timb
Statesman
Posts: 512
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Post by timb on Jan 4, 2019 14:15:30 GMT
With some encouragement from Pete (doubletop) I thought I would post a photo or two of the Invicta I am building, also a good way to check if I can post photos.
A bit of background is due I suppose. I saw these castings and frames for sale on the well known auction site and thought them as a bit of a bargain - they turned out not to be such a bargain after all - explained later.
Sorry about the size of the picture....
Soon after the stuff arrived I thought I would build the frame, me being me I measured the so called "laser cut frame" as supplied and found the cylinder center line to be out buy 1/8", not surprising it was out because the laser had used a hacksaw and file to do the job! Good Start - not.
A visit to Blackgates (usual disclaimer, just relatively local) to get some fresh frame steel and I soon had frames for loco and tender along with buffers for both and I also took the time to make the eccentrics, sheaves and other bits and bobs.
The buffers were milled flat and square along with the angles for riveting.
The next job was the hornblocks five supplied, four of one type and another odd one(?) of course of the four that matched one had been butchered so all u/s. I milled hornblocks from solid MS bar which I happened to have and riveted the lot up before milling out the slots for the axle boxes.
Frame strecher/water pump bracket next, of couse this was not for this model and was 1/8 too narrow in its cast state so item 8 in the 'of no use' bin. I made this up from some brass bar - V cut then silver soldered.
The first supplied casting of any use was for the axleboxes and the axles and suspension were soon finished.
I will post this now so I can check if the photos work. More to come if there is interest.
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Lisa
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Post by Lisa on Jan 4, 2019 14:29:41 GMT
Hi Tim, the pictures are showing fine, and that looks like a fun little model, I look forward to watching it come together! Hope the auction lot wasn't too much of a loss, you never know what you're getting when buying second hand things blind. A little tip with imgur: If you want to shrink the images down a bit, imgur automatically generates thumbnails for every image; you just have to put an s, m, or l before the '.jpg' in the image url. Examples: Original: i.imgur.com/8YkHC3p.jpgSmall: i.imgur.com/8YkHC3ps.jpgMedium: i.imgur.com/8YkHC3pm.jpgLarge: i.imgur.com/8YkHC3pl.jpgUnfortunately, it doesn't work the other way with making small images bigger.
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timb
Statesman
Posts: 512
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Post by timb on Jan 4, 2019 15:00:52 GMT
Lisa, thank you so much, I thought they were a bit big! They show as pictures now when I try to edit, is there anything to be done for these or am I stuck with them?
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Post by Deleted on Jan 4, 2019 15:16:53 GMT
Hi Tim top of your post, right hand side you'll find the 'edit' tab...click that and you'll be able to add the character that you need to adjust your image size, IE if wanting large, place 'l' just before the dot '.'.. you can select 'preview' (bottom left) to check that it's the size you wish for. I tend to use 'large' for mine. It was thanks to Lisa that I learnt this some time ago.... Pete
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timb
Statesman
Posts: 512
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Post by timb on Jan 4, 2019 15:18:52 GMT
Brilliant! All sorted, thanks to Lisa and Pete.
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Post by doubletop on Jan 4, 2019 21:56:52 GMT
..... Soon after the stuff arrived I thought I would build the frame, me being me I measured the so called "laser cut frame" as supplied and found the cylinder center line to be out buy 1/8", not surprising it was out because the laser had used a hacksaw and file to do the job! Good Start - not. Tim Its looking pretty good. Perhaps they used these for cutting the frames? linkI did a Northumbrian for the same reason you are doing the Lamb. Just to prove to myself that I could do all the procesess needed to build a loco. Pete
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timb
Statesman
Posts: 512
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Post by timb on Jan 5, 2019 12:18:46 GMT
Pump body and wheels were acceptable castings, athough one of the wheels had a blow hole in the crank pin boss. I try to get the inside rim of the wheel to run truly and machine to that, always looks better in my opinion. I do the same with flywheels as well, nothing worse than to see a distinct wobble on the inside when the outside runs true. As you will see later I could get all but one to run true. The inside of the casting (rear face) that is machined first just did not match with the outside so there is a bit of a wobble - just me I guess.
Driving wheel:
Leading Wheel:
I used the Lathe 4 Jaw and toolpost method to quarter the wheels this worked fine - if they are out they are both out by the same amount.
Final assembly of the wheels, axles and suspension with the wheels running freely with no shake in the axleboxes - would it be as free with the coupling rods in place?
I turned the coupling rods from solid bar - making the ends separate then screwing to a length of round rod seemed a bit of a faf to me. Ends rounded and bushed with bronze. Nice simple stuff this with plenty of straight forward machining and assembly at the moment, I am starting to think this was a good choice to get back into building.
