Seeking high-precision milling machine for mild steel, better than Proxxon MF70(!)

[Bented]

Paul is right, Posting one's desires , does not make such a reality !

Your chain has been pulled, roll with it.

[tom_d]

Other than the build quality where, specifically, is it lacking? Is it possible to modify the existing Proxxon MF70 mill so it more closely resembles the desired mill performance? When you have your own shop you can make things, and you can make things better.

[Jim Stewart]

LOL Apr 1.

Bingo!

[junkaddict]

It should make coffee too.

[ship69]

Nope my question was serious.

Thanks for all your replies & suggestion folks. I shall go through them in detail properly when I have time.

My central point is tha tthe Proxxon MF 70 weights just 7Kg (15lbs), and goes up to 20,000 rpm (faster than I need). Its motor rather weak though at just 100watts, and whilst an over-priced brand, and although it is quite well made in some ways there are lots of hideous weaknesses - Proxxon just never quite finished doing a decent job of it. Even the spindle is said to be off true by 0.003inches.

But what I don't understand is why, with gearing, you can't get a properly powerful motor (e.g. 750+ watts) to go essentially any speed you like? It's called a gearbox. They work well on things like cars/automobiles. Or probably more durable in the event of sudden stops would be pulleys somewhere in the power chain.

Look, even my bosch hand-held hammer drill is 750 watts, and it only cost about GBP 65.00 and it does 3000 rpm, WITHOUT any gear or pulleys. Why are all these mills so under-powered? I know it's basically just a motor but it's light too - only about 1.5 Kg.

I'm obviously missing something, but what?


PS I am new to all this, and obviously I don't know what the heck I'm talking about, but all the machines that I've seen don't look like the've had a facelift or a redesign since the 1950s!
Look, I don't want to be rude nor inflammatory... but to some extent do I have a point?!
Seriously if I am to spend say GBP500 to 1000... has any of this technology significantly improved since the last century?!

[David Powell]

HI, I see your frustration, but your requirements cannot easily be met , given the weight restriction you specify
. I own, and use daily an Emco FB2 mill and an Atlas Horizontal mill. Both of these are , nominally bench top machines and could be retrofitted with high speed spindles, indeed I have such a spindle ready to adapt But they are well over 100lbs.
I know of, and have seen some small Swiss made machines which might be of interest.
Perhaps the Sherline and or Taig machines could be of use to you, many users speak highly of them.
You could turn your requirements ino a lifetime adventure to create a machine to meet your needs
Have fun Work safe, Regards David Powell.

[thin-woodsman]

But what I don't understand is why, with gearing, you can't get a properly powerful motor (e.g. 750+ watts) to go essentially any speed you like? It's called a gearbox. They work well on things like cars/automobiles.

But it's not *just* the gear box. You can hook up a 10 HP motor to a Sherline or Taig, lower it down to 100 RPM and let 'er rip. The frame of the mill will get twisted out of shape, destroying the mill instead of stalling the motor when the load is too high.

To continue your example of a hammer drill, take that hammer drill, load a 1/4" (6mm I think) stub HSS drill bit in it, and attempt to drill a hole in 1/2" structural steel. As soon as the drill enters the hole, it will catch, and instead of the drill bit turning the handle will turn with equivalent force. Depending on your grip strength and bone structure, you will either walk away somewhat dazed at the speed of it all, or end up in the hospital with a wrist injury. In this scenario, you are the frame of the mill, the drill is the motor, and you have just damaged or destroyed the frame of the mill by applying too powerful of a motor.

Metal takes a lot of force to cut, and that force requires rigidity. This can be overcome to some extent by taking many light cuts, at high speeds, and that is what these lighter machines are built for, but they end up getting used for softer materials because nobody wants to wait five days to remove 1/8" from some steel. The natural endpoint of this is the CNC router, which is *for* wood but can be used on aluminum (possibly even steel, with a light enough cut and a rigid enough frame).

It is the material cutting forces that require the power, and the power that requires the rigidity. The "material" bit is key: wood will yield easily to a metal bit, and stone will crumble under a carbide bit, but metal is basically shaved by a metal bit (like a wood plane or router), and the bigger the shavings, the more power is required.

[Rich Carlstedt]

........................................has any of this technology significantly improved since the last century?!

