2 questions - threading silver steel; tightening bar in the chuck

     At the risk of going even further off-post, I would be interested to hear from

   Meyrick whether he has had a chance to do a 'forensic' on his old bearings. It

   seems to me that they must have been well made of bad material since they

   performed very well but had a short life.  Perhaps some Icelandic dust got at

   them

Its a Mitutoyo that reads to 5 places of decimals.

 

3 places is thou. 4 is tenths and the 5th is hundredths. It reads to 1/2 hundredths. So does my M&W 1-2". I ve been a bit casual about figures lately (!) but 5 places is hundredths. 

 

Metric they read to .001mm

 

I admit setting the lathe up like that was a bit  of luck. I'd have settled for 1/2thou over 8", but I popped a bit of shim in and torqued it down and that's how it came out.

 

The forensics. The bearings were as the Chinese adjusted them, and they are oil lubricated. There's the usual little collector slot and the oil level has been OK.  Looks to me as if there had been a misalignment of the wedge angle in the tapers,  because you could see a narrow ring where the top surface had worn, and on the outer side of the race track the bearings appeared unworn. That would square with the symptom, which was taper under load - if you had near line contact - but no detectable runout.

 

The new bearings are excellent  - mind you so they should be at that price.

 

 

Oh sure - its just an industry standard digital. I like it because it is so easy to read. The 2" M&W I wasn't going to buy because they are very expensive, but they were on offer recently so I did a bit of overtime.

 

I didn't buy them for the accuracy/definition - more for the waterproofing . You can pretty well dunk both in coolant and they don't blink - and you may have twigged, I like coolant. 

 

I don't work in 1/100ths, or even tenths. I like to hit a diameter to +/-2 tenths. Thats what GHT reckoned was the standard for model engineers, so that's what I work to.

 

For the cut to fit boys, personally I find such accuracy is not difficult to achieve if one works methodically, and it saves a lot of time, because bits fit in the way they are supposed to. However if others want to do it differently thats just a matter of choice. Nevertheless I see no purpose in having a good lathe  if the measuring kit is not as good as the machinery. To me thats like having a racehorse and using it to pull a cart.

 

Gents,

 

Back again after my 15th April post. Please accept many apologies for my delayed responses ("work-work" didn't just call, it SHOUTED!) - especially for such a long-delayed response from me after I seemed to stir up a bit of a hornet's nest (inadvertently, I do assure you all) .

 

But most of all, MANY thanks to those who have made so very many valuable comments & suggestions. Some sepecific responses to Q's that some of you have asked follow:

 

For Versaboss (Hansruedi): My lathe is an "Einhell MTB 3000". I have several pix which I shall try to post when I've finished this post. You'll see (if my posting pix works) that it's an "Asian-special Mini Lathe", but after some checking with the Minilathe web site in USA it seems that this particular model comes from a company called Red Dog (true!), rather than the more common Sieg. As you're in CH, you may like to know that it came from Coop DIY (on sale) "complete with" a 3 inch (75 mm) 3 jaw chuck and nothing else at all! So I made a special order thru Coop to Einhell which about a week later netted a set of 10 mm carbide tipped lathe tools, a fixed steady, and a faceplate. NOTHING else available! So all the rest (tailstock drill chuck; hard & soft centres; centre drills; several more chucks - 3 & 4 jaw; dog; etc, plus the QCTP; all came from LMS in the USA - whom I can heartily recommend BTW - usual disclaimers). I live just outside Liestal (NW Schweiz) so Pestalozzi was too far really, but Debrunner & Acifer are just down the road in Frenkendorf. I went there to buy some 5 mm, 10 mm & 15 mm silver steel (because I want to have a go at making some own lathe tools one day) expecting to get the metric equivalent of 13 inch lengths. To cut a v long story short (and for an Englishman my Schweizerdootsch is not too bad), I ended up having to buy a 2 metre length of each diameter as their minimum order. (So nobody needs to wonder anymore why I fancied trying to make a new toolpost stud out of 10 mm dia silver steel)!  And last point Hansruedi, in my set up the base of my toolpost is not sitting on a 10 mm nut - I've made a temporary "spacer" (until I can bore out the base of the toolposts) to give what I thought/hoped would be an adequate base area for the toolposst underside to rest on.

 

For circlip: Thanks for that. Noted, will do. 

 

For KWIL: Yes, thanks for the comment on the QCTP. I've had the same problem with "incompatible compatible QCTP". Hopefully, if my posting pix goes OK, you can see my "problem".

 

For gedeon spillet: Thanks for the tip about tigthening the tool into the (Chinese) toolpost. It's obvious when one thinks about it (so why didn't I see it before you pointed it out?). From now on I'll tighten tools in the way you describe.

 

For Ramon Wilson: Now I'm really going to hang my head in shame!! I had checked all the gibs (on both the top and cross slides), but did it again anyway. But still the tip of my boring tool was visibly moving (about 1 mm) as the cut started. And no, it wasn't carriage/ways slop either - as I say, hanging my head in shame, in the end I found a piece of swarf jammed between the underside of the toolpost and the (temporary) nut and spacer (see photo - if it works). What a dummy!!!!

