Limitations of my lathe.

[ChaiLatte]

View attachment 164520

It is good to know they make these in both right hand and left hand versions (note the direction in which the ones in the hexagons are coiled).

 

[niall Y]

Now here's a thought ............... when I stated earlier, in this thread that I thought the knocking on my lathe was coming from bearings. others suggested that this would happen relative to each revolution of the spindle. This to me appears quite logical. And from this it would then seem odd that the knocking was, in fact, intermittent.

However I've just been playing, with one of the tapered roller bearings on my bench, ( as one does) and I've noticed that for each revolution of the shaft the roller cage only processes part way around. I marked the inner part , the cage and the outer part with Tippex and after a number of revolutions it was difficult to get all the points to exactly align again. I believe there will be a repeat pattern here somewhere, but it might go some way toward explaining why the knocking seemed irregular. after only a few revolutions of the chuck by hand.

 

[Fergie 307]

True - BUT - this feature actually limits the choice of material that can be safely & securely held.

The advantage of ER type is that they can securely hold a range of diameters, mostly -1mm from nominal but below 4mm it's -½mm I'm not sure about the imperial sizes - I only have 2, 1/8" & ¼" (used specifically to hold carbide milling cutters).

Essentially I'm saying that both systems have their pro's & con's - such is life!

Incidentally my ER collets are all 'through bore' so can take longer lengths of material (well up to the limit of my lathe headstock spindle bore). I seldom use this facility since most of my work is 'one-off' prototype but I have used up to 6m lengths in 5C type collets in the dim & distant past when in a production environment. - - - that takes me back to my pre-apprenticeship days!! - - - Ye Gods - 1956!

Should have been more precise. As you say ER collects are through bore, however the holders usually aren't, so you are often limited to a relatively short work piece.

 

[Fergie 307]

Now here's a thought ............... when I stated earlier, in this thread that I thought the knocking on my lathe was coming from bearings. others suggested that this would happen relative to each revolution of the spindle. This to me appears quite logical. And from this it would then seem odd that the knocking was, in fact, intermittent.

However I've just been playing, with one of the tapered roller bearings on my bench, ( as one does) and I've noticed that for each revolution of the shaft the roller cage only processes part way around. I marked the inner part , the cage and the outer part with Tippex and after a number of revolutions it was difficult to get all the points to exactly align again. I believe there will be a repeat pattern here somewhere, but it might go some way toward explaining why the knocking seemed irregular. after only a few revolutions of the chuck by hand.

Good point. If you had a flat or other fault on one side of one roller, this might well not come around in a predictable fashion. Good to know it's fixed, and hopefully not too pricey.

 

[J-G]

Should have been more precise. As you say ER collects are through bore, however the holders usually aren't, so you are often limited to a relatively short work piece.

Ah - as should I (have been more precise!) - I made my own ER Chuck (I did buy the nut - I'm not totally mad!) which fits the spindle thread on my lathe (and fits the register dia.) so I don't have the restriction of being driven by a MT shank - which of course does restrict the length of a component.

 

[J-G]

I believe there will be a repeat pattern here somewhere, but it might go some way toward explaining why the knocking seemed irregular. after only a few revolutions of the chuck by hand.

It's impossible to be absolutely precise since I don't know the dimensions of your particular bearing but in principle, of course the 'cage' has to rotate at a different rate to the cups. Assuming a 60mm OD-35mm ID bearing - and a taper roller 8mm at the large end and 12mm long - - the outer cup will rotate the roller ~7.3 times and the inner cup ~5.3 times each revolution and it should take ~38 revs before the cage and cups 're-align'.

These figures are, as I say, purely theoretical but I'm sure you will understand the concept.

It still wouldn't account for an 'intermittant' knocking - unless you consider regular but not every rev. to be intermittant.

 

[Fergie 307]

Never really examined a taper roller with this sort of issue in detail, but have on large ball races. Problem is the damaged ball often drags or catches, so it doesn't roll round as it should, hence the roughness or catch in the rotation doesn't occur with any predictability. I would imagine the same would probably be true of a damaged roller. At least they weren't the v expensive Gamet ones.

 

[TFrench]

Essentially I'm saying that both systems have their pro's & con's - such is life!

Which is why I have both! I've got almost a full set of Hardinge imperial 5C's in /64th sizes... its taken a while to find them all! Very gratifying to be able to open the drawer on my HLV and pull out the correct collet from the rack.
I was just pointing out the short stock problem with the ER system because if you aren't aware of it it could very easily bite you - and given how much more affordable they are than 5C its someting a newbie to metalwork could quite easily find out the hard way.

 

[J-G]

Very strange how life brings subjects to the fore. I don't think I've used my ER Collets on my lathe this year but yesterday it became abundantly clear that I couldn't complete my latest project without. It so happens that I need to use the 'Gap' in the bed since the work I have to turn won't fit 'over the bed'.

No matter I thought, I'll put the ER chuck on - - except even that is too long! Further thought, "I have that other collet system that didn't sell on eBay". Looked it out and it is a set of about 8 'Hardinge' collets (They are not 5C - probably in the TF series) with a quick release mechanism. By the time it was mounted it was still too long to be comfortable.

Even further thought - - - "I'm sure I had some MT2 collets" - - - sure enough, a virtually unused set of metric MT2 collets from 1 to 12mm were lurking in a seldom viewed cupboard! Spent most of last evening making a proper draw-bar closing nut. I'd previously used a lash up just to test but then made the ER chuck and these collets had gone on the back burner.

For this project they are exactly the right tool; the protrusion from the headstock is less than 5mm, giving me about 40mm of space in the 'Gap' - The job is only 12mm thick but 200mm Ø.