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CNC router specs
« on: February 15, 2019, 04:10:48 PM »
hello my friends,
i'm new here. excuse me if the topic is not in the right place.
i wanna make CNC router to start my 3D modeling business it will be 5 axis and more than one spindle, so which component you suggest to use like motor, spindle, software.
i planing to use 2X nema 34 for X, Y, Z axis, and nema 23 for 4th and 5th axis. but don't know about the spindle specs.
please if any one can help in this, and mach suitable version for 5 axis work.
« Last Edit: February 15, 2019, 04:32:15 PM by bryannab »
Re: CNC router specs
« Reply #1 on: February 15, 2019, 04:59:30 PM »
Hi,
you don't say what materials you want to cut and at what speeds.

The size an power of the spindle determine the weight and  the cutting forces the machine will be subjected to.
Deciding beforehand that you are going to use this stepper or that stepper for an axis is back to front.
Spindle <determines> Forces <determines> Weight/Rigidity <determines> Axis Components <determines>Steppers/Servos.

Craig
My wife left with my best friend...
     and I miss him!
Re: CNC router specs
« Reply #2 on: February 15, 2019, 06:22:50 PM »
Hi,
there are two areas where hobbyists/newcomers woefully underestimate when talking CNC.

One is the spindle. Most of us go for cheap spindles. Cheap spindles are underpowered, have poor bearings leading
to excessive runout, have low torque restricting the size of tools that can be used and materials that can be cut.

In particular many of the highspeed (24000) rpm spindles (from China and elsewhere) and VFDs are actually quite good
for soft materials and small tools but are hopeless for steel. If you want to cut steel, stainless steel, titanium or any
of the super alloys you'll need a high torque spindle. Your cheap Chinese 24000 rpm spindle just won't do it.

The other area that is underestimated is rigidity. Even if you have an adequate spindle your machine must hold the
spindle rigidly in place to cut the material. If the machine deflects even slightly then the accuracy of the part is shot,
and you'll likely get a vibration which further degrades accuracy and destroys surface finish.

I have made both mistakes. I bought a German made 24000 rpm 750W spindle. It works really well for engraving
(PCBs in particular) and does a good job with smallish (6mm and smaller) tools in brass and aluminum. When I try to
cut steel its not so good. I have cut mild steel with a 3mm endmill at 9000 rpm. I can't go much slower without the spindle
motor from overheating. Really 9000 rpm is a bit fast, without flood cooling the tool burns up. The real problem is though
that the spindle doesn't have enough torque and except with the lightest of cuts stalls the tool resulting in the tool being
snapped.

I really wanted to be able to cut steel so I ended up making a spindle to do it. Its powered by a second hand 1.8kW, 3500rpm,
6.2 Nm continuous (18Nm peak) AC Allen Bradley servo. Its direct coupled to a Rego-Fix (Swiss made) ER25 tool holder in NSK
matched angular contact bearings. Cost me about $2000 to make. It works really well.

That showed up the second problem. I made my mill out of cast iron slabs, approx. 220mm x 60mm x500mm. It has
15mm rectangular 4-point linear guides, C5 ground ballscrews and five phase steppers through low lash (<2 arc min)
planetary gearboxes. The column is made out of solid 80mm x80mm mild steel, note that's SOLID steel, not box
section, and yet it still flexes when cutting steel with my new spindle.

It works well but I have to limit the cuts to maintain accuracy and surface finish. I thought when I was building it that it would
be really rigid, and it is in fact, its just that I didn't appreciate HOW RIGID a machine has to be. I know more now!

The saying that '....only as good as the weakest link' certainly applies in CNC machines, and spindles and machine rigidity
tend to be the weakest links, both of which are expensive to fix, if it can be fixed without scrapping the machine.

