Member postings for Pete Rimmer

I don't do theroetical debate very well I see it as wasted energy. I take your point about the use of the term 'facet' but it's the most fitting terminology I could come up with.

Basically my hobber when it's feeding has very little infeed in fact the feed handle moves like clock's minute hand. Almost all of the 'movement' is the hob teeth passing the blank whilst the blank is constantly rolling so whilst a zero-thickness blank might theoretically receive a flat facet cut ANY thickness of blank will be cut via a simultaeneous action of helical-motion teeth passing through the part whilst it's rolling. It will generate a curve, not a flat.

It produces facets it just doesn't produce flat ones. In a similar vein who would argue that a lathe can't produce a smooth round finish even though it's using a tool that inherently cuts a helix?

It's all a matter of degree.

The gear blank does not stop rotating for each hob tooth to make a cut, so each cut is made not with a flat facet but with a slight rolling action.

Think of it as analogous to filing a curved face in a part. The file is flat but you generate the curve by rolling the file as you push. Hobbing is similar.

Edited By Pete Rimmer on 10/10/2021 20:09:44

Mine was done in 2009 by John. I did have the details on email but they have long gone. I think he used EN40 for the end slug, he machined a parallel pocket in my spindle end, pressed in the slug then machined it to size for the R8 collet. When I fitted it up there was a tiny bit of runout so I tilted the head over to the R8 taper angle, put a lathe tool in the mill chuck and took a skim cut to make the taper run dead true.

https://bbs.homeshopmachinist.net/forum/general/35047-herbert-mill-spindle-r8-conversion

Worth noting that the Herbert spindle through-hole does not quite have the clearance for the R8 drawbar but it's only a few thou so he made a slightly undersized one for me and it's been in use for 12 yrs now. I have to say I can thoroughly recommend it as a modification it opens up a wide range of usefulness being able to use the R8 tooling.

Edited By Pete Rimmer on 07/10/2021 19:04:50

Hello Stan,

I also have an 0V and it also came with the 6 collets in a wooden block. I could not find any other collets or informatio on the taper type and came to the conclusion that they must be particular to the machine.

John Stevenson modified my spindle so it now takes R8 collets which are plentiful. It involved pressing a slug of steel into a recess that he cut into the end and machining the R8 taper into it. I'm very happy with the result and have been using it for quite a few years

I considered adapting another chuck like an autolock to it but decided agaist it to give as much z-height as possible and also keep things as rigid as I could. I think it was a good choice and woud suggest you consider the same.

Does your machine have one Tee slot in the bed or three?

Regards

Pete.

Well done Steve it;s nice to see people thinking about and tackling a problem themselves without having to have their hand held all the way.

Steve you might well damage your lathe If you keep that up. You don't say what lathe is actually is. It could be that your bed is level but the headstock is not pointing straight down it.

The packaging says steel crankshaft but the chips and sparks say iron

That should be plenty good enough for most bench lathes.

If you have a machine with 2 pedestals like a Bantam, the first thing to do sould be to level the bed and fix the feet to the floor, with shims of required to achieve level. I rebuilt a Bantam and as an exercise I put a dial gauge on the saddle and against a part in the spindle, then I moved it about on my workshop slab - the dial gauge swung all over the place just from the variations in floor level and the lathe stood normally on it, and my floor isn't bad at all. It was quite the eye-opener.

Hard to describe in words coherently but easy enough to show.

Your dial is not actually measuring taper as such, I mean it MIGHT be or there might be a taper when it's showing no movement. To measure taper with a dial you'd use a comparator stand.

With the dial on the front and mounted on the saddle it is following the same path that the tool took when it did the cutting. It should therefore give the same reading all along the length. If there is any wear or twist in the bed then where the tool was caused to move away from the centreline of the part, so would the dial point. It would show no change.

With the dial on the opposite side of the part if there was wear or twist causing the tool to move away from the centreline of the part then the same wear or twist would cause the dial to move TOWARDS the centreline which would give a rising reading.

Put the mag base for the dial gauge on the front of the saddle and do your measurement again. That way the dial gauge will be following the path of the tool and should read zero all the way.

That gauge setup is a poor way to check for taper if that's what you're doing Steve. You should be using a micrometer to take measurements at each end of your cylinder. The dial gauge reading can be affected by twist or wear in the bedway.

