Soba rotary table

[Michael GilliganParticipant @michaelgilligan61133]

[Mike PooleParticipant @mikepoole82104]

No doubt some metrology lab would calibrate a RT but it might have a severe impact on the hobby budget. Might be a better idea to bin the dial guage and only investigate if problems become apparent.

Mike

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Mike Poole on 14/03/2019 21:37:48:

No doubt some metrology lab would calibrate a RT but it might have a severe impact on the hobby budget.

.

Yes … that's exactly why I mentioned it in the context of Dave's costing analysis.

MichaelG.

[Neil WyattModerator @neilwyatt]

Posted by John Pace on 14/03/2019 09:54:00:

I just wonder how long rotary tables will be made in the conventional way .
Other threads on rotary tables have highlighted the strength problems
with worm and wheels .
This video shows these spiroid and helicron gears which can be made
with zero backlash.
https://www.youtube.com/watch?v=gRriAf5snqs

A photo here of a test gear hobbed using a 1 module cutter ,the worm would
fit in about the 1 o'clock position and have about 5 teeth in mesh at the same
time.
John

Good idea John, a bargain basement (<£5) angle grinder 36-tooth gear might be just the thing for a small rotary table.

[SillyOldDufferModerator @sillyoldduffer]

Posted by Michael Gilligan on 14/03/2019 20:26:30:

Have you managed to find one with a calibration certificate yet, Dave

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

MichaelG.

No sign of any certificates on offer, but the website does give a specification, eg, for the 5859 series:

Due to the three dividing plates, division into the required number of sections is obtained with an accuracy of 1’
Dividing means of graduated drum with 1’30”
Parallelism of clamping surface to base 0,02 mm
Flatness of clamping surface 0,02 mm
True run-out of tapered centre bore 0,01 mm
Squareness of clamping surface to angle face 0,02 mm
Centering Morse taper sleeves are hardened and ground, extending machine life
Possibility of worm wear compensation and worm disconnection from outside of the body
Depending on the size gear ratio is 1:60, 1:90, 1:120
High stiffness

Good rather than spectacular. I'm sure they're excellent, but far too expensive for this hobbyist!

Dave

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Neil Wyatt on 14/03/2019 22:09:51:

Good idea John, a bargain basement (<£5) angle grinder 36-tooth gear might be just the thing for a small rotary table.

.

Agreed … and I think 36 teeth would be considerably more versatile than 47

Only reservation is that angle grinders usually [and intentionally] have loads of backlash … so it might be preferable to make a special pinion.

MichaelG.

[HopperParticipant @hopper]

Posted by Michael Gilligan on 14/03/2019 22:18:50:

Posted by Neil Wyatt on 14/03/2019 22:09:51:

Good idea John, a bargain basement (<£5) angle grinder 36-tooth gear might be just the thing for a small rotary table.

.

Agreed … and I think 36 teeth would be considerably more versatile than 47

Only reservation is that angle grinders usually [and intentionally] have loads of backlash … so it might be preferable to make a special pinion.

MichaelG.

Might just be a matter of how close the pinion is mounted to the crown wheel. Make your own housing with pinion located to minimize backlash.

And if you do a search on Aliexpress for worm gear there are dozens and dozens of worms and gears available for $20 or so, some of which would be ok for a small RT etc. All part of the tsunami of automation components coming on line from over there.

[Chris TriceParticipant @christrice43267]

Posted by SillyOldDuffer on 14/03/2019 20:10:42:

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:

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

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!

Dave

It's not about chasing tenths of thou's. It's about the failure to meet the basics claimed for the product. One would expect a collet chuck designed to fit a Myford spindle would actually be able to be screwed on and not be too small. It's not unreasonable for the customer to expect the product to actually do that simple thing.

[JasonBModerator @jasonb]

Posted by Michael Gilligan on 14/03/2019 22:18:50:

Posted by Neil Wyatt on 14/03/2019 22:09:51:

Good idea John, a bargain basement (<£5) angle grinder 36-tooth gear might be just the thing for a small rotary table.

