Centec 2B Mill

[jason evansParticipant @jasonevans10206]

Thanks gary, all good info. It will be in several pieces for the journey home so i m going to go all out and strip/renovate it, and get it how i want it from the off.

[Philip DParticipant @philipd]

With regards the Table motor, I recently got a Elliott Omnimill and paid a local motor rewinders to pull the star point. The cost per motor was £60 this including replacing the bearings, pulling the star point out and a re-varnish.

So I am not sure were you are located but this maybe a viable option, thus enabling you to run on inverters as planed.

[jason evansParticipant @jasonevans10206]

Thanks philip, definately an option. Im swaying towards getting a new dual voltage motor which has forward/reverse option. Could anyone who has done this recommend a suitable motor.

Thanks

Jay

[Philip DParticipant @philipd]

Hi Jay,

The motor that is on the machine now will forward and reverse it just needs suitable wiring. If you weren't using an inverter you would just have to wire it through a suitable switch, but the inverter will control speed as well as forward an reverse.

Edited By Philip Devonport on 15/01/2017 20:38:39

[jason evansParticipant @jasonevans10206]

Ah got it phil cheers. Im in north kent so will have a look for local motor rewinders.

[jason evansParticipant @jasonevans10206]

hi guys

the vertical head is missing its drawbar, could anyone please help with pics/ dimensions of theirs.

thanks

jay

[Gary WoodingParticipant @garywooding25363]

Here's mine

[jason evansParticipant @jasonevans10206]

superb gary, exactly what I'm after. many thanks

jay

[duncan webster 1Participant @duncanwebster1]

Mine's 3/8" BSW. Most 2 morse tooling has 3/8"BSW or M10. There has been correspondence here or somewhere else about it being impossible to get M10 down the central hole, so I'd just check if I were you

[Another JohnSParticipant @anotherjohns]

Just checked – I have *five* drawbars for my 2B. Two of them are M10, differing lengths, some came with the mill, some were made by yours truly.

Different M2 tooling will have different requirements, as will the lengths for the horizontal and vertical spindle.

The ER25 holder (M10 thread) has been in the vertical head for about 5 years; I do have some small drill chucks on stub (straight) 1/2" shafts that do fit in the ER25 collets, so there's no need to take the ER25 collet holder off the machine.

The M10 drawbars were made with M10 threaded rod ends, drilled, (possibly loctited) and certainly pinned on to some round steel shafting, with another bit of steel hex (1/2"??) at the top – drilled, (loctited?) and pinned. There are washers under the steel hex.

I've made drawbars for my CNC milling machines, same method, except one of the mills, I used a hex head cap screw loctited in place for the top, as getting a spanner on it would have been difficult.

I'm sure the purists would scowl at the methods, but, no issues, and making them simply/quickly allows more time for model building… (so I should log off and get to the workshop!)

Regards – another JohnS.

[jason evansParticipant @jasonevans10206]

Thanks again to all.

Sorry for the possibly dim question but regarding 220v vfd's, what power would be sufficient for a 1hp motor.

Jay

[BikepeteParticipant @bikepete]

Posted by jason evans on 21/01/2017 14:43:24:

…regarding 220v vfd's, what power would be sufficient for a 1hp motor

1 HP, also known as 0.75 kW. Almost always you just need a VFD with the same power rating as the motor.

[not done it yetParticipant @notdoneityet]

The more usual advice is to get one a little larger than the motor rating. Cannot go too far in excess or the operating parameters may not extend low enough, but remember some motors are specced as 0.75 kW out and some VFDs may be specced as 0.75kW power handling – so be careful! An inefficient motor might be stretching th

e VFD!

The 1/2 HP 415V VFD on my lathe sometimes gives up if I accelerate my lathe too abruptly.

[jason evansParticipant @jasonevans10206]

Ok cheers.

Has anyone replaced the table feed motor. If so what make model did they swap it with.

Thanks

Jay

[peak4Participant @peak4]

Posted by jason evans on 24/01/2017 20:48:23:

Ok cheers.

Has anyone replaced the table feed motor. If so what make model did they swap it with.

Thanks

Jay

Yes I did when I first got it, but I was a bit hampered at the time due to having my leg in a pot, so transport options for the replacement were limited.

I struggled to find a small enough one from local suppliers, so had to make do with a 1/4 HP single phase one, which is in a large frame size. It fits OK, but needed the output shaft machining down to duplicate the 3 phase one already fitted.

From my experience, I'd try and find a smaller lighter motor than I did, as the extra weight hanging off one end of the table does cause accuracy issues. If I remember tomorrow I'll see if I can arrange a photo of some sort to illustrate the problem.

Good Luck

Bill

[jason evansParticipant @jasonevans10206]

Posted by peak4 on 24/01/2017 20:59:59:

Posted by jason evans on 24/01/2017 20:48:23:

Ok cheers.

