The path of less resistance? J72 conversion

DougN
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Re: The path of less resistance? J72 conversion

Postby DougN » Mon Oct 18, 2010 2:22 am

UMMM That is looking really good Dave. The idea of having all the brakets soldered to the brakes and having the entire assembly "clip" to the chassis is a good one. I will now go through and have a look at the Q6's to see how Dave Bradwell has attacked the problem!
Doug
Still not doing enough modelling

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Russ Elliott
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Re: The path of less resistance? J72 conversion

Postby Russ Elliott » Mon Oct 18, 2010 10:10 am

DougN wrote:The idea of having all the brakets soldered to the brakes and having the entire assembly "clip" to the chassis is a good one.

Indeed. I had a brief but substantial disagreement with Bill over this matter a week or so ago. It seemed to me that it would be a logical extension of Bill's commendable approach (of not having the blocks tied to the beam) to have a proper keeper plate, to:
- keep the blocks in place;
- have the dummy springs as an integral part of the keeper plate etch;
- carry all the brake gear;
- provide a convenient place on which to mount collector gear.

A couple of 10BAs (fore and aft in the chassis) would be far simpler than having 12 bits of wire (or 14BA bolts) currently holding the dummy springs.

Bill would have none of the notion. I argued that the reality of most people's chassis construction practice is that wheels will need to be dropped in and out of the chassis in the construction phase on a regular basis (checking body clearances, tweaking back-to-backs, tweaking quartering, painting frames, etc, etc), but he maintained that was not what 'should' happen.

We agreed to differ.

David Knight
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Re: The path of less resistance? J72 conversion

Postby David Knight » Mon Oct 18, 2010 2:45 pm

Russ Elliott wrote: (snipped)
A couple of 10BAs (fore and aft in the chassis) would be far simpler than having 12 bits of wire (or 14BA bolts) currently holding the dummy springs.

Bill would have none of the notion. I argued that the reality of most people's chassis construction practice is that wheels will need to be dropped in and out of the chassis in the construction phase on a regular basis (checking body clearances, tweaking back-to-backs, tweaking quartering, painting frames, etc, etc), but he maintained that was not what 'should' happen.

We agreed to differ.


As it happens Russ I agree with you as I have found that tweaking a multitude of things is the order of the day. That said, this is still easier than on some frames where the bearings are held captive and the quartering has to be done while trying to peer through the frame itself.

I do have one little trick with the 14BA bolts that might be worth passing on. I tie trout flies in my non-railway hobby time and part of the kit is fly tying wax to make things stick better. A bit of this on the end of a jeweler's screwdriver helps minimise the number of screws sacrificed to the Great Carpet God often referred to in other posts ;)

Cheers,

David

simonmoore

Re: The path of less resistance? J72 conversion

Postby simonmoore » Mon Oct 18, 2010 3:02 pm

This chassis is really coming along now, I stupidly started mine after a session on nights at work & totally cocked up the connecting rods it looks like it's going to be either another kit or some seperate conncting rods from Comet. The chassis certainly looks the buisness though well done.

Simon.

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Mike Garwood
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Re: The path of less resistance? J72 conversion

Postby Mike Garwood » Mon Oct 18, 2010 5:37 pm

Why not give Bill a ring and see if he has a spare set...ya' just never know..

Mike

David Knight
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Re: The path of less resistance? J72 conversion

Postby David Knight » Mon Oct 18, 2010 9:07 pm

As promised a pic of the finished gear. Everything springs into position and holds firmly in place or off as required. Now to find a safe place to store it while I get on with the rest.
brake rigging detached.jpg


Hopefully this should clarify any obscure references made in earlier postings :)

Cheers,

David

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Will L
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Re: The path of less resistance? J72 conversion

Postby Will L » Mon Oct 18, 2010 10:53 pm

Russ Elliott wrote:... I had a brief but substantial disagreement with Bill over this matter a week or so ago. It seemed to me that it would be a logical extension of Bill's commendable approach (of not having the blocks tied to the beam) to have a proper keeper plate, to:
- keep the blocks in place;
- have the dummy springs as an integral part of the keeper plate etch;
- carry all the brake gear;
- provide a convenient place on which to mount collector gear.

A couple of 10BAs (fore and aft in the chassis) would be far simpler than having 12 bits of wire (or 14BA bolts) currently holding the dummy springs.


Have to say I'm not convinced about the desirability of a keeper plate Rus. I think your right about the multiple attachment point for the springs, but as I'd rather get rid of the keeper plate all together I don't really like the loose axle block approach.

So what about the dummy springs, a neat trick I recently learned from Adrian Prescott is to attach the dummy under hung spring to the axle block. Not only is it prototypical in its way but it means they just don't get in the way if you want to drop the wheels out.

Clip on break gear as above does it for me, so with axle block retained by the CSB.... bingo no keeper plate.

Will

simonmoore

Re: The path of less resistance? J72 conversion

Postby simonmoore » Tue Oct 19, 2010 5:32 am

Mike Garwood wrote:Why not give Bill a ring and see if he has a spare set...ya' just never know..

