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Bush Flyer
28-12-2013, 01:23 PM
The time has come to replace my black & Decker router with another router or a spindle air cooled or water cooled. For me it is a bit of a mine field on what to pick, now I have a budget of not over 200 and I would prefer if it was less.
I manly cut up to 6mm ply and balsa but I do have one job to cut out some brackets from 6mm aluminium,
now I know that a spindle is a lot quieter but what size, the router I had was 600 watt will a 600 watt spindle do the same job. Would I be better going for water cooling and spending a bit more or will air cooling be just as good and what about VDF for control, there is a 1.5kw spindle air cooled with a 1.5KW VDF inverter for under 200 just add mounting. Or would I be better going for a 600Watt air cooled spindle with a power supply for Mach3 with mounting for under 150. considering my budget?
What would be the easiest way and best way considering my budget? Or should I just stick with the noise of a Router?

Mike.

GEOFFREY
28-12-2013, 02:29 PM
Forget the router and go with a spindle, but you should give serious consideration to the speed range you need. G.

Bush Flyer
28-12-2013, 02:42 PM
Thanks for the quick reply Geoffrey.
Ok spindle it is, the router is out. My old router speed was 30000 the spindles that I was looking at has there speed range 3000 to 12000 for the 600 watt and 24000 for the VFD and spindle all my bits are single flute and V bits.
What do you mean about speed range
what speed range should I be looking for?

GEOFFREY
28-12-2013, 02:50 PM
I was thinking about ensuring that the speed range for the spindle is suitable for the materials you are cutting. I don't know what the lowest speed the 24k spindle will run at, but that is probably your best bet. G.

Bush Flyer
28-12-2013, 03:16 PM
It doesn't say what the slow speed is on that spindle, but as you can see I cut mostly balsa and ply but I still have this 6mm aluminium to cut and There may be another job if this one works out.
What do you think about the min watts I could run. Also is the VFD easy to set up I see the reading are in Hz and I do not understand what Hz are in relationship to RPM?

GEOFFREY
28-12-2013, 04:05 PM
The relationship between frequency (cycles per sec. or hz) for the motor speed is cycles per minute (3000 at our mains frequency of 50hz) divided by the no. of pairs of poles on the motor. The motor will actually run at a slightly lower speed due to slip. I am fairly sure that is correct, but am talking from memory of of nearly 60 years ago!!! G.

EddyCurrent
28-12-2013, 04:07 PM
Also is the VFD easy to set up I see the reading are in Hz and I do not understand what Hz are in relationship to RPM?

rpm = (frequency (Hz) x 60 (seconds)) / number of pairs of poles.

so for example: a 4 pole motor connected to 50 Hz mains supply. rpm = (50 x 60) / 2 = 1500
This is the theoretical speed, the actual speed is rather less because the motor need 'slip' so it works out about 1425 rpm at the rated load.
My spindle is rated at 24000 rpm at 400 Hz so it must be a 2 pole motor

number of pairs of poles = (400 x 60) /24000 = 1, therefore number of poles = 2

edit: Geoffrey, looks like we both posted at the same time

EddyCurrent
28-12-2013, 04:17 PM
Thanks for the quick reply Geoffrey.
Ok spindle it is, the router is out. My old router speed was 30000 the spindles that I was looking at has there speed range 3000 to 12000 for the 600 watt and 24000 for the VFD and spindle all my bits are single flute and V bits.
What do you mean about speed range
what speed range should I be looking for?

I just checked here Cutting Speeds - LittleMachineShop.com (http://littlemachineshop.com/Reference/CuttingSpeeds.php#Milling)
and for a 6mm cutter is says about 2500 rpm for aluminium, I'm no expert on this though so just using the figures given. This implies you do need some speed control and 3000 may be a reasonable lower figure. Having looked at spindles, in some cases 24000 rpm is a special case in that it needs bearings to suite, 18000 rpm max. may be a cheaper route.

Also very important, the power of the spindle is usually quoted for max speed, so a 1.5kw 18000 rpm spindle would deliver 1.5kw at that speed only. At a lower speed it would be derated so would deliver considerably less. With this in mind and the fact you want to cut aluminium at low speed then a 1.5kw spindle would be the minimum I think.

