Author Topic: Coles C-611  (Read 16528 times)

Offline Jo

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Re: Coles C-611
« Reply #75 on: May 12, 2021, 11:53:51 AM »
Thanks Guys,

And don't do what I did and secure the drive dog to the wrong side of the drive pin  :Doh:. It took me a second to realise what I had done and it was the clue I was tired and it was best to walk away and come back another day.

Jo
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Online Twizseven

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Re: Coles C-611
« Reply #76 on: May 12, 2021, 02:18:59 PM »
Looking good Jo.  Its nice to see your reasoning for each step you take.

Colin

Offline RReid

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Re: Coles C-611
« Reply #77 on: May 12, 2021, 02:49:30 PM »
The "hows" in this thread are so valuable, but the "whys" are even more so. Thank you Jo.
Regards,
Ron

Offline Jo

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Re: Coles C-611
« Reply #78 on: May 12, 2021, 03:35:32 PM »
Thanks Guys, it is useful to beginners (and often the not so beginners) to explain the basics.

I left the steam chest a couple of days ago so it is time to just finish those off. The steam chest has had its top and bottom skimmed. Which is boring so no pics. I have not decided on the positioning of the rod relative to the base yet so I also skimmed the valve square and measured its height  :thinking:

While I think about that it is time to do the top cover: This is a nice thin piece of cast iron which needs to be turned to leave the existing boss in the centre.. first we need to be able to centre on the boss. You can if you want put a centre pop in the middle of the boss and try to mount the cover in the four jaw chuck but this is how I do it:

File the outside of the boss nearly round such you can hold it in a flexible collet that does not particularly care about roundness  like an ER-32  ::)



Hold cover in your flexible collet holder from the tailstock and tighten four jaws of the chuck round it:



Loosen off collet and remove, then use same ER32 holder to push against face of casting to check square and fully tighten jaws on chuck.



As we are a wimp next drill the centre of the boss with a centre drill for a rotating centre



and use the groove in the centre drill to let your lathe tool face the boss:



with rotating centre in place ,turn the boss to a known diameter which you have a collet for:



Take a shallow cut across the face to see actually how square it is mounted in the chuck:



Not bad  :thinking: An extra skim:



Lets stand back and look at those remaining marks: I probably will need to go a lot deeper to remove them so I will call it a day there. Time to do the other side: Remember we turned it to fit into a collet:



It makes life so much easier to turn the surface flat if you do. This is with a 0.3mm skim off the surface leaving a 4mm thick cover:



I now can consider what to do with the bits associated with the steam chest:



The questions to ask are:

1, What height should the centre of the valve spindle be?

2, Is there enough space inside the steam chest for the valve to travel up and down?

3, How am I going to do the valve gland so that it matches the main gland?

4, What diameter pipe should I use for the steam inlet, what would be an appropriate thread and do I already have an adapter so I can connect my compressor to it to test the engine.

All interesting questions that I am  going to find an answer to  :)

Jo
« Last Edit: July 28, 2021, 02:59:34 PM by Jo »
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Offline Roger B

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Re: Coles C-611
« Reply #79 on: May 12, 2021, 06:26:21 PM »
 :ThumbsUp:  :ThumbsUp:  :wine1: (or is Thursday wine day?)
Best regards

Roger

Offline Jo

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Re: Coles C-611
« Reply #80 on: May 12, 2021, 08:08:10 PM »
Thank you Roger  :)

:wine1: (or is Thursday wine day?)

It depends on what's for dinner - tonight was Pizza so that required Beer, tomorrow is delivered 1 Curry :P so that will also require  :DrinkPint:    or  :DrinkPint:  :DrinkPint:

Jo

1. Takeaway has changed to "Delivered" due to Covid  :naughty:
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Offline steam guy willy

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Re: Coles C-611
« Reply #81 on: May 13, 2021, 12:39:11 AM »
Hi Jo , I like that mirror finish on the crank webs !! still following along :ThumbsUp: :ThumbsUp: :popcorn: :popcorn:
Willy

Offline propforward

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Re: Coles C-611
« Reply #82 on: May 13, 2021, 03:59:45 AM »
Some good set up tips here that I am looking forward to trying.
Stuart

Forging ahead regardless.

