Finney A3 - Spearmint

[3 link]

Hi Christian,

 

Thank you for posting this complete build, I have just one question ? I cannot see from the photo of the nearly finished loco above exactly how close you have managed to get the brake shoes to the wheel rims. It's just that as all the brake rigging is cast there cannot be much in the way of any flexing and the fact that you are using Slaters wheels, I would think it must be very hard to get them very close together. I have used nickel silver 0.7mm rod in the past to spring the brake gear into place once the wheels are fitted. But surely it's near impossible to fit the wheels after the brake shoes are in place because of the wheel flanges and the way Slaters wheels are fitted If you get my drift . If there is a method of getting round this problem could you please explain this to me.

 

All the best, Martyn.

[Christian]

Thank you for posting this complete build, I have just one question ? I cannot see from the photo of the nearly finished loco above exactly how close you have managed to get the brake shoes to the wheel rims. It's just that as all the brake rigging is cast there cannot be much in the way of any flexing and the fact that you are using Slaters wheels, I would think it must be very hard to get them very close together. I have used nickel silver 0.7mm rod in the past to spring the brake gear into place once the wheels are fitted. But surely it's near impossible to fit the wheels after the brake shoes are in place because of the wheel flanges and the way Slaters wheels are fitted If you get my drift . If there is a method of getting round this problem could you please explain this to me.

 

Hello Martyn,

 

Posted below is a close up of one of the brake shoes in relation to the wheel.

I have managed to get the shoe fairly close to the wheel whilst still allowing plenty of movement for the compensation to work, and some side play on the middle wheels. As you have said this also creates a problen trying to get the wheel off the axle and my solution to this was to shorted the square section of the exle ends, not by much maybe a couple of mm. This gives just enough room to tilt the wheel off the axle and slide the wheel up through the brakes.

 

[Scale7JB]

If only you were building in S7, you'd have loads of room between the flanges and the brake shoes...

 

JB.

[3 link]

Hello Martyn,

 

Posted below is a close up of one of the brake shoes in relation to the wheel.

I have managed to get the shoe fairly close to the wheel whilst still allowing plenty of movement for the compensation to work, and some side play on the middle wheels. As you have said this also creates a problen trying to get the wheel off the axle and my solution to this was to shorted the square section of the exle ends, not by much maybe a couple of mm. This gives just enough room to tilt the wheel off the axle and slide the wheel up through the brakes.

 

 

Hi Christian,

 

Thanks for the explanation, the tolerances between those wheels and shoes are amazingly close. I am not sure my banana fingers are up to the task !! I am just about ready to fit some cast brake gear to a jltrt 42xx, did you cut or part off on a lathe the square section ? And also did you have to cut down the retaining screw or are the threaded holes deep enough ?

 

If only you were building in S7, you'd have loads of room between the flanges and the brake shoes...

 

JB.

 

Ah I was waiting for Mr JB to come and promote S7, and all I will say in my defence is " I bet you S7 A3 wouldn't negotiate a 6' radius " ;)

 

Regards, Martyn.

[Scale7JB]

Ah I was waiting for Mr JB to come and promote S7, and all I will say in my defence is " I bet you S7 A3 wouldn't negotiate a 6' radius " ;)

 

That is a very fair point !!

 

JB.

 

 

 

[ozzyo]

If only you were building in S7, you'd have loads of room between the flanges and the brake shoes...

 

JB.

 

Hello JB.

 

the only bit that looks tight to the flange is the brake hanger, we can get away with turning the flange down by 0.5mm dia. but do not alter the thickness of the flange. That can give you a bit of a breathing space.

 

 

OzzyO.

[Scale7JB]

Hello JB.

 

the only bit that looks tight to the flange is the brake hanger, we can get away with turning the flange down by 0.5mm dia. but do not alter the thickness of the flange. That can give you a bit of a breathing space.

 

 

OzzyO.

 

I think there is actually someone that has used S7 profile wheels on a sprung/compensated 32mm gauge chassis, though I'm not too sure how well it worked.. In theory, there's no reason why it shouldn't... it works perfectly in 33mm gauge so why not 32.. but springing compensation would be a MUST..

 

JB.

 

 

 

[Christian]

I must say that all this talk of scale 7 has started to get me thinking, I suppose that as my attention and eye for detail improves the look of the flanges on finescale wheels starts to look a little out of place.

I don't have a huge collection of rolling stock maybe ten locos in various states of build and a few items of rolling stock. I certainly would no go to the length of upgrading my existing rolling stock to scale 7, but I am tempted with it for future builds.

