Phil Mortimers 7mm WorkBench - Mercian Vivian Style Garratt

[PhilMortimer]

Thanks Simon.

 

The depth is close to my calculation. I used the distance from the back of the stepdown in  the frame and made that about 7.5mm. However, making a jig of those dimensions, the pivot point was a little out, so I need to check things again. The discrepancy is small, but noticable and could be due to slop in the alignment of various parts of the frames, expansion link pivot points,  etc. Need to check further!

[PhilMortimer]

Work has been continuing, but there have been a lot of (non-railway) distractions - primarily work!

 

The hind units are now running - I have had to grind some metal from the crossheads to avoid clashes with the radius rods, which are in the down position on the hind units. The font units have been adjusted to match for consistency, although the radius rods are up on those units. The radius rods are set in the position approximately halfway between full gear and mid gear, above or below the pivot point depending upon which direction the unit has been set for. The idea of having the valve gear adjustable has been dropped - there are just too many problems with this loco to get that to work to my satisfaction.

 

I have travel over the next week or so, so a few days break from these loco's will actually be quite nice - I feel like I'm bashing my head against a wall with them at times!

[PhilMortimer]

Back from the Great Frozen North, which was actually quite warm, although the lakes were still frozen and need a few more weeks before they open up.

 

Anyhow, last night was spent getting the VG for the final power unit working. All units now need the VG fettling, as there is a bit more slop in it than I would like in some sets. so much work, but not very photogenic. However, everything is rolling smoothly.

 

P

[ERIC MITCHELL]

Well you guys have been busy, sorry i have not been around ive been slowly working on the garrets and my saint chassi is ready to be painted and put to gather i will postsome photos in the next day or so 

 i have had to put most of my time on working in my dark  room for a new exhibition hence the not done much work in the workshop.

but love what you are doing phil 

not sure if my work will match yours 

[PhilMortimer]

Eric,
 
if you have a thread, we would love to see it.
 

Everyone,

 

Slowly plodding on with my two builds. Basically been tidying up the valve gear to make it reliable. In same cases, a couple of steps back before going forward again (i.e. in advertantly unsoldered one slidebar of one of the units, so needed replacing (though runs a lot smoorther now!) and one of the expansion links came apart and needed putting back together again (needed to find the jig for that one!).

 

Now replacing the temporarty pins that hold the radius rods to the expansion links with something a bit more permernant (but which can still be removed to dismantle the VG for removal).

 

So nothing spectacular or photogenic, but plugging along.

Edited April 30, 2018 by PhilMortimer

[PhilMortimer]

The VG on all units is now running satisfactorally. All of the temporarily pinned points (where the VG can be dismantled for removal) have now been replaced by threaded screwed points, so the whole lot won't fall apart when it runs!. I still need to get the proper bolts, but for now it is good and the loco's roll smoothly. extensive playing testing has been performed!

 

However, I'm still having problems fitting and getting the lift and drop links to work correctly. Part of the problem is that the lift/droplink pivot is very close to the expansion link, and when the radius rods are down (forward gear, hind units), the pivot gets wacked by the expansion link. I have tried thinning down the bolt head, but am still having problems. Its not so bad on teh forward units, which are set in reverse, as the piviot is higher and should just clear the expansion link. I've noticed that others who have built these loco's have also had problems and on some case, just omitted them! That could work, as they are somewhat hidden. But it would bother me. I notice that Giles' loco has them fitted, so it can be done. 

 

I'm still working on this problem, but am having to set it aside at times in case I launch a power unit into orbit! the Mojo has suffered a bit. I have a couple of suggestions, some of which involve a bit of skullduggery, but since they are largely hidden, may work.

[Simond]

Hang in there buddy...

 

I’m sorry not to be able to offer constructive help, but I’ve made no progress on the Garratt, and my vg experience on the Duchess could not be described as exemplary, more sort of pragmatic.

 

I will have a look if I get a chance, and if possible, I’ll model it in 3D cad. It may help, though I’m neither betting that it will, nor promising that it’ll be this week, as I have some work travel to do.

