some other things

andrewnummelin
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some other things

Postby andrewnummelin » Mon Apr 18, 2016 5:15 pm

As a change from working on signals, I've started to use some of the things learnt at Great Missenden together with helpful information from other parts of this Forum. As the weather has turned a bit chilly I thought I'd aim for some heat and set off on the road paved with good intentions...
- do some 3D drawing and have a couple of things printed that I feel confident I could not make by other techniques
- build another outside framed loco and keep the coupling rods within the loading gauge (my 0-6-4T derails when it meets a ground signal!)
- as light relief, rebuild some old "00" models to P4 - a couple of these were built over half a century ago (will the Ebbw Vale wagon be heavy enough for sprung suspension?)
- try to get some parts laser cut and etched (but that will take us back to the PC&N later this year I hope).

So today my workbench is unusally tidy!
workbench09.jpg

I now have to "design" spacers that will strighten up the frames when they are put together.
Regards,

Andrew Nummelin

andrewnummelin
Posts: 238
Joined: Mon Jul 21, 2008 9:43 am

some other things - outside frames

Postby andrewnummelin » Thu May 12, 2016 8:47 pm

Some progress to report.
The Birmingham Corporation Water Works wagon now has new running gear and the missing bits of strapping have been replaced, it has joined the Cambrian wagon waiting for a trip to the paint shop.
I "finished" the drawings for the loco boiler mountings and these have gone off to be printed. The chimney and safety valve cover lips are thinner than desirable for printing - fingers crossed that they turn out OK, othewise I'll have to get the lathe out.....
The loco frames are no longer wavy having been assembled with the help of the Avonside Chassis2 jig and Will's series on leaping bucks http://www.scalefour.org/forum/viewtopic.php?f=96&t=2932&p=45072&hilit=buck#p45072 - many thanks Will for the tutorial.
I had problems with the last loco I made where I milled the coupling rods out of steel - I found it difficult to avoid distortion and cutting the fork was a nightmare. The final result was clearly sub-standard. So this time I thought I would try a lamination technique - very tedious and I'm not convinced that it was better on balance. The fork was easier but the bosses poorer and a real pain to file up. I'll have to think of something different next time - or work on improving my milling and filing skills. Anyway here are a couple of photos to show the drilling, bits and the completed rods.
rods1.jpg

I started each hole using a centre drill but I wonder now if it would not have been better to use a proper spotting drill.
rods2.jpg


rod3.jpg


I had a thought about keeping hornblocks and bearings together and reducing the chance of dropping things so I stuck some cocktail sticks into a block of foam and keep the bits on that. So far, so good!
foam.jpg


Chassis assembly was essentially as described in the Chassis2 instructions, but slightly modified to handle the outside frames.
Fit bearings and hornblocks to the outside frames using the jig.
Add spacers to go between the outside and inside frames - these were held with tweezers while soldering as their nature didn't allow alignment by the cross frame. I'm sure there must be a better way of doing this.
Using an Exactoscale jig, solder the inside frame to the spacers. Alignment was by eye as there are no bearings in it.
insideframe.jpg

Turn the frame pair through 90 degrees and add conventional spacers to the inside frame - I believe these were from Alan Gibson.
spacers.jpg

Then using the Chassis2 jig add the other pair of frames in the conventional way to give the "finished" chassis.
chassis1.jpg

Only two spacers are needed as the pairs of frames form a sort of box girder and are pretty rigid.
The three bits of wire across the inside frames are the future supports for the brake hangers.
Next will be persuading the gearbox, wheels, axles and cranks to go together properly.... it's a small loco so the clearances are going to be tight!
Regards,

Andrew Nummelin

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Guy Rixon
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Re: some other things - outside frames

Postby Guy Rixon » Fri May 13, 2016 11:21 am

andrewnummelin wrote:I started each hole using a centre drill but I wonder now if it would not have been better to use a proper spotting drill.


Please explain about "proper spotting drills", they sound very useful. I know what a centre drill is for and how to mis-use it for spotting. If there's a better tool for this where would one get it?

