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Centec 2B - New arrival and Q&A

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not done it yet03/08/2021 14:20:18
6279 forum posts
20 photos

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).

Andrew Johnston03/08/2021 14:31:05
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6235 forum posts
676 photos
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 Ayerst03/08/2021 16:57:42
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259 forum posts

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 3x3" 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 yet03/08/2021 18:10:17
6279 forum posts
20 photos
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 3x3" 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 Halford03/08/2021 18:12:20
1671 forum posts
19 photos
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 3x3" 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 Design03/08/2021 18:37:12
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144 forum posts
239 photos

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 Ayerst04/08/2021 08:50:07
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259 forum posts

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 Halford04/08/2021 10:51:21
1671 forum posts
19 photos

Same noise on horizontal only?

Every gear?

not done it yet04/08/2021 11:05:49
6279 forum posts
20 photos

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 Halford04/08/2021 11:17:11
1671 forum posts
19 photos

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 Ayerst05/08/2021 09:24:45
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259 forum posts

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 Halford05/08/2021 10:47:36
1671 forum posts
19 photos

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 Ayerst05/08/2021 11:15:33
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259 forum posts

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 yet05/08/2021 11:35:35
6279 forum posts
20 photos

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

Dave Halford05/08/2021 12:26:15
1671 forum posts
19 photos

That noise may even be a crack working already as the motor wobbles it sounds a bit like metal scraping past metal. Cutting the hole for the motor has weakened the cabinet backplate so much it needs some extra top to bottom bracing anyway.

Check the pulley ,then the shaft, the previous owner has done something he shouldn't.

William Ayerst05/08/2021 16:05:38
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259 forum posts

No cracks, got the motor out and gave it a run with and without power - there's a faint scratching as it rotates - I'm not sure if this is the same as the rhythmic sound it gives out when the belt is connected - it seems to be once per revolution and I think that'd probably come out as a shriek or whirr at normal RPM?

Either way, here's the video:

https://www.youtube.com/watch?v=X8XryY7FD7Q

I've not the faintest on how I might go about doing anything about this, is it best left to a specialist or is there something obvious I can check?

The motor baseplate was 'skewed' on the L-brackets with relation to the axis of the motor and pulleys.

Edited By William Ayerst on 05/08/2021 16:11:13

William Ayerst05/08/2021 16:40:24
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259 forum posts

An example of the original knocking/tapping sound with the mill in use is in this video - timestamp from 0:23

https://youtu.be/IcNPDVK5wHY?t=23

Dave Halford05/08/2021 16:48:47
1671 forum posts
19 photos

The pulley wobbles Will, and it sounds like a shot bearing as well.

You need to get that pulley off and see if the shaft wobbles. If it does it still may just be the bearing

The scraping sound might be the armature touching inside if the bearing is really bad.

Or you just buy a new motor, a 'specialist' will cost you 3 times what a a new motor will.

Edited By Dave Halford on 05/08/2021 16:51:32

William Ayerst05/08/2021 17:44:17
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259 forum posts

OK! One step at a time, then!

I guess a gear puller to get the pulley off? Something like these? https://www.amazon.co.uk/Puller-Bearing-Removal-Internal-External/dp/B01CIEUXQQ/ ?

Dave Halford05/08/2021 18:06:02
1671 forum posts
19 photos

Undo the grubscrew it may not be on very tight. Or rather it should not be a tight fit.

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