Author Topic: An English Classic ? A 5cc version of the ‘ED Mk IV 3.46 Hunter’  (Read 4831 times)

Offline Ramon

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Re: An English Classic ? A 5cc version of the ‘ED Mk IV 3.46 Hunter’
« Reply #15 on: February 24, 2018, 08:21:41 AM »
Dang Whiskey ya plumb twig'd ma ploy - I'll het thinka summat else noww  ;D

At one time here paraffin was used as a home heating fuel - I guess many will remember that characteristic but not unpleasant smell when you visited a home that did so. It was cheap as chips then and available everywhere - now it's as dear if not dearer than petrol and only obtainable it seems in garden centres. Reminds me - I need to get some for this year.

Near finished the ali bits for this yesterday and was out last night so will pop some pics later today

Tug

"I ain't here for the long time but I am here for a good time"
(a very apt phrase - thanks to a well meaning MEM friend)

Offline Craig DeShong

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Re: An English Classic ? A 5cc version of the ‘ED Mk IV 3.46 Hunter’
« Reply #16 on: February 25, 2018, 02:31:58 AM »
Watched the video, YOW! that thing drinks fuel like crazy! You're bringing back memories.

I remember control line flying in my teen years (this would have been the early 1960's).  Here in the USA it was glow engines, and the 35 (I assume .35 Cubic inch?) was a standard.  My buddy had a FOX 35 stunt that ran like a dream.  I had a FOX 35 rocket that was a "combat" engine and it just ran flat out.

I don't remember any diesels, but there must have been some.  I'm going to have to follow this build, looks VERY interesting. :whoohoo:
Craig

Offline Ramon

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Re: An English Classic ? A 5cc version of the ‘ED Mk IV 3.46 Hunter’
« Reply #17 on: February 25, 2018, 12:37:19 PM »
Hi Craig - nice to see a 'new face' thanks for looking in and glad it's provided a tang of nostalgia for you. I flew control line throughout my life from the age of thirteen. Though I have not flown since 2006 I still have two stunters hanging in the garage - a Nobler and a T'Bird.

Had a couple of Fox35's which were great motors for stunt - I think it has the reputation of being the longest model engine in production. It was a light and easy to run motor if a bit noisy. My preference however was for the OS Max 35 S which like the Fox 35 would run 4 stroke/two stroke if set right, right out of the box. I still have three from around twelve I was using at one time. Had a Fox 36 which was totally different kettle of fish - dreadful motor which I struggled with for some time before switching to the OS's.

Re the fuel guzzling - that was just it's second run from being built so was set very rich. None of the engines built so far have had much running - usually just once a year at a model event. Hope you enjoy the rest of the thread.



I now have all the ali parts save the con-rods done and have surprised myself how quickly the parts have been made. This is the work done so far so as you can see there is not much left to do


The crank shafts were done in my usual way of using a combination of EN24t and high tensile cap head material. This saves on En24t and has proved to more than stand up to the forces involved. The fixture is for turning the crank pins.....


.... using the faceplate.


Finished except for the taper for the prop driver. Had to get one of those small revolving centres from Arc Euro to do that. Brilliant - should have bought one years ago  ::)


The cylinders do not have a liner and as such are turned from leaded EN1a. The machining was relatively straightforward but the two bulges that are over the transfer passages required a different approach which you may find of interest .......

First up was to finish turn the bore and rough turn the basic ODs


Make a new expanding mandrel to suit the bore and machine the fins and lower flange dimensions


Then modify an old one to hold it on the mill .....




The teeth of an end mill cutter were modified on the offhand grinder.....


...... to plunge mill the transfer passages in to an exact depth


Set back on the longer mandrel the exhaust side of the case had the relief milled in


Finished example and the transfer side to do - the bulges required can be seen in the drawing. I would assume the original was machined on a copy lathe but with no access to such another means was sought.


