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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: Cheap alternative to replacement Record hardened jaw plates?
09/06/2015 20:44:06

Can only agree with all the advocates for gauge plate, hardened or otherwise.

My experience of magnet retained Aluminium soft jaws is that they don't stay retained for very long. Then I hammered over the top and ends to retain them. They stay in place when gripping, but fall off as soon as the jaws are opened. NOT good for blood pressure or temper, but keeps the back supple picking the............things off the floor or bench!

Fibre jaws don't grip as well, and soon get mangled. I have a new boxed set on the shelf that I can never bring myself to use, for that reason!

Howard

Thread: Albion Gearbox 3 speed gearbox dismantling.
09/06/2015 20:30:03

If you turn up a mandrel so that the bore of the sprocket is a really snug fit, using tungsten carbide tip, (brazed or replaceable, you should be able to turn down the O D of the sprocket where the seal used to run.

Before you do this, decide what diameter you want to use, and Google "Speedisleeve". A Speedisleeve is stainless steel sleeve prepared as a track on which a rubber lipseal will run, with a built in "break off" groove near the flanged end.

So the diameter to which the sprocket is turned, based on the I D Speedisleeve that you choose to replicate the original seal diameter, pre wear).

The Speedisleeve comes with a fitting dolly, (you may wish to use Loctite, to make certain that it stays in place)

You tap the sleeve into place and then break off the flange against which the dolly seated. If you are worried about the rough edge, break the rough edge with a fine stone, or diamond hone, taking care not damage any of the seal running surface.

You then have a nice new, beautifully prepared, surface on which the new lipseal is to run.. AND it will provide a better, lower friction seal, (and probably last longer than the original felts). BUT, DO lubricate the sleeve before you bring it into contact with the seal.

This assumes that you can fit a lipseal instead of the felt seal. (You might need to turn up a housing and bolt it into place in place of the felt seal housing, unless you can find a suitably sized lipseal. If push comes to shove, you could turn up a sleeve with OD to match the felt housing, and the ID to suit the lipseal.

To insult your intelligence, the seal is fitted with the lip and garter spring facing towards the gearbox, so that you see the flat face of the seal after assembly.

If using a lipseal not possible, still use the sleeve to reclaim the seal diameter and fit new felt or ropeseal, but again, lubricate before fitting the sprocket and start up. If a ropeseal, soak in oil for 24 hours before fitting, and then burnish into position with a clean round bar.

Howard

Thread: EMG-12 Endmill Re-sharpening module
03/06/2015 22:15:08

Thanks to all who provided details of where to get End Mills sharpened.

Will follow up in the near future.

Howard

Thread: MEW Adhesives
31/05/2015 19:08:34

One of the reasons that adhesives are used, particularly in aircraft, is that the load is not concentrated as it would be with a bolt or rivet, but spread over a larger area, so reducing the level of stress.

Plastic mouldings have stresses "built" into them by virtue of the fact that the material is forced to flow through the mould. Over time these stresses relieve themselves. Temperature can hasten this. A plastic food box will soon distort if regularly washed in hot water, because the heat "encourages" the stress relieving.

Metal castings will stress relieve similarly (In the old days, castings were weathered for a couple of years before machining. Now, if stability is required, the castings are allowed to cool slowly, or reheated and slowly cooled, to stress relieve before machining).

I have used Loctite which was probably twenty years old. (WELL past its shelf life) Several years later, with the anaerobic having been applied over a fairly large area, the joint would NOT break!

So don't be too despondant!

Howard

Thread: Spot Welder
31/05/2015 18:55:49

"It's the Volts that jolts, but the Mils that kills"

Prewar TVs used a separate mains power supply for the EHT to the tube. VERY dangerous! I have had the odd belt from a CRT, but since these used flyback EHT, very little energy was available. (Ditto for OLD coil ignition systems on engines, BUT beware of the more modern ones. They do pack a dangerous punch).

