Model Engine Maker
Engines => From Kits/Castings => Topic started by: warrenmaker on May 13, 2018, 08:57:34 AM
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Hi guys,
my first attempt at building a model steam engine; or any engine at all for that matter.
Package arrived all the way from UK to Melb, Aust in 5 days. TNT express certainly know the meaning of express! :ThumbsUp:
I must admit to being a little disappointed after the original excitement had worn off. The plans were so faint I could hardly read many of the dimensions. The castings were pretty rough (certainly inferior to an old Stuart I had purchased second hand a few months ago.) They will require a lot of hand finishing.
Also they seem slightly undersize; to the point that there certainly is no room for errors. Measure 5 times, cut once will definitely b the order of the day here.
is time to make a start. :cartwheel:
First up was to get the base sitting flat on the mill table. I did this by shimming one corner with an appropriate feeler gauge. Then running a cutter over the appropriate surfaces to correct height.
Then I flipped it up side down and skimmed the base flat.
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Then the bearing caps were machined and fitted. Sounds easy when u say it fast. But the bearing caps alone took me 4 hours.... :facepalm:
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I am waiting on the correct size drill for my reamer so I can drill and ream the bearings; so onto machining the standard.
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Thanks for posting pictures of your build, looks like a very good start on what will be an attractive engine. The trunk column held with the slotted clamps on the f'plate is a nice example of classic "Stuart Turner" vertical engine machining set up! But I note what you have said about the rough castings and lack of "meat" on them, that's not good.
Dave
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A good start to a fine engine .
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Hi guys, can any one help with a dimension please... it simply is not shown on the plan for the Stuart 7A. I can't figure out the overall length of the cylinder head.It should b shown on drawing #1 on the plans but not on mine. :headscratch:
Any help would b appreciated ,
thanks in advance. :help:
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ALL GOOD,, found it,,, ;D
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Got a bit more done today,
bored the cylinder and faced off the valve ports
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ALL GOOD,, found it,,, ;D
Stuarts are good at hiding dimensions on their drawings ::)
Jo
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yes, looking good. Regarding the comment on rough castings perhaps undersized, I'm curious where you bought the castings from. I keep hearing tales of unscrupulous vendors use OEM castings as patterns....did they come from Stuart or could that be the issue?
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Looking good Warren :ThumbsUp: I'm following along with interest as I'm attempting something similar.
I was surprised to see in your castings the box bed and soleplate are a single casting, I bought a casting kit for a 10v on ebay recently and mine is in 2 parts although it looks to be a recent kit.
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Turned the cylinder end caps today and all went smoothly so onto the valve chest.
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Ever had one of those days when you you just shouldn't have gone into the work shop.
First I broke a $30 solid carbide end mill, and then this..... :embarassed: :'(
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Looking good Warren :ThumbsUp: I'm following along with interest as I'm attempting something similar.
I was surprised to see in your castings the box bed and soleplate are a single casting, I bought a casting kit for a 10v on ebay recently and mine is in 2 parts although it looks to be a recent kit.
Yes the castings came direct from Stuart. I also have a #4 part set of casting I picked up at a flea market. They are dated from 1977. They are FAR Superior to the #7 I have purchased for this build .
You can probably see in the pic above the casting for the valve chest has a lot of porosity up around where it broke.
Also you will notice when I drilled the through hole for the valve rod up into the dome it wandered off center slightly. Any tips on how to stop this happening. I may go and buy a new drill bit. MB that will help.
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Buy a tube of JBWeld from Ramon :Lol:
Best fix will be to mill the top edge flat and open the hole out to say 3/16" then make a dummy end bush with a 5/32" spigot that fits down the hole and drilled for the end of teh valve rod. These bushes are gland shaped and retained by two small screws so you can assemble and get it into a position where the rod moves freely hence the larger hole than spigot and then spot the hole positions for the screws. make the bush blind as it is not worth adding glands on such a small size part.
To avoid the problem next time make sure the inner face has been cleaned up so the drill starts on a flat surface and the use of a long series center drill will help a lot.
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Does this valve rod hole/guide actually do much to affect performance on small engines ? Presumably the inward steam / air pressure will seat the valve adequately?
The casting I have for a no4 engine doesn't have the cast protrusion although there may be sufficient thickness in the valve chest wall to drill into. (I haven't got that far yet so haven't properly looked into it)
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I spat the dummy with the old part and started afresh. MB when I get the urge I will go back and repair it the way you suggested Jason. Thanks for the tip.
Here is new valve chest from scratch and the cover.
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Yes the castings came direct from Stuart. I also have a #4 part set of casting I picked up at a flea market. They are dated from 1977. They are FAR Superior to the #7 I have purchased for this build .
