Author Topic: Burrell Single Crank Compound Traction Engines - 4" Scale  (Read 49388 times)

Offline Kim

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #225 on: January 27, 2020, 05:42:33 AM »
Can you give a few more details on how you went about it please?

Later this week I hope to have a go at forming the front plate with it's smaller corner radius. When I do so I'll take more pictures and create a post that tries to explain the process in more detail.
Andrew

I'm looking forward to seeing this too!  :popcorn:
Kim

Offline Steamer5

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #226 on: January 27, 2020, 07:50:50 AM »
Hi Andrew,
 Thanks, looking forward to it! No pressure.

The stretchers on the Garratt, full size, were all formed & itís a stumbling block on making the model ones...mark 1 & 2 are lying under the bench, working on Mark 3 b!


Cheers Kerrin
Get excited and make something!

Offline jadge

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #227 on: February 01, 2020, 07:38:11 PM »
I've had a go at hot forming the front plate, and as promised here are more details of the process. These are the mallets used, a commercial copper one and a home made rough 'n' ready wooden one:



First the blank (about 10.5" by 8.5" by 3mm thick) is clamped to a former machined from hot rolled steel. The blank is aligned using scribed lines representing the fold lines. Some of the lines can just be seen bottom centre:



The finished flange is 3/4" deep and the internal radius on the corner is 3/4". Based on previous experiments I left the straight parts of the unfolded flange at 7/8" while on the corners I guillotined them undersize at 5/8", in the expectation that the flange would grow significantly as the fold was formed. Heating was with a cutting head and oxy-acetylene bottles. Here's the result after four passes bending a little at each pass, using only the wooden mallet:



On the straight flanges only the bend area was heated to red/orange. On the corners, after the first pass, the whole depth of the flange was heated. At each pass forming on the curves started at the top, by the bend, and worked down. If any hint of a kink appeared it was reheated and knocked into line before moving on. Bottom centre a potential kink can just be seen emerging. After the passes shown I did another couple with the wooden mallet heating the full depth of the flange all the way round. On the first pass I concentrated on the bend area, ensuring it was tight to the former. Second pass knocked the rest of the flange down to the former. The whole caboodle was then turned over. Another pass with the wooden mallet ensured the flange was tight on the former. A final pass with the copper mallet concentrated on the side flanges as these need to be very close and flat to ensure that the finished plate slips between the hornplates on the engine without needing much, if any, adjustment. Here's a close up of a straight flange:



And one of the corners:



Although the corner looks a bit rough, even at the lowest point it is nearly an inch deep. After cooling the former under a water butt the front plate slide off with a little persuasion from a large screwdriver and a nylon mallet. The next job was to machine the flange to depth, as measured with a ruler. No need for special precision here:



After cleaning up with wire brushes in the drill and emery cloth here's the inside of the plate:



And the outside:



The flange slipped nicely between the hornplates after a few strokes with a file on each of the side flanges. The next jobs are to drill fixing holes in the flanges, bring the bottom edge to shape (hacksaw and files) and machine a slot in the plate (CNC mill) for the drive rod to the water pump.

Andrew

Offline Jasonb

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #228 on: February 01, 2020, 07:49:57 PM »
Came out well and the plate looks to have stayed flat despite not using a top plate to keep it down on the former  :)

Offline Kim

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #229 on: February 02, 2020, 02:14:05 AM »
That's really nice Andrew!

And I guess by using a steel former you didn't have to unclamp the part to heat it up.  When using a wood former, it seems pretty important to be able to remove the part for annealing.

In your case, with the steel, were you hammering at it while it was red-hot?  Or were you only annealing the steel and then pounding away at it?

Nice pictures!  Really like your explanation!
Thanks,
Kim

Offline Steamer5

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #230 on: February 02, 2020, 04:30:32 AM »
Hi Andrew,
 Many thanks for taking the time to show this!  The plate came out very nice. And to get it so a couple of file strokes get it to fit, shows great skills!
I would think if thatís the case then it ......famous last words coming up.....then it should be quite possible to to form stretches such that a small machining allowance could be allowed for so that they could all end up the same width, read 7 plates!

Cheers Kerrin
Get excited and make something!

Offline jadge

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #231 on: February 02, 2020, 12:17:07 PM »
The plate was hammered when red hot. When the steel is red/orange hot it's very easy to bend. Could do it with fingers; if they were asbestos! The wooden mallet works well, but the slightest hesitation when hammering results in it smoking. If the ends of the mallet get too burnt I'll slice a bit off with the bandsaw, or ultimately make a new head. Since the metal moves so easily when hot a top plate isn't needed.

I've got one more spectacle plate and front plate to make, and then on to flanging the tender sides. But that will need some substantial machining to make the former. Good job I've got a fair selection of hot rolled steel.