A fixture was made to hold the cylinder via the hold down bolt holes. The two larger holes sit on the centres of the transfer bulge radii


A block was set square to the mill table with a pin set in for the fixture to rotate about


then by rotating small movements and clamping the radius was slowly formed. Once done the cylinder was moved to the second hole and the machining repeated


Back on the small mandrel to cut the scallops out - the bulges can be clearly seen here


And finally - finished ready to lap



That's it - have to go - Sues chomping at the bit - lunch with the in laws - you know the score

Hope that's of interest - I was well pleased with the way those transfer passages turned out - hope that's of use to some one

Regards - Tug

No time to preview this so any mistakes will be rectified later  ;)
"I ain't here for the long time but I am here for a good time"
(a very apt phrase - thanks to a well meaning MEM friend)

Online sco

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Re: An English Classic ? A 5cc version of the ‘ED Mk IV 3.46 Hunter’
« Reply #18 on: February 25, 2018, 02:18:01 PM »
Slick work as usual Tug!  Can you explain why you ground the end mill in order to cut the transfer ports (~10 pictures from the begining of the post)?

Simon.
Ars longa, vita brevis.

Offline Ramon

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Re: An English Classic ? A 5cc version of the ‘ED Mk IV 3.46 Hunter’
« Reply #19 on: February 25, 2018, 10:35:42 PM »
Hi Simon - just got back home, well fed and well over watered  ;)

If you look at the drawing on the same image you can see I have tapered the transfer passage into the cylinder to assist the flow. Modifying the cutter was how I achieved a reasonable transition. As long as the actual edge does not stray far from it's designed position then the timing remains fairly close to the designed amount. The actual shape is not that important hence the freehand grinding. Usually the passages are cut into the crankcase with the porting cut into the liner to define the timing giving much larger passages but this is how the original was made. 

Bear in mind this is predominantly a model engineering exercise and not an attempt to make anything with exceptional performance - as long as it runs reasonably well I'll be more than happy - hopefully you'll 'hear' the result at Forncett ;)

Regards - Tug
"I ain't here for the long time but I am here for a good time"
(a very apt phrase - thanks to a well meaning MEM friend)

Offline Ramon

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Re: An English Classic ? A 5cc version of the ‘ED Mk IV 3.46 Hunter’
« Reply #20 on: March 02, 2018, 09:07:00 AM »
Just a small update guys,

All parts save the piston, contra piston and rotors are finished. I'll do the cast bits later with other cast bits for the Corliss.

The con-rods were made from 'Alumec 89' a very tough grade of ali.


The spinners were done in the usual fashion of a series of flats then flared using a scraper made from an old file.


The cylinder head fins were done using a home made cutter - usual silver steel, heat treated, quenched in oil - no tempering for max hardness, teeth sharpened using a worn diamond file.


A shot of the intake parts


The needles were made from mild steel rod run down to 7BA diameter. The thread was put on by die and the tail end supported in a brass centre. The taper was then put on just by filing until the end parted.


...then finished off by the usual method of supporting it on a wood support/guide to finish file and smooth - works very well


It'll be a while before the final parts are done and assembly can take place so until then I hope you've enjoyed this little diversion from the Corliss build

Regards for now - Tug
"I ain't here for the long time but I am here for a good time"
(a very apt phrase - thanks to a well meaning MEM friend)

Offline Roger B

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Re: An English Classic ? A 5cc version of the ‘ED Mk IV 3.46 Hunter’
« Reply #21 on: March 02, 2018, 09:22:11 AM »
Very nice  :praise2: I like the setups to deal with the passages/ports  :)
Best regards

Roger

Offline Vixen

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Re: An English Classic ? A 5cc version of the ‘ED Mk IV 3.46 Hunter’
« Reply #22 on: March 02, 2018, 11:03:41 AM »
Nice clean work Tug  :ThumbsUp: :ThumbsUp:

Mike
It is the journey that matters, not the destination

Offline Admiral_dk

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Re: An English Classic ? A 5cc version of the ‘ED Mk IV 3.46 Hunter’
« Reply #23 on: March 02, 2018, 11:45:59 AM »
Some very nice parts to your usual very high standard.

Thank you for showing the details about supporting the needle with a piece of wood - I would not have though of that, but obvious when you see it  :ThumbsUp:

It looks like you did the conrod on the lathe except for the holes.

Offline Dave Otto

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Re: An English Classic ? A 5cc version of the ‘ED Mk IV 3.46 Hunter’
« Reply #24 on: March 03, 2018, 01:12:50 AM »
Beautiful work and great photos!
Thanks for the update Tug.

Dave

Offline Ramon

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Re: An English Classic ? A 5cc version of the ‘ED Mk IV 3.46 Hunter’
« Reply #25 on: March 03, 2018, 10:43:48 AM »
Hi Guys - thanks for looking in and your kind comments  :ThumbsUp:

Roger - I was very pleased the way those 'bulges' machined up using that method. I had tried a similar set up on the bosses on the crankcase and found it worked well if a bit time consuming.