 

Best

Simon

[Giles]

I really can't quite remember what I did....

 

Here's one of the better photos of the lifting link

 

2017-12-07_06-44-52 by giles favell, on Flickr

 

Garratt Valve gear by giles favell, on Flickr

 

Screenshot_20180508-182221 by giles favell, on Flickr

Edited May 8, 2018 by Giles

[Giles]

It sounds to me that either the shaft for the lifting links should be a touch further forward, the lifting arms need to be longer (to save moving the shaft) or there is too much movement on the expansion link - suggesting that the return crank is describing too large a circle, and needs resetting nearer the axle centre.

Edited May 8, 2018 by Giles

[Giles]

The front engine with lifting links down.

 

2018-05-08_06-41-44 by giles favell, on Flickr

 

2018-05-08_06-43-01 by giles favell, on Flickr

Edited May 8, 2018 by Giles

[PhilMortimer]

Thanks both - those pictures and suggestions are extremely useful, as are the pictures from Gile's thread.

 

I haven't been on line for a couple of days, but I have now cracked the issue (I think). Part of the complexity is the fact that I need the VG to come apart for painting of the chassis, and so incorporating the joint was "interesting". Close examination will show the fudges I've had to use, but if your nose is that close to my loco, back off! Anyhow, I think I know how to do it now and just have another 7 to do (3 more rods down and 4 rods up, the latter being easier to do).

 

Thanks once again.

 

P

[PhilMortimer]

Quick update.

 

The lift links and droplinks all four VG sets on the rear power units (rods down) are now fitted and working. This essentially completes the VG work on the hind units. I now need to do the same for the front units (rods up), but now that I know what I'm doing, expect this to be easier and proceed faster. The build work on the power units is coming close to completion - yay!

 

Photo's and movies to come once the gearboxes are built up and installed. Also, need to get a rolling road - any suggestions as to which is best?

[PhilMortimer]

Time for an update. Posts have been a bit sparse, as there hasn't been much visible progress to report. After all, doing eight sets of valve gear gets a little repetitive. But I have now completed seven of the eight sets by fitting the final parts, the lift and drop links. The eighth is underway, but i have lost the lift link to the carpet gods, and so am having to fabricate a new one. Just need some time to do it. Of course having done so, I will then rediscover the original.......

 

The picture below shows the lift and droplinks held together with a 14BA bolt. I had to slightly alter the shape of the droplink from that of the real thing, but it is not to obvious once fitted. And the picture is a significant enlargement. When fitted, the bolt will be cut back and the head reduced in size. The lift link (to the rear) is threaded 14BA and so the whole is held together with the bolt slightly loose to allow the two parts to pivot and flex. The bolt (like others in the VG) will be secured in pace with a dab of varnish, enough to hold things in place but easy enough to undo.

 

. by Phil Mortimer, on Flickr

 

The next two photo's show the lift/droplink assembly being fitted to the weigh-shaft and the remainder of the valve gear. The weighshaft is formed from 0.9mm brass rod, sleeved with brass tube to bulk it up and give it some additional rigidity. Some significant effort was involved to determine and mark out the correct position for the weighshaft on the frames. This was necessary to ensure that everything would move properly with no binding as the wheels rotated and the VG oscillated. To achieve satisfactorily free movement, I cheated and made sloppy joints where the droplink attaches to both the radius rod and the lift link . Not proper engineering I know, but frankly, not noticeable and a damned sight easier when dealing with all the other issues associated with this build. The droplink is held to the radius rod with a soldered dress makers pin passing through an overlarge hole in the rod. The link is thus permanently attached to the rod, but can be disconnected from the liftlink by undoing the previously seen bolt, so allowing the rod to be removed for painting and maintenance.

 

. by Phil Mortimer, on Flickr

 

. by Phil Mortimer, on Flickr

 

The brass wire in the above two pictures is overly long to enable correct positioning for soldering and fixing of the lift link. It is subsequently cut short once everything moves freely and the end dressed.

