J39 64859 Bachmann/Dave Bradwell

Daddyman
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Re: J39 64859 Bachmann/Dave Bradwell

Postby Daddyman » Sat Apr 18, 2020 4:17 pm

Re removeable brakes on the tender, this is how I did it on Dave's J27 (I seem to remember he approved!). You'll need some points in the tender body to bolt the brake gear to, but that's just a question of soldering some straps with nuts on them on top of (or even underneath?) the tender footplate (but if on top be careful to make sure they clear the tender body).

P1350369.jpg
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PeteT
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Re: J39 64859 Bachmann/Dave Bradwell

Postby PeteT » Sat Apr 18, 2020 5:45 pm

Thanks David - looks good! I was wondering about something along those lines, though it does look like something easier to do before putting half of it in place. I'll certainly bear that in mind for the 4200 gallon version in the pipeline.

I have just sorted a pair of screw in PCB pads for pickups - so it may be achievable to anchor onto those. If I assemble it in place now and then cut below the brake shoes (middle pair could be fun) then the only major rejigging to do is the height. This I can do by working out some packing pieces before making the cuts. So the only question is whether I can access that middle pair to cut after I've built the brake gear around it.

Option B, assemble the end pairs, and then cut the middle pair out later with the brakegear out of the way. This just leaves the curve of the shoe to align properly, but that shouldn't be difficult to align with the outer ones.

Time for my walkies!

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PeteT
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Re: J39 64859 Bachmann/Dave Bradwell

Postby PeteT » Sat Apr 18, 2020 7:39 pm

Actually, a definite way forward. As the bufferbeam are part of the body assembly, I can just cut down the sides of the brake hangers with a piercing saw, and then put some replacement brackets in the end if it seems to have reduced its structural integrity.

Loco good to go for testing, 'power' through the firebox door as per the prototype!

20200418_203534.jpg

Daddyman
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Re: J39 64859 Bachmann/Dave Bradwell

Postby Daddyman » Sun Apr 19, 2020 2:29 pm

You're welcome, Pete. Looks like you have a solution now.

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PeteT
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Re: J39 64859 Bachmann/Dave Bradwell

Postby PeteT » Sun Apr 19, 2020 2:41 pm

Yes! Don't laugh too much, this is pre clean up! With pre planning it could be done with screws at the bottom of the brakeshoe brackets, but I think this is reasonably clean & unobtrusive. Following David's J27 photo I put the rear bracket around the well tank and onto the central brake cross beam, rather than onto the rear pair which would be more visible. Dave Bradwell's design of the front forks is a nice fold over etch, so this grips the cranks on the brake shaft without needing pinning, and makes a nice natural join between the two assemblies.

20200419_153334.jpg


20200419_153406.jpg


Onto cleanup, reseparate the PCB, and add the pickups.

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PeteT
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Re: J39 64859 Bachmann/Dave Bradwell

Postby PeteT » Mon Apr 20, 2020 8:27 pm

Observant readers may have noticed the error in the above photos... in that the pull rod were correctly in pairs each side of the brake shoes - but were, however, lacking the space between them for the wheel!

So a bit of tweaking to sort this out. However I'm still slightly confused, in that the front brake stretcher (part 86) looks too wide - even in P4 (the instructions note that it will need modifying for EM or 00) - for the inner of each pair to sit inboard of the wheels. The length of the part seems more aligned with the distance between brake shoes.

Sorry Dave - I see I'm not the first tonight asking for your assistance/clarity!

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Re: J39 64859 Bachmann/Dave Bradwell

Postby davebradwell » Mon Apr 20, 2020 9:46 pm

As you say, it's a busy night. It looks as if there's more plain pin showing on the front cross beam which would enable you to move the pull-rods in but check this will give you enough clearance in case you want to add a bit. I'll confess that my pull rods are bent slightly to give extra clearance. Certainly the wires at the front don't go right across, only the plank maintains the spacing of the brake blocks.

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barhamd
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Re: J39 64859 Bachmann/Dave Bradwell

Postby barhamd » Mon Apr 20, 2020 10:01 pm

But compared with this my B1 looks like amateur night!
David

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Re: J39 64859 Bachmann/Dave Bradwell

Postby davebradwell » Mon Apr 20, 2020 10:36 pm

Thinking a bit more about brakes, you can't assemble them without the wheels in place as there's no way of knowing their position. You'll struggle to get them back in without removing the stretchers across the bottom of the frames.

