And Now for the Twin

A special section just for steam engines and boilers, as without these you may as well fit a sail.
Mike Rometer
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Re: And Now for the Twin

Post by Mike Rometer » Sat Sep 14, 2019 2:33 pm

RGSP wrote:
Sat Sep 14, 2019 2:16 pm
Now you've got all those stresses to either get rid of or live with.

I recommend marinading the welded unit in something which will produce a thin organic film on the steel, having dissolved a bit of grease beforehand.

Something around a 4% v/v solution of methanol in pure water would do. If need be though you can use ethanol, and the water can be a bit brown too.

In fact, it often works better for the machinist to just drink the marinading solution, leaving the welds alone. Nett stress is enormously reduced.
I do like the 'brown' drink, but the 'little yellow one' is a quicker stress reliever. :lol: :lol:

Work has continued this afternoon, with material being cut for valve chest covers. That has allowed me to think about con-rod to stroke ratios. A 6" rod gives 1.85:1, so I may push it out to 6.5" which would be 2:1. I don't want to make the finished unit too tall. Compromise, as with everything!
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Mike Rometer
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Re: And Now for the Twin

Post by Mike Rometer » Fri Sep 27, 2019 7:57 pm

Work has continued, not exactly 'apace', but forward movement is well evident. I'm not concerned about any leftover stresses that may reside within the base-plate it has machined well without further distortion, and there will be plenty of support from the pillars etc.

The valve covers have been cut and drilled, along with the steam chests, port cheat plates, and the block, which has also been tapped M6.

The big-ends are also well under way, with only a couple more tasks 'til completion.

Big-End Sheaves (6) (600 x 450).jpg
Big-End Sheaves (6) (600 x 450).jpg (85.46 KiB) Viewed 3624 times

Certain materials have become scarce so a shopping trip is needed to replenish supplies as soon as it can be arranged.
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A BODGE : - A Bit Of Damn Good Engineering.
TriangleTom
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Re: And Now for the Twin

Post by TriangleTom » Wed Oct 02, 2019 2:41 am

Love these posts! How are you planning on attaching the cylinder supports to the bedplate?
Mike Rometer
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Re: And Now for the Twin

Post by Mike Rometer » Wed Oct 02, 2019 8:07 am

TriangleTom wrote:
Wed Oct 02, 2019 2:41 am
Love these posts! How are you planning on attaching the cylinder supports to the bedplate?
Threaded and nutted underneath. The length has still to be decided once the con-rod length has been finalised. Plenty to be going on with in the mean time.
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Re: And Now for the Twin

Post by Mike Rometer » Tue Oct 22, 2019 2:42 pm

Work continues, but not necessarily in the obvious place. The purchase of some materials made the attention wander a little and having bought 303 for the studs I thought to cut some for the steam chests (20) and have threaded the 'block' ends, when perhaps I should have been getting on with the con-rods.

Steam Chest Studs (2) (600 x 450).jpg
Steam Chest Studs (2) (600 x 450).jpg (70.1 KiB) Viewed 3452 times

With the steam chest still in mind I added a little frippery to the covers, though it took a lot to actually push the button and start the cuts, what if it all went wrong?

Steam Chest Covers (600 x 450).jpg
Steam Chest Covers (600 x 450).jpg (73.93 KiB) Viewed 3452 times

Why 'G', well Cyril Taylor had a 'T', and Stuart Turner have a 'S' so Mike Rometer has a 'G'. :lol: :lol:
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A BODGE : - A Bit Of Damn Good Engineering.
Mike Rometer
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Re: And Now for the Twin

Post by Mike Rometer » Fri Apr 24, 2020 4:44 pm

As is the custom in these parts, especially when the sun shines, it is now beer o'clock. The w/shop has been abandoned for the day, and photos taken have been up loaded to the P.C. Beer pot to hand.

On looking back at this thread I seem to have neglected it a tad, so I will attempt to catch up.

