rotary table problem

[Michael GilliganParticipant @michaelgilligan61133]

Posted by larry Phelan on 16/03/2017 13:42:43:

Hi everyone,

Back to the old rotary table …

The truth is that it was/is out by 25 divs,each one 0.01mm,a total of 0.25 mm. A bit much,you might say. This is much as I seem to remember it was the first time I checked it;

[…]

Someone asked about the cert which came with it,so I will try and enclose a picture of it.While all the tests are marked off as OK, you will note that no one signed it ! I wonder why?

Sorry,was unable to get the picture out from my picture files. [I can hear you guys saying "can this guy do anything? ].

.

No wonder you couldn't cut a decent hexagon when you tried !!

Regarding posting of pictures:

Here is the Lesson according to Neil: **LINK**

http://www.model-engineer.co.uk/forums/postings.asp?th=103028&p=1

MichaelG.

[larry PhelanParticipant @larryphelan54019]

Talking about rotary tables [ I know, I know,will he ever stop about them ] ,was just looking at some of them on Ebay,from India.Prices seem very good,does anyone know about the quality? I suppose they could not be much worse than the one I have. I have no plans to buy right now,just wondering.

By the way,I think I did manage to send a picture of my "Test Cert ". My computer skills leave a lot to be desired,since in my day even calculators were not even heard of,never mind computers.Anyone remember those days when you worked everything out the long way ? Anyone out there who still remembers using log tables?

Happy days ! Now you click a button and hope it gives you the right answer.

As an after thought,when I was checking the "Instruction book "which came with my table,I found several errors relating to the spacing of holes ect,so dont rely too much on these charts,do a dry run first. Bit late to find out if you are spacing 50 or more holes !

[MikelkieParticipant @mikelkie]

Bought a dividing head of so called reputable urasian makers, quite new too still in wooden box, however when tried to use it, ifound that the the spindle bore MT3 was not concentric to the axis. Took it back to the used tools shop lost some money and bought a used Correa (Spanish make) perfect, and i don't suffer from buyers remorse any more. I'm not impressed by the good looks or price of eastern stuff anymore.

Mike

[larry PhelanParticipant @larryphelan54019]

Hi Everyone , my ,computer decided to act up today [what else can go wrong? ]

Some other member posted an item regarding a dividing head which he had bought,which was just about as good as my rotary table. Seems like there,s a lot of stuff like that out there,it gives a whole new meaning to the term "Inspection" How this stuff ever gets passed is beond me.

I had intended to post some pictures of some mods I made to my cheap bandsaw,but since I seem to have lost everything,thanks to "updates" being installed,without even asking for them,I will have to reload them and then try putting them in my album

The main change I made was mounting the saw on a proper stand,with wheels and fitting a coolant pump [a pump from an old washing machine ]. I t works perfectly,has done for the last 10 years,and does wonders for blade life.

If I can get this thing up and running again,I will try posting the pictures.

[“Bill Hancox”Participant @billhancox]

Posted by larry Phelan on 18/03/2017 13:17:39:

Some other member posted an item regarding a dividing head which he had bought,which was just about as good as my rotary table. Seems like there,s a lot of stuff like that out there,it gives a whole new meaning to the term "Inspection" How this stuff ever gets passed is beond me.

I believe we used to refer to this as the left hand not knowing what the right hand is doing. Most tooling these days is manufactured by machine operators (not machinists) using CNC machinery. There are probably not many machine operators and inspectors (if there any inspectors at all) who are capable of identifying errors in the CNC programs they are using (CNC programs are probably subbed out to some obscure, quasi-qualified entity in Neverland anyway). There are also many items these days that are not manufactured in-house but are instead being assembled from outsourced components.

Bill

[larry PhelanParticipant @larryphelan54019]

Just reading the reply from Bill.I think he hit the nail right on the head.I used to think CNC was supposed to do away with errors,seems like I was wrong. Going through the chart in my "Instruction Manual ", I came across several errors regarding hole spacing and all these at the lower end of the scale. I hate to think what the upper level is like,should make gear cutting very interesting. The "Manual" itself must have been written by a 3rd rate bottle washer from the local takeaway,it,s almost impossible to understand.

