Stuart 10H- How to machine trunk guide

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Stuart 10H- How to machine trunk guide

This topic has 16 replies, 8 voices, and was last updated 22 February 2015 at 17:04 by Dan Jones.

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28 January 2015 at 20:10 #3242
Dan Jones
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@danjones77555
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28 January 2015 at 20:10 #177618
Dan Jones
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@danjones77555
Hi guys,

I got myself a set of 10H castings as a little college project as I've finished all my work 5/6 months early. I've already done a 10V but the 10H is in my opinion a much nicer looking engine.

I've looked online and can't seem to find anything about machining the trunk guide for the cross head. I have a few possible ideas on how to do it but I hope someone on here who might have made one knows one of the best ways to do the job.

Thanks,

Dan.
28 January 2015 at 20:18 #177621
JasonB
Moderator
@jasonb
A lot will depend on what machines you have access to.

1. Clamp the casting to an angle plate on the lathe faceplate and bore the guide and face the cylinder mounting flange at the same setting.

2. Clamp casting to lathe cross slide packed upto height, use between ce3ntres boring bar for teh guide and flycut the cylinder mounting flange.

3. Clamp vertically to an angle plate on teh mill, boring head toi do teh guide and mill teh cylinder flange

I'm sure there are a few more ways, here is how Harold Hall did his

Edited By JasonB on 28/01/2015 20:20:50
28 January 2015 at 20:22 #177622
Dan Jones
Participant
@danjones77555
Jason,

Would I be able to ream the guide or is it best to bore?

Dan.
28 January 2015 at 20:23 #177623
steve de24
Participant
@stevede2433577
Dan, take a look at :-

**LINK**

I hope it helps, regards, Steve
28 January 2015 at 21:32 #177629
nigel jones 5
Participant
@nigeljones5
Im sure the guide is invaluable to some, but do they show the big end being bored and then slit? Not sure that's a good idea!
29 January 2015 at 07:23 #177640
JasonB
Moderator
@jasonb
No Fizzy its drilled for the bolts so they are in line then slit in half and then bored with the bolts holding it together.
29 January 2015 at 07:27 #177642
JasonB
Moderator
@jasonb
Dan, you will need to bore the hole anyway as its a cored hole in the casting so a drill won't run true and the reamer will just follow where the drill went. The two slots at the side could also affect how well a reamer would cut.

So not really much point in boring undersize and then reaming you may as well bore it to finished size and the crosshead can be machined to fit if you end up a bit over or under size.

Edited By JasonB on 29/01/2015 07:46:48
29 January 2015 at 10:21 #177663
Lambton
Participant
@lambton
Dan,

Jason has provided a selection of methods that represent good engineering practice.

A small but important point. When setting up ensure the outside diameter of the trunk guide runs as true as possible as the cored hole may not be concentric with the OD. The finished job will look much better with the bored hole finishes concentric with the OD.
29 January 2015 at 13:23 #177683
nigel jones 5
Participant
@nigeljones5
Take a look at photos 51-53…definitely slit after boring? (eccentric rod, not con rod)
29 January 2015 at 14:43 #177691
Neil Wyatt
Moderator
@neilwyatt
Fizzy, on the Stuarts the eccentric straps are usually only slit on one side, so you 'can nip them up to allow for wear' – though I doubt any 10V or 10H has ever run long enough to wear out the eccentric strap!

Neil
29 January 2015 at 15:54 #177702
nigel jones 5
Participant
@nigeljones5
Oh well, you learn summat most days!
30 January 2015 at 11:55 #177805
Ian S C
Participant
@iansc
Another way of doing big ends with a bush in it, before slitting, bore the big end, drill and tap the cap bolt holes, press in the bush material, slit the big end and bolt up, rebore the bush to the right size, the out side diameter of the bush will be slightly oval, preventing it from rotating. This is the method I use on my hot air engines, the con rods are usually aluminium, I'v used both bronze, and cast iron for the bush. This doesn't show the bush, must get a pic that does

Ian S C
30 January 2015 at 22:38 #177904
Paul Lousick
Participant
@paullousick59116
Hi Dan,

Not a 10H engine but this is how I machined the trunk guide for my Ruston traction engine.

1. Made a mandrel to turn the ends of the trunk guide between centres.

2. Turned a mounting plate on the lathe to accept the trunk guide. The mounting plate was made from an old pipe flange which I found in the junk bin and because it was turned and faced on the lathe prior to mounting the trunk guide, I knew it was accurately on centre. Clamps for holding the trunk guide were made from steel angle.

3. Supported the end of the trunk guide with a lathe steady and bored the guide.

4. I had to make a special boring bar holder to face the inside of the trunk guide for the stuffing gland. Made from a piece of round bar to fit the tool post, tapered at the front for clearance inside of the trunk guide and drilled at the end to fit a small (round) cutter that I use in my mill goring head.

Paul.
9 February 2015 at 11:01 #179062
Dan Jones
Participant
@danjones77555
Hi guys,

What's the best way of holding the box bed in the vice on the mill. The mill in question is an XYZ 1500 with an XYZ parallel flat jaw vice. Is it best to hold the box bed along its length; along the width where the two feet are; or strap it to the bed of the mill? The long sides of the box bed are tapered up so would the vice push it out of the jaws when clamped?

Thanks,

Dan.
9 February 2015 at 11:32 #179068
JasonB
Moderator
@jasonb
I would mount it to the mill bed feet upwards, put a sheet of paper between bed and casting so the rough surface is not straight on the bed. Use hold down studs and clamps wedged into teh inverted taper to hold it in place and skim teh bottom.

Then turn it right way up with clamps on teh feet to skim the top and drill the 4 holes.

A bit like this, I'm using plastic packets and a feeler gauge to get things level.

Then this
22 February 2015 at 17:04 #180800
Dan Jones
Participant
@danjones77555
Just a quick update on the 10H.

The box bed has had the top and bottom surfaces machined, all that needs to be done now is to drill the holes in the feet.

My plan of action was to then machine the soleplate but the casting was unfit for use, so whilst I waited for the new one to be delivered (Free of charge from Stuart Models- no fuss, just a quick picture as proof!), I started to machine the cylinder which would be next on the to-do list.

So far, the cylinder has been faced to length, bored to size and had the valve face machined. The next job is to machine the steam recesses and the passage ways. The way I think I'm going to do this is fix the cylinder to and adjustable angle plate on the milling table, set it to 90 degrees, and mill the recess. Then adjust the angle plate 25 degrees from 90 and drill through the passage. Is this a good way of doing the job or is there a more common practice?

Thanks,

Dan.
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