Twin Cylinder Steam Engine

[Darren]

A little shop time this evening, not much so progress a little slow tonight.

Having now re-set my mill it was time to get back to making the little brass pillow blocks.

The source of material was to be cut from this 1 3/4 x 1/2" bar







All the sides done now for the ends





All done, I left them 0.1mm oversize to allow further machining and for possible vice/lathe jaw marks to be removed in the final clean up/polishing stage.



Next job was to drill the crankshaft holes. Notice I have made and adjustment to my vice stop. I found that positioning such small pieces at one end of the vice was not the best way to go about things. Mainly because there is no bottom support in this area and when clamping and pushing down on the part things could go horribly wrong.
So I added a 6mm brass screw (with the end polished) and locking knurled thumb nut. This really improved the situation.

Also notice I have marked the datum surfaces.  The bottom and one side. This is because the crank hole is not central and we need to be aware of this in further operations for correct orientation.



Holes were center drilled and then drilled to 4.5mm.



And this is where I finished off for tonight. A little further on....

[Darren]

I forgot to say, when suitable I like to add a little

"what have I learnt from this episode".....

Cutting four little blocks and then trying to machine them all to the same size was a little difficult. Not impossible as you can see. But I believe this type of task would be easier if one long strip was machined up first and then cut into the four lengths required. Followed by machining to length.

It seems that when four individual blocks are put in the vice at the same time they move by different amounts when the vice is tightened. So they do not end up the same size after machining.

It's slight, but it did exist. I got there in the end with a little dose of patience.

 

[Darren]

John, Can I ask you for a little bit of advice please..

I need to make an order for some small screws, typically in the tiny range of 2.5mm. I can look through your logs and estimate what's required but for small engineering I'd also like to order for the future at the same time.

Could you give a general list of what you find handy to keep on the shelf? Only the small stuff, say up to 4mm.

I understand you order from here http://microscrews.easywebstore.co.uk/default.aspx

[Darren]

And so we proceed with the pillow blocks a little more this evening ....


Oil hole marked up, center drilled, drilled out to 2.5mm and finally tapped 3mm.
I had to hold two together because my make shift parallel "a large HSS lathe tool" was too wide for just the one block.



All four done. Here I'm lapping them all true to size on all sides to each other. I have mounted all four onto a 4.9mm drill bit to line up the crankshaft bores. (at this stage they are drilled to 4.9mm as I will ream them to size later) By lapping not only will they all be the same size externally they will also have their bores in a perfect line when mounted.
Note the use of the now famous lathe bit clamped to the bench. This is to ensure that none of the pieces tries to turn. Give em half the chance and they will...!! It also ensures a square angle is kept between sides.



All done



I'd previously pop marked the bases to help with orientation during each machining process. Just checking they are still there.



Drilling the base mounting holes



All done, I don't currently have a 2.5mm tap, one is on its way so tapping can wait till later.



Now onto some profiling purely for aesthetics. I'm using a semi ball nosed carbide cutter. Tough stuff this brass ya know...!!
OK, it was the only cutter I have with any sort of small radius.....



And the other side



Off to the mini lathe to form the boss's, I chose 1mm for looks.



All done on both sides,
My missus called them "little cameras"
All they need now is the bases tapped and a general de-bur followed by a final clean up.

[sbwhart]

Looking good Darren 

Stew

[bogstandard]

Darren,

Because of being tight, I make the most  out of what I buy. So if I need 2mm screws, and 2mm studs, I will buy long screws, and cut them down to make both items. It can't always be done, but a lot of times, you will find that short screws are the most expensive. Without actually looking at the plans, I think most screw lengths are about 6mm. It does pay to buy in the bulk sizes, say 50 or 100 instead of 10's. They are a thing I have in stock all the time, so really, I can't give you a blow by blow for this engine.

What I tell people who are building this engine is to make the holding bolt holes a little larger, so instead of 2.5mm, make it 2.6mm. Doing it that way gives a bit of 'fiddle' factor to get it running a lot smoother. In fact, when you do the crosshead bars, you will definitely need to fiddle with those to get the crossheads to run up and down smoothly.

John

[Darren]

Hi John, sorry I wasn't asking about this engine specifically as I can get most of the info I need from your pages.
I was thinking in more general terms for typical model engineering as a whole, inc engines.

I should have been a bit clearer.

I'm thinking m2.5, m3, m4 would cover most things in a couple of lengths. Would that be correct, it seems from your reply it is.

(5,6,8 I tend to have a good stock of anyway as it suits my music side. Along with a few bsfs and ba's.)


The reason I ask is because not the sort to go ordering 5's and 10's. I tend to order by the standard box be it 100/200 or so and be done with it for a while, if not for ever 

It was just a general question 

[bogstandard]

Darren,

Thanks for the explanation.

For SS screws, I would stick with 2mm, 2.5mm & 3mm. Like I said, check the prices between the longest and shortest. It takes no time to cut a long one down, but if you only have a short one, it is difficult to make a long one. Don't forget to get washers and nuts, you don't use a lot, but I would get 100 of each size, just for stock.

For 4mm and up, I would just go for standard off the shelf stuff.

Just a little pointer on how I make my engines. During making, everything is held together with any old screw that will fit. Only on final build do I use the SS cap screws. Because they are so soft, it is easy to strip out the heads with continually tightening and untightening, especially on the smaller sizes, and they are too expensive to be thrown away.

