Phil Mortimers 7mm WorkBench - Mercian Vivian Style Garratt

[ERIC MITCHELL]

Opps,

 

Simond 

[Simond]

Eric

 

no worries - I've been called much worse things than my name!

 

Please post photos of you model.

 

I am optimistic that I will be restarting my model soon. 

 

atb

Simon

[PhilMortimer]

Eric,

 

Please post photo's of your loco's - the more the merrier.

 

Todays news is that all eight return cranks have been made up and installed.

 

. by Phil Mortimer, on Flickr

 

And a closer view showing the 90 degree position offset to the main rod.

 

. by Phil Mortimer, on Flickr

 

As with the rest of the valve gear, you're on your own here with regards to instructions on building these up and fitting them. No doubt there are other ways of doing it, but here's how I did it.

 

Basic assembly of the return cranks is pretty easy, with a 2 layer lamination forming the body of the crank. A 12BA bolt was placed through the crank end and secured firmly with a nut (coated in marker pen so it did not become soldered to teh bolt or crank. After tightening down, the rear of the bolt was solderd firmly to the crank and then the bulk of the bolt head ground back with a dremel tool. This is to avoid the bolt head clouting the connecting rod as it rotates.

 

. by Phil Mortimer, on Flickr

 

The crank then has to be attached to the retaining bush that holds the rods to the crankpins. Like many others, I have modified my crankpins by tapping out my wheels 10BA and replacing the supplied 12BA nuts and bolts with 10BA csk bolts screwed in from the back (and locked with Loctite). Two Slaters crankpin bushes tapped 10BA are used to hold the rods on. The inner one is reduced in height so that it is slightly greater than the thickness of the rod (+10thou). This is installed on the crankpin with the "brim" facing the wheel and screwed sown tightly against the wheel face until it can move no further. The other tapped bush is used to retain the rods on the crankpin, as it is installed "brim" out. When screwed down against the first bush like a jam-nut, it traps the rods on the crank pin. The return crank is soldered to the outer face of the brim of the outer bush.

 

Before soldering the crank to the outer crankpin bush, it is important to ensure that free rotation of the wheels with the rods on is achieved. Once this is done, the outer bush is removed, the outer face of the brinm polished and then tinned with 100 degree solder. Once cool, it is re-installed on the crankpin (which has been coated with marker pen) and screwed down tightly on the crankpin against the inner bush as far as it will go. Then the crank is placed in position atop the bush, ensuring it is correctly aligned at bogh ends (centered on the crankpin and the outer end at 90 degrees to the crankpin). This can take some time to get right and requires at least 5 hands! If its not right, walk away and come back to it fresh. It's worth getting the positioning correct. Once all is correct, hold the return crank in position with a cocktail stick or simmilar, and just momentarily touch the edge of the crank and bush with a hot soldering iron to tack the return crank to the bush. By using 100degree solder and pre-tinning both parts, some of the solder will melt quickly enough and then re-solidify before enough heat gets into the crankpin and melts the Nylon wheel centre. Allow to cool and then breathe! Air is your friend!! I don't have any photo's of this as I needed all my hands and concentration. Once cool, you should find that the crank is sufficiently soldered to be able to wind the bush off the crankpin. I ususally check the bush is correctly centered on the crank by holding it in a vice using the overlong bolt and giving a good examination. If the bush is not quite in the correct position, no matter, just heat the return crank up and give it a nudge in the correct direction. As long as you don't rotate the bush whilst the solder is molten, you will be fine. I normaly allow to cool and then apply a small clamp to the bush and crank, before re-heating the solder one final time. This allows the bush to "sit-down" on the crank if it isn't quite, and ensures the crank is at 90 degrees to the axist of the bush.

 

All being well, we now have a return crank that can be wound onto the crankpin and will stop in the correct position.

 

. by Phil Mortimer, on Flickr

 

. by Phil Mortimer, on Flickr

 

So now to assemble all the rods. Firstly, here is a sluightly blurry picture of the crankpin (sorry about the blurriness) with the inner bush fixed in position.

 

. by Phil Mortimer, on Flickr

 

 

The coupling rod is then fitted - The close fit of the rod on the bush can be seen in the photo below.

