Centec 2B Mill buying

[Mark BParticipant @markb43031]

I've been on the lookout for a milling machine for smallish operations (mostly clockmaking) for a while. I've decided that Bridgeport sized machines are too big for my workshop so Tom Senior / Centec sized machines are better for me.

I've been talking to Home and Workshop Machinery about this machine and wondered if anyone had any opinions or advise https://www.homeandworkshop.co.uk/stock-item/centec-2b-/1389/

The price is not far off what I'd spend for a new Chinese machine, but I feel an old and better made machine is the best option.

I've read a few posts on this forum which are generally positive about the Centec machines.

Thanks

[Mark BParticipant @markb43031]

[peak4Participant @peak4]

I have one almost exactly the same and find it does every (reasonable) thing I've asked of it.
Mine also has the swivelling universal table, so make sure you don't need that facility before committing.

It might well be three phase, so do you have a suitable supply?
If it is the same as mine, the main 1HP motor is dual voltage, so easy enough to run off a inverter/VFD, but the table feed motor is 415v only.
I replaced it with a single phase motor, but it's too big and heavy, and does cause a bit of tilt on the table.
I must get around to finding the star point of the old motor, so I can swap it back and run it off a second inverter.
In the short term I help balance it with a universal dividing head bolted to the left hand end, which is useful anyway as it takes a Myford chuck.

The need for two inverters wouldn't be a problem, if I'd gone down the route of a Transwave or similar setup.

Bill

[Frank GorseParticipant @frankgorse]

They are great machines and that one looks to be in fair condition but I would have thought it was on the big side for clockmaking, especially as you say your space is limited.

Also,if you plan to do both horizontal and vertical milling you will soon get fed up with lifting the vh on and off and will be looking for a raising block- see correspondence on this site.

I’ve got a Tom Senior ‘E’ type now which suits me much better and would probably do all you need.

[Mark BParticipant @markb43031]

Thanks for the replies. The machine is 3phase and I've only got a single phase supply in my workshop but I'm happy with setting up VFDs. The table motor as mentioned needs rewiring from star to delta. I found some photographs on this forum from someone who did this already.

Do people think the price of the machine is fair? I appreciate that you will pay a premium from a dealer, but they are able to get it delivered easily which as I live in Scotland is very handy.

[duncan webster 1Participant @duncanwebster1]

Centec with a single phase motor mounted in the cabinet is very noisy. As you intend, get a vfd and keep the 3 phase motor. I'm very happy with mine, but the top speed of the vertical head is a bit slow for little cutters @ 1400 rpm. Even at this speed the head gets quite warm, so I wouldn't be tempted to drive it faster. When you decide you need power feed on the x axis send me a pm.

[Dave HalfordParticipant @davehalford22513]

I think Gary Wooding has a 3000 rpm version. You just need to double all the plated speeds.

The quill vertical head has doubled the price.

The positives are

The gearbox shaft bungs are undamaged so the gearbox has never failed.

The power traverse claims to have the other gear ratios (they should be sitting in the top of the motor.)

Negatives

Where is the horizontal abor and bearing support.

It's outside.

[RobCoxParticipant @robcox]

How about a Centec 2A? There's one for sale on mig-welding.co.uk for 2/3 of the cost of the 2B.

[Dave HalfordParticipant @davehalford22513]

Posted by RobCox on 02/03/2023 19:42:10:

How about a Centec 2A? There's one for sale on mig-welding.co.uk for 2/3 of the cost of the 2B.

If ever there was a classic case of to big a vice that's it.

[peak4Participant @peak4]

Posted by RobCox on 02/03/2023 19:42:10:

How about a Centec 2A? There's one for sale on mig-welding.co.uk for 2/3 of the cost of the 2B.

Also on Facebook Marketplace
https://www.facebook.com/marketplace/item/581167547382965/

Bill

[duncan webster 1Participant @duncanwebster1]

I think 2B has more x travel, lathes.co.uk would know

[not done it yetParticipant @notdoneityet]

Posted by Mark B on 02/03/2023 16:45:05:

Thanks for the replies. The machine is 3phase and I've only got a single phase supply in my workshop but I'm happy with setting up VFDs. The table motor as mentioned needs rewiring from star to delta. I found some photographs on this forum from someone who did this already.

Do people think the price of the machine is fair? I appreciate that you will pay a premium from a dealer, but they are able to get it delivered easily which as I live in Scotland is very handy.

My power feed runs on a 230V VFD, but remains wired in star config. I've never experienced any problem, as yet, with the reduced power. The spindle motor on mine, as a matter of fact, is running with a 220V VFD but is wired Star. But I have taken into account the reduced power output in this configuration for its duty.

I consider the 2B to be a fair improvement over the 2A (the knee operation, table size and headspace. Mine also has a long riser block, so even more height available over the table when vertical milling – and I don’t need to remove the vertical head to go milling horizontally.🙂

The power feed versions lose about an inch of long travel, if that is important and I really appreciate the DRO on mine. Avoids any backlash adjustments when positioning the work.

I find that supplier usually inflates the listed sales price somewhat above reality.

[vic francisParticipant @vicfrancis]

Hi Mark, A good thing is if it comes with the extra head raising block, as they never come up for sale, even eBay.. The coolant tray is massive so getting through a doorway is a problem, and mine was welded on.Its much heavier than I thought!Gary Wooding has a beautiful example, and shows what can be done with this machine with skill and vision.

