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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: Cross slide graduations?
29/08/2021 09:25:20

The OP said 100 graduations, so with a 5 mm pitch Leadscrew, each division would correspond to 0.050 mm, or about 0.002" in old money. To my mind, this suggests that each graduation would mean 0.05 mm off the diameter .

Howard

Thread: Coolant pump - how to slow flow rate?
29/08/2021 09:18:04

Why not rig up a by pass with a valve in it?

As the by pass valve is opened, the flow from the nozzle will decrease.

That's what is used on models locos with axle pumps and traction engines.

Howard

Thread: Type 2 precision vice from Arc euro
29/08/2021 09:08:38

Pete,

From memory, (Can't find the article! ) the auto cross feed takes its drive from a longer grubscrew on the ram.

For an increment of 0.001" the wheel would need 100T. It could probably be made by gashing with a slitting saw. To keep things to a reasonable size, even a gash 0.0625" wide would mean a wheel nearly 4" diameter!

So may need to settle for a minimum feed of 0.002"/stroke, to bring the wheel to a sensible size. But that still leaves the pawl teeth vulnerable at only 0.0625, although they don't need to be particularly deep.

IF only I could find the article!

Howard

Thread: Cross slide graduations?
29/08/2021 08:13:31

If you have a four jaw chuck, you are going to need a DTI, and a magnetic base.

Preferably both Plunger and Finger types, with graduations in which ever system of units your machine uses.

Until you do get these things, load a piece of bar and take a skim off it,

Do NOT withdraw the tool!

Measure the diameter. in Metric and Imperial units

Set the Cross Slide dial to zero.

Advance the Cross Slide by one division and take a cut.

Remeasure.

The difference should tell you what the divisions on the dial are. (As you say you should have removed the equivalent of two divisions, if the dial is graduated for radius, or if diameter that is what your measurements will show.

Howard

Thread: Hanson Steel Buildings
27/08/2021 18:35:54

Definitely insulate! Minimises risk of condensation and the rust fairy taking up residence.

Keeps it much more snug in the winter, and cooler in summer heat..

But do build in some ventilation, with a small inlet high up and an equally small outlet, at floor level, preferably diagonally opposite, to allow the slight air flow to ventilate as great an area as possible. The vents need some form of mesh across them to prevent spiders and other insect life coming in.

Unless the exhaust is ducted to the outside, don'tb use combustion heaters of any sort, only electrical heat. With good insulation in roof and walls, and floor if possible, the heater will soon warm the place up and only cut in for short periods.

HTH

Howard

Thread: Mill vise and rotary table
27/08/2021 18:20:20

Unless the vice is keyed to the table, replacing it will bring the problems of realigning it.

To avoid spending ages tapping (knocking ) it and winding to and fro with a clock, it will be worth making up some form of alignment jig.

My goalpost fixture may cause mirth, but it sets the vice within 0.001" in less than 5 minutes, instead of 20 minutes of clocking and frustration.

(As an Apprentice spent many unhappy times trying get a 6 or 8 inch Abwood vice that close! )

Howard

Thread: Manual/ book
27/08/2021 18:10:06

it is possible that the same machine was imported by other suppliers under a different name / number.

i.e the Rong Fu RF 20 and RF 25 were imported to UK by more than one supplier,

PCD 30 suggest that it might be something akin to a RF 30 which was possibly known in UK as a "Major" or some similar name.

Any other number available from the data plate, such as manufacturer? Even spindle speeds, and belt positions, may help.

Pictures would help.

So it may be possible that an Operator Manual for one importer's machine may well be what you are seeking.

If you can run the machine to earth, a manual or a photocopy might be made available to you by someone on here..

Howard

Thread: A SIMPLE POINT !
27/08/2021 17:58:05

Being trained in UK, I was taught:

Bolt - Threaded upto a plain shank beneath the square or hexagon head

Setscrew - Threaded all the way to the head

Machine screw - Tightened by a screwdriver of some type.