 

. by Phil Mortimer, on Flickr

 

A spacer (not shown) and then the connecting rod are then fitted - note the gap between the rod and the crankpin - this will be taken up by the return crank bush.

 

. by Phil Mortimer, on Flickr

 

Finally, the return crank is screwed on and into the correct position. These loco's have a shim washer on the return crank bush to reduce sideplay in the rods.

 

. by Phil Mortimer, on Flickr

 

Check for free rotation and sit back and smile! It took on average about 30 mins to fit each return crank to my satisfaction. Most of this was getting the alignment correct prior to tack soldering. For the heck of it, I did temporarily fit one of the eccentric rod / expansion link assemblies and these rock back and forth corectly as expected with the rotation of the wheels. Indeed, I even fitted one of the radiius rod / valve rod assemblies and yes, everything does oscilate as it should. No photo's I'm afraid. However, I think the radiius rod is too long, as it jams against the valfe guides at certain points.I will need to revisit this when i get back from Montana.

 

OK, confession time. I will admit that did have a problem with one of the crank pins when i was distracted by a leaping cat just as I was tacking one of the return cranks to the bush, and thus lingered with the iron a touch too long. This softened the nylon and tilted the crankpin afew degrees from the verticle, with the result that my free running power unit suddenly ran like a three legged dog. Lots of rude words were said, visions of having to make a replacement wheel were had and I put the whole thing away for 24 hrs in case I launched it into space. After carefully examining the (now removed) wheel the following day and some careful measurement, I found that most of the softening had occurred at the front of the wheel and that the aperture at the back was still in the correct position. Thus I was able to carefully fill the front of the crankpin hole and re-tap the from the rear using my vertical tap, thus restoring the crankpin geometry and smooth running of the chassis. I've fitted numerous return cranks this way in the past and this is the first time this has happened to me - I blame the cat (who is supremly unconcerned)! Still all is well now.

 

The culprit!

 

Sleepy Stew by Phil Mortimer, on Flickr

 

However, I think this, together with the deart of instructions for the VG, does show the value of learning how to problem solve building a kit and developing one's own way of doing things. Over on another thread there has been discussion about why people modify kits from the designers intentions. My view is that by tinkering with and improving kits, better models are produced and experience is gained that allows problems such as the one I faced to be overcome and resolved, without having to obtain new parts. And whilst I'm a bit red faced about the screw up, I'm pleased with myself that I was able to overcome it and fix the issue, as well as having 8 nice return cranks all in their intended positions.

[Simond]

Nice job Phil,

 

I’m sadly as far from getting on with mine as I was about 11 months ago, but fingers crossed, this year.... it’s not a race after all.

 

I had conjectured a route to doing the return cranks very similar to yours, with the thought that I could simply shorten one or both bushes, or thin the washer between them, to get the correct alignment of the crank. Obviously starting with it soldered on in roughly the right place will help. Unlike the cat.

 

Ours is reasonably well mannered, and is frequently content to lie on the back of the sofa next to my modelling chair, on the basis, or hope of an occasional stroke or scratch of his neck. He hasn’t shown any inclination to help with the soldering.

 

Best

Simon

[laurenceb]

The look on his (her) face says it all!

[Mike Boucher]

Eric,

 

Please post photo's of your loco's - the more the merrier.

 

Todays news is that all eight return cranks have been made up and installed.

The crank then has to be attached to the retaining bush that holds the rods to the crankpins. Like many others, I have modified my crankpins by tapping out my wheels 10BA and replacing the supplied 12BA nuts and bolts with 10BA csk bolts screwed in from the back (and locked with Loctite). Two Slaters crankpin bushes tapped 10BA are used to hold the rods on. The inner one is reduced in height so that it is slightly greater than the thickness of the rod (+10thou). This is installed on the crankpin with the "brim" facing the wheel and screwed sown tightly against the wheel face until it can move no further. The other tapped bush is used to retain the rods on the crankpin, as it is installed "brim" out. When screwed down against the first bush like a jam-nut, it traps the rods on the crank pin. The return crank is soldered to the outer face of the brim of the outer bush.

