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Soba rotary table

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JasonB14/03/2019 10:47:46
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Also need to bear in mind that putting a stepper on it will only solve the 47:1 issue, won't fix any play in the table or compensate for backlash.

Rik Shaw14/03/2019 10:52:34
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I bought a WARCO 6" couple of years ago. Does that make it a SOBA or VERTEX?

Hopper14/03/2019 11:08:25
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Here's the kind of thing I was looking at: LINK

a small 4" dividing head with stepper motor, four jaw chuck and tailstock for $220. A micro step controller costs about an extra $50. Looks like it still uses a worm and wheel though. However, a lot of this stuff on Aliexpress is stuff that is used in Chinese factories for automation and CNC etc and is amazingly good quality, from what I have seen myself. It is not built down to a price for small-volume hobby market but is commercial standard as used in some of the world's most modern factories. So I'm pretty sure the worm wheel is not missing a tooth!

Here's another one: Link

A two-inch chuck on a dividing head with stepper motor with a tailstock. All for $135. No worm on this one. Direct belt drive. Looks a bit flimsy but I'm sure it has big brothers somewhere.

Only a matter of time before this stuff takes over. It's only going to get cheaper too as automation gets into full swing over the next decade. Vis. all those media reports saying half of all jobs will be automated blah blah.

Not sure if any of the model engineering suppliers have picked this ball up and run with it yet? Could be a good little niche market for someone. That first dividing head could easily be turned into a rotary table by flipping it on its side and adding a faceplate instead of chuck. Add a controller and away you go. Nice little package. And supplied as a package ready to use out of the box, even a CNC duffer like me could use one.

 

Edited By Hopper on 14/03/2019 11:20:03

SillyOldDuffer14/03/2019 11:22:39
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Posted by Rik Shaw on 14/03/2019 10:52:34:

I bought a WARCO 6" couple of years ago. Does that make it a SOBA or VERTEX?

Maybe!

The tables are a generic out-of-copyright design. By light engineering standards they're not difficult to make. Anyone could make them almost anywhere in the world. Ketan explained the various sources he's aware of in the trade. They can be had unbranded, or labelled, and at widely different prices.

There seem to be 3 variants on the market. In HV6 size:

  1. Industrial-quality - a few thousand pounds.
  2. Middle-quality - £400 to £800
  3. Hobby-quality - £150-ish

The difference appears to be build quality (materials and finish); I doubt a Bison would be sold with an incorrect gear ratio!

My Warco HV6 is distinctly crude but it works well enough. Chief fault is it sags slightly when the chuck is horizontal. Applying the locking clamps corrects the problem.

Might be fun to buy one of each and compare them. If only I was rolling in money...

Dave

Mike Poole14/03/2019 11:42:22
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Stefan Gotteswinter has a few videos on YouTube of his teardown and improvements he made to his vertex table, much of it would apply to most rotary tables.

I am sure that John Stevenson who did quite a lot of work with converting rotary tables to use a stepper motor made some comments on Vertex lowering the specification over the years on their RT, maybe changing the supplier coincided with the spec changes.

Mike

Edited By Mike Poole on 14/03/2019 11:48:30

Martin of Wick14/03/2019 12:21:14
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I have a Warco/Soba 6" rotary table, Purchased 6 or 7 years ago for around £100 because I only ever buy the cheapest anything on principle, WTF, it is just a hobby.

Perhaps I have been lucky as I can confirm it is perfectly OK for what I do. out of the box it was in a pretty sloppy condition. There are two main adjustments to be made, worm engagement by twiddling the eccentric to give maximum gear engagement while checking for no unacceptable tightening at other points on the rotation and backlash by crimping down the shaft collar to the point where there is an acceptable balance between handle stiffness and minimal lash.

Once adjusted, the backlash is consistent at about 2 minutes of arc at any point on a full rotation, there is a very slight variation in tightness around a rotation, but this doesn't seem to affect angular motion. I manage the backlash by the usual means and can confirm that 90 cranks of the handle returns the table to the starting position give or take a couple of thou. I haven't bothered dismantling it to examine the gearing on the principle of ' if it aint broke, it don't need fixing'.

I have used the table occasionally for milling curves, facets and making a division plate. At the current rate of usage, I have every confidence that the table will outlive me by several centuarys. My only complaint is that it is so heavy, I can hardly lift it, glad I didn't get the 8 inch version.

Ketan Swali14/03/2019 13:05:37
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Posted by Mike Poole on 14/03/2019 11:42:22:

Stefan Gotteswinter has a few videos on YouTube of his teardown and improvements he made to his vertex table, much of it would apply to most rotary tables.

I am sure that John Stevenson who did quite a lot of work with converting rotary tables to use a stepper motor made some comments on Vertex lowering the specification over the years on their RT, maybe changing the supplier coincided with the spec changes.