.

Agreed … and I think 36 teeth would be considerably more versatile than 47

Would that not depend on the mating pinion, seem to recall that grinder gears are actually something like 4.1:1 to even out wear which would result in some rather coarse adjustment and odd angle per turn of the handle.

[Ron LadenParticipant @ronladen17547]

Posted by Chris Trice on 15/03/2019 00:49:57:

Posted by SillyOldDuffer on 14/03/2019 20:10:42:

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:

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

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!

Dave

It's not about chasing tenths of thou's. It's about the failure to meet the basics claimed for the product. One would expect a collet chuck designed to fit a Myford spindle would actually be able to be screwed on and not be too small. It's not unreasonable for the customer to expect the product to actually do that simple thing.

I was quite surprised to read you have a pair of Chinese (Vertex) rotary tables Chris, from a good number of your posts you do tend to give the impression that you wouldnt touch anything Chinese with a barge pole. I assume you must be quite happy with them then..?

[Michael GilliganParticipant @michaelgilligan61133]

Good point, Jason … but

(a) the big gear, used in conjuction with a special worm, remains an interesting possibility

(b) for 'fourth axis' curve-milling [rather than dividing work] the low ratio would probably suffice.

MichaelG.

.

Certainly cheap enough to have a play with:

https://www.ebay.co.uk/itm/Dark-Gray-spiral-set-conical-gear-for-Makita-9523-angle-grinder-S4M4/202572384658

Edited By Michael Gilligan on 15/03/2019 08:08:05

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Ron Laden on 15/03/2019 07:45:34:

I was quite surprised to read you have a pair of Chinese (Vertex) rotary tables Chris, from a good number of your posts you do tend to give the impression that you wouldnt touch anything Chinese with a barge pole. I assume you must be quite happy with them then..?

.

I don't want to speak for Chris, Ron … But I think it's fair to say that the early Vertex tables [made in Taiwan] were produced to an acceptable standard. They were certainly good enough for Myford [Beeston] to sell a version under its own name.

The problem is … those standards appear to have slipped.

MichaelG.

[Ron LadenParticipant @ronladen17547]

Posted by Michael Gilligan on 15/03/2019 08:00:30:

Posted by Ron Laden on 15/03/2019 07:45:34:

I was quite surprised to read you have a pair of Chinese (Vertex) rotary tables Chris, from a good number of your posts you do tend to give the impression that you wouldnt touch anything Chinese with a barge pole. I assume you must be quite happy with them then..?

.

I don't want to speak for Chris, Ron … But I think it's fair to say that the early Vertex tables [made in Taiwan] were produced to an acceptable standard. They were certainly good enough for Myford [Beeston] to sell a version under its own name.

The problem is … those standards appear to have slipped.

MichaelG.

Morning Michael,

I thought the early Vertex were made in China and finished in Taiwan but I could be wrong.

Ron

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Ron Laden on 15/03/2019 08:06:09:

Morning Michael,

I thought the early Vertex were made in China and finished in Taiwan but I could be wrong.

Ron

.

You may be correct, Ron … It doesn't really matter

The expression "made in" is pretty meaningless in real terms.

MichaelG.

[Former MemberParticipant @formermember32069]

[This posting has been removed]

[Chris TriceParticipant @christrice43267]

Posted by Ron Laden on 15/03/2019 07:45:34:

I was quite surprised to read you have a pair of Chinese (Vertex) rotary tables Chris, from a good number of your posts you do tend to give the impression that you wouldnt touch anything Chinese with a barge pole. I assume you must be quite happy with them then..?

I've mentioned earlier on in the thread that the two (older) Vertex rotary tables (and a couple of collet sets) I have I'm very pleased with although ironically all the chat here about changing allegiances to different factories and missing bearings while creditably honest actually weakens my faith in them as a brand. It comes back to my previous point about how is a customer supposed to grow faith in a particular brand and choose them over others if the brand keeps changing their standards?

