KERRY TYPE A.G. LATHE

[Michael GilliganParticipant @michaelgilligan61133]

Good analysis, Hopper

… But it’s still a joy to see what can be done in the pursuit of perfection: **LINK**

http://lathes.co.uk/bryantsymons/index.html

MichaelG.

[Howard LewisParticipant @howardlewis46836]

Scan was a .pdf which cannot be uploaded to an Album.

So will photograph and add to Album later.

Watch this space!

Howardu

[Howard LewisParticipant @howardlewis46836]

Photo of Illustration now in my Album, headed TAPER TURNING OFFSET, with reference to this thread.

Howard

[Green TechieParticipant @greentechie]

Wow, you gentlemen are an absolute mine of information, thank you all for the replies.

Fascinating to get the low down on the issues with screw cutting gear accuracy, or lack of them!

I've only just had a chance to catch up on the thread, but I will have a go at following Clive's taper turning instructions as soon as I get some time. I have the AG Mk.3, so I do have the T slot mentioned.

Thank you Howard for the keyway cutting tips. I am tempted to get the softer metal gears and try that. Also interesting to see the photo and instructions for turning tapers between centres.

I will check out Tony's book recommendations and take a look on YouTube for the 3D printer calibration advice mentioned. I tried printing some wood clamping guides but they weren't sufficiently square, although I have successfully printed various spare parts that were easily up to the job. Most of my tools were bought with the intention of using them to repair things, in many different fields, but that’s what you get with war generation parents!

It would be good if I could print more accurately, as I’d like to try printing a 127t gear, as mine is rather noisy (or something in that area is).

I got a good price on my lathe, partly because the gears were quite noisy. I can see some wear where one gear has worn the surface of the lathe body and the previous owner thought perhaps it “needed new pins”, although I haven’t looked into that as yet.

[Howard LewisParticipant @howardlewis46836]

The gears may be noisy if the backlash is either non existent , or too great. No, or negative backlash is BAD. It will cause wear of the gears, and load the bearings needlessly.

I set backlash by running a piece of paper, (about 0.003" thick (0.075 mm for the Metrical  ) through each mesh.

If the Banjo rotates about the Leadscrew, I start by setting the backlash between Leadscrew gear and the Idler, and then swing the Banjo upwards to set the backlash between Idler and Driver gear

If there are two Idlers, both are on the banjo, so their backlash is set before that of the Driver / 1st Idler mesh.

Heavy grease, (or Motorcylce chain lubricant ) is a good method of lubricating gears as well as quietening them.

Howard  (Smileys !!!!!!!!!!!!!! )

Edited By Howard Lewis on 20/03/2021 16:57:16

[Green TechieParticipant @greentechie]

Thanks Howard, I'll give that a try.

I've got white lithium, lithium moly, LM and CL grease, but I don't think I have any "heavy" grease. Fortunately, although I sold my bike, I still have a couple of spray cans of sticky chain lube.

I also have some 80gsm copier paper, which seems to be 0.08mm thick.

It will be interesting to see what sort of improvement I can make!

By the way, I assume the "pins" what the gears are mounted on? So I take it that the previous owner was thinking that the lateral movement of the gears may have increased due to wearing of the shaft (for want of a better technical term).

[Howard LewisParticipant @howardlewis46836]

Don't know the Kerry lathe. It is possible that itcompounds gears by means of pins rather than keys.

Normally the "axles" on which Changewheels are mounted are referred to as "Studs".

On the Myford ML1,2, 3 and 4, the gears were driven by driving collars, and compounded, by 3/32 pins between them, rather than the keys used on the later ML7.

The Driving Collars were clamped to the Mandrel, and the Leadscrew, by 1/4 BSF grubscrews, and the pin engaged in a matching hole in the gear. .

To enable a Series 7 gear to be used on a ML4; using another gear as a guide, I drilled a hole for the pin, away from the keyway.

HTH

Howard

[Green TechieParticipant @greentechie]

Well I'm confused now! I had assumed that the "pins" were the "studs". Now having looked for more information on pins and found a photo of some Drummond change gears, which have more obvious pins, I have no idea what the previous owner may have been referring to. The information was relayed to me second hand, as I bought the Kerry from Home and Workshop Machinery, but I don't recall seeing anything on the my lathe which looks like the pins on the Drummond gears. The plot thickens …

[Michael GilliganParticipant @michaelgilligan61133]

Some useful photos of the Kerry change-wheels on this page: **LINK**

http://www.lathes.co.uk/kerry/

… unfortunately for this discussion, they are in-situ.

MichaelG.

[Green TechieParticipant @greentechie]

Hi Michael, thanks for the link. I have looked at their pictures, as the lathe shown has the 60t imperial gear, which I lack. Unfortunately, as you say, much of the detail is hidden. I have taken mine (partially) apart and have seen no pins, so far. This is what mine look like.

[Michael GilliganParticipant @michaelgilligan61133]

I think we can now safely assume that the aforementioned ‘pins’ are Howard’s ‘Studs’.

… and there does look to be some considerable clearance on the one in your final photo.