Mike

Edited By Mike Poole on 14/03/2019 11:48:30

Hi Mike,

I saw Stefan's video. It has 'OPTIMUM' badge on it. I cannot be sure that it is a VERTEX table. Optimum uses Chinese Factory C for some of their supply. Factory C makes the VERTEX copy too. Sometimes, it is possible to copy an instruction manual, for universal use.

If you look at Stefan's video, you cannot see any drawn cup needle roller bearing (NRB) to support the worm assembly, where it enters the casting body. For most light to medium duty RT's this, along with other bearings are omitted. Over the years, the material from which the gear wheel? is made, has also changed. This applies to SIEG RTs from ARC too.

JS used to convert Vertex, ARC, various Chinese and Indian for use with stepper motors. Depending on application, he would check for presence of bearings. to the best of 'my memory' having seen this at Johns place, the old Vertexes had them inside the table, the newer ones didn't. He would strip all of these tables apart, finding good, bad or ugly. he would add bearings if and where necessary, or if a medium to heavier duty application was the purpose of use.

For SIEG RTs from ARC, they are fine for manual use. However, for use in CNC application, we do some modifications, and add some bearings inside the RTs, which makes them better for light to medium use, with much reduced backlash. Although we do not warrant them for business/commercial use, a high percentage of our sales are made to such users..... I guess due to price.

Coming back to VERTEX, I mentioned on page 2 of this thread, that they used to buy from FACTORY A in the past. FACTORY A has clarified to me that they did not buy this product from them. So I was wrong in making that statement, for which I apologise. That guessing goes on.

Thaiguzi mentioned that his VERTEX is around 25 years old - Made in Taiwan. May be it was - totally, or it was finished in Taiwan. I am now getting more and more confused about its origin. Now, all I can say is that VERTEX of old is different from VERTEX of new. In either case, the product does have some consistency in production, and most of the users are well happy with it.... be they with or without bearings.

Chinese Factory B offers the VERTEX copy - with or without bearings. So now I wonder if original VERTEX offered these with and without bearings in the old days or now. indecision. Its all clear as mud.

Ketan at ARC

Ron Laden14/03/2019 13:50:31
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Thats something I forgot to mention, despite its faults my £56 cheapie has the table bearing mounted so maybe its not all bad for the money..smiley

It did surprise me in Stefan,s video to see his Vertex had no bearings, he didnt sound too impressed with that either. I guess they dont need to be though if decent accuracy is achieved using plain bearings.

mgnbuk14/03/2019 14:11:36
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Here's the kind of thing I was looking at: LINK

That looks like an industrial reduction gearbox with a short spindle added. Only 20:1 reduction & no clamping facility. As is typically the case the stepper motors are defined by frame size & current, not rated torque, but by the motor fame sizes output torque isn't going to be great. "This Old Tony" did a welding positioner based on a similar gearbox.

Output torque will be higher than the other item, though - 4:1 reduction with a 52 Ncm motor ! Maybe fine for engraving small plastic or wooden parts (as shown in the "application" photo), but not much more ?

My 6" Vertex RT came from a Harrogate show (Chronos IIRC) at least 15 years ago. Can't say I have noticed anything untoward about, but it hasn't seen much use. I have had mixed experiences with Soba tooling (more bad than good), to the point that I avoid the brand now.

Nigel B

Neil Lawton14/03/2019 17:10:49
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Many good points raised, thanks.
The Soba table I have has the spindle mounted using a needle roller bearing rather than a slide fit. It doesn't feel particularly tight so I don't know how this will cope with machining stresses.

Apart from the issue of accuracy, I would think the lateral movement of the table would allow more of the machining forces to be felt by the worm and gear wheel possibly causing premature failure. I don't know if the Vertex has the same amount of movement, though one of the YouTube videos shows the owner trying to improve the slide fit of his Vertex.

I managed to remove some of the worm gear wheel offset by remounting it. Having to account for variable backlash that was dependent on the angle of rotation was going to be a task beyond my little grey cells.

Since the intended use is just for hobby purposes rather than high precision the advice that I should just get on and use it sounds about right.

I think the main thing to take away is that rotary tables at this price point are not going to take any abuse and need to be used carefully ... just how carefully only time will tell.

The seller has kindly offered a return of goods if I am not happy but the hassle of returning it plus the risk of getting a similar one back makes me reluctant to do that. If it breaks or is unuseable for what I want then lesson learnt and move on. However I would have been prepared to spend more money on a more robust table given what I know now. But is it possible to guarantee that paying more will actually get better quality, especially if suppliers are getting stuff from the same pool of manufacturers. Who is doing the checking that the quality is good and consistent: manufacturer/supplier/seller/user. It all feels a bit hit and miss.

Michael Gilligan14/03/2019 17:45:32
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Posted by Neil Lawton on 14/03/2019 17:10:49:

Who is doing the checking that the quality is good and consistent: manufacturer/supplier/seller/user. It all feels a bit hit and miss.

.

