Milling for beginners

[Ron LadenParticipant @ronladen17547]

Thanks Jason, appreciated, I can understand that.

[Ron LadenParticipant @ronladen17547]

Posted by JasonB on 01/07/2018 13:19:59:

Sorry I can't agree with that old way of thinking, many "end mills" produced now have centre cutting edges and would now be better named "4-flute milling cutters" as they can plunge cut. Ok this is a rougher but same applies you can plunge, ramp and side cut with 4-flutes

2-flute cutter also tend to cut a lot closer to their nominal size where as a 4-flute can cut over width if it deflects in a heavy cut.

Have a read of part 4 of my series for a bit more info

Not the best photo but the 4-flute on the right will plunge cut

Where do I find your series Jason, I,m probably missing the obvious.

Edited By JasonB on 01/07/2018 13:46:21

[JasonBModerator @jasonb]

In Model Engineers Workshop mag, alternate issues with Neil's Lathework for beginners in the other issues

[NigeParticipant @nige81730]

Ron. The series Jason is referring to runs in the magazine Model Engineering Workshop.

[Gas_mantle.Participant @gas_mantle]

Where do 3 flute end mills fit into all this ?

At the moment none of the 4 flute mills I have are centre cutting so I use a 2 flute for the odd plunge job and 4 flutes for everything else but was curious as to the pros and cons of 3 flutes ?

[Ron LadenParticipant @ronladen17547]

Thanks Jason and Nige

Ron

[JasonBModerator @jasonb]

Posted by Gas_mantle. on 01/07/2018 15:40:42:

Where do 3 flute end mills fit into all this ?

They fit in the middle! Good all rounders particularly in the smaller sizes.

Most of my cutters 1/4 or 6mm and below are 3 flute, I keep a few 2 flute for things like keyways and valve slots and the odd special, material specific or extra long one but as you can see the rest are 3-flute. They work out quite economical on price and I don't see a lot of point in having all sizes in 2 and 4 flute.

Edited By JasonB on 01/07/2018 17:14:59

[Anonymous]

Posted by Gas_mantle. on 01/07/2018 15:40:42:

Where do 3 flute end mills fit into all this ?

At the moment none of the 4 flute mills I have are centre cutting so I use a 2 flute for the odd plunge job and 4 flutes for everything else but was curious as to the pros and cons of 3 flutes ?

Industrially 3 flute cutters are used on aluminium alloys where high feedrates and large chips need large gullets to avoid jamming, but metal removal rates need more that 2 flutes. I don't get too hung up on the number of flutes. I mostly use 3-flute cutters but also have 2 and 4 flute ones. Generally the 2 flute cutters are small (less than 2mm), the 3 flute cutters are uncoated and the 4 flute one are coated and so get used on high carbon and stainless steels.

Despite being centre cutting it is usual to follow a ramp or helical path with centre cutting tools (at least on CNC) as when plunging the centre is, in theory, cutting at zero speed. And hence is quite inefficient.

Another thing worth noting is that some far eastern suppliers don't seem to know how centre cutting cutters work. So the grind pattern on the end is a joke and gives a poor finish.

Andrew

[Ron LadenParticipant @ronladen17547]

I have not looked at mini mills yet in any real detail but a question, do they follow the minilathes in that they are all very similar and coming out of two or three main factories in China. The minilathes (in the same price bracket) dont differ very much in features from one to another, is this the same with the mills.

Ron

Edited By Ron Laden on 18/07/2018 09:37:39

[Neil WyattModerator @neilwyatt]

Generally true, but there is less variation in the mill specifications.

Look for a brushless motor and large table.

Neil

[Ketan SwaliParticipant @ketanswali79440]

Posted by Ron Laden on 18/07/2018 09:37:02:

I have not looked at mini mills yet in any real detail but a question, do they follow the minilathes in that they are all very similar and coming out of two or three main factories in China. The minilathes (in the same price bracket) dont differ very much in features from one to another, is this the same with the mills.

Ron

Edited By Ron Laden on 18/07/2018 09:37:39

Ron,

Mechanically, they are 'broadly' similar. Things start changing mainly in the headstock with type of motors, belt or gear drive. Also, be careful when comparing wattage. Most state input power but WILL NOT say that it is input power.. Machines on our website state OUTPUT power.

