Jowitt MkII Popett Valve Engine Build

[JasonBModerator @jasonb]

I like to test run my engines before painting as it saves risking any damage to the paintwork if you have to strip things down to do any alterations. If your fits are OK you should be able to test without any gaskets and just one O ring. As you assemble the engine check that it turns over smoothly after each bit is added as this makes it easier to see where things may be binding.

The inlet eccentric should be set so that the inlet is open from TDC until about 5degrees before BDC. The Exhaust should open at BDC and close 5deg Before TDC.

Add a drop of oil to the moving parts and connect up some air and see how it goes.

If all goes well then the engine can be stripped for painting. Give the parts a wipe over with thinners, prime and then top coat, I used spray cans on this one and settled on Ford "Moss Green" For the base I went with a simple piece of Yew that I had been seasoning for a few years.

As you build the engine back up check for smooth running as a bit of stray paint can throw things out. If all is well you should be able to flick the flywheels over like this before the conrod is fitted, the valve springs do slow things down but you should get quite a few turns and a nice gentle stop.

The finished engine, not bad for 29day from start to finish working a couple of evenings a week and part of the weekends.

And finally The complete engien running on a couple of psi of air

I hope this has been of interest to someone, there is very little feedback on this forum so its hard to know if I'm just posting for the sake of it or if anyone is finding it useful. I would like to thank the couple of members who have PM'd me with a few comments on the drawings which has allowed me to make the odd alteration so they should be Ok if anyone wants to have a go at making one of these engines.

The End, Jason

[Chris GunnParticipant @chrisgunn36534]

Jason, thanks for the series, I have downloaded the drawings and intend to make one when I have finished my Stuart Turner Undertype.

Chris Gunn

[Roderick JenkinsParticipant @roderickjenkins93242]

Jason,

That's very public spirited of you. Another model to add to the to do list.

Many thanks,

Rod

[fishy-steveParticipant @fishy-steve]

Just read the thread from start to finish. Really enjoyed it. Thanks Jason!

Steve.

[Roger Provins 2Participant @rogerprovins2]

Thanks very much Jason, excellent!

I've downloaded all the drawings and will attempt a build when I cleared my current projects.

Roger

[ianjParticipant @ians]

"so its hard to know if I'm just posting for the sake of it or if anyone is finding it useful"

Jason.

You are certainly not wasting your time. I've followed this thread from the start & have been down loading the plans. I intend to build this engine in the near future. I always find your post's interesting and informative..

Ian

[Martin King 2Participant @martinking2]

Hi Jason,

I totally second the above remarks and thank you very much indeed for this interesting and very informative thread. I am coming along nicely with my attempt at modelling this in 3D using Fusion 360 which is proving to be both challenging and great fun!

The step by step format of your thread really makes one want to have a go at this attractive yet not too complicated (I may have to remember I said that latert! ) and I look forward to trying it when I can.

Thanks again and best regards,

Martin

[Martin King 2Participant @martinking2]

Out of interest, is there any way to download this entire thread complete with pictures and links into a format like pdf or similar? If so are there any copyright implications. Obviously for private use only.

Martin

[MuzzerParticipant @muzzer]

Beautiful work, amazing craftsmanship and attention to detail – and interesting machine. Thanks for posting – I love build threads!

Murray

[JasonBModerator @jasonb]

Thanks for all the kind comments and good to know I may have tempted a few of you to have a go.

Chris, It would be nice to see what you are upto with your undertype as its not a model that ios often seen. Unless you are keeping that for another article after the Garrett.

Martin, again it would be nice to see how your 3D drawings are progressing and also hoe Fusion can render the image. Also thanks for your PM's. I will see what can be done about making a single article.

For anyone who has been downloading as the parts have been described I would suggest checking you have the most upto date drawing as there have been some revisions, mostly to make things clearer but there were a couple of small errors on the oiler bosses. The full list of drawings is here on dropbox.

