Help with a Brassmasters 4F

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Jol Wilkinson
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Re: Help with a Brassmasters 4F

Postby Jol Wilkinson » Thu May 11, 2017 2:43 pm

Russ Elliott wrote:
Jol Wilkinson wrote:The photo of the buffer bodies against the gauge would seem to indicate that the loco needs raising 1.0 - 1.5 mm, rather more than a change of wire thickness might provide.

Yes. (Hence my previous suggestion.)

So if the position of the hornblock in the guide is too low and using thicker wire won't work or will provide springing that is too stiff, then I would be inclined to replace the BM wire retainers soldered to the hornblocks with something longer (handrail knobs perhaps).

Jol, this is an underslung arrangement. Putting something longer in will make the chassis even lower!!


Ooops, it's those upside down photos that do it.

in which case, do the slots in the sided oh the hornguides allow enough vertical clearance to raise the wire sufficiently to get the ride height correc? If so, replace the chassis wire supports with some from the LRM CSB adaptor etch, which has several different types. They would be easier to solder in place than adding handrail knobs at this stage. I've added a copy of the drawing from the LRM instructions to give an idea of what they look like.

CSB adaptor dwgs A4.jpg


Still worth speaking to BM though, as they may be aware of this issue and know what is wrong or have a cunning plan to fix it.

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jsherratt
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Re: Help with a Brassmasters 4F

Postby jsherratt » Thu May 11, 2017 3:54 pm

Hello All. Will L drew my attention to this thread about this 4F kit. It is right I finished off one of these kits for a fellow member of the Crewe Group a few years ago. In fact, it is probably more like 8-9 years ago, time flies. Some of you may have seen the loco running on "Knutsford" before its retirement from the exhibition circuit.

I may not be of much assistance here as the way the loco was built, there was more "me" than Brassmasters below the footplate. I set the chassis up in traditional Sharman 3-point compensation fashion with a fixed rear axle and beam between the two front axles. The valve gear was put in place, but fixed in "dummy" fashion so it does not move or make contact with the middle axle.

The wheels used were Ultrascale and I imagine they would have the crankpin throw correct. I fitted a blanking plate (probably from a set of MJT hornblocks) to hold a top hat bearing for the rear axle. After this time, I cannot recall whether or not I packed the chassis up to get the correct ride height for the buffers or deal with any clearance problems between the rods and the footplate. The 4F is not in my possession so I cannot look at it to check exactly what I might have done. I find quite a few kits seem to need packing to get the correct buffer height, but better this way than something that rides too high!

John S

John Palmer
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Re: Help with a Brassmasters 4F

Postby John Palmer » Thu May 11, 2017 5:01 pm

What I see in Dave's photographs is a distinct set in the springing wire that may be imparting a 'nose down' bias to the engine when placed upon the track. If that is the case then any such bias is going to be magnified at the locomotive's extremity and may account in part for the front buffer centres being about 1 mm below where they should be.

As an alternative to fixing 12 new spring mountings to the frames as per Jol's suggestion, altering the mountings on the axleboxes may be worth considering. The “Brassmasters' own” photograph suggests to me that the wire is being carried nearly 1 mm distant from the bottom face of the axlebox, so it ought to be feasible to attach replacement mounts to the axleboxes that bring the springing wire closer to the underside of each box. The effect of this will be to raise the whole locomotive relative to the wheel centres.

Whilst it's straightforward enough to attach spring mountings to each mainframe prior to their assembly, I think such an exercise becomes much less attractive after such assembly has taken place. I would foresee difficulties in getting the replacement mountings secured to the inner faces of the frames correctly aligned at a constant height and position relative to each axle. I would have thought it easier to apply new spring mountings to each axlebox, halving the amount of work required.
Underhung springing.jpg

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Will L
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Re: Help with a Brassmasters 4F

Postby Will L » Thu May 11, 2017 9:49 pm

John Palmer wrote:What I see in Dave's photographs is a distinct set in the springing wire that may be imparting a 'nose down' bias to the engine when placed upon the track. If that is the case then any such bias is going to be magnified at the locomotive's extremity and may account in part for the front buffer centres being about 1 mm below where they should be.

