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[pettyofficernick]

What a grand job you are doing George, thoroughly enjoyed reading through.....

[ooyah/2]

What a grand job you are doing George, thoroughly enjoyed reading through.....

Nick,
Thanks for looking in, drag links arein the pickle jar so when they are cleaned  I will soon be in a position to try the engine out on air.

George

[ooyah/2]

Malcolm,
Your post confirming that the Calcs were for model engines seams to have been lost along with a reply I posted regarding the eccentric lift.

I had apiece of 5/8" dia bar which I chucked up in the 3- jaw and put a 1/8" packer made from gauge plate under 1- jaw and machined the eccentric.


I measured the size from top and bottom of the eccentric and it showed .220" so half of that is .115" which is .020" greater than the .093" called for in Stuarts drawing
So at present I shall leave the eccentrics as they are with the  lift that they have as I know that the engine will work.

If I had made a packer of .138" I would be afraid of the valve hitting the top or bottom of the steam chest inside

In the near future I will be machining up a set of Stuart SCORE casting that I bought on e-bay and at that time I shall do a little research into the eccentric lifts and try a packer of .138" and see what happens.

You mentioned in the missing post as I recall, that you have made up spread sheets of the eccentric lifts but they would not post on the forum, if you are able to send them via e-mail I would be only to pleased to send you my e-mail via P.M.

On consultation with some model engineer friends it would appear that when Tubal Cain ( TOM ) published these calcs it caused quite a furor'y in the model community,
some agreeing and some not which rumbled on for months with no final agreement or conclusion which I hope that this corespondance does't start it all again with others, as it is not my intention to do so.

George.

[malcolmbeak]

George


Very happy to send the spread sheet. It will be a few days as I am away at the moment.
I hadn't realised that there had been any controversy about this subject. I have to admit that I haven't checked my valve travel for any of the engines I have made using this method, but at least they all work very well. I guess I had better do a few measurements! Will let you know  the results.


Regards Malcolm

[ooyah/2]

George


Very happy to send the spread sheet. It will be a few days as I am away at the moment.
I hadn't realised that there had been any controversy about this subject. I have to admit that I haven't checked my valve travel for any of the engines I have made using this method, but at least they all work very well. I guess I had better do a few measurements! Will let you know  the results.


Regards Malcolm

Malcolm,
Thanks just when you are ready, my mail is down at present but should be back up soon, problems at Virgin.

MAKING and FITTING DRAG LINKS.

The drag liks were cut from a piece of brass angle which I cut into 1/4" thk strips 4 off.The centers were marked off and drill 5/32" dia and clmped in pairs before drilling.

Small bosses were made from a piece of 3/16" brass rod turned down at the ends 5/32" dia to fit the links holes, these need to be drilled and tapped 7ba after S/soldering as the heat can distort the threads .
Only 2- are tapped 7 ba the other 2- to have 3/32" dia holes bored.

I used 3/16" brass rod bought in the model shop, that stuff that is made in Chicago so be very careful when tapping as it's very soft and clogs the tap, the very first hole that I started to tap the tap broke so a new link had to be made.

After soldering it was just a filing job to bring the width of the linkds down to 3/16" or there abouts, a good polish and then the fitting.
All went well and it just remains to fit grub screws into the movement levers and the reverse lever.

George.

[ooyah/2]

FINNISHING THE LINKAGE AND TIMING THE ENGINE.

Having all of the bits and pieces completed the weigh shaft and the levers had to be pinned , on the shaft I used 3/32" taper pins and on the operating lever 1/16" roll pin.
When everything was operating smoothly the steam chest covers which are 1/8" thk had to be removed and  1/8" packers made in order that the assembly could be put together and I was able to view the position of the valve to time the engine.

Start by setting the quadrant in the mid position and the valve should cover all the ports , move it back until it's in line with the valve spindle and turn the engine over, the valve should move equally over the ports.

I like to start with the bent rod and when the engine is turned over which way you want it to run the valve should just be showing a crack with the crank just over T.D.C.
Do the same at the other end making sure that you are turning the engine in the same direction.
When this is done the valves should just be openning at T.D.C.  and B.T.C. in the direction you want the engine to run, if not you have to move the valve a touch in the direction needed to  get the valves openning as required.
You will never get them perfect but as near as posible, this is the time that using a grub screw in the valve buckle prooves it's worth.
Now start with the straight rod, use tha same proceedure and if the valves are not openning as described you will need to lengthen or shorten as required.

Once I was happy with the settings I rebuild the the steam chest taking out the packers and assemble the rods and levers, as there was a set of steam and exhaust pipes with the kit I couldn't resist the urge to se if the engine would fire on the compressor.

