the slot, and then to finish it with a slot drill, by traverse feeding both, rather than plunging.

Seems like the wrong method with the wrong tools for the intended task.

Have a rethink, and don't be overambitious before trying again!

Howard

Phil said he was machining the top surface down to the reduced height so tool was fine for that use. Also that slot can't be finished with a slot drill it has radius corners soeither needs a radius corner mill or roughing out and finishing with a ball nose cutter.

As to 16mm cutter in a 13mm drill chuck it could be a reduced shank cutter, I have some 1/2" ones with 3/8" shank.

May seem a daft question, but is the spindle running in the correct direction? I only say this as I got a severe dressing down for wrecking a face mill by running it in reverse when I was an apprentice 39 years ago. Something I will never forget.