As I have said before, I don't have a layout to run my stock on and I am not a member of any clubs, not that I know of any in my area, so it is not like I would have rolling stock that could not be used.

I also don't think I would use scale 7 wheels on diesel locos as you really don't see that much of the wheels, but on these steam locomotives which I am becoming increasingly interested in, I think they would benefit from the finer look of scale 7.

Needless to say there is a lot to think about.

 

Anyway back to the world of regular finescale and the continued progress on Spearmint.

 

Work has continued on the tender chassis, I have fitted the cast water scoop and associated linkages and moved on to the brakes. Whereas I am able to remove the wheels on the loco, with the fitting of all the brake gear on the tender and the close proximity of the wheels to the brake pull rods the wheels will have to be permantly attached. Up until now I have not given much thought to electrical pickups, but as the tender wheels would soon be permanantly fitted a decision would have to be made. I do not like to use any type of pickup that wipes the wheels, I have had bad experiences with the Slaters style of plunger pickups and the type with phospher bronze strips. Instead I usually prefer some form of live chassis, on my diesel rolling stock this is easy as you can make each bogie live so long as they are both insulated from the loco body. Obviously with the steam loco there are no bogies so the whole thing becomes live. This is not a problem until you start to couple up to rolling stock and then all sorts of problems can arise. Both the buffer heads and the couplings would need to be insulated to avoid his problem or rolling stock that does not ground to the track.

So I am going down the live chassis route where the loco picks up current from one side of the track and the tender picks up current from the other. The join between the loco and tender will need to be insulated. I am not to sure what to do about the couplings and buffers yet so any suggestions would be welcome.

As I am using Slaters wheels which are insulated on both sides, I shall have to make one side of the wheels live. This proceedure has been shown many times on this forum but basically four of the tender wheels have a small straight groove cut into the plastic between the brass hub and the steel wheel. A short section of fine brass wire is then soldered in place and filed flush resulting in a 'live' wheel.

The wheels can now be permantly fitted to the tender and the brake gear can be built up aound the wheels.

 

The follwing photos show where I am up to.

 

 

 

 

 

Next to build is the outer frames so that will be the task for next weekend and without any distractions from foolish Red Bull drivers in the Grand Prix!

[Scale7JB]

I must admit, I'm a huge fan of split axles myself... Can't fault them..

 

JB.

[Adrian]

I must say that all this talk of scale 7 has started to get me thinking, I suppose that as my attention and eye for detail improves the look of the flanges on finescale wheels starts to look a little out of place.

[snip]

I also don't think I would use scale 7 wheels on diesel locos as you really don't see that much of the wheels, but on these steam locomotives which I am becoming increasingly interested in, I think they would benefit from the finer look of scale 7.

Needless to say there is a lot to think about.

 

To be honest for me the attraction of Scale7 for me was not the wheel standards and appearance but rather the fact that it allows me to put the frames in the right place.

 

I started scratchbuilding an Ivatt 2 2-6-0 in 7mm finescale. I had to make all sorts of fudges to get it looking right because of the narrow frames for 32mm finescale. Having spent hours poring over photo's I was struggling because the model didn't have the same delicate nature of the prototype. It then struck me that because of the narrow frames the running plate had to be just over a couple of mm wider than the prototype. Which may not sound much but when the running plate is only 15.5mm wide (to scale) then it's a large percentage. More details with photo's on my website here.

 

Also if you are a GOG member have a look at the latest Guild Gazette, a couple of the loco build articles mention problems with narrow frames being restrictive on space. With article on the GCR 8K 2-8-0 the photo at the bottom of page 30 says it all for me. Notice how the firebox sits on top of the wheel splashers? This is because the splashers are too wide because they have to meet the dummy frames towards the front. In S7 with the correct width frames then the firebox could sit in between the splashers like the prototype.

 

I remember talking with Clarry Edwards about the live steamers he built. So that he could run on 32mm gauge he actually built his loco's to a slight smaller scale, something like 6.8mm to the foot, so that everything would remain in the correct proportion.

 

Anyway I'll get off my soapbox now - hopefully given you some food for thought!

 

Regards

 

Adrian

 

 

 

[ozzyo]

A bit to late in the build now, but I have built locos that pick on one side and are live to the body, and have the tender pick up from the other side but have the body neutral. Looking at the tender you could do it but you would have to undo some of your work.

