[tef9]

Hi,

Think I have bought this up before however, I am keen to get more from my spindle. Having looked at the Tormach PC770 and what it can deliver I wondered if I could achive similar.

I am thinking about using somthing like this:

Zapp Automation Ltd - Stepper motors & Stepper Motor Drivers - Servo motors and Servo Motor Drivers - Ballscrews & linear motion products. : 1.05KW (5Nm) AC Servo system [CD430+SMH110D-0105-20AAK] - £785.00

I prefer the servo over VFD and three phase motor as it seems a much smaller package...am I barking up the wrong tree with this? Is it suitable. Is there an alternative? Would this be a waste of money?

Lastly I would also like to know what style bearings I would need to upgrade the spindle. I have asked around where I work and get varying opinion. For these mills do we really need SKF ceramic angular contact bearings? or is this over kill? If so what is the alternative?

Any help would be appriciated.

If it helps I normally cut Brass and Ali...however I will have to move to stainless steel soon.

Thanks,

Andy

[LongRat]

I think if you want to move to steel the requirement for an upgrade will actually reduce. You won't need the speed and the power of the standard set-up is actually pretty good. I found that the performance of the mill is really being limited by the spindle when cutting aluminium, it just isn't fast enough. Taking the RPM up to 4000 let me increase my feeds by up to 5 times. I think the RPM rather than the power is where the mill is lacking, and with that in mind, I'm not sure where the AC servo delivers. It isn't going to allow you to go faster than a VFD and AC motor setup and it isn't all that powerful either at 1kW. If you want to look at synchronised moves like rigid tapping then that's a good reason to go for it - if it has sufficient torque at low RPM.
I think you would need to be pretty sure you wanted a servo on there to justify the cost, at well over twice the price of an AC motor and VFD.

[digits]

I've just splurged on a 6Nm/1.6kW servo and drive from Zapp for my BF30 clone. It was considerably cheaper than that package - the drive was £300 which is the same as a vector drive, and the servo was £260 which is £100 (all ex VAT) more than a 1.5kW induction motor - I also bought the cable set to connect them all up from Zapp.

What will it buy me? Well, hopefully a few more rpm - like LongRat I'm into ally mostly, but the reason I went for a servo was that the motor is half the weight/volume of a similar 1.5kW induction motor.

It is going to take me a couple of weeks to get this setup up and running - I wired it up last weekend but I need to sort out a belt drive setup to get it on the mill.

[SCzEngrgGroup]

Are those motors really suitable for use in a spindle? I notice they're not ventilated at all. If you run a long time at high speed/load, what keeps them from over-heating?

Regards,
Ray L.

[Hans_G]

heat is a consideration for sure. I use a Nema 34 BLDC servo for my spindle motor and it gets quite hot. I thermal-epoxied some big (relative to the motor size) heat sinks to the 4 sides, and it has helped quite a bit (motor case temps after 1hr at rated speed dropped from 145F to 110F).

[LongRat]

Yeah, there's no getting away from the heating if they are half the size of an AC motor. After several hours of full-speed running my motor is barely warm. I suspect my average power draw is probably less than 10% of the motor's capability though as I mostly use small cutters <10mm.
Also I decided not to go for a vector drive, just a standard cheap type. I think my motor was £120 inc VAT... so all-in a LOT cheaper than a servo. If you often run at much lower speeds than the max and don't want to shift belt ratios, then vector wins. Personally I fancied saving the extra coin this time. I would be interested to hear how both servo systems work out on the BF30 and how the performance compares.

[digits]

I guess we'll have to see how hot it gets, but as I understand it, the heating should be less of a problem in an AC servo because unlike a brushed-DC or AC-induction motor, all of the windings are on the outside of the device, and therefore you don't need to actively cool the rotor.

Physically the motor I have is about the same volume as the stock DC-motor but it claims to be about 50% more powerful. I guess I'll find out soon enough!

[wizard]

AC induction motors, AC servos and steppers all have their windings located in the stator. This means that heat quickly travels to the outside of the motor, that leads to motors that can be extremely hot to the touch. They may be hot but also operating within operating parameters.

Over heating is possible though and such motors often have constant speed fans installed for force air cooling. Even if the motor operates within spec active cooling can help extend the motors life.

