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Member postings for John Somers 1

Here is a list of all the postings John Somers 1 has made in our forums. Click on a thread name to jump to the thread.

Thread: Open Source models
13/05/2012 05:57:45

Jason and Geoff

and all others who clicked on Jason's link in the expectation of seeing my build guide on Stan Bray's Opus Proximum vertical mill engine. The link has now been fixed or you could go direct

sorry about that - sometimes making a start in model engineering seems a lot easier than setting up a website !



Edited By John Somers 1 on 13/05/2012 05:59:03

Edited By John Somers 1 on 13/05/2012 06:00:43

Thread: Jan Ridders Pressure-controlled Two-stroke engine
13/11/2011 09:08:42

I don't imagine the fuel in the UK is any better. I had a problem finding Colemans although I finally found some on the internet which worked out around £9.00 per litre including shipping.

Having used up a litre of Coleman fuel during my efforts to get Debbie to run I was googling for a local supplier when I came across Aspen 2T a ready-mixed (2%) alkylate petrol for all 2-stroke small capacity engines with a recommended mix of 2% or 1:50. (There’s also Aspen 4T for four strokes).

5 litres cost me under £16.00 and as Aspen fuel is much more widely available it saved me a package on postage costs. I was surprised to find that compared with Coleman fuel Aspen runs on a much leaner mix. With Colemans I was having to virtually close the vapour carb air valve to get Debbie to run. With Aspen the valve is just about fully open. She ran sweeter and uses far less fuel.

I am also informed that Aspen doesn't deteriorate with age like conventional unleaded.

I understand that Aspen is produced in Sweden and although its widely available in the UK I don't think Jim had any success in finding any in Australia.

If you are interested in my experiences with Debbie you'll find the full story at
Mine doesn't run any smoother than yours and I note Debra also requires a restraining finger just like Debbie.
John S
12/11/2011 22:06:22
Debra sure looks good in her new finery and all 'blinged up' in those original colours. A true lady.
Job done and in great style.
John S
31/03/2011 16:32:08
I can hardly contain my excitement at finally having succeeded in getting my Debbie to perform as Jan intended. The final chapter on this ongoing saga can be found at
As a bonus I also found a cheaper and to my mind a better fuel for our IC engines Aspen 2T and 4T fuel. Anyway much more info on my site at
Thank you to one and all for your interest and support.
John S
Thread: Lathe Thread Stop
16/03/2011 16:53:09
Thanks Terry

Yes I can see that but I don't think there is any reference on my site to a cross slide stop, maybe there should be as I can see it being as useful as a carriage stop for certain machining applications.

So much still to learn !

16/03/2011 16:11:26
Hi Michael
I wonder if you may have been confusing the thread stop with the carriage stop featured on my site (Scroll down to item 7 for more info).
John Somers
Thread: Jan Ridders Pressure-controlled Two-stroke engine
15/03/2011 09:57:17
Arise Sir Jim !

Well deserved congratulations ! Your untiring efforts and tenacity have at last paid off. You must be over the moon (or is it under the moon 'down under' ?

You have given renewed hope to all 'Debbie' builders including myself. I can't wait to get into the workshop to make a Jimbo piston.

Best wishes

John Somers
14/03/2011 15:13:20
Tried the grease test and there was some evidence of grease being sucked into the cylinder though difficult to be sure due to restricted space. Anyway it prompted me to machine up a phosphor bronze bush, very tight fit which eased after a few turns of the electric starter but no improvement with engine fourstroking as before.
Added an inset 'O' ring to the bush which tightened around the piston rod when the seal cover was tightened. Sorry to say still no improvement.
Thanks for your continued interest.
John Somers
14/03/2011 10:19:55
I like that idea Ian. I shall try a temporary seal of grease and see what happens. In fact I will go and do it now !
John Somers
14/03/2011 10:14:56
Hi Jan
This was an area where I also felt an improved seal might be beneficial in minimising the suction of air into the chamber below the piston. As you say this could reduce compression and weaken the mixture.
My solution was to split the Teflon bush and insert a seal of graphite string the compression of which can be controlled by the careful tightening of the seal plate. I felt that this would offer less friction than an 'O' ring.
This modification seemed to provide an improved seal but sadly little improvement in the ability of 'Debbie' to run unaided.
John Somers
03/03/2011 12:28:22
Optimism is high following Jim's eureka moment and fingers are firmly crossed that this at long last may be the answer in overcoming the running problems with both Debra and Debbie.
Whilst Jim explores the benefit of a larger flywheel I am planning to make a modified version of Jan's vacuum carb incorporating a variable throttle.Could the misfiring and four stroking characteristics of all these engines be due to fuel starvation ? In an attempt to find out I am planning to construct a revised version of Jan's vacuum carburetor with a throttle device to adjust the volume of vapour fed into the induction tract. I confess that this is a seat of the pants modification based more on gut feel than any technical knowledge.
As far as adding an additional flywheel or a jacobs chuck, as Ian has suggested, I am advised by Jim that the problem is that the inertia of the flywheel increases rapidly with diameter but only slowly with width. However as I happen to have a suitable cast iron flywheel 'in stock' there would be no harm in adding this to the crankshaft and observing if there is any improvement.
Work continues.