 

On locos that I have done it starts with a brass tube of 5/32" in. dia. then you make some top hats to suit the Ex. dia. out of Tufnol then drill out the horn-blocks so that the Tufnol top hat will fit them. The axles are then isolated from the frames. You then solder your pick up wires to the tube and you have no wipers to worry about. You only need to do this to the loco or the tender not both. I find it best to do the tender. You will get shorts if you couple smokebox to smokebox though and vice versa. But I do fit the intermediate buffers between loco and tender.

If you would like me to drop some photos to you let me know, or if you would like me to post some on this thread again let me know.

 

OzzyO.

[3 link]

Hi OzzyO.,

 

I certainly would like to see some photos as pick ups are always a source of grief to most of us, whatever the gauge. Sorry to hijack the thread but I'm sure I will not be the only one who would be interested.

 

ATB, Martyn.

[Christian]

On locos that I have done it starts with a brass tube of 5/32" in. dia. then you make some top hats to suit the Ex. dia. out of Tufnol then drill out the horn-blocks so that the Tufnol top hat will fit them. The axles are then isolated from the frames. You then solder your pick up wires to the tube and you have no wipers to worry about. You only need to do this to the loco or the tender not both. I find it best to do the tender. You will get shorts if you couple smokebox to smokebox though and vice versa. But I do fit the intermediate buffers between loco and tender.

If you would like me to drop some photos to you let me know, or if you would like me to post some on this thread again let me know.

 

Sounds interesting, please share your photos with us.

[richard carr]

I think there is actually someone that has used S7 profile wheels on a sprung/compensated 32mm gauge chassis, though I'm not too sure how well it worked.. In theory, there's no reason why it shouldn't... it works perfectly in 33mm gauge so why not 32.. but springing compensation would be a MUST..

 

JB.

 

 

I have 8 locos that have scale 7 flanges that run on 32mm track albeit with tighter flange ways. All of them use compensation and run just fine even negotiating 4 foot 6 inch curves (the smaller tank engines do, the V2 won't).

 

As for converting them to scale 7 the steam locos with no valve gear would be relatively easy but those with valve gear would be difficult requiring a great deal of work to move each side out by 0.5 mm. All the wheels are already at scale 7 thickness so they just need to be re gauged. Diesels are very easy to convert it takes about 3 hours to do a Heljan Loco.

 

 

Richard

[ozzyo]

]

Sounds interesting, please share your photos with us.

 

 

Well here we go I've never done well with attachments, I dont think that I have put a photo on here yet. On the first two photos you can just make out the Tufnol insulation. This one was the first one that I did, made the mistake of removing all excise of the brass tube on the center axle, "now that is a NO NO' . In the last photo it shows the compensation unit that I use on most of my tenders. You would use two of them on an 8 wheeled tender. This is not set up for tender pick-up.

If you want more info let me know and I may start up a thread on it, the next time that I do one.

 

OzzyOattachment=attachment=41895:200 021b.jpg[][

 

OzzyO.

[3 link]

A bit to late in the build now, but I have built locos that pick on one side and are live to the body, and have the tender pick up from the other side but have the body neutral. Looking at the tender you could do it but you would have to undo some of your work.

 

On locos that I have done it starts with a brass tube of 5/32" in. dia. then you make some top hats to suit the Ex. dia. out of Tufnol then drill out the horn-blocks so that the Tufnol top hat will fit them. The axles are then isolated from the frames. You then solder your pick up wires to the tube and you have no wipers to worry about. You only need to do this to the loco or the tender not both. I find it best to do the tender. You will get shorts if you couple smokebox to smokebox though and vice versa. But I do fit the intermediate buffers between loco and tender.

If you would like me to drop some photos to you let me know, or if you would like me to post some on this thread again let me know.

 

OzzyO.

 

Hi OzzyO,

 

I understand your way of isolating the axles in what you explain above and also taking the current from the isolated brass tube, but how do you create the current from the wheel rim to the brass tube do you use the normal method of running a wire up the back of one of the wheel spokes between the rim and the axle.

 

ATB, Martyn. B)

[Christian]

Thank you Ozzy for sharing this with us it is certainly a different approach to electrical pick up and worth bearing in mind for future builds. Alas I have gone too far with Spearmint to start alterations and the temptation to use scale 7 would also be too great.

Nice photos by the way, you should share more of your work with us. I for one am very interested to see the rest of your builds.

 

Work has continued on Spearmints tender and the outer frames. The assembly has gone together very well as with the rest of the build with little problems to note appart from the buffers.