Good point if the chassis isn't riding level it will magnify the buffer hight issue. The upside down chassis picture does seem to show the bearing blocks are at different levels and are lowest at the front). I think this also shows that the wire is nothing like as stiff as I would expect a hard steel spring wire to be and that curve up at the end looks all wrong.
As an alternative to fixing 12 new spring mountings to the frames as per Jol's suggestion, altering the mountings on the axleboxes may be worth considering. The “Brassmasters' own” photograph suggests to me that the wire is being carried nearly 1 mm distant from the bottom face of the axlebox, so it ought to be feasible to attach replacement mounts to the axleboxes that bring the springing wire closer to the underside of each box. The effect of this will be to raise the whole locomotive relative to the wheel centres.

Whilst it's straightforward enough to attach spring mountings to each mainframe prior to their assembly, I think such an exercise becomes much less attractive after such assembly has taken place. I would foresee difficulties in getting the replacement mountings secured to the inner faces of the frames correctly aligned at a constant height and position relative to each axle.

I would second that thought, reducing the distance below the axle of the wire will be a lot simpler than fitting new fulcrums on assembled chassis.

So swap the wire, and see if that is enough,
Make sure the chassis is riding level before checking buffer heights, and only then try reducing the wire to axle centre distance if that is still necessary.

I wouldn't expect too much movement out of the springs, the fulcrum points are too close to the axles for that, but actually very little movevent is required to work well on all but the most direct track.

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Serjt-Dave
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Re: Help with a Brassmasters 4F

Postby Serjt-Dave » Fri May 12, 2017 9:18 pm

Hi All. I think I will try a heavier gauge spring wire and speak to Brassmasters before I try any alteration to the original system. I find it hard to accept that I have to do anything really, it should work as supplied {providing it has been built correctly}. I accept and understand that if the fault is due to my incompetence. We will see anyway and I'll keep you posted.

Dave

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45609
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Re: Help with a Brassmasters 4F

Postby 45609 » Sun May 14, 2017 8:17 am

I've found that if built 'as designed' the loco ride height is wrong. I have been slowly resurrecting a 4F that had been built to P4 but using the EM spacers in the kit. This turned out to be advantageous in correcting the ride height but very inconvenient for making the inside valve gear fit and work. However, the latter is not the reason for this post.

In essence I have done a practical application of John Palmer's suggestion. The approach to correcting the ride height started with finding an arrangement of hornblock that brought the spring wire closer to the axle centre. I found the High Level Models (HLM) space saver design met the requirements but only when the horn guide was soldered on the outside of the EM spaced frames. The groove in the hornblock then lines up with the holes in the fulcrum tabs in the frames. The wire can then be run in the groove under the HLM hornblock tabs that have been trimmed down. The following photo shows the result from underneath.

IMG_0090.JPG


The consequence of adjusting the ride height in this way is that it compromises the appearance above the running plate. The frames, in front of the leading and between leading & middle splashers, are too low. This is where the use of EM spacers came to the rescue again. I cut off the bits of the frame on the chassis that poked above the running plate in front of the leading splashers then made replacement frame pieces to solder to the running plate assembly. The chassis now slots inside these frame pieces as shown in the photo below. The difference in height of the EM and new frame pieces can be seen. It's about 1mm.

IMG_0089.JPG


I'll add a couple more photos in a while that show the loco against a buffer height gauge.

I'm not sure if you have an easy solution Dave. Implementing a hornblock modification like mine will compromise the visual appearance of the frames above the running plate. Packing up the body will have the same result. Maybe thicker wire and ignoring the ride height is the only way.

