Mol's MSC Hudswell Clarke 204hp Diesel

[Regularity]

3 hours ago, Mol_PMB said:

it's tricky to implement on a short-wheelbase 0-6-0 with jackshaft drive with the motor driving on the middle axle

I disagree. I did this for a Dreary 204hp loco in S, using a centre pivot for the leading axle and twin beams for the other two drivers. It is only a problem if you insist on having a fixed axle.

 

Attached are pictures of my DX goods in S, but the principle is the same. In fact, on the "204" it was easier as the jackshaft drive axle provided a useful reference point for the "horn blocks".

(Although I cut the frames, Trevor Nunn did the rest of the work on this one.)

 

 

[Mol_PMB]

12 minutes ago, Regularity said:

I disagree. I did this for a Dreary 204hp loco in S, using a centre pivot for the leading axle and twin beams for the other two drivers. It is only a problem if you insist on having a fixed axle.

 

Attached are pictures of my DX goods in S, but the principle is the same. In fact, on the "204" it was easier as the jackshaft drive axle provided a useful reference point for the "horn blocks".

(Although I cut the frames, Trevor Nunn did the rest of the work on this one.)

 

Many thanks - that's good inspiration and interesting to see how you've done a 3-point suspension with the rocking beams.

I suppose a fixed axle isn't strictly necessary as long as there is some form of torque reaction link for the motor/gearbox. How did you achieve that?

 

Is there a particular reason for using hornblocks rather than just mounting the axle bearings in a more substantial pivoting beam?

 

I think I'm a bit more daunted by the knuckle joints in the coupling rods but perhaps I'm over-thinking it?

 

 

 

 

 

[Regularity]

40 minutes ago, Mol_PMB said:

Many thanks - that's good inspiration and interesting to see how you've done a 3-point suspension with the rocking beams.

I suppose a fixed axle isn't strictly necessary as long as there is some form of torque reaction link for the motor/gearbox. How did you achieve that?

 

Is there a particular reason for using hornblocks rather than just mounting the axle bearings in a more substantial pivoting beam?

 

I think I'm a bit more daunted by the knuckle joints in the coupling rods but perhaps I'm over-thinking it?

In the case of the DX, the motor is 2mm smaller than the inside of the boiler, and is restrained by a couple of pieces of elastic band. The gearbox (Highlevel) drops down inside the firebox, then uses an "extender" to reach the rear axle.

 

In the case of the Drewry (which I stupidly sold on more than a few years ago, but would not be able to access right now anyway), the central axle was driven via a DJH GB-2 50:1 gearbox, with a Mashima circular can motor and a 20mm diameter by 10mm long solid flywheel (anyone one thinks flywheels of this size should be dished needs to re-learn their physics: a hollow flywheel has more inertia than a solid one only if they have the same total mass; removing brass reduces the mass, it doesn't increase it in the rim). IIRC, the torque reactor was an open D shape piece of wire, soldered at each end to a frame cross member, and passing up and over the motor.

 

Separate horn blocks mean I can remove all wheels from the frames without disturbing the quartering, making maintenance and painting so much easier. A piece of tube either side at the bottom of the horn blocks can have a piece of wire passed through both to retain the bearing.

 

You have two choices with the knuckle joint: use that as a pivot - and the tube you have inserted suggests that could be a possibility - with in your case, the section with the knuckle protruding forming the outside layers of a sandwich (the bread), and then the other piece forming the middle (meat). Or you can just let the "knuckle" be cosmetic, and use the crankpin as the pivot, which is what most modellers do: again you can arrange for the laminates to interlock. Because of scaling factors, our models don't experience forces in the same manner as the prototype, so this is perfectly sound. The jack shaft drive is usually arranged this way, anyway!

 

In either case, I would make a small jig consisting of a piece of wood with wire pins spaced to suit the wheelbase, using a central section of the coupling rods for spacing, and assemble in pieces on that - a drop of oil on the pins keeps them from becoming soldered.

 

----------+-- ---------------- Layer 1 - laminate for first part of rod, for crankpin or rivet (+), gap (- -), then second section 

-------- -|------------------- Layer 2 - laminate for first part of rod, hole (|) for crankpin or rivet, tube then second section 

----------+-- ---------------- Layer 3 - laminate for first part of rod, crankpin or rivet (+), gap (- -), then second section 

 

I only had two layers to work with, and there were no problems.

