Sweet Pea build

[Barneydog]

Hi Guys,

Did a couple of jobs today. I turned a couple of  MDF disks to represent wheels and fitted a dowel of wood to each to act as crank pins. A length of dowel as an axle completed the set. These were used as a test for my new wheel quartering jig. I deliberately left the axle sticking through the wheels for something to measure against. I am glad to report it worked very well. It is now ready for use.


Next job was to clean the return cranks and a quick dip in the nickel plating. As they are made from mild steel this will hold the dreaded rust at bay rather than spraying them. I can always change my mind at a later date and spray them.


The return cranks on this loco are set up as the crank pins are fitted. I put a small saw cut on the end of the drive pins to line up with the slot that runs along the return crank. Once the pin is fitted the crank can be removed and replaced easily without disturbing its alignment. I drilled across the crank and the end of the pin to fit a roll pin to add further security and accuracy.

I turned the end of a short length of M6 threaded rod to a sharp point. Two nuts and two washers were used to hold it on the return crank.

You will remember when I finished the wheels I made a mark on the rear wheels for later use. This is the time for their use. The jig described in the book does not suit the changes it the diameter of my crank pins and axles.

The return crank is pushed into its hole bored in the wheel and this pointer is used to align the end hole accurately onto the mark. Using the nuts the pointer is set to just touch the surface of the wheel crank boss.

After a couple of practice fittings I was ready to glue it in. I put some loctite retainer on the end of the crank pin and pushed it into the wheel but not aligned with the locating mark. I then turned the crank assembly to align the pointer with the locater mark. This allowed both accurate location of the pointer and rotation that distributed the loctite around the joint.

After a couple of minutes the joint was set well enough to allow me to gently remove the pointer and place it onto the crank of the other wheel. The smaller crank pins on the front wheels merely need to be glued securely into their holes. All four have been left to cure until tomorrow. I can pin them tomorrow to ensure they can never move under any circumstance. I cleaned off the excess loctite from the face of the wheel and will clean the remainder with methylated spirits another day.


My next task will be to add the extra pins in the back of the wheels and then quarter and glue the wheels onto the axles. I will post a couple of carefully selected pics of the quartering but am at the moment not able to show the whole quartering jig to you.

Cheers

Julian

[Barneydog]

Hi Guys,

Been a few days since I posted on here. I have been writing an article for a magazine on the construction of my Quartering Jig and in the process quartered the wheels for this loco. I have in fact quartered them twice. I set the crank pins wrongly the first time. I set the left crank ahead when actually the right crank is specified to be ahead. Then today I realised I had forgotten to put the eccentric for the water pump on the rear axle so had to remove a wheel again to do it. This was the price of doing several things at once. One of them will always go wrong.


You may not have noticed in the above pictures the spacers. These are the spacers I made when I turned the axles.
While the loctite was curing today on the rear axle I set to my next task. Before the wheel and axle assemblies are able to be installed in the frames I have to start on the suspension. In the book the rear suspension has rubber blocks rather than springs. This is to stop virtually all movement of the rear axle as any movement will alter the valve timing and so made the loco run roughly. There are some plans available for a mod to stop this movement and return all movement to the rear suspension. Rather than the motion shaft and gear sliders being fixed to the frame this mod attaches them to the axle boxes so it all moves together and holds the timing in the correct position at all times. I started the plates when I made the axle boxes and will continue with them later.
Having chosen to have split axle boxes on this loco I have had to alter the machining of them slightly to allow for extra holes. This also includes some extra holes on the rear axle boxes to accommodate the previously mentioned plates. Obviously all these extra holes have to avoid each other.

My plan is to make some spring guides that can also double as the bolts that hold the two halves together.
These have been turned from 5mm stainless steel rod with the end turned down to 4mm and tapped to M4.

When screwed into position they look like this.

When in position in the frames they look like this.

Here lies a problem that needs rectification. When I chose the position of these pins I did not allow for the positioning of the plate that is bolted on the frames to hold the top of the springs. This is a piece of 5/8" angle iron 1 3/4" long and held to the frames by three M4 bolts. The angle face has two holes to accommodate the pins and against which the springs push. To allow clearance this angle on the rear plates have been milled down to just under 1/2". The angle iron is 1/8" thick so will not fit with the springs and pins in this position.
To rectify this problem I replaced the pins with the stainless caphead bolts I had originally used. I countersunk the holes with a 7mm drill to recess the cap heads flush with the surface of the top of the axle boxes. I then drilled and tapped new holes next to these bolts to move the pins 5mm towards the inner faces. The pins had some of the treaded part removed to fit these shallower holes.

This revision should sort the problem. The springs are slightly too long and will be cut down later to adjust the ride height.
Once the plates are bolted on the suspension looks better and has free movement. The zip tie is to stop them dropping out while the others are completed.