In one case,in order to space 13 holes,they call for 6 full turns plus 30 holes on a 39 circle. This of course does not work out. What does work is 36 [yes 36 ]holes on the 39 hole circle.But it,s not just that simple,because you cannot position the sector arms to achieve this [same think happens in a few other cases ] I got around this by making a one-off sector arm and using both sides of it. Might sound a bit iffy but it works and I suppose it blends in well with the rest of the table; At this stage,nothing would surprise me. Just picture finding this out when you are trying to cut 60 teeth!.

On another topic,I mentioned about a mod I had made to my bandsaw. I have taken two pictures of it in case it might be of interest to anyone else [this does work ]

[JohnFParticipant @johnf59703]

Larry Phelan wrote

My computer skills leave a lot to be desired,since in my day even calculators were not even heard of,never mind computers.Anyone remember those days when you worked everything out the long way ? Anyone out there who still remembers using log tables?

I sure do Larry, Seven figure logs and trig tables and Brunsviga pinwheel calculating machine for adds takes, guzintas and square roots! Before the machine it was all longhand, eventually the firm provided a Texas Instruments scientific calculator and at first when it produced an answer we would "just check it " the old way ! Lack of trust ! About that time Mr Sinclair made a calculator but it took a lot of thinking time before it came up with an answer Happy days.

John

[John Stevenson 1Participant @johnstevenson1]

Hauser still make a low profile 6" table with a test cert that they will stand by.

Only problem is last time I looked they were £3,200 a pop

[SillyOldDufferModerator @sillyoldduffer]

At school we had a second-hand motorised mechanical calculator that sometimes took several minutes to complete a division. Also, it would occasionally fail to realise that the sum was finished. After clattering for a while, it would print a number with no relation to the actual answer. I guess it had been given to the school after disgracing an accountant!

[duncan webster 1Participant @duncanwebster1]

Posted by larry Phelan on 18/03/2017 15:48:03:

Just reading the reply from Bill.I think he hit the nail right on the head.I used to think CNC was supposed to do away with errors,seems like I was wrong. Going through the chart in my "Instruction Manual ", I came across several errors regarding hole spacing and all these at the lower end of the scale. I hate to think what the upper level is like,should make gear cutting very interesting. The "Manual" itself must have been written by a 3rd rate bottle washer from the local takeaway,it,s almost impossible to understand.

In one case,in order to space 13 holes,they call for 6 full turns plus 30 holes on a 39 circle. This of course does not work out. What does work is 36 [yes 36 ]holes on the 39 hole circle.But it,s not just that simple,because you cannot position the sector arms to achieve this [same think happens in a few other cases ] I got around this by making a one-off sector arm and using both sides of it. Might sound a bit iffy but it works and I suppose it blends in well with the rest of the table; At this stage,nothing would surprise me. Just picture finding this out when you are trying to cut 60 teeth!.

On another topic,I mentioned about a mod I had made to my bandsaw. I have taken two pictures of it in case it might be of interest to anyone else [this does work ]

CNC ensures that exactly the same error is made every time, but even in the olden days you wouldn't have had a fully skilled man on mass production jobs, semi skilled at best. Remember the old wartime films of young women operating capstans, and before the feminists jump down my throat I'm not suggesting you couldn't have a fully skilled woman.

[john swift 1Participant @johnswift1]

" Remember the old wartime films of young women operating capstans "

yes , my mum was one of the many Ward 2D(?) capstan operators during the war

John

[JonParticipant @jon]

I do like that one Duncan very diplomatic "CNC ensures that exactly the same error is made every time"

Larry, did you knock the MT taper in?
If not there will be play or set off axis.

Think its a real poor way of location using the bore/MT to align from, mines permanently bolted to table direct undisturbed for decades.
Adding extras leads to more to go wrong or move or even create additional errors.

Machined out soft jaws (one size does all) on my RT with chuck in situ. Drop an item in three times and still get three different runouts up to 0.25mm. Serious work will always need clocking up.

[John Stevenson 1Participant @johnstevenson1]

Posted by Jon on 18/03/2017 23:12:14:

Machined out soft jaws (one size does all) on my RT with chuck in situ. Drop an item in three times and still get three different runouts up to 0.25mm.

Your scroll is worn on the chuck, it's the only way you can have an error with machined soft jaws fitted.

