Centec 2B – New arrival and Q&A

[Dave HalfordParticipant @davehalford22513]

Posted by William Ayerst on 02/08/2021 09:18:03:

Realistically I think I may have just fallen foul of expecting 1/4" square rod to actually be 0.250" .

All the best!

New millers first mistake, not measuring the stock

2nd mistake not remembering that different to a lathe bright steel unlike black can be full of stresses and a freshly milled surface can turn into a banana after a decent cut if not balanced by a similar cut on the opposing side.

[peak4Participant @peak4]

William, Re the chrome dome nut leaking. it doesn't seem to do much other than retaining the stop pin behind it; mine leaked too, so I added either a fibre or a copper washer underneath it.
Re lubrication, none of the documentation I've managed to find specifies what to use in the V head, so I'm just using the same as the main gearbox i.e. Shell Vitrea 41 equivalent. essentially a plain ISO 100 oil
See Tony's site
http://www.lathes.co.uk/faq/page19.html

Yes you're correct, the ¼" stock probably isn't either ¼" or square.

For the most part, I've not found much difference in use between the ball ended or cylindrical edge finders, so I just use the 0.2" one, as it's a simple one turn of the graduated handle to allow for ½ the diameter to show the edge. (It would be a pain using a metric one on an imperial machine, or vice versa.)
It is worth wiping a stone over the stock material before using an edge finder, to remove any burrs, which might mislead.

Bill

 

Edited By peak4 on 02/08/2021 12:24:07

[not done it yetParticipant @notdoneityet]

Posted by William Ayerst on 02/08/2021 09:18:03:

Peak4/Bill, I'm using the wiggler with a 1/4" ball head. Are these cylindrical finders better? In the meantime, should I be paying attention to it stop oscillating as my zero, or when it deflects?

Realistically I think I may have just fallen foul of expecting 1/4" square rod to actually be 0.250" .

I managed to nip up the bolt on the front of the vert head, it just seemed to be leaking oil through the loose bolt hole without it. Any ideas on what oil should go in it?

All the best!

Any edge finder can be perfectly still (not oscillating) at any time – whether touching or in free air. A wiggler should be stationary when touching a tiny spotted mark but a cylindrical edge finder must have gone just beyond the non-oscillating stage to be sure of the correct point. Clearly no (well minimum) error at all if finding both edges (of a parallel part) to determine the centre between those two sides.

Setting your origin (zero, zero) to a selected square corner of a part should work for most instances. DROs are far superior than making backlash adjustments🙂 .

[Gary WoodingParticipant @garywooding25363]

Posted by peak4 on 02/08/2021 12:23:54:

William, Re the chrome dome nut leaking. it doesn't seem to do much other than retaining the stop pin behind it; mine leaked too, so I added either a fibre or a copper washer underneath it.

Edited By peak4 on 02/08/2021 12:24:07

I would think that you've overfilled the quill if there's a leak around the dome nut. The quill is the oil reservoir, or have I miss-understood it or all these years? .

[Nigel McBurney 1Participant @nigelmcburney1]

For a good finish on brass,use a flycutter .

[Richard MillingtonParticipant @richardmillington63972]

Posted by Gary Wooding on 02/08/2021 07:19:07:

Posted by Richard Millington on 01/08/2021 20:19:40:

"What is the purpose of the nut on the front of the vertical head? It seems to just spin in place on my one."

It limits the vertical movement of the quill, otherwise it would hit the oil level dipstick which does.

2BA grub screws for the gib adjustment on the 2A, as above 1/4 BSF thread for the locks. All the threads on my 2A are either BA or BSF, I assume they would not change for the 2B.

For the Mk3 VH there is a small grub screw, just behind the quill lock handle, that pokes into a slot that limits the quill vertical movement. The nut on the front of the VH does nothing on my VH.

The boss attached to the front nut on mine stops the vertical movement of the quill before the grub screw (dog point on mine) gets to the bottom of the milled alignment groove. About 1mm clearance to the bottom of the groove, maybe someone has re-worked it during its' life, but the quill and casting base line up (at the moment anyway as I am going to put a DRO on that ).

[not done it yetParticipant @notdoneityet]

Posted by Nigel McBurney 1 on 02/08/2021 17:50:35:

For a good finish on brass,use a flycutter .

I’ve not milled brass with my Centec. I would likely try horizontal with a slab mill for a very flat surface. No risk of tramming issues and only a single finishing pass for the whole surface. William has no need to remove the VH to change to horizontal, so very easy to swap modes.

