Author Topic: Simplex  (Read 5840 times)

Offline Barneydog

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Simplex
« on: January 21, 2017, 03:23:29 PM »
Hi Guys,

Looks like my entire Simplex topic got lost in the recent migration because I probably started it after the 10th.
So to recap.....I have bought a part built Simplex. Frame is completely built. Cylinders are complete though not fitted. Motion work and valve gear was almost complete and fitted. I have now made the last of the Walcherts rods and am trying to do a basic setup to check everything is ok.
Everything looks good.....EXCEPT.... the slide valve. They are the correct size according to the plans but I believe the plan size is too wide. My valve ports are roughly 4mm wide on the input, 10mm wide on the exhaust with 4mm land between them. From one end to the other there is almost 1mm of one port uncovered and none of the other. If I mess about adjusting it further I would have less that half a mm each side. Martin Evans article does not explain the valve setup very well so the question is:-
How much of the ports should be visible at each end of the valve travel? My guess is that the whole of the relevant port should be uncovered otherwise what is the point of it being that width? I have removed one valve and replaced it with clear plastic so I can see the ports as I move the wheels. I have some markings showing a centre gap the width of the exhaust port, one inlet port and one dividing land giving a gap of about 18mm. This represents the hollow in the base of the slider to exhaust each port in turn. I have then marked each side at 4mm to give land to seal down to the cylinder valve face but leave a port fully open at each extent of valve travel. Is this correct or am i missing something?

Thanks

Julian

Offline Jo

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Re: Simplex
« Reply #1 on: January 21, 2017, 04:36:47 PM »
Martin Evans article does not explain the valve setup very well so the question is:-
How much of the ports should be visible at each end of the valve travel? My guess is that the whole of the relevant port should be uncovered otherwise what is the point of it being that width?

How much is uncovered depends on how far it is "notched back". You should look to set the valve so that the travel/amount uncovered is equal at either end.

Jo
Usus est optimum magister

Offline Barneydog

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Re: Simplex
« Reply #2 on: January 21, 2017, 04:51:28 PM »
Thanks Jo,
I understand it needs to be equal but how much should be uncovered? It needs some lead but 1mm sounds about right not nearly 4mm which leaves the port's virtually blocked.


Julian

Offline Barneydog

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Re: Simplex
« Reply #3 on: March 25, 2017, 10:15:57 PM »
Hi guys,
It's been a few weeks but had a beer moment............My simplex runs on air. It's slightly uneven because it has plenty of air leaks as roughly fitted together but it runs. I just wanted it to run so i can strip it back down and clean everything up. All rods,pins and linkages are now off and being cleaned, fettled and nickel plated. Axles have been dropped out the frames to be cleaned and painted. Frame is having the remaining balance bolts swapped for stainless metric ones and then frames
will be sprayed. Going to fit brakes as everything is refitted then it's boiler time!!

Video posted below. It's a bit jumpy to start with but improves....Photo bucket issue. Ignore the compressor in the background and you can hear the simplex.


Offline sbwhart

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Re: Simplex
« Reply #4 on: March 26, 2017, 07:34:50 AM »
Well done Julian

That looks OK to me.

Stew
A little bit of clearance never got in the way

Offline ChuckKey

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Re: Simplex
« Reply #5 on: March 26, 2017, 10:11:01 AM »
You never got a proper answer on your valve travel question. With Walschaerts valve gear the valve travel is determined by the design. It is not something you can set. All you can set is the valve position on its spindle. For an initial setting, put it in mid-gear and set for equal opening at each end. You may later find you want to make minor adjustments, but wait until it is in steam and doing work. You can then find the best compromise for a range of cut-off settings and balancing good forward gear with acceptable reverse gear running. 

Offline Barneydog

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Re: Simplex
« Reply #6 on: March 26, 2017, 07:05:11 PM »
Thanks Stuart

Thanks Chuck. I put the original slides on and set to midway so worked reasonably.

Thanks Julian

Offline Barneydog

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Re: Simplex
« Reply #7 on: April 05, 2017, 07:42:37 AM »
Hi guys,
I have completely stripped the frames for painting. All the valve running gear and con rods have been removed. All have been sanded, worked and fettled ready for surface treatment. As detailed on another of my posts on this forum I have gone through several processes but still come back to good old paint. All the bearing ends have been case hardened to protect them and give hopefully a decent life to them. Here I not a couple of problems. My nickel plating and later zinc plating systems could not cover the surfaces well enough on top of the case hardening. The higher carbon content showed through. Not wanting to waste too much time I hung all the parts on some long rods and with them suspended between two wheelies bins I primed and spray enameled them. They are all now sitting waiting to be refitted.
The wheels were dropped as complete axles and as there was not a lot wrong with them they were just cleaned of some of the paint on the rims and treads and then the centres of the wheels resprayed.
I am now in the process of building and fitting brakes to the centre and rear wheels. I have borrowed the super simplex articles from my local club and scanned them to use as guidance. I will take some pics as they progress.
The cylinders are off at the moment and will have all seals and gaskets fitted on their edit to the frames. I have got some round and some square graphite string for the seals. I am not sure about the pistons on this. Do i need to fit cast rings on them​ or can I use the square graphite string? The cylinders are cast iron. Is there any other material that would make good rings apart from CI?

