Building a 31/2" Gauge Locomotive Engine

[sbwhart]

My suggestion would be to do a bit of manual hacksawing thru a 6" bar of cast steel, that just might knock that damned smile off your face.


Bogs

Why would I do that when I know a man with a powered haxsaw   

Thanks for your kind comments gents much appreciated.

Stew

[sbwhart]

Been busey this week fitting the slide bars to the cylinder.

I was unable to spend as much time as I hoped what with work demands and my old Dad strugling with the heat, and needing a little bit more looking after than normal.

Any way this is what I've been up to.

Cut the cylinder head studs off to length using Johns tip of putting two washers under the nut, cutting the stud off to this, cleaning the cut end off, and removing one washer, this leaves all the studs standing out all the same length, all very neat, the cylinder heads at the other end are held down with 7BA countersunk sloted screws a bit more easy to deal with, but still very fiddly.

I also made the slide bars from 1/8" thick gauge plate, quite a simple little job, sorry no pics.

The next job was one that's been troubling me for some time:- the slide bars are held onto the end of the cylinder heads with 7BA screws, for this the covers have a 3/4" across the width flats, that need to be concentric with the centre line of the cylinder.

When you read old Curley's instruction: he makes this sound deceptivly simple, he basicaly recomends making up what is in effect a filing button, 3/4" wide that you centre up on the bores and file the flat working to this, describing the fit as a nice slide. This is where I have problems what's one mans nice slide fit is anothers tight fit, its very dificult describing touch fits to another person, in industry we get around this by very well specified limits, fits and tolerances, but in a home maching environment you can't do this, it very much depends on the individuals skill and experience.

To make this even worse there is no easy datum to work off, so I decided that I would have to create my own Datum.

I fixed the cylinder complete with pistons and covers in my vice, and with my height gauge did some carfull measuring.



I then did some calculation and work out a setting height that I made up with slip gauges  (I convert the answer to imperial as my slips are imperial so don't be confused)



I then brought the cutter down  (no power) to touch on this pile of slip and zeroed the DRO.



I then milled the flats on one side down to the DRO zero:- flipped the cylinder over repeated the measurements and calculation for this side and machined down to the zero.



I was very pleased with the result the flat was 0.756:-  .006 big but I can compensate for this with the mating part but I still don't know if its simetrical arround the centre line, to do this I need to fit the slide bars.

Drilling the tapping size for 7BA  this was done on the centre line of the cylinder picked up from the piston rod.



Tapping 7BA on tapping stand nice a square



Now fitting the slide bars I was able to check symetry by measuring the gap each side between the piston rod and the bar, it was within 0.003"

 

 

I think I can live with that



This is the slide bars with the motion frame which they will be fastend to eventualy with a 3/4" slip gauge which moves up and down the gap lovely.

Next job is the cross head (big end) I'm going to try and do this using the RT so it should prove interesting.

Cheers

 

Stew

[sbwhart]

My Boss because of the hot weather hasn't slept too well, beging very restless, this in turn has agrivated her bad back, as a consequence she's spent the best part of today resting, so that I don't disturb her I've spent a fair bit of time in the shop:- well thats my excuse any way 

So got a fair bit done on the cross head.

This it



In the build instructions Curly calls for it to be made from mild steel section, machined in the lathe four jaw and the vertical milling slide. Most of Curley's designs were done between 1920 to 1960, so he was writing for a very different bunch of medel engineers than today, they'd give their right arm for some of the kit we've got. So it seemed OK to me, to take advantage of some of my kit and try to make it, to my way of thinking  , a more accurate and easyer method:- so what I'm going to do is use the Rotary Table.

Starting off with a bit of 30mm diameter mild steel bar, turn it down to a diameter eaqual to the hypotenuse (Mr Pythagorus again) with a groove to give datum points for each Cross head.



Drill full length roughing drill I'll finish drill when I've done with the milling

Transfer the bar in the chuck over too the RT set up Horizontaly in the mill.



Note use of centre support.

Check for squareness sideways



Check the other way, Note stylus on DTI you can do this on this type



Rough mill out one side (1/2 mm from size)




I'll drill and mill the cross holes whilst it still got plenty of meat on the underside.