 

Before soldering the crank to the outer crankpin bush, it is important to ensure that free rotation of the wheels with the rods on is achieved. Once this is done, the outer bush is removed, the outer face of the brinm polished and then tinned with 100 degree solder. Once cool, it is re-installed on the crankpin (which has been coated with marker pen) and screwed down tightly on the crankpin against the inner bush as far as it will go. Then the crank is placed in position atop the bush, ensuring it is correctly aligned at bogh ends (centered on the crankpin and the outer end at 90 degrees to the crankpin). This can take some time to get right and requires at least 5 hands! If its not right, walk away and come back to it fresh. It's worth getting the positioning correct. Once all is correct, hold the return crank in position with a cocktail stick or simmilar, and just momentarily touch the edge of the crank and bush with a hot soldering iron to tack the return crank to the bush. By using 100degree solder and pre-tinning both parts, some of the solder will melt quickly enough and then re-solidify before enough heat gets into the crankpin and melts the Nylon wheel centre. Allow to cool and then breathe! Air is your friend!! I don't have any photo's of this as I needed all my hands and concentration. Once cool, you should find that the crank is sufficiently soldered to be able to wind the bush off the crankpin. I ususally check the bush is correctly centered on the crank by holding it in a vice using the overlong bolt and giving a good examination. If the bush is not quite in the correct position, no matter, just heat the return crank up and give it a nudge in the correct direction. As long as you don't rotate the bush whilst the solder is molten, you will be fine. I normaly allow to cool and then apply a small clamp to the bush and crank, before re-heating the solder one final time. This allows the bush to "sit-down" on the crank if it isn't quite, and ensures the crank is at 90 degrees to the axist of the bush.

 

All being well, we now have a return crank that can be wound onto the crankpin and will stop in the correct position.

 

 

Great write up.  I'm sure what I learned there will be of use when I build my first outside-valve-geared locomotive.  (which is 2 or 3 down from the top in the queue right now...)

 

Are you going to get to Brampton this spring?  I'm considering making the 8 hour drive from MA.

Edited February 23, 2018 by Mike Boucher

[PhilMortimer]

Hi Guys,

 

Thanks for the replies. Sorry for the delay in getting back to you - I had a quick trip to the Rockies and squeezed in a trip to what I think is probably my favorite place in the world, where there is fortunately very little internet access!

 

C24D3DDA-0370-4411-B2C6-B70498B1376C (2) by Phil Mortimer, on Flickr

 

 

Old_Faithful_Yellowstone022018 by Phil Mortimer, on Flickr

 

 

As for the cat, he (Stewart) is the most needy and clingy of our three. The others will snooze on the carpet in close proximity to me when i'm working, but he has to be involved. He has terrible seperation anxiety and we suspect that it has some thing to do with his past (he's a rescue and so we don't know his origins). All I can say is that he has a lot of charachter and impeccable timing - he always decides to come up onto my lap just when i'm really concentrating or working on a really difficult solder joint....

 

Hopefully will get back to the WB in the next day or so.

 

P

Edited February 27, 2018 by PhilMortimer

[PhilMortimer]

Mike,

 

Glad it was useful.

 

Do you have any more information on the Brampton meeting (I assume that this is Brampton, ON?). I wasn't planning to go, but it sounds interesting.

Edited February 27, 2018 by PhilMortimer

[Mike Boucher]

Mike,

 

Glad it was useful.

 

Do you have any more information on the Brampton meeting (I assume that this is Brampton, ON?). I wasn't planning to go, but it sounds interesting.

Yes, the "Great British Train Show" in Brampton, ON at the end of April.  http://www.theplatelayers.org/gbts2018/gbts2018poster002.jpg

 

I've never been myself, but it does sound interesting.  I believe other members of the "US Gauge O Guild NorthEast" group (AKA "USGONE") are planning on going, and I'm fairly certain one is going to bring is 7mm layout to exhibit.

 

I'm strongly considering going just to see what its all about, and possibly to help operate the layout.  If I never go, I'll never know if it's worth the drive...  They only hold the show every other year, so if I don't go this year, I'll have to wait until 2020.

