thinfourth
pleb
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- 1,189
- Location
- Stonehaven
After getting a Ajax milling machine at a stupidly low cost i found myself with the issue of running it off single phase.
After using a variable frequency drive (VFD) on my lathe i decided to go down this route again. I hope this shows you roughly how to do it. if anyone is hugely stuck i will try and help as much as i can.
First pic is the side of the machine. The yellow switch is the original control which was simply a double throw switch with no starter with a relay and an overload in the old control box. With a VFD you need to bin the existing control system as the old system uses relays to control the 3 phase power. So to start the motor you just connect the motor directly to the 3 phase power which draws a metric crapload of amps due to how a motor works. A VFD gives you the 3 phase as you need it without any relays. It takes single phase and converts it into a DC voltage. it then takes this DC and chops it up into a 3 phase waveform at whatever frequency you want. To start the motor it starts at a low frequency and it increases the frequency until it reaches your desired max which reduces your peak amp draw.
the VFD i choose is this
https://inverterdrive.com/group/AC-Inverter-Drives-230V/Bosch-Rexroth-EFC3610-2K20-1P2-MDA-7P/
A bosch rexroth EFC3610 which has a removable remote display
manual here (Bosch-Rexroth-EFCx610-Manual) 10.6meg download
(remote panel removed to show fitting)
So to replace the yellow switch i have fitted 3 buttons. One for stop and one for start in either direction. This is then set up as a 3 wire control (mode 2). basically you have 4 terminals on the VFD one of which supplys 24V. One needs 24V constantly otherwise it will stop the VFD. The other two look for a pulse at which point they will start up the VFD. The stop button is normally closed the two green ones are normally open.
To the right of these buttons you can see the display which is remote mounted. This gives you control over the set-up parameters as well as the knob gives you control over the speed. if have set the lowest speed as 1hz and a max currently of 50hz so it gives me a 2nd way of speed control
For the lathe i used the existing switches if you are really interested then ask away.
if you look at the above pic you can see to the right of the machine is a small grey box where the old electrics live. this is basically dead. It stays there as it covers up part of the machine that is a different colour
To the left is a light grey box where the new stuff lives in
Big grey box to the right is the VFD for the main motor. The grey flat cable coming out is the cable to the remote panel
Small grey box middle is for the suds pump
Gold coloured box to the left is the transformer for the table feed motor (110v)
Along the bottom is a DIN rail with some DIN terminals
Also at the bottom is the RCD where the mains comes in.
switches on the door are double pole single throw
Left to right it is
Lights (yet to finish)
DRO which is a straight 240v feed
Feed which is 240v to the transformer and then 110V out
Now for the suds pump i have taken the yellow switch at the side of the machine and used this
It has 3 positions
position 1 is off, 2 is on and 3 is Auto
The main VFD has a relay on it so when it is running the relay closes and i use this to switch the small VFD on and off as the wee VFD is about £50 where as a single phase suds pump is about £90
I have spent about £350 ish on this including the box, the two VFDs, switches and other gubbins.
If anyone is utterly lost with electrics it is not impossible that i could build another one and post it off toy you
After using a variable frequency drive (VFD) on my lathe i decided to go down this route again. I hope this shows you roughly how to do it. if anyone is hugely stuck i will try and help as much as i can.
First pic is the side of the machine. The yellow switch is the original control which was simply a double throw switch with no starter with a relay and an overload in the old control box. With a VFD you need to bin the existing control system as the old system uses relays to control the 3 phase power. So to start the motor you just connect the motor directly to the 3 phase power which draws a metric crapload of amps due to how a motor works. A VFD gives you the 3 phase as you need it without any relays. It takes single phase and converts it into a DC voltage. it then takes this DC and chops it up into a 3 phase waveform at whatever frequency you want. To start the motor it starts at a low frequency and it increases the frequency until it reaches your desired max which reduces your peak amp draw.
the VFD i choose is this
https://inverterdrive.com/group/AC-Inverter-Drives-230V/Bosch-Rexroth-EFC3610-2K20-1P2-MDA-7P/
A bosch rexroth EFC3610 which has a removable remote display
manual here (Bosch-Rexroth-EFCx610-Manual) 10.6meg download
(remote panel removed to show fitting)
So to replace the yellow switch i have fitted 3 buttons. One for stop and one for start in either direction. This is then set up as a 3 wire control (mode 2). basically you have 4 terminals on the VFD one of which supplys 24V. One needs 24V constantly otherwise it will stop the VFD. The other two look for a pulse at which point they will start up the VFD. The stop button is normally closed the two green ones are normally open.
To the right of these buttons you can see the display which is remote mounted. This gives you control over the set-up parameters as well as the knob gives you control over the speed. if have set the lowest speed as 1hz and a max currently of 50hz so it gives me a 2nd way of speed control
For the lathe i used the existing switches if you are really interested then ask away.
if you look at the above pic you can see to the right of the machine is a small grey box where the old electrics live. this is basically dead. It stays there as it covers up part of the machine that is a different colour
To the left is a light grey box where the new stuff lives in
Big grey box to the right is the VFD for the main motor. The grey flat cable coming out is the cable to the remote panel
Small grey box middle is for the suds pump
Gold coloured box to the left is the transformer for the table feed motor (110v)
Along the bottom is a DIN rail with some DIN terminals
Also at the bottom is the RCD where the mains comes in.
switches on the door are double pole single throw
Left to right it is
Lights (yet to finish)
DRO which is a straight 240v feed
Feed which is 240v to the transformer and then 110V out
Now for the suds pump i have taken the yellow switch at the side of the machine and used this
It has 3 positions
position 1 is off, 2 is on and 3 is Auto
The main VFD has a relay on it so when it is running the relay closes and i use this to switch the small VFD on and off as the wee VFD is about £50 where as a single phase suds pump is about £90
I have spent about £350 ish on this including the box, the two VFDs, switches and other gubbins.
If anyone is utterly lost with electrics it is not impossible that i could build another one and post it off toy you