Morgan

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45609
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Re: Help with a Brassmasters 4F

Postby 45609 » Sun May 14, 2017 6:42 pm

Here are the photos showing ride height. Without boiler things look ok. But with the boiler, that has a large bar of steel inside, I think a 0.25mm packer will still be required front and rear.

IMG_0885.JPG


IMG_0884.JPG

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jim s-w
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Re: Help with a Brassmasters 4F

Postby jim s-w » Sun May 14, 2017 8:31 pm

If it were me. I'd get some NS strip. Drill a hole in it and solder it to the spring mounts so that the wire sits under them rather than going through them. A long winded way of saying make new mounts a smidge lower.

Seems like the simplest solution to me

HTH

Jim

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Serjt-Dave
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Re: Help with a Brassmasters 4F

Postby Serjt-Dave » Tue May 16, 2017 8:11 am

Hi All, thanks for everyone's input so far. Well I spoke to Brassmasters at Expo EM last Saturday and they couldn't understand why my loco was sitting too low. Basically they suggested what everyone else has said, thicker spring wire and change the wire support on the hornblocks.

So I acquired some thicker spring wire, 0.012" and 0.014". The 0.012" had very little effect, the 0.014" did improve the height and gave better clearances between the front axle and slidebars but is still on the low side. So the next step is to replace the spring wire support on the hornblocks. Haven't decided how I'm going to do this. I'm very annoyed having to do this in the first place and looking at some of the modifications some of you have done {Morgan etc} why buy this type of kit if you then got to do some major alterations to get the thing to work or is that just me. LOL.

I'll get you posted on how I get on and if all else fails I might try adjusting it with fire and lots of it.

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Lord Colnago
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Re: Help with a Brassmasters 4F

Postby Lord Colnago » Tue May 16, 2017 10:10 am

Hi Dave,

Don't despair, it happens to us all. I am currently battling with a kit, not the same one as yourself, whose instructions clearly tell you to remove 0.75mm. from the frames where they contact the footplate casting, if you are fitting scale wheels. I am and guess how much my ride height is out by!

Persevere, you'll get there.
The second best priest

John Palmer
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Re: Help with a Brassmasters 4F

Postby John Palmer » Tue May 16, 2017 1:26 pm

Sometimes recourse to a 4lb lump hammer to visit retribution on a recalcitrant model has been difficult for me to resist, but His Lordship is right to recommend perseverance. Just think of the sense of accomplishment and satisfaction you'll feel when you get it right! Might some arrangement along the lines shown below be a solution?
Replacement spring carrier.jpg
Replacement spring carrier.jpg (24.47 KiB) Viewed 7093 times

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Serjt-Dave
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Re: Help with a Brassmasters 4F

Postby Serjt-Dave » Tue May 16, 2017 5:49 pm

M'Lord and John, thanks and of course I jest, though a 4llb lump hammer does sound tempting.

It's just so frustrating with what I call a high tech kit there seems to be a fundamental issue with it. I don't wish to bad mouth Brassmasters as they produce excellent products. I've built their Jubilee and Black 5's in the past and they were great. But this 4F will be the death of me.

Right rant out of the way now. I was thinking along the same line John with a loop soldered to the bottom of the hornblock to hold the spring wire. The only issue with that is the hornblock is only 3mm wide and the front ones are only 2mm wide, so not a lot of room to play around with. Another option is to use some Markits Conduit Holders. The centre of their hole would be about 0.5mm off the bottom of the hornblock. I'll try the loop first and if that fails the conduit holders and as Morgan said in his reply be dammed to the ride height, and if any mentions it we can always use the lump hammer.

Dave

billbedford
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Re: Help with a Brassmasters 4F

Postby billbedford » Wed May 17, 2017 7:29 am

You could try a length of tube, say 0.6-0.8m ID. File a flat on the outside and the solder the flat to the horn blocks. Once soldered file back the tube until it is only about 1mm long and centred on the hornblock. Something like this:

Hornblock ring.jpg


If you are really clever you could solder the tube to all six hornblock in one operation.
Bill Bedford
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Serjt-Dave
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Re: Help with a Brassmasters 4F

Postby Serjt-Dave » Wed May 17, 2017 8:16 am

Great minds think alike Bill. The only problem with this idea and with any other ideas with these hornblocks is that the front face has a plate soldered on it's front face. So careful thought will have to go into this.