[Chris TriceParticipant @christrice43267]

Posted by Ron Laden on 15/03/2019 08:06:09:

Posted by Michael Gilligan on 15/03/2019 08:00:30:

Posted by Ron Laden on 15/03/2019 07:45:34:

I was quite surprised to read you have a pair of Chinese (Vertex) rotary tables Chris, from a good number of your posts you do tend to give the impression that you wouldnt touch anything Chinese with a barge pole. I assume you must be quite happy with them then..?

.

I don't want to speak for Chris, Ron … But I think it's fair to say that the early Vertex tables [made in Taiwan] were produced to an acceptable standard. They were certainly good enough for Myford [Beeston] to sell a version under its own name.

The problem is … those standards appear to have slipped.

MichaelG.

Morning Michael,

I thought the early Vertex were made in China and finished in Taiwan but I could be wrong.

Ron

Myford milling machines were made in Taiwan but tweaked (if necessary) by Myford (i.e. quality control checked) BEFORE they went to the customer. I've had VMC for years and very pleased with it. Michael hits nail on head (see my previous comment).

[Wout Moerman 1Participant @woutmoerman1]

Posted by Michael Gilligan on 15/03/2019 07:49:49:

Good point, Jason … but

(a) the big gear, used in conjuction with a special worm, remains an interesting possibility

Certainly cheap enough to have a play with:

**LINK**

Edited By Michael Gilligan on 15/03/2019 08:08:05

Interesting possibility. But if you zoom in on the picture and look at the spur wheel I think the quality is immediately apparent. But this might be a by QC rejected part which ended up as a photo model?

[HopperParticipant @hopper]

Posted by Wout Moerman 1 on 15/03/2019 09:44:41:

Posted by Michael Gilligan on 15/03/2019 07:49:49:

Good point, Jason … but

(a) the big gear, used in conjuction with a special worm, remains an interesting possibility

Certainly cheap enough to have a play with:

**LINK**

Edited By Michael Gilligan on 15/03/2019 08:08:05

Interesting possibility. But if you zoom in on the picture and look at the spur wheel I think the quality is immediately apparent. But this might be a by QC rejected part which ended up as a photo model?

At that price, that is the quality. What do you think makes all that 'orrible noise when you switch on a cheap angle grinder? It ain't the motor spinning around. It ain't the disc spinning around.

[SillyOldDufferModerator @sillyoldduffer]

Posted by Chris Trice on 15/03/2019 00:49:57:

Posted by SillyOldDuffer on 14/03/2019 20:10:42:

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:

…

…

…

…
…

It's not about chasing tenths of thou's. It's about the failure to meet the basics claimed for the product. One would expect a collet chuck designed to fit a Myford spindle would actually be able to be screwed on and not be too small. It's not unreasonable for the customer to expect the product to actually do that simple thing.

I see buying tools in terms of Risk Management, which boils down to money in the end. Nothing provides an absolute guarantee. Brand-names, high cost, country of manufacture, reputation are all unreliable indicators.

• Equipping the workforce of a professional organisation with unreliable tools is bad business. As stoppages are painfully expensive because overheads carry on regardless it makes good sense to pay full whack for reliable tools, but even this may not save you. HMS Triumph, costing about £400M new in 1991 was found to have one of the oval frames welded in upside down, distorting the hull shape and affecting the submarines performance. I don't know who paid to have it fixed, but given the very high cost, it was probably the customer. At the very least the customer paid for the delay, including the cost of the highly trained crew.
• Second-hand is considerably more risky. The condition of the machine is unknown. It might be good, it might be poor, or it could even be a collection of old bits with an impressive paint job. Professional buyers know what to look for, and a business might buy-in the necessary experience, or insure against the loss. Nothing wrong with taking a calculated risk, but if it goes wrong, the customer's left holding the baby.
• Hobby tools are both an opportunity and a risk. It's true that some items aren't fit for purpose. But, if bought locally from a reputable seller you have a very good chance of getting your money back, or a swap. The risk is quite low – hassle, and perhaps return costs. It's also possible, and the same is true of wonky second-hand purchases, that a hobbyist will happily set to and fix it. Rather than getting hot-under the collar about minor flaws, treat the item as a stepping stone.

