Hornby J94

dave_long
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Joined: Mon Feb 02, 2009 9:21 pm

Hornby J94

Postby dave_long » Sun May 20, 2018 9:44 am

Hi a couple of questions regarding the Hornby J94.
The Hornby model has its drive set with left hand leading or atleast the version I have is, and the DJM model appears to have right hand lead, I know a few different companies built the J94s so I was just wondering which is correct or is it both but it depends etc? I did have a search but couldn't find an answer.

The other question is regarding the Alan Gibson conversion set, the axles are different by 0.1mm and that means the Gibson axles don't fit through the axle bearing tube, what's the best way to correct this size error? Reamer, broach or replace with other tubing cut to size. The drive gear being plastic fits with a little help, but the 2 other axles need the bearing tubes. It a substantial size bearing.
IMG_20180520_103843.jpg
IMG_20180520_103843.jpg (55.73 KiB) Viewed 2677 times


Thanks Dave.

Porcy Mane
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Joined: Wed Apr 11, 2012 4:55 pm

Re: Hornby J94

Postby Porcy Mane » Sun May 20, 2018 2:46 pm

The copy of Hunslet GA I have, the plan view shows the crank axle, with the R.H big end fully exposed (TDC) the LH big end is trailing at the three o clock position.

The Vulcan foundry drawing shows the same but strangely in the front elevation both coupling rods are shown at the six o clock position. (BTC)

P

Alan Turner
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Joined: Sun Jul 20, 2008 4:24 pm

Re: Hornby J94

Postby Alan Turner » Sun May 20, 2018 6:49 pm

dave_long wrote:Hi a couple of questions regarding the Hornby J94.
The Hornby model has its drive set with left hand leading or atleast the version I have is, and the DJM model appears to have right hand lead, I know a few different companies built the J94s so I was just wondering which is correct or is it both but it depends etc? I did have a search but couldn't find an answer.

The other question is regarding the Alan Gibson conversion set, the axles are different by 0.1mm and that means the Gibson axles don't fit through the axle bearing tube, what's the best way to correct this size error? Reamer, broach or replace with other tubing cut to size. The drive gear being plastic fits with a little help, but the 2 other axles need the bearing tubes. It a substantial size bearing.
IMG_20180520_103843.jpg

Thanks Dave.


If the difference is 0.1mm then use a reamer.

regards

Alan

dave_long
Posts: 63
Joined: Mon Feb 02, 2009 9:21 pm

Re: Hornby J94

Postby dave_long » Sun May 20, 2018 7:15 pm

Porcy, thanks for the info from the hunslet drawings.

Alan.
Yes the original axles are 2.36mm and fit smoothly through the bearing which I've tried to measure and believe it to be 2.40mm, the Gibson axles measure 2.46mm.
Would I need a straight/parallel reamer as the bearing is just under 8mm long? Would a 2.5mm reamer give a true 2.5mm?

Thanks.

Alan Turner
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Joined: Sun Jul 20, 2008 4:24 pm

Re: Hornby J94

Postby Alan Turner » Sun May 20, 2018 10:31 pm

dave_long wrote:Porcy, thanks for the info from the hunslet drawings.

Alan.
Yes the original axles are 2.36mm and fit smoothly through the bearing which I've tried to measure and believe it to be 2.40mm, the Gibson axles measure 2.46mm.
Would I need a straight/parallel reamer as the bearing is just under 8mm long? Would a 2.5mm reamer give a true 2.5mm?

Thanks.


It should do as that is what they are made to do. Also a 2.5mm shaft won't fit in a 2.5mm hole so the 0.04mm undersize is needed.

regards

Alan

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Hardwicke
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Re: Hornby J94

Postby Hardwicke » Mon May 21, 2018 11:01 pm

When I converted mine around 10 years ago now, I used standard Gibson wheels and no conversion set as far as I remember. Apparently bushes were available for the coupling rods but actual Austerity 0-6-0ST ones were not available so I chose to use WD 2-8-0 ones as they had the same spacing. They look far better than the Hornby ones. Pipework under the cab thinned to allow clearance. Standard Hornby mechanism. It is presently in for a service after failing at Nottingham in March.
Builder of Forge Mill Sidings, Kirkcliffe Coking Plant, Swanage and Heaby. Still trying to "Keep the Balance".

dave_long
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Re: Hornby J94

Postby dave_long » Tue May 22, 2018 6:51 am

Hardwicke
The conversion kit really is just a set of wheels and axles at 2.5mm, designed to fit the Hornby bearings but don't quite. Did you not use the axles bearings or did you still drill them out?
The coupling rod for the 2-8-0 I presume being Gibson is jointed on the crankpin? Has that ever given an issue? I'm not upto creating the articulation off the crank pin just yet.

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grovenor-2685
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Re: Hornby J94

Postby grovenor-2685 » Tue May 22, 2018 8:23 am

There must be variants of the chassis, mine does not have any such tube bearings.
Regards

dave_long
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Re: Hornby J94

Postby dave_long » Tue May 22, 2018 10:52 am

I had started to wonder whether Hornby had altered the chassis as I've looked in the usual places and no one had mentioned such issues. Photos below. The gear is fitted to a AG axle, and you can see the Hornby axle with tubular bearing and the bearing in its seating.

