The Diary of the Building of a 5" gauge Stirling Single

Frames - Wheels

The material for the main frames with "Spectra Blue" applied ready for the marking out - which as you will see below was not needed!!!

Mention has been made to me to increase the cylinder bore to 1 1/2" to 1 5/8" else the loco is a little under powered. This would require Maid of Kent cylinders being obtained. I have decided to build with the existing cylinders as they were given to me by my mum.

Oak is required as a fitting between the front buffer beams of the loco and the read buffer beams of the tender. A friend, John Mallichan, has kindly donated a lovely piece of Oak duly signed by him so for  posterity if the loco were taken apart his signature would still be there. Thank you John.

Here you can see that they have been painted. They are in fact in three parts each side which is necessary to enable the "narrowing" in the frames to be achieved without resulting to bending the frames.

To-day is the day the that frames finally were riveted together.

First a counter sink was drilled to allow a very small amount of parallel material then the countersink to aid with strength.

The picture shown the frames and the various stretcher and drag boxes.

I have identified that I do not have the bogie stretcher. So that will be ordered!!

Wheels

Saturday 19th May 2009

A start was made on the loco wheels. The backs of all the wheel except for the main driving wheel was achieved but I have no way to hold the driving wheels in the lathe.

I have since doing this machining been told by a person with more experience than I that should have followed this order of machining:-

1. Knock the lumps off the FRONT of the wheel casting with whatever means. File, angle grinder etc..

2. Grip the wheel in the four jaw chuck and centre up as near as the casting will allow and push it onto the jaws of the chuck so long as both the front and the back of the wheel can be cleaned up. If the casting is distorted a bit then a compromise will have to be struck.

3. Face off the back of the wheel. Centre the bore, drill out and bore the axle hole, or for smaller holes a reamer will do the job if you can get the finish. Depends on whether or not you are going to press fit or use 'glue'.

4. Put a slight chamfer on the on the bore of the hole to clear the radius on the axle seating. It is important to have a radius on the axle to avoid stress corners. It is VERY important that the wheel goes up to the shoulder on the axle so that it will run true. Therefore it must clear the radius.

5. Do all the wheels in this fashion and do them all at once so that they are all at the same level of production.

6. Make a stub mandrel in the chuck and without removing it place the wheels each in turn upon it to finish them off. A fairly large diameter for the back of the wheel to sit up against will ensure true running of the wheel. Finish the front and the profile of the tread and flange. Job done.

So with this in mind please forgive the wrong method and may be when I checked I may have to buy a new set of casting of the driving wheels !!!!

Much of the day is taken up with my pottery class but the afternoon saw the finishing off of the basic turning of the 6 wheels leaving only the final bringing to overall size and providing the flange detail.

Later on Monday I made up CAD drawings for back plates to be used on the lathe to mount the wheels and emailed the drawings to the laser cutter.

Tuesday morning I received a telephone call from the laser cutter to say that the disc were all cut and ready to collect.

The picture shows that the plate was mounted on a face plates and then three 8mm bolts held the wheel in place.

This wheel has a diameter of 9.5" 241mm so it is quite the largest item I have turned in the lathe.

The two fixing holes were made as far apart as possible as there had to be a hole in the plate to allow the boss on the other side to stick through!!!

For the second wheel I will see if the bolts can be positions better to allow a full single final pass as it would make the machining so much easier.

I will be drilling and tapping three new holes further out in an effort to allow after a change of holes the cut could be continued right across the face of the wheel.

Still it could have been a whole lot worse and the picture actually enlarges the surface imperfections!!!

This picture shows how it started out as the casting with a very larger hub you machine away.

After nearly ten years of off and on use the reversing gears were torn to shreds.

As one gear was stripped so the other gear must have stripped.

These gear as purposely made of nylon / tuffnal so that and excess of load shatters the gears and does not damage the main spindle gear or those in the gear box train - well that's my story but I have been told it is not the case and they are made of tuffnal so that they will run quietly !!!!

I have replacement steel gears but I only use those to complete a process which I did in this case and am trying to order replacements but failing that as with these I shall have to cut my own gears.

Until the new gears are cut the turning will be by hand on the cross slide !!!!

So the first thing to do now is make up the blanks for the new gears and get cutting !!!!

What a shame I did not make spares ready for use - fine being wise after the event!!!!

I have now located a web site which can supply the gears and they have been ordered.

The new gears for the lathe arrived but as I had only one bush I fitted the gear and left the other gear as steel.

The back plate was reduced in diameter by 1mm and then I commenced to cut the front face of the main driving wheels and bought it to thickness.

Consideration has been given to the purchase of a reamer to cut the finished hole in the wheel for the axle but as it will only be used twice I have decided to use a new 9/16" drill but to first drill through with a much smaller drill and work up so that the final drill cut will be very small this will make the axle hole 1/16" small in diameter than to plan but will allow the job to proceed.

An early start at 07:00 and progress on machining the centre boss and drilling the 9/16" hole went well so much so that I have decided that I will buy a 5/8" reamer and complete the job fully.

The reamer should arrive in the next few days ...

The 5/8" reamer has arrived. I bored out the hole that had been drilled to about 0.4mm and then used the new reamer to complete the hole.

