My First Stationary Engine

[JasonBModerator @jasonb]

Ron, if you wanted to try the alternative valve ports then give this a go. 4.0mm holes instead of 3.5mm and I have shown the X & Y positions which should make it easier setting them out rather than using the angled line and PCD that Julius has on his drawing.

Having repaired a Mamod traction engine for someone over the weekend I'm tempted to build one of these to the Original Muncaster sizes and see if I can add a reverse function along the lines of what the Mamod uses.

[Ron LadenParticipant @ronladen17547]

Thanks Jason for doing this its appreciated I think I will go with it on the engine.

I never had a Mamod traction engine but did have the basic Mamod donkey boiler when I was about 10 years old, had hours of fun with that I remember it having one or two tools which you could connect to it.

It will be interesting to see If you do decide to build the engine with the Mamod reverse.

Thanks again

Ron

[JasonBModerator @jasonb]

Posted by Ron Laden on 26/01/2020 19:15:21:

…… did have the basic Mamod donkey boiler when I was about 10 years old, had hours of fun with that

The RSPCA have put a stop to that now

[geoff walker 1Participant @geoffwalker1]

HI Ron,

Yes it is an airbrush compressor, got it from RDG, very pleased with it.

Only used it for running engines and it's fine for smaller models but the tank lacks the air capacity to run larger engines at high speed for an extended period.

Geoff

[Ron LadenParticipant @ronladen17547]

Made a start this morning with the cylinder, its one piece having the valve block and top flange but the cylinder is open ended which I went for in ease of boring so needs an end cap which I will Loctite in.

Quite pleased with it and certainly enjoyed making it.

[geoff walker 1Participant @geoffwalker1]

Looks good in brass Ron.

I enjoyed making the cylinder as well and like you I left it open and turned a cap to fit

You'll have fun making the standard as well.

Geoff

[Ron LadenParticipant @ronladen17547]

I have no experience of lapping in, would appreciate some advice on how to lap in the aluminium piston to the brass cylinder also the abrasive paste I will need.

Thanks

Ron

[Ron LadenParticipant @ronladen17547]

I got some more done today, the cylinder is not far from completion. I have the piston to lap in and an end cap to make and fit to the bottom of the cylinder, I also want to change the screws for a smaller head they are some standard M3 hex at the moment which I had on the shelf.

[JasonBModerator @jasonb]

I use silicon carbide powers in various grits down to 1000g mixed with a little oil. For something a basic as this engine you could just turn a piece of hardwood to a good git in the bore and use that as the lap working down through the grits.

Then the piston can be lapped until it just starts to enter the bore with some wet and dry supported by something flat like a steel rule of piece of MDF. once it starts to enter use plenty of oil and a little of the finest abrasive and lap the piston into the cylinder if using no rings.

If using rings then take it down until it enters the cylinder by using the wet & dry.

For more critical jobs then an expandable metal lap can be made to lap the cylinder together with an external one to do the piston.

Ramon's thread on MEM is worth reading for a more in depth description.

Progress is looking good so far.

[Ron LadenParticipant @ronladen17547]

Thanks Jason, thats helpful I will search out some silicone carbide powders, would you happen to know if you can get sets i.e a selection of various grits.

Ron

[JasonBModerator @jasonb]

Something like this will last a lifetime though the 80g is too coarse to be useful

[Ron LadenParticipant @ronladen17547]

Thanks Jason, got it on order should see it tomorrow/Monday.

Ron

[Ron LadenParticipant @ronladen17547]

I need to buy/make some parts for when I connect the engine to the compressor. The drawing shows the in/outlet nipples as having a central hex for fitting with M6 either side and a 3.5mm through hole. I am thinking the M6 for the tube connection is there to provide some grip for a push on fit, is that the norm for the tube connection..?

Thanks Ron

[JasonBModerator @jasonb]

Bearing in mind that they are metric fine I would say he intends the adaptor to take a female threaded hose.

