Greg
Involved Member
Posts: 84
|
Post by Greg on Nov 20, 2023 6:47:08 GMT
Hi, I'm thinking about building a 5" Ajax. Some wheel casting came up cheap, not ajax wheels, but I thought they might work. Unfortunately the crank pin offset is 1". Ajax is 1 1/8" so not really suitable unless I change the design. I could possibly use them if I reduced stroke. So I was wondering what they might be for. I'm in Aus so could possibly be an Aus loco. The person I bought them off didn’t know what they are for. The wheels have are 14 spoke. Casting overall size 4 3/4", so perhaps for a tyre OD of 4 3/8". Crank pin offset 1". Does anyone know of a 5" loco that has a crank pin offset of 1”? I have a couple of options: 1: Don’t use them or 2: Find a loco with valve motion and copy some of the valve gear design from that. Castings have got expensive especially posting to Aus which is why my hope is I can use these wheels. Thanks, for your thoughts, Greg.
|
|
|
Post by Nigel Bennett on Nov 20, 2023 13:11:49 GMT
You could perhaps turn up some 1/16" eccentric crankpins and restore your 1.1/8" stroke... but you'd need to be very careful at the assembly stage to make sure they're all the correct throw.
|
|
lesstoneuk
Part of the e-furniture
Retired Omnibus navigation & velocity adjustment technician
Posts: 373
|
Post by lesstoneuk on Nov 21, 2023 1:16:56 GMT
You'll have to do some maths to see if the final tractive effort will be much different. TE= 0.85 x BP x (half no of cylinders)x CD x CD x Stroke. Divide that by wheel diameter. The drop in power can be adjusted by increasing the bore(CD) but you won't have much to play with. Go for it, bargains like this don't come along that often.
|
|
|
Post by simon6200 on Nov 21, 2023 1:24:29 GMT
Easier than an eccentric crankpins would be to bore out the holes with the throw you want until the old hole has disappeared then make stepped crankpin. I have done this.
|
|
Greg
Involved Member
Posts: 84
|
Post by Greg on Nov 21, 2023 6:52:54 GMT
You could perhaps turn up some 1/16" eccentric crankpins and restore your 1.1/8" stroke... but you'd need to be very careful at the assembly stage to make sure they're all the correct throw. Thanks for the suggestion Nigel. Interesting idea. I wonder how it would go as they'd now be a slight twisting force on them.
|
|
Greg
Involved Member
Posts: 84
|
Post by Greg on Nov 21, 2023 6:56:33 GMT
You'll have to do some maths to see if the final tractive effort will be much different. TE= 0.85 x BP x (half no of cylinders)x CD x CD x Stroke. Divide that by wheel diameter. The drop in power can be adjusted by increasing the bore(CD) but you won't have much to play with. Go for it, bargains like this don't come along that often. Tractive effort will be ok with less stroke because majority of time would only be pulling one person. i picked an ajax because looks good to me, looks like a simpler build, not scale and a round top boiler, but not set on it. Also happy to tweak the motion if needed to suit a 2"stroke.
|
|
Greg
Involved Member
Posts: 84
|
Post by Greg on Nov 21, 2023 6:58:36 GMT
Easier than an eccentric crankpins would be to bore out the holes with the throw you want until the old hole has disappeared then make stepped crankpin. I have done this. Although the outside of the crankpin casting on the wheel would be part gone so would need to check this out. first step I think is machine a wheel and see exactly what I have to work with.
|
|
Greg
Involved Member
Posts: 84
|
Post by Greg on Nov 21, 2023 10:33:34 GMT
So I might be able to make them work. So looks like offset is 1 1/32". Now if I move pin out another 3/32" I'll have the 1 1/8" offset I need. Issue then is then pin is meant to be 5/16" (8mm) diameter and centre will 5mm from edge. So I could do a stepped pin. 6mm hole and 8mm out. So that gives 2mm of casting on the edge. Will that be strong enough and not crack? The only thing is it wouldn't look pretty because there would be no wheel casting under the outer edge of the pin. Perhaps I could build it out with a bit of weld to make it look prettier. A bit of extra work, and not as nice as using the correct wheel, but I'll save about $400 by not having to buy wheels.
|
|
mbrown
Elder Statesman
Posts: 1,720
|
Post by mbrown on Nov 21, 2023 11:30:45 GMT
Once the coupling rods are fitted, I suspect they are likely to overlap the wheel boss enough that the reduced size is not noticeable.