A very nice job it made too.

With the rear stop adjusted to the spacer thickness the cross slide was wound in 1mm the turning of the centre could commence until competed.

The outer edge and tread were then skimmed of the outer casting material and the wheel is ready to drill - bore and ream.

To finish off all the wheels arbours will be made to suite the size of axle hole and a large nut used to hold the wheel in place and the turning carried out very gentle. The arbour shown was for the small wheels -the only difference to the arbours for the big wheels was the diameter of the part for the wheel to sit on and the size of the thread.

Each cut is carried out to each wheel so there all end up exactly the same size !!! This does mean that the wheels are put on and taken off the arbours several time so it is well worth making a good fit to the wheel / arbour but not over tight.

I have a tipped tool I use for the final finishing cuts including setting the correct 20deg angle between tread and flange.

The tool is put in the cross slide after all the wheels in the set have been brought to size the angle to the flange is then cut. Thus is only used for very light cutting.

The tool is brought up to the flat face side of the wheel and clamped then the cross slide is turned through 20 deg and adjusted to take the lightest of cuts across the wheel and then cut the flange.

Here both the driving wheels are fully machined and only now need the crank pin location to be drilled and reamed.

I have received the following advice ( in red text) regarding the crank pins.

The main idea is to get all the holes as near as possible the correct distance apart.

Using a milling machine with a boring head (or it could be done with slots drills and reamers) you could do it in the mill as follows:-

1. Turn a bush to fit the centre bore of the wheel and just a little in length short of the wheel thickness. Drill a hole down the centre of the bush to allow one of your mill clamping bolts to pass through.
2. Clamp this bush to the mill table through the hole making sure that the cross corners of the nut do not overlap the outside of the bush.
3. Place this bush directly under the centre of the spindle by running a 'clock gauge' around it.
4. Lock the 'Y' axis of the machine. That is the axis that goes 'in and out'.
5. Now move the 'X' axis (left and right') the amount required for the distance between the axle hole and the crank pin hole. LOCK THE TABLE IN THIS POSITION.
6. DO NOT MOVE THE TABLE IN ANY DIRECTION EXCEPT UP AND DOWN (Z AXIS)
7. All you now have to do is pop the wheels in turn over the bush clamped to the bed and clamp the wheel down making sure that the lobe on the wheel is on the centre line along the 'X' axis.
8. You can now make the hole using whichever tooling you have. Either the boring head or a series of drills and finally a slot drill or end mill or reamer.

The former tools will not give such a good finish to the hole but it depends as to how you intend to fix the pin..i.e. either a push fit or one of the modern 'glues'. The latter method requires clearance in the hole for the glue anyway so surface finish is not so important. The main object of the exercise is to get the holes all the same distance apart and vertically square with the wheel. It will not matter so greatly in your case as you only have one wheel. but if you have coupled wheels and the pitch of the holes are not the same you will have trouble getting the connecting rods to run without excessive clearance in the bushes.

1. To the right your can see a photo of the plate on which to locate the wheel for the crank pin holes. Pin A is to fit the wheel bore and is fitted into the plate.
2. The clock is in the position to set the plate assembly to accurate alignment it with the spindle axis. After you have 'clocked' it up it is then clamped to the bed of the machine and the fore and aft axis clamped up.
3. The table is then moved for the next hole (crank pin) and, assuming you have a boring tool, this is bored to clear the tooling that you are going to use make the crank pin hole. If you do not have a boring tool then drilled holes will / should suffice. Also if you do not have a D.R.O. (Digital Read-Out System) on your machine then you will have to take account of the backlash in the table movement screw.
4. Lock the tables side to side movement and you are ready to machine the crank pin holes.

The jig in the picture is the one used by Roy O'NEILL when machining his crank pin holes in a lathe.

The groove between the two holes is done for a keyway alignment. Roy's wheels are keywayed.

If you are using a milling machine can I suggest that before you start to do any checking of the location of the clamping parts assess the position of the "Z" axis to ensure it is correctly positions to take the drills / reamer you may wish to use and then lock its position on the mill. Then the only part that can move vertically is them main cutting head. Failure to do this may result in inaccurate positioning.

So I have now turned a bush to fit the centre bore of the wheel making certain it was a little shorter in length than wheel thickness. Then I drilled a hole down the centre of the bush and made up a milling clamping bolts to pass through. I could not use the mills own clamping set as the centre hole of the wheel was too small!

Above the table I placed a section of metal that can be drill into through the wheel and clamped that and the bush to the mill table.

I adjusted the location of the table directly under the centre of the spindle by eye then made final adjustments by running a 'clock gauge' around it.

Please excuse the old "Boxford clock" but it is all I have and goes with my old Boxford ME10 Lathe!

Then the 'Y' axis (front to back movement) of the machine was locked.

The distance moved was then checked by using a laser pointer set into the drill chuck and digital calliper to measure and thus check that the position was correct.

From now on the table will remain fixed until all the drilling and reaming is completed.

The wheel is in place by not yet clamped down !!

That will wait until another session in the workshop as the total time to achieve this far has been 4 hours - may be I am just a very slow worker.