I'm grateful that cheap hobby tools are available because they enable me to do what I want at the price I'm prepared to pay. My inexpensive rotary table is typical – it's a bit rough, but it works. Perhaps I've been lucky, but – so far – I haven't received anything unacceptably bad.

A better target for customer rights might be the travel industry. Certain budget airlines have extremely low reputations: extra charges, unreliable, refusing to pay compensation, losing luggage, and contempt for customers. Nonetheless they remain popular, the reason being that most of the time they get you where you want to go at rock-bottom prices. And buying a railway ticket does not guarantee a seat, or that you will be allowed to board the train, or even that the train will run at all…

Dave

[Neil WyattModerator @neilwyatt]

Posted by Michael Gilligan on 14/03/2019 22:18:50:

Posted by Neil Wyatt on 14/03/2019 22:09:51:

Good idea John, a bargain basement (<£5) angle grinder 36-tooth gear might be just the thing for a small rotary table.

.

Agreed … and I think 36 teeth would be considerably more versatile than 47

Only reservation is that angle grinders usually [and intentionally] have loads of backlash … so it might be preferable to make a special pinion.

MichaelG.

I was thinking a suitable worm wheel might be possible, rather than the standard pinion.

These gears are produced in ridiculously large quantities so they are both cheap and generally well made. I used a pair in Southam for the final drive. I'm sure they will happily cope in larger gauges, certainly 5" and have a set put aside for the future.

Neil

[John PParticipant @johnp77052]

Posted by Neil Wyatt 14/03/2019 22:09:51

Good idea John, a bargain basement (<£5) angle grinder 36-tooth
gear might be just the thing for a small rotary table.

Hi Neil,

Not so sure how that a mating worm could be made to work
satisfactory with one of these gears.
The principle of these spiroid gears is the form of the hob is
the same as the worm that is used to drive it.

The photo here shows the gear being cut ,this gear was made
using prototyping wax as it was just an experimental tryout.
A proper gear would need a hob to be made similar to the
style in Heartland gears http://www.itwheartland.com.As can be seen
the thread form is asymmetric.

The position of the centre distance of the hob needs to be
noted down as the worm has to be placed in this exact position
for this to work.
At 60 tooth and 1 module a spur gear would be 62 mm od ,
this spiral gear also 60 tooth is 84 mm od.
As worm and wheel rotary tables have the worm outside the radius
of the wheel the case size is larger than it needs to be to accommodate
this.
As the placement of the spiroid worm is within the radius of the gear
a larger gear could fit within the same size casing of a rotary table.
As far as accuracy is concerned i can't see that it would be any
different to any other generated gear form.
John

[JasonBModerator @jasonb]

I still don't see that giving any more contact than the typical rotary table would and low helix gearwheel ( they are not curved face wormwheels) happy to be proven wrong. I think the reason the rotary tables don't use the curved face of a typical worm wheel is that you would not be able to swing the worm out of mesh as easily as you can using the eccentric mount for the handwheel spindle.

If you look at that spiroid video the pinion is tapered and has a 3 or 4 starts other wise it would not mesh with teh teeth of the gearwheel

[Michael GilliganParticipant @michaelgilligan61133]

Posted by JasonB on 15/03/2019 11:07:05:

If you look at that spiroid video the pinion is tapered and has a 3 or 4 starts other wise it would not mesh with teh teeth of the gearwheel

.

I don't have the drawing skills, or the 3D CAD package, to check it … but I suspect that it would be possible to contrive a single-start worm that would drive one of these wheels. [good enough for Jazz, as Mike said earlier]

MichaelG.

[JasonBModerator @jasonb]

I'm sure something could be made to drive one of those wheels Michael but they were suggested as a way of avoiding stripped gears on conventional rotary tables by offering "full contact" so unless you have a full contact worm you have not gained anything over the original gears and with forever by jazzy.

[Author]

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