A first time hit and away it went both forward and reverse, this is what gives me the greatest pleasure in engine building, I tried to take a pic hoping that the tap wrench that was acting as a flywheel would show as a blurr but no luck, my camera must have quite a shutter speed.

I now can get on with the drive for the engine driven pump.

George.

[steamboatmodel]

It looks great, are you going to paint it?
Regards,
Gerald.

[ooyah/2]

It looks great, are you going to paint it?
Regards,
Gerald.

Yes Gerald,
OnceI have the pump and drive made it will all be stripped down and painted.

George

[ooyah/2]

George


Very happy to send the spread sheet. It will be a few days as I am away at the moment.
I hadn't realised that there had been any controversy about this subject. I have to admit that I haven't checked my valve travel for any of the engines I have made using this method, but at least they all work very well. I guess I had better do a few measurements! Will let you know  the results.


Regards Malcolm

Malcolm,
Some further observations as I progres with the build.

I just can't agree with the figures that Tubalcain has published, as I have said the 3/32" packer that I use leaves me .010" short in the travel of the valve over the steam inlets top and bottom.

If I had to use a packer of .136" that would give a travel .272" + the length of the valve at 1/2" is .772", the diminsion on the inside of the steam chest is .75" L x .563 W which means that the valve would hit the top and bottom of the steam chest and stop the engine from rotating.

Also if you have the book by Andrew Smith ( BUILDING A VERTICAL STEAM ENGINE ) on page 49 he recommends a packer of .138" for the eccentric which coincides with Tubalcains formula which I think is also wrong.

On taking another measurement on the finished reverse gear I find that I am still a little short but now by only .004".
I can't prove it but I am sure if I had used Tubalcain's formula the travel would be such that the valve would travel over the steanm inlet and uncover the exhaust port.

The engine runs very well in both directions on air so I still have to run it on staeam at a later date but I have no doubt that there will be any difference.

I shall stick to my way of making a packeras I know it works.

Thanks for your input.

George.

[ooyah/2]

BOILER FEED PUMP DRIVE.

Before starting on the boiler feed pump drive an Ali base plate had to be made to replace the box bed casting.
The Ali plate was cut from a 1/16" sheet and the holes in the plate had to be made to clear the engine big ends and the eccentrics.
The plate was mounted on the milling table with a piece of 1/4" ply below and all held down with clamps.
When completed I bought a length of 10mm Ali square from B&Q which was to be what carried the engine, the engine studs are tapped 7 b.a. into the Ali bar and up thro' the plate to allow the engine to be bolted down the the bed plate.

The plate was left oversize as I had not at this time decided on the position of the bearing blocks, the plate would be cut to size later.

I now had to make the bearing blocks and to machine and bore the gunmetal castings for the bearings.
The bearings are a simple drilling and milling the bases to size job before boring the fixing holes.

I had hoped to make the bearing blocks from a piece of Duralamin but I couldn't get the dimensions of the blocks that I wanted so they were made from a lenght of B.M.S  8" long x 1' x 1/2" , 2- pieces were sawn off and milled to size as a pair at 1.375" long.

Mark of the centers in the blocks and set up in the 4- jaw for turning the outsides to 7/8" dia down to leave the bases 1/4" thk.
When completed they were set up in the vice and milled down as a pair so that when the bearings were bolted down the centres of the Worm and wheel matched.
The last maching job was to mill a relief on the bases, I do this in case I have to alter the height of the block base to get the worm and wheel meshing, it's easier to take a little of the base pads than if the reliefe wasn't there.

Finally all holes were drilled and the bearings, bearing blocks and the cross shaft were fitted and the shaft turns over by hand.

Next job is the pump drive disc and the water pump to be made.

George.

[ooyah/2]

Today I started out to make the worm shaft bracket and bearing from a piece of Duralamin from an old bike crank, very high grade stuff.
I thought that I would have a nice pleasant afternoon using the rotary table and the milling machine.
All went well and I made the bearing from a piece of gunmetal scrap and pressed the bearing into the bracket.
Before final finishing and polishing I needed to bring the center of the bearing to 1/2" to the base which is the height of the worm shaft, here's where it gets nasry.
To machine the base plate to bring the cemnter to 1/2" would have ment that I had to machine all of the base plate off,  reason, I had measured wrongly at the start when setting up.
Another piece of the build now at the bottom of the river running at the bottom of my street, I do jest as I would not polute the river. !!!!
So I will have another go tomorrow, it's a good thing that the weather is so bad at present which allows more Shop time.

George.

[boneash]

Oh bad luck George !!

[ooyah/2]

Oh bad luck George !!

No sweat Boneash it's all a learning curve, what's that old saying,  HE WHO HAS NEVER MADE ANY MISTAKES HAS NEVER MADE ANYTHING !!!!!