We had one of those Kerry’s in the lab workshop when I was at BAe … and I always admired it.

The angled hand-wheel on the tailstock is a particular delight.

MichaelG.

[Howard LewisParticipant @howardlewis46836]

Is that a key way visible at the 11 o'clock position in the picture of the large and small gear?

Separating the two gears may answer the question. You will then know the size of any keyway, and the key or pin to fit.

It is possible that that the drive from Mandrel to Drive gear, and from Gear to Leadscrew could be via one or more pins set into the shaft, at right angles to the axis, i e radial?

If gears in the train are compounded, they would need to be on a sleeve with pins, which was able to rotate on the stud(s ). This implies that the sleeve would need to be reasonably thick to carry the pins to run on a stud with a smaller diameter than the bore of the gear.

If the gear is being used purely as a simple Idler, the need to key does not arise, but a spacer will be required to maintain alignment of the gear teeth, possibly with another spacer on the Leadscrew, for the same reason.

With a machine sophisticated enough to have a Norton box, I would have expected to find keys rather than pins to drive or compound the changewheels, since the shear load would be spread over a greater length. .

Howard

[Green TechieParticipant @greentechie]

Michael: It's good to hear you had a favourable opinion of the Kerry. I have little experience of other lathes, my previous one was a tiny "Super Adept", which I inherited. The build quality of the Kerry seems amazing to me. I feel like the proud owner of a high quality vintage car! There doesn't seem to be any play in gears in the photo and I wonder if the apparent gap is due to a bevel edge.

Howard: Yes, that's a 1/4" keyway. I have taken some more photos and uploaded them to the same album. I don't know if they are sufficient to confirm or alter your hypothesis regarding the gears. There is a spacer used in the gears previously shown, as is more obvious in the photo below.

[Howard LewisParticipant @howardlewis46836]

So, if you buy the two or three gears that you need, you may well have to widen or cut the key ways.

Ideally the new gears will be without a key way.

Hope that what follows is not teaching granny to suck eggs.

Having bored the gear hub to the correct diameter for your lathe:

Turn up a sacrificial bung, which is a snug fit in the bore of the gear.

On the boundary between the gear and the bung, centre pop, centre drill, and open up to 1/4" (or if cautious, to 6 mm ) diameter.

Remove the bung – it can be reused for the other gears, by drilling in another position.

The new gear now has a semi circular slot 1/4" wide and 1/8" deep, through the bore.

File away the surplus material to change from round to rectangular. (The keyway needs to be only half the depth of the key ) The key can be used as a gauge for the width, and then with one of the studs, for the depth in the gear.

Repeat for the other gears, and you should be ready for cutting whatever thread of which the lathe is capable.

HTH

Howard.

[Green TechieParticipant @greentechie]

Hi Howard, no danger of unnecessary egg sucking advice in this case! Part of my job for the last 30 years has been IT tech support, so I'm aware of how hard it is to pitch advice and don't get easily offended when on the receiving end. Even when it is a familiar subject … which this isn't. So any advice is gratefully received. I look forward to having a full set of gears, partly as I would like to make the lathe "complete" again.

Did you see anything obvious in today's photos to suggest problems, or did it look OK? Perhaps it's impossible to judge without physical inspection. I don't know how obvious problematic wear is, but I read in a different thread about a Kerry lathe (I think on this forum) that someone was very suspicious of any lathe where the gear train was at all noisy.

[Howard LewisParticipant @howardlewis46836]

Looking at the album, it looks as if the gears are compounded by the 1/4" keys, which also fit into a keyway on the bush. The oil nipples on the ends of the studs will then provide lubrication for the bush where it rides on the stud.

The bushes with keyways, to carry the gears obviously mean that the bore of the gears has to be larger than if the gear merely rode direct on the stud.

To one side of one picture is the lever and detents for the tumbler reverse, but the tumbler gears are not immediately visible.. There should be two equal sized gears, meshed together, and carried on the inner end of that lever, to enable the direction of rotation of the Leadscrew to be reversed, Probably with a centre position where neither tumbler gear is in mesh with the gear on the Mandrel.

PS Spur gears are rarely quiet, (Listen to a Bedford OB coach, or an Austin K4  in the lower gears! )

 Helical gears were introduced to make gear trains quieter. "Silent" gears was a selling point on motor cars in the late 20s and 30s.

Howard  Fat fingers again!

Edited By Howard Lewis on 23/03/2021 01:58:12

Edited By Howard Lewis on 23/03/2021 01:59:10

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Green Techie on 21/03/2021 14:21:23:

[…]

The build quality of the Kerry seems amazing to me. I feel like the proud owner of a high quality vintage car! There doesn't seem to be any play in gears in the photo and I wonder if the apparent gap is due to a bevel edge.

 

.

I think that’s a very good analogy

… and I’m delighted to accept that a bevel edge confused the eye !

[ I was simply trying to rationalise the previous owner’s remark about worn ‘pins’ ]

MichaelG.

.

