Building a 31/2" Gauge Locomotive Engine

[kvom]

I'm getting to the point when the chickens come home to roost.

I know just that feeling as that's where I am with my build.     No worries!  Looks great! 

[shoey51]

Im picking the loco up next weekend so no pictures till then Im afraid

Er..... Graham? 

Graham!! 

Don`t you think these good people have waited long enough, to see what I`ve seen? 

Perhapse, not on Stew`s posting though........   

David D

Here you go David and for any one else thats interested

http://madmodder.net/index.php?topic=1447.0#new

[sbwhart]

Well I've bitten the bullet and a few days ago I started assembling the valve gear.

Its quite a fiddly little job with lots of small fasteners to do and undo, and its one of those jobs you just can't rush.

Any way first thing I did was to strip the wheels off the frame.



Ther's lots of little bits you have to carfuly put away and label.

When doing thes jobs you realy apreciate the assembly frame, that allows you to turn the loco through 360 deg, so you can move it about to gain access to bits, the one I'm using I made myselve, I'd seen a number of frames in use and I just came up with a design that suited the bits I'd got, I used some ally angle, box section, some 10mm studding, and bit of steel and wood and cap screws.

This is a close up of one of the pillars.



One problem from not using a casting for the cylinders was that the square section fouled the leading wheel horn block, to get round this I just milled a chamfer on the cylinders. Note the use of a ball race ring used as a parallel.



The cylinders are positioned 1" from the buffer beam and 5/16" from the top of the frame, it was carfully put in position and a big clamp put over the frame whilts the clamping hole positions were spotted through the fram with a hand drill. The cylinder was then transfered to the mill and the holes drilled in the side of the cylinder taking care not to drill through into the bore.



To keep them nice and square the holes were tapped 5 BA using the stand. Note the valves port faces are protected with masking tape.


 

The motion frame was assembled using the same technique (no pics forgot)

This is the asembly so far next job the valve linkage.



Having fun

Stew

[Divided he ad]

Looking good Stew..... Glad you're taking the time to explain a few of the bits 


 







Ralph.

[Stilldrillin]

Stew,
That`s looking very complicated!

You might be having fun...... I`m holding me breath! 

Hope it keeps on developing successfully for you...... 

David D

[zeusrekning]

WOW man, Now this is a deep project. I just scanned all the pics, but this is definitely on my must read list.

[shoey51]

Stew that is great progress so far 
I have slowed on my O gauge will have to get on with it again soon

[John Hill]

Oh dear!  Stew you make me feel so inadequate!

It seems in the time I have spent on my little engine you have built half a locomotive!

[NickG]

Looks like it's going well Stew. It's amazing to think that this thing will be puffing around merrily pulling a few passengers!

[sbwhart]

Well I've spent a fiddly couple of days trying to assemble the linkage into the loco frame its a bit like knitting steel.

The drawings a write are are a bit fague as to how to fit it together it just say use BA fixing, all the holes are 1/8 so I used M3 threads as I have a supply of self loc M3 nuts, but as I started to get thing together I realised there wasn't enough room to fit nuts, all the pivot pins would have to loctited in place, a job I will leave untill last.

This is the assembly from the top



And from below



I tried turning it over by hand but everything loced up, I fiddled about a bit and it still loced up, fidled a bit more still loced.

So went for me tea and a think 

I havn't set the timing I think thats the problem and I havn't connected the valves rods so tomorrow that what I'll do and have another go.

wish me luck

Stew

[Stilldrillin]

Stew,
I hate ordinary jigsaw puzzles........ 

Here`s wishing you the very best of good luck with yours! 

David D

[bogstandard]

If you are still having trouble Stew, a new pair of eyes and hands are available if you need it.

Sometimes you can't see the forest for all the trees.

That is coming along just wonderful.

Bogs

[sbwhart]

Thanks Chaps

John

Thanks for the offer for a second pair of eyes:- I've slept on the problem, the basic action of the linkage seems to be doing what it should. I think the problem comes from two areas:- I haven't set the eccentric timing correct it all over the place, and I haven't connected up the reversing rod I think it needs this to ancore the motion.

I've stripped it down made the gaskets and started to fit the studding for the valve chest, I'll put it all together getting all the pins to the correct length and fix them with loctite, and then see how it goes:- (there should be a finger cross smiley for times like this)

I may be calling on you if I'm still in trouble.

I'm nipping over to Macmodels tomorrow for some more studding is there anything you would like me to pick up for you.

Cheers

Stew

[bogstandard]

Nothing needed Stew, I have everything for the project I am on now.

Thanks anyway.

John

[CrewCab]

That is looking impressive Stew, good luck but I'm sure you'll sort it ..................... we're all watching and waiting with fingers crossed for you 

CC

[Bernd]

Sure looks like a tight fit with all those parts in there.

Would like to see that in motion. Nice work Stew.

