Bachmann B1

DougN
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Re: Bachmann B1

Postby DougN » Mon Apr 27, 2020 2:03 am

Very nice Dave. I found that the B1 needed a massive amount of weight to run when I built mine. I am almost at the point where I have to start revising things as my techniques and builds have improved some what... My painting on the other hand is massively improved.

I think you are right I need to do the same tests with my V2's to see that every thing is running before more fettling on the valve gear. I have made the springs to the underside similar to the build in MRJ 66/67 So I can still get "at" everything.

Weekend before last no modelling got done, last weekend I was fiddling with a high level Nielsen 12"... which still needs more fiddling.

hey ho!

Doug
Doug
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barhamd
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Re: Bachmann B1 - need help with pickups

Postby barhamd » Fri May 01, 2020 11:26 pm

I made some pickups following the suggested diagram in the instructions. I connected these to the motor and was able to run the locomotive up and down pretty well. Flushed with success I moved on to making the brakes and then found that they fouled where I had just made the pickups. I felt a bit dumb!

IMG_7966a.jpg


I then went back and had another go and I'm afraid I really not happy with any of my attempts. In the past I have pretty much always used top flange wiping pickups and never really had any luck with trying to pickup off the bottom of the wheel. I'm slightly embarrassed by the next picture but I'm hoping folks can point out where I'm going wrong.

IMG_7967a.jpg


From left to right we have:-
a straight wire from the opposing side of the chassis (to give a bit more length) just rubbing on the side of the flange, This seems to pick up ok but I'm not that enamored with the visible point of wire.
a '3-twist' spring with a short length that kicks back and rubs on the back of the tread. this seems to fall off whenever the wheel moves slightly, particularly an issue with the little bit of side play on the centre axle.
a '3-twist' spring with a longer kick back, this seems to have an awful lot of vertical movement as the wheel rotates and can get very close to shoring out on the dummy leaf springs.

help?

David

Philip Hall
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Re: Bachmann B1

Postby Philip Hall » Sat May 02, 2020 12:36 am

My preference is always to have a thin spring wire with two or maybe three coils in it, as per your four right hand pickups, but bearing on the edge of the flange as per your left hand two. I always use 0.3mm hard brass wire mostly because it’s a little thinner than the thinnest phosphor bronze you can usually get and I find it easier to form.

Sometimes arranging these coiled pickups can be easier if a couple of longitudinal bus bars (0.7mm or 0.8mm brass wire) are put in along the chassis and the pickups soldered to these.

My experience with these things is that I can never usually get a light enough but firm enough pressure with a straight wire alone. I can get away with it on a tender chassis for the two outer axles (like on the LSWR D15 I’m converting at the moment), but never have any luck on a driven chassis. In particular, any wheel that goes up and down needs absolute freedom to do so, and a pickup bearing on the edge of the flange at right angles seems to have a very light pressure and minimal drag.


A pickup bearing on the back of a flange also gets dirty and cleaning that area is a pain because you have to do it with the engine upside down and the wheels rotating. The great thing about flange edge collectors is that for most cleaning I can just spread a piece of tissue on the track, dowse it with cleaning fluid and run one wheelset at a time on the tissue. All the muck comes off the tyre surface and the edge of the flange in one go. If I ever have to clean with (say) a wire rotary brush the same applies, both the tyre surface and flange edge get cleaned in one go. For the same reason I never use a wiper bearing on the tyre surface - you have to take the body off to clean them - again the proverbial pain.

I’m not sure how much difference this makes, but I also always polish the Alan Gibson tyres with a rubber abrasive wheel in a mini drill. Certainly the surface finish is improved. As mentioned above, I also have pickup on at least four wheels of a tender. The difference this can make to the steadiness of running can be quite marked, possibly because as these things inevitably get out of adjustment there is plenty of back up along each side of the engine...

Philip

Philip Hall
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Re: Bachmann B1

Postby Philip Hall » Sat May 02, 2020 9:34 am

David,

I have just noticed that you felt unhappy with the appearance of a ‘flange edge’ pickup? I have never really noticed such a tiny wire on end down amongst the brakes and sanders. Guy Williams and John Hayes used this type and they’re very difficult to see...

