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Desertboy
11-05-2017, 10:21 AM
Hi building a machine with 1/3 sheet of ply build area out of t slot extrusion with 25mm supported rail on 1 axis, hiwin on the other and Z will be 25mm smooth rod and 20mm ballscrew. Nema 23 powered.

A lot of what I will do is cutting/milling parts from mdf or aluminium to vac form from. Normally it will be MDF but occasionally Aluminium depending on the desired life span of the mold.

I need a spindle obviously but bit confused on what to buy? I want to cut ply, mdf & aluminium at a decent rate and the spindle will be worked 20-30 hours a week. I need something to get me working now and once I've done a couple of jobs for a customer I can afford to get a decent one from Zapp and keep the Chinese one as a spare.

1. I have no idea what sort of power I want, is it a case of more power quicker cutting?
2. From what I read on here it wants to be water cooled and that I should use my own water pump (I have loads), so I will go with water cooled this is 0 hassle to me.
3. Speed control, not sure what a VFD is some kind of power inverter I assume that performs PWM but what's the difference between a VFD and a spindle that supports PWM through Mach 3 (With appropriate circuitry)?
4. Collet size?

I was eyeing up this one
http://www.ebay.co.uk/itm/2-2KW-WATER-COOLED-SPINDLE-MOTOR-AND-INVERTER-VFD-ENGRAVING-MILL-GRIND-MILLING-/260626018545?hash=item3cae8570f1:g:5o8AAOSw-W5Us1mz

The 4 german bearing thing most of they claim how true is it?

I'm guessing it's pot luck on quality.

My friend gave me a brand new router to fit but when he turned up with it I burst out laughing as it's one of these lol

https://www.ebay.co.uk/p/?iid=232188872055&&&adgroupid=41810622899&rlsatarget=pla-295457564841&abcId=1058856&adtype=pla&merchantid=101761631&poi=&googleloc=9046185&device=c&campaignid=797426840&crdt=0&chn=ps

Thanks

magicniner
11-05-2017, 12:01 PM
3. Speed control, not sure what a VFD is some kind of power inverter I assume that performs PWM but what's the difference between a VFD and a spindle that supports PWM through Mach 3 (With appropriate circuitry)?


A Variable Frequency Drive (VFD) takes the input power, rectifies it (sometimes transforming voltage first) and then uses electronics and big capacitors to chop up the DC and feed it out in little pulses which with the aid of the smoothing capacitors approximates 3 phase well enough that the induction motor doesn't know any different .
PWM works for permanent magnet and universal 3 phase mains motors and also for DC motors, any power tool with a knob for varying the speed is likely to be using PWM.

routercnc
11-05-2017, 01:25 PM
Hi Desertboy,

You might be mixing things up in your post, not sure. So here is my understanding of how it works and what you need. Water cooled spindle is not like a router. You need a VFD (invertor) to connect it to which is why that ebay link shows them as bought as a package.

The speed control is done inside the VFD and can either be:
option 1. Via buttons on the front panel (tedious, but works to get you going)
option 2. Via an external 10k pot wired to 2 special control terminals under a small cover on the VFD (this is very cheap and simple to do so don't worry about that for now)
option 3. Via Mach3 which talks to the VFD through an interface board. This can be added later so again don't need to worry about it in terms of spindle selection. My understanding here is that this can be PWM signal or a 0-10V signal.

Spindle power should be at least 1.5kW (although I think Boyan has used 0.8kW for certain applications?), but ideally 2.2 kW. You get more power/torque which helps at lower speeds as these things are direct drive and they will stall out if you push them and the rpms are low. But the main reason for going 2.2 kW is that the collet is ER20 instead of ER16. This means it will take tools of up to 12mm instead of ~6 mm which is a big bonus. 6mm to 8mm or even 10mm is a big increase in tool stiffness so will help with the roughing out. I've heard 1.5kW can occasionally come with ER20, but I would go for the 2.2kW anyway.

I can't help on the German bearing quality question but I suppose the reality is you either take a punt on these generic Chinese machines, or save up (quite a lot!) for the HSD Italian type stuff.

I also started many many years ago with a router on the machine and it is very noisy, plus I suspect the run out on the collet way more than 0.05 mm, and the duty cycle on a router would not like running the extended jobs a CNC machine will typically run for. If you are in any way serious about a CNC machine give them a miss. Same goes for the Kress spindles.

Clive S
11-05-2017, 02:59 PM
You can also fit a pot internal to the front panel as;- #1 http://www.mycncuk.com/threads/7388-Fitting-a-pot-to-a-Chinese-Spindle-VFD

Desertboy
13-05-2017, 01:16 PM
Nice one for the advice I am going to go with a 2.2kw with 4 bearings and a VFD as my starter spindle and the price from Germany is very similar to from China but delivery times are better obviously and no import tax. Hopefully I can order it some time next week but my ballscrews are in Stanstead now so have to see how much they screw me for import tax first.