Craig
My wife left with my best friend...
     and I miss him!
Re: CNC router specs
« Reply #3 on: February 18, 2019, 09:40:28 PM »
First, very sorry to be late.
Second, i want woodworking and aluminum so. and it will work heavy.
3D modeling will need tall tool, right? what about the spindle type and model ?
it will be about 1.5 X 3.0 m
rotary head. it needs also a stepper one.
i will use aluminum extrusion or aluminum plate with 15 mm thickness ,about 20 mm chrome shaft for holding. ball screw for 1.5 m side.
I think this information explained to you what I want to do, so you can advice me correctly,,,
and what about the electrical components for 5 axis ?
by the way i want to use Siemens NX or Catia v5 which i familiar with. what is your opinion!
thank you for your reply again.
« Last Edit: February 18, 2019, 09:47:33 PM by EnG_OmAr »
Re: CNC router specs
« Reply #4 on: February 19, 2019, 12:15:51 AM »
Hi,

Quote
Second, i want woodworking and aluminum so. and it will work heavy.
3D modeling will need tall tool, right? what about the spindle type and model ?

For wood an aluminum with smallish tools then a 24000 rpm asynchronous spindle and VFD as abound on Ebay
will be fine, I would suggest getting the largest your budget allows. 2.2kW is about the maximum that you can power
with a the single phase 230V supply.

This is an example, I have no idea about this company or anything else, I picked so you could see the type of
spindle I mean:

https://www.ebay.com/itm/CNC-80MM-ER20-2-2KW-WATER-COOLED-MOTOR-SPINDLE-AND-DRIVE-INVERTER-VFD-FOR-CNC-HY/262023137513?epid=1772185565&hash=item3d01cbc8e9:g:0A8AAOSwfVhaRbvk:rk:2:pf:0

Quote
i will use aluminum extrusion or aluminum plate with 15 mm thickness ,about 20 mm chrome shaft for holding. ball screw for 1.5 m side.

The extrusion and aluminum plate will determine the machines rigidity. Many have constructed machines with these
materials and are adequate. The 20mm shaft will need to be supported. If it were supported only at each end it would
flex badly. For a machine of the size you plan square linear rails and re-circulating ball loaded cars would be better.

This is an example of cheap Chinese linear guides (trying to behave as THK units!):

https://www.ebay.com/itm/2-sets-HSR15-1000mm-Linear-rail-Guide-4-pcs-HSR15CR-Square-block-bearing/262454933071?hash=item3d1b88764f:g:6jgAAOSwNsdXRt1T:rk:3:pf:0

Quote
it needs also a stepper one.

Why? Some of the low cost AC servo brands, while still more expensive than steppers, they are not that much more and
leave steppers in the dust performance wise.

Quote
by the way i want to use Siemens NX or Catia v5 which i familiar with. what is your opinion!

I have no idea what they are? This forum is about Mach3 and Mach4 both of which run on Windows OS Personal Computers.
You can induce a PC's parallel port to produce signals (via a breakout board) to control CNC machines. Regrettably the parallel
port has various limitations so it is becoming increasingly popular to use an external motion controller like an Ethernet
SmoothStepper or a UC300.

I use, and am very happy with Mach4 and an Ethernet SmoothStepper, and is my preference. Many other users will have equally
valid preferences, say Mach3 and a UC100 or UC300 or UC400.

Craig
My wife left with my best friend...
     and I miss him!
Re: CNC router specs
« Reply #5 on: February 19, 2019, 12:37:04 PM »
Just wondering how much experience the OP has in electronics, wiring and building CNC machines?
Retired Master Electrician, Commercial HVAC/R Service and lots of Hobbys.
Re: CNC router specs
« Reply #6 on: February 19, 2019, 03:05:48 PM »
sorry, what is OP ?
Re: CNC router specs
« Reply #7 on: February 19, 2019, 07:08:27 PM »
Hi,

Quote
Second, i want woodworking and aluminum so. and it will work heavy.
3D modeling will need tall tool, right? what about the spindle type and model ?

For wood an aluminum with smallish tools then a 24000 rpm asynchronous spindle and VFD as abound on Ebay
will be fine, I would suggest getting the largest your budget allows. 2.2kW is about the maximum that you can power
with a the single phase 230V supply.

