DIY CNC Mill - Playing around with the thought

[Stigoe]

I have 220V. I was thinking I could use multiple power supplies - so that each servo, and the spindle, can get their own. Connected to different ports around the house. That way I can distribute the load, and get around the need for all power through one port. I don't have a 3 phase circuit at home, and getting one in my neighborhood would be next to impossible - or at least exceed the the cost of the VMC by itself. I have electrician friends that I hope could help me find a way to make the multiple power-supply idea work.

Unless you have an old house with old incoming electrical wiring, you have 3-phase coming in to your house, but this is just split up for all the normal circuits.

5. I'm Norwegian, so English is not my mothers tongue. You say I need torque, and not RPM for steel - but 12K RPM is a good middle ground for aluminium and steel? How would I measure the torque in a spindle? By horsepower? Kw? Would eventually the spindle I found with 7.5 Kw be sufficient?

If that spindle will pull 7.5Kw, you will need more than a 32 amp circuit just to power the spindle and I can more or less guarantee that you don't have that in your house. Normally you have one 20 amp or 25 amp socket in the house, which is for the oven in the kitchen.

Whereabouts in Norway are you located?

[DuxEtCapital]

Yes power will be a problem, especially on the spindle. Faced the same issue on current build. Most dedicated spindle motors are 3 phase.
I am testing one now that is single phase 2.2kW 8000rpm.
That being said I have 15amp circuit supplying spindle & 10 amp circuit supplying controls & servo's. Both 240v single phase.
What sort of travel distances are you looking for?
Regards,
MichaelAttachment 403012

I am aiming for a work area of 1000x800x800mm work area, so with the mounts for the linear guides I guess I'm looking at about 1400x1000x1000mm of travel distance.

Have you had any success with cutting steel with the 2.2kW spindle? Does this spindle have to spin at 8000rpm, or can you regulate it so it moves slower?

I'm sorry for my late replies. I'm working night shifts this week.

[DuxEtCapital]

With access to equipment you have your project is certainly possible.
I used multiple tube (10mm wall) boxed & welded together. 25mm flat bar for rail mounts. Head was multiple laser cut 10mm plate. Whole lot internally braced & welded as well, has been post weld heat treated & will be filled with epoxy when done.
Using 30mm linear rail with 25mm C3 double nut ballscrew. Some of my biggest expense was machining that had to be sent out as my knee mill too small.
Regards,
Michael

Very, very nice build! I'm in luck that I have the machinery that I have available - might be able to save quite a lot of bucks that way.

I was looking through HIWINs products yesterday, and I came across some linear guides that I haven't considered before.

The plan is to mount the X-axis onto the back wall of the machine with two QRW45CC linear guides, and one 32mm double-nut ballscrew. Then mount the Z-axis onto the slider plate of the X-axis, with the Y-axis mounted to the Z-axis (if that made any sense). I could throw up a quick sketch in paint or something when I get back home tonight, as I don't have my CAD-computer at the moment.

According to HIWIN, the QR series offers super-high rigidity, and quiet operation - combined with long running life. Sounds like exactly what I need - or do you think this is a bit overkill?

Hanermo says that I would be just fine with 400w servos, what is your thought on this? I'm starting to realize that I have to compromise with the some of the electrical components to be able to run this mill on 220V single phase. I found some 750W servos for quite a bit cheaper than the ones I posted in the OP.

https://motioncontrolsystems.hiwin.c...eries-assembly

https://www.ebay.com/itm/2-4NM-750W-...4AAOSwjh5bFjdD

[jgwentworth96]

Very, very nice build! I'm in luck that I have the machinery that I have available - might be able to save quite a lot of bucks that way.

I was looking through HIWINs products yesterday, and I came across some linear guides that I haven't considered before.

