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Member postings for Howard Lewis

Here is a list of all the postings Howard Lewis has made in our forums. Click on a thread name to jump to the thread.

Thread: Emco Compact 5 - complete newbie
30/05/2022 13:55:38

Welcome to the Forum.

Lots of books on general use of a lathe.

L H Sp[arey, "the Amateurs Lathe"

Ian Bradley "The Amateurs Workshop" is more general workshop, but is still good on a lathe.

Harold Hall "Lathewoek"

Dave Fenner, David Clark and Neil Wyatt have all written books, about the mini lathe., rather than the EMCO, but the basic principles are the same. The difference will be in the specifics of what is located where and what does what.

Any lathe will obey the same laws, needing a sharp tool set at centre height, and fed at the correct speeds and fed rates for the material being worked.

If you are a complete newbie, become familiar with the lathe and how to use it by making small tools and accessories, before launching into anything expensive. The tools (Centre Height Gauge, Tap Wrenches, etc ) that you make will allow you to learn the basics, and will be useful for years in the future.

There are some very knowledgeable EMCO users on here.

HTH

Howard

 

Edited By Howard Lewis on 30/05/2022 13:59:06

Thread: chips from cast iron abrasive ?
30/05/2022 13:41:11

Washing hands in any sink after machining cast iron will give i the "measles" look. And it takes some work to remove the stains! Possibly a justification for a separate plastic bowl, maybe even oit of doors if the weather is good enough!

Howard

Thread: Ml7 just bought, need help to set up
30/05/2022 13:32:09

By all means buy and read L H Sparey, but also get Ian Bradley's "The Amateurs Workshop" or his "Myford Series 7 Manual". Both these books give the instructions for taking the twist out of the bed, to minimise the risk of not turning parallel. (Sparey does not, unfortunately )

Once that has been done, the Tailstock should be aligned, so that unless a taper is deliberately required, work turned between centres should be parallel.

Howard

Thread: Beginner
30/05/2022 12:53:17

As others have said, buy some books on using a lathe .

Harold Hall, Ian Bradley. (The Amateur's Workshop, and the Myford 7 Series Manual ), Stan Bray, and L H Sparey (The Amateurs Lathe).

Books on the mini lathe have been written by Dave Fenner, David Clark and Neil Wyatt.

Neil also wrote a series on using the Sieg SC4 in Model Engineers Workshop, some time ago.

You do not have to have all of them, but more than one may cover some feature or technique not mentioned in the other(s )

Whilst some of the books deal with a specific machine, others do not. Every one will contain information on the basic principles, which can be applied to almost any lathe..

The advice to learn using the machine by making small items is good. Not only will you learn, (From mistakes as well as successes ) but you will have a small collection of tools that will be useful in the future. You start with simple, straightforward ones, and as you gain experience and confidence, progress to more complex items.

Possible items could be

A Centre Height Gauge,

one or two Tap Wrenches of different sizes,

Stud boxes for various types and sizes of threads

An Alignment Bar for when you want to check or adjust the alignment of the lathe, to remove twist from the bed, or to align the Tailstock

(Ian Bradley's books will tell you how to check and adjust the lathe to take twist out of the bed. A lathe with a twisted bed will be unlikely to turn parallel.

A second Centre, for when you want to centre work in an independent 4 Jaw Chuck

A Tailstock Sliding Die holder, (You can buy the Arbor and actual Die holders, just make the basic body )

More adventurously, a Tailstock Sliding Tap Holder ( Mine uses ER 25 collets )

A Mandrel Handle (useful when using Dies nor Taps in the lathe, especially when working up to a shoulder )

To make these items, you will need measuring equipment, probably a calliper (Digital, Dial, or Vernier ) to begin, or a selection of Micrometers.

With a 4 jaw chuck you will need a magnetic base and at least one dial indicator. Often ntwo can be have their muses, a Plunger type and "Finger" clock, ( usually more sensitive, and can be used in a bore where a plunger clock cannot go )

You can make these tools as simple , or as complicated / decorative,as you wish as you progress.