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PeteT
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Re: J39 64859 Bachmann/Dave Bradwell

Postby PeteT » Tue Apr 21, 2020 7:18 am

Thanks Dave, yes I had moved the pull rods as far inboard as I could - and I agree they weren't in the photos. I'll have a play and decide whether to file a bit or bend it a bit - I was just checking I hadn't got it in the wrong place, though didn't think I had as the sketches you include generally make things obvious.

The assembly will feed in place ok around the stretchers, though to do so I have shortened the PCB strips since the photo. They were originally cut to size to make use of the area available, before deciding to make them the anchor points for the brakes too. I appreciate that any issues with this bit are of my own doing! I am hoping that a reasonable estimate can be done in free air and will feed into place for tweaking, time will tell!

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PeteT
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Re: J39 64859 Bachmann/Dave Bradwell

Postby PeteT » Tue Apr 21, 2020 9:33 pm

A bit of progress (it is a school night, but is a modelling gained one as it would normally be spent with the BS4 rabble).

Further fettling can and will improve it, but the brakegear fits in and it trundles around quite happily. I may be able to make the bend in the inner pull rod less obvious - but at the same time it will eventually be black and have layout light not just camera flash to work with!

20200421_214140.jpg


20200421_214125.jpg


One thing with the loco is that it doesn't always like going around curves. I think the issue lies with the wheelsets. I have 3 potential theories, my first port of call will be Will's thread to see whether any are mentioned:
- the stub axle on the wheel is about the same length as the hornblock, so sideplay is effectively the insulated gap and I think it could be clouting the end of the inner axle (unlikely, as I'm pretty sure it isnt moving that far to start with!).
- The stub axles are ribbed, so the ribs could be catching and preventing it moving through the block
- Sideplay washers interacting with those ribs

The driven axle seems to move ok with the sideplay it has - but both others have some reluctance, and the middle one is the one I'm most interested in.

20200421_212123.jpg

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Re: J39 64859 Bachmann/Dave Bradwell

Postby davebradwell » Tue Apr 21, 2020 10:06 pm

The sideplay issue is interesting, especially as I'm about to use these wheels on my V2. I wonder if you have burrs inside the axleboxes - did you put a reamer through and then break the sharp corners at both ends of the bores using an oversize drill? If you think the step between the stub axle and axle is interfering with the back of the axlebox you might countersink the back of the axleboxes significantly to clear this.

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PeteT
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Re: J39 64859 Bachmann/Dave Bradwell

Postby PeteT » Wed Apr 22, 2020 8:40 pm

Yes, I have a set for a B1 with a similar design of chassis too... You could well be right. It is certainly down to individual blocks snagging (rather than both on an axle) so I don't see it as anything fundamental. At least these wheels don't mind being disassembled as much, but I will try and find the source and not just 'fettle & hope' before reassembly. The lack of smooth parrallel axle was something I had made a mental note of as major differences, but don't think it should stop them being perfectly reliable.

I did use a reamer, I probably used a file rather than large drill to debur so I'll make that my first port of call.

I couldn't bring myself to pull them apart tonight, but got on with the next step of my pickups. I have previously used Molex 1.25mm pitch plug and sockets - but they are still really quite chunky things to try and hide out of the way. So this time I've gone with Harwin PCB sockets. These are designed for through hole PCB mount plug in modules (eg PSUs), and they do them to suit 1mm, 0.8mm and 0.5mm pins (datasheets have tolerances for each size). The overall dimensions of the 0.8mm and 1mm versions isnt that difference (1.95mm and 2.25mm PCB holes), but the 0.5mm only requires a 1mm hole.

Good for 2A each, and 20p - I went for the H3191-01 0.5mm option for this setup. Available from Farnell, RS, Digikey and Mouser amongst other places.
https://cdn.harwin.com/pdfs/H3191.pdf If anyone feels 2A pins arent enough for them, the 1mm versions are specified for 10A.

My rear PCB plate (not yet reamed out on the underside on this photo, but 1 in place to show) will just have 1 pair to connect pickup contacts up to the motor. The front plate has 1 pair for up to the motor, and a second pair to accept the incoming pickups from the loco - so 1 pair pointing up and 1 pair down.

I might just use brass wire to plug in, but have in mind to experiment with lace making pins. While the smallest I have are 0.55mm (and sockets accept 0.46-0.51mm) so will need thinning down, I think having the head to help wrap the wire around to help mechanically hold, and easily locate for soldering, will be worth a few minutes to file them down to fit.

20200422_211513.jpg


Edited to add - the larger holes in the PCB, for comparison, are for 10BA bolts.