IMG_20180522_114831.jpg
IMG_20180522_114831.jpg (171.02 KiB) Viewed 2353 times


IMG_20180522_114859.jpg
IMG_20180522_114859.jpg (234.72 KiB) Viewed 2353 times

dave_long
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Re: Hornby J94

Postby dave_long » Tue May 22, 2018 12:17 pm

Keith.
Did you use the original coupling rods or did you replace them? I've read that some people bush the rods and some that haven't. I am tempted by the WD rods though. But as I have the bushes and rods already I may just solder them up anyway.

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jim s-w
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Re: Hornby J94

Postby jim s-w » Tue May 22, 2018 1:10 pm

Do you actually need the bushes at all Dave?

dave_long
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Re: Hornby J94

Postby dave_long » Tue May 22, 2018 1:31 pm

Jim,
Probably not, the rod bushes are not part of the list of other bits required for the AG conversion set, where they are a requirement if you buy a set for a Bachmann pannier. I hadn't planned on using the bushes for that reason, but I have a set because of a planned pannier tank conversion I haven't done yet.
But after reading a few people's notes on converting the J94 that there was a lot of slop in the rods, I thought perhaps it might be wise. I'll open the crank pin packet tonight and see what the slop is like.

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grovenor-2685
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Re: Hornby J94

Postby grovenor-2685 » Tue May 22, 2018 2:18 pm

dave_long wrote:Keith.
Did you use the original coupling rods or did you replace them? I've read that some people bush the rods and some that haven't. I am tempted by the WD rods though. But as I have the bushes and rods already I may just solder them up anyway.

I fitted replacement rods, don't remember now where they came from.
Just removed the keeper plate to confirm, definitely no such bearings, the spring for the centre axle bears directly on the axle.
DSCF2219.JPG

Note, cosmetic lead frame on each side to fill the gap behind the wheels and add weight.
Also widened the keeper plate to bring the brake shoes out to the right place, cut in 3 and reconnect with plasticard.
DSCF2221.JPG

dave_long
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Re: Hornby J94

Postby dave_long » Tue May 22, 2018 2:53 pm

Thanks Keith.
Definitely a change in design then, the spring has gone too, which isn't helpful. The tubular bearing is a friction fit so the chassis block has been altered to accommodate them. Hopefully the reamer will sort the bearing tube.

dave_long
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Re: Hornby J94

Postby dave_long » Mon May 28, 2018 4:32 pm

Keith
Did you glue, or tap and screw the lead to the side frames, I've found a source of 1.8mm flashing and thought I'd try this as I have to remove the main weight to fit an RC battery.

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grovenor-2685
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Re: Hornby J94

Postby grovenor-2685 » Mon May 28, 2018 8:59 pm

Usually I have drilled and tapped the main frame and screwed the lead on, I do remember trying out a glued job but don't remember now which loco it was. I'll have a look for pictures.
No pictures showing that but I've had the wheelsets out to have a look. No screws so that is the one I tried with glue. The lead does need careful fitting around the pick up wipers to avoid any unwanted contact.
Regards
Last edited by grovenor-2685 on Mon May 28, 2018 9:16 pm, edited 1 time in total.
Reason: Confirmation of glueing added.

dave_long
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Re: Hornby J94

Postby dave_long » Tue Jun 05, 2018 7:27 pm

Well with the tubular bushes sorted, attention turns back to the coupling rods. In the AG price list it doesn't say the J94 requires the coupling rods to have bushes to narrow the hole, unlike it does for the Bachmann pannier.
However in the crankpin instructions, it states both of the following, the coupling rod must be a slack fit over the crankpin bush, but it also states that the coupling rod should be opened out to 1.5mm. But the holes in the J94 rods are 2.5mm. I feel that having an extra 1mm here is probably too much slack and not a good thing? I think I might fit the extra bushes...

Philip Hall
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Re: Hornby J94

Postby Philip Hall » Tue Jun 05, 2018 11:21 pm

I think this must be a mistake in the instructions. Mostly Hornby rods have a 2.5mm hole to clear their larger size crankpin, apart from the 08 shunter which has smaller crankpins. The AG conversion bush brings this down to 1.5mm. The AG crankpin is a touch under this diameter, and I always open the hole, once the bush is soldered in, to 1.6mm, which gives a nice running clearance, a little tighter than the engine as supplied, but not too tight. Beware also that holes in RTR coupling rods, even from the same manufacturer, can vary a little, so the AG conversion bush can be a bit sloppy in the hole. In these cases I use some 2.5/1.6mm brass tube to bush the rod.

Philip

dave_long
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Re: Hornby J94

Postby dave_long » Wed Jun 06, 2018 5:40 pm

Thanks Philip.
Interesting though on this Hornby coupling rod, the holes on the 1 driving axle are smaller at 2.2mm, seems a lot of effort to go to in the manufacturing process. Annoying that I have to open them out to then bush them to narrow the hole.


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