Rotary Table Failure

[John Stevenson 1Participant @johnstevenson1]

Usually 120 on the larger tables but not really relevant as they often use the same pitch of worm and hob so tooth strength is the same but you often get more engagement as it’s a larger diameter worm

[John PParticipant @johnp77052]

Posted by KWIL 10/08/2016 10:41:27
RT table has some wraparound on the wormwheel of course.

The photo in album rotary table shows 2 hobbed wormwheels
the large one is for a CES table casting and is a full wormwheel .

I would think the price would increase considerably on these
Vertex type tables if they were made with a wraparound wheel.

These 6 inch rotary tables seem to be all similar obtained
under different badge names ,don't know if it is worth repairing
these ,Warco selling these now for £129.00 inc delivery with
a set of 3 dividing plates.

I only repaired mine because it was a givaway and the piece of
bronze was free.

John

[AjohnwParticipant @ajohnw51620]

The CES one is just an ordinary gear with the teeth angled to match the worm. I asked him a long time ago about hobbing them and he just said no gashed. He wasn't too happy about having to thin the castings down to allow machining on a Myford in the gap. It used to be a Boxford / Harrison college / school project.

Given my background I wanted 40T but suppose I wont need to mill spirals or scrolls at home.

John

–

[Paul LousickParticipant @paullousick59116]

Hi,

I have been away for a week (driving a full size Fowler traction engine. Someone has to do it !!) and have just read your comments. Thanks for the feedback.

I have a 6" Yuasa rotary table and the worm gear has 90 teeth. It was lubricated with grease but was cleaned prior to taking the photo. The data sheet below states that it is suitable for circular cutting.

This is one of the responses from Yuasa USA :-

" Because this manual was translated from Japanese to English so when they say: High Precision Rotary Table is widely used for circular cutting work, angle setting, boring, spot-facing and similar work in conjunction with a milling machine.

What they mean by in conjunction with a milling machine is that you can put this table on a milling machine to hold you part and the milling machine makes the circular cuts and such. It doesn't mean the table can make circular cuts to make circular cuts with a milling machine you would lock your part to table then clamp table with the 2 brake shoes so table doesn't move and the milling machine would make the circular cuts on your part while you part and rotary table are stationary not moving. it doesn't mean milling machine just stays stationary cutting while you turn rotary table ".

And also from Yuasa :- "Its the same thing on page 4 of the manual says can do center cuts in conjunction with a tailstock. this doesn't mean the tailstock makes the center cuts it just holds you part center so you can make center cuts with lets say a mill or something ".

???? How else do you make a curved cut on a standard mill without turning the RTable ????

Paul.

[PeroParticipant @pero]

Is it possible to get an English translation of the response from Yuasa USA?

Pero

[Peter KroghParticipant @peterkrogh76576]

Excuse the **** outta me but if a rotary table is not intended to rotate a part while a cutter cuts the part, then what the **** is a rotary table for????? Rotating something so it may be admired??

I call BS on these excuses…

Pete

[HopperParticipant @hopper]

Comparing the pic in the OP and the pic that Jasonb posted it appears the OP Yuasa gear is just a helical gear with point contact only as JS pointed out, so suitable for positioning only and not for power transmission. Jason's gear appears to be a properly hobbed worm wheel with full contact as evidenced by the scallops on the teeth, and so suitable for power transmission such as taking circular cuts etc. Even so, it looks like the cast iron in the OP pic is not very hard or tough, judging on the way it has crumbled into coarse powder. Disappointingly poor quality of design and materials in a once-respected brand name. Sadly it seems to be increasingly common practice these days. This quarter's profit is all that seems to matter.

[HopperParticipant @hopper]

Posted by Paul Lousick on 18/08/2016 02:24:15:

…. It doesn't mean the table can make circular cuts to make circular cuts with a milling machine you would lock your part to table then clamp table with the 2 brake shoes so table doesn't move and the milling machine would make the circular cuts on your part while you part and rotary table are stationary not moving. it doesn't mean milling machine just stays stationary cutting while you turn rotary table ".

Sheer bollocks. If a milling machine could make circular cuts why would you need a rotary table?