[Maurice Cox 1Participant @mauricecox1]

Sorry I've come a bit late to this thread; going right back to the beginning, Chester can't say the can't help as they no longer stock that model. Your contract is with them, and they have sold you goods that are "not of merchantable quality" or possibly "unfit for purpose". You are entitled to an exchange item or your money back; and it is your choice which you have. If they refused you could have contacted your local trading standards office. This is now not possible as you have modified the item, but it is something to remember in future.

Maurice

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Michael Gilligan on 04/03/2017 13:55:37:

Posted by John Stevenson on 04/03/2017 13:38:43:

Micheal, what good will seeing a certificate give you after you have already said it's not worth the paper it;s written on ?

.

John,

The certificate is evidence for, or against, my 'case' …

Larry mentioned a certificate, but did not tell us what it certified. … It is plausible ['though unlikely] that the certificate is so worded that Larry's table is within spec.

We all have our niche areas of interest; and one of mine is Probity.

MichaelG.

.

Maurice,

May I refer you back to my earlier comments ^^^

'Merchantable Quality' 'Fitness for purpose' and such concepts are much more meaningful in the context of an item which is purchased on the basis of a specification. … I have little doubt that Larry's table could be described as "a rotary table", and therefore, unless the concentricity of the taper was specified [and/or its intended purpose described] the case would be difficult to prosecute. Chester, or the Manufacturer, might simply say that the taper was provided for convenient rough-location, and not intended as a register.

Yes, of course, it is very convenient to have the bore concentric with the axis of rotation … but …

MichaelG.

.

P.S. [just for clarity] John slightly mis-quoted me: What I originally wrote included the word "probably":

"… as for the Certificate  it's probably not worth the paper it's written on; but I would be interested to see a copy."

Edited By Michael Gilligan on 19/03/2017 08:49:57

[Douglas JohnstonParticipant @douglasjohnston98463]

I am very surprised that a company would not honour the sale of goods act. If the item was clearly out of spec there should have been no question about replacement or refund, even if there was a delay in noticing the problem.

Doug

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Douglas Johnston on 19/03/2017 09:00:12:

I am very surprised that a company would not honour the sale of goods act. If the item was clearly out of spec there should have been no question about replacement or refund, even if there was a delay in noticing the problem.

.

Doug,

I'm sorry to labour this but, that's an important point:

Was it "clearly out of spec"

… or simply outside the buyer's un-agreed assumptions ?

MichaelG.

[Michael GilliganParticipant @michaelgilligan61133]

I don't intend to pursue this any further

< cue cheers from the chorus >

but, for anyone interested, here are Chester's current 'Hobby Store' Terms & Conditions:

**LINK**

http://www.chesterhobbystore.com/terms.asp

These do not look unfair or unreasonable ; but they do merit careful reading.

Always bear in mind that, unless you make some special side-agreement, you are accepting the Seller's [fair and reasonable] terms by the act of making a purchase.

MichaelG.

[SillyOldDufferModerator @sillyoldduffer]

Looks like Larry has a poor example. I had my Warco supplied HV6 out to play today and took the opportunity to clock it with a DTI.

In the horizontal position, the 'run-out' of the table's centre hole was a bit over one division, which my inexpensive DTI claims to be 0.01mm. Annoyingly, the certificate has gone walk-about so I can't reveal what it said.

Dave

PS I tried the 13 division set-up without any problem with the standard clock-hands.  Presumably Larry's table isn't an HV6 clone.

Edited By SillyOldDuffer on 20/03/2017 16:51:41

[larry PhelanParticipant @larryphelan54019]

Someone took me to task for going on about my rotary table and expressed the hope that I was not going to pursue it any further. I,m not ,I never had any intention of pursuing the matter with Chester since too much time had elapsed anyway.I simply wanted to know what if anything could be done about it,but I got my answer there alright !

Some of the other members have been more helpful since it seems that I am not the only one who has been unlucky in this way. When you ask about the spec,I think an error of 0.25 mm should answer your question.

Considering the range of other equipment I bought from Chester,which gave no bother,I was somewhat surprised and disappointed with the table,that,s all. I thank you for your interest in the matter,but dont lose any sleep over it,life is too short for that.

[Author]

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