Has anyone replaced the table feed motor. If so what make model did they swap it with.

Thanks

Jay

Yes I did when I first got it, but I was a bit hampered at the time due to having my leg in a pot, so transport options for the replacement were limited.

I struggled to find a small enough one from local suppliers, so had to make do with a 1/4 HP single phase one, which is in a large frame size. It fits OK, but needed the output shaft machining down to duplicate the 3 phase one already fitted.

From my experience, I'd try and find a smaller lighter motor than I did, as the extra weight hanging off one end of the table does cause accuracy issues. If I remember tomorrow I'll see if I can arrange a photo of some sort to illustrate the problem.

Good Luck

Bill

Ok bill cheers, anymore info/pics would be much appreciated

Atb

Jay

[jason evansParticipant @jasonevans10206]

hi all

my table motor is dead so I'm looking for a replacement. can anyone help in finding one.

have searched the web but can not find any info on make/model that will fit.

atb

jay

[peak4Participant @peak4]

Jason, any idea why it's died?

It may end up being easier to get it mended, with it wired as star, and get a suitable inverter to drive it.

Whereabouts in the country are you?

Bill

[jason evansParticipant @jasonevans10206]

Hi bill

Admittedly I jumped in to it trying to change it from star to delta, but it just wont

Run at all now. I'm in north Kent.

Atb

Jay

[peak4Participant @peak4]

Sorry, too far from me in Buxton/Sheffield.

Are you sure you have all the windings the correct way round?

Lets call the old connections A,B,C, and their relevant star points As, Bs, & Cs.

I believe the delta connections should be;

As-B, Bs-C, Cs-A with the inverter supplying those connection points.

I've not yet done this myself, but have brought my motor up here to do the job.

[jason evansParticipant @jasonevans10206]

Thanks bill.

Ok im going to look at it again. Would someone be kind enough to post a pic of how they have wired an inverter to their table motor. I have one wired for the main motor but cant get my head around the table motor.

Thanks

Jay

[Hugh AllenParticipant @hughallen31308]

Hello. I am restoring a Centec 2b and things are going well, now that I've been able to lay my hands on a Mk III head. The main issue is the x-axis lead screw and half nut, both of which have seen better days. Can anyone advise me if there is any company that makes a copy of the 5/8" x-axis screw and does anyone know of a source for the acme half-nut? Or if conversion to a full nut is more practical? Seems that the half nut is only to allow for quick reverse traverse, which isn't that much of a priority.

[not done it yetParticipant @notdoneityet]

Posted by not done it yet on 11/01/2017 18:06:30:

 

The half nuts, I believe, can be done away with, if they fail and cannot be sourced/repaired, and a full manual lead screw nut installed. Those half nuts are only to allow for fast traverse of the long travel and, as hobbyists, we are not usually in that much of a hurry….?

My post from page one.

Mine has part of the fast traverse (bits fitted at manufacture) but it is fitted with a full lead screw nut at the power feed end of the slideway. I expect quite a lot have been modified thus, over the years. I’m sure a lead screw can be machined from a suitable length of bought-in threaded rod. No need to be ACME if the nut is changed. I’m sure some purists would cringe, but if still manufacturing, Centec would be supplying metric bits by now!  

Might need a different scale on the manual handle, or just fit a dro and not bother with the scale (I don’t use the scale, only count the turns for a 1”, or multiple, movement, if working on something in imperial measurements.

Edited By not done it yet on 19/01/2018 20:01:27

[not done it yetParticipant @notdoneityet]

Deleted.  Double post

Edited By not done it yet on 19/01/2018 19:55:05

[Hugh AllenParticipant @hughallen31308]

Just thought I'd make a post about spares for Centecs. I was looking for a lead screw and half nuts for my (now refurbished) 2b, and had more or less given up but then came across a small but excellent shop in Solingen, Germany (where I live) It is a company that specialises in repairing and maintaining a lot of old British equipment in the Wilkinson factory here in Germany. They made for me excellent quality x and y lead screws and nuts – including the half nut, machined out of solid phosphor bronze stock. The machine can be see on lathes.co.uk under the Centec page (the green 2B machine. This has a good pic of the half nut we made.). As a result I've started offering a service for making half nuts for 2As and 2Bs and have now shipped off two half-nuts for early 2As. The lead screws are all stainless acme threads, but we don't use Woodfruff keys but standard milled keyways. I'd be happy to supply anyone who is interested. By German standards the half nuts are cheap (seeing as how they are solid stock) at €250 – and I do this as a service, but don't take any commission. Lead screws much the same depending on whether or not it's for the 2b €250, or the 2A (€200). If anyone's interested then contact me at hugh@vsla.net of call my home on +49 212 818305. I can send you a full set of photos. The company also refurbishes the gears in the 2B gearbox. I'm having that done right now but will post on the results in a few weeks.

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