I think that sums it up pretty well, Neil

Unfortunately ... at the hobbyists' price point, I think it most likely that the user provides the quality check.

The better suppliers will, or course, refund/replace a demonstrably bad item ... but the onus seems to be on the end-user to do the checking.

MichaelG.

SillyOldDuffer14/03/2019 18:33:25
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Quite fun to do a cost estimate on a rotary table of the cheaper sort, sold in the UK for about £150. It's easy to show they have to be made for about £40 and the manufacturer doesn't make much profit from it.

Sold in UK for £150

VAT = £37.50, leaving £112.50
UK Seller Profit and Overheads, say 30% = £33.75, leaving £78.75
UK Delivery to Customer = £5.00, leaving £73.75
International Delivery from Factory = £10, leaving £63.75
Manufacturers Profit, say 10% = £6.38, leaving £57.38
Materials, say £15 = £42.38

So guys on the factory floor have to earn their wages (which are taxed), and pay for the cost of energy consumed, and the cost of the factory buildings, and the cost of any loans taken out on machines, and the cost of rejects by turning the raw materials into a finished item in its packaging for about £40. Doesn't leave much room for extras...

Dave

Chris Trice14/03/2019 18:47:53
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Posted by mgnbuk on 14/03/2019 14:11:36:

I have had mixed experiences with Soba tooling (more bad than good), to the point that I avoid the brand now.

Nigel B

Glad I'm not the only one although stating it can get you vilified.

Chris Trice14/03/2019 18:51:48
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Posted by Michael Gilligan on 14/03/2019 17:45:32:
Posted by Neil Lawton on 14/03/2019 17:10:49:

Who is doing the checking that the quality is good and consistent: manufacturer/supplier/seller/user. It all feels a bit hit and miss.

.

I think that sums it up pretty well, Neil

Unfortunately ... at the hobbyists' price point, I think it most likely that the user provides the quality check.

The better suppliers will, or course, refund/replace a demonstrably bad item ... but the onus seems to be on the end-user to do the checking.

MichaelG.

That is what annoys me the most too. I simply don't want to buy something based on pot luck and the continual aggravation of sending stuff back and forth until you get a good one.

JasonB14/03/2019 19:04:54
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Posted by Neil Lawton on 14/03/2019 17:10:49:

However I would have been prepared to spend more money on a more robust table given what I know now. But is it possible to guarantee that paying more will actually get better quality, especially if suppliers are getting stuff from the same pool of manufacturers. Who is doing the checking that the quality is good and consistent: manufacturer/supplier/seller/user. It all feels a bit hit and miss.

Although there may be no guarantee you may get some comeback, for example vertex spec in regards to flatness, squareness and ecentricity can be found on the net so if it is not upto that you may have a case.

As for cost it is hard to tell you may get more for your money or the supplier may just be making more. However as I said early on until your first post I had no reason to take a measurement of how much the table moved, but I did go and measuer mine soon after reading it. My Soba about 8yrs old measures 0.02mm movement with a good hard shove. I also have a 150mm ARC one here that is quite a bit more expensive and I can only get about 1/3rd of a division on the DTI trying as hard as I can so that's 0.003mm or a gnats over 0.0001" or a tenth of a thou. smiley

Edited By JasonB on 14/03/2019 19:10:40

Ron Laden14/03/2019 20:05:13
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You cant complain with those figures Jason, a tenth of a thou on the 6" ARC, thats just excellent. Also less than a thou on the Soba, I can see why you have never noticed any problems in 8 years.

SillyOldDuffer14/03/2019 20:10:42
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Posted by Chris Trice on 14/03/2019 18:51:48:
Posted by Michael Gilligan on 14/03/2019 17:45:32:
Posted by Neil Lawton on 14/03/2019 17:10:49:

...

...

That is what annoys me the most too. I simply don't want to buy something based on pot luck and the continual aggravation of sending stuff back and forth until you get a good one.

In that case Chris, why don't you go up-market?

Special offer today at Chester:

rt.jpg

And if that's not good enough, how about Cutwel's? (Only £3872.24!)

bison.jpg

Just for laughs the VAT on the Bison is £645.37. That's very nearly enough to get you a £499 Chester and a £150 Warco...

I'm not sure there's much mileage in complaining about inexpensive tools - they are what they are. And no-one has to buy them.

How about complaining about the opposite case: why should hobbyists have to pay £3872.24 just to get a decent rotary table? It's a scandal!

devil

Dave

Michael Gilligan14/03/2019 20:26:30
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Have you managed to find one with a calibration certificate yet, Dave

... or must we take all the specifications on trussed trust ?

MichaelG.

JasonB14/03/2019 20:37:04
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Michael, Neil and myself regularly delete first posts from people offering all sorts of certificates, next time I'll pass on their details to you and I'm sure they could sort out whatever documentation you or Dave wantdevil

Michael Gilligan14/03/2019 20:39:59
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smiley

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