Cheers,
Guy

andrewnummelin
Posts: 238
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Re: some other things - outside frames

Postby andrewnummelin » Sun May 15, 2016 6:55 pm

[quote="Guy Rixon"
Please explain about "proper spotting drills", they sound very useful. I know what a centre drill is for and how to mis-use it for spotting. If there's a better tool for this where would one get it?

Cheers,
Guy[/quote]

Guy,
I've put a reply in the "Other Workshop Practice" subforum as I thought it more likely to get more information there. See
http://www.scalefour.org/forum/viewtopic.php?f=18&t=4864
Regards,

Andrew Nummelin

andrewnummelin
Posts: 238
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Re: some other things

Postby andrewnummelin » Thu May 19, 2016 6:52 pm

Work on the chassis has progressed far enough for me to find that clearances are so tight that there is a risk of CSB wire rubbing the wheel rims - so the spacers between the inside frames are going to be split electrically. Pity I didn't see this coming as I should have fitted split axles to avoid the need for a wire pick-up installation (that is going to be fiddly on this loco).

My first experiment at drawing for 3D is back from the printers - the only bits that have not come out as well as I dreamed were the spring hangers, they were just too fragile (as I feared they would be). I had hoped to avoid the tedious fiddle of making a couple of dozen tiny bits of metal.
DSC03443.JPG

Now these bits have arrived I really must get on and build the rest of the loco for them to sit on.
Regards,

Andrew Nummelin

andrewnummelin
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Re: some other things - csb's and outside frames

Postby andrewnummelin » Tue Jun 14, 2016 7:09 pm

Work has been going on with the chassis and bodywork - more on that later.
Further checking of clearances revealed that I had built the inside frames too close together which in turn caused the outside frames and bearings to be too close to the wheels.... so dismantle the chassis and rebuild with the outside frames a bit further apart. No shorting problems now, but the final result is, as I feared it might be, out of gauge! Pity the poor ground signals:
DSC03554.JPG

DSC03553.JPG


I measured the distance over the crankpin nuts as around 38.5mm, considerably more than I estimated (36.6mm http://www.scalefour.org/forum/viewtopic.php?f=19&t=4890#p45915). The crankpin bushes could be shortened a bit but I find it difficult to see where else things could be thinned down.

DSC03555.JPG

The cranks might be a candidate for thinning, but this would probably mean making new ones - there's not much holding the screws in these Gibson ones after countersinking the back.
(Model photography is useful - it's obvious why the chassis rocked a bit about the centre - one really should put the wire through all the supportss!)

All being well I'll bring it along to the AGM and see if the gurus can come up with suggestions of how I can do better next time.
If I can get enough done in the next couple of days, the body might go along as well as the chassis won't work properly without it..... I wonder what the clearances are like on Little Mill.
Regards,

Andrew Nummelin

andrewnummelin
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Re: some other things - 3D printing & CSBs

Postby andrewnummelin » Fri Jun 17, 2016 9:13 pm

The paint is drying and the glue setting ...... so I should be able to box it up in the morning and take it to the AGM where I hope I will learn what I should have done differently!

This project was a bit of an experiment - firstly putting to use some of what I learned at Great Missenden in March has been a success, secondly my second attempt to make a good outside framed chassis has been anything but a success.
3D printing has enabled me to produce boiler fittings that I could not have done any other way.
boilerfittings.jpg

(I must improve my painting... )

The chassis has continued to give problems: tight clearances together with poor modelling skills have resulted in lack of free running. A crank pin came loose, fouled the frame and the stress caused another crank to slip on its axle: an axlebox did not sit proud of the frame and this allowed a crank rub against rivets on the frame and the other crank on the driven axle lost its quatering; the CSB carrier on one wheel was higher than the others (how??) and fouled the underside of the footplate giving a nice see-saw effect; finally, and more of a worry, the restraint on the gearbox to stop it revolving round the axle seems to restrict the action of the CSB spring.
If I can get help to sort these problems out I still have one other thing to do and that is to work out how to run the wiring differently so the DCC chip can be fitted in the steam chest/smoke box rather than under the bunker: the balance of the loco is wrong so I need to add weight to the rear but the gearbox is in the way of running wires to the front.
If it runs tomorrow I wonder if the out-of-gauge crankpin nuts will cause chaos.
Regards,