The current available is driven by the voltage and resistance into which it is delivered, and by the power output of the supply. The TV was low power, but the same can't be said of a 400Mw Power station which ultimately feeds the mains. I have survived a 240 volt shock, fortunately standing on a 5Kv proof floor! If it had been a puddle, you might not have been bored by reading this.

In the Electronics and Vibration Lab we used to check our body resistance, every Monday with the AVO 7. If we were under the weather, with say, a cold, we read 120K instead of 140 - 150Kohms

A 12 volt car battery will not kill you, (Your body resistance of over 100K Ohms is high enough to limit the current to less than 1 MilliAmp), but WILL burn hole through a screwdriver, or lumps out of a spanner, because it can deliver 300 - 400 Amps when short circuited!

Treat Capacitors with similar respect. They can hold a high voltage charge for some time, and deliver, for a short time, a high current. Those Coulombs (Amps x Milliseconds) can be enough to kill!

An electronic flash for a camera can deliver 100 watt seconds of energy, in 1/1000 of second. The tube needs 500 volts to strike.so the current is about 200 MilliAmps, delivered in 1 Millisecond, or less. 200 Coulombs is LOT of energy into a human body. At worst, lethal, but if survivable certainly VERY unpleasant, and definitely non preferred.

Preferably, discharge the Capacitor with a high value resistor, say 1 Mohm, or more, to minimise the current, and as advised, wear rubber gloves and use insulated tools, in a dry location.

H T H

Howard

Thread: Aircraft General Discussion
31/05/2015 17:45:14

Reverting to the subject of Air Marshalls, back in the 80s Iran Air had them.

The Captain announced that we were flying at 36,000 ft, as we looked at two guys cradling their AK47s! One itchy finger and we would ALL have been flying at 36,000 feet, but not inside the aircraft!

On another occasion, we were told that RAF Marholm used to train Pilots and Navigators in aircraft equipped with ground following radar. The Flight Plan was recorded onto a cassette tape, which was then played back in the cockpit, to the control system. One of the later flights was for the whole squadron to fly, in a time interval line astern pattern, a LOW level figure of eight route to Scotland, crossing somewhere in Yorkshire, at night. Apparently everyone came back lighter and more moist than when they took off!

Howard

31/05/2015 17:18:48

At the risk of repeating what most know; apparently, the Eurofighter is designed to be unstable, to make it more maneuverable (NEVER could spell that word!) and is kept in the air by its computers which constantly avert disaster.

Based on my very limited experience of being flown in light aircraft, I would never have made a pilot. You seem to need eyes everywhere. The thought of having a jet fighter fly under me in a glider, or on finals, is terrifying.

Howard

Thread: EMG-12 Endmill Re-sharpening module
31/05/2015 17:05:50

It's very sad when a thread descends into abuse mode. That is NOT what the Forum is about in my view.

There is a lot of interesting info supplied, and name calling does no good at all, other than putting off people, especially newbies.

I respect Ketan for his open minded and honest comments on this thread, and others elsewhere. Yes, I am a customer, but he wouldn't live for a day on the profits from my purchases!

I would love to have an EMG12, or larger, but 1) lack the space to store it, 2) cannot justify such a purchase, which leads onto my questions.

Presumably John Stevenson has an EMG 12, as has Bog Standard 2.

QUESTION 1

Whereabouts in U K are you two gentlemen? (Probably a couple of hours drive away from me?)

QUESTION 2

Would you be prepared to sharpen End Mills for folk who brought them to you, (for a consideration)?

Obviously, this would have to be either, by appointment, or on a "leave/collect later" arrangement, so as not to interfere with the "day job".

You can see where I'm heading, (probably along with a lot of others).

Howard

Thread: The Manchester Model Engineering Exhibition
31/05/2015 16:01:15

Presumably, this is a resurrection of the Show that was held for a couple of years at the Event City , Trafford Park a few years ago.

In addition to the M.E. Shows already mentioned, there has been a Show at Spalding for the last two years, which appears to be growing. Great, since East Anglia seems to be missing out otherwise.

