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Author Topic: Belstone's Scratchbodge Studies  (Read 5079 times)

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Online Atso

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Re: Belstone's Scratchbodge Studies
« Reply #45 on: October 26, 2017, 11:02:29 am »
Nice work Belstone and a very unusual and interesting looking prototype to boot!

Looking at the drawings (I think I've got that edition of RM somewhere) the cab looks tiny while the bunker looks huge, was that really the case?

Turning attention to motors for a moment. Do you know if any of those 716 12v Farish type motors ever resurfaced on ebay? I managed to bag four at the time but would love to find a more consistent source of these.

Offline belstone

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Re: Belstone's Scratchbodge Studies
« Reply #46 on: October 26, 2017, 12:57:10 pm »
Nice work Belstone and a very unusual and interesting looking prototype to boot!

Looking at the drawings (I think I've got that edition of RM somewhere) the cab looks tiny while the bunker looks huge, was that really the case?

Turning attention to motors for a moment. Do you know if any of those 716 12v Farish type motors ever resurfaced on ebay? I managed to bag four at the time but would love to find a more consistent source of these.

An N15 is basically a J83 0-6-0T with an extra large bunker, so they do look slightly odd. Not much danger of this one being available RTR in my lifetime, manufacturers generally avoid Scottish prototypes even in OO let alone N. It would make quite a nice 3D printed bodyshell to fit the Poole chassis, if you run out of more worthy prototypes.  Or a North Eastern N10 which is very similar. I was toying with the idea of teaching myself whitemetal casting just for fun, but don't really have the time right now.

The glut of tiny motors seems to be drying up: i had a look the other day and got the impression there weren't so many about.

Richard

Online Atso

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Re: Belstone's Scratchbodge Studies
« Reply #47 on: October 26, 2017, 06:54:32 pm »
An N15 is basically a J83 0-6-0T with an extra large bunker, so they do look slightly odd. Not much danger of this one being available RTR in my lifetime, manufacturers generally avoid Scottish prototypes even in OO let alone N. It would make quite a nice 3D printed bodyshell to fit the Poole chassis, if you run out of more worthy prototypes.  Or a North Eastern N10 which is very similar. I was toying with the idea of teaching myself whitemetal casting just for fun, but don't really have the time right now.

The glut of tiny motors seems to be drying up: i had a look the other day and got the impression there weren't so many about.

Richard

Thanks for the information on the N15 and I agree that there isn't much chance of seeing an RTR version unless some enterprising group build a full size replica!

It is a shame that those motors seem to have been a short term deal, fingers crossed more will turn up in time...

An N10 has potential, I am familiar with this class having followed a blog of 2mm FS build from an etched kit (one off reduction from 4mm from what I can gather). However, I've had more than one person ask after an A8 (rebuilt by Gresley from H1 4-4-4s) so I might have a go at that if I can find a suitable chassis with a close to 6'6 by 6'6 coupled wheelbase and smallish motor...

White metal casting is something I'd like to play with as well and really should as I have a small quantity of white metal ingots to play with!

Online joe cassidy

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Re: Belstone's Scratchbodge Studies
« Reply #48 on: October 27, 2017, 06:37:13 pm »
white metal = silver ?

 :)

Offline Dorsetmike

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Re: Belstone's Scratchbodge Studies
« Reply #49 on: October 27, 2017, 07:01:55 pm »
White metal,  tin/lead and tin/copper alloys, heavy, low melting point which can vary with the percentages of each metal used. Has been used for casting loco bodies in kits, usually designed to fit a proprietary chassis.

Also used by Union Mills to cast their loco and tender bodies.
Cheers MIKE


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Offline belstone

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Re: Belstone's Scratchbodge Studies
« Reply #50 on: October 29, 2017, 10:56:37 pm »
A bit more work on the N15. The main bodywork bits are all in place and I have sorted out the body mounts so that it sits level on the chassis and doesn't come to bits when I pick the loco up.  It also has a front coupler although I'll probably need to change it for one with a slightly longer shank. I ended up replacing the boiler with a slightly larger one as there wasn't quite enough clearance for the motor.  So the boiler and tanks are both oversize. I'm hoping this does not spoil the appearance too much: I have seen much worse in N gauge.

With plenty of lead weight in the side tanks, smokebox and under the cab roof I finally got a chance to see how well the "Plastic Pig" chassis runs.  Unfortunately it limps like a three-legged donkey, with the rods binding badly enough to lift one corner off the track once every wheel revolution..  Opening out the conrod holes very slightly helped a bit but not enough, looks like the quartering is out on one wheelset although I can't see which one.  I'll try the optical quartering tool that I made for the "2P" project, failing that I'll have to rob the wheelsets from the Pannier for now.



Richard

Offline belstone

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Re: Belstone's Scratchbodge Studies
« Reply #51 on: November 02, 2017, 07:59:20 am »
A bit more progress last night on the N15:



Boiler fittings carefully salvaged from the GP tank body.  Front splashers need a bit more work but we're getting there.  Next job is to fit the handrails, along with the very distinctive long running boards below the bunker.  Boiler bands will have to come off as they are massively oversized, and in the wrong place due to working from the drawing rather than photographs.