Philip

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Will L
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Re: Bachmann B1

Postby Will L » Sat May 02, 2020 9:49 am

David
Some very sound advice from Philip there :thumb.
I use very similar methods with a few quirks of my own. I do use PB wire, which harder to form than brass but retains its shape better, and there is a little twist of my own which I do to aid adjustablity. I have posted on how I do this before and you may find these two post useful.
viewtopic.php?p=21164#p21164
This goes through making them in some detail. It is applied to some tender pickups applied to the tread at the wheel tops, but the same construction basic principles apply. As you have already noted, not easily applicable to a B1
viewtopic.php?p=21164#p21189
At the end of this one you will find the same basic ideas applied to under hung flange edge pickups which will suit the B1.

Edited to get rid of a thsi
Last edited by Will L on Sat May 02, 2020 11:39 am, edited 1 time in total.

davebradwell
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Re: Bachmann B1

Postby davebradwell » Sat May 02, 2020 10:51 am

This all gets a hmmm as I've been thinking we don't really know what's going on with pick-us. I have always used the straight wire type described in the instructions satisfactorily. The brakes usually go on one side of the wheel and the pick-ups on the other and the end of the wire is difficult to see when all painted/covered in oil/muck/gunge especially when cut short. A colleague has changed to the coil type so that works for him - if the wire is about the same length as the first type then vertical movement should be the same.....for the same pressure. Both types keep to the flange edge to obtain max pressure due to minimum contact area.

That's all good evidence that what you have is sound and nothing posted appears to disagree. I do find, however, that new locos can be a bit reluctant so usually end up putting a tiny amount of oil on the pickups - I find the same with new track - which helps until things bed down themselves. Freshly machined surfaces are very active so I suspect this affects the contact but I'm guessing here. Don't forget basic lubrication of the loco as I've known a dry bearing seize under rather rigorous testing.

During a recent discussion of pick-ups on this forum the use of gold emerged but was thrown out by someone without a reason being given. The only disadvantage of gold wire I could find online is that it will wear more quickly than other materials.

I now tie the brakes to the dummy spring unit with a few discreet pieces of thin wire to improve their stability. Front brakes are very close to the bogie wheels and any slight distortion during handling can cause shorts. Brakes, pick-ups and dummy spring keeps then all come off as one piece.

If the loco needs a lot of weight this might suggest that there is too much weight on the bogie so just bend the bogie springs a little in the centre - the same both sides of course. One day I'll find a way to add an adjustment here. Certainly my B1s are very heavy but have to pull 10 coaches up 1 in 100 and round bends. Useful weight can be added under the motor but don't let it interfere with the ability to drop the wheels out.

DaveB

Dave Holt
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Re: Bachmann B1

Postby Dave Holt » Sat May 02, 2020 12:53 pm

David,
You've already had good advice but I'll add my thoughts, if you don't mind.
Like Philip, I use 0.33 or 0.31 mm hard brass wire. Where possible, I have the pick-up bearing on the back of the wheel flange, where it is hidden from normal view by the brake blocks. In the pick-ups on the front two axles on your B1, I would say that the coils are in the wrong place and are not contributing to the flexibility of the wire. They would work if the pick-up was bearing on the wheel rim, as per the rear axle. To be effective for pick-ups bearing on the back of the flange, the coils need to be located in the (almost) fore/aft run of wire, as per the photo below. By careful adjustment of the bearing force between wheel and pick-up, you can minimise up and down movement whilst still allowing for side play in the wheel-sets.
Crab_003.JPG

Crab_002.JPG

Hope that helps.
Best wishes with the build, which looks to be coming along really nicely. I'll be following progress keenly as I have one of Dave's chassis to do at some time.
Dave.

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PeteT
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Re: Bachmann B1

Postby PeteT » Sat May 02, 2020 7:01 pm

Philip Hall wrote:I always use 0.3mm hard brass wire mostly because it’s a little thinner than the thinnest phosphor bronze you can usually get and I find it easier to form.


I use 33swg/10 thou/0.254mm phosphor bronze wire, from Eileen's.

I have generally used coils but not entirely convinced the way I have rigged them has added much value, so am trying simpler L shapes on the J39 and will see how that gets on.

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barhamd
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Re: Bachmann B1

Postby barhamd » Sat May 02, 2020 11:06 pm

Thanks for the suggestions everybody.

