Phil Mortimers 7mm WorkBench - Mercian Vivian Style Garratt

[PhilMortimer]

No further work has been done on the crossheads and none likely for the next few days, as work has become pressing at the moment.

Edited January 21, 2017 by PhilMortimer

[PhilMortimer]

The crossheads have been finished and the N/S piston rods affixed. The crossheads were drilled out to final size (a push fit) in order that they accept some 1.5mm dia N/S rod. This rod was partly annealed in the region that is inserted into the crossheads, prior to soldering in place. The N/S rod was then flame soldered into the drilled crossheads. Some slight adjustment to the alignment of some of the rods was nessecary, to ensure that they were square to the crossheads in all axes. Use of the bending bars and some brute force made this easier. Crude, but effective,

 

Here are the crossheads in their intial and partly modified state.

 

WF_Garratt_119 by Phil Mortimer, on Flickr

 

And here are the final items with the cast brass piston rods replaced with drawn N/S rod.

 

. by Phil Mortimer, on Flickr

 

There is still some cleaning up to do and final tweaks to the rod alignments, but I think this is a distinct improvement, don't you?

 

The next stage is to make up replacement slide-bars, which will start shortly. After that, each piston rod / crosshead assembly will be paired with a specific cylinder end in order to assemble the slidebars to the cylinder ends and get a good sliding fit. More on this later.

Edited July 2, 2017 by PhilMortimer

[PhilMortimer]

I was tired after work last night. I got as far as rough cutting some N/S strip form the new slidebars before deciding to quit. Some days you just have to leave the bench alone and soldering under those circumstances wasn't a good idea. Hopefully more progress in the next few days.

[PhilMortimer]

I've not been feeling great the past few weeks and the garratts are driving me crazy, so I've put them aside for a few days to contemplate how to proceed. I have something else to work on at the moment to keep me occupied (2 x South African Class 91's in 4mm scale, 9mm gauge - which are also exercising the brain!).

[Simond]

Well, Phil,

 

You suggested that it was "my fault" that you are now considering a milling machine....

 

Well, in return, its "your fault" that I have now purchased a Garratt kit... (though I guess you could share it with Giles....)

 

Hope the mojo returns in full force in short order

 

Best

Simon

[PhilMortimer]

Thanks Simon,

 

Although I like to finish one project at a time, sometimes one needs a little break and some variety, rather than just constantly battering away at the problem . The class 91's have been stalled for a while for the same reason, but now I have worked out the way forward with them. Sometimes putting things to one side for a while helps the brain cogitate.

 

Good luck with your garratt - I'm sure you'll make a great job of it. post pictures!

 

But I still don't have a mill yet!

Edited February 2, 2017 by PhilMortimer

[Giles]

I'm sorry you're suffering with these - I'm not surprised- I found one extremely heavy going, and two must be torture!

However, the eventual result will be something quite special. There are a few around, but very few 're-worked' ones, I suspect... and they do look nice!

[Giles]

This was the Garratt that I gave a home yo

 

[PhilMortimer]

Thanks Giles.

 

Ooo. That does look nice! Nicely worn and weathered.

 

I think much of my gloom is just I'm feeling under the weather at the moment and it's nuts at work. Some warm weather and I'll be back at it. I know enough that if I try anything in this mood, I'll just have to redo everything!

 

Still, that nice looking dirty garratt is something to aim for!

[PhilMortimer]

In case anyone has been wondering what I've been up to whilst on my garratt break,

 

http://www.rmweb.co.uk/community/index.php?/topic/120295-phil-mortimers-workbench-4mm-scale-and-7-mm-scale/?p=2630352

 

I'm looking forward to getting these complted and then returning to the garratts!

[PhilMortimer]

OK, This hasn't been totally forgotten. To be honest though, I needed a break from it. However, I've still been pondering assembling the valve gear and crossheads whilst working on my pair of OO9 diesels. Now that the body shells of these are coming to completion, I'm starting to turn my mind back to this and developing a strategy of progressing this build.

[Simond]

Hi Phil

 

Mine's on the back burner at the moment, whilst waiting for the milled frames. Currently expected end May or so, along with the motors.

 

I took a diversion into a Dukedog to keep myself entertained, but I'm expecting a delivery of ballast tomorrow, so it might be back to the layout for a wee while!

 

And in my lunchtimes, when not doing side play diagrams for S7 modellers on Western Thunder, I'm drawing up a small sailing coaster from photos, which will be laser cut from card, will add a bit of scenic detail when the harbour gets built. And if that works ok, I'll go get some photos of sailing barges from North Kent, tomorrow, mañana!