Per - Yes the con-rods were done on the lathe using form tools after drilling and reaming on the mill.  I didn't take any pics but I did describe the making of similar rods on the ETA thread here http://www.modelenginemaker.com/index.php/topic,1334.75.html - you'll need to scroll down to post #87



Regards for now - Tug

"I ain't here for the long time but I am here for a good time"
(a very apt phrase - thanks to a well meaning MEM friend)

Offline Ramon

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Re: An English Classic ? A 5cc version of the ‘ED Mk IV 3.46 Hunter’
« Reply #26 on: July 29, 2018, 11:11:37 PM »
Hi Guys - With the Forncett ME Day looming on the not too distant horizon I thought I'd spend a bit of time to bring this build to an end and hopefully have something new to run this year.

As previously said virtually all parts save the pistons and rotors have been made so lapping the cylinders was the priority in order to tackle the pistons.

A previously made lap for a larger bore was skimmed to suit. Don't pay too much attention to the scratches - they were caused by trying the cylinder on before applying the lapping compound and the camera makes them look far worse that they are.



It didn't take long with the initial 320 grit to make them disappear


The liner was lapped in three stages - cleaning lap and liner between each in a jar of cellulose thinner

After the initial lapping to remove tooling marks - 320 grit carborundum paste


The interim using 600 grit


And finally a 'polish' with 1000 grit.


The pistons were turned from Meehanite the inner profile turned and milled to lighten as much as possible. Held in the usual fixture they were lapped using another 'recycled' brass lap from a previous build using 320 grit until the piston would just enter the cylinder bore at the base. A quick lap with 600 to smooth the finish and the slow process of lapping the piston to the liner by hand could begin.


No pics of that process on this build but these from doing similar on a previous engine will show the process


The piston is mounted on the Tee bar with a brass pin and a minimal amount of 1000 grit paste is applied with plenty of paraffin and oil lube. (95% to 5 %)


The piston is entered into the bore with a slow twisting motion gradually abrading both surfaces to a perfect fit. (It was described in detail on the Lapping and Honing thread)


This is a slow process and one which can't be rushed - patience is key. Despite having done it many times now there are still moments where I think it will never wear in but it always does. Once nearing the top of the stroke it's important to constantly take the piston out and clean it then go back in with just plenty of lube allowing the residue in the liner to take that final few microns off

The gudgeon (wrist) pins were made from steel dowels. Case hardened to provide a good wearing surface they have a soft core which can be drilled to accept the brass wear pads at each end. A fresh dowel requires the end cutting off to get past the hard surface for drilling...


Then the pin can then be cut adding a small amount for trimming back to finished length with a carbide tool


And that's it - with the rotors made from Tufnol it's time for a final clean of parts and assembly.



That's end of play tonight - should be able to test one tomorrow :)

It's been nice to have something to show from tha ol shid - hope that's of interest to some

Regards - Tug
"I ain't here for the long time but I am here for a good time"
(a very apt phrase - thanks to a well meaning MEM friend)

Offline Tennessee Whiskey

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Re: An English Classic ? A 5cc version of the ‘ED Mk IV 3.46 Hunter’
« Reply #27 on: July 29, 2018, 11:37:27 PM »
Well look at you go old boy  :ThumbsUp:. I can’t wait to hear these twins running. I bet I know someone else who’ll enjoy them at Forncett also  :stickpoke: ;)

Cletus

Online b.lindsey

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Re: An English Classic ? A 5cc version of the ‘ED Mk IV 3.46 Hunter’
« Reply #28 on: July 30, 2018, 12:48:44 AM »
Beautiful engines Ramon. Hope they will run as good as they look.

Bill

Offline Ramon

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Re: An English Classic ? A 5cc version of the ‘ED Mk IV 3.46 Hunter’
« Reply #29 on: July 30, 2018, 08:34:41 AM »
Thanks guys - just to say it's been an early start, the first one has been assembled and I've just given it a first and very tentative run (It was before eight in the morning so need to be a bit considerate - I guess my neighbours will be most impressed) Whatever it's a runner but does need a bloody good clout to get it over compression  ::) and yes - no bitten fingers - yet ;D

More later - Tug
"I ain't here for the long time but I am here for a good time"
(a very apt phrase - thanks to a well meaning MEM friend)