I have not fitted the buffer heads yet as they shall need some work. The problem is that the outer frames interfere with the holes for the buffer heads, a picture highlighting the problem follows below. I believe that someone else on this forum has experienced simular problems with a Finney tender for an A4 but I can't find the posts at the moment as they are burried deep within the depth of the forum pages. I would be curiuos to know how they got on.

The instructions suggest moving the holes inwards slightly so that they clear but by my calculations they would each move in over a millimetre which seems a bit extreme and surely would not look right. The other option would be to have non working buffers with out the springing and the rear shaft and nut assembly. Again this seems a bit extreme. I am not to sure what to do about this yet so shall leave the buffers off for a while until an appropriate solution can be found.

Anyway the progress can now best be shown in the following pictures.

 

 

 

 

 

 

The clearance between the wheels and the frames is very tight indeed and washers have been added to greatly limit the side play of the wheels so that they don't foul the frames. This surely would be challenging in scale 7.

 

On to the footplate construction next and hopefully photos to follow at the weekend.

[Scale7JB]

Christian, I seem to remember that on the Scale7 society website there is someone who made there own buffers as per the real thing where the spring was inside the buffer head itself leaving a buffer unit without the tail sticking out the back... This could well be an option..

 

JB.

[Adrian]

Christian, I seem to remember that on the Scale7 society website there is someone who made there own buffers as per the real thing where the spring was inside the buffer head itself leaving a buffer unit without the tail sticking out the back... This could well be an option..

 

JB.

 

That might be me you're referring to!! Full details and drawings are posted on my nascent website - http://www.cherryclan.com/scale7/workbench/sprungbuffers.html. It was for a Ivatt 2-6-0 where the back of the front buffer beam is exposed and I didn't want a 8BA or 10BA nut floating around in an exposed area. I'm not too sure how easy it'd be to modify for the A3 tender.

 

Adrian

 

 

 

 

[ozzyo]

Hi OzzyO,

 

I understand your way of isolating the axles in what you explain above and also taking the current from the isolated brass tube, but how do you create the current from the wheel rim to the brass tube do you use the normal method of running a wire up the back of one of the wheel spokes between the rim and the axle.

 

ATB, Martyn.

 

 

Hello Martyn & all,

 

if I am using Slater's wheels I set them up in my M/C vice on the milling M/C and using a 0.7mm slitting saw cut from the wheel rim to the brass boss in the center, then it's solder a wire to each then clean up. I use 145deg. solder and in and out quickly. Or I may use plungers on the loco.

 

On Harris wheel insulated on one side only no big deal.

 

As I said this was the first one that I did this way, this was with Harris wheels and one thing we did fined was a intermittent short on the loco when the wheel were at back dead center on the insulated side, the knuckle joint just touched the axle end. But only in reverse!!!!!!!!!! This didn't show up on 12 volts but did show up on DCC.

Hope that this helps.

 

OzzyO.

[ozzyo]

Thank you Ozzy for sharing this with us it is certainly a different approach to electrical pick up and worth bearing in mind for future builds. Alas I have gone too far with Spearmint to start alterations and the temptation to use scale 7 would also be too great.

Nice photos by the way, you should share more of your work with us. I for one am very interested to see the rest of your builds.

 

Work has continued on Spearmints tender and the outer frames. The assembly has gone together very well as with the rest of the build with little problems to note appart from the buffers.

I have not fitted the buffer heads yet as they shall need some work. The problem is that the outer frames interfere with the holes for the buffer heads, a picture highlighting the problem follows below. I believe that someone else on this forum has experienced simular problems with a Finney tender for an A4 but I can't find the posts at the moment as they are burried deep within the depth of the forum pages. I would be curiuos to know how they got on.

The instructions suggest moving the holes inwards slightly so that they clear but by my calculations they would each move in over a millimetre which seems a bit extreme and surely would not look right. The other option would be to have non working buffers with out the springing and the rear shaft and nut assembly. Again this seems a bit extreme. I am not to sure what to do about this yet so shall leave the buffers off for a while until an appropriate solution can be found.

Anyway the progress can now best be shown in the following pictures.

 

 

 

 

 

 

The clearance between the wheels and the frames is very tight indeed and washers have been added to greatly limit the side play of the wheels so that they don't foul the frames. This surely would be challenging in scale 7.

 

On to the footplate construction next and hopefully photos to follow at the weekend.

 

 

Hello Christian,

 

sorry but I seem to be high jacking your thread . If its a corridor tender just fit non working buffers and a drop head buckeye coupling (I think that J.L.T.R.T. do them). If it has a screw coupling then you may have two options that could work.

