Dismantling Vertex HV6 Rotary Table

Hello. I have just bought a Vertex HV6 and attempted to strip it down for cleaning and lubricating. I got everything disassembled except for the worm/eccentric assembly, which I couldn't remove from the main casting. It looks as if the whole assembly is meant to slide out from the casting, allowing the worm and shaft to be withdrawn from the eccentric, but something is stopping this from happening - there is about 2mm to-and-fro movement, but it just stops dead after that. If anyone else has been down this route and can shed light I'd be very grateful. Unfortunately the 'manual' which came with the device is next to useless - the exploded diagram they give doesn't correspond to the machine I have.

Regards, Bob.

Bob,

Its been a while since I stripped mine down but recall similar trouble. Have you removed the set screw from the side of the casting and the thumb screw from the top,these have to be fully removed before you can get the worm assembly out.

Hello Bob,

It is a while since I dismantled mine, Coalburner is correct, there is a small hexagon grub screw in the side that is easily overlooked. After that is free the whole eccentric assemply can be pulled out.

Photo attached

Brian

Brilliant, thanks chaps, I had indeed overlooked the grub screw set deep into the casting at the side. Thanks also for the photo Brian - it looks like your table is rather more refined than mine in that it has needle roller and thrust bearings. Mine has a plain bearing rather than rollers, and no thrust bearings. During my researches I came across a remark somewhere by John Stevenson, dating from 2008 IIRC, that Vertex quality had declined 'by design' - presumably your table predates that decline.

Regards, Bob.

Hello Robin,

My table is badged Myford.

I bought it about 10 years ago at the Harrogate Exhibition to take advantage of a decent show discount. Generally it is nice quality, but even with that provenance there were some minor niggles purely down to building to a price.

Regards Brian

Hi Bob,

I was thinking about buying one of these myself so would be very interested to know what you think of it.

regards

Geoff~

Hi Geoff, first impression was 'ok for the money', ie not as bad as I'd feared, but not so good as I'd hoped. The only measurement I've made so far is with a clock on the MT, which looks OK to better than +/-0.008mm, but that's on the bench so there may be wobble from me cranking the handle etc. It's in bits again now that I know about the secret grub screw, and unfortunately my wife has chosen this crucial time to take to her bed poorly, so I'm in my Florence Nightingale togs at the mo - I'll post in more detail when I've put the table back together and got it bolted to the mill.

Regards, Bob.

got it wrong!

Edited By old Al on 06/01/2014 19:19:38

Hello.

I also bought a Vertex HV 6 around ten years ago from Chronos i think, at Harrogte. Mine is also one fitted with a needle roller radial bearing and thrust bearing, a very nice bit of kit.

I didn't use it much, but when I dismantled it a few years ago I found the factory applied grease had turned solid and jammed the German made radial roller bearing, causing its outer race to rotate in the iron housing of the base casting when the table was rotated. I bought a new bearing which was easy to find.

They are a well made table, but I find if I lubricate the gears with oil it just leaks out between the eccentric worm shaft sleeve and its bore in the base casting due to a bit too much clearance.

Chester Machine Tools used to offer their own brand of rotary table and dividing head which I think we're called Homge. These were externally just about the same as the Vertex items but were claimed to retain the needle roller bearings inside. I am not sure if these are still available.

Edited By Lathejack on 06/01/2014 19:21:36

Edited By Lathejack on 06/01/2014 19:25:51

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Edited By Michael Gilligan on 06/01/2014 23:30:54

Having done quite a few rotary table conversions I can say that in the last 2 - 3 years I have not come across one that has bearings fitted to the worm.

I recently converted a series of ten 10" Vertex tables for a local university and had to source these from 3 different suppliers as no one had 10 in stock. Whilst I would not say they were badly made they had certainly pared the build quality down.

The table sat on flat metal to metal faces and relied on a standard sealed deep groove bearing and no thrusts.

The steel worm ran in a steel eccentric and had a thrust race on the inner side as thrust was only taken in one direction. On the 8" and 10" vertex there is no room to put the worm on bearings, even needle rollers.

[dit] anyone got a spar E key for a HP laptop kyboard ?

Homge was the last small table maker to use bearings but current models don't.

Edited By John Stevenson on 06/01/2014 23:52:34

The thrust bearing referred to is the one that sits on the underside of the table axis to stop it lifting, which can be seen in Brian Wood's photo, and not the worm shaft which just has a plain shoulder.

Jack,

That's the 6", I'm sure current 8" and 10" tables have one thrust on the worm.

