Author Topic: Little and large - building 2 vertical steam engines.  (Read 11461 times)

Offline Gas_mantle

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Re: Little and large - building 2 vertical steam engines.
« Reply #15 on: April 22, 2018, 06:05:07 PM »
Cheers guys.

Carl, I used the swivel base to position the vice so it is no longer parallel with the table then made fine cuts across the end of the work piece. The vice wasn't moved once I had positioned it 1 or 2o off parallel.

It seemed to work ok but I think I should have cut a slightly more angled taper.

Offline Gas_mantle

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Re: Little and large - building 2 vertical steam engines.
« Reply #16 on: April 24, 2018, 03:19:18 PM »
I had intended making the crank bearing next but haven't yet decided the best way so I opted for doing the crankshaft first. I decided for a small engine a fabricated one will be fine but may turn one from solid for the no4 engine.

2 steel blocks drilled to take the shafts will form the webs



A 7mm rod will form the crank pin



I did try the rotary table to cut rounded end for the webs but it was far from ideal



So it was over to the lathe, this looks a bit primitive but worked well for a few small cuts



They turned out ok  :)



So bit of 638 (or the green stuff as Zee calls it) and they were left overnight. I may pin the webs later but it's probably not needed on a tiddler engine like this.



Milling out the waste



That takes me to this





Peter.







Online Jasonb

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Re: Little and large - building 2 vertical steam engines.
« Reply #17 on: April 24, 2018, 04:11:59 PM »
For your bearings I would mill the two blocks to overall size. Then mount in the vice and indicate from top and one side to find the middle and then drill and ream the hole. Now rest on packing and set up in the vice holding by the two faces and indicate off the fixed jaw to find middle of the bearing and mill a slot, rotate to do all 4 sides keeping the same face against the fixed jaw. Finally mount on arbor to turn the faces round with a round nosed tool. There are a couple of pics of how I did the 24 vertical in that set.

Offline Gas_mantle

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Re: Little and large - building 2 vertical steam engines.
« Reply #18 on: April 24, 2018, 04:21:06 PM »
Cheers Jason, the bit I'm undecided on with the bearings is how to hold the small blocks in the lathe accurately enough so that I can turn the small raised rings at either end concentric to the bore, then turn them round and repeat etc.

I was going to turn each end in the 4 jaw and spent time setting up 4 times but it kinds seems to me there must be an easier way ;-)

Can you post an image of the bearing or plan ?

Thanks :-)

Edit - sorry, I see what you mean about an arbor now.

Online Jasonb

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Re: Little and large - building 2 vertical steam engines.
« Reply #19 on: April 24, 2018, 04:42:04 PM »
have a look at the big end bearings being done.


Offline Gas_mantle

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Re: Little and large - building 2 vertical steam engines.
« Reply #20 on: April 24, 2018, 04:49:49 PM »
Thanks, it's kinda obvious now you have mentioned it  :)

I'll cut the squares later and turn them tomorrow.

I have a collet system and some collet blocks on my shopping list for Doncaster in a couple of weeks to help with this sort of thing. (I think a faceplate could be useful for the no4 trunk guide too)

Offline Gas_mantle

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Re: Little and large - building 2 vertical steam engines.
« Reply #21 on: April 26, 2018, 05:58:26 PM »
Today I decided to tackle the main bearing blocks, they are made from pieces of 24 carat gold machined to 12mm square and 15 mm long, a central hole is then drilled for the 7mm shaft.



A thinner waist is then cut, this will fit in the upright pillars of the soleplate. I don't have an end mill the width of the cut I need but by cutting it in this orientation the stop buttons on the front of my mill table can be set to limit the x axis travel to ensure repeatability.

All 4 faces are cut with the part firmly against the vice stop.



So far, so good...



To cut rounded rings at each end I made a temporary tool from a broken parting blade, a test cut on a piece of scrap is made to test the profile.



The blocks are then turned on a close fitting mandrel.



That takes me to this stage





Overall I'm happy with how they turned out, the shaft lies squarely and rotates freely without any play  :)





Brass plates will next be machined to hold the bearings in position

Peter.







Offline crueby

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Re: Little and large - building 2 vertical steam engines.
« Reply #22 on: April 26, 2018, 06:05:24 PM »
 :popcorn:

Offline zeeprogrammer

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Re: Little and large - building 2 vertical steam engines.
« Reply #23 on: April 26, 2018, 07:47:01 PM »
They look great.
Neat trick using the parting tool.

But I can't quite figure out how you did it. Did cut at an angle through the steel cylinder?
Carl (aka Zee) Will sometimes respond to 'hey' but never 'hey you'.
"To work. To work."
Zee-Another Thread Trasher.

Offline Gas_mantle

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Re: Little and large - building 2 vertical steam engines.
« Reply #24 on: April 26, 2018, 07:56:56 PM »
The steel cylinder is just a piece of scrap used as a thick spacer / washer, all I did was to angle the tool post like it is for the scrap brass in the previous photo then gently plunge in using the handwheels to measure the cut and get them both the same

Online Jasonb

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Re: Little and large - building 2 vertical steam engines.
« Reply #25 on: April 28, 2018, 01:39:56 PM »
Rather than clutter up Graham's thread I just had a look at the costings for a No4 cylinder etc

Stuarts want 82.44 for the cylinder, valve chest and valve chest cover castings.

You could cut all three from a 3" long piece of 70x70mm square cast iron which would set you back 25.20 using M-machine prices.

Not sure where you worked out that it would be cheaper to buy the castings :headscratch:

Offline Gas_mantle

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Re: Little and large - building 2 vertical steam engines.
« Reply #26 on: April 28, 2018, 01:47:27 PM »
I bought the castings from another forum member at a reduced price so I didn't pay 82, once I factored in the postage on the barstock there wasn't a great lot of difference.

I'd like to have made from stock but when I can have a casting set for a similar price it seemed to make sense.

Online Jasonb

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Re: Little and large - building 2 vertical steam engines.
« Reply #27 on: April 28, 2018, 01:50:41 PM »
I was forgetting you used an alternative supplier.

May explain why Jo thinks casting sets are good value for money :LittleDevil:

Offline Gas_mantle

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Re: Little and large - building 2 vertical steam engines.
« Reply #28 on: April 28, 2018, 02:04:25 PM »
To someone like me who has limited experience a casting of that size will probably look better than a barstock one, I already have the trunk guide so in the interest of making the whole engine look attractive I bit the bullet and bought the castings since the price was similar.

The rest of the engine I think I can make from stock and it should look ok, it goes against the grain a bit with me in buying castings but in this case it just made sense  :)

The 80 I mentioned to make the engine in another thread was for everything needed to make the complete engine :-)

I want the no4 to be a fairly powerful engine - any thoughts on pistons / rings ?  The graphite yarn I use on small engines doesn't sound ideal so I have considered trying to make from cast iron.

Online Jasonb

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Re: Little and large - building 2 vertical steam engines.
« Reply #29 on: April 28, 2018, 02:11:17 PM »
You hardly see any of the cylinder once the cleading is in place  ;)

Why not have a go at making a couple of CI rings, piston could be either iron or aluminium