I've persevered with the coils and made them into flange wipers. They seem to be working better so we'll see how they go.
IMG_7974a.jpg


Several hours this evening making the first slide bar, quite a challenge but ok I think in the end. There was a lot of cusp to remove as the etcher had been rather frugal with the acid. Bending the joggle in the lower slide bar guides was the hardest bit. The two parts at this stage are just pinned together.

IMG_7970a.jpg


When Dave Bradwell says the clearance is tight he is not kidding and I'm going to have to do a proper job on the front crank pin before too long. The coupling rod just clears the bottom of the slide bars, but not the currently extended bits of .45mm wire which pin it together. Once these get files down to be bolt ends I think I'll be ok.

IMG_7972a.jpg


IMG_7973a.jpg


I'm quite pleased that when you put the appropriate 1.25mm rod through the cylinder the cross head casting moves pretty smoothly in the slide bars.

Thanks for the encouragement and please shout out when I'm going wrong!

David

DougN
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Re: Bachmann B1

Postby DougN » Sat May 02, 2020 11:24 pm

Just a word of thanks from me on the pickups, it's one area I find very frustrating, this is encouraging me to go and have another go! :thumb
Doug
Still not doing enough modelling

davebradwell
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Re: Bachmann B1

Postby davebradwell » Sun May 03, 2020 9:13 am

Well at least you're rolling again. There were only subtle differences between the proposed pick-up styles so you're in the right area and can make subtle tweaks to suit yourself. It's worth checking with an eyeglass that they touch the wheels at all spring positions. Also place loco on flat surface and lift each wheel in turn with screwdriver blade to test suspension working freely.

It seems you've won with the cylinders - don't forget the prototypical extra clearance for the conn rod at the rear ends of the lower bars. Give the conn rod a good filing so clearance doesn't need to be excessive. If you're very careful you should be able to get all the motion together without having to risk soldering any moving joints. Don't forget to keep checking with the diagrams that there's enough swing at joints.

Didn't you like my enamelled wire for connecting pick-ups? It's self fluxing, too, so no need to strip.

I'm building a Finney V2 - inspired by DougN - and compared to that you've loads of clearance behind the slidebars. Keep at it, you're nearly there.

DaveB

DougN
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Re: Bachmann B1

Postby DougN » Sun May 03, 2020 11:29 am

Well Dave the V2's were frustrating me so I have moved away for a bit, a high level Nielsen 12" and a LRM D17 have been having some time spent on them. The D17 was in for pickups to be fixed.., so it can now run. And the Neilson was fettling to get it to run, a bit of paint, I am not far of having it running also. I'll be back to the V2's soon! :shock:
Doug
Still not doing enough modelling

Julian Roberts
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Re: Bachmann B1

Postby Julian Roberts » Sun May 03, 2020 1:12 pm

It's always such an irony - we go to great lengths to make the brakes as close as possible to the wheels yet not touching at any point of the suspension/sideplay travel, then to even greater lengths to get pickups on that touch at every place the wheel might go yet are invisible and do their job. I always wonder if I could devise a way of making the brakes be the pickups...

Philip Hall
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Re: Bachmann B1

Postby Philip Hall » Sun May 03, 2020 2:39 pm

I’ve done pickups that are hung off the brake gear, by making the cross shafts of thin PCB, suitably gapped, and soldering the longitudinal rodding to that. The pickups in turn were soldered to the rodding. This worked best when there were two longitudinal rods, one each side corresponding to the wheels. It gets a bit more complicated when there is only the one central rod, like on the B1, but I have done this by having two rods close together - you can’t tell it’s not one from normal viewpoints.

It’s quite a fiddle and can be a bit more visible so I have only used this method when there is no other way to arrange the flange edge wipers.

Philip

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barhamd
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Re: Bachmann B1 advice on minimum thickness crankpin?

Postby barhamd » Sun May 03, 2020 4:04 pm

So I want to have a crank pin nut recessed into the rod so that there is the maximum clearance.

I only have Gibson crank pin parts available and these have a bush, the running section of which is which is O/D 1.5mm, the coupling rod is currently drilled for this. The Gibson crank pin nuts are O/D 1.8mm on their smaller side. Both are O/D 2.5mm on the larger sections.