 

Finally, here is a picture of the completed VG from one of the leading power units (radius rods and lift links up, in reverse).

 

. by Phil Mortimer, on Flickr

 

All of the bolts will be cut down in length and the heads reduced in size when the VG is finally re-assembled after painting of the chassis units. But t present, it allows the movement to be checked for binding while it is being assembled.

 

With the completion of the valve gear, the power units are almost complete. All that is required now is fitting of the motor/gearbox, the drawhooks and the brake assembly (still awaiting cross-shafts). Hopefully, the pace of assembly will then pick up a bit as we move towards completion.

[PhilMortimer]

As expected, I had just almost completed makng a replacement lift link when the carpet gods decided to give back the original. Just bl00dy typical!!

[PhilMortimer]

The valve gear is complete on all eight units! And it all functions!

 

Just fitting the draw hooks now so that they can be removable for painting. Also, starting to assemble the gear motor mounts.

[PhilMortimer]

One quick photo showing the drop link attached to the radius rod / combination lever assembly. This is attached with a dressmakers pin, soldered on the inner side of the VG and cut short.

 

. by Phil Mortimer, on Flickr

 

Work on the drawhooks continues, with the shafts having been drilled out to accept the attachment / pivot point. I intend to solder some reinforcement to the shaft in the area of the pivot / attachment point. Basically for the same reason that I'm also beefing up the attachment points - as some one once said, with these locos being garratts, you never know who is going to hang an unreasonably long train on the hook to see what it can pull and you don't want it parting company with the loco! (Very embarrassing!).

[PhilMortimer]

OK, first time trying to upload a video, so lets see if this works. Two rather boring video's of both loco's being tested for ease of rolling and smooth action of the valve gear. Appologies for the cluttered workbench background - this is actually tidier than normal. Next time I will try and get a blank background to help highlight the loco's

 

First up, both garratts undergoing rolling test on my short length of test track on my (rather cluttered) work bench. Motor and gears are not yet fitted, so power supplied by Dapol 3F Jinty

 

 

Next up, close up of one loco during rolling test, showing movement of valvegear.

 

 

not great vidio's, but shows that progress has been made. On to the bunkers!

Edited June 3, 2018 by PhilMortimer

[Giles]

Good stuff! Always nice to see movement - congratulations!

[Simond]

Great step forward Phil, they look really lovely.

 

Mine is languishing part built waiting for me to get round to milling the chassis units that I have pretty much completely redrawn on Solidworks. For which, I need to order the mills, and the brass...

 

Meanwhile, the laser & the Dutchess are keeping me entertained.

 

Best

Simon

[Mike Boucher]

OK, first time trying to upload a video, so lets see if this works. Two rather boring video's of both loco's being tested for ease of rolling and smooth action of the valve gear. Appologies for the cluttered workbench background - this is actually tidier than normal. Next time I will try and get a blank background to help highlight the loco's

 

First up, both garratts undergoing rolling test on my short length of test track on my (rather cluttered) work bench. Motor and gears are not yet fitted, so power supplied by Dapol 3F Jinty

 

 

Next up, close up of one loco during rolling test, showing movement of valvegear.

 

 

not great vidio's, but shows that progress has been made. On to the bunkers!

 

 

       

[Night Train]

Epic work.

[PhilMortimer]

Thanks.

 

Back on base now having had to deal with the craziness of NYC for a few days,

 

I have been assembling and experimenting with the motor / gear mounts as is seen below.

 

. by Phil Mortimer, on Flickr

 

The pair on the left use the motors and gears as supplied with the kit. The gear ratio is 40:1, and uses Scale Link gears and a Mashima motor (I think it is a 1620). This works well, though the N/S of the motor mount is a bit thin and flexible and the bearing holes need to be reamed out to fit. In addition, as designed, the gear is offset from the worm, which to me seems crazy, as it puts the meshing on just one one side of the gear wheel. This causes the interaction between the worm and the gear wheel to run along the edge of the gear teeth, and in my mind, the load on the gear teeth was on a much smaller area and could potentially lead to stripping of the gear teeth. This was pretty obvious in that it ran smoother in one direction than the other. However, by filing down one bearing on the mount and adding packing washers, it was possible to centre the gear wheel with respect to the worm, so that the meshing was along the center of the gear teeth. This improved both the meshing characteristics (and reduced the chance of stripped teeth) and the running - it runs equally well in both directions and is a lot smoother. Result! The only problem with this setup is that the 1620 runs rather fast (13500rpm at full speed if I recall) and with the 40:1 gear ratio, the speed is rather fast for what is essentially a large shunting engine. However, this is what is going in the loco destined for the client as that is what he asked for.

