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Post by Deleted on Sept 27, 2011 19:15:51 GMT
Thanks John, I have done as you suggested, clack before Tee, I'll show it in a picture later....  Ok so I couldn't put it off any longer, it was time to drill the two No.30 holes ( I'd been pitting this off for obvious reasons) for the regulator body into the top of the boiler as shown in the picture. First hole was 5/32 forward from the dome ring with the next being another 1/4 after that. I sat the boiler on the mill bed, levelled it up, checked that it ran true down the length of the bed and the used a centre finder to check I was drilling perfectly central. Attachments:
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Post by Deleted on Sept 27, 2011 19:27:33 GMT
Next job was to transfer the two holes to the regulator body itself, I have to say setting the body in it's correct position was a real pig. The body screws onto the steam pipe which in turn is screwed on to the wet header flange, the trouble is you have to get the two threads involved in the correct position so that they both lock up tight together. This and the fact that your doing this while trying to hold the body through the small dome opening is no easy task. And the real pain is the fact that once the hole positions have been marked you have to take it all apart again to drill and tap the two 6BA holes, who said Model engineering is fun?....  The picture shows the body ready for fitting. Attachments:
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Post by Deleted on Sept 27, 2011 19:36:33 GMT
I then turned my attention to the regulator control rod. This is 5/32 stainless steel 12 7/8 long threaded 40T both ends. 2" from backhead end a 3/8 dia x3/16 brass collar is drifted onto the rod. Attachments:
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Post by Deleted on Sept 27, 2011 19:38:36 GMT
The assembly so far was then held in the machine vice while it was cross drilled to accept a 1/16 brass pin. Attachments:
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Post by Deleted on Sept 27, 2011 19:41:30 GMT
Next a return spring had to be made from 22swg bronze spring wire, an offcut of 5/32 rod was used for this in the lathe as shown. Attachments:
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Post by Deleted on Sept 27, 2011 19:43:47 GMT
Finished spring in position Attachments:
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Post by Deleted on Sept 27, 2011 19:48:07 GMT
I still had a few items to make before I could fit the regulator body, sliding valve, two swing arms and pins. Here the valve block made from copper is being machined to final size after first having a 1/8 slot cut using a suitable ball nose cutter. Attachments:
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Post by Deleted on Sept 27, 2011 19:51:25 GMT
The finished assembly now fitted in to the boiler, the two brass screws are temporary until I have made up some bronze ones, the holes still need counter sinking too. Attachments:
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Post by Deleted on Sept 27, 2011 19:54:58 GMT
I made up a temporary extension piece to help me connect the rod to the yoke on the regulator body, last thing I wanted to do now was drop the rod inside the boiler...lol Attachments:
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Post by Deleted on Sept 27, 2011 20:02:42 GMT
Last picture for tonight, with the regulator flange screwed in as tight as it would go( remembering to included a fibre washer) I placed a mark centrally 1/8 down from the top edge of the flange ready for drilling and tapping 6BA to fit the handle hinge later. Now a question guys, what's best for packing yarn here, PTFE or Graphite. I ask as stopping 80-90 psi from leaking through this point doesn't sound like an easy task to me, the fit between the control rod and it's bush are a good one though, slides nicely with no sideways movement..... Cheers Pete Attachments:
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Post by Shawki Shlemon on Sept 28, 2011 10:29:16 GMT
You are doing fine Pete , as for the packing , its a matter of choice, like everything there are positives and negatives , I have been using PTFE for many years , the negative is when cold it may leak particularly during hydro test but it seals OK when hot , to form the seal , tighten hard , loosen and nip . On the other hand the graphite yarn has been used for a long time successfully , your choice . ;D
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Post by Deleted on Sept 29, 2011 18:24:41 GMT