Dave

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jim s-w
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Re: Help with a Brassmasters 4F

Postby jim s-w » Wed May 17, 2017 8:52 am

Hi Dave

Is the plate the part that provides the spring mounting? I'd have thought the easiest solution would be to unsolder it. File a mm or so off the bottom of the bearing then remount the plate and ream out the hole.

Another option would be to cut a slot in the bottom of the bearing for the spring and top it off with a bit of wire. Perhaps I'm over simplifying things though :D

HTH

Jim

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Re: Help with a Brassmasters 4F

Postby John Palmer » Wed May 17, 2017 10:39 am

So far as I can tell, the plate to which Dave refers is sandwiched between the wheel boss and the frames, performing a dual function of rubbing plate and restraint on the axlebox that prevents it from sliding inboard clear of the hornway. It is described as a faceplate on the Brassmasters' instruction sheet.

I can't see a viable alternative to solder as the means for fixing a new spring mount to an axlebox. If so, Dave will have to decide whether to carry out the operation with the axlebox on or off the axle. Doing the job with the boxes off their axles promises to be a lot easier and more controllable, but will involve removal of three wheels from their axles. Isn't that going to be needed for one wheelset in any case, because no gears have yet been fitted?

The disadvantage I see in using .6mm ID tube is that it is nearly .25mm larger in diameter than the intended .014” / .35mm springing wire. If the maximum amount by which the springing wire can be brought closer to the bottom face of the block is about 1mm then that .25mm is a significant reduction in the amount by which the locomotive could be raised relative to the axle centres.

Jim's suggestion of slotting the bottom face of the box to receive the wire gives you the best possible result in terms of raising the locomotive by the maximum amount possible, but there is little margin for error in cutting the slot before you break through into the axle bore – I estimate that margin at about .06mm on the assumption the boxes are 4mm square. Take care!

billbedford
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Re: Help with a Brassmasters 4F

Postby billbedford » Wed May 17, 2017 10:50 am

John Palmer wrote:The disadvantage I see in using .6mm ID tube is that it is nearly .25mm larger in diameter than the intended .014” / .35mm springing wire. If the maximum amount by which the springing wire can be brought closer to the bottom face of the block is about 1mm then that .25mm is a significant reduction in the amount by which the locomotive could be raised relative to the axle centres.


A quick re-calculation of the necessary tube diameter is not exactly rocket science....
Bill Bedford
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Simon_S
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Re: Help with a Brassmasters 4F

Postby Simon_S » Wed May 17, 2017 3:55 pm

It wouldn't matter if you did break into the bottom of the axle bore, it's the top half that matters.

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Russ Elliott
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Re: Help with a Brassmasters 4F

Postby Russ Elliott » Wed May 17, 2017 6:46 pm

Will L wrote:P.s. in case anybody is wondering this isn't a CSB, despite having Continuous Springy Beams. It is more closely related to individual springs per axle, but quite what the effect of using one continuous wire is I wouldn't like to say.

For the same beam strength and axle loads, a conventional CSB gives approx 2.5 times more bang for your buck, and doesn't tighten the middle axle.

4-fulcum-v-6-fulcurm-comparison.png

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45609
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Re: Help with a Brassmasters 4F

Postby 45609 » Thu May 18, 2017 9:44 am

Russ,

When you say "tighten the middle axle" I presume you mean the effective spring stiffness to be slightly greater than the two outer axles? This would lead to a tendency for the chassis to see-saw on the middle axle but as your diagram does not have any deflection scaling it is impossible to know if you would consider it significant.