The old style 10v trunk guide I was given is far superior to the modern set of castings I recently bought, it also has a better profile. (the old one is on the right)
(https://farm1.staticflickr.com/906/28320952848_7d0127b27e_z.jpg) (https://flic.kr/p/K9ChAu)
(https://farm1.staticflickr.com/904/28320969498_a15f7f33f7_z.jpg) (https://flic.kr/p/K9Cnxy)
I'll be interested to compare the two after machining.
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It looks like the old style has much better support for the Cylinder with larger braces.
Larry
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If that is a genuine Stuart one it must be over 35yrs old as the one I made in my teens has the same taper as the "new" one in your photo
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It's the one Jo gave me so I don't know anything about its origin
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Does this valve rod hole/guide actually do much to affect performance on small engines ?
The valve rod needs guiding at the tail end to stop it waggling about in the stuffing box, making it wear quickly and therefore hard to keep steam tight.
The more complicated alternative is an externally guided valve crosshead. In full size you often have both so that the gland is not required to support the rod at all and can float.
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Bit more done today,
The alignment shaft is an extremely useful item for aligning the bearings Standard and cylinder. :cartwheel:
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I have no idea how to cut the radius shown on the drawing in the end of the crosshead.... :headscratch: :headscratch:
I'm guessing I need to grind a rounded trepanning tool....
Here is my half hearted attempt using a DCMT insert. :facepalm:
Any suggestions would b appreciated thanks..
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Triangular file will have it done faster than you can make a bit and set it up for the cut. But It won't put back the bi of metal you did not need to remove.
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AH ... yes,, I see what u mean. It seems I have created a difficult situation for myself. A tri file will be little use to me now with what I have done.. :Doh:
Oh well. Its a custom cut cross head. 8)
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OK.... it seems I have fooked up BAD this time.... :help: :help: :help:
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I basically tried every which way to stuff this piece up. and finally I did, second last operation and it grabbed whilst trying to drill the pin hole.
I don't think this is fixable.... :facepalm:
My biggest problem I think is not having the correct "order of operations",, which I am finding out is critical with these types of parts that have so many operations per piece.
Would any body be so kind as to list them for me please for this part. ...I am gutted !
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I'll leave the method to one of the casting fans.
You could save the bottom half and make a top from steel. If you cut off the rod about 6-8mm above the bearing it can be drilled out and tapped to take a new forked rod. Or cut it off flush and make a steel one with a flanged end which is more prototypical of a marine conrod. Either way you won't have to contend with soft gunmetal.
(http://img.photobucket.com/albums/v156/jasonballamy/Engineering/Vertical%2024/DSC02753_zpspl4w9afp.jpg)
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OK.. so. after some judicious panel beating ... and a little end bushing. we r back on track... ;D
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nice save !
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Glad you could save it Warren, I am just catching up on your progress so far.
Bill
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Ouch. But the fix looks good!
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Thanks guys,,
Now I have ANOTHER problem.
Going by the dimensions on the drawings the groove in the piston should be 13/16 in diamater, and the piston is 1" dia.
At 13/16" dia for the groove though,, the piston will not go in the cylinder with the O ring fitted. The OD of the ring fitted on the piston measures 1 and1/8". That's like 3mm oversize.
No wonder it wont go in. I tried the zip tie trick, I also have a healthy lead in chamfer on the bottom of the cylinder.. SO, in desperation I deepened the ring groove by 40 thou !!!
I can now get the piston to slide into the bore with a bit of effort. But then it jambs tight. I can feel metal on metal, as if the piston is rubbing on the bore. It certainly is not a nice slide fit like I was expecting.
The bore is 2 though over size and the piston is a half though under,, so there should b perfect clearance.
I then attached the cylinder and piston rod to the cross head in the standard, thinking that might help hold it all in alignment and square, but no go.... still grabs and binds like crazy... ANY THOUGHTS.. :help: :help:
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How much width did you allow on the groove so that the ring could be compressed?
Assuming a nominal 3/32" section ring which is actual 0.103". for a model piston you want a groove depth of 0.098" but the width needs to be 0.125"
If it is 1/8" nominal which your 3mm oversize suggests then they are actually 0.139" section and groove should be 0.132" deep x 0.188" wide.
Note groove depth is calculated from cylinder wall so you will want to be about 1 thou less
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thanks for the groove specs Jason.
Stuart must have changed O ring wall thickness without altering the drawing cause it was NEVER gonna go the way it was.
Just a bit more progress...
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I double sided taped the chest to the cylinder block.
Stuart decided to give me 5ba studs and nuts enstead of 7ba :facepalm: :stickpoke:
So the socket head cap screws will have to do for now on the cylinder cap...
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getting there
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came across this at boot sale.. 2nd hand but never used.. $150 :ROFL:
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Needs a palette to b useful... so here goes. I knew I had been saving this piece of Aluminium for something
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Hopefully it will look this in a few days....