There are a couple of other parts I may need to hot form. On the pictures I have of full size engines one has a tray across the bottom of the cylinder to catch oil from the piston rods, and  the other doesn't. I'm told they were manufacturer fit, but were optional. Originally they were cast, but I can either CNC mill or form one from sheet and weld on the mounting lugs, which might be quicker. I'm also looking at oilers for the rear axle and second shaft tubes as nowt is detailed on the drawings. The full size engines had wick feed oilers mounted high up on the hornplates and copper pipes down to the tubes. The oilers are simple; I'll simply knock out another batch similar to those on the slidebars. Plain brackets are simple, but one bracket is actually a small shelf which carries oil cans and the like as well as the oiler. It would be a doodle to make one using the folder for the straight bends and hot forming the flange around the sides. Of course if I make one then I'd also need to make a miniature oil can.  :)

Andrew

Offline jadge

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #232 on: February 18, 2020, 09:12:40 PM »
In idle moments I have been sketching out the arrangement for the regulator and 'starting' valve controls on my traction engines, based on pictures of full size engines. Here's the CAD model so far:



I started by making what I call the spectacle plate rod bushing, which is a casting on the full size engines. On the drawings it is shown as a flat plate with single slot for the regulator rod. There is no 'starting' valve detailed. Blanks were milled from hot rolled steel on the Bridgeport and the holes drilled. The rest of the milling was done on the CNC mill. I'm quite pleased with the finish which is as it came off the mills, no finishing or deburring (other than chamfering the holes):



And here it is in place on the spectacle plate complete with home made BSF nuts and bolts. Note that I've CNC milled the spectacle plate to clear the connecting rod and the as yet unmade valve rods. The cutout is according to my CAD model, the official drawing is nonsense.



Not sure what the next job will be, especially as I'm getting bogged down with glider inspections, made more difficult this year by new EU regulations. But I'm itching to get going on machining the cylinder castings.

Andrew

Offline Kim

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #233 on: February 19, 2020, 02:39:21 AM »
... I'm getting bogged down with glider inspections, made more difficult this year by new EU regulations.

So, why are the EU regulations affecting you now?  I thought the UK was out of the EU?  Or is that only 'eventually'?

Nice work on the Spectacle Plate :)  I can see why you call it that!
Kim

Offline Jasonb

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #234 on: February 19, 2020, 07:40:36 AM »
Does something else go into the middle hole as there looks to be a lot of detail for just saving some iron?

Monocle plate may be a better name on your engine as it only has the one large cut out

Offline jadge

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #235 on: February 19, 2020, 10:37:02 AM »
So, why are the EU regulations affecting you now?  I thought the UK was out of the EU?  Or is that only 'eventually'?

That's the theory, but not the reality.  :(

The current problem is SDMP aka self-declared maintenance program. Sounds innocuous but has big legal implications. It essentially means that the aircraft owner is now legally responsible for creating, and possibly implementing, the maintenance, which the inspector then signs off, or not if he isn't happy. It means new forms for a start. Most owners are clueless about the maintenance so the creation of the program falls on the inspector, even though the owner signs to take legal responsibility. In theory the owner can decide what maintenance to do and what not. There are some limitations, for instance airworthiness directives are mandatory, no ifs and buts. However, manufacturer directives are open to discussion. In particular in the UK we ignore the manufacturer recommendation to replace the seat harness every 12 years; we put it on condition, ie, assess the condition each year and replace if needed. One also needs an EU approved aircraft logbook, which takes a long time to fill in with all the ADs, repetitive inspections and one off mods. It sort of make sense as everything is collated in the logbook rather than being spread across various files. But the first time round it's a lot of work. Next year we've got sailplane pilot licences coming in, which will take away some freedoms.

At least when I potter in the workshop no-one tells me what I can and can't do and I don't need to register the machine tools or have a licence; well not yet anyway.

Andrew

Offline jadge

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #236 on: February 19, 2020, 10:40:46 AM »
Does something else go into the middle hole as there looks to be a lot of detail for just saving some iron?

Yep, as shown in the CAD model the eccentric rods will also pass through the cutout. There are also two round holes on the left side for the governor belt. There are placeholders in the CAD model, but since I don't know exactly where they need to be I haven't machined them yet. Dunno if that would make it bifocal or varifocal.

Andrew

Offline Jasonb

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #237 on: February 19, 2020, 01:07:21 PM »
Crossed wires, I was enquiring about the rod bracket. The rectangular recess and central hole and the slot between holes on the rear side look like they may serve a purpose.

Offline jadge

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #238 on: February 19, 2020, 03:18:29 PM »
The rectangular recess and central hole and the slot between holes on the rear side look like they may serve a purpose.
I don't know. I have pictures of three full size engines and all have the same features, that look as if they are as cast and just painted. It may be a way of saving metal, and weight, important when engines were taxed according to weight. I'll ask the question on TT and see what response I get.

Andrew