Slot drill out the 12mm steped holes:- my little mill grumbled at this but it copped.



Check on depth with home made depth gauge as I couldn't get in with the vernier.



So thats it for know so far so good we'll see how the rest goes another time.


 

Stew

[Darren]

Stew you are really motoring on with this aren't you..looks like a very "engineered" bit of work there.
As always following with keen interest.....

[Stilldrillin]

Stew you are really motoring on with this aren't you..looks like a very "engineered" bit of work there.
As always following with keen interest.....

Me too!
Just like what he said.......  

I was going to say "professional".  


David D

[bogstandard]

Careful with the compliments lads, he has only got a narrow doorway on his shop, and we don't want him getting stuck.

Very nice work BTW Stew, I bet you are praying for bad back trouble again tomorrow.

Every time I tried to start something over the last couple of weeks, all I get is a demented German asking where are we going today. I think the wife has used up every route to Morrison's supermarket, and I think he will catch up sometime soon and realise she is taking him to the same place every day.

Use any excuse you can to get in your shop, as once you retire Stew, she will have jobs backed up for you to do while she is still at work.

Bogs

BTW, parting was perfect, many thanks.

[sbwhart]

BTW, parting was perfect, many thanks.

As the immortal bard said "parting is such sweet sorry"  he'd obviously not tried sandvik 



Ho the wit of the man

Ok I'm going

Stew

[shoey51]

Great work Stew 
 I am watching this thread with keen interest as it is giving we ideas on how to use my machines to the best of my abilities.
Ive had a bit of a setback with my build
cheers Graham

[Stilldrillin]

Great work Stew 
 I am watching this thread with keen interest as it is giving we ideas on how to use my machines to the best of my abilities.
Ive had a bit of a setback with my build
cheers Graham

You`ve had a setback Graham? Are you sure? 

I wouldn`t call 7 1/4" gauge a setback.......  More of a slight diversion. 

Ooops!         Me an me big gob........   

Sorry Graham........ 

David D

[sbwhart]

Thanks Chaps

Bin up early and in this shop this morning.

Finished the cross holes in the second head but this time I took a bit of the load off the mill by putting a smaller slot drill down before the finisher.



Then indexed the RT round 180 deg to do the other side, at this point I nearly had a disaster when the mill started to cut different depths it seemed to have a mind of its own then I spotted that the winding handle was catching the centre steady, so just took the handle off problem solved.



With the finish cut I indexed round to the first side took a light cut, indexed round to second side and took the same cut off, keeping things nice and symetrical.

Then Indexed 90 deg to mill the thin edge to correct width not so much to come off with this, again indexing round with the same cut to keep thing symetrical.



At this point I came up against a stopper I need a 3/16" slot drill or end mill I've got 5mm, 4mm, 4.5mm but no 3/16" 

if I'd have known I could have adjusted the width of the slide bars to suite a 5 mm end mill, I must learn to check that I've got the correct tools to finish the job.

John do you have a 3/16 slot or end mill I could borrow.

Cheers

Stew
 

[sbwhart]

Great work Stew 
 I am watching this thread with keen interest as it is giving we ideas on how to use my machines to the best of my abilities.
Ive had a bit of a setback with my build
cheers Graham

The thing with set backs Graham is you've just got to bounce back from them, we've all got big scrap boxes, it some time pays to put the job aside and get on with something else and have a good think where it went wrong, then pick it up and start again, the second time round it just clicks, and its completed in no time with no drama. Thats part off the fun in this game bouncing back

 


7 1/4 " What's that all about then 

Have fun and good luck

Stew

[shoey51]

Stew thanks for your advice mate will take it on board
and David is right there is a slight diversion I bought a loco at a price I couldnt resist. the loco runs on 7 1/4 gauge track but it wont stop me finishing my loco project

[bogstandard]

I know I have what you want Stew, call round anytime and we will have a root, still not sorted all my cutters out yet.

I was hoping to get them done today, except for you know who.