Edited February 4, 2021 by Regularity
Ask if you have any more questions.

[Mol_PMB]

7 minutes ago, Regularity said:

In the case of the DX, the motor is 2mm smaller than the inside of the boiler, and is restrained by a couple of pieces of elastic band. The gearbox (Highlevel) drops down inside the firebox, then uses an "extender" to reach the rear axle.

 

In the case of the Drewry (which I stupidly sold on more than a few years ago, but would not be able to access right now anyway), the central axle was driven via a DJH GB-2 50:1 gearbox, with a Mashima circular can motor and a 20mm diameter by 10mm long solid flywheel (anyone one thinks flywheels of this size should be dished needs to re-learn their physics: a hollow flywheel has more inertia than a solid one only if they have the same total mass; removing brass reduces the mass, it doesn't increase it in the rim). IIRC, the torque reactor was an open D shape piece of wire, soldered at each end to a frame cross member, and passing up and over the motor.

 

Separate horn blocks mean I can remove all wheels from the frames without disturbing the quartering, making maintenance and painting so much easier. A piece of tube either side at the bottom of the horn blocks can have a piece of wire passed through both to retain the bearing.

 

You have two choices with the knuckle joint: use that as a pivot - and the tube you have inserted suggests that could be a possibility - with in your case, the section with the knuckle protruding forming the outside layers of a sandwich (the bread), and then the other piece forming the middle (meat). Or you can just let the "knuckle" be cosmetic, and use the crankpin as the pivot, which is what most modellers do: again you can arrange for the laminates to interlock. Because of scaling factors, our models don't experience forces in the same manner as the prototype, so this is perfectly sound. The jack shaft drive is usually arranged this way, anyway!

 

In either case, I would make a small jig consisting of a piece of wood with wire pins spaced to suit the wheelbase, using a central section of the coupling rods for spacing, and assemble in pieces on that - a drop of oil on the pins keeps them from becoming soldered.

 

----------+-- ---------------- Layer 1 - laminate for first part of rod, for crankpin or rivet (+), gap (- -), then second section 

-------- -|------------------- Layer 2 - laminate for first part of rod, hole (|) for crankpin or rivet, tube then second section 

----------+-- ---------------- Layer 3 - laminate for first part of rod, crankpin or rivet (+), gap (- -), then second section 

 

I only had two layers to work with, and there were no problems.

Wonderful, many thanks for the advice - some very neat hints and tips there for the torque reaction, the hornblocks and the rods.

I'm thinking of milling new rods from solid but I can certainly use the same principles.

[Mol_PMB]

This afternoon I have soldered the bufferbeams to the footplate, and also soldered on some 1mm square brass to the edges of the footplate to make it appear the correct depth.

I bolted the body parts back on for some photos to show the current state of the model.

 

Next task is to design the new chassis and then build it. I still need to mull over the concepts a bit more and play with the dimensions in CAD.

If I decide to go with the cosmetic sideframes and a separate functional chassis inside then that can proceed in parallel.

 

[jdb82]

I'm not normally one for a diesel, but your model is superb! Also rather envious that your photos make it appear as though you have go some sun........something I've not seen up here for quite a while!

 

[Mol_PMB]

14 minutes ago, jdb82 said:

I'm not normally one for a diesel, but your model is superb! Also rather envious that your photos make it appear as though you have go some sun........something I've not seen up here for quite a while!

 

Many thanks! I thought I'd take advantage of some sun to take the photos outside.

[Sweet pea]

Looks amazing in the natural light.

[Mol_PMB]

I've had a go at the unusual coupling. I used parts of a lost-wax cast screw coupling, some brass wire, a brass rivet and a tiny offcut of nickel silver shim. I think I've about captured it.

Now I need to make another one, and then see if I can find a chemical that will blacken both brass and solder...

 

[Sweet pea]

Excellent work modelling the coupling.

[Barclay]

21 hours ago, Mol_PMB said:

 

Is there a particular reason for using hornblocks rather than just mounting the axle bearings in a more substantial pivoting beam?

 

Hornblocks have a dished groove which allows them to tilt out of square with the frame and therefore not pinch the axle in the way that a bearing that can only move straight up and down would. This is the theory I believe but plenty of people use the other system and presumably have no issues so perhaps it is more in the line of pure theory rather than practice ?

[Regularity]

My grooves aren't dished! 

