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Help required re: centec 2b motor replacement

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peter Humphreys 219/01/2014 20:26:22
10 forum posts

Hi all, lat august I bought a very used but working centec mill, a little while after I bought it the motor gave out, not unexpected but not helpful either, anyway, I removed the motor and had it looked at by a motor rewinds company close to me, a couple of weeks ago they admitted that they had lost my motor, only issue now of course is I have a perfectly good mill but no motor to drive it. I'm hoping that someone here will be able to point me in the rift direction or may even have a suitable candidate hiding away in their workshop or loft.

So please if you could help it would be very much appreciated.

jason udall19/01/2014 20:50:33
2031 forum posts
41 photos
Would have thought a rewind company is better placed to source you a motor...at very good price..
peter Humphreys 219/01/2014 20:55:08
10 forum posts

Thanks for the reply. Your right, but I'm a bit reluctant to part with anything especially money if it's going to a rewind company, the main issue being that the motor was an imperial one that ran in both directions via the operation of a barrel switch, I'm hoping some one has a spare one to be honest.

jason udall19/01/2014 21:00:26
2031 forum posts
41 photos
Ahh...Maybe I should have said..THE rewind company...they have after all lost yours...

Edited By jason udall on 19/01/2014 21:02:04

peter Humphreys 219/01/2014 21:08:38
10 forum posts

Yep you'd think so wouldn't you? They have been a complete waste of time and effort, it's taken till now for them to even admit that there was a problem, I intend on replacing the motor myself and then presenting them with a bill and the threat of legal action as I can't see this being resolved any other way. Unfortunately!

jason udall19/01/2014 22:19:35
2031 forum posts
41 photos
Ahh .
Can't help with motor..
Can you at least specify the old motor. .
Ie , hp shaft dia , rpm , 3 or single phase ..mounting..but I guess this isn't recorded since you were getting motor rewound...lesson for us all
peter Humphreys 219/01/2014 22:25:17
10 forum posts

Yep the only things I know about the motor are that it was single phase and side mounted with a v belt pulley, I think that it's rpm was around the 1500 mark, from what I can gather from info on the internet it was about 1.5hp, as for shaft diameter or any other specifics I can't even guess, the lesson here being take pics and details before you remove any items to be sent away or run the risk of having a very expensive door stop.

jason udall20/01/2014 09:35:41
2031 forum posts
41 photos
Bugger..guess you have lost the pulley too...
Gary Wooding20/01/2014 10:08:25
932 forum posts
236 photos

The Centec mills were small industrial machines which were fitted with 1hp 1500rpm 440v 3ph motors. The 220v 1ph that you had is not original - as far as I know, the 2B (mine is a 2B) has the spindle motor in the cabinet - not mounted on the side. I believe some older Centecs had a side mounted motor, but I'm pretty sure it would have been 3ph too.

My advice would be to use a delta wound 3ph motor from a VFD - you will never regret having continuously variable speed and instant reverse. It's great for power tapping.

If you want details, just drop me a line.

peter Humphreys 220/01/2014 16:33:06
10 forum posts

Bugrit! Turns out I was talking rubbish it's a 2a that I've got not a b!

i want to keep it 240v, don't have the know how or will power to change it, and to be fair right up till the motor started to display problems there was no lack of power or speed so it seems the motor was up to the job, just getting on in years is all.

Alan .20420/01/2014 16:46:55
304 forum posts
14 photos

Get in touch with Gary he's a mind of info on the 2B and I can't see the 2A being a deal different, personally I would go foe a three phase 1.5hp 1450ish rpm motor running through an inverter, you won't regret it.

Al.

ash roberts04/05/2015 21:28:43
6 forum posts
3 photos

Hi guys,

i have a lovely Centec 2B that i need to start using..

I managed to delta the main spindle motor using a Drives direct VFD.

I also took the table motor from the main power feed and it now has its own and VFD

Now i need to convert the table motor to Delta and could do with some advice please.

I think the original table motor is still on it..

BHP - 0.125

RPM - 1425 Dual voltage 3 phase.

colours are

A - RED + DARK RED

B - GREEN

C - BLACK + DARK BLUE

N - BLACK +BROWN + DARK BROWN

NO WIRE CONNECTED TO THE EARTH ?

I am correct in thinking i wire the three phases into A B C one each but link 1-2 , 2-3 & 3-1?