 Thanks for looking in and your commiserations. .
George.

[ooyah/2]

WORM SHAFT SUPPORT BEARING .

A more successful afternoon, I made the support bracket from a piece of Ali using the same method of machining as the last one but made sure that the measuremnts were correct.
With a thicker base plate it allowed me to adjust the center size to mach the shaft, all in all a most pleasing afternoon, the worm shaft is 3/16" dia and while making the main shaft  of 9/32" dia the end of the shaft is drilled 3/16" dia x 7/16" deep to take the worm shaft, it's glued in with Loctite 603  and the worm is fixed to the shaft with a 3/32" dia roll pin.
Whilest having to make the new bracket I took the opportunity to make  the base a little wider, I think it looks better  and a much stronger job

I shall now start on the drive for the pump, the pump in the pics is a Stuart turner item machined from a casting, I don't particularly like the design of the pump so I shall probably make one to my own design from stock material.

George.

[boneash]

Well done George, a most suitable addition well executed.
So now another eccentric and con rod to produce !
A detail I realise I have noticed is that the wheel of the the worm and wheel appears to be straight cut and not dished to the radius of the worm for greater surface contact. Is this deliberate or due to the complexity to power transfer requirement not being a necessary requirement.??

[derekwarner]

George.....I have been following this engine build on a daily basis ...thankyou...but a few questions......

1. We understand the boiler feed pump displacement simply comes back to bore x stroke x speed....
2. is the worm wheel to worm reduction ratio approx. 40:1?
3. is there any deliberate design in having the worm wheel of considerable width/thickness?

Derek

[ooyah/2]

Well done George, a most suitable addition well executed.
So now another eccentric and con rod to produce !
A detail I realise I have noticed is that the wheel of the the worm and wheel appears to be straight cut and not dished to the radius of the worm for greater surface contact. Is this deliberate or due to the complexity to power transfer requirement not being a necessary requirement.??

Boneash,
I have to agree with you on the worm and wheel which I don't like.
However as far as I am aware that from the time Stuart started making the reverse gear it has been the same worm and wheel which I think is ugly with the wheel being too big, this is what you get when buying the castings from Stuart.
This was a set of castings that I bought off e-bay along with a set of launch engine castings both of which were bought from the same seller.

When doing reverse gear on D10's and 10V's I purchese the worm and wheel from H.P.C. gears which has the wheel radiused to suit the worm and it's advisable to purchase them in pairs to match, but being a bit costly I used the worm and wheel from the castings that I bought.
The worm is a 10 start and the wheel is 30 T giving 3/1 reductionfrom the engine.
Over time I have discovered tha 4/1 reduction and a slightly longer stroke is about right for these engines.

I enclose a pic of my Flashsteam engine which has the H.P.C. gears and this has a reduction of 6/1 from engine shaft with a 4- start worm, the engine does 15,000 r.p.m. free on the bench so the pumps are working at 2500 strokes/min. with no sign of war  and a D10 that I built last year for my S.T.CERVIA again 4/1 reduction using h.p.c. gears.

Derek I hope this answers your question as well.

George.

[ooyah/2]

George.....I have been following this engine build on a daily basis ...thankyou...but a few questions......

1. We understand the boiler feed pump displacement simply comes back to bore x stroke x speed....
2. is the worm wheel to worm reduction ratio approx. 40:1?
3. is there any deliberate design in having the worm wheel of considerable width/thickness?

Derek

Derek,
Don't know where you get the 40/1 ratio from but that would be far to much of a reduction to feed a boiler  round about 4/1 is about correct.
George.

[boneash]

Many thanks  George for your explanation, information and beautiful examples of your work.
good luck with the next sections and I and others look forward to seeing them

Rod

[derekwarner]

Apologies George...that was a typo......I counted what I thought were 10 teeth [from 12.00  to 9.00 [a quadrant] of the worm wheel......and saw the 10 start worm.....hence 4:1.......not as typed 40:1 .......

Image No 9 - Bearing Blocks clearly shows the components as an easily counted set.......Derek

[ooyah/2]

Apologies George...that was a typo......I counted what I thought were 10 teeth [from 12.00  to 9.00 [a quadrant] of the worm wheel......and saw the 10 start worm.....hence 4:1.......not as typed 40:1 .......

Image No 9 - Bearing Blocks clearly shows the components as an easily counted set.......Derek

Derek,In my post No 116 I state that the worm is a 10 start and the wheel has 30 T giving a reduction of 3/1 so I am afraid you have miss counted.

I don't know where Stuart get their gears from as I have hunted the web abd find nobody that does a 10 start worm.