In the future, you will ,find a use for all of these things, sometimes often, others less frequently, but still useful.

It is better to make mistakes (And even scrap a job ) in a piece of mild steel bar than an expensive casting from a kit.

Books like G H Thomas' "The Model Engineers Workshop Manual" and "Workshop Techniques" will give you ideas and provide drawings.

One final sombre note, THINK SAFETY., and be careful You don't have to go overboard, but just take care.

(Turn the chuck by hand to ensure that everything is clear before applying power. )

Don't leave a chuck key in the chuck, except when you are using it to tighten or loosen the grip..

Even a small lathe is likely win if you get entangled with it

And beware of sharp edges on workpieces or swarf

Howard.

Thread: Getting old, selling lathe
28/05/2022 14:55:26

Hi David!

Sorry to hear the news of another loss to our hobby.

Very small consolation, but you are not alone in feeling the effects of age. It's bad enough getting down to pick up something dropped on the floor, but getting up is an even worse matter!

Hope that all goes well foe you.

At least you can keep in touch via the Forum.

Howard

Thread: Again - another whatsit
28/05/2022 10:35:52

If it is COMPAQ, it is expensive, and valuable!

Not long ago, I wanted to replace two extensions and an anvil for a Compaq bore gauge.

Spares were not available (Retained for repairs ) but I could buy a complete new on for upwards of $5,000 with a lead time of 6 months!

For my use, I bought a 5 x 0.5 Tap and Die and made my own. Since it is set up and Zeroed against something like a micrometer or slips, a small error will not be noticed..

Take care of it, it is high precision!

Howard

Thread: Scaping bearings
28/05/2022 10:25:27

Don't worry, Ivy

We all learn as we go along, every day.

Experience allows us to recognise the mistake, the next time that we make it!

With a low speed, drip fed, fairly lightly loaded application you can afford to minimise clearances.

When Sentinel made expansion engines for British Oxygen, the large whitemetal bearings used to be hand scraped. Being a big, single cylinder engine, the pile of swarf on the floor was big!

For accuracy you need the spindle to be kept as closely aligned as possible anyway.

Howard

Edited By Howard Lewis on 28/05/2022 10:28:40

Thread: Finnish on Test Piece
28/05/2022 10:17:25

Double post

 

Edited By Howard Lewis on 28/05/2022 10:19:58

28/05/2022 10:14:11

Dave is absolutely right.

If it ain't broke don't start fixing it!

With insufficient skill, knowledge and equipment, stripping a machine may change it from a reasonably precise item into something which is less accurate than when you started.

A friend bought an elderly lathe which had been stripped and "improved" by a previous owner. It would not cut parallel because a cross threaded stud was pulling the Headstock out of line. We had to bush the tapped hole so that the machine aligned correctly, and no longer cut an unwanted taper.

Older British and American machines will have been made to Imperial dimensions, and most of the threads will be Imperial, rather than Metric

Surprisingly, to me at any rate, not everyone realises the need for the tool to be mounted at centre height, and to have correct clearances.

Too low, there will be excessive front clearance.

Too high and the cutting edge will not be able to do much cutting, instead it will rub, generating heat but little or no swarf.

To prevent rubbing,a tool needs, for most purposes, to have front, and side clearances of about 5 - 10 degrees, and something similar for top rake. For soft materials, like brass, it is sometimes better to have no top rake, to minimise risk of dig ins.

For many years I have used my parting tool with no top rake, just side and front clearance, for this reason.

Excessive clearances weaken the cutting edge, and shorten tool life because of the lack of material to conduct heat away from the edge

A blunt or incorrectly ground tool will not cut well.. (A badly ground drill, if it cuts, will produce oversize holes. )

For some materials, usually tougher, or the more exotic, clearances have to be more specific to optimise the cut and finish. Ditto for speeds and feeds..