Malcolm
|
|
|
Post by ettingtonliam on Nov 21, 2023 14:55:27 GMT
Don't weld the wheel. Cast iron welding is for experts! (Apologises if you are an expert CI welder!)
If it was me doing the job, I'd stick to the shorter stroke, so no issues with the wheel castings, and fit thicker pistons to keep the end clearance in the cylinders the same. No need (IMHO) to alter the valve gear, or anything else.
|
|
|
Post by brucevoelkerding on Nov 21, 2023 15:01:52 GMT
I think trying to make and fit eccentric Crank Pins isn't worth the Trouble with regards to the Tractive Effort. Consider how easy any of the Models begin to slip. The Locomotive Weight is not there to use anywhere near the calculated Tractive Effort. As an industrial, free-lance Tank Locomotive, I wouldn't worry about the Stroke. I would build it at 1-1/32" Stroke. The only Changes you would need to make are - 1. a longer Piston Rod - but that is usually measured at Assembly anyway, 2. a wider Piston to reduce the dead Volume at each End of the Cylinder, 3. a shortened Return Crank. It looks like the Walschaert's Layout is "all square". In that case a simple Sketch will show you the new Length. Building it as above will always leave you the possibility of re-building it with the "correct" Wheels if they ever became available. You would then need to make new Return Arms. If you keep the Piston Rings to the Drawing Dimensions registered to the rear of the Piston, even the Pistons will be reuseable. I agree with Malcolm regarding the Coupling Rod Bosses hiding the Wheel Bosses. By the way, you may find this YouTube series interesting youtu.be/-hRJP4whHr8 . Bruce
|
|
Greg
Involved Member
Posts: 84
|
Post by Greg on Nov 22, 2023 8:31:38 GMT
Thanks all, very good advice. I need to remind myself, I decided on and Ajax it for a simple build, and it's not a scale loco so does not even need to be true to the drawings. It's just a bout doing what looks good. Bruce, thanks for the you tube suggestion. I had been watching them. Very good series for set up and good practice. I don't have a DRO on my mill, but reminded by these of how much easier life can be with one. Greg
|
|
dscott
Elder Statesman
Posts: 2,438
|
Post by dscott on Dec 27, 2023 6:17:09 GMT
I just realised that we have a set of these. SPRINKLED in the direction of Speedy and Jinty by the girls at Reeves although not suitable for either. BLACKGATES sell the proper ones for both models. With additional bigger balance weights suitable for a Nigel Gresley 01 Tango. We are cobbling one of these together the boiler is huge!!! Or an E1 LBSCR locomotive according to the Meskelyne drawing at 4' 6" and 14 spokes. He also being an early President at our Reading Society.
Lovely to see that THE PILE OF CASTINGS on Reeves Facebook page could once again lead to people getting the wrong castings AGAIN.
David and Lily.
|
|
VGC
Active Member
Designing a perfect new version of valve gear ;-)
Posts: 23
|
Post by VGC on Dec 27, 2023 16:15:54 GMT
The first thing I see is that there is no cross balancing for the opposite wheel. The second thing is an even number of spokes. Perhaps anywhere in the world there is such a loco, but my first impression always would be that of dilettantism. This is a children's Playmobil wheel in my opinion, not a wheel for a model of a loco. Perhaps a good thing for a poor beginner's stationary engine. Melt it into a suitable 3d printed sand mold :-) :-) :-)
|
|
|
Post by brucevoelkerding on Dec 28, 2023 12:31:29 GMT
I happen to have a copy of the Wheel Drawing T-5014-D, 5 Jul 1917, for the North Eastern Railway's T1 & T2 (and later annotated by LNER as Q-5 & Q-6). These Locomotives lasted into the 1960's. What is interesting is - 1. the same Wheel Casting is used for all 4 Axles (thinner Flanges were used on the Intermediate and Driving Wheel Tyres), 2. the same Counterweight Profile is used for each Wheel, 3. the Counterweight lies exactly across from the Crankpin Hub (there is no angular shift), 4. there is no mention where to machine to reduce Weight or cross-balance (that may be on a separate Drawing, but is not noted on this drawing), 5. the Casting has 14 Spokes (even number) laid out the same as the pictured Casting.