 

Best

Simon

[PhilMortimer]

Do we get to see photo's of said sailing barges?

 

P

[Simond]

Phil

 

Don't hold your breath....

 

Best

Simon

[PhilMortimer]

With the impending completion of the bodywork for the narrow gauge Class 91's, it is time to resurrect this project.

 

in our last exciting (!?) installment, we were left with the cliff-hanger of new piston rods having been fitted to the crossheads and the dillema of how to fit the slidebars. Well the dillema still exists, though I have some ideas which will require some experimentation and the use of the cross heads. However, to get me gently back into this, I will finish the cross heads, which requires making up and fitting the connecting rods. Each connecting rod is made from a three piece lamination, as as I have two loco's under construction, each of which has 4 connecting rods, I have to manufacture 8 rods in total. The picture below shows the 8x valve gear frets laid out on my work bench last night to encourage me.....

 

. by Phil Mortimer, on Flickr

 

Since it is supposed to be wet all weekend, I hope to make some progress on this over the next few days.

Edited July 2, 2017 by PhilMortimer

[PhilMortimer]

OK, it wasn't as wet as expected over the weekend, so I didn't make as much progress as I'd like. Garden and Canyon duties got in the way. Still, I did get all the connecting rods cut out, cleaned up and the fret attachment tabs filed off. Each rod consists of three laminated etches and they have been grouped together, ready for soldering tonight.

[PhilMortimer]

The connecting rods were soldered up last night and the first pass at cleaning them up and blending in the laminations was performed. Each rod consists of three etched laminations, all held together and soldered. To ensure good alignment, drills are passed through the holes in the laminations and everything held together with crocodile clips. I made a simple jig consisting of a block of wood into which the drills were drilled using my drill press to ensure they were at 90 degrees to the wood and parallel to each other. The positioning was dictated by the holes in the rods. The etches were then treaded onto the drill bits, clipped together with crock clips and soldered by running solder along the edges using my very hot 60W soldering iron. With a little flux, this pulls the solder in quickly and results in a nice solid rod with not too much cleaning up (the etches were quite flimsy on their own). The picture below shows the final rod to be soldered on the jig, with a pile of rough soldered completed ones lying in front.

 

. by Phil Mortimer, on Flickr

 

After removing from the jig, a first pass of cleaning up and polishing the rods was undertaken, to smooth the edges and re-inforce the illusion that the rod is a single piece of metal. Here are the rods after the first round of polishing, along with the piston rods and cross heads.

 

. by Phil Mortimer, on Flickr

 

Finally, here are a couple of (not very good) shots of the assembly line

 

. by Phil Mortimer, on Flickr

 

. by Phil Mortimer, on Flickr

 

More tonight I hope, probabaly drilling and tapping the crossheads for the small end attachment.

Edited July 2, 2017 by PhilMortimer

[PhilMortimer]

I have now started to assemble the slidebars. The first two units are shown below. These were the test assemblies to see if the plan worked. It did and I'm thrilled with how they've worked out!

 

. by Phil Mortimer, on Flickr

 

I had been putting off assembling these for a while, as I expected difficulties. In actuality, it was more fiddly than difficult and a whole lot easier than anticipated.

 

The slidebars are made from Nickel-Silver strip, rather than using the hard brass castings supplied. This was for two reasons. 1) N/S looks more like steel when polished. 2) The N/S strip was smooth and had constant dimensions, unlike the brass castings where would require a LOT of work to get them suitable for use. The castings were a few thou off 2x1mm, so that was the dimensions the new slidebars were made up to. I didn't have any 2x1 N/S in stock and it would take time to get hold of some (plus expensive shipping over the Atlantic), but I did have some 0.5x 2, so laminated two strips together to make up each slidebar. 227 degree solder was used, as the completed slidebars will have to undergo additional soldering operations. The 1 x 2mm slidebars are a near perfect sliding fit for the crossheads. Athough more work than using 1x2mm strip, the resulting slidebars are strong and perfectly straight.

 

After laminating each slidebar, they were cleaned up and polished to remove excess solder. They were then positioned on the cylinder end / gland using the piston rod and crosshead for alignment. Once clamped into position, the ends of the slidebars were then soldered to the cylinder ends, again using 227 degree solder. The crosshead is a tight fit in the cylinder end / slidebar assembly at this point, so was removed and both the slidebars and crossheads fettled until a good sliding fit was achieved. Each unit is adjusted until it passes a drop test (i.e. when held vertically, the piston and crosshead slide the extent of the slidebars without hesitation or significant slop. Probably a few thou needed to be removed from each cross head surface to achieve a good sliding fit.