 

For my loco, I want better low speed characteristics. Giles experimented with fitting a Markits 54:1 gear mount mated with a slower running Mashima 1824 motor. The 1824 is virtually impossible to obtain these days, but I did obtain two 54:1 boxes to experiment with. When mated with the supplied 1620 (top right of photo), the speed is better but still a bit fast for my liking. However, it is a possibility. I have also been experimenting with a Taff Vale motors 1833 equivalent, which runs at a slower speed. This combination is better, though the motor is not as vibration free as the Mashima. However, the motor is too large to fit in the model. I have instead ordered a smaller 1527 version, which is supposed to have similar running characteristics. I am waiting for these to arrive to experiment further. The Markits gear mount is much stiffer than the one etched as part of the kit, but it is also much larger. Since there are some extra motor mounts supplied with the kit, I may look at transplanting the Markits worm and gear into the Mercian motor mount and fitting the 1527 to see if I can get a smaller motor gear package. This is likely to involve some adjustment of the motor mounting screws and a successful outcome is not foregone. However, since there are extras supplied as part of the kit, it is worth trying. I have done some initial trials and it looks like it should work, though some grinding away of the mount may be needed to accommodate the larger gear wheel.

 

In the meantime, in the midst of all this experimentation, I have also started to assemble the frame work for the rear bunkers, as seen below.

 

. by Phil Mortimer, on Flickr

 

It was a bit of a faff to bomp out the rivets - the half-etched markers are way to large to aid centreing of the punch and keeping things straight was tricky. However, looking at the real thing, it appears that some of the rivet lines are a bit wavy as well!. Hopefully some grime will help.

Edited June 12, 2018 by PhilMortimer

[PhilMortimer]

A few more pictures showing the bunker framework has had the attachment points added and is temporarily fitted to the rear power units. The wrappers will wait until I have gotten the motors installed, as the open framed nature will aid getting the correct motor / gear positioning. There isn't a lot of space under that bunker. However, it does start to show the final outline of the loco.

 

I need to check the lubricator issue. I think on William Francis, it had just one lubricator on the hind unit, meaning that I need to fill the hole in the wrapper on the RHS. But I'm not sure about Sneyd Colliery #2.

 

Still to do the forward tank framework, but will have to wait a day or so.

 

. by Phil Mortimer, on Flickr

 

. by Phil Mortimer, on Flickr

 

. by Phil Mortimer, on Flickr

 

. by Phil Mortimer, on Flickr

[PhilMortimer]

We have power! Yesterday saw the 1620D/ 40:1 motor gear combinations fitted to the power units of the first loco. Some trials and errors were made in sorting out a torque reaction arm, but I think I have now worked out how to do it so that the motor gearbox can be removed from the chassis for maintenance and painting. Power has been applied using flying leads and everything rotates nicely, though I had to put some bluetack on the nut holding the return rod to the return crank, to prevent it unscrewing itself. This will be resolved upon final assembly. personally, I feel that this combination is still a bit fast for a shunting engine, with a maximum usable speed achieved at about 40% . However, maybe adding a suitable resistor will slow things down a bit. I just need to secure the motors to the torque arm and then it is time for track trials! The bunker fits nicely over this motor / gearbox combination.

 

Pictures and possibly video's to come later

 

PM

[Simond]

Phil,

 

A resistor will just get hot... assuming you are not going DCC (which has a programmable Vmax), then might it be reasonable to put the motors in series?

 

Best

Simon