Mike



Good idea that Mike i'll give him a buzz later today see if i can sort anything out.

Simon.

David Knight
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Re: The path of less resistance? J72 conversion

Postby David Knight » Thu Oct 21, 2010 2:14 am

While we are on the topic of siderods, it appears that the assembled Bedford rods are thicker than the Gibson collars are deep. The difference is not huge so a bit of file work should answer but I thought it worth mentioning.

Cheers,

David

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Mike Garwood
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Re: The path of less resistance? J72 conversion

Postby Mike Garwood » Thu Oct 21, 2010 7:58 am

Ahh, but which one has the correct measurements? Thickness and width...or are they both wrong in some respect?

Mike

David Knight
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Re: The path of less resistance? J72 conversion

Postby David Knight » Thu Oct 21, 2010 1:04 pm

Mike Garwood wrote:Ahh, but which one has the correct measurements? Thickness and width...or are they both wrong in some respect?

Mike

Well, I'm not sure which is correct but the thickness of Bill's rods is probably closer to the actual thickness of the real thing, Bill being a precision kind of guy, and the Gibson collars, bushings whatever you want to call them are more of a 'one size fits most' kind of thing. All of which still means I have some filing ahead of me, unless I turn up a new set of bushings...? Stay tuned... Oh, and I did consider putting the retaining collars on in reverse but was not happy with the idea as they were too hard to tighten properly.

Cheers,

David

David Knight
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Re: The path of less resistance? J72 conversion

Postby David Knight » Sun Oct 24, 2010 6:36 pm

The coupling rods are sorted now. A few strokes with a file and a bit of careful measurement in between and all now runs smoothly. I have also added the torque reaction link and removed a bit of part number number 5 from Bill's list, part of the ashpan assembly. Also removed, the motor shaft at the brush end to provide clearance for the boiler weight. A few pics to illustrate all this.
torque reaction link etc..jpg

The link should be fairly plain coming out of the cross member. The modification to the ashpan is more what isn't there as part of it was removed to keep the gearbox extension from fouling. This is not going to be a problem if you follow Bill's suggestion of a vertically mounted motor. I'm just not sure which motor that would be as space is at a premium.
hooked up.jpg

Altogether now, the hookup of the link should show under the motor tight in by the gearbox.
bottom view.jpg

Finally a look at the mechanism in place on the body. I have added a plastic angle across the back to support the rear of the frame. The weights can be seen on the tanks and the coal bunker, 3/4 oz or 21g per side and 1/2 oz, 14g on the bunker plus the cast boiler bottom from the Mainly Trains kit rounds things out at an all up weight (so far) of 4.21 oz or 119.2g. This compares with a weight of 5 3/4 oz for Iain Rice's conversion done way back in MRJ 10. I still have a cab interior and crew to add so we're edging up there. :wink:

Next on the show, pickups. I'm thinking the best placement will be front and rear drivers but other helpful suggestions will be entertained.

Cheers,

David

Philip Hall
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Re: The path of less resistance? J72 conversion

Postby Philip Hall » Sun Oct 24, 2010 7:50 pm

I'm not a springing man, but on pickups there's only one rule. On every wheel at least on an 0-6-0 and if it's got a tender, at least two more on each side. The more pickup you've got, the less likely you'll have a stall or unsteady running. Two axles on a six coupled chassis is not enough, even if it's sprung or compensated.

I use 0.3mm brass wire with a few coils wound into it, bearing at right angles to the edge of the flange. They're soldered to two brass wire busbars running most of the length of the chassis. Bearing on the edge of the flange means contact is on the cleanest part of the tyre, and also will not prevent any movement up or down of a moving wheelset. I don't use phosphor-bronze, (on steel wheels, at least, it's fine on nickel-silver) as Mike Sharman told me years ago that it oxidises when in contact with steel. I've never had a problem with brass.

Philip

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John Bateson
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Re: The path of less resistance? J72 conversion

Postby John Bateson » Sun Oct 24, 2010 9:20 pm

Bother!
On looking at the latest pictures I thought the knuckle was incorrect on the coupling rods, sure that it was behind the centre wheel and not ahead of it.
So I checked both my J72s and found that I have one of each set up. Just shows what you can miss when in a careless mode - two kits, one a Ks and the other a Bachmann conversion but both via AG frames and coupling rods.
I'm sure that the kit from BB must be correct and have added an extra line to my to-do list.
As I said - Bother!

John
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David Knight
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Re: The path of less resistance? J72 conversion

Postby David Knight » Mon Nov 15, 2010 12:44 am

The final stage (for the moment) is the addition of the pickups which should have happened a while back but the outside world keeps getting in the way :?. Anyhow, I followed fairly standard practice and epoxied suitably gapped copperclad strips across the frames and made up stylus style pickups to bear on each wheel from 30 swg/ 0.315mm/ 0.0124" nickel silver wire. One might think that this is straight forward but it is important to make sure that the wire does not exert too much force on the tread or otherwise the ride of the engine will be affected (don't ask how I know :( ). Flexible wire was used to connect the copperclad strips to each other, the motor hooked up and the whole rig was taken for a test drive. After some minor tweaks it was declared fit for service and will now join the queue for the paint shops while I get on with the upperworks. I attach a couple of pics from different angles in the hope they will answer any questions and thank you all for your kind attention and thoughtful comments.