Bush Flyer
28-12-2013, 04:18 PM
Thanks that helps. I have found a 800 watt spindle Frequency: 400 Hz speed 0-24000 R/Min with a 1.5Kw VFD in my price range and its water cooled would be nice and quiet. Would just need coolant pump Radiator and tank I think this is the way I will go if you think this would work for me?

Jonathan
28-12-2013, 04:38 PM
The spindle power output is roughly proportional to the speed, so at just 3000rpm you only get a fraction of the rated 1.5kW. The question to ask therefore isn't, 'what is the minimum speed the spindle will run at?', it's 'at what point is the power output of the spindle too low to be useful?'.

If the list of materials you are cutting is complete, then the 1.5kW spindle will be fine. The only thing it would struggle at is if you need to drill the aluminium, but if you've got a pillar drill that's clearly not a problem.


I just checked here Cutting Speeds - LittleMachineShop.com (http://littlemachineshop.com/Reference/CuttingSpeeds.php#Milling)
and for a 6mm cutter is says about 2500 rpm for aluminium, I'm no expert on this though so just using the figures given.

With a 6mm carbide cutter you'd use around 13000rpm.


Would just need coolant pump Radiator and tank I think this is the way I will go if you think this would work for me?

Yes and you wont even need the radiator if you have a good size tank of water/favorite solution.

Bush Flyer
28-12-2013, 04:45 PM
Many thanks for all the help this afternoon, I have just placed a order for a water cooled spindle and VFD, I will probably need help setting up, but I know where to come.
Thanks all again Mike.

Bush Flyer
31-12-2013, 07:17 PM
After reading more about VFD and after speaking to the supplier, I have changed my order to a Air cooled spindle and matching power supply that is simple to connect to MACH3. It will have more power than my old router with a lot more control, so at slower speed it will be quieter. It's all I need
I have been reading lots of problems with VFD in setting up and also one which overheated his new spindle to scrap after getting the setting wrong on the VFD and he had a electrician wiring it.
So I'm happy with the decision that I have made. Keeping it simple. Mike.

EddyCurrent
31-12-2013, 09:48 PM
After reading more about VFD and after speaking to the supplier, I have changed my order to a Air cooled spindle and matching power supply that is simple to connect to MACH3. It will have more power than my old router with a lot more control, so at slower speed it will be quieter.

Mike, How is the speed controlled ? does the motor have a two speed winding ?

Bush Flyer
31-12-2013, 10:24 PM
The speed is controlled by a potentiometer or connected to the breakout board, I think it has just 2 wires going to the spindle, But I have no seen it yet so could be wrong. The seller says that there are power from 230v to power unit then wire to the spindle and the 2 wires from the breakout board. Then 3 wires to the potentiometer from the power supply.
I will know better when it arrives.

JAZZCNC
31-12-2013, 10:39 PM
After reading more about VFD and after speaking to the supplier, I have changed my order to a Air cooled spindle and matching power supply that is simple to connect to MACH3. It will have more power than my old router with a lot more control, so at slower speed it will be quieter. It's all I need
I have been reading lots of problems with VFD in setting up and also one which overheated his new spindle to scrap after getting the setting wrong on the VFD and he had a electrician wiring it.
So I'm happy with the decision that I have made. Keeping it simple. Mike.

Sorry to say this but that was a mistake and in the long run I don't think it's any simpler because of limitations in use.
The VFD's are not hard to setup at all and ounce done that's it you never touch them again. For every one that have trouble there are 1000 that don't and even then it's not the VFD to blame but the user's lack of knowledge or care to make sure they have the correct settings. To fry one of these Spindles they would have needed to have it very wrong.!

Air cooled or Water cooled connecting to Mach is the same. Both will need speed control if you want to control speed from within the G-code. Both will need a relay to just control On/Off which your BOB will most likely have. The VFD has one built into it which can be programmed to come on or off with the spindle to control water pump or what ever you desire.

