Has anyone built a SweetPea? Advice needed.
Martin
I am considering (means desperate to start) building the 5" Sweet Pea.
Searching the internet, I have studied the excellent Craigmill
Engineering pages, but it doesn't look as though he has finished it
yet.
Anyway, I am undecided on the following points.
An 040 is going to be easier to build than the 042 version, and I
suppose that loads of 040s are running about, is this a good choice?
Superheated or not? My 16mm engines are better superheated, as there
is less condensation in the cylinders, but they have very tiny boilers
and pistons.
Pumped lubrication, or displacement? Jack Buckler suggests that steam
oil should not be used as it is too thick, but I am using the model
grade in my 16mm stuff, and they empty the lubricator no trouble.
Obviously, the more sophisticated the engine, the better it will
perform, I can see that, but will the simpler one perform adequately?
Finally, Blackgates do a starter kit for the chassis, that includes
everything needed. I phoned them, and it doesn't include cylinders
etc. but seems a great deal more expensive than their list prices for
castings and materials. Are there really about £70 worth of nuts and
bolts needed?
They didn't seem very helpul on the 'phone, or by email, but I guess
they are busy people.
Cheers
Martin
Dick Ganderton
add a pony truck. This meant that I had to set the completed frames up
on a very large mill and cut out the clearance bits for the pony truck
wheels. If I was starting from scratch i would certainly cut out the
clearance bits for the pony truck wheels - just in case I changed my
mind.
Build the boiler with superheated flues - you can always omit the
superheaters if you decide to have it 'wet'. If you don't put in the
superheater flues you cannot ever superheat it.
Displacement lubricators every time - with sight feeds, one per
cylinder.
I have left out the axle-driven pump as I don't like them. I have,
however, made the frame stretcher so that a pump could be fitted later
if someone else wanted to. I am fitting a couple of injectors but I also
fancy a donkey pump as well, just for the hell of it!
There are several errors in the drawings that you need to be aware of,
particularly with regard to the axleboxes, springs, and associated bits.
Regarding the cost of Blackgates starter kits, i only bought the wheel
castings from them and even those were not SP ones but Edward Thomas
ones. I made my own patterns for the rest and had them cast by the local
foundry - unfortunately long since closed down.
Martin
How can I have sight feeds with displacement lubricators? I have sight
glasses on the drip feeds on my Myford, but I don't see what you mean.
I think I will get the frames for the 040, I like the idea of laser
cut, and all the holes marked, as this will save a lot of time, (until
I find one hole wasn't marked and it has to come apart again).
Do you have a list of the errors and corrections?
I think I will get the chassis kit, if it is all there, there is
nothing worse than needing a 6" length of bar, and having to drive 20
miles to get it :).
Regards
Martin
Racker
Goes to show how different people have different ideas.
I also added the pony truck setup after having built the frames, it
makes for a much more stable engine with a lot less pitching.
As for super heating, I didn't bother, but I did increase the boiler
gauge thickness to allow running at 100psi, although it never needs
much more than 70 for hauling its usual three trucks, and people have
often remarked about the steam oil (400 grade) bubbling nicely on the
cylinders after a run.
I used pumped lubrication with a manual primer as the displacement
types had a tendency to gulp their contents if the regulator was
closed quickly, especially on a downhill run. Additionally a snifting
valve was fitted to each valve chest cover to prevent vacuum build up
on the over run ( these are also ideal to unscrew after the days run
to fill the cylinders with oil for storage).
I tried a couple of injectors but without much success, the saddle
tank gets too hot in use, so the water is nicely preheated for the
axle pump to feed directly, this pump was increased in bore size by
1/16 from the standard 'just in case'.
I have also fitted a Stuart donkey pump, and with this just idling
away, will keep the engine in steam and water almost indefinitely. In
this mode it has been used as a stationary steam generator for some
static models during some of our shows.
I also went for the full cab option and steam brake controls for the
driving trolley.
I mostly built to the original 'Buckler' drawings with assistance from
the EiM articles, with one obvious mod to not use the rubber springing
on the rear main axle but to use heavy springs with the axle box
movement limited so as to not throw out the valve timing.
As for Blackgates, I found them a bit slow on supply as they kept me
waiting for parts in excess of 12 weeks.
Completed in 1993 after about 5 years in the building, the engine has
covered many hours and miles in steam and has proved to be a pleasure
to run, with very few reliability problems.
John
GPHawksford
version. Sticks to the track like glue and well worth the extra work.
No superheaters, they are more trouble than they are worth and the gain is
negligible. Also wet steam reduces cylinder lubrication problems. Definetely
displacement lubricators, but ratchet type as the clutch type just don't seem
to last.
Overall a superb engine, well designed, runs superbly, very forgiving. I have
always found Blackgates excellent and am currently building an 0-6-0 version of
Sweet William, (a Sweet Pea in 7 1/4).
The book on the Sweet Pea is very useful but each builder develops his / her
own tricks to make the work easier and more accurate. You would get a good idea
of what is happening and have the chance to see and talk to sweet pea buliders
at the annual sweet pea rally, to be held in Morecome this year.
Kits of bits are very well but pricey, much more fun to do it all yourself !
E mail me if yuo think I can be of assistance, good luck.
Dick Ganderton
"hydrostatic" with sight feeds. Far superior to a mechanical lubricator
with much more controllable oil feed. No problems with "gulping" and you
can drive all day in a clean white shirt and on one filling of the oil
tank!
The problems with the drawings around the axleboxes is that the holes in
the top of the axleboxes for the spring pins are not in line with the
holes in the top spring plates. This means that the spring pins won't
pass easily through the top plates. Also, with the spring plates as
drawn the spring pins are not long enough to reach the plates! Turn the
plates upside down and the springs are coilbound long before the
axleboxes reach the top of their travel. Also, with the plates in the as
drawn position you cannot get the nuts on the bolts holding them to the
frames as the springs get in the way - or rather with the nuts in place
you cannot fit the springs.
My solution was to do away with the springs and go for a compensation
system with a rocking beam on the front axle and the rear axle locked
solid in the horns. The axleboxes have needle roller bearings and are
connected by a stainless steel tube to form a cannon axlebox assembly.
The pony truck axle runs in a pair of ball races.
I have fitted Jack Buckler's "Jacobs Ladder" valve gear modified to have
miniature instrument ball races on all the pivots.
Martin
I have ordered a kit to build the chassis, as an 042.
When it arrives, I will have a good look at the rear springing in the
drawings. It seems to me, that what is required is a short travel,
compliant suspension, exactly what would be provided by rubber blocks
:)
I'll be back in touch when I get stuck!
Martin
Racker
Trouble with the rubber blocks is that after a couple of years running
the lubricating oil makes them change into a horrible mess.
I didn't have a problem with the spring pin alignment between the
spring plates and axleboxes, as I set the whole thing up on the
milling machine with the axle boxes clamped in place and drilled right
through the plates to the axle box in one hit.
I also used roller clutches on my lubricator pump with no problems so
far, although the drive shaft is hardened with the oscillating drive
taken from the axle pump eccentric. Be interested to see a ratchet
driven displacement lubricator :o))
John
Colin MacEke
Mechanical pros- fit and forget apart from topping up.
cons- takes a time to get the delivery quantity right. most people over oil.
Hydrostatic pros- good control of amount flowing (3 to 5 drops a minute)
cons- You always seem to be fiddling with it to keep the control right.
When the engine is stationary it is still putting oil into the cylinders or
at least ready to go into the cylinders so that after along wait in the
station, you can get too much coming through. Construction is more
complicated.
Colin