Cheers,

David
side on view.jpg

elevated view.jpg

simonmoore

Re: The path of less resistance? J72 conversion

Postby simonmoore » Tue Nov 23, 2010 5:30 pm

I'm shocked great thread & really enjoyed watching this come together but i am actually shocked either someone has mentioned my problem regarding the connecting rods or Bill Bedford has seem my problem. I've opened a package today with some spares in & i didnt even ask for them :o Now if that isnt 110% perfect customer service i don't know what is. I shall be contacting Bill to personally thank him for the spares because i wasnt expecting anything like that.

Many thanks

Simon.

David Knight
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Re: The path of less resistance? J72 conversion

Postby David Knight » Wed Dec 08, 2010 10:17 pm

A couple of short updates. I changed the pickups from the nickel silver to phosphor bronze (28 SWG/0.3 mm/.015") as I found that the N/S seemed to have lost some of its spring. Whether this was due to annealing from the soldering process or just a characteristic of the metal I'm not sure but the PB is holding up well so far.

I have been adding bits to the cab (floor, tank ends, handrails, backhead, regulator, gauge glasses, handwheel, and reverser. I'm also hanging the handrails to lighter gauge wire (0.33 mm) & replacing the original posts (Gibson short & medium) for appearance sake. Shunter's steps and extra handrails have also been added along with some brass safety valves and eventually a brass whistle. Still to come are the cab doors and the handbrake standard. The paint shop is still not ready for the work yet so things are a bit bright.

Cheers,

David
J72 cab etc.jpg

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Andy W
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Re: The path of less resistance? J72 conversion

Postby Andy W » Thu Dec 09, 2010 9:29 am

Nice work, David.

One detailing item that isn't as easy to find these days is coal! At least not here in London. I'll have to make a trip to a preservation railway and do some foraging.

Andy
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Build a wall along the Herefordshire border and make them pay for it.

David Knight
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Re: The path of less resistance? J72 conversion

Postby David Knight » Thu Dec 09, 2010 9:11 pm

Thanks Andy, I knew there was another thing to do - coal! Strangely enough there are people who will sell you a small bag at an outrageous price at some shows, just as well it is not needed for house fuel. :o

Cheers,

David

David Knight
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Re: The path of less resistance? J72 conversion

Postby David Knight » Sun Mar 13, 2011 8:43 pm

An update. I have been running in the engine in service for a while and generally tweaking performance before applying the finish to the frame. One thing I was not happy with was the pickups or to be more specific the top acting ones as they rather defeated the purpose of the springs. Now, one of the great virtues of CSBs is the fact that all wheels are in contact with the rails at all times, so, good for tractive effort and pickup. After some thought and study I decided to make a modification and rig pickups on only the outer wheels. I came up with the following arrangement.
now you see it.jpg

The front and rear wheels now do the pickup and when the body is in place the steps keep everything tucked out of sight.
now you don't.jpg

I shall give this a trial and report back.

Cheers,

David

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Flymo748
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Re: The path of less resistance? J72 conversion

Postby Flymo748 » Mon Mar 14, 2011 6:59 am

davknigh wrote:The front and rear wheels now do the pickup and when the body is in place the steps keep everything tucked out of sight.
now you don't.jpg

I shall give this a trial and report back.


I love the dodge with the steps hiding the pickup :-)

That's really cleverly thought out, and just the sort of thing that I tend to forget!

Flymo
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David Knight
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Re: The path of less resistance? J72 conversion

Postby David Knight » Sun May 08, 2011 9:54 pm

Having given things a fair trial I thought some final thoughts might be in order. For anyone looking for a straightforward path to a) P4 and b) CSBs I would recommend this frame (usual disclaimer). Bill's suggestions are quite useful and the frame really is self jigging if you take your time and study the drawings before starting off. The pickups behind the steps idea works because all the wheels stay on the rails all the time which is the whole idea of CSBs in the first place. You may have to do some fettling to get your choice of gearbox to stand clear of the ashpan but maybe that's just the way mine worked but it was not an insurmountable problem. To sum up I am a satisfied customer and would go this route again.

Cheers,

David
J72 at work.jpg
J72 at work.jpg (91.32 KiB) Viewed 7017 times

Picture courtesy of Mark Stapleton

tmcsean
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Re: The path of less resistance? J72 conversion

Postby tmcsean » Mon Feb 20, 2017 10:01 am

I am finishing one of these off as one of the BR-built engines that were briefly and unhappily sent to Ipswich shed in the 50s. Unlike the NER and LNER-built engines, these had a very visible hopper sandbox below the bunker. They are very visible and rather than build them I would much prefer a cast or lost wax matching pair. None of the usual suppliers seems to have anything like. Does anyone on the Forum know of a source?
Tony McSean


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