The thing the supplier may not have mentioned is the Duty cycle of the Air cooled spindle. The time can run the spindle before having to turn it off for a rest and cool down.!! . . The Cheap air cooled spindle if run at full speed will possibly need resting for 20-30mins every 2-3hrs and even the expensive Air cooled spindles will need resting 8-10hrs if run at full speed.
The WC spindles don't really have a Duty cycle and they run so cool they can be run at full speed for days without any trouble, mine often gets run for 12hrs none stop without even flinching.

Also because they are Air cooled they will have a fan just like a Router so will be noisy. WC spindles are much quieter and yes you still get same noise from cutter/material but even allowing for that they are much quieter than Air cooled spindles or routers.!!. . . Really Only those who have had Both can fully appreciate how much.!!

If possible I would reverse that decision.!!

Jonathan
31-12-2013, 10:52 PM
+1 to what Jazz has just said. You've made a mistake.

If the motor has got two wires then it's most likely a DC-motor, so 1830's technology... noisy, brushes that'll wear out and low efficiency (hence heat and potentially low duty cycle). It's also likely to have poorer quality bearings - might not even be angular contact, so the stiffness will be lower and who knows how long it will last.

Modelling Mike
02-01-2014, 11:29 AM
First post here and I have done the same as Bush Flyer, I ordered a dc spindle with power unit from Ebay. Well guess what I did this morning, after finding this thread, Yes you know it, I phoned the supplier this morning and cancelled my order I was lucky that he was happy to refund my money. Looks like I will have to read some more about spindles.

Bush Flyer
02-01-2014, 02:05 PM
I to have just cancelled my order again. And I won't be able to order there for a long time as it was that seller who advised me to buy the DC spindle and power unit. And when I tried to order the water cooled spindle and VFD as before, he said that there were none in stock at the original price. So have asked for a refund which will take seven days.
This will give me lots of time to decide what to buy.

JAZZCNC
02-01-2014, 02:24 PM
I to have just cancelled my order again. And I won't be able to order there for a long time as it was that seller who advised me to buy the DC spindle and power unit. And when I tried to order the water cooled spindle and VFD as before, he said that there were none in stock at the original price. So have asked for a refund which will take seven days.
This will give me lots of time to decide what to buy.

No surprise then he tried to talk you into the DC Spindle.!! . . . . . . . .But Don't worry about it because there are loads of suppliers quite willing to supply.!

You won't regret cancelling thats for sure.!

Lee Roberts
04-01-2014, 04:00 PM
First post here and I have done the same as Bush Flyer, I ordered a dc spindle with power unit from Ebay. Well guess what I did this morning, after finding this thread, Yes you know it, I phoned the supplier this morning and cancelled my order I was lucky that he was happy to refund my money. Looks like I will have to read some more about spindles.


I to have just cancelled my order again. And I won't be able to order there for a long time as it was that seller who advised me to buy the DC spindle and power unit. And when I tried to order the water cooled spindle and VFD as before, he said that there were none in stock at the original price. So have asked for a refund which will take seven days.
This will give me lots of time to decide what to buy.

There is a nice thread on the 2.2Kw spindles here if you havnt seen it yet: The 2.2Kw Chinese Spindles - Info, Setup and Advice + More (http://www.mycncuk.com/forums/routers-spindles-controllers/5814-2-2kw-chinese-spindles-info-setup-advice-more.html)

.Me

Bush Flyer
04-01-2014, 11:45 PM
Thanks for pointing out this thread it is very informative and anyone contemplating buying a spindle should read this first before spending any money, I for one will read it more that once before placing an order again.

Bush Flyer
09-01-2014, 10:13 AM
I have just ordered a VFD and water cooled spindle, Now to save cost and more important clutter I was thinking of just putting a large water tank under the table instead of a radiator and fan for cooling. How large a tank will I need? will 20 litres be large enough and how many litres a hour will the water pump have to pump to keep the spindle cool if worked hard like cutting aluminium? and if I ran antifreeze as coolant what percentage of antifreeze to water will I use?