This is only necessary if you insist on running locos on really, really, bad track.

In practice, I am with Guy Williams on the amount of movement required: more than ± half a millimetre and you need to look at the quality of your track laying.

[Barclay]

2 minutes ago, Regularity said:

you need to look at the quality of your track laying.

I prefer not to look at mine !!

[Mol_PMB]

14 minutes ago, Barclay said:

I prefer not to look at mine !!

I’m not far off starting tracklaying. The loco will be used to test the track and vice versa! I don’t plan to have terrible track...

 

Somewhere I have an old Bachmann Brass 08, I might see if I can resurrect that for track testing. 

 

I do want to ensure that the loco runs reliably and smoothly at low speed, as this will be a shunting layout and the hand of god should be strictly limited to coupling activities. Also it will be sound fitted and that can sound terrible when contact is lost. 

 

I’m still mulling over design options for the chassis. I think I am going to have some degree of resilience, probably with the bearings soldered into equalising beams for simplicity. 

 

I also think I’m going to go with the concept of cosmetic frames with all the detail, and a separate sub-assembly of the working bits that fits between, with the axles and wheels poking through slots in the cosmetic frames. 

 

[5050]

Try Hobby Holidays for a blackener that works on several materials, brass and solder included.

[Regularity]

You can add stay alive capacitors, etc, to keep the DCC sound and indeed control going: good for the occasional interruption, but potentially something which is disguising underlying problems.

 

Most people build outside framed locos with the outside frames cosmetic, reason being, it gets very tight between the wheels and the cranks!

 

Personally, I would advise separate bearings with beams on top of them. There are several reasons for this, but mostly the fact that you can drop the wheel sets out easily makes fitting the gearbox, painting and maintenance simpler. Soldering the beams into the bearings might be slightly simpler at first construction, but you will be making life harder for yourself in the long run.

 

Working with ⅛" axles in S scale, I now use axle boxes of ¼" brass. These are held in some thick walled tube in the 3-jaw chuck of the lathe, for boring out the axle (actually, I just use a 3.15mm drill, followed by a ⅛" hand reamer held on the tailstock, and manually turn the 3-jaw). Whilst they are still there, they are faced off, then a narrow (0.020" or 0.5mm) groove is cut, a minimum of 0.020" (0.5mm back) from the outer face of the axle box. This doesn't have to be very deep as it's sole purpose is to stop the axle box sliding along the axle with respect to the frames. The box is then parted off, a bit further back - you can make these as long as you wish/need, but ⅛" is fine. More are then made!

 

The loco frames are made from 0.018" width material, and have a ¼" wide slot for each axle. These have to be very accurately cut/filed, but since you have a milling machine with DRO, you should be OK! They have to be a gnat's whisker wider than the box, but no more. The frame material is also used to provide the "guide strips" either side of the axle box slot, per the diagram below.

 

Obviously you would need to use different thickness, with 3/16" axles, but you get the idea.

 

I now make my coupling rods after I have made the frames. Using a digital calliper, I measure the distance between the outside of two adjacent slots and then over the inside of the same two slots. The average of these two measurements is the coupling rod centres, and I (very!) carefully mark out the rods to suit. Again, with your DRO-fitted mill, this should be very easy for you to do with 100% accuracy. I tried it this way after a "friend" told me I wouldn't be able to do it this way. I was extremely pleased to prove him wrong!

 

[5050]

I made some rods 'post chassis build' by measuring distances between axles insides, outside and centres and calculating the mean, using that to drill the holes.  Worked perfectly.

[Mol_PMB]

I have been drawing up some possibilities for a compensated chassis for this loco. I have to say this is getting me down a bit, it's adding greatly to the complexity and staring at the screen drawing stuff is too much like work. There's no point doing modelling if it's not fun!

Maybe it's just Friday evening gloom affecting me, and I need to put this aside for a few days. But at the moment my enthusiasm for a compensated chassis is at a low. And that's even before I get to the rods.

 

Note this drawing is a work in progress and not entirely self-consistent, I stopped some time after I had got fed up with it.

 

Perhaps I will spend the weekend trying to make progress on the layout instead, and see if I find some more enthusiasm next week.

I do really appreciate all the advice and ideas, thank you.