 

Lastly, for MGJ: No I'm definitely NOT a dab hand with a grinder (I need to learn - and quite frankly it frightens me silly). So that's the reason why I have carbide tipped (cemented or brazed) lathe tools (plus the fact that that's what I got when I ordered a set from the lathe "manufacturer" - see above comment, addressed to versaboss.

 

OK, I think I covered all the points (until you all thread-drifted away to talk about mics, etc

 

Once again VERY many thanks to you all - especially for your patience. Tomorrow morning I'll be in the shop trying to put all your good advice into practice.

 

Krgds

AES  

Gents,

 

Just to add to all the above, posting photos here is dead easy (even for a deadhead like me), so see my album to "illustrate" some of the above points.

 

I apologise for the poor focus on 2 of the closeup shots - I was trying to get too close.

 

Krgds

AES

Posted by Martin W on 16/04/2010 15:57:20:

 

 

Hi Martin,

 

They're not that intelligent, believe me.  The problem is , they think they are

Terry

Posted by Ian S C on 17/04/2010 12:11:00:
Meyrick, iI imagine that your mic is a digital one, as I'v never heard of a mechanical type with that sort of definition, you would just about need temperature controled condions to maintain accuracy, you realy need that for 0.0001" let alone a 1/10 of that. Sorry we're wandering. Ian S C

 

0.00001" is about 0.00025mm - 250 nm. That's less than a wavelength of red light. So i vote with Ian's scepticism here

 

Neil

Please guys,

 

You should know better than question Meyrick.  He who is so superior to us mortals with expertise and experience in all fields of human endeavour.  Surely it is enough to sit round his feet and bask in the glory of being present to such a superior being and wonder at his glorious knowledge.

 

Our poor human offerings are  are meaningless in the face of such perfection.

Posted by Stub Mandrel on 05/05/2010 19:40:47:

Hi All

 

It is worth noting that Gloster Tooling Supplies, amongst others, are offering for  about  £40, 0-25mm, digital micrometers reading to 0.00005" or 0.001mm (rated to IP54) which is the resolution quoted by MGJ for his Mitutoyo. Also on Ebay one can occasionally pick Mitutoyo instruments, second hand, with the same resolution for similar prices. So measuring to a resolution of 1/2 of 1/100 of a thou looks achievable. Certainly in a controlled environment but not in my shed which is hot in summer and bloody cold in winter  so I just hope that things expand and contract in a similar manner and still fit at the end.

 

Mind you if someone wants to try to work to these tolerances, well beyond my capabilities , then why not and if they achieve it more power to their elbow I say. I wish I had the patience but getting down to close on +/- 0.02mm will do me for now.

 

Have fun and keep your chucks tight.

 

Regards

 

 

Martin

 

PS

 

Just done a quick trawl on Ebay and it looks as if most commercial suppliers are offering digital micrometers with a resolution of 0.001mm or 0.00005" as standard!!! Looks as if we are going to have to tighten our gibs, sharpen our tools and offset the top slides to meet the challenges of the extra decimal place on offer . Just when I thought I was getting close to being an engineer, amateur of course .

Apart from all the joking, in the inspection dept I worked in we had manual micrometers which measured to a 1/10th of a thou.  They had a vernier gauge around the barrel which measured at least down to 1/10th.

 

However they had to be kept in a temp controlled environment as did the items to be measured.  These had to be held in the controlled environment until the temperature was stabilised. i.e . the Standard of 20deg C (68F).  Unless you can control temperature of equipment and components to these standards the fine measurements we are discussing are meaningless hence the development of tolerance systems to accomodate variations.

 

And of course if you are using components in a heated environment such as any heat engine the fine accuracy goes out of the window. Especially if using materials of different co-efficient of linear expansion which inevitably we are.

 

The toolroom was a different matter of course.

 

Terry

Posted by Stub Mandrel on 05/05/2010 19:40:47:

 Just a minor correction,

 

A nanometre (nanometer for our North American friends)  is equal to 1 billionth of a metre i.e nine zeros.  So 250 nm would have six zeros before the number i.e. 0.000000250.  However I agree about the accuracy and the difficulty in obtaining Meyrick's level of accuracy in a normal workshop.  As well as the need for temperature control there is a need for consistent pressure on the vernier or micrometer.  We all know that a relatively small variation in pressure can make a thou or two difference so what is the point in trying to achieve a hundredth of a thou.

 

For such accuracy we used comparators which did not rely on manual manipulation.

 

Terry

Hi AES

You mentioned earlier in your post that you were having difficulty obtaining small quantities of various steels.  Here in Melbourne I found Bohler-Udeholm  very helpful and quite willing to supply small cut to size peices of practicaly anything.  I have recently been buying bits of 120 and 1045 but they have everything from Silver steel to aluminiums, cast iron in various grades, high speed steels, iconel, key way steels etc.

They have offices all over Europe, here is the seller in Switzerland

 

Hi Lawrie,

 

Thanks v much for that info. Printed out n saved!

 

Krgds

AES

Just a quick reply to Versaboss about billions etc.

If you have a look at this site http://www.simetric.co.uk/siprefix.htm you will find that the accepted international standard for a billion is 1000 x 1,000,000.  Note also that it is a UK site.

 

 

 Not such a big oops Hansrudolf.  In the UK the American Billion is now generally accepted as the standard by most (although some anti metric, anti European Brits may disagree)   not a Million Million which would of course have 12 zeros.