John

[sbwhart]

Stew thanks for your advice mate will take it on board
and David is right there is a slight diversion I bought a loco at a price I couldnt resist. the loco runs on 7 1/4 gauge track but it wont stop me finishing my loco project

Its a pleasure Graham, its nice to know it helps other people with their projects when you post your work.

That loco sounds real interesting most gauges in the UK are either 2 1/2" - 3 1/2" or 5" but the larger gauges are now starting to get very popular I know of a couple of 7 1/4" tracks that have opened up near us.

A pic of the loco would be nice 


Cheers

Stew

[shoey51]

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

[Brass_Machine]

Stew...

As always, nice work so far. Feels like I am there watching this build go on.   

Eric

[sbwhart]

With the loan of the 3/16" slot drill from John I've been able to finish off the cross head so this is how it went.

To avoid the milling holder crashing into the chuck I had to extend the cutter out from the holder I've got a selection of holders suitable for unthreaded cutters (FC3 type) so I used one of these:- ther's one in this picture.



It was a matter of taking a cut along the cross heads, rotating 180 taking the same cut and measuring the width across the slide bars until I got it to 1"



I got it to within .005" and called it a day.

Next the chuck was removed from the RT with the work still held in it and remounted on the lathe.

The through hole was finished off to size, and the small boss turned, and then they were parted off from the bar.



I then made up a soft filing button to act like a nut and bolt and the two cross heads bolted together back to back.

Drilled right through both 1/8".



Milled out some of the meat.



Then filed the rest out till it looked OK. Her they are with the button.



And separated



Then the pin was turned up out of silver steel

And this is how it all fits together



I was really pleased how using the RT to make the cross head turned out, when I fitting them to the slide bar in the cylinder the piston rod should line up with the through hole in the cross head I was expecting to have to do a bit of fitting and packing, and  but no they lined up perfectly.

 
 
Have fun

Stew

[shoey51]

wow Stew that was great work there mate

[Darren]

Stew, I can see that I'm going to have to take a trip to yours just to see this when it's finished...

[sbwhart]

Thanks Chaps

I've just done a bite of a stock take on bits to make before I start assembling to the frame and its zero,

I've not been looking forward to this:- I'm getting to the point when the chickens come home to roost.
 


Stew

[bogstandard]

Nice slick machining there Stew, you've certainly got the swapping over between machines sorted now.

Never be afraid to go forwards, I am sure that when it is all fitted to the frame, things will go smoothly, and you will wonder what all the worrying was about.

Even if it doesn't go to plan, I am sure a man of you calibre will soon have it sorted.

John

[NickG]

That looks great Stew, those parts are far too complex for me. Just catching up after been off for 2 weeks moving house etc. Still no internet at home yet, was disgusted to find it'll take the ISP 17 days to flick a couple of switches and send out the odd letter!

Good luck with the assembly.

I don't think I'll be active in the workshop for a while, it almost brings me to  it's a double garage and used to be a show house so it's plastered out and has a radiator in it, however, the problem is i can't get into it as everything is just dumped whilst "priorities" lie with the house and garden apparantly!

Nick

[sbwhart]

Hi Nick

I was wondering where you were, sent you a work email but it went to Mike of the same name    I must have done it before as he asked me how I was doing with my new mill 

I wanted to ask how the cross head pin in your loco was assembled    I've followed the drawing but some how it doesn't seem quite right.

Sounds like you've got the makings of a nice shop when you've got the tribe settled in.

Have fun

Stew

[Stilldrillin]

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

[NickG]

Stew,  quite funny that Mike remembered what the conversation was about!

I will try to have a look for you tonight. Mabel is one of the few things I can get to, I put it on the floor on some laminate flooring underlay for my 3 year old son to play with while I tear old shelves down and the like! He won't leave it alone, he's been sat on the tender, losing bits etc. (luckily found them now) - I keep telling him we just need to tidy the garage , fix the loco then it'll work .. he just says "we will tidy the garage now daddy"!

Anyway, looks like Mabel is the first job when the garage is sorted now. I'm going to completely strip it down as none of the chassis is painted.

Will try to check the cross head pin tonight although I'm not sure I'll be able to see much will it come out without taking loads of other bits and pieces off first?

Nick