Vic

[not done it yetParticipant @notdoneityet]

Posted by vic francis on 03/03/2023 00:52:06:

Hi Mark, A good thing is if it comes with the extra head raising block, as they never come up for sale, even eBay.. The coolant tray is massive so getting through a doorway is a problem, and mine was welded on.Its much heavier than I thought!Gary Wooding has a beautiful example, and shows what can be done with this machine with skill and vision.

Vic

I cut my base horizontally, after fitting several brackets across where the cut was to be made. It is now re-assembled exactly as it was originally – less the kerf. Yes it is B. heavy! Mine was slid off the Ifor Williams trailer (like the machine body and base) down an inclined plane.

Bill mentioned a single converter, as opposed to two inverters, but converters are likely rather more expensive than two VFDs. Also no programming, variable speed – and with other cons, to boot!

[Dave HalfordParticipant @davehalford22513]

Posted by not done it yet on 02/03/2023 22:49:29:

I find that supplier usually inflates the listed sales price somewhat above reality.

Centec's are currently a good investment.

Quill V heads have gone from £300 to £1500 in 12 years

Even a Centec 2 has gone up £500 and an 'overarm' is now £160

[Clive SteerParticipant @clivesteer55943]

For a small compact vertical milling machine I purchased a Boxford VM30. It is simple and well constructed with mechanical variable speed head. The only downside is that the hi/lo spindle speed range selector uses an idler gear arrangement that is always engaged for either range so the head is very noisy. My workshop is in the garage which is inside the house so this was a problem. So I grafted a Bridgeport M head on to it and an VFD to reduce the need for belt swapping. The M head has a quill which the VM30 doesn't have which makes drilling more difficult. The more common J head might work but being larger looks out of proportion.

All of this came in for less than £1k.

CS

[Gary WoodingParticipant @garywooding25363]

Cherry Hill, one of the very best, if not the best, model engineers, uses a Centec 2B.

I've fitted VFDs to the the spindle and power feed motors, and added a DRO to mine. It makes for a very nice machine. See my album. One rare thing on mine is that the spindles are ISO30.

[Mark BParticipant @markb43031]

Thanks again for all the replies this is all very helpful. I've decided to go ahead and purchase the machine so I'll report back once I have it and I start to VFDs to bring it alive.

[not done it yetParticipant @notdoneityet]

Posted by Mark B on 04/03/2023 03:42:17:

Thanks again for all the replies this is all very helpful. I've decided to go ahead and purchase the machine so I'll report back once I have it and I start to VFDs to bring it alive.

Mark, you have a PM.

[Mark BParticipant @markb43031]

Well I took delivery of the Centec 2B this afternoon.

On balance I'm pleased with my purchase; it feels like an honest machine so far, but I've yet to power it up. I'm selecting VFDs.

"not done it yet", you mention that you've got the power feed working from a 240V VFD but you've left it in star config. I'm liking the idea of this as I don't relish the thought of picking into the windings to rewire it delta. How did you select a VFD rating for this? The fact that I might lose a little power doesn't worry me as I make small things and make light cuts. Are there any other disadvantages to this approach?

[not done it yetParticipant @notdoneityet]

Mine came, with a single phase main drive and with a tiny VFD already fitted to the power feed. The VFD is a tiny fractional HP device which I’ve never interfered with.

I don’t even change the gear ratio of the power feed since selecting the combination that seems to work OK for me. Highest speed setting is OK-ish for return travel – I’m not usually in a rush – and is less arduous than winding the table back to origin (no half-nuts on my table).

[Mark BParticipant @markb43031]

I had a chat with the people from Inverter Drive Supoermarket who were really helpful and knowledgeable. They pointed me at this article which explains about running 400v motors when you can't change the configuration to delta.

https://inverterdrive.com/howto/240V-Supply-to-a-400V-AC-Motor/

I think this is much safer than picking into the motor windings to rewire it.

[Gary WoodingParticipant @garywooding25363]

I actually burst the star point on my two 3ph motors and added two 2nd hand Mitsubishi VFDs under the suds tray. I have no need to access them, but they are easily visible and out of the way. The major difficulty was the removal of the table motor – see my album. I made a little control box which I mounted on the end of the table – this provides finger-tip control of spindle and table speeds and directions. I would hate to be without it now.

[Mark BParticipant @markb43031]

Thanks for posting the pictures Gary this gives me some good ideas about positioning the inverters and also setting up a remote console too. I've also been looking at your Centec album and like the setup you have for the DRO – I will be doing something similar myself.

The riser block you have on that machine looks very useful – where did you get that from, or was it something you made yourself?

[not done it yetParticipant @notdoneityet]

Posted by Mark B on 18/03/2023 21:36:40:

Thanks for posting the pictures Gary this gives me some good ideas about positioning the inverters and also setting up a remote console too. I've also been looking at your Centec album and like the setup you have for the DRO – I will be doing something similar myself.

The riser block you have on that machine looks very useful – where did you get that from, or was it something you made yourself?

I have one just like that. Most certainly Gary’s was made by himself (he made several) and I expect mine was made by him, too. A very handy piece of kit. The long version saves a lot of manual exertion (which is getting to be too much, for me, these days).🙂

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