To be honest the trickiest thing so far had been getting the frames square. Usually the top edge of the frames can be used as a datum for the buffer beams, and the beams are angles so you have a reasonable reference face to line everything up with. The beams on this engine are lengths of 1/8" bar at either end with the top and bottom section of the frame that the beams bolt to cut away leaving a half inch wide strip at each end as a bolting face. To make it square I used a couple of DTI magnets on the surface plate to hold the frames square to one another and then stood the buffers on slips to mark the holes for drilling. The front beam was relatively straight forward but the rear is bolted through from the inside making the second set of holes difficult to mark in the extreem, having already drilled the clearence holes in the frame. I eventually got it by extending a drill with a bit of thinner welding rod, threading this through the tapped hole on the other side with one of the other bolts in place before putting the welding rod in a hand drill chuck, tricky to get all the bits to line up all the same! NOTE to anyone thinking of building this, the dimensions shown on the drawings for the bolt holes will line up with the inside edge of the angle riveted to the buffer beam. Broken drill alert at best, broken tap at worst!
Fitting the coupling rods was straightforward and I was rewarded with a running chassis with no bind and no sloppy fitting - first mile post reached.
I used 5BA bolts to temporarily hold the slips - these are now replaced with allen grub screws.
Next challenge the cylinders.
Tim
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JonL
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WWSME (Wiltshire)
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Post by JonL on Jan 5, 2019 19:18:44 GMT
What a lovely build, you certainly seem to get a nice finish!
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timb
Statesman
Posts: 512
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Post by timb on Jan 12, 2019 13:50:12 GMT
Cylinders were relatively straightforward and are pretty much the same as most others of the type. Drilling passages is a pain but I have started lining up the correct angle, eyeing it with a drill then spotting with a slot drill to get a flat land before following up with centre drill and finally twist drill to size. I have no doubt there are better ways to do this but it worked for me.
The slide valves are a pain with them having a 1/16 slot down them. The slot needs to be central and perpendicular to the port face edge, I had to get the horizontal mill attachment our for the Bridgeport (any excuse to play!!). The more difficult part to make was the valve rod which is a rectangular section in the round rod made to be a sliding fit in the valve with no appreciable end play. I tried to mill the sides but I could not hold the part to mill the second side. Making the rod longer to hold each end worked OK until facing off the short end square in the lathe which made a rather elegant if miniature cork screw out of it. I ended up filing them by hand which was a bit tedious to say the least.
The crossheads are a bit of plain milling, I made these from a block of bronze ensuring all holes were square and perpendicular to each other.
To ensure the guide bars were perpendicular to the cylinder bore and at the same spacing as the crosshead I used a jig which was a sliding fit on the piston rod. Incidentally I used graphited yarn for piston packing, I am a bit of a traditionalist and if it was good enough for Curly then its good enough for me. I managed to source the proper stuff that looks like it has been dipped in solder, a messy job but easy enough to do.
I always seemed to have a problem with glands in that I could not get the hole concentric with the thread with the inevitable binding when tightened up, this is why they are missing from the photo below. I eventually got fed up with making the same part a number of times with no joy that I had to do a bit of a time and motion study. I was following the method described by LBSC vis turn the OD and thread, mount in a bush, face, drill and ream. This did not work even if I screw cut the thread! What I did to make it work was turn the OD and thread, drill and ream, then mount in a bush and face. Probably obvious to the rest of you but I could not see that the hole must be concentric if drilled at the same setting as the thread is cut. The connecting rod blanks prior to turning are also shown in the photo.
And connecting rods after turning and rounding off the ends.
Lining up the cylinders for bolting up was relatively straight forward, ensuring the piston rod was in line with the driving axle centre with the axlebox at 1/8" above hornstay. After fitting the connecting rods and measuring the cylinder end clearance at TDC and BDC I found that either the cylinder was in the wrong place or the piston rod was 3/32 too long. I checked all measurements to the drawings two or three times, everything was OK with the cylinders in the correct position however the error was still there. I drew the lot up accurately in CAD and found that the drawing was wrong the piston rod was too long. This was a disaster, I had to strip the cylinders down, remove the nicely packed pistons and re-machine the rods. I think I learnt some new swear words that day, it was amazing that the lot did not find its way airborne across the road!
It was a couple of days after I had calmed down that I put everything back together and was rewarded with a nicely rolling chassis with moving pistons. Hopefully the following mp4 works:
Motion work next.
Tim
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JonL
Elder Statesman
WWSME (Wiltshire)
Posts: 2,907
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Post by JonL on Jan 12, 2019 17:56:28 GMT
That rolls nicely, lovely work.
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Post by David on Jan 12, 2019 22:28:42 GMT
You're doing a great job, really nice work!
Sorry to hear about the con-rods, but glad you figured it out and sorted it.
If I was to build a published design I think I'd 3D model the whole thing before I cut any metal. There are just too many bits for a designer to get every dimension correct.
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timb
Statesman
Posts: 512
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Post by timb on Jan 14, 2019 18:30:10 GMT
I forgot to mention in my last post that the cylinders that came with the auction win were also not fit for purpose. They looked like they were OK measuring the bore length, port and bolting face width etc, BUT..... I do not know for sure why I decided to measure the cylinders up - maybe the frames being wrong water pump stretcher, whatever, I decided to measure the cylinders properly. It was not necessarily odd that the cast bore was not in the correct place, it was not a long way out, nearly 1/8" in the port face direction and plenty to machine off for the correct size bore.