 

BTW - the layout is based on the Southern, and the owner has some very nice kit-built Southern locomotives.  He has a beautiful "Schools" which runs like a swiss watch.

 

Mike

[PhilMortimer]

Thanks Mike, sounds interesting.

 

Hmm, I wonder if I can persuade my wife that she wants to go to Toronto at the end of April?

 

I doubt I will have the garrats completed by then though.

 

Cheers,

 

P

[Mike Boucher]

Thanks Mike, sounds interesting.

 

Hmm, I wonder if I can persuade my wife that she wants to go to Toronto at the end of April?

 

I doubt I will have the garrats completed by then though.

 

Cheers,

 

P

Hi Phil,

 

I would certainly be interested in seeing them in whatever state of completion they're in.

 

Often, I think I have more fun building than running, so seeing a partially built project can sometimes be more interesting than watching it roll down the track.

[Marshall5]

Love the Jellystone pics Phil and  I hope you paid the toll - half a bale of alfalfa or a bag of Purina cow chow at current exchange rates I believe. A bit chilly there at the moment, I read that it was minus 38F in West Yellowstone one day recently. I know that spot well from our visits - as long as my better half gets her 'geyser fix' every year I get no complaints when we go 'playing trains'!

Cheers,

Ray.

[PhilMortimer]

Hi Ray,

 

Thanks. Yes, we know Yellowstone well. (Indeed, we got married there). However, this was the first time there in winter. It was a tad chilly - I think the lowest was -5 (F), but with wind, so felt a heck of a lot colder. -38F is just too cold to do much!

 

Back to the garratts. The next step is going to be beefing up the expansion link mounting brackets. These were fitted to the motion bracket some time ago, but the kit only supplies a single N/S etch for each (12 thou  believe), which makes it a bit weedy. This is not just in looks, but also in actual strength - they keep getting bent with handling of the chassis units. This will cripple smooth running and needs to be dealt with, whislt also improving the appearance. Ideally, the kit would supply multiple layers that could be laminated together, but it doesen't. So the plan here is to remove the brackets one at a time from the motion bracket, laminate them to some 25thou brass strip, and rotary sand, cut and file the brass back to the shape of the N/S bracket. I will try a couple either tonight or over the weekend to see how I get on. All being well, it will make a much more substantial bracket that will not be damaged or bent so easily. However, I have 16 to do, so it might take a bit of time. However, the pay off in improved looks, strength and reliability will be worth it.

 

I have also ordered my next build - a Hunslet Austerity from the same stable to go with the Garratt. I'm looking forward to finishing this one up and getting on with it. Will try and go for a CSB sprung chassis on this one.

Edited March 1, 2018 by PhilMortimer

[PhilMortimer]

OK, that plan isn't going to work! I removed one of the expansion link brackets yeterday and laminated it to some brass as described above. Even using a rotary tool, it takes ages to sand and grind things back to the original shape and the result isn't great (though I still need to attack it with the needle files). Plus, I need to make 16 of the things and the time to do just one makes it not worth it.

 

So I need to rethink this. I will try and see if Mercian Trevor will sell me the valve gear frets - that way I can double up the expansion link brackets. Otherwise, i need to come up with a plan B!

Edited March 2, 2018 by PhilMortimer

[ERIC MITCHELL]

Hi Simon, Phil, 

ive been away 1 week in London to meet up with my daughter who is over from states,this week and it has been just to cold to do much in work shop (shed) tho i have now bought a heater ! ive just had a burst pipe (grrrrrr) no damage but means getting into the loft of the out building as i need water for my darkroom. Iuse my spent fixer to wash and clean away flux residue 

once sorted will organis pics i do not have digi camera so will be by my phone.

your work on crank gear is great Phil 

.

my intention is to hold up on doing any more work on the engine units  (I have all but finished the bunkers ) and start on main frame well it is doing my head in this kit ! 

i have also got a GWR saint class loco built way back in the 80s ive got the chassie off and cleaned wheels but brake gear to remake  

[Simond]

Phil,

 

A thought, can you solder a series of sheets of brass together, and one of the brackets on top, and then fret-saw out the whole series in one? Then drill for the pivot, and then unsolder & clean up?