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PeteT
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Re: J39 64859 Bachmann/Dave Bradwell

Postby PeteT » Sat Apr 25, 2020 6:24 pm

davebradwell wrote:I wonder if you have burrs inside the axleboxes


Not a lot of modelling time today- the responsible side of me decided the conservatory was well overdue a deep clean, so as it seems to be the thing to do during lockdown I did.

However, I did make time to assess the wheelset. I think the greater issue was more the edges on the stub and centre axle sections - I went round the join with a round file to ensure neither had sharp corners and that improved matters. While it was out, and as the unseating of these wheelsets is supposed to be a strong point, I did get the hornblocks out and check those with the reamer and a bit drill bit. All back together and rolling around happily - so back to the tender...

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Re: J39 64859 Bachmann/Dave Bradwell

Postby PeteT » Tue Apr 28, 2020 6:48 pm

So far it only has pickups on 2 of the tender axles - other jobs have intervened - but this has been enough to do some initial proving. It is quite noisy, and I'm pretty confident (though without extensive use of the things to back this up!) that it is the UJ. I don't like the Ultrascale shaft as discussed on Ralph's workbench topic, but thought it would be a quick way to prove running and get the rest of the loco finished - at which point I could revisit this section and put together something less obtrusive. That plan has failed at the first step!

Re-reading Chris Pendlenton's Ivatt 4 build in MRJ (issue 175, 'A cuckoo among the Ravens'), he mentions creating cushions within the UJ from Haematite silicone gasket sealer - but I think I have a fettling stage to go through before that for fine tuning? I think there is a slight bend within the left hand (as shown below - loco end in the video) plastic section of the UJ.

20200428_181834.jpg


https://www.youtube.com/watch?v=pAgFFkJz0N8

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Re: J39 64859 Bachmann/Dave Bradwell

Postby davebradwell » Tue Apr 28, 2020 7:17 pm

One thing I see, PeteT, is that you appear to have mounted the motor rigidly on a metal brkt. If you put a plate across the well tank and just stick the motor down with double sided or sticky pads or even something like UHU you'd prevent the motor noise being transmitted to the tender. Chris's rubber pads were to remove a final bit of noise thought to be due to endplay in the shaft, lack of which would cause noise too. You're right, though, and metal couplings are a likely source of noise, especially with tight feedback motor control. It looks as if NWSL is going again although currently locked down so we might not have to wait too long for some decent plastic replacements. My J39 has a piece of 0.020" music wire as a shaft - I can't get it straight, though.

Is that a Canon motor? It shouldn't make any sound other than a whoosh at top speed with drive disconnected.

Don't let such distractions spoil your moment of triumph. The key things at this stage are does it move smoothly and does it stay on the track.

DaveB

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PeteT
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Re: J39 64859 Bachmann/Dave Bradwell

Postby PeteT » Wed Apr 29, 2020 7:40 am

Thanks Dave - I have put the motor on a pad of UHU and will try that this evening. The motor itself sat there did run quietly, but I agree that even if not the ultimate source of noise it doesn't stop it transmitting it! I'm not convinced with UHU there long term as the well tank is full of lead sheet slices - even with it spaced off it will be a constant cause for concern - but it will prove the point today.

Good point! It was good to see, and is a step in the right direction.

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Re: J39 64859 Bachmann/Dave Bradwell

Postby charleswrigley » Wed Apr 29, 2020 8:35 am

Something niggles at the back of my mind that the Ts at the end of the drive shaft should be set at 90 degrees to each other.

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steamraiser
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Re: J39 64859 Bachmann/Dave Bradwell

Postby steamraiser » Wed Apr 29, 2020 8:44 am

In the past I have seen / heard of motors being mounted in place using a good pad of bath sealent.

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Re: J39 64859 Bachmann/Dave Bradwell

Postby Dave Holt » Wed Apr 29, 2020 9:10 am

charleswrigley wrote:Something niggles at the back of my mind that the Ts at the end of the drive shaft should be set at 90 degrees to each other.

Charlie


No. The drive bars at the two end must be in line and any angle between the shafts at each end and the centre shaft should be the same but opposite. In this way any angular speed fluctuations in the centre shaft are cancelled out at the output shaft. If the drive bars are at right angles, these speed fluctuations will be doubled at the output.

Dave.

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PeteT
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Re: J39 64859 Bachmann/Dave Bradwell

Postby PeteT » Sun May 03, 2020 4:00 pm

I raided the DIY cupboard on Friday, and this looked like a suitable flexible fixing option.

20200503_164931.jpg


Much quieter! I've also upgraded to 6 wheel pickups in the tender, and got the brake gear in too. Dave B was perfectly right that my arrangement wouldn't be easy to get in and out, so the front PCB has another couple of harwin sockets for the brakegear assembly to plug into (which is still soldered to the rear PCB). So far so good.

