It's Stuart Hammer time......

[Sanjay F]

I bought a set of 'partially started' old Stuart Steam castings over a year ago; that phrase is always a bit tenuous and I really ought to have opened the box when I got it! 

You can see from the photos what I got; there are a couple of concern straight off the bat:

- The column has a hole in the front face which looks like a casting deformity - bit of JB Weld should sort that out
- The mouthpiece is a write off the mounting holes are randomly placed and an attempt at the tricky shaped hole has failed
- There is a second valve chest which leads me to believe the first may have failed, but yet to be determined

From what I have read the mouthpiece and gland are the bits which are the most 'interesting' and there are several approaches to be had. I'll get myself a new casting and then tackle that in time. I have builds in Model Engineer from 2017 and 2018 and also an older build from 2000 which includes the rather nice lubricator.

I have seen the superb completed one by Dave (chipswitheverything) which is clearly the standard by which all other version should and will be judged .......... 

EDIT: Maybe the casting hole in the column is okay as a slot has to be machined at that point for the mechanism?

[Jasonb]

As the top of the iron mouthpiece casting has no doubt been used to spot through the holes into the cylinder if you start correcting those you may well need to redo the holes in the cylinder by plugging or a new cylinder. An insert JBWelded into an enlarged hole would take care of the shaped piston hole

The bottom 4 holes that hold the gland don't really have to be in that position so you could move them all round by 45deg and just tap new holes into the iron casting. Or as they are under less load plug and redrill/tap

That leaves the gland which could be cut from a slice of bronze bar for half the cost.

Might just be some casting flash filling the slot in the column.

[Sanjay F]

The gland is cut from stock bronze/brass so I'll throw the existing piece in the bin and start that again

The mouthpiece is the 'usual' pretty penny from our friends at Stuarts so I'll try and correct the one I have; what's the worst that can happen, I'll mess it up further and have to get another one!

The mouthpiece came 'fitted/bolted' onto the cylinder so the holes on that side and are pretty good, it's just the gland end which needs attention, but I'm going to make that from stock and can rotate it as you have said 

The cylinder cover has been made but is not sitting flush so may just need a small undercut on the boss.

The anvil is a peculiar casting, it shows the outline of what the finished items should look like but has them cast together so the top part will need chopping off???

[Jasonb]

Cast as a dummy, would look nicer as a separate part dovetailed into place. You should have time to do it before Xmas nut cracking season starts.

You may just need a small chamfer to the cylinder bore so the cover sits flat.

[Sanjay F]

Cast as a dummy, would look nicer as a separate part dovetailed into place. You should have time to do it before Xmas nut cracking season starts.

You may just need a small chamfer to the cylinder bore so the cover sits flat.

100% - definitely better dovetailed; I have seen dovetail cutters before in fact used a miniature one when building the Hicks oscillator recently.

[Sanjay F]

I made a start on cleaning up the mouthpiece and have bored the hole to 0.600" ish and will now make a suitable plug and loctite it into position.

Question

The new centre hole needs to be concentric to the cylinder which shouldn't be a problem as I can dial in the boss on the cylinder side (red arrow). However just looking at the hole on the gland side it doesn't look concentric and it needs to be. Should I also plug gland side and drill/bore straight through from the cylinder side, then flip the piece over in the lathe and dial it in using the new centre hole, and rebore it to 7/8" (blue arrow) and thereby ensuring the alignment?

[Jasonb]

Hardly worth plugging the large hole. Set it up in the 4-jaw and clock the smaller hole true then bore out the 3/4" until it is true. Then just make the gland to fit the new larger hole of say 0.900"

[Sanjay F]

The hole is plugged and loctited and took me ages to dial in, but it's there ready for drilling.

Looking ahead at the various options for making the slot, I'm going for the insert method by John Bertinat outlined in the earlier editions of Model Engineer (see photo) - why, well it feels the most comfortable to me at my skill level and the equipment I have. In order to do this I have to start with a 1/2" hole to make the outer radii so I'll be drilling the new hole to that dimension and similarly on the new gland once I've made it

EDIT

The JB method calls for a brass/bronze bush to be inserted into the mouthpiece so looks like I'll be drilling out the plug I've just made and loctited! No great loss, it's dialled in and ready for action 

[Chipswitheverything]

Hi Sanjay, many thanks for your flattering comment on my 'hammer, I blush as I eat my Weetabix here ...   It has been suggested to me that no actual steam hammer ever looked like that, it should be covered in dirt and crud ....     Will be interested of course in how your build progresses.

As Jason has been advising, it looks as if the castings can be sorted out without further assisting the shareholders of Messrs Stuart.
 I made up, as you may have seen, a silver steel dovetail cutter at a more shallow angle than the 60 degree cutters used for machine slides. If you have a small 60 degree one then it may be OK, but if you need to buy one specially, then it might be worth just doing what I did, making a little cutter,  and getting the preferential angle for little or no cost.
The method used by JB for the gland is ingenious, I might have done it that way had I not had the various bits of apparatus that I used on the Myford to slot out the shape.    Personally, I think that Stuart Turner and / or Stuart should, decades ago,  have had a broaching tool made up and done those two awkward holes for the builder, who they knew very well would be faced with something rather tricky ....  Dave

[Jasonb]

I can't see any reason the piston rod needs to be shaped as it is. It would work just as well if it were a rectangular section of 1/2" x 7/16" with the corners rounded to say a 1mm radius.

That would make it very easy to mill out the two holes the rod passes through with a 2mm dia cutter.

[Sanjay F]

Hmmm......interesting, I would still need to make the bush which is no problem and that does seem far simpler!

How do I radius the corners of 1/2" x 7/16" rod at 1mm along its length?

[Jasonb]

Not too hard to do with a file using the rectangular hole as a gauge. Or you could invest in a rounding over cutter.

[Sanjay F]

Rounding cutter................yes, that's seems a good way to get accuracy along the length, they are too pricey either! 


EDIT: Aren't too pricey! 

[Sanjay F]

It's taken a little bit of work but the mouthpiece is now in much better shape with the assistance of a mandrel

It now has parallel sides, which are 90 degrees to the bore, the correct distance apart, the boss is the correct depth, the holes cylinder and flange side are now concentric. I had to take what should have been 0.875" diameter out to 0.935" to obtain concentricity on the flange side

Next up is to make up a bush for the cylinder end and the gland for the other end. I've ordered a rounding cutter and am quite excited by the prospect of trying Jason's new approach to the piston rod as it clearly something which continues to cause problems for builders.

[Sanjay F]

The cylinder bush has been made and test fitted; I'll leave it loose until I have milled the slot, next up the gland and I must fill in the randomly placed gland mounting holes