I can handle wiring a pot in ;)

Desertboy
13-05-2017, 01:20 PM
You can also fit a pot internal to the front panel as;- #1 http://www.mycncuk.com/threads/7388-Fitting-a-pot-to-a-Chinese-Spindle-VFD

Nice mod I've recovered a start/stop, emergency stop box to use with my machine I'll fit the pot into that box I think as it's as close to a control box as I will have lol.

For now the machine is only going to be driven by an Arduino but when it's actually working and usable I'm going to buy some 1/2 decent stepper drivers and a breakout board and use either mach 3 or EMC2.

I've been a linux user for almost 10 years so EMC2 makes a lot of sense to me but I do have windows if needed. (Had to keep it for cad)

Ger21
13-05-2017, 01:52 PM
option 3. Via Mach3 which talks to the VFD through an interface board. This can be added later so again don't need to worry about it in terms of spindle selection. My understanding here is that this can be PWM signal or a 0-10V signal.

Mach3 or LinuxCNC outputs a PWM signal, which is then converted to 0-10V which is fed to the VFD. You need a spindle controller or breakout board that does this. You can also get controllers that convert step/dir to 0-10V. Someone at CNC Zone just used a step/dir signal to a Hitachi VFD to control it directly.
You can also use Modbus to control the VFD.
Lots of different options.

Boyan Silyavski
14-05-2017, 12:57 AM
2.2kw is the standard for a nice machine. And no need to upgrade as they are quite reliable. If you buy from reputable seller and receive GPZ brand spindle, yes, they are 4 bearing. spindle is best controlled from board. The more "auto" the better in the long run.

Why dont you take a step back and explain your axis decisions? if you have not bought the screws and supported rails.

First of all Hiwin 20 is enough and best for the purpose. Secondly the Z and the X/ gantry are quite more important than the long axis /Y and A/ . So if not gonna be used square rail on all machine, then better be used on Z and X.
Also 20xx screw for Z is overkill, 1605 is best there and 1610 for the X.

There are many threads in the forum where all is explained again and again..., so may be some homework?

Desertboy
14-05-2017, 01:47 AM
Hi Boyan,
I've read a lot of your posts and seen some of your builds and so I know I would be wise to listen to your advice.

I try not buy things if possible lol the z axis will be made with this
21622(Once I have it rebuilt) I have 25mm smooth rod with bearings as well.

which cost me 1 days very hard work stripping it out a machine (I got 3 of them) but no actual money just hard work ;)

I'm using 25mm supported rail on 1 axis because I got it for free and 15mm hi win on the other axis because 1.5m with 4 blocks on 2 rails was 99 delivered.

This is a cheap hack machine lol but I do intend to pimp it up or just build another one I have more t slot and sometimes I get get rails to scrap ;) so we will see.

Boyan Silyavski
16-05-2017, 07:33 AM
Free stuff is the best stuff :joker:

Desertboy
16-05-2017, 07:49 AM
Free stuff is the best stuff :joker:

Too true

https://www.aliexpress.com/item/Hig-quality-Linear-Guide-1pcs-TRH25-Length-1800mm-Linear-guide-rail-2pcs-TRH25B-linear-slide-block/32796651547.html
looking at this on alixpress when I build another one (I want 8*4 capability) I think I should just use these all round at this sort of price unless I'm particularly lucky with the next machine that comes in.

I was thinking the best thing to do with the supported rail is to use it until it becomes an issue then keep the rail and bearings for a table saw slide to make cutting 8*4 a joy.

Although I want at least one axis to have 3m rails.

So going to cost a 1000 by the time the import tax man has his fingers in the tills lol.1

Boyan Silyavski
16-05-2017, 02:47 PM
Too true

https://www.aliexpress.com/item/Hig-quality-Linear-Guide-1pcs-TRH25-Length-1800mm-Linear-guide-rail-2pcs-TRH25B-linear-slide-block/32796651547.html
looking at this on alixpress when I build another one (I want 8*4 capability) I think I should just use these all round at this sort of price unless I'm particularly lucky with the next machine that comes in.

I was thinking the best thing to do with the supported rail is to use it until it becomes an issue then keep the rail and bearings for a table saw slide to make cutting 8*4 a joy.

Although I want at least one axis to have 3m rails.

So going to cost a 1000 by the time the import tax man has his fingers in the tills lol.1

Exactly these ones i had problem with. I had just one sample though. Check Robodig ones, they seem better to me