Jonathan
09-01-2014, 11:36 AM
Cooling requirements greatly depend on how much power you draw from the spindle, but in general people use these spindles at well below their rated power, so you can get away without much to cool it. 20 litres should be fine - that's about what I use.

As for the pump, it's easy to calculate if you know how much power to dissipate, but knowing that is not so trivial. If you get something like this one it will be fine:

Aquarium Fish Tank Pond Submersible Water Pump 3000L/H | eBay (http://www.ebay.co.uk/itm/Aquarium-Fish-Tank-Pond-Submersible-Water-Pump-3000L-H-/111250655097?pt=UK_Pet_Supplies_Fish&hash=item19e70e4779)

Bush Flyer
09-01-2014, 01:28 PM
Thanks Jonathan, I've put the pump on my watch list, but will try to get a new one first, all parts are coming from the UK except the spindle mount but I am waiting on a reply from a supplier in the UK to get back to me so should not be to long and I will be back up and running all going well.

Bush Flyer
10-01-2014, 01:05 PM
I'm about to order wiring for the new spindle and was wondering should I buy CY 4 core 1.5mm cable for the spindle and CY 3 core 1.5mm cable for the power to the inverter or could I reduce the cable down to 1mm. I have been looking for a diagram for the wiring and have found some very conflicting diagrams, but I could not find one diagram with cy cable and where to connect the shield then I found one site saying do not use cy cable for mains connection the more I read the more confused I am getting so I will rely on what is said here.

The VFD is 1.5kw HUANYANG VARIABLE FREQUENCY DRIVE.
The motor is a, Germany Imported Bearing, water cooled spindle 0.8Kw

The best information that was pointed out to me was this thread http://www.mycncuk.com/forums/routers-spindles-controllers/5814-2-2kw-chinese-spindles-info-setup-advice-more.html
But it did not tell me if I should use CY cable to power the VFD and it did not show the earth and the shield wire.
This is the cable calculator that I used with a 3% volt drop. http://quickbit.co.uk/swa-cable-calculator.html and it always comes out at 1.5mm ?

I apologise for asking simple questions, but wiring and setting up of this is out my comfort zone.

Clive S
10-01-2014, 03:05 PM
I have used cy cable 1mm 4 core from the inverter to the spindle, 3 cores are for driving the spindle and the fourth core is to earth (my spindle has a 4 pin socket on it) on mine pin 4 was not connected to anywhere, I took the top off and soldered a wire from pin 4 to one of the socket mounting bolts on the spindle (I had to put a longer bolt in and then use a nut on the inside).
The shield on the cy cable is only earthed and the inverter end.
The mains cable to the inverter only need 1mm standard 3 core flex. ..Clive

Jonathan
10-01-2014, 03:21 PM
The mains cable to the inverter only need 1mm standard 3 core flex. ..Clive

Additionally, since we know that 3-phase power transmission is more efficient than single phase, that shows we can use a bit less than 1mm^2 cable from the inverter to the spindle. However the cost difference is likely to be negligible over such a small length, so I wouldn't worry too much. I used the same 1.5mm^2 4-core CY cable for my stepper motors and spindle, simply because at the time obtaining a reel of that cable was more cost effective than getting a smaller length of two.

Clive S
10-01-2014, 03:51 PM
Additionally, since we know that 3-phase power transmission is more efficient than single phase, that shows we can use a bit less than 1mm^2 cable from the inverter to the spindle. However the cost difference is likely to be negligible over such a small length, so I wouldn't worry too much. I used the same 1.5mm^2 4-core CY cable for my stepper motors and spindle, simply because at the time obtaining a reel of that cable was more cost effective than getting a smaller length of two.

