Proxxon milling machine motor upgrade

Having experienced the motor get very hot on my FF400 which I think is a common problem in all but very light us, I wondered if anyone has any suggestions to a suitable motor upgrade?

Having experienced the difference between single phase and 3 phase vfd this was my first thought. However I am not sure a suitable motor exists eg size, power & price so I was thinking of variable dc and perhaps a used treadmill motor.

What are other peoples opinions and suggestions?

Difficult to find this mill. Seach for Proxxon FF400 brings up a fine downfeed accessory. On another thread started by someone whose table saw motor had just blown I said that Proxxon products seemed "over-priced and under-engineered" (based on my experience). What you describe sounds like another manifestation of this. Could you post a photo?

Generally many of the small mills based on the "X1" platform use DC motors and AFAIK they aren't known for running hot though the controller boards seem rather fragile. Depending on the design of the mill fitting a 3 phase induction motor could be difficult as they tend to be rather large compared to DC motors of the same power.

It looks about the same size as a Unimat3 so don't expect it to take heavy cuts and if like the U3 you need to let it rest for 2mins in every 10. Sharp cutters are also a must.

Edited By JasonB on 15/08/2020 10:25:18

I can't find the FF400 either. Can you post some photos Jon? Howto here.

I think it's a micromill with a small high rpm motor, intended for light modelling: OO-gauge, Radio Control, PCB-work, dolls houses, clocks etc rather than 3.5" locos or bigger. Not a metal muncher.

The problem with up-motoring machines is the risk that the available power becomes unwise relative to the machines rigidity, bearings, belts, and gears. A micromill that whizzes through Brass with 200-300W to a small cutter at 4000rpm will probably flex like a ripe banana when asked to push a 10mm 4 flute cutter through steel with a 500W motor. Gears are likely to strip, belts snap, lead-screws wear and other damage. It's akin to me dropping a 3litre NOX boosted engine into my urban hatchback without bothering to upgrade the wheels, radiator, oil pump, suspension, brakes, clutch and gearbox etc.

I suspect Jon doesn't really want an FF400 with a bigger motor, he needs a bigger milling machine!

Dave

Edited By SillyOldDuffer on 15/08/2020 10:52:08

If the machine is the same as that posted by Jason above. Then this was originally designed by the Sakai Camera Company as the MM 140, this machine came with an Induction motor. It should not suffer from the duty cycle of the U3.

Record Powerline also distributed these machines when the range was on the market under the Toyo brand.

Manix bought the production rights to the Sakai range of machines. I also think Proxxon did as well, but they have made some changes to the original design with a different table. They have also made changes to the Sakai lathes in their range.

Regards

Gray,

Edited By Graham Meek on 15/08/2020 12:03:51

Yes machine is the same as posted pic by jason, not a great amount of power only 400w. However it is a lot bigger than a mini mill so I would expect it to to do a bit more than 00 gauge.

The travel on the table is 200mm X 100mm Y 100mm Z or there abouts.

I have yet to put it to any serious tests, I tried milling some mild steel with some cheap hss router bits. It got very hot!

As an aside the dial on the quill to the left doesnt seem to do anything and its not documented in the manual any ideas?

This may inform the advisors : **LINK**

https://www.manualslib.com/manual/1204863/Proxxon-Ff-400.html?page=12#manual

MichaelG.

.

Personally, I would look for a suitable 3-phase motor and VFD ... which is where you came-in, jon

There should be a shaft on the fine feed attachment that you "push in", to engage the pinion shaft that operates the Quill. You may need to turn the fine feed handwheel while pressing on this shaft. The Fine feed will not operate until the Dog-Clutch has aligned and engaged with the pinion shaft.

Regards

Gray,

Thanks Graham,

I will have a good look on the mill for the clutch mechanism.

Also thank you Michael for the manual link.

All I need to figure out now is whether to go for vfd 3phase or dc variable voltage? The later could be cheaper and simpler electronically.

Jon,

I have as my little mill what's termed a micro mill which is about the same size, it's badged from various suppliers like machine mart, Chester, Arc ET in various forms. That was DC and the motor used to get hot after about half hour of moderate duty. I burnt one out and then blew the control board ( doing stuff too big for it I may add but that's another story!). Motor cost was about £80, board I think was going to be about £60 but I didn't bother! Found a 3 ph motor with a suitable flange from inverter drive supermarket I think it was for £40 inc and combined that with a VFD from a source that is now unmentionable on here and a make that brings howls of derision and horror! Transformed the machine, I can now run it for hours without it getting warm and it still gets used for stuff too big for it but now without complaint!

My advice would be 3 ph and VFD.

Paul.

Thanks Paul

I must admit I didn't know whether variable dc was any good so it is great to here other peoples experience, I have heard of people using salvaged treadmill motors to power their machinery.