 

Eric,

 

Leave your bogies for a week or two, I’m making progress again, I may be able to help.

 

Best

Simon

[PhilMortimer]

Thanks Simon, but I think I have a plan B.

 

Plan B is of course reverting to plan A! After thinking about it a bit more, I couldn't see anything fundamentally wrong with the initial idea except that it was going to take for ever to file the brass back to the template. However, on the way home, i stopped by the hardware store and they had some Dremel milling cutters of different sizes. Perfect. I purchased a few and some fresh brass strip, and went home to try things out again. The only difference this time is that I'm using 16thou brass strip. rather than the original 25 thou x 1/4". This is because the store didn't have any 25 thou in stock. I would have prefered the wider, but as it turns out, it doesen't make a great deal of difference in the strngth of the finished item. The other difference is that I'm soldering the etched N/S part directly to the strip, rather than cutting the strip into small sections for each etched part. This makes manipulation of the work piece easier.

 

So, on Friday evening (it was blowing a gale, so we were staying home, a N/S bracket was removed from one of the power units and laminated to the brass strip, carefully aligning the edge that fits to the motion bracket with the staight edge of the strip.The soldering was cleaned up and the original etched N/S bracket coated with marker pen so as to highlight the edges of the original.

 

. by Phil Mortimer, on Flickr

 

The brass strip was firmly clamped to the workbench and then using the milling cutters in the Dremel, the excess brass strip was carefully nibbled away, until almost reaching the edge of the original etched bacrket that is acting as the template. The strip was securely fixed to the work bench and I used the rotary tool freehand. The hole for the expansion link trunnions was drilled out and the bracket almost completly milled out until held to the brass strip by a small tab.

 

. by Phil Mortimer, on Flickr

 

Whilst still affixed to the brass strip (to act as a handle), the remaining brass was then hand filed away back to the edge of the N/S template, untilusing a variety of diamond coated needle files. The edges were then smoothed by running a small diameter rotary file along the filed edges until a good smooth surface was obtained. The (now much thicker) laminated work piece was then released from the brass strip, the tab filed away, the marker pen was cleaned up from the finished bracket and it was ready for re-installation. Unfortunately, I forgot to take a picture of the finished item, but will do so with the next one I do. It looked OK.

 

Because the edge of the bracket that affixes to the motion bracket was aligned with the edge of the brass, no milling or filing work was needed on this edge and so assuming the alignment for the original lamination was correct (and oh, did I check it numerous times!), the completed work piece should sit correctly back down on the motion bracket as before. There are two small protrusions from the original N/S bracket and these match with holes in the motion bracket to give correct alignment. Thus it was relatively easy to solder the now beefed up expansion link bracket back onto the motion bracket and get the alignment correct, espescially, since I could use the trunion bearings to give an additional alignment reference. (Remember, I only removed one expansion link mounting bracket at a time from the motion bracket, so the other was still fixed in place and could be used as a reference by running a wire pin of the correct size through the trunion bearings. It also aided manipulation of the small part into the correct orientation in all planes,). Soldering was accomplished using Carrs 189 degree solder paste and the RSU. The thicker bracket now sits far more securely on the motion bracket due to the greater footprint, which also makes it easier to get it parallel to the frames,

 

The additional brass thickness is added to the INSIDE of the brackets, so one has to be careful to get the correct orientation of the original N/S etched bracket when laminating the two together. Other than that, it isn't really difficult. The milling cutters speed things up and whilst you have to be careful to only cut off a small bit at a time, so far over the weekend I have finished and re-installed four brackets and so have completed the work for one power unit.  That still leaves twelve individual brackets and 3 power units to go! The first one took a while to do, as I was being cautious as to how much I cut back. However, with experience, I have speeded things up and now with no interruptions, I can do two a night, So whilst it will still be a bit tedious to complete all sixteen, it is a managable chore. Unfortunately, the weekend was busy dealing with fallen trees down and smashed fences due to bad weather, so much of the weekend was taken up with tree removal and fence repairs. Still, I'm pleased with the progress.