One problem is that Vertex is a badge name and they source from wherever thy can, fortunately usually Taiwan but it wouldn't surprise me if China didn't get into the act.

John.

I just thought for a moment that you thought I was referring to needle roller thrust bearings on the worm shaft of the HV6, it is a shame there aren't any.

I have been considering buying a new eight inch horizontal only rotary table, but they don't seem to be available from the usual suppliers, only H/V tables. Amadeal did list one a couple of years ago, but not any more, it looked a bit like the ones that used to be badged Criterion.

Had a time to play with the new table a bit now, so will venture some observations in reply to Geoff's request for an opinion. Caveat lector - I haven't used an RT before, and I'm no engineer,.

Measurements seem to check out OK. There is some runout in the Morse taper, which I estimate at about 0.015mm, and the table surface is parallel to the base to better than 0.01mm. I measured the latter by mounting a clock in the mill spindle, zeroing the clock and the quill DRO, raising the quill, rotating the RT bodily, lowering the quill back to zero then measuring off the clock. Rotating the table under the clock with everthing else stationary gives a flutter of perhaps 0.005mm, but I'm not sure what that proves, if anything.

When I first took it to pieces, all the fasteners were done up with near Allen-key breaking force. As a result there is some quite deep scarring where setting screws bear on shafts etc. Minor niggle I suppose.

There are no thrust or radial bearings anywhere - everything is metal-to-metal. The worm screw is retained in the body of the eccentric by a shoulder at the 'far' end, and by a collar theaded onto the worm shaft at the handle end. This collar incidentally is locked onto the shaft by two grubscrews which bear directly on the thread, which was consequently a bit mangled. Backlash is adjusted by tightening the collar onto a 'wave' type spring washer which bears on the front of the eccentric. This means that if you turn the handwheel clockwise, as recommended in the manual, the spring is in compression. I can't see how this is meant to work - maybe the manual is just wrong.

With the worm fully engaged the table rotates freely for about three quarters of a revolution, then binds somewhat for the remainder. I gather this is par for the course with these tables. However, although partially disengaging the worm helps (with the penalty of more backlash of course), even with the worm almost wholly disengaged it's still there. I don't understand that yet - any elucidation would be appreciated!

The table locks work well - there is no movement of the table on tightening them.

Overall I'm not delighted with this thing, but it's OK for the money and will do what I want after a bit of tweaking.

Dunno if that is any help in making your decision Geoff, but best I can do for now.

Regards, Bob.

Bob,

Try unbolting the gear from the bottom of the table and mover round one hole, then retry, keep going and try all 6 positions to see if the tight spot is better in certain hole positions.

To prevent marring the shafts put a thin slug of brass or copper between the screw and shaft / thread. Normally they do have these fitted.

Bob,

Many thanks for that report - it really is appreciated.

Geoff~

Wow, that was quick! Thanks John, I'll try your suggestion for the gear. Bizarrely the only place they'd put a brass slug was on the screw which locks the graduated collar - which is perhaps the last place that needs it.

Bob.

Robin,

I'm still following this saga with some interest. I think the clearance between the worm and it's gear by having them partially dis-engaged should provide more than sufficient clearance to rule out binding from that source, unless the misalignment is gross.

What is the case when they are fully disengaged; do you still have a tight spot then? If so that will be down to the bearing surfaces at the spigot end of the table.

If you can properly establish that the gear and table fit is to blame as John says above, selective assembly might be the answer. I would though take the gear off and mount it, gripping the gear end in a lathe chuck, suitablly protected with masking tape or similar, and look for wobble on the mounting face. That you could correct with a light skim. Check the corresponding mating face under the table try clocking it off your mill, rotating the table in a vee made up of two clamp blocks on the mill table surface. Correcting that will test your ingenuity but orbital milling comes to mind. You could also check the spigot for true running at the same time.

If you pursue John's plan and find a null point, mark it with centre dots to assist the memory on any future strip down! I was clearly lucky with my purchase, other things I have put right but those fundementals were good at the start..

Brian

Edited By Brian Wood on 09/01/2014 09:29:23

There will always be some play / backlash at some point.

Long , short is, even at £150 these are cheap units mass produced for a general market. With care you can make them better.

You can also buy units with backlash guaranteed to 4 decimal places. I have a Nickon <sp> unit here as a 4th axis on the CNC that is such a unit. Only problem is it's big, weighs as much as an X3, needs a crane to lift it and had a price tag of £7,000 when new.