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As your hole pattern follows the 3 slots would tee nuts and studs not have been more versatile? That is all I use on mine.
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HA.... U got me AGAIN... :hammerbash: (I can't believe I didn't see that)
OK smarty; I'm gonna go and change the hole pattern so it actually sort of makes it worth having... :lolb:
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I have patterns of drilled holes on a plate on the rotary bed of the BCA and I find them very good. There are tee slots underneath the plate but I have never felt the need to take the plate off :)
Jo
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Ummm... forgive my dumminess... but what exactly is a BCA..?? :headscratch:
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Ummm... forgive my dumminess... but what exactly is a BCA..?? :headscratch:
A type of instrument maker's jig borer :)
Jo
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Thanks Jo, I was ignorant of that fact too :-[ Terry
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Hey guys,
I have a couple of tech questions for you,,
1/ On this engine at TDC should the piston cover the ports in the cylinder liner at all? On my engine the piston covers the port by app half, or a bit less.
2/ The drawings specifically show 9/64" (3.6mm) throw on the eccentric. For a 1" piston stroke I thought the eccentric would have a half inch throw. :headscratch:
thanks in advance
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for the eccentric this is for the valve travel the piston travel is the crank shaft.
it is fine if the piston partly covers the port as long as the rings don't drop into the port for cars iron rings the ring can partly go over the edge .I usually have a counter bore for the cylinder cover location with o taper lead to the
bore ,the edge of the ring can over lap the edge.
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Thanks John,,
yes I am aware the piston stroke is controlled by the crank throw. Also that the eccentric offset throw controls the amount of valve travel.
However isn't it generally the case that the eccentric throw is half the piston stroke to allow for the correct valve travel in each direction,, or have I got it wrong somewhere along the line. :thinking:
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the valve travel is determined by the steam port and the amount of lap and port opening independent of the piston stroke it is determined of valve events.
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As said the stroke of the piston is not related to the stroke of the valve, as an example that vertical I recently made is about the same size as a No7 @ 24mm bore x 24mm stroke yet the throw of the eccentric is only 3mm so 25% of the piston stroke. And the longer stroke Thompstone only has 2.5mm eccentric throw for 46mm piston stroke so only 11%
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Warren, if you look on any steam engine in action you will see the eccentric throw is usually considerably less than the crank throw.
https://www.youtube.com/watch?v=Za00In-g5RE
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:facepalm:
Thanks guys; yes the penny has dropped.. I now see what John was trying to get through to me.
On that video it clearly shows what is a minute port spacing it must have compared to the piston stroke.
Next question, why do some engines for the same given bore diameter have MUCH longer strokes?
I know in petrol engines it has something to do with torque; is it the same for steam.
Is there a good book I can buy that can teach me all this stuff.
Thanks again for all your help. :praise2:
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Started work on the eccentric sheath today.
After the debacle with the con rod; I decided not to take any chances with this one and bolted it down to a slab of aluminium and pinned it with some very small roll pins as well. Luckily the hole for the eccentric was cast with a nice taper in it so a washer was perfect to wedge down in the bore and lock it down tight with a 5mm flat head bolt.
First time I have used a rotary table. I have to figure out a way to eliminate the dwell marks. Was pretty hard jumping up and over and back down the darn rod part. :wallbang:
Other than that I am pretty happy with it so far.
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still following you are making great progress.To remove the dwell marks i usually take finish cut ,or repeat at the same setting .No more than .1mm .its a finish cut to remove any spring in the tool or looseness in spindle.
For the hole try removing the rake angle on the drill.Will reduce the tendency to grab,this only needs to be a small flate hone stone can be sufficient or a little bigger on the grinder. the flate only needs to be small to make a difference.
yes longer stroke more torque tend to be slower short stoke less torque but suited for higher speeds.
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Interesting article about Stuart Turner (http://modelengineeringwebsite.com/Stuart_Turner_Romance.html) on David carpenter's site last week, mentions that when the No7 (not 7A) was first introduced they shipped over a ton of castings in the first month and I think then they were only casting sets not all materials as well.
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starting to get the hang of using a rotary table..
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The eccentric turned out perfect first time... more ass than skill.. :lolb:
The valve rod linkage was just to small in my big four jaw soo... a seven jaw chuck was the answer
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Oops.. wrong pic.. :(
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All mounted up..
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I am gonna have an awful lot of polishing to do after I get this baby up and running
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IT RUNS.... :cartwheel:
It will sit and pur at about 55rpm like a swiss watch. I am stoked. Still need to put the cylinder cover on yet and fit the exhaust.
I tried to upload a video but even 10 sec is like 20 MB. Any tips on how to do that?
