4303
Active Member
Posts: 44 
|
Post by 4303 on Feb 12, 2017 10:42:03 GMT
I've some concern that the crosshead detailed in the Shortland drawings might be problematical in as much as the slipper oilbox won't permit the connecting rod to articulate at the required angle (TDC) due to the rod oilbox fouling the crosshead oilbox. Works drawing 98682 (Feb '34) shows a cast steel crosshead. I've looked at 6106 and 4144 at Didcot and both have the earlier 'built-up welded' type which lasted until the end of steam on some locos. The various published photos are either too distant to tell or have the welded type. Does anyone have a picture of the cast steel type? They were common on the four cylinder 4-6-0s by the date of the works drawing and it's a feature I'd like to use but with firm back-up. We've all been at the track when Mr. Know-it-all rolls up with 'that's completely wrong you know' and it's nice to be able get the Spitfire airborne to shoot him down!
Also, when a later crosshead with 'onboard' oilboxes was used were the oilboxes on the top guide bar omitted? 4144 (partially dismantled at the time of my visit) had only the (front) piston-rod oilbox fitted. Later engines like the Granges and Manors seem only to have the piston-rod oilbox.
Progress on mine continues despite the cold weather. I've managed to recover a poorly machined set of the later webbed type driving and coupled wheels (each diameter and crank throw differed - really!) but free is good. They are 0.020" undersize now with the crankpin holes jig drilled correctly and they turn without binding with the coupling rods on - my ancient quartering jig still works. A professionally made boiler (1986 but never used) has come my way which will speed things up but I've also my boiler kit to make (some day).
Looking forward to hearing from others in the group.
|
|
|
|
Post by Rex Hanman on Feb 12, 2017 21:18:05 GMT
Is this the welded type? I suspect it is. www.modeleng.org/images/prairie/The photos I have look to be the same. To be honest I'm not sure if I would know the difference. Glad to see someone is making progress. I've just about got my workshop back together so fingers crossed! |
|
|
|
Post by fostergp6nhp on Feb 13, 2017 22:50:26 GMT
That's the welded type.
|
|
|
|
Post by bmwbob on Feb 21, 2017 20:45:04 GMT
I had the same problem with the oil box fouling on the cross head slot.. My fix was to reduce the height of the oiler so that it would clear. Probably not the correct solution for the purist but there is so much detail to get your head around I needed a workable solution. On 1st Feb 2017 I ran my chassis on air successfully, I had a major concern wether I had fixed the eccentrics in the correct place given they were keyed on, thank goodness they were OK. Started mine in 2008, 8 odd years ago.. Buiilt a Ken Swan 71/4 Wren in between. I estimate to be getting on with the plate work in a couple of months. Boiler done and tested.. Could be done before end 2018 unless I get diverted on something else.....
|
|
|
|
Post by ducatibob on Aug 5, 2017 22:11:48 GMT
Hi Chaps,
It would be nice to know how many of us are building prairies... I have for the last two months manufacturing brake parts... Should have know the devil is in the detail and what detail there is, another misjudgement on my part yet again... Still another month or two and I will have the brakes done. Made 32 bronze bushes today..... I am making 5102 does anyone know of the correct colours for this engine... A bit previous but thought i had better start thinking about colours in plenty of time..
Bob
|
|
dscott
Elder Statesman
Posts: 2,437
|
Post by dscott on Aug 6, 2017 23:49:14 GMT
Two of us are building them within strolling distance in Reading which may be a first!!
5105 for me, and too many distractions via Wives and Daughter. Houses. Gardens and building
a new workshop.
And 3 months in deepest China confined to eating Chinese food at every meal!!!
Came back with a sketch book of distractions and way too many photos!
David and Lily.
|
|
4303
Active Member
Posts: 44
|
Post by 4303 on Aug 15, 2017 10:44:33 GMT
A short follow-up on the matter of cast steel crossheads. I have located photographs of two 2-8-2T rebuilds and they both have the cast steel type. I have also located one large prairie and one Hall sporting this crosshead. Presumably they were shown on the 1934 large prairie works drawing as they were the current type in production.
|
|
galatea
Member
Always willing to learn!
Posts: 1
|
Post by galatea on Aug 25, 2017 20:51:10 GMT
A short follow-up on the matter of cast steel crossheads. I have located photographs of two 2-8-2T rebuilds and they both have the cast steel type. I have also located one large prairie and one Hall sporting this crosshead. Presumably they were shown on the 1934 large prairie works drawing as they were the current type in production. Hi All, I am looking to obtain the 5" gauge drawings of the Prairie? Would anyone have a set they would like to sell? |
|
Lisa
Statesman
Posts: 806 
|
Post by Lisa on Sept 11, 2017 8:09:39 GMT
Hi galatea, you can get them from reeves' site easy enough: www.ajreeves.com/2966.htmlFor that matter, it looks like you could just about build it off the pictures of the drawings there. |
|
|
|
Post by Laurie_B on Sept 15, 2017 20:49:18 GMT
I used some of the cast crossheads from the Polly Model Engineering 'Practical Scale'range. I also noticed on a few full size locos that the slide bars are attached to the motion brackets with two bolts per bar,and not the four as shown on the drawings.  , Work in progress. |
|
|
|
Post by Rex Hanman on Sept 15, 2017 21:31:39 GMT
That looks rather nice!  |
|
4303
Active Member
Posts: 44
|
Post by 4303 on Sept 16, 2017 8:40:35 GMT
Yes, the workmanship looks very good. I tried a pair of the Polly crossheads but realised, on inspection, that they are generic rather than specific. Also they are cast in an undefined grade of stainless steel which was too hard to machine - chilled?. I looked up annealing stainless on-line but without knowing what the material actually was it was difficult to know what to do with it. I fabricated some of the later cast steel type in the hope that they would be interestingly different and, more hopefully, prototypical. Free-cutting MS comes up with a nice shine but is probably not prototypical! The late Peter Rich provided some notes on the various types of crosshead on GWR locos as well as surface finish with dates but the information might not apply to mixed traffic engines.
|
|
|
|
Post by Laurie_B on Sept 16, 2017 10:07:49 GMT
Cheers gents! The Polly crossheads are more typical than prototypical;they compare fairly well with some of Peter Rich's drawings that I have. At least the dimension between the slide bars is correct. I've tried to avoid too shiny a look,preferring a drawfiled finish rather than the polished look seen on some models. Perhaps this view of 4150 taken at Bewdley a while ago might be helpful.  |
|
|
|
Post by highlandrailwayman on Aug 7, 2018 21:11:20 GMT
Two of us are building them within strolling distance in Reading which may be a first!! 5105 for me, and too many distractions via Wives and Daughter. Houses. Gardens and building a new workshop. And 3 months in deepest China confined to eating Chinese food at every meal!!! Came back with a sketch book of distractions and way too many photos! David and Lily. Dave Make that three in reading!!! I’ve not started yet but a set of drawings will be a gift from Santa in a few months time!!! |
|
dscott
Elder Statesman
Posts: 2,437
|
Post by dscott on Aug 7, 2018 22:43:05 GMT
I know someone with a joggle frame tool and he will be using it on the second set of frames
as soon as I (sorry he) gets a press organised!!
It is only complicated if you read all the sheets in one sitting!!!
Yes you heard correctly 2 or two of them. Yes some of the settings and formers and
machining sequences makes it easier!
David.
|
|
