Nemetts 15cc engine

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Nemetts 15cc engine

This topic has 77 replies, 15 voices, and was last updated 7 January 2017 at 23:33 by Emgee.

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22 August 2011 at 19:03 #2308
wheeltapper
Participant
@wheeltapper
attenpting to build this.
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22 August 2011 at 19:03 #73723
wheeltapper
Participant
@wheeltapper
HI

I decided a while ago to try and build this engine.

heres a few pics of where I’m up to so far.

crankcase nose

cylinder jacket

a start on the head

liner

crankshaft

crankcase

part assembled

thats made a start with most of the big plain machining bits, now for the small fiddley bits.

thanks for looking.

Roy
22 August 2011 at 21:17 #73730
Jeff Dayman
Participant
@jeffdayman43397
Looking great so far Roy, nice job!

JD
22 August 2011 at 21:49 #73733
Steve Withnell
Participant
@stevewithnell34426
Very nice Roy – are you “going for glo or all the way to electronic ignition?
23 August 2011 at 10:13 #73742
wheeltapper
Participant
@wheeltapper
It’s going to be glowplug, I cant be having with all these electronical thingies.

Lets face it, It’ll only run the once ( if it runs at all that is ) then it’ll go on a nice stand .

I’m only making it to see if I can.

Roy
23 August 2011 at 11:31 #73749
jomac
Participant
@jomac
Hi. nice work, Is the crank shaft one piece, or fabricated in sections. Show us a photo when its running. Im’e making a DA 1cc engine, only have to make the carby, also just have to finish making the furnace to cast the crankcases, then its finished.

John Holloway
23 August 2011 at 15:00 #73767
Clive Hartland
Participant
@clivehartland94829
I wonder if there would be interest in the model engineer fraternity for a project to make an engine from stock bar and square ally?

Something easily machined and minimum set ups, fabricated crankshaft etc.

Some of the designs I have seen are out dated and look old fashioned.

Has anyone any good designs to offer?

Clive
23 August 2011 at 17:22 #73783
wheeltapper
Participant
@wheeltapper
Hi Jobac, just saw your question.

the crankshaft is three parts, the web is pressed onto the shaft with the help of some shaftlock and 3 screws tapped into the end on the join line.

then the pin is pressed in, also with shaftlock, although the amount of force it needed to get it in I doubt it’ll ever move.

Roy
23 August 2011 at 18:35 #73787
JasonB
Moderator
@jasonb
Posted by Clive Hartland on 23/08/2011 15:00:30:

I wonder if there would be interest in the model engineer fraternity for a project to make an engine from stock bar and square ally?

Something easily machined and minimum set ups, fabricated crankshaft etc.

Some of the designs I have seen are out dated and look old fashioned.

Has anyone any good designs to offer?

Clive

Have you looked at the latest ME (4411) ? Our own Ramon Wilson is writing up his ED racers, made from a bit of square ally

Dave Parkes also did one a couple of months ago and there have been a few others

MEB are running the Humbug design at the moment, very simple and fits the criteria you suggest. They have a lot of other desin=gns in their back issues as well.

J

Edited By JasonB on 23/08/2011 18:44:32
23 August 2011 at 19:02 #73788
Roderick Jenkins
Participant
@roderickjenkins93242
How’s this? A 10cc four stroke side valve which I designed and made some years ago. The drawings and words are mostly done but I want to make sure that the drawings are right, which really means making it again and taking pictures.

Rod
24 August 2011 at 08:32 #73810
David Clark 13
Participant
@davidclark13
Hi Rod

I would be interested in an article for Model Engineer.

regards David
24 August 2011 at 09:55 #73811
ady
Participant
@ady
I wonder if there would be interest in the model engineer fraternity for a project to make an engine from stock bar and square ally?

The model aeroplane engine fraternity have quite a few models which can be built directly from barstock.

The EZE engine series for example.

Edited By ady on 24/08/2011 09:57:33
25 August 2011 at 14:02 #73911
Johan van Zanten
Participant
@johanvanzanten
Hi all,

I would be very interested in such a side valve engine project.
It ‘s something new under the sun.

Regards, Johan van Zanten.
25 August 2011 at 14:09 #73912
wheeltapper
Participant
@wheeltapper
HI

If I could have my post back for a moment

I’ve finished the piston.

piston rings next, cast iron, yucky job .

Roy
25 August 2011 at 15:28 #73921
Ramon Wilson
Participant
@ramonwilson3
Posted by wheeltapper on 22/08/2011 19:03:15:

HI

I decided a while ago to ‘try’ and build this engine.