The minilathes and minimills no longer come out of two or three main factories. There are plenty of smaller operations selling less than acceptable product via known shopping platforms. It is difficult to explain this to new people entering the hobby without making it sound like sour grapes, and the marketing which supports such products doesn't help either. Also, unfortunately the presumptions you make about 'coming out of the same factories' are quite common. As a result, all the problems start coming to light once the user needs electrical spares…. as they are not all the same.

ARC sells SIEG products, and we field queries on a daily basis – requests for electrical spares to fit a machine which did not come out of the SIEG factory.

Ketan at ARC.

Edited By Ketan Swali on 18/07/2018 10:46:43

Edited By Ketan Swali on 18/07/2018 10:47:45

[Ron LadenParticipant @ronladen17547]

Thanks Ketan,

Belt drive or Gear drive….pros and cons…?

[Ketan SwaliParticipant @ketanswali79440]

Posted by Ron Laden on 18/07/2018 10:52:44:

Thanks Ketan,

Belt drive or Gear drive….pros and cons…?

Realistically, for this size of mill, very little, depending on where you get it from.

Key points: brushless with belt – quieter than anything gear driven.

For gear driven, plastic gears less noisy than metal, but if they break (plastic), more time needed to figure out and change. The plastic gears are 'usually' a fail safe.

Ketan at ARC.

[Ian S CParticipant @iansc]

Not quite on topic, the other night I was reading up on Medding drill presses, they recommend belt drive as best for production drilling over gear drive.

Ian S C

[JasonBModerator @jasonb]

With the next issue of MEW about to hit the virtual door mats of those with a digital subscription here are the videos that show the SX2.7 from ARC being used for some basic cuts with a 4-flute cutter. I used a piece of EN3 steel for these rather than the 6062 aluminium used for the magazine photos, 10mm 4-flute cutter from a budget range as that may be more representative of what a beginner may buy. Cut dry for a clearer view buy would suggest a small amount of something like this to give a better finish and prolong the life of the cutter. If you click "Youtube " along the bottom it will show at a larger size or the icon bottom right for full screen.

Also not all the text was deleted from last months title so no marking out in part 6.

 

 

 

 

 

I hope Neil did not have to reach for the sick bag too much but using a tripod would have been a problem as I needed to show different parts of the machine, also cranking one handed with the camera in the other does not bode well for steady shots.

 

This is the finished steel test piece.

 

 

 

Edited By JasonB on 03/08/2018 07:53:55

[Ron LadenParticipant @ronladen17547]

Thank you Jason, I enjoyed those, very informative.

If as you advise, using a small amount of Maxsyn cutting fluid, would that be neat fluid..?

Regards

Ron

[Ketan SwaliParticipant @ketanswali79440]

Posted by Ron Laden on 03/08/2018 08:20:58:

Thank you Jason, I enjoyed those, very informative.

If as you advise, using a small amount of Maxsyn cutting fluid, would that be neat fluid..?

Regards

Ron

Ron,

Maxsyn is generally to be used 1:20 dilution.

Ketan at ARC.

[JasonBModerator @jasonb]

As Ketan says it's 20:1 on the bottle but I usually mix a small amount a bit stronger around 15:1 and dab a bit on with a brush.

[SillyOldDufferModerator @sillyoldduffer]

Posted by Ron Laden on 03/08/2018 08:20:58:

…

If as you advise, using a small amount of Maxsyn cutting fluid, would that be neat fluid..?

…

May be worth knowing that there are two types of cutting fluid available, those intended to be used neat and those intended to be mixed with water, (which can be used neat).

The 'mix with water' type create an emulsion like milk containing globules of lubricant evenly dispersed in water. Water is exceptionally good at removing heat and preventing cutter damage. Also, a good way of blunting a cutter is to have it re-cut old swarf rather than cut clean metal. An effective way of removing swarf is to wash it away by flooding the cutting area with coolant. Therefore, though it can be dabbed and splashed, emulsions are typically used with a tank, pump, hose, and recovery system.

The neat type are intended for use when heat removal and swarf clearance aren't a priority, like when tapping. The lubricant is applied as needed with a brush or spray.

Some metals like cast-iron and brass are best cut dry. Aluminium is cut with a neat light oil lubricant like paraffin or WD40.