With respect Brian you only started the thread, you don't get to dictate who may contribute or how. If that's what you want, write a blog. This is a community and participation is encouraged.

If there is an obvious flaw in the concept, the application or the result then it absolutely should be pointed out so that those who come across this thread in the future don't assume that a poor practice is perfectly acceptable just because it's gone unchallenged.

Edited By Pete Rimmer on 02/10/2021 12:19:52

If you look at the drawing posted further up David you'll see that the spi dle taper is given as 4 degrees then it's crossed out and pencilled in as 3.59.30. What does that mean? Both sizes are accommodated within the given tolerances it might be that someone has measured an a tual taper and found that its somewhat less than 4deg but still within tolerance, and decided to record the fact, giving birth to the belief that there are two sizes depending on which side of the Atlantic you're on

The thing is, Hardinge USA supplied the spindle assemblies, with their slightly modified bearings, to the UK for the Feltham machines. They all came from the same place.

Yes you are missing the quadrant that holds the extra gears. It may be that it never had one. The rod you can see poking through is the interlock that prevents you from engaging the extra gears if the gearbox has a feed selected. If you move the lever to the AUS (OUT) position you'll see that the rod sits below flush which would allow the quadrant to move (if it had one).

You can cut all of the metric pitches on the chart as the machine sits right now. The quadrant is only required if you want to cut any other pitch than what's on the chart.

Edited By Pete Rimmer on 30/09/2021 18:08:55

I make it roughly 0.00017" difference which is no difference at all given that the big and small ends have a 7 tenths allowance on the drawing.

Edited By Pete Rimmer on 27/09/2021 19:34:35

Have ZMT started up again under new ownership? They sold up a few years ago.

It's lasted 80+ years so it deserves a sympathetic restoration, and to be used of course!

Pics are in my album folder **LINK**

The nose cover protects the spindle outside taper when using collets in the spindle. It would otherwise be vulnerable to damage.

The drawing could - thoeretically - be used to produce a chuck mount but the fit is so fine that there is no substitute really for having the spindle present for bluing or a decent dummy taper to use as a gauge.

ZMT had a gauge for the grinders to re-finish the spindle taper. It had a pair of marks on it that bracketed the spindle witness mark when the taper was ground to the correct size.

Okay so it turns out this lathe is only a couple of miles from me so I volunteered to look it over.

What I can say is that the lathe appears to be 100% complete and aside from the grimy appearance and very light surface rust is in remarkable condition and seen very little use. Here's a quick rundown.

The model appears to be the "now rare early Zyto" listed on the Lathes website as linked by Michael G above. It has a working backgear with all the teeth in perfect condition. It also appears to have a full set of screwcutting change gears (10 in total) and the tumbler reverse works although the tiny actuating lever needs attention

There is little or no wear apparent on the bedway. The original planing lines are evident all along the length of the top even (faintly) right up to the chuck. There are no digs or dents on it at all that I could see. The swivelling slide is complete and bears no battle scars. I didn't move the slide except to check it's not seized and external inspection shows no wear.

The leadscrew is in fine condition showing little use and certainly very little wear in the usual spot in front of the chuck.

The lathe has two chucks in excellent working condition just a little grubby, a 3-jaw 3" Crown with both sets of jaws and a 4" 4-jaw Burnerd. Both are undamaged with no signs of wear, no corners knocked off or gouges in the chuck or jaw faces The outside jaws are actually pristine. The jaws fit snug and there is a chuck key that fits both chucks.

There's a centre in the tailstock and also a keyless tailstock chuck that looks unused.

Apart from a clean and service the only part that appears to need attention is the drive system. There a vintage motor which turns smoothly but I would certainly suspect the rubber insulation on the internal wiring before putting it into service. There is a flat leather belt that is perished but that could be replaced with a poly-vee belt very easily.

All in all, a cracking little lathe with loads of potential if you look beyond the grime and put in a few hours of cleaning and fettling effort. I've advised Becky that it's worth every penny of £200 and perhaps a little more given the completeness and condition.

This is going to make a very nice little lathe for someone

Yep:

**LINK**

A fascinating read and the archive version is handily scanned so as to be searchable. It seems that the DP system was originated by (Austrian born) Bodmer here in England but adopted and popularised by Brown & Sharpe.

Edited By Pete Rimmer on 26/09/2021 11:56:34