I have use 1mm for the spindle and steppers as they are only 3-4mtr long and fit the plugs better .. Clive

EddyCurrent
10-01-2014, 04:23 PM
I would have a look at various manuals for major inverter manufacturers to see what they say, these can be viewed or downloaded as pdf's.
For example an ABB manual says for 1.5kW the input cable should be 2.5mm^2, motor cable should be 1.5mm^2

"Motor cables
(recommended for input cables also)
Symmetrical shielded cable: three phase conductors, a concentric or otherwise
symmetrically constructed PE conductor and a shield

Note:
A separate PE conductor is required if the conductivity of the cable shield is not
sufficient for the purpose"

So in terms of CY cable that's 3 core cable for the motor using the outer as the earth conductor and screen, this should be connected at both ends to obviously act as an earth conductor and to give 360 degree connections for EMC shielding (that's what CY glands are for). If the CY screen is of less cross sectional area than the inner conductors then another core should be used for the earth, i.e. 4 core cable or a separate earth cable run on the outside.

The supply cable could be 4 core armoured.

Before anyone jumps on the well known idea about connecting screens at one end only I suggest you do a search for EMC cable screening first.

Jonathan
10-01-2014, 04:35 PM
Bear in mind that ABB's recommendations for cable size are probably trying to cover themselves for most applications, whereas our application is quite specific. For the motor in question, the cables are quite short and the motor will spend most of its life operating well below the rated power. I therefore wouldn't be concerned with recommending 1mm^2 cable in this instance.



Before anyone jumps on the well known idea about connecting screens at one end only I suggest you do a search for EMC cable screening first.

+1 :)

EddyCurrent
10-01-2014, 04:46 PM
Bear in mind that ABB's recommendations for cable size are probably trying to cover themselves for most applications, whereas our application is quite specific.

Jonathan, I fully understand what you are saying but it's a bit like the DIY person who installs a new 13amp socket outlet using a bit of 3 core flex because he only wants to plug a table lamp into it. They sell the house and next owner plugs a 3 bar electric fire into it.

Clive S
10-01-2014, 05:04 PM
The supply cable could be 4 core armoured.
Eddy Do you not think that this is a bit OTT as on these type of VFD's there is not the provision to connect wire armoured cable with a separate box. I don't know of anybody in a DIY situation that would use it. Just my two cents worth:beer: ..Clive

JAZZCNC
10-01-2014, 05:28 PM
This is going to sound rich coming from ME but come on Lads don't turn it into an argument and pyshics lesson so to confuse the Man.

Bush Flyer 1.0mm/2 is fine for these Spindles and what I've fitted many times without any issues even on heavy use machines but if you want to cross I's & Dot the T's then use 1.5mm/2.

2.5mm/2 for the VFD Input. If near heavy traffic or chance of damage etc then armoured if not then just use 2.5 Flex not ridged mains cable.

Bush Flyer
10-01-2014, 06:11 PM
Right 1.5mm/2 cable for the spindle and normal 3 core for the mains but the size I was going to buy 1.5mm/2 cable as that can handle 15amps, and a wall plug is only 13amps.
2.5mm/2 would be able to handle 20amps but still the wall plug is only rated at 13 amps.
Or have I got to take the main feed straight from the fuse box to get 45amp supply in the house ( I hope not.)

Jonathan
10-01-2014, 06:16 PM
2.5mm^2 for the VFD input is excessive. 1mm^2 is adequate...so if you want peace of mind go for 1.5mm^2!

It's a 1.5kW spindle, so anything above that and the VFD will cut out within a few seconds - i.e. too fast for the cable to heat up, so you only need to rate the cable for 1.5kW. 1500/230=6.5 amps, hence 1mm^2 (rated for 10 amps) is plenty for a 1.5kW spindle and just enough for 2.2kW as 2200/230=9.6A.

JAZZCNC
10-01-2014, 06:45 PM
It's a 1.5kW spindle, so anything above that and the VFD will cut out within a few seconds - i.e. too fast for the cable to heat up, so you only need to rate the cable for 1.5kW. 1500/230=6.5 amps, hence 1mm^2 (rated for 10 amps) is plenty for a 1.5kW spindle and just enough for 2.2kW as 2200/230=9.6A.

Didn't realise it was 1.5Kw spindle so yep 1.5^2 fine.