The coupling rod has a half etched recess into which the 2.5mm section of either will fit.

I can see a couple of options.

a) Open the coupling rod hole out to 1.8mm for its whole depth and use a crankpin nut behind the wheel as a bush and reversed (i.e. small face to small face) sitting in the recess at the front.

b) Try to open up the coupling rod to 1.8mm part way from the front and use the 1.5mm crank pin bush against the wheel and a reversed 1.8mm O/D nut at the front.

It seems the former is easier (drill through something rather than trying to drill half way) but this seems like a 'no plan B' option.

Any views?

David

davebradwell
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Re: Bachmann B1

Postby davebradwell » Sun May 03, 2020 6:21 pm

Neither of your options sounds very exciting and are liable to unwind in service. I don't like using locking compounds as they can stray and give trouble. First check wheels are truly flat across front - you've already said you've filed them down. Remember you don't have a clearance problem yet so no need to go overboard .......just now. A bit of care should win through.

The instructions say that the nut doesn't need to be completely flush with coupling rod so let's stick with that. The conn rod is the greatest hazard and that is a couple of thicknesses away at the big end. The coupling rod boss just sneaks behind the slidebar end.

If you file down the outside of the flange on the existing front crankpin bush you will move your coupling rod slightly closer to the wheel at the front to gain a little space. Cut down length of existing bush to allow slight but visible endfloat of rod and fit crankpin nut normally - much of it will be in the recess. File off most of protruding reduced piece to get clearance. If you put a couple of nicks in the edge of the nut you will be able to tighten it with something akin to a Romford screwdriver filed out of silver steel and held in a pin-vice. It's worth checking there is a chamfer on corner of flat back face of nut to clear etched cusp in recess.

If crankpin clouts the slidebar check it's down to 2.5 wide as the sheet was under-etched? You might sneak off a bit more at the back at the end. Are slidebars fully into cylinder? The etch cusp at front of lower bar may be spacing it out but check clearance of crosshead at ends of slidebars. Are they parallel to frames or do they drift towards them? I'll go and check my loco as I don't recall it being a difficult bit of design and I suspect crankpin doesn't reach slidebar - it doesn't on mk1 B1.

There's more can be done if it keeps clouting conn rod but one step at a time.

DaveB

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barhamd
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Re: Bachmann B1

Postby barhamd » Sun May 03, 2020 10:23 pm

I've worked on the other side slidebar and now have two that fit and slide well. I also replaced the plastic wire insulation with a standard crank pin nut, which as Dave says, recesses into the coupling rod once the bush is filed down a bit. I've also taken a gnats off the boss of the coupling rod as I there was still cusp on the end which had filled with solder making it, I suspect, slightly over size.

The coupling rods no clear the end of both slide bars (just) as long as the front springs aren't too compressed.

I am a bit unclear of the intended relationship between the coupling rod bosses and the slide bar ends, are they meant to clear it just be being 'inside' the slide bars width ways or by being back from the slide bars along the locomotive or both?

Is there a critical dimension between the end of the slide bar and the back of the cylinder? As suggested my issue might be that the cusps mean the slidebar is actually sitting too far back by a few thou. As it is the other end of the slight bar just protrudes though the slot in the front of the cylinder.

These photos may demonstrater if/where I'm going wrong.

IMG_7975a.jpg


IMG_7976a.jpg


I think I'll have a go at making up the connecting rods anyway, they can help me check whether I can get the clearance in that direction to work.

David

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Horsetan
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Re: Bachmann B1

Postby Horsetan » Sun May 03, 2020 11:49 pm

Are you able to file a mitre on the inner sidebar end to create a bit more room, or is it too late for that now?
That would be an ecumenical matter.

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barhamd
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Re: Bachmann B1

Postby barhamd » Sun May 03, 2020 11:59 pm

Yes, absolutely nothing is fastened together at the moment.

The question is whether that is necessary, whether there is a better way and whether that is enough.

David

davebradwell
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Re: Bachmann B1

Postby davebradwell » Mon May 04, 2020 8:21 am

There looks to be way too much interference there. In desperation I tried some numbers:

Cyl centres are 6ft 7 1/2in less 7 1/2" wide slidebar should give you 24 between.

