Milling machine speed range

[Christopher KnightParticipant @christopherknight]

I wish to buy a small milling machine and am considering a Wabeco (on account of the hoped-for benefits of German Quality). I am a bit puzzled by their product offering of a high speed machine – at considerably more cost than the basic model.

 

Can anyone explain why 7500rpm max of the higher speed machine should be useful versus the 3000rpm max of the lower speed machine? I would have guessed that most milling is done at substantially lower speeds than either of these, except when using very small cutter sizes.

[Christopher KnightParticipant @christopherknight]

[Clive HartlandParticipant @clivehartland94829]

Christopher, the high speed machines are offered with X,Y,Z drives and can be used for engraving.

They can also be used manually.

Engraving cutters need high revs to cut efficiently.

I would suggest asking them for a catalogue which explains the various set ups with these machines.

By the way, I suggest you buy one with a long table, the 1200 series is a very short table length.

Otherwise they seem to be very good machines and far better mechanicly and technically than some of the Oriental offerings.

I agree the prices are on the high side but they recently reduced the prices by about £239 on one of them.

 

Clive

[Christopher KnightParticipant @christopherknight]

Thanks for the response Clive. I take your point about the size of the table – the basic one is pretty short indeed.

[Roderick JenkinsParticipant @roderickjenkins93242]

Christopher,

Tubal Cain in “Milling Operations in the Lathe” quotes industrial speeds in aluminium greater than 3000rpm for endmills of smaller than 5/16″ and for slot drills smaller than 3/8″ for HSS cutters. TC cutters, especially if coated, require even greater speeds. These sizes are not that small for model engineering. My mill has a top speed of 2000rpm and I have been looking at ways to increase this since feed rates can get painfully slow at low spindle speeds.

cheers,

Rod

[Christopher KnightParticipant @christopherknight]

Rod, thanks for your reply. you make a good point and it is useful to hear your experience.

 

Chris

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

Hi Roderick J ,

 

A quite common piece of engineering equipment , available commercially once , is the in line speed increaser . This consists of a standard shank , a small epicyclic gearbox and a small milling chuck or plain taper socket on the end . Can be arranged to give berween 3:1 and 10:1 speed increase .

 

Poor ones have everything stacked end on end whereas the clever ones have a shank and (relatively) big body in one piece with all the works nested inside giving much better rigidity .

 

At least one has been described for DIY construction in the magazines .

 

MW

Edited By MICHAEL WILLIAMS on 01/01/2012 16:58:49

[David LittlewoodParticipant @davidlittlewood51847]

Roderick,

 

You may or may not be into making tooling, but there is a kit for a speed increaser available here – but note it reverses the rotation, you will need to fit a reversing switch to your motor.

 

David

[blowlampParticipant @blowlamp]

I discussed the topic of high speed spindles on another forum last week and in particular of one I’ve designed and put together. So to avoid repeating what I’ve already said, here’s a link http://www.cambam.co.uk/forum/index.php?topic=2207.0 I hope it’s of some use.

 

 

Martin.

[JonParticipant @jon]

Dont just assume its German its quality, there are many things they produce of sub standard quality, those mills being one of them.

 

Having wasted £4500 F1210E or 1220E? 10 yr ago best thing we did was get £1100 for it 8 yrs ago and put the dosh towards a cheap chinese Super Lux mill for price of the Lux. At least we could actually do something.

 

Ok for wood and plastics, thats about its limitations unless you want to spend all day for what a diy rated chinese mill would do in 10 mins at 25% of the price.

The main problem is the upright vertical column visually flexing with menial cuts in steel. Cost us an arm and leg in broken cutters £30 a pop due to the flex which in turn created severe bounce.

The supplied grossly expensive ER collets didnt hold either.

The general build is good but useless with that humongous quill bounce.

 

 

[Roderick JenkinsParticipant @roderickjenkins93242]

Apologies to Christopher, I didn’t mean to hijack the thread.

 

Michael and David,

I have actually had a go at making Dick Stephens speed increaser. So far I haven’t been successful in reducing the run-out to acceptable levels. I’ve put it to one side for the moment, I’m going to try machining the input and output ends on their own bearings when I can work out how to do it.

 

cheers,

 

Rod

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

R J :

 

The Dick Stephens speed increaser will always be problematic to make accurately because of the way it is designed . With meticulous work it will turn out ok but really there are better ways to go .