I am happy with how these have turned out now that all four are completed.
Tomorrow I hope to cut the springs down a little. They can be adjusted further later if needed. I can then fit the wheels and axles and start on the coupling rods.

Cheers

Julian

[Firebird]

Looking good 

Cheers

Rich

[Kim]

I have in fact quartered them twice....

So, if you've quartered your wheels twice, does that mean you've halved them?   


Nice work on getting them quartered and on resolving the issue with your spring guides.  It looks like a great solution.
Kim

[Barneydog]

Hi Guys,

Thanks Rich.

Very quick of you Kim but you missed the axle that was quartered three times!

To todays efforts.
Now that the glue on the axles has cured I am able to pin them together for added security. I drilled on the edge of the axle on the face of the wheel. The hole when drilled is half one the axle and half on the wheel. It can be viewed as the round equivalent of a key way. The hole was 3.2mm and was tapped M4. I only drilled about 10-15mm deep. I have some stainless 10mm M4 grubscrews. With a touch of threadloc I screwed one in each hole until flush with the surface of the wheel face. Both front wheels had one each and the rear wheels had two. I decided to put two on the rear wheels as they have more stress from the pistons. Eventually these will be hidden behind a coat of paint.

The rear axle has the pump eccentric in the middle which needs fixing to the axle. It has two holes drilled through to the axle hole in the centre. These are tapped M4. I screwed a stainless M4 grubscrew into one of the holes to hold the eccentric in position. I ran a drill through the other hole to put a small dimple in the axle. A grubscrew was screwed tight into this dimple with another behind it. This second grubscrew is to be a locking screw for the first one. The grubscrew was then removed from the first hole and the drilling of the dimple repeated in this hole followed by two grubscrews. To balance out some of the stress on the axle the widest part of the eccentric is positioned opposite the centre of the two cranks.
.
Next I cut 5mm off the end of all the springs. I used a 1mm blade on my angle grinder. This cut the springs very well and gave a flat end all in one action. The cut face on all the springs has been positioned to the top of the suspension. Next I thoroughly cleaned the axles to remove all excess Locktite. I don't want to inadvertently glue the axle boxes onto the axles. I split all the axle boxes and fitted them in their correct positions on the axles. With the springs on they are ready to fit to the frames.

With the wheel assemblies in their horns and the keeps bolted on they sit very well in the frames.

Once flipped over the wheels look good in their correct places. They turn easily. They are not tight and had a touch of grease when the boxes went on the axles.

As my next job is the connecting rods and coupling rods I decided to temporarily remove the wheel assemblies and to paint the frames. This will save removing everything later. I used smooth black hammerite applied with a brush. I only did the two main frames and stretchers both inside and out. The buffer beams will be done later. I don't mind the slightly rough finish that brush painting gives as it will make the frames look more "industrial".

For the coupling rods I need some bars of bronze and steel. The rods on this loco are the marine type so have two "brasses" sandwiched between two steel plates. One steel plate is fixed to the rod and the other acts as an end cap. For the brasses I am using bronze and for the plates and rods I am using stainless steel. The brasses are availabe as a casting but I have not got one but have plenty of phosphor bronze. I have milled two pieces of bronze to the correct profile of 3/8" by 7/16" There are two pieces that are 5" long. I milled some stainless 303 hex down from 12mm to flat bar 3/8" wide to match the bronze. They are not as thick so were machined to 5.5mm. They are 303 as this machines, drills and taps easier than other grades of stainless. These bars are 6" long.


Tomorrow they will be clamped together and machined to make the ends of the coupling rods.

Cheers Guys

Julian.

[Barneydog]

Hi Guys,

As a small aside you will have noticed the frames are mounted on a "spit-roast" frame to support it and allow it to turn through 360 degrees. I built it a while ago. It is in two parts which allows it to accommodate any size of loco. The green bar that disappears behind the buffer beam is clamped to the centre of the buffer beam to hold the frames. The arms can be adjusted for height at the turn of a couple of wheels.

It may be of interest to many of you and especially Kim to see a photo of these wheels.

They are quite literally wheels! These are 110mm steel disks machined as a test to cut wheels. They were drawn roughly on my computer as a tester and then machined on my CNC mill. With more work on the computer they can be made to look better. They can also be scaled to any size. With CNC they will all be identical.

Kim. I have just looked at your Penn Switcher build posts. I admire your wish to use entirely barstock. This build will only use castings if they came with the original purchase of parts. From now on it will all be barstock as I have used all the castings I got. Have you considered CNC rather than your milling process?.

Cheers


Julian

[Kim]

That is a great looking wheel, Julian!

