Slant bed CNC lathe from scratch

[Guldberg]

More progress pictures

Bracket for the console and backcover


I suck at welding...


The high voltage stuff that is going in the left side cabinet of the stand. Consist of a huge transformer for the stepper power supply and a VFD for the spindlemotor. To be added is a stack of solid state relays and a "power distributor", im using 3 phases 380v as input which splits in to 3x1 phases, one for the VFD, one for the stepper psu and one for BOB, computer, pump etc.

[handlewanker]

By the way Guldberg, I'd be carefull about using the phases as seperate circuit supplies, in case you get a phase imbalance and a ripple on the line.

The last firm I worked for had this problem to such a degree that our section leader used to go to the power cable inlet supply board around midday, each day, and hand feel the temperature of the three input phase cables to see which one was taking the most current.

When one got too hot to handle, I kid thee not, we used to shift machinery from one phase to another to even out the supply.

Eventually we had a larger transformer/substation attached to the pole outside the 'shop which supplied the needs.
Ian.

[Guldberg]

Phase imbalance and line ripple, words i dont understand:-D But i like the idea of just touching the power cable to tell if its hot, that was my initial plan, either that or the fuses pop i guess. Worst case its going to run a couple of hours, no real production runs

[Guldberg]

Let there be pictures

Fuses


Relays and 380v -> 220v


Stepper drivers and BOB


Stepper drivers heatsink

[Guldberg]

Hurray. The console have now been PTFE coated in a nice black finish. It looks beautiful:-) Unfortunally the plate where the buttons are placed was coated on the wrong side, so they have to do it over. The plate in the picture is just for mock up.
Man, is touchscreen just the coolest thing or what? Ill try and connect it to my router tomorrow and take some video.

[Guldberg]

Got a Homann ModIO today. Went straight to the basement and installed it. Now i have all the I/O i need. I just need to figure out why output 1-4 (pin 0-3) is flashing when turned on. Anyone? Also bought the LCD display which i plan to plant inside the enclosure so its visible when dialing in parts etc.

Edit: The flashing was a feature enabled as standard, just had to change a registry setting

[chich2]

Great Thread Guldberg! Nice and neat!!!!

Keep up the good work.

Chich

[Guldberg]

Change of plans. After carefull thinking ive made a radical design change. Instead of the whole machine being angled ive desided just to angle the carriage. Now machining, welding etc. will be a lot easier. Also i can make a one-piece waycover that slides in behind the headstock. Im also leaning against filling it with polymere concrete or what ever they call it:-)

The disadvantage is the increase distance from the cutting force to the rails, but the distance isnt that great when thinking of that when cutting normal diameter work (20-40mm) the turret is near the bottom and close to the rails

A quick drawing, what say you?

[Al_The_Man]

By rights, you should not daisy chain either the DC + or -, it looks like the - is.
Also it is not always a good idea to fuse the DC to the amplifiers?.
Al.

[Guldberg]

Hmm. Should i fuse it on other side of the caps? I guess you say this because the drivers will be unable to "dump" the energy in case the fuse pops?

What are the disadvantage of daisychaining the commen ground or +? They are going to be controlled from the ModIO, so the + will be the commen (have to change the wires, right now the ground is the common)

[Al_The_Man]

Should i fuse it on other side of the caps? I guess you say this because the drivers will be unable to "dump" the energy in case the fuse pops?

That is usually the reason for fusing before the capacitors.

What are the disadvantage of daisychaining the commen ground or +? They are going to be controlled from the ModIO, so the + will be the commen (have to change the wires, right now the ground is the common)

Normally it is recommended to take each drive power feed, including both the +ve & -ve by independent conductor from the caps to each drive, this allows a very low impedance source to each drive and any one drive current is not being shared or affected by another.
If you do not ground the AC input to the P.S., you can if you wish, ground the P.S. DC -ve line.
Drive manufactures usually suggest your choice of floating DC or one side taken to a common ground point.
If you are setting up this way, then you could ground the -ve.
If you are setting up a system with total isolation, then you may want to operate with a floating DC supply.
With a grounded system, the ground should never be used as a normal conductor.
Al.

[chich2]

Guldberg,
I like your new design with the bed offset from the headstock. That is a great idea having the way cover simply protrude past the head stock. Good thinking. Yea sure it may come at the cost of a bit of twisting but i'm sure you can beef up the bed if it is that much of a concern. Would you also put an offset tail stock on that design?

Chich

[Guldberg]

That is usually the reason for fusing before the capacitors.



Normally it is recommended to take each drive power feed, including both the +ve & -ve by independent conductor from the caps to each drive, this allows a very low impedance source to each drive and any one drive current is not being shared or affected by another.
If you do not ground the AC input to the P.S., you can if you wish, ground the P.S. DC -ve line.
Drive manufactures usually suggest your choice of floating DC or one side taken to a common ground point.
If you are setting up this way, then you could ground the -ve.
If you are setting up a system with total isolation, then you may want to operate with a floating DC supply.
With a grounded system, the ground should never be used as a normal conductor.
Al.

Im a bit confused here. The stepper drivers are not daisychain, just the solid state relay. But i guess what you mean is that i should run independent wires both + and - from the cap to each driver. I think ill do that, but leave the fuses in, just because they are allready there :-)

As for the relays ill run independent wires from the screw terminal to the relays, but a single wire from the ModIO to the screw terminal.

I dont plan for a tailstock at the moment, but the possibility is there:-)

[handlewanker]

Hi, that's a major design rethink.

I like the offset headstock arrangement.

I get the feeling that you're carrying a bit of weight in the crosslide with the turret and tooling.
Do you reckon you'll need a counterbalance for the slide?

Looking at this new design I can visualise a 20 + rotary magazine behind the headstock with direct injection, (no robot arm), to the tool post when the slide moves upwards and towards the headstock.

I like the idea of multi tooling off the lathe, like when you have a QCTP with multiple tool holders on a centre lathe as opposed to just a four way tool post.

Your magazine could be as big as you want without a weight restriction affecting the crosslide movement, and the rotational mechanism is not too critical as far as having to bear the cutting forces of a turret type on the crosslide.

So this would also mean that the crosslide could be "slimmed" down as it would only need to carry one tool holder.

There's far more scope with a 20 tool magazine.
Ian.

[gotis]

Uhm!

Build it like it is in you rendering and just slant the base.

I was thinking of mounting mine vertically, just for kicks (and smaller footprint) would fit perfectly in my shops corner.

[Guldberg]

Im also considering this. The advantage of this design with the crosslide angel is that is "sticks" out in front of the headstock, making it possible to fit a way cover that slides behind the headstock.



Weight doesnt consern me, actually the extra weight could be an advantage as a mass dampning feature:-)

[hybidder]

Very interesting thread.

I have a Hardinge dovetail bed lathe (missing the crossfeed/ saddle) that might make a good base for a similar setup. I'll be following this thread closely.

Great work so far, best of luck.

[svenakela]

There's a guy in Germany that is close to your design with his home built lathe.
http://www.cnc-projects.de/CNC-Drehbank.html

I like the first angle-everything better though.
Great build log by the way, I think it'll be a great machine!

[Guldberg]

I looked at the german site many times, his work is impressing, especially his router. His lathe design is build on linear rods and bearings which flexes under the cutting force. I think that he writes somewhere that he is only able to turn brass etc.
I like the original design better as well, but it had to many disadvantages when it came to actually building it. You have to be aware of your capabilities:-D

[the4thseal]

i wish i could read his page