H.P.C.  hoever do 4-3-2 and single start worms so on all my engines ,except the flashsteam engine, I use 4 start worms and 16 T wheels to give 4/1 reduction.
H.P.C. gears are all matched  to whatever combination you buy but you can't mix them, the are so much smaller than the monsters Stuart use and in my opinion much neater.
I may even consider thining the wheel down.

George.

[ooyah/2]

Many thanks  George for your explanation, information and beautiful examples of your work.
good luck with the next sections and I and others look forward to seeing them

Rod

Thanks Rod,
Tomorrow I have a whole day to myself, Mrs T is off to a ladies Conference , so I shall have a go at the drive disc on the cross shaft and maybe get the connecting rod casting supplied machined and fitted.

George.

[ooyah/2]

PUMP CON ROD AND DRIVE.

No1
Started of by chucking up a piece of 3/4" dia M/S bar and machined the boss 7/16" dia  x 3/8" long   and bored and reamed the hole to take the  1/4" dia icross drive shaft.
With a parting tool part of 1/2" long from the face of the machined disc.

No 2.
Put a piece of 3/16" thk material in one of the jaws in the 3- jaw chuck to off set the 7/16" dia boss  and turn down to leave a 1/8" thk disc and the drive pin to .281" - .0005" dia.
While in this set up drill and tap the drive pin 6 ba x 3/8" deep, at this point machine the drive pin to 11/32" long.
Clean up all sharp edges and remove from chuck.

No 3
All the components of the Pump drive.

No4.
Cross shaft and pump drive fitted.
Cross shaft was glued into the 1/4" dia reamed hole in drive disc with Loctite 603 and cross pined with a 1/6" dia roll pin.

No 5.
Con rod center of 9/32" dia drive pin was marked off and set up in the 4- jaw to center and drill the drive pin hole.
Hole was drilled and reamed 9/32" dia and the Con rod had .032" to be taken off of both side to bring it to 5/16" thk., did one side, turned it around in the 4- jaw and machine the .032" required.

This was a very poor gun metal casting and the drill was inclined to wander a little when boring so drill it in steps before final ream.

No6 & 7.

The Cross shaft and pump con rod fitted, the rod end still has to be machined flat to 1/8" to fit into pump ram, so next step is to make the pump, still not sure whether to use the Stuart pump or make one of my own.

George.

[Ramon]

Hi George, just caught up with this - very nice work indeed    there will be some flattery appearing in a few weeks I can tell you 


Not wanting to teach granny here but with regards to the gears the ones you are using on the D10, are these not helical gears as opposed to a worm and wheel as per the HPC variety you have. Hence the straight cut wheel as pointed out as opposed to a true worm wheel which is usually concave to follow the radius of the worm.

HPC do helical gears so you may be able to find the same combination there.


Thanks for your recent mail, Keep up the good work - I'm away to Peterborough tomorrow so I'll be in touch on Monday.


Regards - Ramon

[ooyah/2]

Hi George, just caught up with this - very nice work indeed    there will be some flattery appearing in a few weeks I can tell you 


Not wanting to teach granny here but with regards to the gears the ones you are using on the D10, are these not helical gears as opposed to a worm and wheel as per the HPC variety you have. Hence the straight cut wheel as pointed out as opposed to a true worm wheel which is usually concave to follow the radius of the worm.

HPC do helical gears so you may be able to find the same combination there.


Thanks for your recent mail, Keep up the good work - I'm away to Peterborough tomorrow so I'll be in touch on Monday.


Regards - Ramon

Ramon,
You are quite correct, the gears are Cross shaft Helical, not worm and wheel.
On contacgt with Stuarts in the past they refered to them as worm and wheel so I continued with this description.

I don't like the Helical gears as they are very over size and in my opinion just don't look correct for this application but as I had already bought the castings these were with the set.

If I was building from scratch I would purchase the worm and wheel set at 32 D.P. from H.P.C. which I have used on various occasions on other Stuart engines and on my flashsteamer and these from H.P.C. give very accurate centres between worm and wheel, in the Stuart drawing you have to scratch about to find what the centers are .

I had overlooked that H.P.C. did the Helical gears to give 3/1 reduction but the wheel at 30t is 1.061 " dia which is bigger than the Stuart issue and would look even worse.

The nearest that can be found is a 4 start worm and a 16t wheel  to give 4/1 which is close enough to Stuarts recommendation of 3/1 and if I wanted to pass more water I would either increase the pump stroke fro 5/16" tp 3/8" or increase the dia of the pump ram from 1/4" dia to 5/16" dia. possibly do both and fit a bypass valve.

The last D10 that I built and is now installed in a 42" long St CERVIA  x 32 lb weight  has the 32 D.P. worm and wheel at 4/1  which is adequate to feed the D10.

Look forward to hearing from you and thanks for keeping me in line.

George.