I guess we'll have to see how hot it gets, but as I understand it, the heating should be less of a problem in an AC servo because unlike a brushed-DC or AC-induction motor, all of the windings are on the outside of the device, and therefore you don't need to actively cool the rotor.

Physically the motor I have is about the same volume as the stock DC-motor but it claims to be about 50% more powerful. I guess I'll find out soon enough!

Remember that the rating comes at a specific speed value. You still have real torque limits and they impact how well you will be able to use the motor over its range of speeds. 50% is pretty good increase in power and should help but you but the more power the greater your useful speed range.

[hydropro]

I have a Prolight 1000 CNC Mill that originally had a Baldor 7500rpm 1hp 90vdc motor and was geared down to 4700rpm max at the spindle. The motor would get very warm after an hour or so of use. I replaced the motor with a NOS Pacific Scientific .85hp AC Servo Motor and Drive system that I purchased on ebay for $250.00 I installed the motor with a 1to1 pully ratio and get 4700rpm at the spindle. The results were more torque at lower speeds and the motor only gets warm after several hours of use at high speed, its also alot quieter. I have no regrets with making the switch. Hope this helps.

Regards, Jose

[tef9]

Thanks for the replys, Sorry its taken me a while to respond have had "Man Flu".

I think if Digits is already heading down this road I will see how well it works out for him. I have seen that alot of Pro tool manufactures like Haas use belt driven spindles with AC servos. How do they cope with hard metal like SS and the like? Is it due to the power of the spindle motor (i.e 7.5Kw) Or do they do somthing else?

I do like Long Rats set up Its just the motor looks huge on the machine!

Long Rat - does it add any tilt or affect the head tramming?

Cheers,

Andy

[digits]

Sorry guys - I've been a bit busy lately and I haven't really got much further yet. I've had the servo all wired up on my desk for the last couple of weeks, and I've finally just read enough of the manual to get it to move under jog control - so at least I know it works!

I need to get some CAD done for a motor mount during the week and I'll have a go at cutting it out at the weekend as long as the stock motor wants to play ball.

I still need to get some electrical bits and bobs though - I need another enclosure to put the drive in to keep it safe from chips and coolant, and I think I really should wire an EMC filter in there too.

[LongRat]

I do like Long Rats set up Its just the motor looks huge on the machine!

Long Rat - does it add any tilt or affect the head tramming?

Cheers,

Andy

I don't think it looks out of place really. Proportionally it isn't a lot different from the RF45 in terms of head size to motor size. The motor itself is still only a small fraction of the weight of the head casting itself, I haven't noticed any problems with tilt.

[digits]

Thanks for the replys, Sorry its taken me a while to respond have had "Man Flu".

I think if Digits is already heading down this road I will see how well it works out for him. I have seen that alot of Pro tool manufactures like Haas use belt driven spindles with AC servos. How do they cope with hard metal like SS and the like? Is it due to the power of the spindle motor (i.e 7.5Kw) Or do they do somthing else?

I do like Long Rats set up Its just the motor looks huge on the machine!

Long Rat - does it add any tilt or affect the head tramming?

Cheers,

Andy

Have you put your steel cutting speeds and feeds though something like G-wizard? If you discover you want loads of torque at low rpm, you will probably still need to gear the motor down to the spindle - my plan was to gear up slightly to give me 3600 rpm from a 3,000 motor, but I will have less torque at low rpm.

I guess the industrial boys do just use massive motors if they have direct or single speed belt-drives. The torque is related to the current, and the speed to the voltage, so on a single phase UK mains setup, you are going to be limited to by the max current you can supply, even if the motor is up to it. I think the drive I have is good for 29A peak, but I'm only fusing it to 10A as the motor's only good for 6A sustained and I want this to plug into a normal mains socket.

[tef9]

Thanks for the info digits, look foward to seeing yours in action. I see its pointless me buying a 15Kw spindle! Without three phase mains that is. Oh well.

Long Rat, is your set up similar to this:

SINGLE TO 3-PHASE INVERTER & MOTOR FOR HARRISON LATHE | eBay

I will investigate the feeds and speeds. At least then I have an idea as to what I need. But stainless is a requirement though not the only metal I use. Aluminum, Brass and bronze are all there. Even wood occasionally when dad is upto his Diy antics!