The plan is to mount the X-axis onto the back wall of the machine with two QRW45CC linear guides, and one 32mm double-nut ballscrew. Then mount the Z-axis onto the slider plate of the X-axis, with the Y-axis mounted to the Z-axis (if that made any sense). I could throw up a quick sketch in paint or something when I get back home tonight, as I don't have my CAD-computer at the moment.

According to HIWIN, the QR series offers super-high rigidity, and quiet operation - combined with long running life. Sounds like exactly what I need - or do you think this is a bit overkill?

Hanermo says that I would be just fine with 400w servos, what is your thought on this? I'm starting to realize that I have to compromise with the some of the electrical components to be able to run this mill on 220V single phase. I found some 750W servos for quite a bit cheaper than the ones I posted in the OP.

https://motioncontrolsystems.hiwin.c...eries-assembly

https://www.ebay.com/itm/2-4NM-750W-...4AAOSwjh5bFjdD

Here's a link to a store that bought all the remaining stock of HiWin America and sells their stuff at great prices.

http://www.automation-overstock.com

[DuxEtCapital]

A full isolation enclosure with external venting would make it a lot better, also take a lot more room (just how big is your desk!?? ). Not sure I'd bother with a chip conveyor/screw, you have enough on your plate as it is. You'll end up using the blow gun, though, with the cover off, and it's going to end up going everywhere. Still, you're already thinking of all this stuff and are one step ahead of most attempting it, you may be able to make it work.

Hahaha, I think I am confusing you with my writing here. I am going to build it into my 'computer corner', besides my desk - not upon it :P

The total space I have I about 2000x1400x2700mm - so as long as I keep within these dimension I should be fine!

Thank you for the support, friend! I'm going to do my best pulling this of, but the build probably won't commence until a year at least. I have a lot of research and design to do before I can even order materials.

[DuxEtCapital]

Unless you have an old house with old incoming electrical wiring, you have 3-phase coming in to your house, but this is just split up for all the normal circuits.


If that spindle will pull 7.5Kw, you will need more than a 32 amp circuit just to power the spindle and I can more or less guarantee that you don't have that in your house. Normally you have one 20 amp or 25 amp socket in the house, which is for the oven in the kitchen.

Whereabouts in Norway are you located?

I live in Askim, but I'm going to relocate in a year or so. I'll probably stay within Askim though, as it is here I work.

My problem on the 3-phase question is that I'm not planning on entering the house market any time soon, so I'll probably just keep renting an apartment. Thereby using thousands of dollars to install something that most likely never will be used by other than me would be a waste of money. I have to find a way to stick with 220V single phase - eventually by compromising with the spindle and servos to an acceptable level.

[Stigoe]

I live in Askim, but I'm going to relocate in a year or so. I'll probably stay within Askim though, as it is here I work.

Not far from me then. I live in Lørenskog. :-)

[hanermo]

The common VMCs usually used == 1 kW direct-drive servos for a long time.
Latest few years, 2-3 kW.

And they drove a very heavy thick metal milling table.
And they were very interested in max acceleration and max rapids - for commercial marketing reasons mostly.

The 40 hp / 25 kW Haas machines with == 2kw axis servos iirc, tended to use 2-3-4 kW of power for cutting steel, mostly.
Like our demo cuts in our demo room with 7 machines.
The acceleration on the spindle was 100%, for 1-2 secs, but then the power needed dropped way down.

I have 750W ac servos, 10.000 counts, on the lathe but use only 20-30% of their peak power and acceleration.
This cuts down on screw and slide wear, a lot.
My next-gen lathe saddle will now have 2 toolchangers, front 4 -way (double tooling) and back 7-way servo turret, 70 kg mass.
Total == 150 kg mass, all-in.
That mass could be accelerated to 3000 rpm peak servo speed in about 0.05 secs at 750W / 10 Nm == 700 kgf thrust. Or == 4.x G acceleration.

The VMC mill table == 200 kg mass.
With 200-300 kg max load on table the 400W servo will still be more than 100% of extra overhead in terms of power and torque and push.