Julian

Offline sbwhart

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Re: Simplex
« Reply #8 on: April 05, 2017, 03:54:40 PM »
Hi Julian

I fitted cast iron rings on mine as an alternative you could use pyre rings but you might have to make new pistons to suit graphite packing could be used but I don't think it would last as long as iron or ptfe. Whilst you have it striped down consider drilling and tapping into the valve chest and fitting a screwed plug to allow you to get oil in the cylinders when not running so they don't rust


Stew
A little bit of clearance never got in the way

Offline sbwhart

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Re: Simplex
« Reply #9 on: April 05, 2017, 05:04:30 PM »
Hi Julian

I fitted cast iron rings on mine as an alternative you could use ptfe  rings but you might have to make new pistons to suit graphite packing could be used but I don't think it would last as long as iron or ptfe. Whilst you have it striped down consider drilling and tapping into the valve chest and fitting a screwed plug to allow you to get oil in the cylinders when not running so they don't rust


Stew
A little bit of clearance never got in the way

Offline Barneydog

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Re: Simplex
« Reply #10 on: April 05, 2017, 10:59:28 PM »
Thanks Stuart. For the sake of thirty quid I will probably go with CI rings but first I need to check my spare plastics box cos i seem to remember buying a lump of PTFE as a might come in useful item. If i make PTFE rings will there be any expansion problems. I know i have a few lumps of stainless. Will we also decent rings?

Oil port already on the to do list.

Thanks

Julian

Offline Barneydog

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Re: Simplex
« Reply #11 on: April 08, 2017, 10:13:59 PM »
I started building some brakes today for the simplex. I drilled the frames for the support bolts and put a locknut on the inside. I then decided i ought to check the clearance needed for the boiler. This turned out to be only 3mm......Not very much!! As it's only a parking brake I have decided to only put brakes on the rear of the back wheels.

While I was checking the frames and the clearance for the boiler i remembered something the boiler inspector said last weekend at the club...."machine some off the top of the rear horns". I made a card cutout of the side of the firebox and held it inside the frames. Thank you Martin Evans......The boiler will not fit the frames. I removed the axles and wheels and took the frames to my mate Richards workshop and borrowed his S3 mill. This mill is bigger than mine so can hold the frames better. Machined the top to allow clearance for the boiler to sit in properly. Glad I sorted this before reassembling all the running gear otherwise it would have needed a complete strip down to machine the hornplates once I had found the boiler did not fit.

Julian

Offline Barneydog

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Re: Simplex
« Reply #12 on: September 24, 2017, 08:42:39 PM »
Hi Guys,
Been a while since I posted on this.

With a few issues about copper grades resolved and copper bought I have started building the boiler.
When I bought this part built loco it came with a piece of tube partly cut to form the boiler and all the plate cut, formed and marked for the holes and bushes. The tube was too short and had also been badly cut so it has been put to one side for a future project. I bought a new length of 4 3/4" 3mm thick copper. I cut it and fitted the front plate assuming it was correct.
Next job I checked the front firebox tube plate and found it wrongly sized. Checking the rear plate this was also wrong. I decided to cut some former plates from some 12mm steel I had acquired and reform the existing plates. I soldered the tubes into the front plate surprisingly easily and was well pleased with the job.

Next job was to form the wrapper for the firebox. This is when I realised the the plates were still the wrong size. I had made them better but had not corrected the size. I removed all the tubes from the plate and made new plates.

Once the tubes were soldered into the new plate I formed the wrapper. I made a rough wooden former for this.

This wrapper has been soldered to the firebox rear plate. It will be cleaned in the pickle later.

I now need to solder the front plate into the wrapper but not done yet.
In a sudden fit of common sense I decided to try the main tube and firebox in the frames and it does not fit!! The front plate I have fitted is about 4mm too big and has made it too wide to fit the frames.

Looking back I should have checked the existing plates better and done what I have now done....make my own.
This afternoon I made a new former for the front plate and backhead and made new plates. I then spent a very hot and sweaty hour or so removing the faulty plate.




All is in the pickle now for a new attack on it later this week.

Julian.
« Last Edit: September 24, 2017, 10:04:09 PM by Barneydog »

Offline Barneydog

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Re: Simplex
« Reply #13 on: September 24, 2017, 09:27:22 PM »
Hi,
Here's a better pic of the new firebox plates ad wrapper. Sorry last post had small pics. I have only just started with use.com so getting used to it. Not worked out how to get pics bigger so this one small aswell.

Julian


Edit....sorted pics :ROFL:
« Last Edit: September 24, 2017, 10:05:21 PM by Barneydog »

Offline Firebird

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Re: Simplex
« Reply #14 on: September 24, 2017, 10:15:30 PM »
Hi

A nice afternoons work :ThumbsUp:

Cheers

Rich