It's good to see the local, and sometimes, not so local, M.E. Clubs supporting Exhibitions by having stands there.

Lets hope that this one succeeds.

Howard

Thread: Bleeding Compressor
20/05/2015 18:59:51

When I bought my compressor, the advice given was to always drain after use, and to leave the drain valve open.

Despite this, when the compressor is moved, some water drains out. Draining with a full tank, usually results in a moisture cloud, followed by a stoppage. Eventually the ice melts (The air expands and cools and takes heat from it surroundings, reducing the temperature below freezing point - hence the ice) In the days when I worked for a large bus company, the large twin cylinder compressor in our depot would do the same when drained each week. It took so long to melt that we used to open the drain as we went for a cup of tea, so that it could drain/ice up/melt and continue draining while we took a break.

Howard

Thread: How many is too many?
20/05/2015 18:38:14

The Union Pacific 12 coupled loco. used conjugated valve gear with what looked like the Gresley/Holcroft design. The locos were numbered in the 9000 series.

I think that Russia made a 14 coupled loco, but could only be useful on straight track.

Lots of tractive effort, but locos with so many coupled wheels must have been barred from any track with a distinct curvature!

The British rail 10 coupled 9F s had flangeless centre driving wheels, and probably a lot of side float on the other axles. Not only could they pull, but could run at express passenger speeds when required! Possibly the last and best steam locos made in Britain.

The alternative was use an articulated loco like a Garrett or a Mallet, (although, strictly, Mallet were compounds). Some U S railroads, such as Union Pacific ( Big Boys and Challengers) used simple expansion articulated locos.

Garrets were simple expansion machines, with a large boiler articulated above the engine units, and came in 4, 6 or 8 coupled forms..

The Erie Railroad even had a Triplex, (The Matt H Shay) described as a Mallet, with an engine unit under the tender, as well,

On a smaller scale, the logging roads used two (or even three) truck Shays, others used Heisler or Climax locos to obtain sufficient traction on sharply curved track. poorly laid in the woods as a temporary measure. But these were mounted on two axled trucks, to use full weight for adhesion, and flexibility.

The Shay power unit was usually a three cylinder mounted on the right hand side of the loco, driving the trucks through longitudinal shafts and bevel gears. The Heisler had a V twin steam engine mounted under the boiler, driving each truck, again via longitudinal shafts and bevel gears. The Climax prototype was merely a steam engine and boiler mounted on a flat truck and driving via chains.

Howard

Edited By Howard Lewis on 20/05/2015 18:40:40

Thread: Pressing wheels on without a press
20/05/2015 17:45:06

Could you pull the wheels onto the shaft using a spreader -plate at each end and nuts on threaded rods to provide the force?

Would suggest at least three rods, M6 would be my favourite,with the nuts tightened AS EQUALLY AS POSSIBLE.

If the nuts show signs of stripping either make new nuts (for both ends) with 2 diameter thread engagement, and/or redrill to use more rods. Quite a force can be applied with a couple of M6 studs and nuts.

(My bearing extractor uses a 1/2 or 5/8 BSF thread to remove bearings which I know need about 4 or 5 tons to shift them)

Howard

Thread: Using a brick garage as a workshop
20/05/2015 17:11:06

I helped a friend insulate a concrete panel pitched roof garage as a workshop.

We merely patched the floor, to get it somewhere near level, before covering it with chipboard.

We insulated the walls with polystyrene sheets and covered that with a polythene sheet as a vapour barrier (DPC) (taking care to position the wiring where it would be safe from screws or nails), before fixing 6mm ply panels as the inner wall. The steel roof trusses got much the same treatment, except for the DPC and plywood panels.

So far, there seem to have been no problems with damp or rust, on the lathe, or materails. (He uses the one end to store some of his two wheeled machinery , none of them show any signs of distress several years on)

Howard

Thread: Adjustable Dials for Feedscrews
20/05/2015 16:57:40

A relatively crude method, (like most things that I do) was used on a Loughborough where the friction set up no longer functioned reliably.