To machine mild steel, think in terms of 100 fpm (30 Mpm ), for a good finish feed should be about 0.004" /rev (0.1 mm/ rev )

No doubt others will disagree with some of this.

HSS steel will not cut hardened steel. For this carbide tools are needed

If there is slack in the bearings, or gibs or the chuck jaws are worh (Usually bell mouthed ) you will have difficulty in getting a good finish or accuracy. Similarly, tools need to be held as rigidly as possible, with minimal overhang from a solid, rigid toolpost.

As with measurements, rigidity is important. A light machine, under cutting loads, will deflect more than a heavy rigid one.. Which is why, light weight hobby machines cannot withstand operating at the speeds, feeds, and depths of cut of the very much more costly industrial ones.

Howard

Thread: Just Joined
28/05/2022 09:29:18

Hi MIke,

I find a set of parallels very useful to pack work in the vice, (Upwards and / or longitudinally ) for milling.

Howard

Thread: MES Kennet Tool and Cutter Grinder
28/05/2022 09:24:07

For my Worden, like Giles Parkes, I made up a holder for ER25 collets. These enable me to grind End Mills and Slot Drills; and allied to the 31 degree wedge for the "standard" drill grinding attachment, four facet ground drills,

ER collets allow Imperial, Metric, Letter or Number drills to be held with the minimum of holders, ( 13 rather than over a hundred needed to make a specific holder for every size, as the Hemingway basic instruction suggested )

The clamp nut required some machining of both front and back faces, at suitable angles, with a carbide tool, to maximise clearances between wheel and table.

With the drill inclined at 31 degrees, the end angle will be ground to 18 degrees, ( 118 / 2 = 59. 90 - 59 = 31 ) and the secondary and primary clearances are obtained by swinging the holder about its pivot point.

Howard

Thread: Scaping bearings
28/05/2022 09:04:07

The surface finish of the shaft is important. A rough finish will allow oil to drain away, allowing metal to metal contact, leading to failure.

In automotive engines with pressure oil feed, the steel backed shell beatings, of various compositions, (Aluminium/Tin, Aluminium/Silicon etc ) with normal clearances, the shaft needs to be dimensionally correct to within 0.001" ( 0.025 mm) on diameter and have a primary surface finish of no more than 16 micro inch Centre Line Average.

At 18 CLA, the shell will begin to show a polish

At 20 CLA the bearing will begin to wipe (Localised melting ).

By 22 CLA failure is certain!

With Nitrided, or Tufftrided shafts, rather than Induction hardened, these limits become even more important.

Once failure begins, "healing" is MOST unlikely, usually the damage increases exponentionally. Often the root cause is impossible to find, because the damage to shaft, bearing, and housing is so extensive. Often the steel shell, if any is left, will have been blued and hammered to a thickness of less than 0.001" The whilte metal will have been distributed by the pressurised oil all over the surroundings, in minute flakes..

The "White Metal" bearing needs to be of similar finish, a variation of 0.00001" (0.00025 mm 0.25 microns! ) will show itself as a polished band on the surface of the bearing surface. More than that leads to failure..

This kind of failure can happen at speeds of 2,000 rpm or below, with rubbing speeds of as low as 1,500 f p m..

So shaft and bearing finish and clearances need to be correct to minimise the risk of wear or failure.

Howard

Thread: Just Joined
27/05/2022 18:55:20

Welcome!

Looks like you are progressing well.

Keep it coming!

Howard

Thread: Key for a Cowells lathe chuck
27/05/2022 18:49:29

If the "gears" match, turning down the "shaft" can be pretty simple.

Hope that this is not a Catch 22,, "Ttere's a hole in my bucket, Dear Liza" job!

Remove the lever arm, mount in the lathe (I used the 3 jaw to be quick and nasty ) and turn down the spigot to the required diameter and length.

Refit lever, and hopefully, all will be well.

In the past, for drill chucks, rather than a Cowells chuck, this has worked for me.