[PhilMortimer]

Still plugging on with modifying the expansion link brackets. Have now done three out of the four power units (12 brackets, removed, laminated, fretted out and replaced) and am working  on the 4th power unit (4 brackets still to go, though one is almost at completion). A couple more days should see this done and finished, then the expansion links can be fitted with the return rod to the eccentric crank. I will be honest here that other matters outrside railways have gotten in the way, so this has stretched out the time required to complete this task. Still, although i have gotten faster at fretting out the beefed up brackets once the originals are laminated to the brass strip, I will be glad to see the back of this job.

 

A couple of cruelly enlarged pictures showing the beefed up brackets.

 

. by Phil Mortimer, on Flickr

 

Showing the bracket from the side of the N/S original.

 

 

. by Phil Mortimer, on Flickr

 

And from the back showing the additional brass lamination shaped to match the N/S original. These items are considerably smaler in real life than on screen, so any flaws also don't really show up. (In addition, this particular bracket is an inside one so isn't really visible).

Edited March 13, 2018 by PhilMortimer

[PhilMortimer]

Another pair fettled and fitted last night. Last pair to complete the set tonight hopefully! Then that job can be ticked off.

[Simond]

Phil,

 

I may be having a brainstorm, but we now have a 3D CAD model of a power bogie, redrawn from the plans that I got from you and others.

 

There is an issue with clearances behind the crosshead, so that will need sorting, and there’s a few other details to have a go at, but I’m optimistic that I can CADCAM it directly to brass. It’ll be interesting to see how the expansion link brackets turn out. They’re pinned to the motion bracket with 0.6mm holes. That’ll be fun.

 

 

Sorry that the image is via paper problem linking directly to t’internet.

 

Best

Simon

[PhilMortimer]

Darn! That's a nice set of plans for a nice set of frames! It looks like it should be much stiffer and easier to align than the ones I've built. I should have waited and asked you to do me a set!

 

Anyhow,I aim plugging on with my two loco's ( 4 power units). I made and fitted the final two expansion link brackets tonight, for which I'm very pleased. I'm now going to turn in knowing that lot is done and that I can now turn to fitting the expansion links themselves.

[Simond]

Thanks Phil,

 

The key difference between my frames & yours is that mine are virtual, and yours already run!

 

I’ll be keeping up the story on my Loco loco thread,

 

Best

Simon

[PhilMortimer]

Yes, but yours will be sooooooo much better! And so much easier to assemble correctly and squarely without the excessivly wide alignment slots making positive alignment difficult. (I have to say that the finished chassis units are not as good as I like to get them, though I've tried my best with the kit supplied parts (in spite of the various difficultries such ass assymetry, wide alignment slots, etc.) and they do push along smoothly). Your ability to redraw them in CAD and then make replacements should yield a significant improvement in construction. What thickness brass are you intending to use?

 

I look forward to seeing the outcome......

Edited March 15, 2018 by PhilMortimer

[Simond]

Phil,

 

Thanks for the kind words! The recommended material for this is “engraving brass”, herewith an excerpt from College Engineering’s webpage

 

“Engraving Brass Sheet - CZ120

 

The following list is a list of our standard sizes of Brass Sheet in Engraving Brass CZ120 (Sometimes known as Leaded or Compo Brass), It is much easier to machine than ordinary brass (CZ108). “

 

It’s available in 28, 36, 48, 64, 104, 127, 187 & 250 thou.

 

(Strange, when buying non ferrous generally, I’ve found that it’s cheaper in inch sizes. I haven’t found engraving brass in metric, but I can multiply by 25.4...).

 

The model is currently drawin in 1mm sheet. It will not be a big issue to convert to 36 thou, 0.9mm, but the smallest cutters I have are 1mm, and I wonder if a 10% slack slot will be too loose. OTOH it will allow some space for the solder to flow.

 

There is another minor issue. The slots will all have a radius at the end because the cutter is effectively cylindrical. This is ok where the tab can be radiused to suit, of course, but in some cases it will be easier to get a very small file in the slot & square it up. Buffer beam slot for swinging 3-link hook, and hornways (it will be sprung) spring to mind.

 

Best

Simon

Edited March 16, 2018 by Simond

[Giles]

're the oversize slot. You could always plot a 10% dogleg into the slot, which will keep it tight and in place....