John

[Darren]

Thanks John that clarifies things, I'll start making an order up 

Re soft, I'd never considered SS bolts to be soft before. I recently bought some 3mm countersunk for the insert toolholders I made recently and noticed that the heads don't seem to last more than a couple of tightens. I assumed these were cheap bolts and not very well made, but reading your reply above is interesting.


I think the reason I asked in the first place was because I was surprised to see metric threads on models. I always thought the God's insisted that BA or ME etc was compulsory or you'd be poked with a hot stick and banished from society.....or at least ridiculed by your peers.

Thankfully that's not the case 

BTW, Googling to see if ME actually existed and wasn't a figment of my imagination I found this page....could be handy for some of us. You might want to turn your sound off first though 
http://www.aonx97.dsl.pipex.com/WS-page/table-page/tables.htm#ME

[sbwhart]

Hi Darren

This is where I get my ME taps and Die's from http://www.tracytools.com/tapsanddiesmodeleng.htm ther's still quite few places you can get them, for my loco build ME and BA is used excusivly but I've found that some of the smaller sizes they call up such as 8BA allan grub screws are as rare as rocking horse droppings, so in places I,ve had to revert to metric.

Ther's nowt wrong in changing thread type after all your building the model for your pleasure no one elses, you just have to be carfull that your not compromising something else with the change ie thread getting too close to the edge etc etc.

Just have fun and use what you have at hand

Stew

[bogstandard]

Darren,

Yes SS is a lot softer than high tensile, and I only use SS normally for either bling factor or in an oily wet evironment. They are not really strong enough for general purpose work unless you can get hold of the very expensive ones (our normal ones are A2 grade).

BA is trying to die out slowly, but model engineers won't let it. It is preferred because of the complete range of sizes you can get in it. I think the range goes from 0 to 24 BA, but only up to 18 BA is generally available. So really it is an ideal range for true scale model engineers.

ME threads are the standard for our steam connections and other fine thread applications in larger sizes, so where BA finishes, ME carries on with a full range of 32 and 40 TPI threads (up to a standard of 1/2" diameter), but I have noticed some even larger sizes are becoming available.

That is a very good link Darren, you should pop that under the resources heading to stop it getting lost.

John

[Darren]

No, no, no........Stew I don't want any ME taps and dies  

I have a hard enough time trying to figure out what a 126/347th is I don't want another system  

Metric will do me fine, it's so simple....

[sbwhart]

Metric will do me fine, it's so simple....

Thats what I like to here:-    keep it simple  : Metrics a great system 

Stew

[Stilldrillin]

Metric will do me fine, it's so simple....

Thats what I like to here:-    keep it simple  : Metrics a great system 

Stew

Yep! Fully agree...... 

So, why am I awaiting delivery of 1/8" Whit taps & die? 

David D

[Darren]

Wouldn't M3 have done David 

I break taps to often to be buying overpriced ones 

But I can see for pipe fittings I might be "forced" to use ME, but it will be sparingly as poss....

[Stilldrillin]

Wouldn't M3 have done David 

I break taps to often to be buying overpriced ones 

But I can see for pipe fittings I might be "forced" to use ME, but it will be sparingly as poss....

I`m threading 1/8" rod....... 

David.

[sbwhart]

I break taps to often to be buying overpriced ones 

I very rarely break a tap :- touch wood etc etc, but I think thats down to a baptism of fire I experienced when I was an apprentice. Each group of first year apprentices had a project to complete once they finished there tool kit, for our year it was a model mill engine I had the job of making the governer, when i came to tap the frame to take the governer I broke the tap and there was no way we could get the broken tap out, I took a lot of stick from the supervisors and the other apprentices. The model is still on display in the board room along with all the other projects, I alway sneek a look to see if the tap faries have got that tap out, I still feal embarised about it:- I think thats why I'm so carfull when tapping. Sorry about going so off topic  

Stew

[Darren]

Brum Brum, Bruuummmmm........



Getting excited now, I can see and hear it, cept it doesn't really go Brum Brum does it 

[bogstandard]

For steam engines Darren, it is Chuff Chuff Toot, with the 'oo' extended to give 'toooooooooot'

Coming along well now.


Bogs

[Darren]

Thanks John that's them words I was looking for.....

TBH I'm really enjoying building this so far. It has forced me to re-evaluate the way I do things. I've had to set up the mill properly, "use" the mill dial indicators, and generally think about accuracy and tolerances.

Exactly why I chose to build one in the first place. 

After fitting the vertical DRO and stopped playing with less than half built engines I managed to get a little marking out done along with some plate cutting.

3mm aluminium from and old lab instrument casing. Yet another presy from a kind gentleman up north.



Machining the widths equal







Well that’s about it tonight, surprising how long the marking out takes.
I wonder what all the lines are for 

Rhetorical......

[Divided he ad]

Brum Brum, Bruuummmmm........

         


I like that a lot


Looking very good Darren....I'm looking forward to the day it goes Chuff!    Definitely not as much as you though! 


Marking out.... I've lost whole evenings before now!!   




Ralph.

[Bernd]

Lookin' real good there Darren.

Bernd

[sbwhart]

Nice one Darren 

Time spent marking out carfully is time well spent:- stops you straying onto the path to the dark side young Skywalker  :- measure twice cut once.

Stew

[Stilldrillin]

Steadily taking shape nicely....... 

David D

[Darren]

I'm looking forward to the day it goes Chuff!    Definitely not as much as you though! 

You wanna see me go "Chuff"   

I'm not sure if that's very nice or not...........