You purchased the RT based on the English language information provided. If it can't do what it says in English, you should get your English money back. A failure in translation is their responsibility, not yours. (If there really was one).

Definitely NOT FIT FOR PURPOSE as described in the sales literature in black and white in plain English.

[Paul LousickParticipant @paullousick59116]

Pero: This is the response from Yuasa, USA

Hopper: My comments exactly. How else do you make a circular cut and if there is a translation problem in the documentation it is the fault of Yuasa. I will be pushing this point with them to resolve the matter.

Even if the worm gear is not suitable for power transmission. there is nothing in the documentation that I have that states that the table should not be used to make a circular cut.

Does anyone have a contact address for the Yuasa head office in Japan and for a cunsumer/fair trading department, etc in the USA where I can lodge a complaint.

Regards, Paul.

Edited By Paul Lousick on 18/08/2016 07:01:50

[JasonBModerator @jasonb]

My gear is not hobbed just straight cut like Pauls. Any "scallops" are just where the contact has polished the surface and the grease taken the shape of the worm.

I would ask them why they make the distinction between precision being able to do circular cuts and standard not if there is no difference in how they can be used.

J

 

PS don't show them any photo's of you 6" traction engine bits on the rotary table

Edited By JasonB on 18/08/2016 08:26:45

[Chris Evans 6Participant @chrisevans6]

This is all rather worrying, I recently ( in last 12 months ) bought a Vertex 10" rotary table with the facility to use vertical. It was new and boxed bought for £99 so very cheap. I then sold my British made Elliot 10" table to recover most of the cost. Now thinking I should have kept the Elliot.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Chris Evans 6 on 18/08/2016 09:16:00:

This is all rather worrying, I recently ( in last 12 months ) bought a Vertex 10" rotary table with the facility to use vertical. It was new and boxed bought for £99 so very cheap. I then sold my British made Elliot 10" table to recover most of the cost. Now thinking I should have kept the Elliot.

.

Can't complain at the price of that Vertex, Chis !!

But I'm sure you are right about the Elliot.

MichaelG.

[PeroParticipant @pero]

Hi Paul

I recognized that the quotes were from Yuasa USA, it was the grammar that concerned me. I think some of my Chinglish manuals show a higher degree of clarity!

I hope my Vertex rotary tables (4) perform a little better than the Yuasa table.

Pero

[MWParticipant @mw27036]

So we've established that the Yuasa RT is only about as useful as a precision potters wheel?

Michael W

[JasonBModerator @jasonb]

To be fair, Paul has thrown some quite large pots on it.

[MuzzerParticipant @muzzer]

I expect it's a Chinese import with a Yuasa badge on it. Looks suspiciously like the one I bought straight off the boat.

Hilariously illiterate response from the Mercan rep. Perhaps their Chinese suppliers could translate it into English for you. Sounds as if he would be challenged to tie his own shoe laces and probably never seen a machine tool in his life. He probably believes it is his job to fend you off.

Of course, the culture in US is that once you have bought something, it is your job to make the manufacturer (not the retailer) live up to his responsibilities. You have to beg them for an "RMA", otherwise sending it back will be pointless. They are also stuck in the past and consider a 12 month warranty to be sufficient, after which you can go whistle. We have a very different situation in the UK.

These Vertex-type RTs all have an eccentric arrangement for controlling the backlash between the worm and wheel – was this properly adjusted? Obviously failure to do so will result in significantly higher point contact loads and wear – and finally jumping / damage.

[Tony Pratt 1Participant @tonypratt1]

Sheer bollocks. If a milling machine could make circular cuts why would you need a rotary table?

You purchased the RT based on the English language information provided. If it can't do what it says in English, you should get your English money back. A failure in translation is their responsibility, not yours. (If there really was one).

Definitely NOT FIT FOR PURPOSE as described in the sales literature in black and white in plain English.

Agreed, it's definitely 'not fit for purpose'

Tony

[JasonBModerator @jasonb]

Paul is this a second rotary table and third gear you have stripped? I only ask as last year you showed this photo which is of another table going by the oil grooves and this post is about a Yuasa that has stripped two gears in the same way. Does seem a bit odd that 3 gears strip for one user?

My thoughts are that some of the work you are expecting this size table to do on your half scale traction engine may be beyond its design purpose rather than it being unfit for purpose.