I think Jim's idea of soldering new spring tabs to correct the ride height issue seems to be the simplest solution. I wish I'd thought of it. Irrespective of where Dave (or anyone else) might be in attempting to build the kit with springing this idea would involve minimum modification of the parts provided. Accuracy in making 12 new and identical spring tabs might present a problem from a hand fabrication point of view. It is crying out for a small commissioned etch. Also there would be a way to soften the centre axle stiffness by adopting the approach in the following diagram. The only downside I can foresee is the spring wire will sit below the line of the loco frame. I'd be inclined to fit the springs as 6 individual wires with the ends bent over 90 degree rather than 2 continuous wires. I think we all believe it is not really a good CSB concept anyway.

4F spring tabs.jpg


Morgan

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Russ Elliott
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Re: Help with a Brassmasters 4F

Postby Russ Elliott » Thu May 18, 2017 10:22 am

45609 wrote:When you say "tighten the middle axle" I presume you mean the effective spring stiffness to be slightly greater than the two outer axles?

Yes.

This would lead to a tendency for the chassis to see-saw on the middle axle but as your diagram does not have any deflection scaling it is impossible to know if you would consider it significant.

The difference in this particular case was approx 20%. Probably not significant, but it's a general precept in CSBs that middle axles should not be stronger than outer ones. I did have a 'finger prod' of a Brassmasters 4F when they were first produced, and I recall feeling the middle axle was a bit too stiff. A slight lengthening (by 2mm) of the span over the middle axle would have solved the problem.

The main message of my diagram is that, wire for wire, a conventional 4-fulcrum CSB gives a far greater deflection than the 6-fulcrum approach.

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Simon_S
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Re: Help with a Brassmasters 4F

Postby Simon_S » Thu May 18, 2017 2:52 pm

:idea: Use separate springs for each axle with lighter springs for the centre axle.

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Serjt-Dave
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Re: Help with a Brassmasters 4F

Postby Serjt-Dave » Mon May 29, 2017 8:06 pm

Hi All. Sorry for the lack of input with this, been having to deal with a death in the family.

I was going to go for lowering the spring wire supports either side of the hornblock guides and purchased the London Road Model system. But looking at the replacement wire supports some would interfere with the motion support bracket and as this would lower the entire hornblock leaving a empty space behind the wheel. So I opted for reducing the height of the wire from the bottom of the hornblock.

Before cutting a trench into the bottom of the hornblock I cut a appropriate piece of tube filed it in half and soldered it to the bottom of the hornblock. This has gained me about another 0.75mm. I've only done one hornblock so far so won't know how much the overall ride height is until I've done the other five, but signs are looking good. Sorry that some of the images are a bit blurry {not sure if it's my eyes or my camera}.

Will keep you posted once I've done the whole chassis.
a hornblock 1.jpg
a hornblock 2.jpg
a hornblock 3.jpg

John Palmer
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Re: Help with a Brassmasters 4F

Postby John Palmer » Fri Jun 02, 2017 2:37 pm

Looking very promising... Stiffer springing wire may now suffice to bring the upperworks to the correct ride height, but even if that's not the case you may well find a need for nothing more than .010" to .020" packing to get the buffers up to the right level.

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Serjt-Dave
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Re: Help with a Brassmasters 4F

Postby Serjt-Dave » Fri Jun 02, 2017 4:03 pm

Hi John. Have now done all the hornblocks and resembled it. It runs quite nice {just by letting free roll} and the rods doesn't bang underneath the footplate. The ride height is almost there being about less than 0.5mm too low. To be honest I could live with that but will see how it is once the build is complete and weighted correctly. If it becomes too low again I might have to re-tweak the hornblocks again. I will raise the body slightly on the chassis anyway.

I don't want to waste anymore time on this kit, fed up to the back teeth with it so I now want to crack on and finish the bloody thing. I've got a second one to make, which I hope will be easier as I now know it's pit falls.

I'll post some images of the loco next to a height gauge so you can see for yourselves.

Dave


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