Offline gunna

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Re: Coles C-611
« Reply #83 on: May 13, 2021, 09:41:42 AM »
Thank you Jo for the great explanations and reasons of/for what you are doing. Love it!
Ian.

Offline Jo

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Re: Coles C-611
« Reply #84 on: May 14, 2021, 03:09:12 PM »
Thanks for following along  :)

I spotted that Coles claimed in their original advert that they provide CR Steel for the crankshaft - the one that came with this was a casting  :noidea:

A few odds and ends:

Steam chest cover: This is over sized and not square so what we are going to do is find the centre of the cover with a wobbler:



And then drill the four mounting holes 5BA clearance (3.2mm)



Repeat with the steam chest:



this time we have a long way to go through the chest so there is a chance that the drill is going to wander so I am using a slightly oversized drill (3.3mm) and one that provides better side clearance for the swarf:



Check it fits:



And move on to something more interesting: the valve. This is made of gunmetal, gunmetal marks easily, very easily and can distort  :toilet_claw: So I am not going to hold it round the valve but square up the top so that I can clamp the vice around that:



You can see I have marked the direction of the valve spindle. This is to make sure I mill the slot the right way round on the valve face.



Next mill the surface flat. This casting is tight so you can see I have skimmed off as little as I can get away with and there is still a drop mark in the centre (that is about to be milled away)



Now for the exciting bit  :paranoia: Milling the pocket. First calculate the distances out from the centre for each of the edges minus half the diameter of the cutter:



With the milling cutter in the centre I am plunging to the depth of cut I want to make. I have chosen 0.3mm for the first cut with 0.4mm for subsequent cuts.



Mill out to the side of the pocket stopping slightly short.



Move the cutter up to the timing edge of the pocket leaving it slightly short



Follow along this important edge to the side of the pocket, down the side, up the other important timing edge and finally return to where we were first milling. And try to take a picture that is in focus  :Doh:



Now for the critical bit: Measure the size of the slot:



What you can see is that the pocket measures 12.4mm and what I want is 12.7mm so I am going to adjust the distance I move out the cutter so that this dimension is correct (it is better that this measurement is undersized than over  ;)



Round and round following the same pattern each time not forgetting to take out the centre while dropping the cutter in the centre of the pocket. Until:



If you look you can see a very small burr, this is easily taken off by rubbing the valve on a piece of fine abrasive paper



And rub the outside with a file to remove any burrs there. Before going any further introduce the valve to the chest:



I need to do a bit more work there... But this post is long enough for today.

Jo
« Last Edit: July 28, 2021, 03:00:58 PM by Jo »
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Offline tvoght

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Re: Coles C-611
« Reply #85 on: May 14, 2021, 04:59:27 PM »
I am watching Jo. A good build and tutorial all in one.  --Tim

Offline Admiral_dk

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Re: Coles C-611
« Reply #86 on: May 14, 2021, 10:26:50 PM »
Still following and enjoying your explanations  :ThumbsUp:

Per

Offline Jo

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Re: Coles C-611
« Reply #87 on: May 23, 2021, 03:52:29 PM »
Thanks Guys  :) I've been a bit side tracked:  the weather has been horrible and I have just started a couple (yes 2 at the same time  ::) ) of rather nice new cross stitch pieces that have been taking my attention. But today....


If you recall the valve would not fit inside the steam chest so it needs opening up. Hand filing is easy and quick and is less likely to break an expensive long reach milling cutter. I chose to use the mill:



The valve rod guide/gland needs to be added to the steam chest. I have turned up a piece of bronze 8mm diameter and cut the thread using a die.