The big ends housings were tidied up a bit (I think there's a bit to go yet, perhaps a few corners to go) and the rods taper turned, threaded and attached. Threading was done in the lathe and chased with a die I find that the quickest simple way to get a true thread, the die always seems to leave a better finish than the tool.
Con-rods (2) (600 x 450).jpg
Con-rods (2) (600 x 450).jpg (69.25 KiB) Viewed 2849 times
Whilst not a lot physical was going on I was allowing my two brain cells to rub together and eventually I've come up with my solution for the cross-head guides and mountings. Material choice is silver steel, however, whilst round would maybe do, I preferred square. A slot would be provided in the boss of the bottom cyl cover and a cross-bar fitted on the pillars to attach the bottom end. The cross-heads would be brass/bronze with a yolk small end on the con-rod with the gudgeon (wrist) pin fixed in the cross-head. (I hope that's all clear). Problem one. No square silver steel available in the required size (1/2"). I don't know about on the lee side of the pond but over here things like this are a problem generally, some materials are just not there! The only option was to make some round square!

Across corners of 1/2"square is a touch under 18mm which just happens to nicely sit in one of the 'T' slots on my mill. Clamped at both ends and a floating clamp in the middle 0.100" was removed. 0.100" is not quite enough, but there is a method in the madness (0.104+" would be more correct).
Crosshead Guides (3) (600 x 450).jpg
Crosshead Guides (3) (600 x 450).jpg (71.87 KiB) Viewed 2849 times
Bar turned over and repeat on the other side.
Crosshead Guides (6) (600 x 450).jpg
Crosshead Guides (6) (600 x 450).jpg (67.85 KiB) Viewed 2849 times
Last edited by Mike Rometer on Fri Apr 24, 2020 5:06 pm, edited 4 times in total.
Retirement is about doing what floats your boat!

A BODGE : - A Bit Of Damn Good Engineering.
Mike Rometer
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Re: And Now for the Twin

Post by Mike Rometer » Fri Apr 24, 2020 5:02 pm

Two parallels were loosely clamped to the mill table and side one of the bar clamped to each of them, everything tightened up and a half depth cut removed.
Crosshead Guides (7) (600 x 450).jpg
Crosshead Guides (7) (600 x 450).jpg (78.57 KiB) Viewed 2846 times
The rational is that this isn't quite as rigid or possibly accurate a set up, so leave plenty for removal later.

The bar then turned over and the last side cut to depth, then returned to the third side for finishing.
Crosshead Guides (9) (600 x 450).jpg
Crosshead Guides (9) (600 x 450).jpg (71 KiB) Viewed 2846 times
Boom boom!

Ahh! But what about the extra 0.008ish"? Well being a lucky fellow I have a small surface grinder so it will (perhaps tomorrow) be finished to exact size on there. I will cut it into two first as it is more than long enough to make both slides, and that will ease the grinding, as it is a 'hand pedalled' affair.

:D
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A BODGE : - A Bit Of Damn Good Engineering.
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fredrosse
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Re: And Now for the Twin

Post by fredrosse » Fri Apr 24, 2020 8:36 pm

I am so lucky to have found a big stash of "Oil Hardening" ground stock, ranging from 1/8 inch square to 1 inch x 2 inch, all 24 inch lengths, all individually packaged, with very mild rust. The surplus place where I shop is selling it at $0.50 per pound, and I have bought several hundred pieces, great hardenable stuff, costs 20X that amount at retail. Had to build a 40 cubby rack just to store the steel so I can approximately see hat I have. Got to get building new steam engines now.
Mike Rometer
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Re: And Now for the Twin

Post by Mike Rometer » Fri Apr 24, 2020 9:19 pm

GFS seems to be available here mostly in flats, not squares. I could get square up to 3/8" or 10mm but no bigger. As you suggest it is expensive, especially if you have to add P&P.
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A BODGE : - A Bit Of Damn Good Engineering.
Mike Rometer
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Re: And Now for the Twin

Post by Mike Rometer » Mon May 11, 2020 4:20 pm

Surface grinding has not been on the menu, due to too much 'stuff' in the way that needs to be moved before it can be used, and then put back afterwards. It includes cars and locos that can do without being splattered with grindings. I will get to it sometime.

Instead my thoughts have moved onto the small ends. Having a suitable lump I cut a section off and trued it, cut into two pieces and then cut the slot. One of those times when a horizontal mill with a side and face cutter would have been nice. I am however happy with the result so far, but there is still a ways to go. Little steps!
Small ends (2).JPG

Fred, I found some GFS in 12mm square eventually (too late). It was listed most peculiarly. All the thicknesses were listed together, but there was no logic to how each was listed, with different widths and lengths all mixed up, so I had to go through page after page to find it. My logic would say list small to large and short to long. A site search only turned up the thickness. :roll: :roll: :roll:
Retirement is about doing what floats your boat!

A BODGE : - A Bit Of Damn Good Engineering.
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