Thanks for all your help guys. :ThumbsUp:
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Here's a pic till I figure out how to do the video thing
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Great news she's running :)
Waiting patiently for the video... Don't take too long :stickpoke:
Jo
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Well Done
Easiest option is to load the video onto You-Tube and then paste the link here
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OK, I'm trying lol... :wallbang:
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My son posted it up for me as I almost threw threw the computer after cont failing... :cussing:
Here is link
https://www.youtube.com/watch?v=vVItrVwEcf0
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Second run.. :pinkelephant:
https://www.youtube.com/watch?v=yUdlu-2Krow
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And yes I know... I can't spell for $hit.. :lolb:
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That's running very nicely in the second video, did you make a slight adjustment to the valve position as it have a more equal up and down stroke.
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Thanks Jason. yes in the second video I advanced the timing slightly to open earlier.
Funny thing is I didn't really think it would run as I still haven't fitted the glands to the piston rod or the valve rod.
Both were reamed though, so I guess that was good enough for it to run at least. I will tidy up a few loose ends now that I know it's a goer.
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Very smooth runner, excellent!
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Congratulations! That looks great! You have a right to feel proud of that!
Kim
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Love seeing the pink elephant!
Nice job. Congrats!
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Nice runner 8)
Love seeing the pink elephant!
Just don't show him your castings :hellno:
Jo
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nice runner .
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:ThumbsUp:Nice! Well done
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Very very nice. I would love to hear it running on the “hot stuff” .
Cletus
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great to see you have it running good work
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Love that sound - runs great !
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WOW, thanks guys, didn't realize so many were watching from the sidelines.
Can u believe it runs that slow and consistent WITHOUT the flywheel even!
I will finish off the little items and give it a coat of paint and a serious polish.
Would I build another Stuart kit; in a word.... NO
That's really a personal decision based on cost though rather than the minor quality problems with the castings.
This model cost me 520 AU dollars landed. That's like 2 days pay or more for most people over here! I certainly cant justify that again on such a small engine.
Trouble is the castings available in Auz are so limited. Could b bar stock time, but I'm not sure I have the capabilities or confidence just yet.
Besides I DO love the ME Beam engine at Reeves.... ;D
or the Muncaster joy valve engine... or the Monitor...
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Have you looked at Winter's offerings, that is where JL got his current project castings from.
http://www.ejwinter.com.au/images/E%20J%20Winter%20ME%20Supplies%20Catalogue%202017.pdf
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Would I build another Stuart kit; in a word.... NO
That's really a personal decision based on cost though rather than the minor quality problems with the castings.
This model cost me 520 AU dollars landed. That's like 2 days pay or more for most people over here! I certainly cant justify that again on such a small engine.
Trouble is the castings available in Auz are so limited. Could b bar stock time, but I'm not sure I have the capabilities or confidence just yet.
Besides I DO love the ME Beam engine at Reeves.... ;D
or the Muncaster joy valve engine... or the Monitor...
Try Blackgates: http://www.blackgates.co.uk/ for good value casting sets :embarassed: Their Clarkson steeple is good value for money :o http://www.blackgates.co.uk/Clarksons_Catalogue.pdf
Jo
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Thanks for the links guys... So many choices.
For the moment I can't stop playing with this one. It is mesmerizing. :insane: :insane:
https://www.youtube.com/watch?v=nZJOaX3i3lQ
It has run in really well.
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didn't you say earlier that you had other castings as well ,are you going to build them .
this one looks good.
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Quite right John; I do have a part casting set for a number 4. But lets face it, it's pretty much the same thing... just a bit bigger. I want something that looks different to a vertical for my next project.
I am leaning towards a scratch built bar stock twin horizontal. :facepalm: LOL
Have started the drawings already.
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Great stuff Warren, well done :ThumbsUp:
Have you got the means to run it on the hot stuff ?
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Great stuff Warren, well done :ThumbsUp:
Have you got the means to run it on the hot stuff ?
Thanks Gasmantle;
No steam sadly,, :'(
I am looking at a PM research boiler as they seem good quality and reasonably priced.
Gonna have to sell some other toys first to keep the missus happy. ( I have a damn lot of toys) 66 HO scale locomotives brand new in their boxes for instance. I have collected them over the last 20 years.
But it looks like I will never have a model train room as the wife won't give up her side of the garage.. no matter how hard I coerce. :hammerbash: So there going on fleabay soon to fund my new hobby :cartwheel:
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This is just my Kato collection... I have almost twice as many Athearn as well! :facepalm:
Any one want to buy a HO scale locomotive... will swap for model steam engine.. LOL
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I am looking at a PM research boiler as they seem good quality and reasonably priced.
I'm not sure if you are in the UK or not but over here the Stuart 500 series (500, 501, 504) often crop up on ebay and seem to be a well respected design