Now hurry up and get your versions complete as I have almost finished the drawings for the next engine. This will share the same 24mm bore and will be an Entablature engine as I have some O rings and green paint left over

J

[Chris GunnParticipant @chrisgunn36534]

Jason, I will take a few pictures of the Undertype in due course, as I am still working on it. I was lucky enough to win an auction for the drawings and castings on a well known auction site.

The cylinders and crankshaft were already machined to a very high standard indeed, so as I have not made it all maybe it is not suitable for publication. It is a nice model I always wanted to make back when I was a lot younger but could not afford the castings. Then it was discontinued so I thought I had missed the boat. The engine goes back to a design by Henry Greenly, and was revisited by H A Taylor who did a series in the Model Engineer starting in March 1971. The design was then taken up by Stuart Turner who produced the castings, but I am not sure when the engine was dropped from the range. It is a change from the 4CD for sure, while I decide whether to make another traction engine.

Chris Gunn

[MuzzerParticipant @muzzer]

What CAD did you use? 3D PDF looks good.

Murray

[JasonBModerator @jasonb]

Alibre PE which is now sold as Cubify Design.

[MuzzerParticipant @muzzer]

Aha. I used to have Alibre Free, then trialed Geomagic when I lost it – similar difference. Nice app.

[Martin King 2Participant @martinking2]

Hi Jason,

Been a bit busy but still trying with Fusion 360.

Here is a pic of the base assembly and my first ever play with a render, excuse the bright colours, got carried away with the materials list!

Still finding areas of this program exasperating but fun! Trying to import the cap screws from Mcmaster Carr and duplicating them is less than intuitive and the hierarchical (?) system for components has to be just right or all sorts of problems arise. However that said I am a total novice at this and the power of this program leaves me amazed constantly.

Wjhen I get my new bandsaw i have the ally billet standing by to make a start on this from yours (& mine??) drawings

Regards,

Martin

[Chris GunnParticipant @chrisgunn36534]

Jason, as said earlier I was inspired to make a start and had a rummage around and found 2 round cast test pieces about 5" diameter I scrounged from a foundry years ago, and parted off a slice and then thought I would do 1 for each of my grandkids, 4 in all, so parted off 3 more slices. I have made everything except the con rod and piston and the flywheels since the beginning of May for 4 engines all from the come in handy box. I have just bought the Perseus flywheels from Reeves, I had to get 10 to get a discount, so I have 2 spare Perseus flywheels. If anyone wants these PM me, first come first served. I will take some pics at a later date.

Chris Gunn

[JasonBModerator @jasonb]

Look forward to seeing the pics

[Ron LadenParticipant @ronladen17547]

Morning Jason,

I am thinking of having a progress thread when I start the Jowitt and there probably will be some questions, are you happy for me to post the questions on here or keep them to my thread.

Ron

[Howard LewisParticipant @howardlewis46836]

An excellent record of the production of this engine.

As a non engine builder, I stand in awe of the skill and patience of Jason and hid followers.

Some of you may already know, but Stan Bray is still with us, and active. He exhibited and helped me Steward on the Peterborough Society of Model Engineers stand at the festival of Model railways, last December.

Every January, he comes a gives a talk to us, with plenty of humour as well as information!

Fingers in the wrong places again

Howard

Edited By Howard Lewis on 13/02/2020 12:53:42

[JasonBModerator @jasonb]

Ron, if you do your own thread I can put a link here for anyone wanting to see what you are upto.

 

Thank's Howard, though recent posts suggest I'm doing it all wrong

Edited By JasonB on 13/02/2020 13:08:14

[Ron LadenParticipant @ronladen17547]

Thanks Jason,

What are you supposed to be doing wrong..?

[JasonBModerator @jasonb]

Apparently I should just have used the biggest drill see this thread

[JasonBModerator @jasonb]

Ron has spotted an error on the drawing for the exhaust valve rod which was shown too short. Revised drawing now available here

[Author]

Posts