At first, I wondered if the Castings were for a 5" LBSC Netta, but they appear to be too small. On the Prototype - o 55.25" Tread OD o 13" Throw
|
|
|
Post by davewoo on Dec 28, 2023 16:31:45 GMT
I used to belong to a club that had several Ajax's owned by members, it wasn't too far from where Dick Simmonds shop had been at one time which probably accounts for their popularity locally. All of them seemed to go pretty well so I don't think that reducing the stroke by a small amount would make too much difference to the performance. They tend to wag their tail a bit when running and one was built or converted to an 0-4-2 which I always thought looked very good, a bit like a baby Bridget. As for the spokes and balance weights being incorrect it is a freelance engine after all! One of the Ajax's bore a very neat nameplate "Ajax" the others were unnamed until some wag produced some nameplates and one of the owners returned to his engine one day to find it was now called "Vim". Good luck if you do decide on the build. Dave
Perhaps I should explain that Vim and Ajax were household scouring powders widely advertised on TV in the UK in the 60's
|
|
Greg
Involved Member
Posts: 84
|
Post by Greg on Dec 29, 2023 3:08:42 GMT
The first thing I see is that there is no cross balancing for the opposite wheel. The second thing is an even number of spokes. Perhaps anywhere in the world there is such a loco, but my first impression always would be that of dilettantism. This is a children's Playmobil wheel in my opinion, not a wheel for a model of a loco. Perhaps a good thing for a poor beginner's stationary engine. Melt it into a suitable 3d printed sand mold :-) :-) :-) Thanks for the information, but no help at all, just I feel, a comment made to negatively critique the work done by someone, whose labour may have been for nothing more than to assist someone in making a locomotive, a "Plymobile" that's only purpose was probably to provide a additional of fulfilment and happiness to someone's life. Your comments do not encourage others to take on a lengthy endeavour, knowing that some are more focused on pointing out the flaws, than encouraging and supporting others. I feel it would take some effort to turn these piece of cast iron into a "children's playmobil", especially one that a child would want to play with. They're also clearly not suitable flywheel for a beginner's stationary engine. While these comments were no doubt made in jest, I feel the castings are not even suitable for a "dilettantism" effort at one of these things. So surprising suggestions. Perhaps an ugly paperweight would have been a better suggestion. Very suitable for that and no long hours of effort needed for it to work perfectly. If I had a furnace to melt them down, I wouldn't need to be making these casting work, I'd just make my own castings. :-) :-) :-) I did find a model loco that appears to have a wheel casting that's very similar in design to the ones I have.
|
|
|
Post by runner42 on Dec 29, 2023 5:47:10 GMT
Hi Greg,
I was suggesting that you view what E J Winter has to offer, but I realise that from the above photographs you have already done that. May I suggest that you machine the wheels to get a better feel of what problems you are likely to face in using them in the design.
Brian
|
|
Greg
Involved Member
Posts: 84
|
Post by Greg on Dec 29, 2023 7:30:05 GMT
Hi Brian, the wheels I bought were a set of eight too, but the casting looks a little different to the SMR Class 10 and I don't what the wheel size of it would be in scale.
At this stage I'm just thinking about my next project, I still need to finish my current one. So I haven't started machining the wheels them to a size. The wheels were a nice start, but I also like some material for the cylinders before making a decision. I was thinking I could machine them from solid block of cast iron. More work to machine, but should be a much cheaper way to go. If I could find a supplier of cast iron in Aus, then I might make a start. I've tried a couple of places for square cats iron, but no luck yet.
Greg
|
|
lesstoneuk
Part of the e-furniture
Retired Omnibus navigation & velocity adjustment technician
Posts: 373
|
Post by lesstoneuk on Dec 29, 2023 8:04:09 GMT
Surely you can use the motion designed for the loco you are building. The only difference is the piston stroke. There will be 1/8th of an inch extra clearance at each end of the cylinder. Either machine a wider piston or let in the piston covers. Drilling and fitting eccentric crank pins is complicating things too much.
|
|