Edited By JasonB on 18/08/2016 14:20:20

[KWILParticipant @kwil]

Jason.

Interesting photo, if you look towards right hand side where the tooth removal is worst and then move your eyes to the left, it looks like the worm wound out of engagement just leaving a scar.?

[Paul LousickParticipant @paullousick59116]

This is a replacement for the rotary table (which I purchased second hand) and purchased a replacement worm gear after it was damaged. BUT, because of previous experience, I used a smaller diameter cutter, made sure that the RT gears were fully engaged and only made light cuts to reduce the loading on the gears. Used conventional milling direction and had table clamps lightly engaged to eliminate backlash problems.

The worm gear is very soft and cuts easily with a file. Not sure but think it is cast iron. The broken teeth had crumbled and not sheared off, like it would with steel.

My main complaint is the way Yuasa have responded. I would have accepted any reasonable offer for a replacement part but now will push then further, even if only for my satisfaction.

Paul

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Paul Lousick on 19/08/2016 08:02:02:

… The worm gear is very soft and cuts easily with a file. Not sure but think it is cast iron. The broken teeth had crumbled and not sheared off, like it would with steel.

My main complaint is the way Yuasa have responded. I would have accepted any reasonable offer for a replacement part but now will push then further, even if only for my satisfaction.

.

Spot on, Paul … We're with you all the way.

MichaelG.

.

P.S. … Regarding the crumbling of the teeth:

It looks like a simple matter of weak design, and/or poor material … But one possibility might be that you were getting high frequency chattering [starting at the cutting tool, but feeding back to the worm/gear interface]: It's therefore conceivable that your gentle feed might have been counter-productive, and that more pressure would have overcome any backlash. That said: the thing is still clearly not fit for moderate work, and, if it was only intended for indexing and drilling, then they should have said so !!

[JasonBModerator @jasonb]

I suppose it depends on moderate work, cutting weld prep chamfers on 10mm steel boiler plate would be a cutting length of around 14mm and an insert cutter needs a bit more force than an HSS one.

the 10" dia cuts through the boiler plate may also just have been beyond what teh table is really capable of.

Wormwheel on mine looks to be cast iron don't know if they use SG or just plain old grey iron probably the later.

 

I would be interested to know what others feel is the sort of work a 6" table should be fit to perform? Having only done engineering as a hobby I have always treated my machines as such, do those in industry expect more from them?

Edited By JasonB on 19/08/2016 08:43:27

[Paul LousickParticipant @paullousick59116]

The last job with the replacement gear wheel was not as heavy as when I machined the boiler plates. Cleaning up the perimeter of a 7" dia plate (previously cut roughly to size with an angle grinder), 6mm thick, 8mm cutter, less than 1mm deep and 1-3mm wide cuts. Slow feed with the RT clamps slightly on.

Paul.

[HopperParticipant @hopper]

Posted by Paul Lousick on 18/08/2016 07:00:34:…

Does anyone have a contact address for the Yuasa head office in Japan and for a cunsumer/fair trading department, etc in the USA where I can lodge a complaint.

I would think your avenue of redress would be with the retailer you bought the RT from, rather than with Yuasa themselves. And if you are in the US, then the Federal consumer complaints dept would be the place to lodge, see here: **LINK**

You should have a pretty good case armed with the English language brochures that state in plain English that rotary cutting is OK, then their lame excuse that it isnt but they got the translation wrong. Seems pretty cut and dried really.

[HopperParticipant @hopper]

Posted by Paul Lousick on 19/08/2016 09:19:08:

The last job with the replacement gear wheel was not as heavy as when I machined the boiler plates. Cleaning up the perimeter of a 7" dia plate (previously cut roughly to size with an angle grinder), 6mm thick, 8mm cutter, less than 1mm deep and 1-3mm wide cuts. Slow feed with the RT clamps slightly on.

Paul.

How hard did you have to wrench on the handle to feed the table around while doing this? Finger pressure? Full hand pressure? Full wrist and elbow pressure? Any harder than you would normally expect to hand feed the milling machine table when making a straight cut? (Though, itseems that an 8mm cutter would snap off if excess pressure were applied.)

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