Capscrew - Tightened with an Allen key..

Coachbolt - Dome headed bolt or setscrew with square under the head.

Coach screw - Square or hexagon headed screw, with tapered coarse thread, to go into wood.

Howard

Thread: 1st time thread cutting
26/08/2021 17:42:40

As a means of peace of mind, before cutting metal, it would be worth checking that rotating the chuck by hand for 1 or even 10 revolutions moves the Saddle by 1.5 mm or 15 mm.

Once you are happy withe set up, then you can cut metal.

My first attempt at thread cutting was a 1 mm pitch for the lens panel on a plate camera, done with much fear and trembling. At least if it had gone wrong, it would only have meant throwing away some Aluminium sheet, rather than hours of work on something more complex!

Once you succeed, you will have the confidence to do more in the future!

Howard

Thread: Interfering with fits?
26/08/2021 09:17:27

Looking back through some old M E s came across a formula to aid arriving at the correct interference.

A = (1.00625 D) + 0.5 where A is the interference in Thous, and D is in inches.

Presumably A would be microns, and D would be mm if working in Metric units.

Seems a bit large to me, being overcautious.

0.001" on 1.000" steel into cast iron seems to work OK for me, so maybe 1/1000 on diameter might be an adequate rule of thumb..

Anyone like to confirm?

Howard

Thread: Is there such a thing as an 'external reamer'?
26/08/2021 09:02:32

If the stock is large diameter, parting off in the lathe will save your muscles, although wastes more material.

If it needs to be said, ensure that the Tailstock is properly aligned before using a cutter in the Tailstock, to minimise the risk of cutting oversize on OD, and undersize on ID..

Howard

Thread: Hello from the west country
26/08/2021 08:57:30

Welcome!

LOTS of experience on here in all sorts of fields.

You won't be the only Colchester user, by a long way. Search for posts about Colchesters, there should be several.

Just like me, not touching a machine tool after the Training School, until YEARS later, "Can you come in and show the nightshift" The partially sighted leading the blind, or maybe the other way round!

Howard

Thread: Type 2 precision vice from Arc euro
26/08/2021 08:44:54

Note the warning not to disengage the Allen Clamp screw, because of the difficulty of re-engaging it!

The screw is slackened far enough to allow the bar to disengage from the semi-circular "rack", to allow the jaw to be moved along the base, before being re-engaged and the screw tightened to pull the moving jaw forwards and downwards to clamp the workpiece.

As an aside, I graduated the dials on my No.2. The Cross Slide was straightforward with 100 divisions of a thou. for the 10 tpi Leadscrew.

The downfeed Leadscrew is 16 tpi, so that dial has 62 full divisions and a small one for the final 0.0005"!

Somewhere there there is a system for an automatic feed for the cross Slide. One day, I'll get round to making and fitting it!

Howard

Thread: Mill vise and rotary table
25/08/2021 12:35:24

I rarely have two devices on the table at the same time (Rotary Table, or tilting vice ) because of the risk work in one obstructing, or being obstructed by the other.

So, most of the time the K4 vice sits centrally on the table, occasionally being displaced by the Rotary table of the "Infinite" vice.

Howard

Thread: Interfering with fits?
24/08/2021 14:35:47

An alternative to cutting a key way would be to mount the "Wheel" onto the shaft with as close a fit as possible, and then to drill and tap two diametrically opposed holes on the interface between the parts, and screw in grubscrews to act as "dutch" keys. Grubscrew length, ideally should match the thickness of the "Wheel"

For good measure, use Loctite or a similar anaerobic locking agent on the dutch key grubscrews so that they are unlikely to come looses.

Howard

Thread: Jammed shaft key removal
24/08/2021 14:27:10

Making Woodruff keys?

Depends how urgently you want to be up and running again!

Things usually fail just after the supplier shuts on Saturday, so you are stopped until probably the middle of next week! The same way that the Tap breaks in the last hole!