First of all, made up a simple 3BA screw (Use Metric if you like, or any other convenient thread) with a knurled head. Then, having stripped out the Cross Slide leadscrew handle arrangement, just drilled and tapped a 3BA hole in a suitable position, relative to the dial and its graduations. Once deburred, everything was reassembled, with a thin brass plug under the screw, and the knurled screw was then used to lock the dial to the leadscrew.

To reset merely unscrew, reset the Zero, lock up and before proceeding with the job.

As someone once said of another mechanism, "C'est brusque, mais ca marche!", or as the Amateiur Radio fraternity say "Keep It Simple".

Howard

Thread: Use of Mercer dti
14/05/2015 18:51:04

By the sound of it, you have what is usually known as a "Finger Clock" (Often referred to as a "Verdict", one of the other main manufacturers of this type of device).

This "tenths" type of clock has a limited range of movement. It is intended to be used to measure small differences. As you correctly say, there should be a small preload. Most finger clocks have a range of about 0.020" or 0.040", so the preload should be about 0.005 - 0.010", because these are the sort of eccentricities or height differences that you should be expecting to measure.

In your case the stylus is coming clear of the work, because the eccentricity exceeds the range of movement of the clock.

Finger clocks can be obtained which measure in 0.001" increments.

Firstly, presumably, you wish to centralise the work on the Rotary table?

1)Set the clock so that it cannot move relative to the Rotary table. (A Magnetic base will make this much easier.)

2)Move the clock to give a small preload and adjust the Rim to bring the Zero to the Needle.

3)Rotate the Rotary Table until a maximun reading is obtained. If the stylus comes clear of the work, move the workpiece on the Rotary table by HALF the apparent error.

4)Reset and reZero.

5)Rotate the Rotary Table and remeasure the eccentricity.

6)At the point of maximum reading, move the workpiece by HALF the eccentricity,

(You may well need to do this in both planes).

7)Repeat these operations until the workpiece is centred on the Rotary Table to within an acceptable run out.

8) Ensure that the workpiece is firmly secured to the Rotary Table, and recheck that the workpiece is acceptably central. (Your decision as to whether within 0.0001" or 0.001" unless the drawing specifies the tolerance)

Once the work is set centrally on the Rotary table, you can begin to set the Rotary Table under the Spindle of the Mill.

1) Fix the clock to the head of the Mill and proceed as below.

You need to move the work piece, (Held on a Rotary Table on the Table of the Milling Machine) by moving the Table to reduce the amount by which the stylus fails to contact the work.

Again, this will need to be done in BOTH planes (X axis - along the table, Y axis to and from the column)

2)Reset the DTI to a small preload, and and adjust the outer rim to read Zero .

3)Rotate the Rotary Table, until a maximum reading is obtained.

4) Move the Table of the Mill to reduce the reading to HALF of the original value.

5) Repeat steps 1 to 3 until the DTI shows an eccentricity ("run out" which is acceptable to you.

6) Lock the Table on BOTH axes.

You are now ready to bore the hole to the finished size. Hopefully, the eccentricity of the already drilled hole is less than the depth of cut need to bring to finished size. If you are using a Boring Head, my advice is to take small cuts, and to take "spring cuts", (without altering anything), regularly, checking size after every cut. You may be surprised how much material is removed on a spring cut.

If you are reaming, check the run out of the reamer, when fitted to the Spindle.

A spindle which runs eccentric (not unknown) or a bent reamer will result in an oversize hole.

(Which is why, if possible, you bore or ream first, and then turn the male component to give the required fit.)

Sorry to go on at such length, but taking short cuts (PUN not intended) is likely to help fill the scrap bin rather than deliver a part to the required size and surface finish.

Hope that all this is of some help.

Remember the old adage "Measure twice, cut once" Wish that I did that regularly!