I plugged the hole, scribed to the port face and bolting face to give as much machining room as I dare and got it to run true in the four jaw. Using a knife tool as a reference I found that putting the bore in the correct place leaving about 1/32 to machine off each face meant the bolt holes for the cylinder covers would be on the periphery of the cylinder outside i.e. no chance of a tapped hole for the rounded edge. No matter where I put the centre I was either drilling into the bore or outside the cylinder for at least one hole. The cylinders were the wrong size, item nine and ten in the scrap box and another trip to Blackgates!
Posting this as perhaps a reminder to all to not take for granted that the correct casting has been supplied and to do some overall measuring first before machining. If I had just measured to the port and bolting faces it would have appeared OK, the issue not showing itself until drilling for the covers. To give the guy that I bought the castings from the benefit of the doubt it could be that the castings were supplied wrongly in the first place and sold on in good faith!
Talk about relieved that I did not get as far as machining the covers only to find all the time invested in the cylinders was for nought!
I would assume I am not the first to experience this issue!
Tim
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Post by gingerneer on Jan 19, 2019 20:37:45 GMT
Hi Tim
Great to see another Canterbury Lamb being worked on.
Will
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timb
Statesman
Posts: 512
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Post by timb on Jan 20, 2019 12:06:23 GMT
Getting the chassis rolling was a good milestone and spurred me on to get the thing going under its own power. The motion work is relatively straightforward being slip eccentric. Limited space and short wheelbase meant that LBSC had to come up with an unusual arrangement, I have no idea how this fits with the original but it looks quite elegant to my eye. Each of the links were made as pairs, handed as required and fitted on completion, hence I have no photos of the individual items. The most laborious part was making all the link pins which are either single or double nuts but all required threading to length at both ends, there are ten altogether.
Side elevation:
Plan view:
There is a 90 degree crank which passes through the frame, the drawings suggest this is pinned with 1/16 rod after assembly. Once pinned there would be no way to disassemble the unit should anything be amiss. I elected to fit taper pins just in case.
Setting the valve timing was fiddly, there is not much space, however I eventually got this somewhere near after a fair bit of messing about, The urge to see if it would run was strong to say the least so I made a couple of temporary "steam" (air) inlet pipes for the valve chest covers. I found a bit of tubing - well cut it from an old Cortina screen washer bottle - and realised that I had nothing small enough to connect to my compressor AAAARRRRGGGGHHH come onnnnn!! A football inflating adaptor and some 'tricians tape came to the rescue. Although the steam chest cover has no gasket, I was eventually rewarded with this:
See, as explained earlier, one wobbly inner rim - very annoying!!
Delight was tempered with annoyance however when I tried to run the chassis in reverse - no way Pedro! This had me scratching my head a bit.
I checked all the dimensions, lengths, angles, widths, everything. Whatever I looked at it boiled down to the slip pin reverse angle was too large to put the valves in the correct position. After a lot of measurement I came to the conclusion that the offset from the centre of the eccentric sheave to the top face that engages with the pin should be 3/16" and not 3/32" as indicated on the drawing. I proved this by fitting a 3/16" thick block to the reverse side of the sheave and the engine ran both directions without a problem. I have since checked everywhere I can think of to see if this is a known issue (even left a thread on here to see if anyone could help) but I have still to get this confirmed. No doubt I have made a mistake somewhere and it will probably be waiting to present itself at the most inopportune moment and cause further grief!
I have left the chassis for now and am undecided whether to remake the sheaves or solder a 3/32 brass strip on to build up the necessary distance. In the mean time I have chickened out on the boiler and will concentrate on the tender.
Tim
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Lisa
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Post by Lisa on Jan 20, 2019 12:44:45 GMT
Well done Tim! That's got to be about the most complex slip eccentric arrangement I've seen, interesting to watch though; didn't even notice the wobbly rim till I read the rest of your post.
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mbrown
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Post by mbrown on Jan 20, 2019 15:08:23 GMT
That must be one of the nicest and best finished Canterbury Lamb's I have ever seen.
Malcdolm
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jma1009
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Post by jma1009 on Jan 20, 2019 20:35:10 GMT
Hi Tim,
You have done very well! I enjoyed the clip of the chassis running.
The boiler should be a straightforward job and quite easy and not very expensive.
Cheers,
Julian
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Post by David on Jan 20, 2019 21:48:41 GMT
Good work Tim, and well done on the diagnosis!
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timb
Statesman
Posts: 512
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Post by timb on Jan 21, 2019 16:37:32 GMT
Hi Tim, You have done very well! I enjoyed the clip of the chassis running. The boiler should be a straightforward job and quite easy and not very expensive. Cheers, Julian Thanks Julian. I have most of the materials for the boiler but I would like to run this someday so I need to find a boiler inspector to lead the way so to speak. I need to build up courage!!
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timb
Statesman
Posts: 512
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Post by timb on Jan 21, 2019 16:39:31 GMT
Thanks all for your very kind words, hope the rest of it can live up to expectation.
No pressure then.......
.....well hopefully in the boiler.... eventually.
Tim
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