 

If you want to use cutters 1/4 ” and smaller including engraving cutters it is far easier to make a new small free running cutter head for the purpose and just fit it to a tool shank and drive from an auxilliary small motor via round belt . If you put part of the spindle and top bearing inside the tool shank the whole thing can be very short and rigid indeed . Even if your tool shank is too small to do this the set up is still much more rigid and short than the Stephens in line speed increaser and ten times easier to make .

 

MW

Edited By MICHAEL WILLIAMS on 02/01/2012 11:59:06

[Christopher KnightParticipant @christopherknight]

Jon,

That’s a pretty damning view of the thing and the first negative review I have found online.

 

I shall definitely have a look at it but hopefully get the importer to demo a hefty cut or three.

 

I wonder if the machine has been upgraded since you had yours?

 

Chris

[blowlampParticipant @blowlamp]

Posted by MICHAEL WILLIAMS on 02/01/2012 11:51:09:

R J :

 

 

…If you want to use cutters 1/4 ” and smaller including engraving cutters it is far easier to make a new small free running cutter head for the purpose and just fit it to a tool shank and drive from an auxilliary small motor via round belt . If you put part of the spindle and top bearing inside the tool shank the whole thing can be very short and rigid indeed . Even if your tool shank is too small to do this the set up is still much more rigid and short than the Stephens in line speed increaser and ten times easier to make .

 

MW

Edited By MICHAEL WILLIAMS on 02/01/2012 11:59:06

Agreed Michael. In fact just like the one I made and posted a link to a few messages back

 

Martin.

[JasonBModerator @jasonb]

Chris, the Lux is a far more substantial machine and I would expect it to take a much heavier cut. By Jon’s use of “us” and “we” it sounds like it was being used commercially where time is money whereas most of us hobby machinists are happy to take a few more passes at a job.

 

A lot depends on what you want to make, you say you want to do stationary engines, well apart from the main few castings the majority of the work will be very small and the Wabeco will cope with ease and the bigger bits just take your time. If you were thinking of using it on say a 3″ or 4″ traction engine that would be another matter.

 

J

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

Hi Blowlamp ,

 

Had a look at your spindle – seems to be based on sound principles and I expect it works well . I see that you have built the motor drive onto the cutter head itself .

In larger sizes I would do the same and in smaller sizes I would use detached motor and belt drive .

 

Regarding some of the types of milling machines under discussion (by various makers) :

 

What you are actually looking in many cases at is a ponderous overhanging weight cantilevered off a short slide mounted on a narrow and unsupported vertical slideway further cantilevered off the base unit and attached by means barely adequate for a shelf bracket .

 

MW

Edited By MICHAEL WILLIAMS on 02/01/2012 14:03:41

[JasonBModerator @jasonb]

Well if work like this can be produced on a 1210E then I’d be happy to pile a few tins of beans on that shelf.

 

As the saying goes its not what you have got its what you can do with it.

 

J

[Christopher KnightParticipant @christopherknight]

Jason,

Thanks for your points and the link. I’d be happy to be able to do that standard of work with anything!

 

Chris

[JonParticipant @jon]

The dongled cnc 1210E was intentionally bought 2002 to rough out an iregular shape from 5mm thick flat, ground one side and ending 3.3mm thick finished after polishing, nothing trick allowing some hand finishing to size. Approx length 4″x 1 3/4 wide. Max mild steel removal inc a grind of one side 1.7mm with coolant!

Was presentable on parts 1/2″ longx 5/16″ with sub 5mm cutters.

 

Theres a certain hush hush tight lip which has happened several times with other so called top quality goods from that country, whats more they dont like being told same as Japan.

 

By all means try the exact machine you intend to buy. I wouldnt want anyone to waste money.

Get him to put a cut on mild steel 1mm+ with 12mm/1/2″ cutter and make sure he dont take all day over the feed rate. Watch the upright column and head, listen for the cut or note change even if it only happens once.

[Fowlers FuryParticipant @fowlersfury]

I purchased a 1290E Wabeco mill a few years ago. It had the round vertical column and was atrocious for flexing under any sort of cutting. Consequently I contemplated what sort of 2nd hand price I might get for it in order to buy a Chinese job with decent vertical column with dovetail slides etc. However I then discovered I could buy such a column from Wabeco – expensive but I’d at least keep all the table clamps, DRO stuff etc I’d fitted.