Any advice would be appreciated.

img_7435.jpg

duncan webster05/05/2015 10:18:56
3710 forum posts
69 photos

2B motor is mounted inside the cabinet under the machine. When fitted with single phase motor they tend to be very noisy as the cabinet acts as a sounding board. When mine died I fitted a three phase motor and it transformed it, sweet as a nut now. Fitting the motor is something else, I eventually managed it using loads of wooden packing and a car scissor jack.

I still have the old motor, its centrifugal switch is blown otherwise it's OK. It could be made to work with a manual start button, if it's any interest give me a PM

Les Jones 105/05/2015 12:37:50
2244 forum posts
153 photos

Hi Ash,
Remove the three wires from the N terminal and make sure they are not touching each other or anything else. Verify with your multimeter that there is no continuity between terminals A, B, and C. (If there is then disconnect the power wires to the motor and do the test again. If you still get continuity then I don't know how the motor is connected.) Identify the wire that you disconnected from terminal N that shows continuity to terminal A and mark it to be connected to terminal B. (But DO NOT connect it to terminal B yet.)
Identify the wire that you disconnected from terminal N that shows continuity to terminal B and mark it to be connected to terminal C. (But DO NOT connect it to terminal C yet.)
Identify the wire that you disconnected from terminal N that shows continuity to terminal C and mark it to be connected to terminal A. (This will be the only one left..) Now connect these three wires to the terminals that you marked them to be connected to. The motor is now wired in delta configuration. Terminal N is no longer used. ADD AN EARTH WIRE TO THE MOTOR.

Les.

martin perman05/05/2015 12:56:11
avatar
2030 forum posts
86 photos

Gentlemen,

I have a Centec 2A which came with sales literature and a typed price list when I bought it a few years ago and the paperwork says 400/440 volts 3/4 hp 1450 rpm other voltage or single phase on request.

The price list quotes 230 volts at £3. 0. 0. extra this was dated July 1948.

The Centec 2 was fitted with a 1/2 hp motor.

My 2A is now fitted with a Machine Mart electric motor fitted to the right side on the outside when looking from the front, this was how I bought it.

Martin P

ash roberts06/05/2015 05:51:32
6 forum posts
3 photos

Great.. thanks Les.. i shall give it a go and let you know how i get on.. many thanks

Edited By ash roberts on 06/05/2015 05:51:47

ash roberts09/05/2015 04:41:28
6 forum posts
3 photos

Do you think i should use a seperate power supply for the table motor & lamp? and a dedicated spindle power supply.

Les Jones 109/05/2015 17:50:05
2244 forum posts
153 photos

Hi Ash,
I do not have the original wiring diagram for your mill so it is difficult to know how to suggest wiring the lamp. There is probably a transformer to feed the lamp which may have the primary tapped at 240 and 415 volts. If this is the case then just use the existing transformer fed with the normal mains connected to the 240 volt tap. (If you have the original schematic can you post it as a picture ?) It would be better to have a separate VFD for the spindle an the table as it would be useful to control the speeds independently. Also most inverters do not like any switching between the output and the motor. (There are some more expensive ones designed to be used with several motors connected to the output with switching of the motors. I suspect one of these would cost more than two of the cheaper types.)

Les.

ash roberts09/05/2015 20:26:50
6 forum posts
3 photos

Hi Less, no wiring diagrams here...

I was going to send a seperate 240v feed to the VFD- table motor and lamp, Bypass the lamp transformer to supply 240v.

The spindle is on a seperate 240v feed via the spindle VFD..

Was just wondering if me trying to conserve plug sockets and only supply all from a junction box off one 240v wall socket was pushing it a bit, or should i just use 2 x 240v sockets.

Edited By ash roberts on 09/05/2015 20:29:26

Les Jones 110/05/2015 09:21:37
2244 forum posts
153 photos

Hi Ash,
If the spindle motor is only 3/4 HP as Martin suggests then there should be no problem feeding both VFDs from the same 13 amp plug. I would suggest mounting both VFDs in the same box (Ensuring suitable ventilation ) You could then use a common EMI filter to feed both VFDs (This is so you can keep the wiring between the EMI filter and VFDs as short as possible. If you need a source of screened power cable to use between the VFDs and motors then Arc Euro Trade sell it by the metre. (It is on this page of their online catalogue.) It is also good practice to use screened cable between the VFDs and the remote controls. This only needs to be signal type screened cable as it only carries very small currents.

Les.

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