Minnie traction engine build

[George JervisParticipant @georgejervis86082]

Hi everyone

I'm starting on my first ever proper build so please be patient if I have any silly questions. I've owned my lathe a little John mk2 for about 3 or 4 years now, a part from doing odd jobs etc I haven't really built anything like this before, so I'm looking forward to this adventure.

I have brought the casting and all the instructions/Manuel and plans, book and everything I need for the build a "Minnie traction engine", the boiler has already been made and has a test certificate for it but I've stumbled at the first hurdle I've been trying to figure out how to fit the horn plates to it would anyone have any suggestions? (Please look in my album) Is it okay to drill through the stays and tap them so they can be bolted on?

Many thanks

George

[George JervisParticipant @georgejervis86082]

Minnie traction engine build

[JasonBModerator @jasonb]

Usual method is to set the boiler up on your mill table laying on it's side so that the barrel is parallel to the table and sides of boiler as true as you can get them. Take a skim cut off the five hexagonal stays until they are 1/16" above the surface of the barrel. Then turn the boiler over with the newly machined stays on the table and skim the other side. You should now have two true surfaces.

Make up the horn plates with 4BA clearance holes then set the boiler to stand true on a flat surface, offer up a hornplate getting the front/back and vertical position correct and spot through one hole. Drill and tap this hole for 4BA and then set the boiler up again with the hornplate held on by a screw in that first hole and then repeat spotting an opposite hole, tap and setup again. You should now be able to do the remaining 3 hole sin one go. Then repeat it all again for the other side.

You can do it as above with single hornplates or you can do them together by making up a few spacers so you can slip the assembly over the boiler a bit like this

[derek blakeParticipant @derekblake72550]

Good luck with your build George, I look forward to your updates.

[Paul LousickParticipant @paullousick59116]

Bolting the hornplates to the boiler stays is common practice on model engines but it is not allowed in Australia for larger, steel boilers. Instead a separate mounting has to be added to the side of the boiler. Another requirement is that a 5mm tell tale hole has to be drilled axially in the end of the stays. These will leak if the stays within the water space of the boiler are coroded.

My 6" scale engine weighs 600kg and it is not good practice to place a shear load on the mounting bolts. Therfore the boiler on my engine rests on a ledge, welded to the bottom of the hornplates and the mounting bolts only take an axial load. I also do not like using threaded holes and all bolts have nuts which are easier to replace if a thread is damaged.

Paul.

 

Edited By Paul Lousick on 26/08/2019 23:46:40

[Nick Clarke 3Participant @nickclarke3]

Posted by Paul Lousick on 26/08/2019 23:45:29:

Bolting the hornplates to the boiler stays is common practice on model engines but it is not allowed in Australia for larger, steel boilers. Instead a separate mounting has to be added to the side of the boiler.

Edited By Paul Lousick on 26/08/2019 23:46:40

Please excuse my ignorance on things traction engine, but is this method I have seen used in model engines of bolts through hollow stays not used in the full size?, and by extension is an accurate model not permitted if it is to meet the Australian code?

While plate thicknesses and joining methods might well need to be adjusted to make a safe working model, if I have understood this correctly, does the visible structure have to be changed too?

Interested to know.

[George JervisParticipant @georgejervis86082]

Hi everyone

I had a set back I managed to break 2 drill bits while drilling the stays, I have found a firm that has spark erosion which has now been done. In the mean time I have cut out the horn plates ready.

George

[derek blakeParticipant @derekblake72550]

These things are sent to try us George, my boiler has been a nightmare from day one but I hope to get there in the end.

I would love a brand new boiler with everything perfect but at 2k its just not possible, my partner would kill me for starters, especially when she wants another trip to Euro Disney!

The forum has been a great help to me for my build, and can pick you up when you feel disheartened.

I look forward to seeing things progress, its good to see another traction engine thread going.

[George JervisParticipant @georgejervis86082]

Hi Derek,

This is a long term project and my first real build I'm going to take my time, I have a good group of very knowledgeable friends in my local engineering group, which are offering a lot of advise so between them and advise on here I'm sure I'll get there.

Theirs a few things which are confusing me when I start to make the wheels are the (spokes) riveted or screwed into place the same question for the wheel strakes if they are riveted too ? if so are these homemade or can you purchase them and what size?

George

[derek blakeParticipant @derekblake72550]

Hi George

That's one thing I wish I had to my aid, and that's a group I could join that I could speak too for advice.

I'm very much building alone, other than the forum guys I keep pestering for advice.

I have questions everyday, but feel I shouldn't keep asking and pestering so I try and google the answers,

I know Jason has built the Minnie so I'm sure he can advise, but from what I have seen bolts are used for initial setup and then you go around and replace with rivets but I maybe wrong.

[Dave HalfordParticipant @davehalford22513]

 

It's all in Mason's Minnie book. His process works well.

Blackgates sell strakes and spokes.

Edited By Dave Halford on 27/08/2019 10:57:44

[George JervisParticipant @georgejervis86082]

Hi Dave

I've found my book now SWMBO has had a tidy up

I have the strakes and spokes made I was just wondering about the rivets,

George

[Dave HalfordParticipant @davehalford22513]

Blackgates.

[JasonBModerator @jasonb]

Posted by Nick Clarke 3 on 27/08/2019 08:11:04:

Posted by Paul Lousick on 26/08/2019 23:45:29:

Bolting the hornplates to the boiler stays is common practice on model engines but it is not allowed in Australia for larger, steel boilers. Instead a separate mounting has to be added to the side of the boiler.

Edited By Paul Lousick on 26/08/2019 23:46:40

Please excuse my ignorance on things traction engine, but is this method I have seen used in model engines of bolts through hollow stays not used in the full size?, and by extension is an accurate model not permitted if it is to meet the Australian code?

Full size engines don't have hornplates they are a model thing. On a full size the sides of teh firebox continue up to provide the plates that the shaft bearings fix to.

I don't see why a model could not be made with full height sides to the firebox.

Not all models use the bolt through method, a couple of John Hainings designs particularly the ploughing engines used an angle welded to the curve of teh boiler much like Paul's sketch shows and the firbox sides were extended out the back to provide fixings for the hornplates.

Edited By JasonB on 27/08/2019 12:48:49

[derek blakeParticipant @derekblake72550]

I feel like my early attempt at a traction engine had copper sides from the to hold the gears and cranks etc.

I maybe wrong but I'm sure at the time it concerned my as it did others, but I guess it was just the design at the time.

I think it was a Bassett lowke

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