28/02/2011 15:33:44
Hi Jeff
Many thanks for your observations which are much appreciated and very welcome Jeff !
Initially I tried a coil and contact breaker set up which did produce a good healthy spark but for the contact breaker I used a micro switch but this didn't have the stamina for this kind of use. After destroying six of them I replaced the setup with an RCEXL CDI ignition system but became confused between static and dynamic timing. I have now had the difference explained to me by Jim (see his earlier posts on this thread) and am hoping to reset my ignition in the next day or so.
If this doesn't produce the desired result I shall go for plan B which is to try a modified version of Jan Ridder's carburetor which adds throttle control
I have a gut feeling that my engine would pick up and run unaided if I was able to increase the volume of fuel mixture.
I must add that Jim has carried out exhaustive tests to get to the cause of the problem which he, I and others on this forum have encountered - unfortunately with no success.
Jan has been extremely helpful in his efforts to resolve this issue and I am sure he is as frustrated as we all are by our failure to get this engine running.
Like most of us I hate being beat and will persevere a little longer before throwing in the towel.


Thread: MEW for Beginners
24/02/2011 09:45:03
An excellent piece of advice Gordon. If I may I would also add that you should never ever have a cleaning rag anywhere near the lathe - it can wrap round the revolving chuck in a flash and drag your hand in with it.
23/02/2011 14:51:13
I subscribe to the methods put forward by Gordon and Wallace. I was approaching 70 when I purchased my first lathe and had no practical engineering experience. I taught myself by cautious trial and error.

I recall struggling on my first attempt mainly due to the fact I was rotating the chuck in the wrong direction ! I got the hang of things after a few days and have progressed from there. Clearly there is a need for extreme caution guided by large dollops of common sense. I still look in awe at the standard of finish and accuracy achieved by others but at the same time am pleased with the progress made. After a few weeks I was fortunate in finding a mentor who helped me greatly with technique nevertheless my basic machining abilities were largely self taught.

Whilst I certainly do not feel qualified or indeed capable of proving intensive training I am more than happy to show beginners the basics of lathe and mill work, though they enter my workshop completely at their own risk ! Don't come crying to me if you cut your finger.

Should anyone within reasonable distance of the Wetherby area wish to take advantage of my offer then send me a pm thro the site with a bit of info on your interest in model engineering and I will see if I can help.

author of
22/02/2011 09:24:11
Hi Coiln
One resource that is designed to assist beginners can be found at

the site now includes the MIT videos referred to by Alasdair.


Edited By John Somers 1 on 22/02/2011 09:25:10

Thread: Jan Ridders Pressure-controlled Two-stroke engine
19/02/2011 14:05:48
Hello Jan
You have cleared up a small mystery for me. Until the last day or so I wasn't aware that there was an alternative engine to 'Debbie' Simple Two Stroke (which is the engine I think I have built !). My friend Aussie Jim reffered to his 'Pressure Controlled Two-Stroke' that he calls 'Debra' as he felt this made it sound superior. I believe that both Jim's and my engines are both 'Debbie' Simple Two Strokes - am I correct ?
I am currently away on holiday at the moment so am unable to make further progress with my 'Debbie'. My engine spins freely almost to the same standard as yours - 5 revolutions with no compression from plug or chamber, 3 revolutions with just chamber and 1 to 2 revs with chamber and plug in place.
If my engine is not firing consistently on every revolution as Jim has discovered is the case with his, then surely this could be the reason for not running without assistance. Perhaps you may care to look at the short video of me attempting to start my engine. I appreciate that it may be very difficult to advise me from this alone but something may be obvious to you.
With thanks for your continued support on this perplexing issue.

John Somers

Edited By John Somers 1 on 19/02/2011 14:07:11

16/02/2011 13:41:32
It seems that you are homing in on the source of the problem which also confirms Jan's belief that most problems relating to poor running or even non starting can be traced back to the one way valve system. Like you I have spent a considerable amount of time focusing on this valve even trying a square edge seating rather than a taper as suggested by Bogs. I wonder if a very light coil spring to return the ball to its seating might help things though perhaps the resistance may be too high for suction to do its job. At least through your logical approach we have eliminated all other potential problem areas.
Richard raised the possibility that the balls may not be truly round. I have tried balls from different sources with this possibility in mind without any apparent improvement. In using a square edge ball seating I have gently tapped a ball into position to provide a good seal on the seating then replaced that ball with a new one. I really cannot envisage a way of producing a better seal unless a spring assisted arrangement could be made.

13/02/2011 15:31:54
Like Jim I have also recently completed building Jan's Simple Two stroke and like Jim and others on this forum, the engine steafastly refuses to run for longer than a few seconds. It will fire quite happily aided by the 'start' drill and on one occasion ran for something like 30 seconds.
An account of my build is featured on my blog and whilst I am reluctant to abandon this project I am running short on possible solutions to this perplexing problem.
The engine does seem to be very sensitive to the level of fuel in the carb and, more understandably, to fuel mixture. Mine appears to be happiest with a very rich mixture (air valve almost closed). This suggests air is being sucked in further down the induction line but I don't think this the case.
I first tried a coil and micro switch type of contact breaker which produced a healthy fat blue spark but the micro switches didn't appear to have the stamina to be used for this purpose. In the end Ielected to replace with an RCEXL CDI unit in the hope that this may provide a magical cure.
It is curious that a number of people are experiencing the same difficulties and hopefully someone out there might know the answer.
Thread: Opus Proximum
14/09/2010 19:49:27
You are not the first to get your knuckles wrapped upon querying anomalies In Mr Brays drawings. I am curious to know if despite this your endeavours were successful and you finished up with a runner - anyt chance of any pics ?
14/09/2010 16:22:12
It is getting on for ten months (doesn't time fly !) since I started building Stan Brays Opus Proximum and whilst it has been a struggle I am now pleased to report that at last it is up and running. Those interested can see the step by step build log and the final outcome at
John S
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