 

A] file one of the nut faces down until you can just see the tops of the internal thread, this side goes to the frames.

 

B] cross drill the shaft of the buffers about 0.7mm, I made a little jig to do this see photo,it also sets the length as well.

 

You may still have to move them in a bit as well but not as much as you would with a full nut.

 

OzzyO.

[Christian]

Thanks for the information Ozzy, I certainly have some ideas to think about.

I think the best approach may be to flatted one edge of the rear of the housing and the retaining nut, this and slight inwards movement may be acceptable.

[richard carr]

Christian

 

One thing you may not have realised about scale 7 is that the wheels in fine scale are too thick, Slaters driving wheels are typically 4mm thick, the correct thickness for an A3 driving wheel is 3.15 mm (RCTS greenbook specifies the wheel thickness for an A3) the same applies to tender wheels too, so although the inside face of the wheels are further apart the outside surface of scale seven wheels are only a tiny bit further apart than finescale ones.

 

Richard.

 

 

Thank you Ozzy for sharing this with us it is certainly a different approach to electrical pick up and worth bearing in mind for future builds. Alas I have gone too far with Spearmint to start alterations and the temptation to use scale 7 would also be too great.

Nice photos by the way, you should share more of your work with us. I for one am very interested to see the rest of your builds.

 

Work has continued on Spearmints tender and the outer frames. The assembly has gone together very well as with the rest of the build with little problems to note appart from the buffers.

I have not fitted the buffer heads yet as they shall need some work. The problem is that the outer frames interfere with the holes for the buffer heads, a picture highlighting the problem follows below. I believe that someone else on this forum has experienced simular problems with a Finney tender for an A4 but I can't find the posts at the moment as they are burried deep within the depth of the forum pages. I would be curiuos to know how they got on.

The instructions suggest moving the holes inwards slightly so that they clear but by my calculations they would each move in over a millimetre which seems a bit extreme and surely would not look right. The other option would be to have non working buffers with out the springing and the rear shaft and nut assembly. Again this seems a bit extreme. I am not to sure what to do about this yet so shall leave the buffers off for a while until an appropriate solution can be found.

Anyway the progress can now best be shown in the following pictures.

 

 

 

 

 

 

The clearance between the wheels and the frames is very tight indeed and washers have been added to greatly limit the side play of the wheels so that they don't foul the frames. This surely would be challenging in scale 7.

 

On to the footplate construction next and hopefully photos to follow at the weekend.

[Christian]

One thing you may not have realised about scale 7 is that the wheels in fine scale are too thick, Slaters driving wheels are typically 4mm thick, the correct thickness for an A3 driving wheel is 3.15 mm (RCTS greenbook specifies the wheel thickness for an A3) the same applies to tender wheels too, so although the inside face of the wheels are further apart the outside surface of scale seven wheels are only a tiny bit further apart than finescale ones.

 

Hello Richard

 

No, I did not know that scale 7 affectes the thickness of the wheel. There is much for me to think about regarding scale 7 but I am getting very tempted indeed.

 

[That might be me you're referring to!! Full details and drawings are posted on my nascent website - http://www.cherrycla...ungbuffers.html. It was for a Ivatt 2-6-0 where the back of the front buffer beam is exposed and I didn't want a 8BA or 10BA nut floating around in an exposed area. I'm not too sure how easy it'd be to modify for the A3 tender.

/quote]

 

Adrian,

 

Very interesting indeed. I have been studying your method on enclosed springs for buffer housing and trying to figure out if I can do the same for Finney buffers, it looks like I may be able to come up with something.

However I am missing one vital componant, a lathe. It's a tool that I would have liked but always been able to do with out. I purchased a small milling maching recently and it get used no end. I see you have put a lathe to good use on the std 4 build, but I don't know much about metal working lathes and their associated tool bits.

I shall have a think on how I could adapt the buffers without such a tool.

[Adrian]

However I am missing one vital componant, a lathe. It's a tool that I would have liked but always been able to do with out. I purchased a small milling maching recently and it get used no end. I see you have put a lathe to good use on the std 4 build, but I don't know much about metal working lathes and their associated tool bits.

I'm intrigued - why did you opt for a milling machine before a lathe? A milling machine is on my list of things I'd like to acquire but a lathe was higher priority. Most of the milling jobs I can think of could be done on a lathe with a vertical slide (the next item on my shopping list!) but it's probably harder to use a milling machine as a lathe. So what do you use the milling machine for? Perhaps I ought to start thinking a bit more about a milling machine as well.

Adrian