 

[Regularity]

He’s the chassis I built in 2014, standing atop the drawing I did in pencil and paper of the whole loco, which was only needed for frame outlines in this respect: mark the axle centres vertically, and horizontally, then scribe a line (in my case) ⅛” wide either side, and 5/32” (ok, 4mm) above, and cut close with a piercing saw. Then very carefully file and check, file and check, file and measure.

The pivot for the beams was marked, IIRC, to be about 3/16” above the axle centre line, meaning that the bottom of each beam was 1/16” below the beam’s own pivot. The beams were cut at the same time as the frame.

You don’t need twin beams at the rear, just a central pivot resting on the axle.

 

 

As you know the wheelbase, and have a milling machine with a DRO, you would be able to do all this based on a quick sketch on the back of an envelope, and then do the actual outline later.

 

If doing CAD is too much like work, well, you don’t have to do it that way.

 

Sadly, the loco never progressed any further.

[Mol_PMB]

Thanks again. 

 

I think my problem is that I had spent several weeks building up the confidence to build a simple rigid chassis, and now it feels like the goalposts have moved out of reach with the addition of compensation. I know it would be better. 

 

Using hornblocks seems to me to significantly increase the complexity, and I don’t have a lathe to make them either. Again, I can accept they would be better but I have limitations. 

 

But even just with rocking beams there are a lot of challenges in fitting everything in and keeping the geometry right. That’s why I wanted to do an accurate drawing and that was useful because the plunger pickups and the gearbox are constraints on the design of the rest. 

Also I think it has proved that I can fit cosmetic frames behind the wheels which would be my preferred approach.

 

I think I’ve got a better plan for the third axle with a kind of cannon box pivoted in the middle. I’ve found some bits that would suit but I didn’t get as far as drawing them. 

 

[Mol_PMB]

PS I’m not afraid of coupling knuckle joints, here’s one I was working on almost exactly a year ago:

 

The difference there is that it’s about 40 times bigger and I have a full machine shop to play with. If it wasn’t for COVID I’d be there working on a real loco instead of a model. 

The other difference is that setting up the horns with the faces for all four axles parallel within 5 thou took me over a year of weekends! I don’t want the model to take that long or it would never get finished. 

 

[Regularity]

1 hour ago, Mol_PMB said:

I think my problem is that I had spent several weeks building up the confidence to build a simple rigid chassis, and now it feels like the goalposts have moved out of reach with the addition of compensation. I know it would be better. 

I don’t have the confidence, nor would I know where to start, building a rigid chassis. A teenage experience with a K’s kit did that to me.
 

Quote

Using hornblocks seems to me to significantly increase the complexity, and I don’t have a lathe to make them either. Again, I can accept they would be better but I have limitations. 

 

Buy some ready made: I used to do that.

 

That’s big stuff: have Bachman gone very seriously large scale?

[Ruston]

12 hours ago, Mol_PMB said:

Thanks again. 

 

I think my problem is that I had spent several weeks building up the confidence to build a simple rigid chassis, and now it feels like the goalposts have moved out of reach with the addition of compensation. I know it would be better. 

 

 

 

Go DCC and you won't need all the complexity of compensation. It's not P4, so it doesn't need compensation to stay on the track and any interruption in electrical pickup is taken care of by the electronic flywheel a.k.a. Stay Alive.

[Mol_PMB]

It will be DCC, I’ve already ordered the sound chip and speaker. 

The motor has a large mechanical flywheel and as you say I can add a stay-alive too. 

One of the reasons I’m planning to have cosmetic outer frames is so the functional chassis can be dropped in and out simply, which gives the opportunity to modify/replace it later if needed. It also allows me to postpone the decision for another week or so as I work on the cosmetic frames. 

There are other benefits to the cosmetic frames too. 

 

In the mean time I am working on the layout and have just stuck down some of the track. 

[Ruston]

5 hours ago, Mol_PMB said:

It will be DCC, I’ve already ordered the sound chip and speaker. 

The motor has a large mechanical flywheel and as you say I can add a stay-alive too. 

One of the reasons I’m planning to have cosmetic outer frames is so the functional chassis can be dropped in and out simply, which gives the opportunity to modify/replace it later if needed. It also allows me to postpone the decision for another week or so as I work on the cosmetic frames. 

There are other benefits to the cosmetic frames too. 

 

In the mean time I am working on the layout and have just stuck down some of the track. 

What decoder/sound project will you be using? Something made for a BR Class 03, I presume?