 

Because each [iston / crosshead / slidebar assembly is fettled to fit, they ahve to remain paired. I do this by temporarily trapping the crosshead in the slidebar assembly, using maskol on the end of the piston rod. Maskol is easily removed when needed and can be seen as the dirty puple stain on the end of the piston rods in the above picture. It should be noted that both the slidebars and piston rods have been made overly long and will be trimmed down to a good fit when fitted to the loco.

 

All of this seems a lot of work, but it is worth spending time getting this right, in order to have a freely moving mechanism. Otherwise, it will come back to bite you in teh future.

 

So having proved the concept works (and works well), I now need to make up the other 6 slidebar assemblies. To do this, I have now rough cut 24 lengths of the 0.5 x 1mm N/S strip in preperation for soldering up the remaining 12 slidebars. This will occur over the next few days. The picture below shows 3 bundles of 8 rough cut N/S strip in preperation for soldering up. Also shown are the rough cast hard brass slidebars supplied with the kit that have been replaced with the N/S fabricated ones.

 

. by Phil Mortimer, on Flickr

 

The finished slidebars need a little more polishing, but have been stored carefully until ready for fitting. At this stage, the slidebars and piston rod will be cut down to teh final correct length. I need to do a trial fit to see if I can get the wheels off with the slidebars and crosshead fiitted, since this will determine when the frames will be painted.

 

The remaining connecting rods have now been soldered up and rough polished. These still need final dressing and polishing, then the crankpin hole can be reamed out to the correct size, before fitting. The connecting rod will probabaly have to be fitted to the crosshead before the slidebars can be fitted to the loco's. So there are a number of things to be done before the final fitting can occur.

Edited July 2, 2017 by PhilMortimer

[Simond]

Phil

 

Thanks for the thorough write-up, I shall shamelessly plagiarise, with added thoughts for fun, of course!

 

Still waiting for my new frames, meanwhile making gentle progress with Tre Pol & Pen (on the other channel)

 

Best

Simon

[PhilMortimer]

Thanks Simon,

 

I'm sure a "proper" engineer like yourself can do this far better than i have, but so far it has worked for me. With several of these loco's under construction or recently constructed, It's interesting to see the different ways various people tackle the various issues they have with assembling with these loco's. 

 

P

[Simond]

I like that, "a proper engineer".

 

Now you've given me something to live up to!!!

 

Best

Simon

[PhilMortimer]

Not a huge amount of progress this wekeend - my presence was required for other jobs (chores?). Apparently, there is a life away from railway modelling. However, I did get the chance to laminate the remainder of the slidebars, reducing pile of 24 rough cut ones to 12 soldered ones. These were subsequently filed and rough polished over the rest of the weekend (between other jobs) resulting in a smaller pile of 12 completed smooth bars. These need final polishing, and then I hope to attach them to the cylinder ends as described previously in the next few days.

[PhilMortimer]

Second pair of slidebar / cylinder end assemblies assembled last night. I find it takes me about 2hrs to do a pair, including fettling and polishing to a smooth sliding fit. So that is two more evenings to complete the lot. Still, once the intial soldering of the bars to the cylinder ends is done, I can do the cleaning up whilst watching a film, as it is sort of mindless (the cleaning up, not the film, though sometimes that can be mindless as well!). The only difference I did in this round was that after blobbing on the solder with the iron, I heated up the cylinder end casting with the flame to remelt the solder and allow it to flow through the joint. This created a much neater join of the slidebars to the cylinder end, with less cleaning up. Always learning.........

Edited May 23, 2017 by PhilMortimer

[PhilMortimer]

Third pair of slidebar / cylinder ends assembled and fettled. One of the pair went OK, the other was difficult and in the end I blew it all apart and set it up again from scratch. all works fine now and both sets slide easily. One more pair to assemble and then thats the lot. Possibly not tonight, since I have other things to do that must take precendence. After completing all four pairs of slidebar assemblies, I will then start trimming the slidebars of each one down in length to fit the motion bracket. (The slidebars were made deliberately over length to allow for adjustment when fitting). Much trial fitting will result until success is achieved, so it will take a while to complete this job.

[PhilMortimer]

Final pair of slidebars assembled last night and part polished. Still need to do a little fettling and cleaning up of this pair, but ran out of time. Will finish up tonight.

Glad to get this job out of the way. Now to make them fit the power units!