Cab door aperture could do with opening out a bit, it looks like a keyhole in the picture.  The boiler and side tanks are maybe 1mm too high, but overall I think it looks a bit like an N15.  Here's one from Wikipedia.



Richard


Offline PeteW

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Re: Belstone's Scratchbodge Studies
« Reply #52 on: November 02, 2017, 01:48:10 pm »
Looks excellent to me. Very inspirational - thank you!

Offline belstone

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Re: Belstone's Scratchbodge Studies
« Reply #53 on: November 03, 2017, 08:08:11 am »
Here's a page I wish I had found earlier. I'll be adding details until Christmas now I have these photos to work from.

https://nbrlocomotives.livejournal.com/1711.html

Meanwhile contemplating my next project (either a J35 or J37 depending in how I feel, I have good drawings for both) and the fact that if I build all the locos I intend to build, I'll need six North British standard tenders (J35, J36 x 2, J37, D30, D34).  I might look at resin casting to make things easier.

Richard

Offline belstone

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Re: Belstone's Scratchbodge Studies
« Reply #54 on: November 05, 2017, 02:02:55 pm »
After adding the remaining body structural bits and some initial gap filling with liquid Tippex, the N15 has had a light coat of etch primer.  It hasn't come out badly - a few obvious flaws here, but it looks better in real life than in the photo.  Handrails next, then paint. Some N15s had vacuum brakes, some Westinghouse, and some had only the steam brake on the loco.  I'll need to find photos of both sides of my chosen loco, since (where fitted) the ejector pipe was on one side and the Westinghouse pump on the other. Thinking about future projects, wondering whether I can cobble together an Ivatt 4MT using a Crab chassis, Black Five body and the cab and tender (heavily modified) from a Minitrix 2MT. There is always the risk that Farish will announce a RTR model just after I have finished mine.



Richard

Offline Dr Al

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Re: Belstone's Scratchbodge Studies
« Reply #55 on: November 05, 2017, 06:46:10 pm »
wondering whether I can cobble together an Ivatt 4MT

If you mean the Ivatt 2-6-0:
https://en.wikipedia.org/wiki/LMS_Ivatt_Class_4

then the Farish Standard 4MT 2-6-0 is a far better starting point, as the Standard was essentially the same loco, albeit with BR standard fixtures and footplate design.

Cheers,
Alan
Quote from: Roy L S
If Dr Al is online he may be able to provide a more comprehensive answer.

Offline belstone

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Re: Belstone's Scratchbodge Studies
« Reply #56 on: November 10, 2017, 07:36:29 am »
As usual, what started as a simple scratchbodge has turned into an in-depth investigation into the dynamics of elderly Poole Farish mechanisms. This loco had been a dreadful runner in original form which I put down to lack of weight.  But even with the new body packed with lead it still stalled over points and sometimes on plain track, and had a noticeable wobble.  Close inspection showed that one wheel was lifting off the rails every revolution.  First thought was quartering, so I swapped the wheelsets for those from my 94xx Pannier, no difference.  Since then I have gone through the entire mechanism looking for faults and making small adjustments.

The biggest single improvement came from fitting jointed coupling rods.  I had a spare set, so I cut the two sets in half, filed down the centre journals so both rods would fit on a single crankpin, then secured the outer ends with 14BA screws in holes drilled through the centre of the plastic crankpins, which is less fiddly than it sounds.  The loco no longer lifts a wheel but if you look very closely you can see the rods flexing as it moves. 

So it now crawls along nicely on plain track (provided it is spotlessly clean) and doesn't wobble as much, but electrical pickup is nowhere near reliable enough for shunting work.  I suspect that as usual with rigid 0-6-0s, only three wheels are actually in contact with the rails at any one time.  I had ruled out Flexichas style compensation as the loco has the drive gear on the middle axle, but last night found a very interesting article by Stephen Harris on the 2mm Association website showing how he got round this problem.  I might try this next. This will require locating the centre axle rigidly: at the moment it seems to have a lot more play in all directions than is good for it, which might be part of the problem.  I dream of buying a milling machine and copying the Farish chassis in solid brass, with accurately machined axle slots.

http://www.2mm.org.uk/articles/new_comp_article/index.htm

Richard




Offline Dr Al

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Re: Belstone's Scratchbodge Studies
« Reply #57 on: November 10, 2017, 09:32:24 am »
Inherently, there's nothing wrong with the rigid chassis - I've used these chassis extensively for kitbuilds (including a J26, J27, J52, Aspinall saddle tank, an LMS Jinty from way back) with no trouble - they run lovely.

Even the ancientest versions of this chassis with 3 pole motors can run super slow and reliably:



If that was a 5 pole armature it would only be even better.