This afternoon I've been working on my 1P ejector. The next job for the J39 will be loco pickups and brakegear. I'm planning to be novel here, and work out how to deviate from the instructions to produce a removable arrangement at the beginning - rather than half way through...

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PeteT
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Re: J39 64859 Bachmann/Dave Bradwell

Postby PeteT » Fri May 15, 2020 7:00 pm

No major leaps forward, but a few jobs ticked off. Tender detailing is taking shape, the only thing here is I'm not sure whether my filler cap loop is long enough? I've got a nice photo of Inyala running tender first while demolishing the Queensbury line, with the filler cap open, so confirms the shape but not the length as obviously. I've gone for the fancy hinge, it looks nice - and Dave suggests if there was a theme it would likely be the fancy one on rivetted tenders, so I've gone with that.

20200515_193643.jpg


Detailing at the front had jumped over the tank front overlay and coal doors, as I thought they would need opening up for the drive shaft. This they do, and I presume I should really move the whole door up, rather than just filing off the bottom side? These bits are yet to be fixed in place.

The only bit of the instructions not quite clear, but I think I have worked out, is for the front footplate. From what I can see it looks like the fall plate is on the loco, and that the footplate looks like a similar arrangement to the photo of the preserved K4 - which looks nice and elegant too. Part 158 is mentioned for the bracket, and I think 101 is the top - it looks to fit nicely. It has a suitable set of holes in it, and a suitable name in the parts list, but isnt specifically mentioned in this section of the instructions. These bits are also loose currently.

20200515_193607.jpg


Not too many steps from here before the tender is finished!

Loco wise I've ripped it all apart to start adding brakes. Likewise so far so good, nitpicking the instructions mention brake bracket 27 goes with inner flanges 30 and 31, with 30-35 are labelled with the ends ones (30 and 35) as the short pair for the front bracket, but this isn't hard to fathom out. The outer flanges don't have a short pair, but will be filed down once they are all fitted.

Here is one with the inner flange only fitted, and inner fitted and outer tacked on on the right.

20200515_193548.jpg


I have the brake shoes and beam ready to assemble around them once all the outer flanges are in place.

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Re: J39 64859 Bachmann/Dave Bradwell

Postby davebradwell » Fri May 15, 2020 7:40 pm

Pete, it's many years since I did the J39 and you might update the brake fixing. With a cunning arrangement of wire and tube spacers against the frames you can contrive grooves on the brake hanger wires (the outer flange is the bit of bracket you haven't fitted yet) into which the brake hangers with the hole extended to an open topped slot would slip. The brake beams are then linked to the dummy springs by discreet bits of wire so these hold the whole lot up and by releasing the keeper everything comes away in one go. Most popular arrangements described prevent the brake hangers being pressed in but none avoid them springing out as that described above.

The wire loop on the tender filler is much longer so it can be fitted over the dangly wire hook. If the tank overfills when picking up water then the lid can lift to release the excess and then drop down again. As you say, however, few firemen shut the lid in the first place and scoops were removed anyway.

I've just recently filed a semi circular cutout in a coal plate to clear a drive coupling and I managed to break the whole thing free so be more careful than I was.

DaveB

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PeteT
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Re: J39 64859 Bachmann/Dave Bradwell

Postby PeteT » Sat May 16, 2020 10:32 am

Thanks Dave - that sounds like a good arrangement. I was looking at mirroring the standard arrangement (tube/rod but inserted from the inside) - but was a bit concerned this may be tricky to assemble with the wheels in place, and as you say only stops sideways movement in one direction so could easily lead to moving in and dragging/shorting the wheels. I had tacked a couple of the outer flanges in place but not soldered them to the bracket so a good time to alter the arrangement.

I was wondering whether the loop went below the hook, or whether the hook rotated to release the loop - I will sort that out.

Yes I thought it looked like the coal plate may easily deform if doing it in situe, so am planning on altering it prior to fitting.

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PeteT
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Re: J39 64859 Bachmann/Dave Bradwell

Postby PeteT » Sat May 16, 2020 6:20 pm

The next step of slight confusion on my part, is with water gauges, taps & handles.

I'm not fitting a scoop, so don't need that handle. If I read the instructions correctly, the taps and valves are a choice of one side or the other - and being left hand drive makes sense to be the same as the K4. So, am I right in thinking that the below additions are all I need - & none fitted to the right?

20200516_191411.jpg


A little bit of cleaning up still to do before fitting these bits, but coming together nicely.


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