Thanks Shawki, PTFE it is then.... Ok today's update concerns more work on the boiler, first is the fire-door. This is a temp door, as you may remember I'm building this loco for both experience in locomotive workings and to learn how to steam. With this in mind naturally I don't want to spend years going into super detailing as I am with my own loco build 4472. So the plan is to get Lassie into steam ASAP, while steaming her I'll continue building FS, once she's completed and in steam I'll return to Lassie and rebuild her as a faithful miniature of the 'Great Northern' 4470. Anyway back to the firedoor , not wanting to go into too much detail and time with a Gresley flap type door ( assuming 4470 still had this after Thompson's rebuild) I've put together a simple door consisting of an oval disc in 1/16 steel silver soldered to another smaller disc from 1/8 steel that matches the profile of the firebox opening. A hinge was then made up and riveted to the door. Now on speaking to the boiler guys at my club I asked what they thought of me just soldering the hinge bracket to the firebox using cumsol instead of drilling and tapping for bronze bushes. My reasoning being that since both procedures involve soft solder and since it's below the waterline perhaps this would be ok for a temp door ( when I rebuild her I'll do it the proper way). The general opinion was there's no problem doing this and since the worst thing that could happen would be the door falling off I went ahead as can be seen here... Attachments:
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Post by Deleted on Sept 29, 2011 18:26:00 GMT
Another shot showing the door open Attachments:
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Post by Deleted on Sept 29, 2011 18:38:21 GMT
And now for another slight problem, well it could have been disastrous but luck was on my side. The blower hole was blocked and needed drilling through ( having first checked with John ( Baggo) that this was not the norm) . On close inspection it was obvious that during construction of the boiler and it's blower stay silver solder had got into the tube. The blower tube has been tapped 1/4x40T with the tube ID itself being 1/16 so first job was to make sure that any drilling was central. Attachments:
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Post by Deleted on Sept 29, 2011 18:41:59 GMT
To do this I turned up a 1/4x40T plug and centre bored it 1/16. Using a hand drill I first piloted the blocked tube with a smaller bit and then finished with the correct 1/16 size Attachments:
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Post by Deleted on Sept 29, 2011 18:47:58 GMT
Last picture for today, you can't really see it but the tube was cleared successfully, I did a quick test with compressed air and on blocking one end of the tube and placing a piece of paper over the dome hole a leak would have shown itself by disturbing the paper, I'm happy to report all seems well. Pete Attachments:
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Post by Deleted on Oct 9, 2011 12:22:38 GMT
First off apologies for lack of content lately, works been getting in the way... Lol Well managed to get a few things done, first was to finish the fixing of the regulator body to the boiler top. Not much involved here, countersunk the two 5BA holes and replaced the temporary brass screws with stainless steel. Attachments:
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Post by Deleted on Oct 9, 2011 12:29:54 GMT
Here is the oil feed pipe for the centre cylinder steam pipe. I've modified this from the drawing which had this joint under the smokebox which looked a little problematic if it ever leaked, at least here I can get to it without having to remove the boiler, It's not prototypical but it is practical. I still have to fit an inline oil check valve which is currently on back order with Blackgates along with the 1/8th copper pipe that I need to finish the blower jets. Attachments:
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Post by Deleted on Oct 9, 2011 12:36:52 GMT
Last picture, as you can see I have sprayed the backhead with BBQ paint ( resistant up to 650c) and fitted some of the fittings, both clack valves, blowdown valve, blower valve and injector valve. Only the axle/hand pump valve has pipework fitted, fittings left to do are the pressure gauge, water gauge and combined turret and whistle lever. Getting there... Pete Attachments:
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Post by Deleted on Nov 11, 2011 12:54:27 GMT
Afternoon everyone Had a small setback today so asking for some advice. I'm close to the stage of fitting the boiler for the last time and did one last run on compressed air before doing so. Running just on centre cylinder there was a crack sound which turned out to be one of the roller pins holding the left hand driving wheel to the axle just like the pin shown here securing one of the coupled wheels. It turned out that the pin has failed (split in half allowing the wheel to move a few degrees) so I'm asking the more experienced amongst us are roller pins the norm or is solid better. These pins were fitted by the original builder and I haven't found any reference yet in Curly's words regarding said pins, I'm not saying it's not there just that I haven't found it on the pages that I'd expect too. I now have the axle off the frames and the offending wheel separated from it which is a fairly straight forward task, I have some silver steel of the correct diameter so my question is, can I replace the pin with silver steel or should the pin always be of the roller type? All help/comments would be gratefully received. Regards Pete Attachments:
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