Howard

Thread: Rolling tailstock
14/05/2015 17:56:28

May I suggest using a device called a "Roller Box" (when used on a Capstan or Turret lathe)?

Model Engineers tend to call the device a "Running Down Tool" because it is often mounted on the Toolpost of a Centre lathe, rather than on the Turret of a Capstan or Turret lathe. Mounting one on the Tailstock of a Centre lathe will keep it central (which has to be done manually if Toolpost mounted) but may reduce the length of material that can be machined if the Tailstock does not have a through bore, and the Saddle reduces the proximity to the chuck.

A Roller Box carries an adjustable cutting tool, and two supporting rollers, but can be of two types.

It is effectively a travelling steady with a cutting tool mounted on it

One has the rollers leading the cutting tool (riding on the raw material), or the other type has the rollers trailing the cutting tool, (riding on the freshly machined material). The latter type is the only practicable one if the raw material is not truly circular, or is off centre.

The trailing roller type enables the machined diameter to be concentric with an existing smaller diameter.

The leading roller type enables the machined diameter to be concentric with an existing larger diameter.

Since the material is supported close to the cutting tool, it is invaluable for reducing the diameter of slender material, especially over a long length, with minimal taper, or risk of bending.

MUST get round to making one, (or maybe both types) one day! Add to the list of "Tomorrow" jobs!

Howard

Thread: Adding dials to lathe handles
13/05/2015 12:57:23

Have been loaned a copy of Introduction to the Adept Lathe by Andrew Webster (12th January 2008)

This gives the history of the Adept and Super Adept with some of its forebears, and competitors.

It is an interesting read. It confirms the Leadscrew as being 12 tpi pitch, but does not mention the pitch of the topslide or crossslides. Although from what I have seen on mine, would expect it to be 20 tpi (0.050" for one turn of the handwheel)

At the Spalding Show there were three Super Adepts. One has been modified by a former working colleague who has fitted graduated dials to his machine.

It gives his E mail as [PM Howard or Neil Wyatt for Andrew's email details].

The Lathes website will also give some info.

Howard

 

 

Edited By Neil Wyatt on 13/05/2015 16:44:05

Thread: Engineneering-homemade
11/05/2015 13:25:46

I am no electronics whizz, far from it!, but presumably the raw output is A C, and the voltage will vary, with the frequency, according to the speed at which the generator is running.

So having rectified the output, why not then wire in a regulator? A 7805 will give you a 5 volt output from your DC, which you can then use to power USB type devices.

If you want to charge a Lead Acid battery, a 7812 will control the out put to 12 volts. A 7815 would probably be a little high for a 12 volt battery, as a fully charged Lead Acid delivers 13.2 volts. (Although car alternators are 14 volt)

A 7812 would deliver the right voltage to charge ten NiCds, or NiMH, (which are 1.2V/cell) connected in series.

You might get away with using a 7805 to charge four NiCds or NiMh in series (4.8Volts), particularly if you regulate the water flow to ensure that the out put IS 4.8V.

Just a few thoughts

Howard

Thread: Imperial/Metric micrometer dials
11/05/2015 13:11:50

It is unlikely that Imperial and metric leadscrews would be mixed on a machine.

My impression is that Chester only sell Metric machines.

Are there no markings on each dial to indicate what each division represents?

There is no reason why a 20 (or even a 25) division dial should not be used on a Metric leadscrew.

20 divisions would give 0.05mm per division , 25 would give 0.04mm per division.

Why not use one of your Metric clocks to check the travel for one turn of each dial?

You may be pleasantly surprised.

Howard

Thread: Very Rusty Vee Blocks
22/04/2015 10:43:35

My wife uses cheap cola for cleaning secondhand cheap jewelry that she sells to raise funds for an animal charity.

Works well!

Also is good stuff for cleaning or fluxing for soldering. Dip a "bronze" coin in for a few minutes, and you'll see why we never drink the stuff! Phosphoric acid is a constituent, I think, which is what I use to deal with rust on car panels..

Howard

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