Now of course, there are plenty of dogs out there too, especially the old ones that haven't been looked after, but inherently the design is not the problem. Usually if there is a problem it's due to quartering on the Bachmann versions (there are some, and usually it's the middle wheelset that doesn't concur with the others), or bowed chassis which can occur if the chassis hasn't been located correctly in the metal bodies, and is then screwed home, bending it slightly and allowing the loco to see-saw on the central wheelset.

Inherently solid chassis are fine though - everything from old Farish 94xx chassis like this to the latest 08 shunters use them.

Electrofrog points are a must though.

Cheers,
Alan
Quote from: Roy L S
If Dr Al is online he may be able to provide a more comprehensive answer.

Offline belstone

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Re: Belstone's Scratchbodge Studies
« Reply #58 on: November 10, 2017, 02:26:22 pm »
Inherently, there's nothing wrong with the rigid chassis - I've used these chassis extensively for kitbuilds (including a J26, J27, J52, Aspinall saddle tank, an LMS Jinty from way back) with no trouble - they run lovely.

Even the ancientest versions of this chassis with 3 pole motors can run super slow and reliably:



If that was a 5 pole armature it would only be even better.

Now of course, there are plenty of dogs out there too, especially the old ones that haven't been looked after, but inherently the design is not the problem. Usually if there is a problem it's due to quartering on the Bachmann versions (there are some, and usually it's the middle wheelset that doesn't concur with the others), or bowed chassis which can occur if the chassis hasn't been located correctly in the metal bodies, and is then screwed home, bending it slightly and allowing the loco to see-saw on the central wheelset.

Inherently solid chassis are fine though - everything from old Farish 94xx chassis like this to the latest 08 shunters use them.

Electrofrog points are a must though.

Cheers,
Alan

Thanks for that, interesting that you say Bachmann-made chassis can have problems with quartering on the middle wheelset.  Both the sets I tried were Chinese-made and I've had a suspicion that the quartering on the centre axle might be slightly out although I couldn't detect it by eye, and the set from the 94xx seemed fine in that loco. I agree with you that Poole products can run very well indeed at slow speeds which is why this one is annoying me. With the rods removed it will happily spin its middle wheels on plain track without showing the slightest inclination to move, so if anything the chassis is bent up in the middle rather than down.

All other things being equal, a compensated chassis should have better electrical contact with the rails than a rigid one.  But how do you define rigid?  The wheelsets on the N15 waggle around in all directions (like pretty much any RTR N gauge loco, even the newest ones) so arguably it has some degree of compensation already.

Richard

Offline Dr Al

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Re: Belstone's Scratchbodge Studies
« Reply #59 on: November 10, 2017, 03:07:05 pm »
Generally I've found these Bachfar 94xx/GP tank chassis to be fairly good - particularly the motors which can be smooth and pretty much silent. Quartering more generally can need adjusted on Bachfar with larger drivers, but I've seen a couple of these that were wobblers. Usually this can be sorted out by swapping about the wheelsets (just the sets, not pulling wheels off axles - try all the possible combinations, one will generally be the best) and/or making sure the rods are absolutely perfectly straight - even the slightest bend can cause tight spots, and fractionally bent rods are surprisingly common on models in general.

If quartering is the cause it's most likely to be the central set that differs as it's a different tooling to the outer ones, and being geared it's likely set up on a different tool to the outers.

The wheelsets shouldn't have too much slop - laterally along the axis of the axles there will be some obviously (no big deal) which is restricted by the pickups, horizontally there should be relatively little, and vertically a little more. If, horizontally in particular, there is a lot of movement, particularly in the central set then it may be that the chassis is worn, or the axle itself is worn. I've seen this on some, and it seems correlated with certain bad applications of excessive lubricant that end up an abrasive mulch. Having said that, even those I've seen in this poor condition have been able to run reasonably decently after proper overhaul, albeit not as good as an unworn equivalent.

In terms of rigid - it's more than satisfactory in N - I'd define it as having no active axle movement or springing designed in. Obviously slop and tolerancing will allow some, but that's generally ok and actually desirable (to a level) to allow all wheels to drop onto the track. What you don't want is it balancing on the central set though, or the chassis bowed such that the central set has a clear gap between it and the rails. If the central set is just dropping onto the rails and no more then that's probably spot on, and allows for fractional upward bowing of the track (highly common on Peco turnouts at the frog) to be accommodated while running without risk of excessive frog drop.

Also be sure the pickups and wheel backs are absolutely clean as it's surprising how some sticking points can actually be related to dead spots in pickup per rotation due to dirt, rather than mechanical inaccuracy of the drive. Sometimes the blackened wheel backs need a good bit of running to polish up to get the best out of - usually good to lightly clean off any resulting residue from the wipers after doing this. Running is probably the best route to this as use of abrasives will simply leave scratches on the surface which will accumulate dirt more readily.

Cheers,
Alan
Quote from: Roy L S
If Dr Al is online he may be able to provide a more comprehensive answer.

 

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