Howard

Thread: thanks for having me!
27/05/2022 18:36:32

Welcome to the Forum.

At the weekend, go to Broomy Hill in Hereford and meet the HSME.

They are a very very friendly bunch, so will be extremely helpful to you.

They are next door to The WaterWorks Museum. TOO infrequently, I make the long journey across country to do a days volunteering there. Again, the volunteers are a friendly bunch, but their machining is for necessity, rather than for a hobby.

Howard

Thread: New member
27/05/2022 18:19:04

Welcome!

If you are new to using a lathe, it might be better to practice on some steel to start with.

You can see the effect of grinding tools in different ways, and shapes, and learn about speeds and feeds before you make a mistake and scrap off an expensive casting.

It can be a useful learning exercise to make a few simple tools before launching into a costly kit of parts.

You will always find things like a Centre Height Gauge, Tap Wrench, Tailstock sliding Die holders, ditto Tap holders, Mandrel Handle, etc useful in years to come. And you will have gained useful experience in making them. (And if there is a false cut, or poor knurling, it may not look too good, but it will still do the job, and you will have learned from it. )

Howard

Thread: chips from cast iron abrasive ?
27/05/2022 17:57:43

The outer skin of a casting is often HARD (Cast iron camshafts often have chills in the mould, to chill and garden the nose of the cam )

We received a batch of cylinder block castings which ruined every cutter in the transfer line. (Once loaded, it was impossible to stop and extract them! The problem was that the foundry had knocked out the boxes near to where the cladding on the building had been removed, allowing snow to blow in onto the red hot castings, and chill them!

Even with dust extraction, a surprising amount of dust escapes.. Using greased plates, and weighing the dust collected, indicated that over the area of the shop machining that particular cylinder block, there was one, very finely divided, floating about in the air above!

So in the air above the machines, the powdered hard skin of cast iron can be very abrasive and damaging to the machine on which the work is being done..

When machining cast iron, I always put a powerful magnet under where the swarf will fall, and cover it with paper. Carefully removing the paper brings away a lot of the dust (Not all unfortunately ) Away from the magnetic field the swarf can be tipped into a suitable receptacle for disposal.

Makes cleaning up so much easier!

Howard

Thread: Milk container top colours
27/05/2022 17:41:15

Around East Anglia, the coloured tops are recycled separately, (By a different company in a different town, and even county! ) whereas the bottles go in the council recycling bin.

Howard

Thread: Scaping bearings
27/05/2022 17:35:29

Low speed drip fed bearings and high speed, pressure fed bearings is not am good comparison.

The IC engine bearings are fed with a copious supply of oil under pressure and easily build up a dynamic wedge of oil.

The headstock bearings of a Myford are drip fed and run at comparatively low speed, and are probably designed for much smaller clearances. (A high speed IC engine will be designed for circa 0.002 - 0.004" 0.05 - 0.1 mm clearance, to allow a good flow of oil, to provide cooling as well as lubrication).

The purpose of blueing and scraping will be to maximise the area riding on the dynamic wedge of oil; possibly boundary lubrication only a few molecules of oil thick.

A headstock with automotive clearances would be classed a badly worn machine tool..

Howard

Thread: Finnish on Test Piece
26/05/2022 19:15:44

It sounds as if OP is working tom take twist out of the bed, (As per Ian Bradley, and Myford's advice - "Rollie's dad's Method", so Tailstock support should not be used .

It may well be that the head bearings are slack, so that the tool is acting as an extra bearing close to the chuck

This assumes that the tool is sharp, and accurately set at centre height

The machine set up needs to be investigated and each error eliminated , to obtain a good finish.

The skill to provide a steady hand feed is one to learn.

Alternatively, the change wheels could be set up to provide the finest feed possible, about 0.004" per rev would be good target.

It will allow a better comparison of finish, since the feed per rev should then be be the same.

Howard..

The finish may improve if a very small radius is stoned on the edge of the tool. But ensure that the tool does not rub below the cutting edge...

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