EddyCurrent
10-01-2014, 07:38 PM
Eddy Do you not think that this is a bit OTT as on these type of VFD's there is not the provision to connect wire armoured cable with a separate box. I don't know of anybody in a DIY situation that would use it. Just my two cents worth:beer: ..Clive

It's recommended that the supply cable also has a screen so I was meaning the supply cable to the control panel enclosure which I assumed would be metal and wall mounted. Just because people keep saying it's DIY I'm not into dumbing things down. I would suggest the supply be fed by a 16 amp minimum supply, if you want a plug and socket then it's the blue type.

Bush Flyer
10-01-2014, 07:55 PM
Right that's it sorted, I have ordered 4 core 1.5mm/2 screened and 1.5mm/2 normal 3 core mains.
Thanks for all your help, once I have it set up and I run into problems I will probably need your help again.:thumsup:

Clive S
10-01-2014, 08:18 PM
From your post #25


The VFD is 1.5kw HUANYANG VARIABLE FREQUENCY DRIVE.
The motor is a, Germany Imported Bearing, water cooled spindle 0.8Kw

I take it your spindle is 0.8Kw .. Clive

Jonathan
10-01-2014, 08:28 PM
From your post #24

I take it your spindle is 0.8Kw .. Clive

Ahh, this is the point where you consider Eddy's post #31:


Jonathan, I fully understand what you are saying but it's a bit like the DIY person who installs a new 13amp socket outlet using a bit of 3 core flex because he only wants too plug a table lamp into it. They sell the house and next owner plugs a 3 bar electric fire into it.

We wouldn't want someone to change the 800W spindle to 1.5kW and potentially melt the 0.75mm^2 wire that would be fine for the former...

Bush Flyer
10-01-2014, 08:31 PM
Yes the spindle is only 0.8Kw but most of the cutting I will do is balsa and up to 6mm birch ply. I could have bought a 1.5Kw spindle for less money with a 1 year warranty but the bearings had only 6 months warranty. So I went for a certificated german 4 bearing spindle with a two year warranty including the bearings so no worries for 2 years and the vfd has a 3 year warranty.

EddyCurrent
10-01-2014, 08:46 PM
One of the worst things with electrical systems is that as long as they are working everyone thinks they must be okay. Also with regard to the VFD and spindle, they would still work with speaker cable. It's only when things go wrong that the difference between a proper installation and something less becomes evident.
Of course as people keep saying it's only DIY so we can just do whatever we want.

Bush Flyer
21-01-2014, 12:18 PM
Well after fitting up my new spindle and VFD with shielded cable which turned out to be easier than I thought. I have turned a good running machine into one that has lots of Interference with e stops and missed steps. :grey:

Now I know I built the machine with normal wire ( not shielded ) but I was told after it was all wired and ready to plug in that it should have been wired with shielded cable, So now I have to rewire it.
Now just to check 0.75mm/2 4 core cable for the stepper motors and 0.75mm/2 2 core cable for the limit stops. Is the anything else that I need before sending a order off?
Do you have to fit shielded wire from the power supply to the breakout board and to the drivers and the drivers to the breakout board or is it just the limit switches and the stepper motors?

EddyCurrent
21-01-2014, 01:45 PM
Generally where there is high frequency you need screening, so that means from PC to bob, bob to stepper drivers, stepper drivers to stepper motors, VFD to spindle motor.
I used CAT5 twisted pair for the bob to stepper drivers, CY cable for stepper drivers to stepper motors, CY cable from VFD to spindle motor. Some have said that CAT5 is not flexible enough to run through the energy chain but that depends on the bend radius you have and the type I'm using is stranded not single core.( CAT5 bend radius it's usually considered to be 4x the diameter). Failing that a different twisted pair flexible cable would do. I also used the same twisted cable for the limits as I bought a roll of it, it's the twisting that helps it reject noise.

It's a double edge sword, on one hand you are trying to prevent interference entering the cable and on the other hand you are trying to prevent interference escaping the cable. In general for the first issue screens have been connected at one end only and usually at the same point, hence the term star earthing. For the second issue screens are connected at both ends to meet the EMC regs. So with that in mind are your cables interference generators or receivers, I would say they are all generators except for the limits which are receivers. This implies screens are connected at both ends for everything other than the limit cables. At least then if you do suspect problems you can simply disconnect one end of the screens to see if it helps.

