Author Topic: Stuart No 1  (Read 13948 times)

Offline Kim

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Re: Stuart No 1
« Reply #30 on: January 21, 2019, 05:12:25 PM »
Nice boring, Jo!
It's always nice when things workout as planned, isn't it? :)
Kim

Online Jo

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Re: Stuart No 1
« Reply #31 on: January 21, 2019, 08:00:17 PM »
Thanks Kim,

Eric is also doing a bit of boring but someone told him size matters and he must have thought they were talking about boring heads   :facepalm:

Jo
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Offline Chipswitheverything

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Re: Stuart No 1
« Reply #32 on: January 22, 2019, 02:06:44 PM »
Your engine is coming on very well Jo, and quite rapidly!   i liked the neat and simple surface plate arrangement for determining the marking out of the column foot from the crosshead guide.  The chunks of the No 1 are hefty enough to give the feel of doing a bit of "proper" engineering, I thought so anyway!   Dave

Online Jo

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Re: Stuart No 1
« Reply #33 on: January 22, 2019, 04:25:33 PM »
Thanks Dave  :)

I have done the major part of the crankshaft today. I have used silver steel for the two shafts and some specially aged FREE cutting mild steel for the two webs. Milled to size to remove the special coating and any surface dings, then the two shaft holes bored using a boring head.

I was going to turn the outside by super-gluing them to a short end but the workshop is getting a bit cold and it was not holding. For the same reason I am not going to attempt to Loctite the shaft together this evening  :hellno:


Eric has been telling me how wonderful his huge boring head is I have had all of the sales pitch.. two speed, fast retract... The problem as I see it is height  ::) He was promising more pics of his build at lunchtime :stickpoke:

Jo
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Online Jo

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Re: Stuart No 1
« Reply #34 on: January 23, 2019, 03:50:39 PM »
The outside edges of the crank webs has been turned and a bit of polishing done, so it is time to secure the crankshaft with Loctite at the correct location and leave it in a suitably warm place to go off.

Jo
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Online Jo

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Re: Stuart No 1
« Reply #35 on: January 23, 2019, 04:08:29 PM »
While still waiting from Eric's pics of his cylinder work I have moved on to looking at mine.

The cylinder has been faced on either end and one end has had the outside turned  :facepalm: This feature is of such a depth that it is not safe to hold on that end to bore the cylinder, which is ok as with the dimensions remaining I chose to face and bore from that end and hold on the other.

I had 2mm extra to come off on the faces, the cylinder had been faced such that there wasn't a lot left on one end so that had to be the end to face off ready to machine the bore square to it and of course there was hardened flashing all around the ports :paranoia:

First the end face was skimmed - this is now our reference face to which everything is going to be square and it will also be the bottom face of the cylinder on the final engine ;)

The stops were put in place so that the boring bar did not catch Mr Silky's chuck jaws and the cylinder bored out to 50.7mm, the final cut repeated without moving the cross-slide to make sure the boring bar had not deflected on the previous deeper cuts.

The bored cylinder is ready to have the bottom face machined which will remove the rough edge around the bore and I have found the two covers.

Jo


« Last Edit: January 23, 2019, 04:12:30 PM by Jo »
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Offline bouch

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Re: Stuart No 1
« Reply #36 on: January 23, 2019, 05:46:13 PM »
Hi Jo,

Looking at the photos in your latest post, I see something interesting about your cylinder casting, as compared to mine.

It looks like your cylinder has 3 sets of "lugs" where you could drill holes for drain cocks, each 90 degrees apart.  Since I built one, when I see a #1 at a model engineering show, I usually look at it and chat with the owner about it, and I can't remember ever seeing a set of #1 castings with this configuration.  My casting has only one place you could install drain cocks, exactly opposite the valve surface.  Not sure what this means, but I found it interesting...

How does your friend Eric's cylinder compare?

Mike

Online Jo

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Re: Stuart No 1
« Reply #37 on: January 23, 2019, 06:00:51 PM »
 :headscratch:  You are right. I wonder why they did that.

Eric's only has one pair.... He says it shows mine is a later casting.

Jo
« Last Edit: January 23, 2019, 06:03:59 PM by Jo »
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Offline Jasonb

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Re: Stuart No 1
« Reply #38 on: January 23, 2019, 06:28:19 PM »
Having them on one side allows you to run the pipework neatly down the frame if you go for plumbed in drains particularly if you use angled cocks.

It's coming along.

Offline bouch

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Re: Stuart No 1
« Reply #39 on: January 23, 2019, 06:48:44 PM »
Having them on one side allows you to run the pipework neatly down the frame if you go for plumbed in drains particularly if you use angled cocks.

It's coming along.

That makes sense.  I hadn't thought of that.

Online Jo

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Re: Stuart No 1
« Reply #40 on: January 23, 2019, 06:55:51 PM »
Some more pics from Eric  :)

He has mounted his cylinder up on a mandrel and has machined the two ends.

Not much progress as his Newal DRO display has packed up  :toilet_claw:

Jo
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Online Jo

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Re: Stuart No 1
« Reply #41 on: January 24, 2019, 01:46:33 PM »
Eric tells me that he has ordered a full new DRO set from Colin at CBR Electronics for less than he could pick up a second hand Newall DRO display so that should be with him by Saturday  :)

In the meantime I have been making some more swarf. I started off by looking into making a mandrel the same as Eric but then thought I would see how good Mr Silky could hold the cylinder on the bore... the finger dial showed it was within 0.02mm of true :cartwheel: which meant I could cheat and use tailstock support to do the cylinder machining.

Both outer edges have been taken down to the 76.2mm diameter of the covers minus twice the thickness of the cladding. The flange is a little wider at the bottom as the valve chest is out of line relative to the centre line of the cylinder and ports   :thinking:

Time to think about the covers - they are plenty big enough. Even the chucking spigot is very well cast but I still machined it parallel so that they could be held in a collet for machining the outside edges and the bottom face of the covers.

Jo
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Online Jo

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Re: Stuart No 1
« Reply #42 on: January 24, 2019, 05:08:14 PM »
The first cover has been turned to fit on the top of the cylinder.

Before doing the second I had to look at the piston rod: I mentioned earlier that the piston rod already had centres in it and had been very rough turned round. The drawings show two different diameters, I chose to target the larger diameter (allowing me to go for the smaller if it went wrong  ::) ). I am pleased to say it machined nicely at 8.73mm  :)

I now know what size to make the hole through the centre of the bottom cover so now I can start machining that. I am not going to finish turning the piston rod as I want to check the dimensions: The piston is 19.05mm thick and the piston rod on one drawing only shows 16mm of thread and no locknut, the other shows a longer piston rod and a lock nut.  :noidea:

Jo
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Offline jeff l

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Re: Stuart No 1
« Reply #43 on: January 24, 2019, 05:18:39 PM »
 Jo , Great job on the number 1 . Jeff

Offline Jasonb

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Re: Stuart No 1
« Reply #44 on: January 24, 2019, 06:28:03 PM »
The piston is 19.05mm thick and the piston rod on one drawing only shows 16mm of thread and no locknut, the other shows a longer piston rod and a lock nut.  :noidea:

Jo

I think the earlier engines with a one piece piston just screwed that onto the end of the rod where as the later two part pistons have the rod going right through to take a nut.

Solid option here http://www.steves-workshop.co.uk/steammodels/stuart1/introduction/stuart1large.jpg