I previously used a small nema 32 stepper, 48V, on the vmc.
At 1:3, HTD belts, 5/15 mm.
It worked fine, at max == 800 rpm speed == 260 rpm at screw.
(With poor roton ballscrew of 5/8" / 0.2" rise).

The practical torque from the stepper, 3Nm nominal, is == 50%.
So about 1.5 Nm, upto 800 rpm, some spare for load on the table.

The 400W servo, 4Nm peak iirc, is about 2.5 faster and 3-4x more accurate.
And I don´t need the speed or acceleration, I need the accuracy and rigidity.

I try to explain my reasons and experiences and spice with some engineering data for credibility.

- - - Updated - - -

PS.
Get the heavy preload if you can !

[mick41zxr]

Mate at 1400x1000x1000 rails will be a substantial machine.
For instance my machine will be 500x300x350 travel. with x rails being 950, y 600, z 600.
Frame alone before epoxy is approx 600kg. Completed with stand, motors, spindle & enclosure approx 1T.
Machine can be broken down into major components so it can be moved by two people without specialized equipment.
Enclosure size will be approx 1500x1200x2100.
A Haas Mini Mill by comparison stands at over 1.5T
With regards to spindle I have only bench tested at this stage. It is an Asynchronous Servo with 2500 line encoder, it can be controlled down to any rpm in speed, torque & pwm mode.
Regards,
Michael

[kawazuki]

No one seems to have mentioned this, so I will........ accuracy = rigidity = mass = weight! I hope you are planning this on the lowest floor of your house! You intimated a move to an apartment later? I would imagine your neighbours wouldn't take kindly to, a) the noise, b) the potential smell, and c) the possibility of them finding your machine in their Living Room if the floor collapsed LOL!
Your work envelope of 100 x 80 x 80cm would surely require 'table movements of min, 200 x 160 x 100cm + extra to clearance rapids and tool changing? Then add an enclosure? I think your looking at using all the space available (and some) with weight of........loads kg ! A quick comparison of a commercial Haas or Fadal VMC with your quoted work envelope will confirm likely o/all space requirements..... For instance, this one only hits one of your targets - Haas VF-3 | Haas Automation, Inc. | CNC Machine Tools - check out the weight - WOW!

[JoanTheSpark]

I have 220V. I was thinking I could use multiple power supplies - so that each servo, and the spindle, can get their own. Connected to different ports around the house. That way I can distribute the load, and get around the need for all power through one port. I don't have a 3 phase circuit at home, and getting one in my neighborhood would be next to impossible - or at least exceed the the cost of the VMC by itself. I have electrician friends that I hope could help me find a way to make the multiple power-supply idea work.

The point is not the number of sockets in your house or flat or apartment to distribute the load.
What is important is the connection to the grid.
How many phases?
What amperage rating?
Look at the fuses on your main board where the grid connection comes in, next to where the electrical meter is that's responsible for you.
The big ceramic fuses there.
What is their rating?
How many of them are there?
That's what you got.

I'm in rural Australia and in my little street out in nowhere we got some '2 phase' (180deg), with 32A per phase at 230Vac.
Back in Germany (single house in city, 10 years ago) we had 3 phase 32A per phase at 230Vac.
I think the biggest one can get for residential in 230Vac areas is 64A per phase.

So with everything else OFF on one phase I can run 32A x 230Vac ~ 7kW, total. Anything above that and I blow the fuses on my grid connection.
And honestly, if I'd have a need for machines bigger than this I'd better get some space in an industrial park and make money with it. ;-)

Hahaha, I think I am confusing you with my writing here. I am going to build it into my 'computer corner', besides my desk - not upon it :P
The total space I have I about 2000x1400x2700mm - so as long as I keep within these dimension I should be fine!

Have you checked the load bearing of the floor?
Anything that isn't on ground level in residential buildings usually tops out at 300kg per square meters..

Also, are you sure you need those large dimensions for steel capability?
Building something smaller that can do steel and something larger that can do aluminium should be easier.