This is worth a read
http://www.nexans.co.uk/eservice/UK-en_GB/fileLibrary/Download_540239149/UK/files/FTP%20vs%20UTP_V5_GBA_HFO%20DWI2%20NR3_PBE_V2_1.pd f

Though aimed primarily at music applications this is also a wothwhile read.
http://www.phmusic.co.uk/pharri5833/oneend.htm

Bush Flyer
21-01-2014, 03:25 PM
Thanks Eddycurrent,
I have my spindle screen connected at the VFD end only, should I connect the screening at both ends the VFD and the spindle?
I did twist all wiring when I built the CNC router as I knew this helps with screening but since I am going to totally rewire it I am going to make sure that it is properly done so that there is no chance of interference again.
Another question is, there is eight wires at the stepper motor four pairs, there would be no screening the last few inches or would you add some screening or will it matter for the last few inches?

EddyCurrent
21-01-2014, 04:05 PM
Any VFD manual will show the motor screen connected at both ends.

Generally it's okay to have the last few inches unscreened becasue somehow you have to get the individual cores into their respective terminals, but you could use something like this
30504 - WURTH ELEKTRONIK - SLEEVING, COND-NYLON, PER M | Farnell UK (http://uk.farnell.com/wurth-elektronik/30504/sleeving-cond-nylon-per-m/dp/1909674)

Most people use Gremflex just to keep it tidy.

If screened cable is not going to be terminated into a special gland made for the purpose I like to use about an inch of heat shrink sleeving at the end, 1/2 onto the outer sheath of the cable and 1/2 over the inner cores, this keeps the end of the screen tidy and stops it fraying or straying. Mostly it's a good idea to solder a short piece of wire to the screen at the end, this joint is hidden under the heat shrink and makes for an easy way to terminate the screen.

Bush Flyer
21-01-2014, 07:06 PM
Just to get this clear.
I have used CY 4 Core 1.5mm/2 cable from the VFD to the spindle, But I need to connect the screen to earth not just at the VFD but also at the spindle.
I will fit CY 4 Core 0.75mm/2 cable from the drivers to the stepper motors also the screen will be earthed at the driver end at a star end earth point and at the stepper motor end.
I will fit CY 2 Core 0.75mm/2 cable from the breakout board to the limit switches with the screen earthed at the breakout board, but the screen not connected at the switches.
I could use CY 4Core cable between the breakout board and the stepper motor drivers also the screen earthed at both ends.
All ends will be joined to a common earth point in side the CNC control unit.
Should I also run a earth cable between the control box and the CNC machine?
And I will get some sleeving to make the ends tidy, I like that idea.

EddyCurrent
21-01-2014, 10:13 PM
Just to get this clear.
I have used CY 4 Core 1.5mm/2 cable from the VFD to the spindle, But I need to connect the screen to earth not just at the VFD but also at the spindle.

Yes


I will fit CY 4 Core 0.75mm/2 cable from the drivers to the stepper motors also the screen will be earthed at the driver end at a star end earth point and at the stepper motor end.
Yes


I will fit CY 2 Core 0.75mm/2 cable from the breakout board to the limit switches with the screen earthed at the breakout board, but the screen not connected at the switches.
Yes


I could use CY 4Core cable between the breakout board and the stepper motor drivers also the screen earthed at both ends.
Yes if the diameter is sensible to do so.


All ends will be joined to a common earth point in side the CNC control unit.
Yes, The idea is to ensure there are no voltage differences between any of the screens so a star point is the best way to achieve it.


Should I also run a earth cable between the control box and the CNC machine?
Yes the machine must be earthed for safety reasons.

Like I mentioned earlier if you subsequently have any problems related to this you can always disconnect one end of a screened cable to see if it improves.

Bush Flyer
21-01-2014, 10:27 PM
Hi EddyCurrent many thanks for taking the time to help with my simple questions, I can now sort this wiring with confidence now.