[not done it yetParticipant @notdoneityet]

William,

Don’t overlook the horizontal MT option for drilling horizontal holes. Can be useful at times… don’t always need the overhead support for using that drive.

[William AyerstParticipant @williamayerst55662]

I'd not considered a slab cutter but that does make alot of sense. My widest horizontal cutter is 5/8" – other than a 1" bore is there anything I should be considering with regard to teeth/etc. on a cutter like this?

I tried to cut a piece of aluminium flat using a horizontal cutter and ended up with a tiny groove on the outside edge of the cut. I don't know if this was because the overarm was sagging and causing the arbor and cutter to sit at an angle, or something else. The VH was on the front of the overarm/spacer so next time I'll try pushing that back along the dovetail.

That nut on the front of the VH had oil leaking out of it like crazy, so I used an aircraft screwdriver to hold the stud on the inside and tighten it up on the outside.

Turns out the disc on my wiggler is only nominal 0.100" – actually 0.1185" – that would have been annoying! I grabbed a M&W 0.500" edge finder too – not because I think I need it, but more because it will fit in the clarkson chuck and is roughly the same height as a mill – rather than having to crank the table down 3-4" and then back up again!

Edited By William Ayerst on 03/08/2021 08:53:51

[Anonymous]

Posted by William Ayerst on 03/08/2021 08:52:45:

I'd not considered a slab cutter but that does make alot of sense. My widest horizontal cutter is 5/8" – other than a 1" bore is there anything I should be considering with regard to teeth/etc. on a cutter like this?

Do everything up tight, and then tighten some more, and ensure the cutter is well supported. Make sure the work is firmly held; I've had a slab mill lift work out of a Kurt vice. Spindle speed the same as any other cutter of the same diameter. Feeds based on number of teeth and number of thou per tooth. I usually start at 4 thou per tooth. From a practical viewpoint I suspect the lack of arbor keyway and lack of power will be the limiting factors. A slab mill can remove serious amounts of metal; this is pussyfooting as the mill didn't even notice as the cut started:

Andrew

[Dave HalfordParticipant @davehalford22513]

Can't beat Andrew ……………. but I can offer photos of my 2Aminus as it was then (minus a gearbox) with a 2 belt drive facing the top and bottom of it's own raising block.

Note that the nut does not touch the bearing and it's only a 2 thou cut.

[not done it yetParticipant @notdoneityet]

Dave,

No contest between you and Andrew – you (likely) had 3/4HP and Andrew had 3 (or maybe 5)HP!

If I ever have enough spare energy and time, I might make myself a two piece vise (and some way of sharpening my cutters).

[Anonymous]

Posted by not done it yet on 03/08/2021 14:20:18:

………….Andrew had 3 (or maybe 5)HP!

My horizontal is 5hp in the high speed range, 4hp in low speed. That's why I've never made it cough whereas I've stalled the other mills (and lathe) by being over-ambitious.

Andrew

[William AyerstParticipant @williamayerst55662]

Yes, the nut not touching the bearing is something I've realised after cleaning my undies out. It seems homeandworkshopmachinery have a new-old-stock Clarkson 3×3" slab cutter for £54 – is that about the right price for one?

I think I'll need to move the VH back on the riser block so it's ontop of the main column insteead of above the overarm support – my gut feeling is that a bit of

[not done it yetParticipant @notdoneityet]

Posted by William Ayerst on 03/08/2021 16:57:42:

Yes, the nut not touching the bearing is something I've realised after cleaning my undies out. It seems homeandworkshopmachinery have a new-old-stock Clarkson 3×3" slab cutter for £54 – is that about the right price for one?

I think I'll need to move the VH back on the riser block so it's ontop of the main column insteead of above the overarm support – my gut feeling is that a bit of

Don’t know but I would be a little be wary of their ebay pricing. They are currently asking a ridiculous BIN of £250 (delivered) for a fixed steady. Another auction, for both fixed and moving steadies, started at twenty quid (currently forty quid) and doubtful if it goes as far as two hundred.

They have an ‘ebay shop’ so are able to list contact details, so always good to make a sensible offer instead of being a mug (well, the person who buys the steady would be one, at that BIN price). I suspect it is a ploy to avoid selling through the auction site. They would save ebay commission, for a start and might still be over-priced.

I’ve bought job lots of used cutters. Not much money but not all sharp.

Edited By not done it yet on 03/08/2021 18:11:31

[Dave HalfordParticipant @davehalford22513]

Posted by William Ayerst on 03/08/2021 16:57:42:

Yes, the nut not touching the bearing is something I've realised after cleaning my undies out. It seems homeandworkshopmachinery have a new-old-stock Clarkson 3×3" slab cutter for £54 – is that about the right price for one?