I don't have any CnC and I'm currently not interested in it.  I may be someday.  But for now, I'm quite enjoying spinning the cranks to get my jobs done.  I work with computers all day long and am not really interested in coming home and working with them in my spare time too.  But I won't rule it out completely!  I can see me being drawn down that path at some point.  But for now, it's all manual.

It's more the journey for me.  I'm just trying to learn and have fun, don't have any big plans to run it around a track yet.  But again, that may change!

Thanks for sharing your pics.  I'm really enjoying following the progress of your Sweat Pea.
Kim 

[Barneydog]

Hi Kim,
Thanks for the comments. The wheels were very quick and roughly drawn to prove we could make them. They were going to be for a project myself and Rich were planning a while ago. I needed two handwheels so they had a use in the end.

I don't use cnc all the time but it is a useful tool to have access to.

I am sad you have no plans to run on a track. For me the journey is interesting and fulfilling but also has to have a purpose. I have five grandkids who want to be pulled along the track. At least two want to drive it themselves.
We have full access, in normal times, to use the track at our club at any time. Rich and I are looking forward to taking a couple of loco's, a bag of sandwiches and a flask and chuffing round all day in the summer sun. Part of the journey has to be learning to run our loco's.

Cheers

Julian

[Barneydog]

Hi Guys,
Carried on with the coupling rods today.

These pieces need to be clamped together. I clamped the two stainless bars together in my vice. I drilled a 4mm hole at each end so a bolt in each will allow the bronze bars to just fit between them. The top bar is marker for cutting and drilling. It is marked so when cut there are four pieces 1 1/8" wide. This will be the finished size so there is an allowance of 3mm between each. Each part has been marked for drilling. Two holes 13/16" apart and one dead centre of them. All are in a straight line centrally in the material. The red in the next picture is marker pen which show scratch lines well. I use it instead of engineers blue. All the holes have been centre punched and started with a centre drill.

All four pieces are bolted together on a flat surface to keep them level. They must not be overtightened or the top and bottom bars will bow.

The cut lines are marked down the face using a square. The centre holes are used with the square to mark the middle of each part ready for drilling and reaming later. The centre is marked on the bottom face.

This sandwich will now stay together until all the drilling and cutting is completed. It was clamped into the drill vice with the top bar uppermost. The centre holes on the top are only for centering in the lathe later so only need a dimple drilling in the surface The holes each side are drilled 4mm. I set the stop on my pillar drill so the drill bit only goes through the top bar and both the bronze bars. I drilled one of the holes near the middle of the sandwich. The base bar was then drilled 3.3mm and tapped M4. A bolt was then screwed in tightly from the top. I started here rather than one end so this first bolt can hold the bars tightly in position. The block went back into the drill vice and all the other holes were drilled 4mm. A quick change of drill bit to 3.3mm and the bottom bar is drilled through the holes. The block is turned over and the centre holes are drilled most of the way through just the bottom bar. The other holes are all tapped M3 and bolts tightened in. These are not the eventual bolts but are some that will do for now.

The bolts are trimmed flush with the bottom.

I drilled the holes in the centre of the side face for use later to centre in the lathe. Into the bandsaw and the four brasses are cut. They are slightly too long but will be finished and sized later in the process.

Each part is then machined in the four jaw in the lathe. A bit of 18mm MDF is a spacer to hold the parts square but slightly forward of the jaws. Each part is aligned with the centre using the hole drilled in the side face. This hole is then drilled out and reamed to 1/2".

It was drilled at a very low speed in case the drill grabbed the part. Luckily all four had no mishaps.

While still in the lathe the face is turned to clean it up and square it to the hole. I then turned it round to face the other side. No need to reset it centrally as this is just to face it.

I have marked the back of each piece with spots so they always stay together as sets. I have written "out" on the outer faces so I don't inadvertently fit them to the rods the wrong way round so leaving the spot markings visible.
Tomorrow the holes started in the bottom plates can be opened out and the rods made and fitted into them.
My last job today was to put the wheel and suspension assemblies back into the frames. T painted the bosses and the end of the axles black so it can dry overnight. I have used black hammerite but may change the colour later.


Cheers

Julian

[Barneydog]

Hi Guys,
A small amount of progress to share with you on the coupling rods this afternoon.
I tried all the brasses on all of the wheels to find the best fits. The pin on one of the front wheels is a fraction narrower than the others by about half a millimetre. I had to put the narrowest brass into the lathe and skim a small amount off until it fitted. It was labelled ready for this wheel.

Two brasses were parted for the right side wheels. The base plates on both had the centre hole drilled to 1/4" in the pillar drill.

I have some very nice chromed stainless rods 3/8" diameter. In the lathe one end has a shoulder turned onto it 3/16" wide and 1/4" diameter to fit the hole in the base plate.