Edited By Michael Gilligan on 23/03/2021 07:12:08

[SillyOldDufferModerator @sillyoldduffer]

Posted by Green Techie on 21/03/2021 14:21:23:

… I have little experience of other lathes, my previous one was a tiny "Super Adept", which I inherited. The build quality of the Kerry seems amazing to me. I feel like the proud owner of a high quality vintage car!

…

Big jump from a Super Adept to a Kerry!

No need for feel like one, you are the proud owner of a high quality vintage lathe! It was made at good time too: post-war lathes of that type were much needed by industry and it's modern design – made to work hard, quickly, and with precision. New machines like the Kerry were never in amateur ownership because they were off-the-scale expensive, roughly equivalent to paying cash for a couple of Bentleys when most people caught the bus.

Is it in reasonable condition though? The high cost of spares is the main risk of owning pre-loved expensive machinery. Whilst second-hand machines are amazingly cheap compared with what they cost new, the same can't be said of spare parts. They are often heart-attack expensive! Not unknown for a replacement headstock bearing to cost more than was paid for the whole lathe. Apart from that, lathes of this type are about as good as it gets, whereas the Super Adept is in the affordable home-workshop class.

Will you let us know how you get on with it? Buying a second-hand lathe of this type was high-risk up to about 30 years ago because they were mostly hammered and only sold when 'Beyond Economic Repair'. In recent decades machines like this were largely displaced from training establishments and factory floors as industry switched to CNC. Often kept in a corner for twenty years for odd-jobs, or little used in a College because teaching moved away from manual techniques, and finally sold cheaply on a falling market to make room, not because they're worn out. For us, absolute bargains, especially now 3-phase is so easy to arrange with a VFD.

Dave

[Green TechieParticipant @greentechie]

Thanks again Howard. I can confirm the tumbler arrangement is as you suggest. I take it nothing looked obviously worn then? Not that I can spot anything.

Thank you for the reassurance that some noise may be normal. I've not heard another similar lathe to compare it to and the only examples I could find of a Kerry AG running on YouTube seemed to have a reasonably quite gear train, but it was hard to judge accurately.

The gear noise as such does not really bother me. My concern would be if a noise suggested that damage was being done. Hence I would want to fix/replace anything worn that might damage other components due to uncontrolled movement.

Michael: Glad you approve of the analogy. I am still puzzled as to what the “pins” comment may have concerned. I have not yet found anything crying out to be replaced and I can’t help wondering if I am missing something!

[Green TechieParticipant @greentechie]

Hi Dave, your comment came in just as I hit "post" on mine. Yes, a big jump indeed, the Super Adept would sit nicely on the compound slide of the Kerry!

That's a very interesting historical insight and really puts things in perspective, thank you. As to the condition of the lathe I can't yet say (hence my request for comments on my photos of the gears). It "seems" in reasonable/good condition, but I am not qualified to judge. I have already discovered that parts are expensive! Having paid less for the lathe than some of the Chinese machines I was looking at I quickly exceeded my initial outlay on purchasing a 9" 4 jaw chuck, fixed steady and a collet set.

I have a 750W 4-pole three phase motor and inverter, which I was using with the Super Adept, knowing it was total overkill and intending to fit it to a later, larger lathe. It looks like it should be possible to fit it to the Kerry, which would give me variable speed in the different gear ranges.

Any suggestions as to things to check/look for to judge the condition of the Kerry would be appreciated. I'll post a couple of photos of the overall condition. I don't know if it's a good sign, but the front plate which shows the threading settings in still fully legible, whereas others I have seen pictured are often polished smooth (as it appears is Steve's at the start of this thread).

[Green TechieParticipant @greentechie]

One other thing I would welcome advice on, or suggestions on websites or other resources which give advice is how to care for the lathe and not damage it.

I purchased the "full set" of documentation for the AG from lathes.co.uk but there is not a lot to guide me on looking after the lathe. Certainly no diagram with arrows saying "oil all these places". It does make it clear to use oil, not grease. I assume the lack of "idiot instructions" is because anyone using one of these machines would have known what to do. Like Dave said, these would have been used by skilled people.

I found this page on Leeds Hack Space: **LINK**

… with advice on using their Kerry AG. They are using "50 SAE yellow metal safe" oil. They also give some guidance on oiling.

They also say "When using the lathe in 1500 rpm speeds on the left hand tumbler only power feeds E, F and G only should be used in order to protect the gearbox. With the left hand tumbler in positions A or B the spindle RPM must not exceed 36rpm." – this would not have been obvious to me and I want to avoid causing accidental damage!

[Green TechieParticipant @greentechie]

I've uploaded some photos from the original ad, which described the lathe as having "noisy screw cutting but probably an easy fix!". They are all in a new public album.

[Green TechieParticipant @greentechie]

Thinking about what Dave said about whether the lathe is in "reasonable condition" I have uploaded a few photos of the ways to my "Kerry AG" album, in case that might be any sort of guide to the lathe's past history. There are many, mostly small, marks but I don't know what is typical for a lathe of this age. So perhaps these marks indicate training or educational use by inexperienced users, or are they signs of heavy industrial use?

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