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Post by Deleted on Feb 13, 2011 15:10:25 GMT
Pic159 Outside view showing brake assembly for the second axle Attachments:
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Post by Deleted on Feb 13, 2011 15:19:00 GMT
Pic160 Final picture for today shows inside view of the last axle. I can confirm that there is indeed an error for the third brake hanger as mentioned by others regarding "drawing errors" before me. It's nothing big just needs some metal removing from the back edge of that particular brake hanger to allow enough clearance for the shoe to fit between the hanger and wheel without fouling against the rear stay. Next job will be the brake beams followed by the coupling rods. I need the chassis at it's correct riding height first but I want to finish the brake stage first so will just use blocks to raise the chassis for now. More soon Pete Attachments:
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Post by Deleted on Feb 13, 2011 15:39:49 GMT
Pic155 On to the brake shoes, in the picture are the laser cut shoes from Model engineers laser , having now used these I think it may have been quicker to machine from solid. Pete I found the same syndrome: I dumped the cast iron versions and made some from solid. Much nicer! JB |
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Post by Deleted on Feb 15, 2011 23:14:24 GMT
Pic161 Continuing with the brakes here we have the last laser cut part from Malcolm's brake hanger kit. This is the front brake beam, if you look closely you'll spot the scribed lines across the end tabs. I decided to remove these as the material thickness was not thick enough to turn the tabs to the required 5/32 diameter. Attachments:
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Post by Deleted on Feb 15, 2011 23:24:23 GMT
Pic162 To replace the removed tabs I first turned up the two parts needed. These started as 1/4" BMS bar of which the beam has a 1/16 collar between the beam plate and the 5/32 coupling rod shaft. Since I planned to cut a 1/8th slot through the 1/4" section I increased it's depth to 1/4" to give more area for brazing and thus stronger, I doubt anyone would notice but if they do, hey who's loco is it anyway:) In the picture the finished shaft is being held in a jig for machining, using a suitable piece of BMS I drilled a No.22 hole for the 5/32 shaft the fit into. Having cut a slot in the end of the BMS it was easy two hold the shaft both tight and upright for machining. Attachments:
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Post by Deleted on Feb 15, 2011 23:27:47 GMT
Pic163 I forgot to take a picture of the parts before brazing but here is the finished beam fitted having had both the two No.30 holes drilled for the connecting rods to the brake shaft and the cross drilled holes for 1/16th spilt pins. Attachments:
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Post by Deleted on Feb 15, 2011 23:33:03 GMT
Pic164 The two coupling rod pins for the front axle were a similar exercise to the brake shoe pins but have 7BA threaded ends and a small 1/16 spigot on the end. The washers are commercial items, about time I found something already made to use , so much time spent on making things with little to show for it... lol Attachments:
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Post by Deleted on Feb 15, 2011 23:35:45 GMT
Pic165 Front brake beam and pin in place, I still need to make the nuts for the pins but I'll do those together once I've finished the rest of the pins and beams. More soon guys..  Pete Attachments:
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Post by Deleted on Feb 17, 2011 22:12:10 GMT
Pic166 Evening all Just a few pictures to bring up to date the brake pins and beams, this is the pin components having been silver soldered together before final machining and polishing. Attachments:
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Post by Deleted on Feb 17, 2011 22:14:05 GMT
Pic167 The third and fourth axles brake beams/pins fitted. Attachments:
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Post by Deleted on Feb 17, 2011 22:21:28 GMT
Pic168 Close up of the fourth axle brake beam. The beams are made up from three parts, two ends with the slots and the central BMS bar that fitted into predrilled holes in the end pieces. A jig was made up with 4" centres to hold the parts together for brazing. Tomorrow I'll start on the coupling rods which I have to admit I'm looking forward to, oh and I must do the 7BA nuts to hold it all together... Pete Attachments:
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Post by Deleted on Feb 18, 2011 20:05:18 GMT
Pic169 Evening all Today I concentrated on the brake coupling rods, nothing much to these other than lengths of 1/4x1/16 BMS bar with a No.30 hole drilled each end and then rounded off. The distance between the holes is critical and the chassis needs to be at it's right height before measuring the distance between pins. So first the chassis was raised on blocks to achieve this, next all brake blocks were clamped tightly against the wheels. It was then a simple job of measuring each distance between the pins and then making the coupling rods up as pairs to fit. Attachments:
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Post by Deleted on Feb 18, 2011 20:16:15 GMT
Pic170 Top view, washers are used to achieve the necessary clearance from the wheels as to Don's words and music. I'm pleased with the end result, all four wheels lock when the front brake beam is pulled so I think the brakes will work as they are supposed to (although I have no intention of using them other than to use the handbrake) and the rods all line up nicely. Next job will be the brake shaft and it's supporting trunions, followed by all the handbrake operating system. Shouldn't take to long, i hope ... Lol Pete Attachments:
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Post by Deleted on Feb 21, 2011 21:48:37 GMT
Pic171 Good day gents Today I have details of the brake shaft construction, this one item has taken me two days. So much work for a relatively small yet important part of the tenders braking system. The picture shows the start of machining on the shaft itself. It starts life as a 6" piece of 1/2" BMS ( centre drilled) which has a 1/4 diameter spigot to 5/16 depth machined on both ends. With the top slide then set at 4 degrees a section is machined to 7/16 up to the first collar( using a round nose tool) the first collar is 3/32 at 1/2 diameter . A cut is then made back to 7/16 for 5/32, leave another collar at 1/2 for 3/32 and back down to 7/16 until reaching the first brake leg collar. A 1/4 section is left here then back at 1/2 and then the tool cuts again at 7/16 for the middle section. The shaft is then reversed in the jaws and the process repeated for the other side. Hope that's clear, took me a while to work it out and Don said it better than me. To explain a little the four 3/32 collars are for the small brackets that attach to the front pull rods, the 1/4 sections are for the two large legs that attach to both the handbrake system and the two vacuum cylinders. Attachments:
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Post by Deleted on Feb 21, 2011 21:54:19 GMT
Pic172 The turning part completed shown against the drawing. Now a question looking at the four outer collars I've read the drawing as each one having a pull rod bracket attached, at least that's how I read the drawing as you can see line on them to show this. Although a photo I have just shows one bracket each side, thus between the collars although I can not see any collars in the photo. No big deal but I wonder which is right for FS, perhaps these things were made differently from different sheds? Attachments:
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Post by Deleted on Feb 21, 2011 21:55:34 GMT
Pic173 The two legs being drilled together before profiling. Attachments:
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Post by Deleted on Feb 21, 2011 21:58:31 GMT
Pic174 Now profiled to shape the next stage is to reduce the width except for the part that meets the shaft. The tongue at the far end will be removed once finished. Attachments:
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Post by Deleted on Feb 21, 2011 22:02:13 GMT
Pic175 On to the small pull rod brackets, holes drilled first as with the legs and then held together for machining. The alloy bush is just there to hold inline as once finished the tongue here will also be removed as with the legs. Attachments:
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Post by Deleted on Feb 21, 2011 22:04:53 GMT
Pic176 The small brackets held together with 1/8 BMS that has had a 5BA thread cut to unable a holding jig to be made ready for silver soldering to the shaft. Attachments:
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Post by Deleted on Feb 21, 2011 22:07:15 GMT
Pic177 And now the legs in a similar holding jig prior to also being silver soldered in place at 90 degrees to the rod brackets. Attachments:
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