2mm wide wheels, 17.7 b-b plus 0.3 crankpin flange each side plus 1.8 for 2 rods gives 24.1, hence my suggestion to thin the flanges of the crankpin bushes. My coupling rod slips behind the slidebar so it's worth just checking the dimensions and see what's strayed from the drg.

The slidebar is a little longer than scale because the wheels have a 14" throw (the original Alan Gibson was an LMS man).

Try a rule over the wheel face as there's a hint of the centre protruding - it should be flush with the steel tyre.

You're not far away so don't do anything drastic. The odd chamfer here and there will help it all run smoothly once the basic dimensions are sorted.

DaveB

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barhamd
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Re: Bachmann B1

Postby barhamd » Mon May 04, 2020 1:42 pm

I think I'm getting there but you will have a few days peace on this topic as my soldering iron has just packed up. Order placed with Eileen for a replacement.

Thanks to Dave Bradwell for all his encouragement.

David

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Flymo748
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Re: Bachmann B1

Postby Flymo748 » Wed May 06, 2020 8:36 pm

barhamd wrote:I think I'm getting there but you will have a few days peace on this topic as my soldering iron has just packed up. Order placed with Eileen for a replacement.

David


What do you mean? Surely every Society member has a RASI (Redundant Array of Soldering irons)?

I acquired my spare when the element blew in my Antex. Ordered a replacement element. Shades of "how does the snowplough driver get to the snowplough" when I realised i had to solder it in place.

Cue a follow up order for a second iron to do the job...

Cheers
Flymo
Beware of Trains - occasional modelling in progress!
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barhamd
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Re: Bachmann B1

Postby barhamd » Wed May 06, 2020 10:09 pm

Well to be honest I do have a couple of other irons in my RASI but a 40W Weller with a bit the size spade isn't really suitable for this job!
David

Bellerophon
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Re: Bachmann B1

Postby Bellerophon » Mon May 11, 2020 5:39 pm

Thank you David (and Dave) for this thread. It has given me the push I needed to get going again with my B1. Next step is the horn blocks and guides. The bit I've been putting off, so it's time to pull my finger out. 61208 was built by a friend which I'm using for reference.

Thanks
Howard
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barhamd
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Re: Bachmann B1

Postby barhamd » Wed May 13, 2020 11:18 pm

So my replacement iron arrived from Eileen, I purchased the slightly more expensive version which has silicone lead and I must admit I'm rather impressed with the difference from the cheaper PVC cable. The additional flexibility means there is considerably less drag on the iron.

So, on with the build....

I made up the connecting rod and, after only a reasonable amount of fiddling, managed to get the little end to pivot nicely in the cross head casting. I took a little bit more meat off the front crank pin nuts and managed to get the necessary clearance to make the wheels go around and the cross heads move in and out! very satisfying.

IMG_7986a.jpg


There are a few more things to do before joining this lot together finally. I've cleaned out the piston valve castings and drilled them per the diagram.

At this point I've got a bit lost by the instructions, but I'm sure Dave Bradwell will point me in the right direction.

Piston valve castings. Clear any flash off inside guides to get a smooth surface. Drill holes in rear ones rear ones for drain cock linkage to pass through.
ok so far.....
Try links 59 through from below - the top end is straighter.
I can't find a part 59 on the parts list in the instructions (1-35 on the NS etch and 101-134 on the brass)
I can find the brass casting which I think looks like drain cocks but I thought this fitted onto the bottom of the cylinder?
There is a diagram on the second sheet showing the drain cock linkage support (part 108) which appears to show something running through the hole in the piston valve casting but I can't see what it is supposed to be.

Ease the corner inside to allow it to be fitted
Not quite clear exactly what this means, I think 'it' refers to the rear piston valve casting, but it might be something else?
Front casting has flat underneath to clear cylinder
That make sense.

In the absence of a nice detailed photograph I'm at a bit of a loss whether to use the earlier (part 21) or later (part 21a) drop link, I'm presuming the later given my late-50s timescale. There is a nice detailed diagram on the sheet but it isn't quite clear to me what the little half-etch section on the two centre parts of 21a is for or exactly where the 'tiny overlays situation nearby on the fret for 21 go. (are they only for the earlier version).

Still, it rolls and bits go in and out, so I'm happy!

David


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