(My accentuation)

Roy, from what I see you are doing an excellent job so far. Keep up the good work both in the workshop and on here.

You haven’t said whether this is your own design or not nor what it’s capacity is. Can you enlighten us.

Regards – Ramon
25 August 2011 at 16:44 #73933
JasonB
Moderator
@jasonb
“You haven’t said whether this is your own design or not nor what it’s capacity is. Can you enlighten us.”

There is a clue in the title of the thread as to the capacity

One of the late Malcom Stride’s (AKA Nemett) designs who wrote IC Topics in ME for several years.

J
25 August 2011 at 17:54 #73937
wheeltapper
Participant
@wheeltapper
Thanks Jason

Roy
25 August 2011 at 19:48 #73947
Ramon Wilson
Participant
@ramonwilson3
Oh Dear, yes, thanks Jason

Red face all round – ear to ruddy ear I guess I was too focussed on the pics and text Is that a reasonable excuse?

Still think you’re doing a fine job though Roy

Regards – Ramon
30 August 2011 at 13:09 #74210
wheeltapper
Participant
@wheeltapper
HI

more progress.

from these,

to this,

the cell is AA for comparison.

cheers

Roy
30 August 2011 at 14:47 #74214
jomac
Participant
@jomac
Clive Hi. If you go to the model engine news site, and others, there are quite a few engines that are made from bar stock, (when I learn how to put photos on the site), you will see the Bolearo 18 that I made, from bar stock. You can see other engines from around the world of the same type on this site. Because Im’e a member I have access to a lot of other engines plans, that are well drawn and very detailed, in this site you can also see detailed instructions and machining. Yes, I know that some are old design, and some newer, but as Ramon will testify ??? it a good site, Anyway even if some are older, they are joy and some times tedious to build and run.

John Holloway.
30 August 2011 at 16:17 #74218
Ramon Wilson
Participant
@ramonwilson3
Hi John (H) and Clive – yep 100% testify to that.

Only has one fault and it’s a big one as far as I’m concerned – it’s so informative and vast you can spend hours nay days enjoying oneself to the total detriment of getting anything done in the workshop .

Have you run the Bolaero yet John? Took the Eta’s to our Nats this weekend – pleased to say they were well received. They are running well now just over 8000 on a 12 x 5. Smaller props next time

Apologies to Roy for encroaching his thread

Regards – Ramon
30 August 2011 at 18:40 #74232
Steve Withnell
Participant
@stevewithnell34426
I’m impressed at the rate you are getting on with the build! Took me about 18 months to build the Nemett!

You’ve also got a nice smooth taper on the front crankcase half – mine has a sartorial corduroy finish, as I didn’t have the gibs adjusted quite right! It’s very uniform, so I could claim it was deliberate!

Do post the video of it running, it’s a great noise –

Steve
30 August 2011 at 19:25 #74237
wheeltapper
Participant
@wheeltapper
Hi

You may have a long wait, I hope you’re patient.

the job that worries me is the head, so many things to go wrong. and the cams, and the………………well you get the picture.

I had trouble turning tapers on my lathe because no matter what I did as I turned the topslide handwheel (only one handle) the top wobbled as the handle went round and the cutter went in, out, in, out and I got a scalloped effect.

now what I do is turn the handwheel by the centre nut with a box spanner,no more wobble.

Roy

BTW I dont have a video camera but if its as noisy as you say you’ll probably hear it anyway.

Edited By wheeltapper on 30/08/2011 19:27:27
30 August 2011 at 19:32 #74239
JasonB
Moderator
@jasonb
I was alway tought that you shoul use both hands on the wheel and not the handle, this allows a constant feed and stops that tendancy to lift the slide as the handle comes up.

If its a long taper one of the electric screwdrivers works well on the nut, not a cordless, they are too fast.

J

Edited By JasonB on 30/08/2011 19:33:01
30 August 2011 at 21:06 #74243
Steve Withnell
Participant
@stevewithnell34426
I must admit the head was the one component that had me worried. In the end the only thing I screwed up was milling the locating square on the top, everything else was just a load of patience and keep re-reading Nemett’s article on the build. One thing to watch is avoiding clamping marks on the head, I’m a bugger for not taking care in that department!

The Cams didn’t turn out too difficult, but I did have a DRO on the mill Z-feed by then, it would have been impossible on my Warco mill as the mechanical readout is hopeless for close tolerance stuff. In the article Nemett uses loctite to fix the cams, I was a bit doubtful but they have held tight no problem.

The scalloped effect you described sounds just like the issue I had, but adjusting the top slide gibs fixed it for me.
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