Regarding the VFD in my limited experience it worked out well with the speed 10, previously it had a bog standard single phase ac motor. This would get extremly as hot it was used to make nylon insulators with a lot of stop and start leading to motor burn out. I appreciate you can use the v belt tensioner as a clutch but prefered staying safe.

The lathe can now be stopped and started as much as I want plus the biggest bonus is I don't need to muck about with belt changes and I can experiment with different speeds on the fly! Also the vfd motor on the lathe runs a lot smoother which imho produces a better finish.

Im glad to know that vfd can be done on a budget the speed 10 had a newton tesla unit fitted which was quite expensive.

Following Pauls post I did a bit of homework and I found that Proxxon have over-egged the power rating on the motor it is not 400w only 180w!!!

Before anyone checks I have my facts right I checked with Atas the motor manufacturer.

No wonder the motor gets hot and has a short duty cycle, it seems as other people have said that Proxxon are overpriced and under engineered!

That said compared to the Manix mini 140, which I think this was inspired by, it is a bit more beefed up in terms of parts. Which brings me round to my motivation to upgrade the motor.

I was thinking hyperthetically I could put 550w 3phase motor. The only problem I can think of is the 3 phase motor I found would be 6kg instead of the existing 4kg 1 phase. Would this be a problem either in extra weight or torsional stresses?

Hi Jon

Have you considered a .37kW motor, it may have enough power for a small mill and will be twice the original power unit, may be slightly lighter than the 550 W motor.
What speed motor are you seeking ? 1450/2800

Emgee

I fitted a 3-phase motor/invertor to a small (1MT spindle capacity) milling head last year - I used a 0.37kw motor having a "56" frame size and a "B14" flange mount, the shaft is 14mm dia.

0.18kw-and up are available in this frame size. About £50 new - check the "min" operating frequency/torque values - cheaper motors suffer more in this area, more expensive ones are better spec'ed at the lower end.

The motor is c. 100mm in diameter, 180 long, and has a 60mm spigot with four 6mm bolts on a 75 (or is it 76) mm PCD - if this helps as a starting point for further research. Specs may differ by maker - check!

I used two step pulleys to get useable ranges from about 350-2500 rpm from a two-pole motor, might have got same speed & more torque from a (safely) over-driven 4-pole, maybe someone can comment?

About £56 new mid-range motor & £50 cheapy (but very well-featured, nonetheless) vfd..

Now I really MUST go to work...

D

Can anyone explain frame rate on 3 phase motors? I am chewing through the technical jargon on motors and my understanding is getting better, but I still have large gaps in my knowledge.

One other consideration in selecting my replacement motor is working temperature. My workshop is in a conservatory so typically +30 degrees in summer is not unusual.

Would I need to choose a motor with integrated temperature sensor to warn or shut down if the coils get too hot? Or failing that rig up a thermister sensor?

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Hi Barrie

Part no for atas motor J22RX439, pm me if you want the technical data sheet I have it on my hd.

In answer to Emgees question the current motor outputs 2850rpm without reduction and 180-2500 with pullies, so I would at least like to match that perhaps go beyond for really small drills and cutters.

[This posting has been removed]

For fundamental physical reasons the generally accepted "satisfactory performance" range of ordinary induction motors driven by VFD is ± 1/3 rd of the name plate speed. Unsurprisingly torque, power output efficiency et al all deteriorate as a motor moves further away from the speed its designed to run at. If you go far enough away it hasn't got enough oomph and may very well run very hot due to inefficient running.

Exactly how far away is too far depends of motor and VFD design details. Good quality motor and high end vector drive VFD will give much better results than the bargain versions. Power loss at lower speeds is inevitable so for milling machine duties the hard limit is generally found when using large cutters which need to run at low speeds.

Given the choice I'd not use a two pole motor unless there is room to alter pulley sizes to give extra mechanical reduction. 6 pole motors are probably the best choice as the lower base speed means that torque and power holds up to lower speeds than with a 4 pole motor. High speeds are for small cutters which don't need so much power to drive them so power loss isn't so important.

Its often said that VFDs operate at constant power when running a motor above its rated speed. The reality is much more complicated, especially with vector drive units, and motor characteristics dictate an output power drop. Many modern motors have a "maximum VFD frequency" or equivalent on the data plate. This can be taken as the highest VFD input frequency for constant power operation. 70 to 90 Hz is a common value range. Above this frequency motor power falls off.

A two speed pulley drive, as suggested by DiogenesII, is a good idea. My old VFD driven mill had a range of 125 rpm to 1,400 on low speed and 250 to 2,800 rpm on high speed.This worked well with a wide overlap range so changing belt positions was rarely needed. That said I'd have traded a bit less overlap for lower bottom and slightly higher top speeds. Despite obvious power loss once out of the ± 1/3 rd nameplate range I always found there was enough power for my needs but the machine was strong enough that it could have been driven hard enough for power loss to be an issue. It had a 4 pole motor.

Clive