Howard

Thread: Myford super 7 with gearbox - leadscrew stopped turning
24/08/2021 14:22:07

As P S7 advices, start checking from the start of the drive, and work your way through until you find the part that no longer rotates. The problem lies with the previous part of the drive train., probably a missing tooth, loose grubscrew or sheared key.

Ensuring that gears have the correct backllsash is important. Too little = noise and wear; Too much wear, inaccuracy and damaged teeth.

howard.

Thread: Hello from Marlborough
24/08/2021 14:15:25

Welcome!

If you are new to machining and engineering in general, you can get lots of advice on here.

But if a first time lathe user, it would be worth buying and reading some books.

First purchase Zeus Charts - a useful reference pocket book.

"The Amateurs Workshop" by Ian Bradley. Good advice on workshop techniques as well as lathes.

"The Amateurs Lathe" by L H Sparey - Written when the Myford ML7 was the amateurs's most likely machine of choice.

Harold Hall (former MEW Editor) and Neil Wyatt (Current M E W Editor ) have both written books on lathework

"The Model Engineer's Handbook" by Tubal Cain is an invaluable reference book..

For more specific subjects, such as Taps and Dies, Screrwcutting, or Gear cutting, and MANY more, there are the WorkShop Practice series.

All these will provide answers to the question that will arise.

For face to face advice, guidance, perhaps demonstrations, find and join a local Model Engineering Club,

Begin learning by just cutting bits of metal, then making small accessories and tools for the lathe and workshop.

(Centre Height Gauge, Mandrel Handle etc. )

You would probably be better to start by using HSS tooling, which will mean buying a Bench Grinder if you don't already have one. In this way you will learn how tools need to be ground. HSS tolerates the odd knock better than Carbide, and a toolbit which can be reground many times costs about the same as one carbide tip!

(Probably my most used turning tool is a Tangential Turing Tool. The toolbit is easy to grind, with a small jig, Just one face. Such a tool can be shop made, or purchased - The Diamond Tool is the usual commercial one )

When you have gained experience and confidence you can progress to more complex things.

Better to make mistakes and learn from them on a bit of steel bar than an expensive casting!

HTH

Howard

Thread: Is there a Gitzo tripod expert in the house ?
24/08/2021 13:55:36

You could carry one of those rubber strap tools with you. Intended to unscrew bottle tops It is a small strap wrench

It is called a "Boa Constrictor" A rubber strap attached to a short plastic handle, with a slot into which the excess strap fits.

Lightweight and very effective.

Howard.

Thread: Interfering with fits?
22/08/2021 13:13:19

The sacrificial plug does not have to be Aluminium. It would be better if it was, to lessen the risk of the drill wandering.

The object of drilling is to remove as much metal from what is going to be the keyway, leaving less for the keyway cutting tool to remove.

FWIW, having drilled the hole, when you start to cut the keyway, don't be greedy, better to succeed after lots of 0.005" cuts rather than trying a few 0.050" cuts and failing and possibly damaging tool, set up and workpiece.

A tool 4 mm wide / deep won't be strong, so small cuts have to the order of the day.

Once, I produced a 1/8" square, blind, hole in brass, by drilling a 1/8" hole and then forcing a 1/8" toolbit in for 0.010", withdraw, rotate chuck 90 degrees repeat, and then repeating and repeating until I had the square hole of the depth that was required.

Slow? Yes, but it produced what was required (An extension for a speedometer cable )

I would be thinking in terms of the workpiece in the chuck, and a 4 mm toolbit, mounted in the toolpost, equally about the lathe centreline, with the cut ( 0.050 mm? ) being gradually applied by moving the Cross Slide and racking the Saddle too and fro.

I made a Peter Robinson Slotting Tool, and adapted it to my larger lathe , and have used that to cut keyways quite successfully. But am unsure if College Engineering Supplies still sell the casting.

Howard

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