Andrew Nummelin

Knuckles
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Re: some other things

Postby Knuckles » Fri Jun 17, 2016 9:55 pm

As I'm still a P4 n00b in many ways and as I have mostly built fixed axles I can't help but I do find your posts most interesting, that I will say. Hope to see more and also hope you get the loco running well. 3DP helps loads. Nice to see some more pre-Groupies.
“He who dares not offend cannot be honest.” Thomas Paine

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Mostly offering Loco kits & bits in 4mm.
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Will L
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Re: some other things - 3D printing & CSBs

Postby Will L » Fri Jun 17, 2016 10:06 pm

andrewnummelin wrote:...finally, and more of a worry, the restraint on the gearbox to stop it revolving round the axle seems to restrict the action of the CSB spring...


Are Torque Reaction links. You can get away with all sorts of things on a chassis that runs reasonably smoothly, but if you are having trouble getting the chassis to run, an inappropriate placed Torque reaction link will definitely do as you describe. I have looked at your photos and I'm afraid I can't find yours. For further info on see this thread Torque Reaction Links - Suspending The Driven Axel

I take it you now have the CSB spring through all the fixed fulcrums.

Armchair Modeller

Re: some other things

Postby Armchair Modeller » Fri Jun 17, 2016 10:54 pm

I do like the boiler fittings - is there any chance some might be available, please?

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Paul Townsend
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Re: some other things

Postby Paul Townsend » Sat Jun 18, 2016 5:51 am

Now your loco takes on some character from the proper period!
However, apart from telling us it's wheel arrangements, I don't think we know what engine it is. Please share.

andrewnummelin
Posts: 238
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Re: some other things

Postby andrewnummelin » Sun Jun 19, 2016 4:29 pm

This is the example of my poor modelling - I really must stop rushing to meet self imposed deadlines by not leaving everything till the last minute:
New-Out99997-Pyramid Do Stack[1,0,1].jpg

According to the RCTS this loco started as a banker from LLanhilleth to Crumlin on the Taff Vale extension of the Newport, Abergavenny and Hereford Railway but was later used from Pontypool Road banking coal trains going north so would have run through Little Mill.
Can anyone prove that the livery is wrong?

My thanks to Tim & Paul who discovered some of my mistakes, helped put some rignt and gave some excellent ideas of how to do better in the future. However I'd still managed to have a loco that was so stiff that when we tried it out on Little Mill I managed to blow the chip! A subsequent quick test at Maindee on DC proved that there is still something preventing free running. The only thing I can think of at the moment is that some Loctite got behind the crankpin nuts - the one thing I hadn't checked since Friday night. I think now is the time to stop rushing at getting something finished and to go back, take things apart, and start putting them back slowly and carefully; but this will have to wait until the neglected garden has been taken in hand!

I'll post a bit about the 3D printing on a more appropriate forum later in the week when our visitors have left.
Regards,

Andrew Nummelin

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Paul Townsend
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Re: some other things

Postby Paul Townsend » Sun Jun 19, 2016 8:26 pm

Lovely!

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randallb
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Re: some other things

Postby randallb » Sun Jun 19, 2016 9:00 pm

It looked absolutely fantastic set up on Little Mill Jcn at the AGM.
Randall

andrewnummelin
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Re: some other things

Postby andrewnummelin » Wed Jun 22, 2016 8:50 pm

Armchair Modeller wrote:I do like the boiler fittings - is there any chance some might be available, please?


I've posted a bit about them at http://www.scalefour.org/forum/viewtopic.php?f=7&t=4936#p46444 - let me know if you want any more information.
Regards,

Andrew Nummelin


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