It's not clear in my amateur workshop which approach is 'best':

• Carbide is 'all or nothing' because splashing hot carbide with cold liquid is likely to crack it. You either flood cool carbide or cut dry.
• HSS is less likely to crack and it's safer to apply lubricant with a brush or spray, using the brush at the same time to clear swarf as well as lubricate the work.
• Neat cutting fluid can be used on everything, including Aluminium, which is a convenience.
• The big problem with cutting fluids, especially flood cooling is they make a MESS! I suspect for many reducing mess is the most important consideration. Mostly I potter about doing light machining and don't stress my tools. That means I can get away with a minimalist approach to cooling. All that's normally needed is strategic dabs of lubrication and swarf clearance. Cleaning up is straightforward. Anyone cutting metal more intensively than me would likely put more effort into cooling and cleaning up.

But there are many exceptions. Always lubricate when thread cutting. Despite, not bothering normally, I flood cool my milling machine to protect expensive HSS cutters whenever removing largish amounts of steel.

In an emergency many ordinary substances can be used. Milk, bacon fat, soap and similar all work. Beware of serious disadvantages though. For instance, although Fresh Milk is a good cutting fluid, it decomposes. Apart from the stink, you don't want to get it in a cut – not even in the age of antibiotics. Usually better to buy the real thing.

It's possible I'm 'special'. How do others use cutting fluids?

Dave

[Involute CurveParticipant @involutecurve]

I use flood on both mills, I have flood on both lathes, but 90% of the time run dry, although I do use flood for stainless or deap drilling on the lathe, and Rocol tapping and cutting fluid applied by brush on the drill press and or tapping arm, I also keep a small container of suds next to the grinders, I dip drills, lathe tools ect into it when hand grinding, to stop the fingers getting too hot………ouch

Shaun

[Anonymous]

Posted by SillyOldDuffer on 03/08/2018 10:15:14:

How do others use cutting fluids?

Centre lathe: fitted with flood coolant – mostly turn dry except for drilling steel with HSS, and when parting off

Repetition lathe: fitted with flood coolant – always run flood coolant except for brass and cast iron. All tooling is HSS and I run the tooling hard, after all it is a production machine!

Vertical mill: fitted with flood coolant – almost never use it, as I don't have a drip tray, and it gets thrown everywhere

Horizontal mill: fitted with flood coolant – always use it, except for cast iron, as all cutters are HSS and are working hard

CNC mill: fitted with flood coolant – always use flood coolant, except plastic, brass and cast iron, primarily for washing swarf away, not so worried about cooling.

Cylindrical grinder: fitted with flood coolant – always use flood coolant, seems to give a better finish

I use a multi-purpose soluble oil, Castrol Hysol XF, formulated for hard water areas.

I rarely use lubricants when hand tapping, or machine tapping on the vertical mill. For coarse threads or tricky materials like stainless steel or bronze I use Rocol RTD. Works well but is a PITA to remove.

Dabbing coolant on with a brush is a complete waste of time. It doesn't really cool or lubricate and just creates a sticky mess. If you need to get rid of swarf when milling use cheap brushes dry.

There are stories about soluble oils going off. That may have been true in the past with natural oils, but is certainly not true of the newer formulations. My coolant can sit in the tanks for months or even years and never seems to go off. Mind you I do have a poor sense of smell.

Andrew

[Neil WyattModerator @neilwyatt]

Posted by SillyOldDuffer on 03/08/2018 10:15:14:

• Carbide is 'all or nothing' because splashing hot carbide with cold liquid is likely to crack it. You either flood cool carbide or cut dry.

I've never had problems with brush application of neat cutting fluid to carbide tooling. Stop start dribbling of suds might be riskier.

[MuzzerParticipant @muzzer]

Don't see the point applying coolant by brush to carbide tooling (or any, other than hand tapping for that matter). Seems to be essential behaviour in the US – but on this side of the pond?

[Neil WyattModerator @neilwyatt]

Posted by JasonB on 03/08/2018 07:27:16:

I hope Neil did not have to reach for the sick bag too much

He appreciates your concern

The problem is not a moving camera, it's combining a moiving camera with automatic stabilisationon interior shots so it causes weird perspective changes.

[BazyleParticipant @bazyle]

School machines were fitted with flood coolant because it made more profit and the salesman justified it as training for industrial practice which was true. When these machines got sold off amateurs started to get the impression that it was necessary. Before that virtually no modellers used flood, just a can and brush or a simple drip as shown in some ME articles to be 'advanced'.
When the company I was at still had about 50 machinists in the prototype section they never used flood (nor any lubrication on Al) because like sensible hobbyists they were not in a tearing hurry.

Soluble oils still evaporate water and can stain/rust when not in regular use. Do you really want to spray your workshop with a hosepipe? I think there are some waterless products for use in volume on CNC machines if you really want flood.

[Author]

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