Also, from what I have noticed ATC spindles from China that are affordable and in sizes that hobbyists use (BT30.. maybe even BT40) are usually for aluminium (high rpm, low Nm).
To get the torque for steel at affordable prices and motor sizes one has to combine a servo motor with a milling head via toothed gear belts.
This CNC build is using this approach: https://www.cnczone.com/forums/uncat...aluminium.html
ATC then is a matter of modifying or adapting the rear of the milling head.

[dharmic]

The point is not the number of ports in your house to distribute the load.
What is important is the connection of your house to the grid.
How many phases?
What amperage rating?
Look at the fuses on your main board where the grid connection comes in, next to where the electrical meter is.
The big ceramic fuses there.
What is their rating?
How many of them are there?
That's what you got.

I'm in rural Australia and in my little street out in nowhere we got some '2 phase' (180deg), with 32A per phase at 230Vac.
Back in Germany (single house in city, 10 years ago) we had 3 phase 32A per phase at 230Vac.

So with everything else OFF on one phase I can run 32A x 230Vac ~ 7kW, total. Anything above that and I blow the fuses on my grid connection.

The only way out of this for me?
Solar on the roof and a big battery in the shed, but that's years out and island systems that are able to provide 10kW continuous are no cheap either ;-)

Strewth! Strike me pink, but I always thought two phase in Oz was a case of “there are three legs, pick any two” ie 120° apart.

Where in Oz?

[JoanTheSpark]

North Queensland, Atherton Tablelands, 100km SW of Cairns. A couple houses in a very odd development from like 40-50 years ago that doesn't look like it went by the book (read: farmer cut off some grazing area, put a road in and made some bucks). I think 6 or so houses fed off of a small transformer that is fed 3 phase 19kV and has a total rating of 25kW if I remember correctly. A couple meters (same street oddly enough) there is a real 3 phase transformer for more houses.

So yeah, we get neutral and 2 phases that are 180 deg apart.

[dharmic]

Atherton and surrounds would be exactly the kind of place to have some bizarre power setup of their own. We came visiting from WA a year ago, loved it up there. The “spy museum” in Herbeton(?) was the highlight - guy running it was a vaudeville show on his own, nuttier than Granny’s fruit cake. From there to coffee at the lolly shop, and the lady there made us feel so at home. Crazy, quirky region full of different people all generally getting along and getting on with it. All seemed like such a chilled place to live if you could find a way to make it work. I loved the place.

I’ll admit it, I’m a little jealous of anyone who’s found a way to live there!

[skrubol]

North Queensland, Atherton Tablelands, 100km SW of Cairns. A couple houses in a very odd development from like 40-50 years ago that doesn't look like it went by the book (read: farmer cut off some grazing area, put a road in and made some bucks). I think 6 or so houses fed off of a small transformer that is fed 3 phase 19kV and has a total rating of 25kW if I remember correctly. A couple meters (same street oddly enough) there is a real 3 phase transformer for more houses.

So yeah, we get neutral and 2 phases that are 180 deg apart.

So you've got 480v line to line? Never heard of that in single phase. (480V 3 phase is common in the US)

In the US, the standard is 120/240V split phase (is what it's typically called. 180 deg.) Service current ratings are quite a bit higher though. My house is fairly typical with a recent service install and it's 200A (48kVA.)

[JoanTheSpark]

So you've got 480v line to line? Never heard of that in single phase. (480V 3 phase is common in the US)

In the US, the standard is 120/240V split phase (is what it's typically called. 180 deg.) Service current ratings are quite a bit higher though. My house is fairly typical with a recent service install and it's 200A (48kVA.)

Electricity (Voltage Limits) Amendment Regulation 2017 - Queensland

The standard voltage for the supply, before 27
October 2018, of electricity at low voltage from a
single phase system is ..
(a) between a phase conductor and a neutral
conductor ... 240V;
and
(b) between the phase conductors ... 480V.