It is easy for a die to start out of line so you can see I am using the drill chuck against the back of the die holder to keep the die square. You can also use a dedicated tailstock mounted die holder to do the same  ;) I have drilled the centre of the guide 3.8mm for a 4mm diameter shaft and used a countersink to form dip around the end of the hole to encourage the steam packing to go towards the shaft rather than just squash under the gland nut.

And also need that gland nut. This is nothing special just a piece of brass hex with a 3.8mm hole through it but we want the internal thread to end nice and square so I am using a home made D-bit to cut the 7mm hole:



The thread is cut with a tap which is supported from the tailstock to make sure it goes in true:

 

With that ready to go I can use a wobbler to find the centre of the steam chest and the lower edge



from which I stepped up 9.5mm and drilled 7.0mm and making sure the tap went in true tapped the hole for the same thread as the spindle guide.

The guide has been loctited into the steam chest, which will require 24 hours to harden. But as on this it has a locknut everything is firm enough for me to put the gland nut in place and ream through the guide and nut together. You can also see that the spindle is along the centre line of the steam chest:



We now know the height of the valve spindle so it is time to centre on the valve:



and drill it 4.1mm for the 4mm diameter spindle:



Notice this is not a tapped hole  :hellno: this is clearance as we want the valve to "float" and for the steam to push the valve against the port face. This is one of those horrible designs that uses two nuts on either side of the valve:



This makes timing the engine a right pain as you cannot just drop off the Eccentric road and give it a twist  :ShakeHead: you have to faff around with little spanners inside the constrained steam chest area. Lets slide the valve on the spindle and check the side clearance:



Missing Photo  :o of it all mounted on the engine  :slap:


The next bit I am going to think about is getting the crankshaft in place. The reason for this is because it allows us to line things up. This engine came with two cross head castings and one main bearing casting  :headscratch: this means I need to make two replacement main bearings. Yes two not one. Why? Because both bearing need to be made of the same material so that they wear evenly.  As I am a skin flint I have knocked up three pieces for each bearing:



The hole through each is on the centre of the crankshaft and I am using it to align the three pieces for the purpose of silver soldering them together. Before threading them onto a piece of dowel I am applying silver soldering flux to one of the faces:



I did this by dampening the surface and dabbing the damp face into my pot of flux. I should mention at this point Silver Solder flux is Poisonous so no finger licking until after you have washed your hands.

Over to my heating hearth. These are large pieces so I will be using a large nozzle on my propane torch and I have put those two large lumps of metal behind the two bearings to reflect the heat back on the pieces. The first requirement is to heat the pieces so that the flux does its job i.e. it cleans the surfaces - it normally bubbles a bit. I then will waft  ::) the silver solder in the flame to warm it slightly and dip that in yet more flux. The idea is to heat the work such that the silver solder will almost run round the piece without the gas flame, rather than using the gas flame to melt the solder. If you get the temperature right the solder will whizz all the way round the joint:



Once cool they can be removed from the hearth using a pair of pliers:



Never assume they are cool enough to handle with your fingers  :hellno: These can then be cleaned up. I normally leave them in a pickle tank for the time it takes to have a cuppa before washing them off with cold water and giving them a light wire brushing:



We are ready to go. But that will be another day as it is time for some more cross stitch  :embarassed:

Jo

« Last Edit: July 28, 2021, 03:01:56 PM by Jo »
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Offline Bluechip

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Re: Coles C-611
« Reply #88 on: May 24, 2021, 03:28:52 PM »
Hi Jo

Would it not be possible to get the valve correctly set then cross-drill and pin one nut instead of using a lock-nut ??

Or is that just the sort of crackpot idea I would come up with  .....   ::)

Dave

Offline Jo

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Re: Coles C-611
« Reply #89 on: May 25, 2021, 06:56:42 AM »
Would it not be possible to get the valve correctly set then cross-drill and pin one nut instead of using a lock-nut ??

It would be but a lot of work rather than just leaving it with the fourth nut in place.

Jo

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