Yes, and No, depending on what you want.?
Machine tool technology has expanded tremendously with CNC Machines being the fore-runner
Manual Milling machines have not...and the simple reason---no call for their development !
Motor development has expanded with DC drives and Frequency Controls , but they cost money $$
and would not be used for small , seldom sold machines
The type of machine you are looking for is classified as clock/watch making machines.
Guess what ? The world has switched to Digital (electronic) clocks and watches so again -
there is no need or wants for further improvements in the micro machining area !
EXCEPT
the realization that VERY exacting material control and cutting- is possible with CNC and Mass.
Ergo...there may be a esoteric mill out there that can do such work as you want, but it will not be cheap.
Check Switzerland and see what they might have from the past..but no one else has your needs I believe
My suggestion:
I had a friend who had a Unimat lathe in a suitcase so he could make model parts when traveling.
You may want one of those with a milling attachment ( if made ?) or have one made for it.

Rich

[Mcgyver]

Seriously if I am to spend say GBP500 to 1000... has any of this technology significantly improved since the last century?!

Unfortunately the universe doesn't owe us a super mill you can carry under your arm and buy for less than 1000. Machine tools are as good as they can be given the cost to manufacture and the market's needs/ability to pay.

Some of the small swiss equipment would come close, but a lot (most, all?) isn't made anymore and vises can sell for more than your budget. Its bit like asking for a car that'll carry the three kids and their hockey bags, top speed of 300 mph, 10 second quarter mile and has to sell for under 30,000. Why not say 40,000 rpm and be even more frustrated? The parameters are not realistic in the context of machines in the physical world

For example the little Fehlmann mills would give you the accuracy. But they're say $40,000 and still only 6000 rpm and a hefty 900 kg (with stand). Its just what it takes to super performance in a new machine...just like cars, high performance and quality is really expensive.

I would suggest to break down what you actually need it to do. For example, if the task is a 0.5mm hole, you do not need 20,000 rpm despite the theoretical you might have read, e.g. watchmakers make holes a lot smaller than that at 1-2000 rpm....heck you could do it with a pinvise if patient enough. If any of what you need is truly not doable without really fancy stuff, outsource that part.

milling is not a precision operation. Maybe look something like servo drill press for drilling capability and if you need more accuracy than a run of mill mill can delivery, outsource it to be ground, learn how to lap or scrape, and so on. Lots of ways to skin the cat.

[junkaddict]

Before getting a full sized mill, I had a Seig X2. 57KG. I was surprised at just how much flex was in the machine when applying cutting forces. Did OK with small cuts and non ferrous material. You say larger work also. Mass and rigidity go hand in hand. I don't think anything in the weight range you specify is possible without some serious exotic materials and creative engineering.

[small.planes]

MF70 based, 750W spindle, upto 24k rpm. Wouldn’t want to use it by hand, but fortunately I cnc’d it. High spindle speeds need a consistent feed especially for the small diameter endmills.
Just upgrading the spindle was a major improvement over the stock Proxxon one. It no longer snaps small endmills. Without the enclosure you get tiny chips *everywhere*.

[small.planes]

Test cut in cold rolled steel, 2mm (IIRC) carbide endmill, something like 12krpm.

[BCRider]

Looking at the Proxxon MF70 you mentioned going up to a Taig or Sherline would be a step up in size. And with proper tuning and setup of all the parts I think it would give you the level of accuracy you're after. But it would only do marginally larger parts than the Proxxon. Both of these being more on par with the slightly bigger Proxxon other than you have some more control over the speed due to the more open pulley drive setups on those two options. But I seriously doubt that the bearings in the head stocks of either option would tolerate speeds up around 10K for very long without overheating or skidding the bearings and ruining them. For that sort of speed range if used consistently I think you'd need to consider a different lubricating system for the high speed end of things. The good news is that the head stocks are low enough in cost that buying and setting up an extra one for use with a different lubrication system and use it for all the higher RPM range jobs would not be out of the question.

There's nothing at all within the weight range outside of these which are only marginally bigger than the MF70 other than the Proxxon FF230. The next bigger machine I can find is the Grizzly G8689 4" x 16" Mini Mill. But with a 150lb shipping weight it will still be well over 100 lbs or 50Kg. And I just don't see anything else around which is new and between the Taig/Sherline size and this.

You used Kg for your weights. If you're located in Europe then some of the local machine suppliers might have some other table top options. But all the smallest asian import machines seem to start at up around 100 to 120lbs or 45Kg.

[BCRider]

Small planes, what was the bigger advantage of the new head that made the difference? I can see two things being an issue. First is for small carbide cutters any play or vibration in the bearings at all would be disastrous. And second would be any but the most microscopic of runout in holding the tiny tooling.

[hoof]

I think an Aciera F1 gets some of the requirements. Really nice but very pricey.