Bernd

[sbwhart]

Well this has been a good and bad day

Made the gaskets for the cylinders using the gasket material John gave me:- thanks John

This is the gasket for one of the cylinder covers



Then spent some time fixing the studding to hold the valve chest in place but ran out of 6BA studding   Ok so I've got to go to Macmoddels today to get some along with some other bits a pieces. When I told the Boss I was planning on going to Macclesfield she said:- " ho ther's a good furniture shop in Macclesfield I'll come with you and we can look for new sofa and chairs"

 ££££££££££££ Translation $$$$$$$$$$$


Dam Dam Dam,

Any way assembled all the linkage sorting out the pins etc, quite happy with the results and fairly confident that it will work.

As you can't see it very well when its inbetween the frames this is it.



Then desaster I placed it up against the cylinder to see how it lined up with the valve rods.



Spot the deliberate mistake:-

I've off set the arms 1/8" too much.   don't know how I did this probably measured from the wrong point.

So option for putting it right 1:- Re bend them 2:- Re make.

I think I go for option 2 it wont take too long and I was not too happy with result from bending the crank method, I think I'll fabricate them up using a different method.

My scrap collection is growing

Still having fun

Stew

[bogstandard]

What's the fun in having everything fitting perfectly every time Stew?

It is little things like that which remind us all that we are only human.

John

[28ten]

I'v just read right through this, really good stuff. I like the way you have made the crossheads, I think it would translate to a smaller scale, so if i get some milling capability I will try it.
I am intrigued at the way you fitted the hornblocks and them made the rods to fit. In small scale the accepted method is to make the rods first and to use them as a jig for setting the hornblocks.
Anyway good stuff, I wish i had the ability to do something similar myself

[sbwhart]

I am intrigued at the way you fitted the hornblocks and them made the rods to fit. In small scale the accepted method is to make the rods first and to use them as a jig for setting the hornblocks.

Thanks for your encouragement Chaps

Hi 28ten

By rods I take it you mean bearing blocks.

I just followed the recommended way from books for fitting the hornblocks and bearings for this scale, the critical feature is getting everything square and in line, in smaller scales this must be as equally important, but I guess the smaller size allows you to use different methods.

I was really pleased how that method for making the cross head worked out, everything fitted together without any fettling, I just thought it would be a better method to those recommended in books so I tried it: a lot of the literature on building locos dates from the 1960 - 70, so I think it was written around what kit was available in the average workshop then, we've moved on since then.

Thanks again for you input

Have fun

Stew

 

[NickG]

Well done Stew,

That is looking mighty complex! 

Nick

[sbwhart]

I thought I'd give a bit of an update on the remake of the rocker arms, as I'll be short on shop time for the next week.  ,

I originally toyed with the idea of making the rockers out of one piece instead of fabricating them, for the remake I went for the one piece option. The most suitable material I had in my stash was from a garage door (thanks Ralph  )

First job cut a chunk out with an hacksaw:- cutting on the forward stroke helped along with a bit of oil.



After half an hour and a sore arm this is what I got



Roughed to size in the mill :- Bloody tough stuff Ralph blunted two cutters 

Note crib sheet to help keep things on track.



A bit of milling and drilling and filing and job complete. Note the difference with the first attempt made to drawing the second attempt may look different but all the critical features are correct and fit for purpose.

Any one who,s worked in a design office will tell you one of the most important things is to recognise the functions and importance of each feature:- Critical to function, Safety critical, Critical to appearance, Minor to function, Minor to appearance etc etc



I seemed to have spent an age assembling and unassembling things the cylinder is held together with 60, 6 ba and
 7 ba screws and washers, I've been busy with not a lot to show for my activity, any way I've packed the pistons and glands with PTFE packing and assembled the cylinder into the frame so that I can measure up for the reversing linkage which will be the last thing to fit before I set the timing and give it a try. As for setting the timing I've no idea how to do it I'm going do a bit of reading about it first and then have a go.

This is the assembly so far



Have fun

Stew

[Darren]

You know something Stew...

Your arms didn't look that big to me....all this sawing and filing we should be calling you Popeye......


maybe I'm just lazy....


Very nice work, as usual......

[Divided he ad]

Nice Job Stew 


Them there black arms are mighty strong stuff alright, they are what I used to make my ball turners tool posts from 


They are a very nice shape and would appear to me to have the benefit of a wider bearing section to spread the load, thus helping to reduce wear, I think 
(with a good helping of oil etc obviously)


Really looking forward to the running tests 





Ralph.

[sbwhart]

Setting the valve timing

 

I guess that just about says it.

I've been trying to set the timing for nearly two weeks now, along the way I've put few things right:- catching pins: Valve chest drawing error that lost me 1/8" of throw: Reversing arm slipping: Eccentrics slipping, etc etc etc, but I just can't seem to get it right, I've read and re read the build manual tried putting a different interpretation on what it mean by forward dead centre and back dead centre:- checked things: eccentric throw, length of arms, action of reverser etc etc, but I just can't to get working or get things to stay put, one minute thing turn over nice then it jams up and throws thing out.

I'm sitting writing this with a can of draft GUINESS  to drown my sorrows. 

Decided to put it to one side for a few days, and then go back to stage one strip it down and carefully build it up again checking everything out.

Down but not beaten

Stew