I think I'll need to move the VH back on the riser block so it's ontop of the main column insteead of above the overarm support – my gut feeling is that a bit of

One inch are quite rare + it's a big chunk of HSS

[ken king, King DesignParticipant @kenkingkingdesign]

For my Centec I have two drill chucks of differing capacities. The smaller drives via the MT alone with the drawbar just resting on it, whilst the larger 1/2" chuck employs the drawbar. I remove the larger by slackening the drawbar a turn or two, then giving a sharp blow, BUT I always lock the spindle vertical travel first to protect it from the whack. I'd much rather use this axial force method than a wedge or wedges which will inevitably apply asymmetric shock loads to the bottom spindle bearings, quite different to sideways cutter forces.

Enjoy your mill,

Ken

[William AyerstParticipant @williamayerst55662]

Thank you – spoke to H&W Machinery and got a discount on the 3x3x1 slab cutter just for the sake of trying it out.

Another thing I've noticed is just how loud the Centec is while running – there's a definite knocking sound. I've heard if it runs on a single phase motor then it's prone to knocking and there's a tie-bar between the panels already. However, it's got a 3-phase motor with an inverter – so I wonder if it's something else I should be checking?

[Dave HalfordParticipant @davehalford22513]

Same noise on horizontal only?

Every gear?

[not done it yetParticipant @notdoneityet]

As per Dave, really.

Remove drive belt from motor – still noisy, its the motor.

Try with only horizontal belt (to gearbox) fitted. No noise – it must be the vertical head. With noise, it could still be the motor…

Remember to try it with motor running both ways (motor and gearbox are reversed when vertical head is used.

The single phase problem is a vibration or ‘drumming’ sound due to base vibrations, rather than a ‘knocking’ sound.

Check belts for damage, including hard spots on the belt(s). Check all pulleys are tight on their shafts and that end-float is at a minimum.

[Dave HalfordParticipant @davehalford22513]

Lets hope it's the VH belt tensioner bearing, if you have the tensioner wheel on the outside of the belt it might be a lumpy belt. Older Fenner's have the name moulded to stand out.

The gearbox should not be unduly noisy

Edited By Dave Halford on 04/08/2021 11:19:07

[William AyerstParticipant @williamayerst55662]

Righto, I've done some troubleshooting – slowing the mill right down, the sound which was like knocking at high RPM becomes more like a laboured 'whrr' sound at one point in the revolution.

I took some video of the various configurations:

https://www.youtube.com/watch?v=1cv1vCGYMXo

It sounds like it's coming from the motor end of the main belt. It is audible even when the main horizontal spindle is rotated by hand. Without the belt connected the motor is quiet at all speeds.

The previous owner moved the motor mount to outside the base for easier access (and in full disclosure he said that this might need looking at) – it is bolted to the sheet metal outside. While it's not going anywhere, it looks like it's subject to a fair amount of vibration and oscillation. Were that the fault I'd not expect to hear the 'same' noise when turning over by hand. Maybe there is some misalignment or something?

I'm not really sure how to troubleshoot this one!

[Dave HalfordParticipant @davehalford22513]

The motor mount wobbles so bad it will crack the stand in time and you can see the pulley wobbles as you pull the belt by hand, so the motor shaft may be bent or the pulley has been fudged to fit the motor and is off centre.

[William AyerstParticipant @williamayerst55662]

Hmmm! What to do? Presumably take the motor off and see if anything obvious is going on there?

Is it worth putting the motor back inside the chassis? I'm not sure what the original arrangement would have been!

Edited By William Ayerst on 05/08/2021 11:34:57

[not done it yetParticipant @notdoneityet]

The wobbling pulley was the instantly obvious thing I noticed, when turning by hand. The motor alone did not sound as quiet as maybe it should. Might just need a (tiny) bit of lube?

Motor certainly needs to be checked out as the ‘knock’ seems to be motor revolution related. Guessing here that the original pulley has been bored out incorrectly for the 3 phase motor shaft. I could not find a suitable replacement pulley when I changed mine to three phase.

It really needs both belts, to drive consistently without needing to tension the belt(s) so tight. I also feel that the single belt, to the vertical head, would be better changed to twin belts, as well. It has been ‘on my list’ to change that ever since I got my mill.

Edited: Access to the motor inside the cabinet is definitely restricted.  Mine sat on one, or two,  pieces of angle iron with flats welded at each end.  I am dreading fitting the motor when I move it from bench to cabinet.

Edited By not done it yet on 05/08/2021 11:42:52

[Author]

Posts