Andy

[Mad Welder]

…….. - my plan was to gear up slightly to give me 3600 rpm from a 3,000 motor, but I will have less torque at low rpm.

I guess the industrial boys do just use massive motors if they have direct or single speed belt-drives. The torque is related to the current, and the speed to the voltage,………….

Hi there, i got this link The best way to buy industrial controls--low prices, fast shipping and superior service.from one of the other members and check out their AC Drives and AC motors...this isn't my field but I'm looking to beef up my 850W DC motor and I was looking at different options to and I'm kinda leaning towards the AC DURApulse drive from that company I'm waiting for shipping quotes at the moment.....one point that might be of interest to ye is in an email back from the company they suggested one configuration and here's the quote from the chap "Constant torque range: 100 to 1750 RPM" and my understanding is that manufacturers apparently can manipulate the current now a days which kinda throws the normal formula of Volts Vs Torque relationship out the window.

Hope I haven't confused matters but as your still deciding I thought it may be of interest to ye....

[digits]

Hi there, i got this link The best way to buy industrial controls--low prices, fast shipping and superior service.from one of the other members and check out their AC Drives and AC motors...this isn't my field but I'm looking to beef up my 850W DC motor and I was looking at different options to and I'm kinda leaning towards the AC DURApulse drive from that company I'm waiting for shipping quotes at the moment.....one point that might be of interest to ye is in an email back from the company they suggested one configuration and here's the quote from the chap "Constant torque range: 100 to 1750 RPM" and my understanding is that manufacturers apparently can manipulate the current now a days which kinda throws the normal formula of Volts Vs Torque relationship out the window.

Hope I haven't confused matters but as your still deciding I thought it may be of interest to ye....

Is constant torque what you really want though? Say you have a 1kW motor - mechanical power is in W is (revs/s * 2 * pi * torque) so with a 100-1750 rpm range, at max rpm it will have 1000W / (1750rpm/60 * 2 * pi) = 5Nm, but it will also have 5Nm at 100 rpm, where it will only have 5 * (100/60 * 2 * pi) = 57W of power. 57W isn't going to remove metal rapidly with a big drill...

I would have thought you would want constant power in a machine tool - which is what you get with a gear box - you run the motor in the optimum power rev-range, and the gears turn that down to a scary amount of torque at low rpm.

Look at Tormach - they have a fancy vector-drive AC inverter setup, but they still use a 2-speed belt drive to get the most out of the motor. I suspect my single speed belt drive will be less capable at low speeds than the stock motor and gear box, but I'm hoping I won't care - I would rather mill out 20mm+ holes in steel than try and drill them out as the machine isn't that rigid despite weighing nearly 300kg.

[Mad Welder]

thanks for the explaination:cheers: and nope I'm not sure if constant torque is what I’m looking for and the largest drill diameter I used in my little BF20 is 16mm and anything over that diameter I would normally mill a circular pocket...the formula's I leave to you guy's who understand that as i don't but I had intended to include a two pulley belt driven spindle in my build too..I thought that the link had a large range of Drives and Motors too

[Mad Welder]

.............you run the motor in the optimum power rev-range, and the gears turn that down to a scary amount of torque at low rpm......

aaaaahh now I get it (the penny droped:idea....... and there's me thinking that everyone was using pulley driven spindles to increase RPM from the motor's RPM output.......

isn't it great when moments of understanding come you don't feel as thick anymore:wee:


:cheers::cheers:

[LongRat]

Long Rat, is your set up similar to this:

SINGLE TO 3-PHASE INVERTER & MOTOR FOR HARRISON LATHE | eBay


Andy

Andy - my set up is not the same but similar. Motor looks to be the same size and power, but mine is a higher RPM (2 pole I think 2700 RPM... not sure) and is end-mounted rather than foot-mounted. The inverter looks much the same, mine's a TECO brand one. I got the stuff from Drives Direct. With my 2-speed belt drive, I have sufficient torque at all speeds for this machine. Like Digits says, don't try running a 40mm drill in steel on a BF30 as the rigidity isn't there even if the spindle drive can handle it.

[Mad Welder]

Andy - my set up is not the same but similar.....

oops I hope I haven't confused or side tracked your thread...