 The rod was removed and lined up with the brasses. Measuring from centre to centre the coupling rod need to be 8 7/8" long. The 3/8th rod was marked just over the size needed. I added half a millimetre or so on for adjustment later.

The rod was cut and then put in the lathe to turn the end to take the other brass base plate.

The rod and two base plates were set up on some flat vermiculite blocks for soldering. This setup ensured the base plates where soldered on level with each other.
After cleaning up the rear brass was assembled on the wheel. With the wheel at dead forward the rear wheel it turned so the crank pin enters the cup of the bottom brass.

The bottom brass is then adjusted until the wheel will turn through dead forward without binding or catching. To make sure both were also tested at full rear centre. The bottom of the base brass is filed or sanded to get the fit correct. I found a sheet of 60 grit wet and dry flat on my bench worked very well for this job.

This is the only place that can be filed to adjust. It does not matter which brass is used to make the adjustments. Once done the second brass can be bolted together to make sure the wheels will still go past centre. A light movement of the wheels is needed. Any catching or binding can be felt through your hands. It can be felt when it catches even though you cannot see it.

All parts of these brasses have been stamped on the bottom edges with RF  and RB for right front and right back. This helps keep them on the wheels they were set up on. This coupling rod was removed and put aside for later. The whole process was then repeated for the left hand coupling rod and of course marked accordingly LF and LB. These rod are set up like this one at a time so they don't interfere with each other while sizing. This adjustment is the reason for the extra half millimetre. If they are too short they need shimming to adjust. It is far easier to gradually remove than add.

Next time I am in the workshop I need to test the wheels with both coupling rods on and to drill the oiling holes in the brasses. I can then move onto the connecting rods. This will not be until Wednesday afternoon.

Cheers

Julian

[Kim]

I wouldn't say that is small progress - it looks like a lot of work to me, Julian.
And it's quite the fascinating process!   

Kim

[cnr6400]

 

The soldered coupling rod does save some tricky lathe turning and end drilling on a long workpiece to make this style of rod, but a one piece profiled and bored plate style coupling rod would be much easier to make accurately, as you aren't working around two wide-tolerance soldered joints. Just food for thought for the next engine! 

[Barneydog]

Hi Kim,
thanks for your continued interest and comments. They are much appreciated.

Hi cnr6400,
Thanks for your comments but:-

1.These are the style and construction detailed in the designs of this loco.

2. The crank pins on this loco require split brasses as they are held in place by shoulders machined onto the pins. Fully machined would not go on.

3. The tolerances involved are perfectly adequate including the silver soldering if done carefully. The faces can be cleaned up and squared on the a disc or band sander. They actually were not far out. The accuracy is there once they are adjusted.

4. The machining required to make solid coupling rods has by necessity to be measured and machined very accurately to fit and work first time. The beauty of these was that by making them half a mil longer I could adjust them until they fitted perfectly.

5. My next loco will probably be a part built 7 1/4" Singapore 0-4-0, I have acquired, which if I remember correctly has fully machined coupling and connecting rods. These where so easy to make, fit and adjust that I may change the fully machined for this style.

Thanks for your comments. The food for thought is appreciated.

Cheers

Julian.
 

[cnr6400]

 

[Barneydog]

Hi Guys

Had a few hours in the workshop today.
The coupling rods need the oil ways machining in. This is a simple task the merely needs a 1.6mm drill and a countersink. Drill a 1.6mm hole through the top of the brass where the two parts meet. Previous to this the bolt needs to be removed. Drill through the bolt hole into the bored hole that will have the crankpin in. Use the drill with the countersink bit fitted to make a small well.

Split the brass and countersink the top bolt holes on each half. This will allow the oil to pass by the bolt.

Fit both the coupling rods and then turn a wheel. I have a video of this that needs to be stored elsewhere to allow you to view but trust me turning one wheel turns all the wheels with no binding. I must admit I held my breath at the first turn in case the quartering was wrong but glad to report everything perfect.
According to the build book I need to clean and size the edges of the brasses. One end goes near enough centrally in the four jaw chuck and the other end has the tailstock centre in the previously centred hole in the top plate. Thurned in the lathe the brass can have the outer edges turned to a curve.



FORGET IT!!!! That process will take hours. I used a file and cleaned and curved the edges of all four brasses in five minutes.

Next job is to start the connecting rods. These go from the crossheads (not made yet) to the rear crank pins. The brasses for these are made in the same way as the coupling rod brasses but are thicker. Instead of 3/8" they are 1/2".

They are marked, punched and drilled in the same way.

Once drilled they are cut in the band saw.

Into the four jaw in the lathe and drilled to 1/2" and faced to fit exactly onto the crankpins of the rear wheels.

Once cleaned up they fit nicely.
.
Eventually they will be retained by the return cranks which will be refitted hopefully tomorrow and the rest of the con rods completed.

Cheers

Julian