EddyCurrent
21-01-2014, 10:33 PM
In addition any cables going to a motor, stepper or spindle, should be physically separated from the other signal cables as much as possible and it's not too bad if they cross at right angles, running them parallel is the worst. Of course this is difficult to do especially in the energy chain.

JAZZCNC
21-01-2014, 11:31 PM
If you want to try a potential quick fix for false trips then try playing with de-bounce in Mach3 Config.

No substitute for correct wiring but it may get you going untill your ready to re-wire.?

navins
27-02-2014, 01:27 PM
Don't allow much pressure means voltage will be because of high voltages, this died.
Add capacitor.

Washout
08-03-2014, 11:22 PM
Eddy (and others),

The topic of earthing and prevent loops is something, which I have struggled mentally with since I built my machine and thought I had it sorted until your extensive post on page 5 of this thread. Also what I have done may be correct for my circumstances, so just to check:

Firstly my machine is all metal and I have good conductivity right from the cutter tip to the bed (including through the spindle and bearing etc.). Initially when I built the machine I did think I needed to earth the driver/stepper CY cables back to the star point in my control box only (and from that to mains earth) with a separate earth strap from machine to control box star point and also to have the spindle earthed through the spindle cable shield back to the VFD earth point (and again from there to mains earth).
.
However I was getting a lot of spurious e-stops and when I disconnected the earth strap from the machine and essentially relied on the spindle to VFD earth they went away i.e. my machine is only earthed at one point in the VFD whilst all the stepper cables are only attached at the control box star point.
.
In light of your post I'm questioning that again and would welcome an opinion especially as I also use a circuit making touch plate and cutter when setting tool height/z zero.

EddyCurrent
08-03-2014, 11:45 PM
This also mentions plasma machine requirements, I'm not familiar with plasma machines.

CNCCookbook: Dealing with noise problems (http://www.cnccookbook.com/CCCNCNoise.html)

JAZZCNC
09-03-2014, 12:10 AM
However I was getting a lot of spurious e-stops and when I disconnected the earth strap from the machine and essentially relied on the spindle to VFD earth they went away i.e. my machine is only earthed at one point in the VFD whilst all the stepper cables are only attached at the control box star point.


This indicates you have some issue in some other area on the machine or in control box as doing this as just side tracked the problem not cured it.
Noise is a bear to find You could try taking a earth wire from the spindle body back to Earth on the VFD this will ensure the gantry is earthed at least and probably the rest of machine if bearings don't isolate the rest of frame but still not create earth loop as it's not connected to Star point in control box.

Have you measured frame with a meter to see if it's putting out voltage.?

EddyCurrent
09-03-2014, 12:59 AM
When you look about some people say connect the screen at both ends some one end this is why I mentioned earlier that if connected at both ends and there is a problem it would be easy to remove one end to see if it improved. VFD manuals show the motor screen connected at both ends but in addition an earth cable is also required, ideally this will ensure that both ends of the cable screen are at the same potential. Screens should not be used as earth connections, metal parts should be connected to earth at a star point for safety reasons. Loop currents flow because there is a difference in potential at each end of the cable, this is due to long cable runs and earth wires of minimum cross section. There is also the issue of earthing the negative side of DC supplies and also connecting them together, again some say this is good while others say it is bad.

http://ecmweb.com/content/avoiding-pitfalls-powering-cnc-equipment

m_c
09-03-2014, 01:42 AM
The big issue is avoiding the creation of ground loops near control loop wiring.
There is also the issue of distinguising between earthing, and grounding.
If you look at commercial machines, they usually have seperate earth and ground points. All sheilding goes to earth, with ground being your negative power supply point.
.
I know that on my old lathe, the stepper wiring is unsheilded, and the only issue I got was when I connected the spindle sensor shield to the star point. I cut the wire to the sheilding, and never had a problem since (other than the usual usb SS communication issues!)
On my new lathe, I've kept it mostly as it was. All sheilds/earth points go to the earth terminal block, with all the power grounds going to the relevant ground bar. However it also uses 24V sensors/switches with differential encoders, so it should be very interference proof anyway. The mill will also be using the same setup once I get around to getting it going.