However you have a few options

1. Tap M6 x 1 or M6 x 0.75 and make a barbed connector to have a bit of hose pushed onto it.

2. Tap as above and make an adaptor with the other end threaded to suit the airbrush hose fitting

3. Tap M6 x 1 and then buy a push fit connector for say 6mm OD PVC tube and get a similar connector to fit the 1/8" or 1/4" BSP outlet of your compressor to go on the other end. If you do this I would suggest you use a screw down regulator at the compressor end as they are simple, cheap and easy to control speed with. You can see I have several on my manifold.

4. None of the above and bodge something with a heated tube and gaffer tape

[Ron LadenParticipant @ronladen17547]

Jason, I know I am a pain but having no experience of these engines can I trouble you to double check something for me.

If my calculations are correct and working from the drawing dimensions I make it that the piston at BDC covers the inlet/outlet valve, would that be correct..? I imagined that at BDC it would be just shy (above) the valves but maybe not.

Thanks

Ron

Edited By Ron Laden on 31/01/2020 07:43:04

[Ron LadenParticipant @ronladen17547]

Thanks for the hose options Jason.

Ron

[JasonBModerator @jasonb]

Will have a look later for you

[geoff walker 1Participant @geoffwalker1]

If my calculations are correct and working from the drawing dimensions I make it that the piston at BDC covers the inlet/outlet valve, would that be correct..? I imagined that at BDC it would be just shy (above) the valves but maybe not.

Hi Ron,

On the original muncaster engine the top of the piston is half way across the port at BDC, which is how I set mine.

Not sure it would be a good idea to cover the port completely, but I'll be interested to see what Jason thinks.

Geoff

[JasonBModerator @jasonb]

As far as I can make out Julius has it so that there is some of the hole exposed at BDC

Crankshaft ctr line to cylinder pivot = 78mm add to that the distance from pivot to ctr of hole in cylinder = 15mm Plus half hole diameter (3.5 / 2) = 1.75 giving a total length of 94.75mm.

Big end 13mm less hole set down 5mm = 8mm plus spigot = 6mm plus unthreaded length of piston rod ( 59-7) = 52 Plus piston thickness = 8mm Total length 74mm

94.75 – 94 = 0.75mm of hole exposed

This is fine as the area will still be larger than the anount of port open will be less than that until the piston is 5mm or so on it's way back up by which time all the 3.5mm hole will be exposed. I would not want to see it totally covered as you may get a bit of bounce if any trapped air is being compressed by the piston if there is no way out for it.

[Ron LadenParticipant @ronladen17547]

Thanks Jason, thats good news I will carry on as per the drawn dimensions, also pleased with the 0.75mm of the hole exposed thats what my reckoning came out at.

One other thing that I have considered, unless I am missing something is there any reason why the inlet/exhaust holes cant be run straight through to the back of the column instead of through 90 degrees and out of the sides. I was thinking it would be a tidier option for the airline connector than out of the sides…just a thought.

Thanks

Ron

[JasonBModerator @jasonb]

You could take them through to the opposite side but if using M6 threaded unions they would be too close unless you offset the threaded holes so they were further apart.

Alternative would be to drill right through 3mm then open the ports to 3.5mm for half depth. You could then simply Loctite in a couple of bits of 3mm tube and just push a hose onto whichever one you wanted.

J

PS I think I have sorted out the geometry for a reversing version at almost original Muncaster size

[Ron LadenParticipant @ronladen17547]

Thanks Jason, I was thinking of just one M6 push in type connector and leaving the exhaust hole with no fitting..?

The reversing version will be interesting to see.

Ron

[Ron LadenParticipant @ronladen17547]

Morning Jason,

I am in the process of turning the piston in some 6082, I am going to give a pair of oil V grooves a try which you mentioned, I was thinking 2mm in from each end..? also how deep do the grooves need to be, I,m guessing not too deep..?

Thanks

Ron

[JasonBModerator @jasonb]

0.5mm deep would do and your 2mm in will be fine

[Ron LadenParticipant @ronladen17547]

Posted by JasonB on 01/02/2020 10:06:33:

0.5mm deep would do and your 2mm in will be fine

Thanks Jason.

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