When this column was installed, it was quite a transformation and for a small mill, it gets very regular use now for the 5″ loco under construction.

 

However . . . . my opinion of the German electrics is another matter

After some use the motor began to ‘stutter’ and a strip down revealed that the pcb is exposed to the flying carbon particles abraded from the motor brushes and this caused tracking. The pcb needed thorough cleaning and then encasing in polythene sheet. In addition I fiited a pc case fan just in line with the motor brushes to extract the carbon particles & add some cooling.

Shortly after this, the electrics started to play up again and this time the linear pot which controls the speed had failed. I purchaed a replacement from Maplins but this caused new problems. After more aggravation I found it necessary to use a log pot rather than a linear one and this is a continued annoyance when changing speed. (I’m no expert on electronics so don’t understand about the linear/log potentiometer issue).

A little later the plastic knob on the pot literally fell to bits, but a better replacement was easy.

 

Another irritation is the X axis locking key for the table. If you happen to leave this in the down position it will shear off or bend when advancing the table in the Y direction.

 

Yet despite the trials & tribulations, mechanically the mill is superb. Just comparing the feel of the X, Y & Z handwheels to those on Chinese mills at exhibitions shows it’s a quality product IMHO.

 

 

[Ady1Participant @ady1]

My old lathe cant do no more than 500 rpm, but it is very stiff for milling work.

 

I’ve found that “higher” speeds often create too much heat and can damage the cutter when a lot of work is being done.

Presumably very high speeds would do best with a coolant system.

 

For things like aluminium using the backgear has worked best for me.

The unit can munch an entire t-slot through an aluminium plate in a single pass because using a slower speed like 50 rpm does not create too much heat, and the stiffness/torque can do the work.

 

There certainly seems to be a trend towards “high speed” equipment but it should be borne in mind that these speeds can generate an amazing amount of heat, especially if its a big job.

 

I have also found that 6-8mm max is the best size for my hobby machine when lots of work needs doing, strength and torque.

A two flute cutter is best if you only have a bog standard grinding wheel.

The closer to the centreline the cutter is…the higher the torque.

A t-slot cutter rapidly loses torque because of it’s profile, the teeth are a very long way away from the very high torque zone along the centreline

 

 

Edited By Ady1 on 05/01/2012 00:24:21

[JasonBModerator @jasonb]

Ady, I’d said the same thing to Chris via PM, I would be more interested in the lower speed than the top end particularly when doing large intermittant cuts like the curve under a chimney saddle.

 

And as you say high speeds on alloy need something to stop the metal welding to the tool and to clear the swarf.

 

J

[Ady1Participant @ady1]

This is an old unimat milling table project of mine.

A first attempt by an amateur at cutting t-slots straight through a solid 12.5mm aluminium plate

 

The upper and lower t-slots are rough because they were done at higher speeds and had heat issues, vibration marks, sticky swarf and needed lubricating.

Non stop hassle which needed constant care and attention.

The lower slot was done on a unimat…lol, silly me, took about 3 days.

the upper was on the Drummond and was more controlled but still had the usual high speed issues which plague working with aluminium.

 

So I employed the family braincell and tried a different approach

The t-slot right through the middle of the plate on the left hand side was a complete doddle, done in a single pass with no lubrication on the backgear, and the finish was luvvly.

 

At amateur levels I find that stiffness and torque are far more user friendly, especially for longer jobs if the machine is doing a lot of work and heat becomes a major factor.

Edited By Ady1 on 05/01/2012 09:38:42

[Ady1Participant @ady1]

Here’s a more detailed photo, showing the incredible skills of an amateur.

I stopped at that point, having finally sussed the major hurdle of overcoming those high speed heat problems

 

Major heat issues on the right with the “high speed” unimat (1000rpm? and oh boy was that a nightmare job)

 

Moderate heat issues on the left with the drummond on “high speed”(4-500rpm)

 

Both attempts also needed lots of messy lubrication and there was a lot of stop/start procedures when the heat buildup got too high, jammed cutter issues etc.

 

Zero heat problems in the middle with the backgear and no messy lubrication required, only some milling marks(50 rpm), and the entire job was all done in a single easy peasy pass.

 

Sussed at last. phew!

 

Edited By Ady1 on 05/01/2012 10:15:34

Edited By Ady1 on 05/01/2012 10:31:40

[Ady1Participant @ady1]

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