This is an example, I have no idea about this company or anything else, I picked so you could see the type of
spindle I mean:

https://www.ebay.com/itm/CNC-80MM-ER20-2-2KW-WATER-COOLED-MOTOR-SPINDLE-AND-DRIVE-INVERTER-VFD-FOR-CNC-HY/262023137513?epid=1772185565&hash=item3d01cbc8e9:g:0A8AAOSwfVhaRbvk:rk:2:pf:0

Quote
i will use aluminum extrusion or aluminum plate with 15 mm thickness ,about 20 mm chrome shaft for holding. ball screw for 1.5 m side.

The extrusion and aluminum plate will determine the machines rigidity. Many have constructed machines with these
materials and are adequate. The 20mm shaft will need to be supported. If it were supported only at each end it would
flex badly. For a machine of the size you plan square linear rails and re-circulating ball loaded cars would be better.

This is an example of cheap Chinese linear guides (trying to behave as THK units!):

https://www.ebay.com/itm/2-sets-HSR15-1000mm-Linear-rail-Guide-4-pcs-HSR15CR-Square-block-bearing/262454933071?hash=item3d1b88764f:g:6jgAAOSwNsdXRt1T:rk:3:pf:0

Quote
it needs also a stepper one.

Why? Some of the low cost AC servo brands, while still more expensive than steppers, they are not that much more and
leave steppers in the dust performance wise.

Quote
by the way i want to use Siemens NX or Catia v5 which i familiar with. what is your opinion!

I have no idea what they are? This forum is about Mach3 and Mach4 both of which run on Windows OS Personal Computers.
You can induce a PC's parallel port to produce signals (via a breakout board) to control CNC machines. Regrettably the parallel
port has various limitations so it is becoming increasingly popular to use an external motion controller like an Ethernet
SmoothStepper or a UC300.

I use, and am very happy with Mach4 and an Ethernet SmoothStepper, and is my preference. Many other users will have equally
valid preferences, say Mach3 and a UC100 or UC300 or UC400.

Craig
what is the difference between 3 and 4 ?
NX and CATIA are CAM progs. like fusion 360 or ArtCAM. you can shape and generate G-Code with.
i know this spindle and may use it. and the rail is fine too.
some one told me that there are differences in electrical (like CNC interface) if you want 3, 4, 5 or 6 axis.
is it true ? which package should i use or DIY ?
Re: CNC router specs
« Reply #8 on: February 19, 2019, 09:51:57 PM »
Hi,

Quote
what is the difference between 3 and 4 ?

In one sense.....not much....they are both programs that use Gcode to control a machine.

Mach3 is still very popular, many people still use it and are very familiar with what it can and cannot do. All development
ceased on Mach3 five years ago. So whatever bugs it has it will always have.

Mach4 is a complete rewrite using an 'engineered' and modular approach. It is very capabale in most cases matching
Mach3 but in a number of areas it well and truly exceeds it.

If you have used neither Mach3 or Mach4 and want to start I would recommend Mach4. You can download both for free
and try them out in Demo mode.

Mach3 traditionally used a parallel port, and subject to certain limitations still does. External motion controllers like the
SmoothStepper and UC300 have meant that many of the limitations of the parallel port can be avoided.
Mach4 has a parallel port (Darwin) as well but is limited and will always be so, Mach4 was/is intended to be used
with an external controller. Thus when you consider the effective necessity of an external controller and that those controllers
are at this time limited to about five manufacturers many object to the perceived extra cost of Mach4.

Quote
some one told me that there are differences in electrical (like CNC interface) if you want 3, 4, 5 or 6 axis.

Some of the older parallel breakout boards (BoBs) were equipped to do in some cases three axes, in some cases 4 axes.
External controllers (strongly recommended) like the SmoothStepper and UC300 are regularly capable of six coordinated
axes and as many as another six out-of-band axes. Unless you choose old technology then multi axis controllers are
no problem.

Quote
NX and CATIA are CAM progs

Ok, never heard of them. If they have a post processor which can generate Mach compliant Gcode the it shouldn't be a
problem. Mach compliant Gcode is very close to Fanuc Gcode and its common to use a Fanuc post if a genuine
Mach post is not available.
My wife left with my best friend...
     and I miss him!
Re: CNC router specs
« Reply #9 on: February 20, 2019, 04:09:05 PM »
i will collect all this data and make a construction for the router and come bake.