lil brother air cooled.

[miss_emma_jade]

long time lurker, and i promise to try and search for answers before asking, and im posting this with a disclaimer, ie. im not good at keeing up build logs .

anyway 2019? I think, I bought a partly machined kit from a freind at a swap meet while on holidays in california. it sat in the cupboard for a bit, then last week i did some closer investigation into what was ok and what wasnt.
theres a crank there, the throws are soldered together at the wrong spacings. theres some valves too, theyre tapered and badly finished. no gears. the base has had some machining, mostly close to size, so far usable. the cylinder had neen bored, and sort of faced. its saveable
the flywheels are machined. both roughly the same size etc. usable.
so, I messed around and set the cylinder up on a mandrel nice and accurately, and machined the flats that bolt to the base, id say thats the reference surface , so, that done, ive machined the casting to length and started drilling some holes. at this point the switch on my mill fell apart. ill have it fixed by tuesday hopefully.

tonight I machined the fan shaft. converting to BA as unc bolts are impossibe to get here. tapped the grease cup thread 5/32 x 40 as it seems more workable than 1/8" .

that brings me to my first question? what design has everyone coime up with for tiny grease cups etc? cant remember ever seeing much written about that?

anyway more as I go, I promise.

[Admiral_dk]

First welcome 

There has been a number of Oil- and Grease- Cups over the years - but I will admit that most are the former and the majority are part of a bigger builds .... and sorry but I can't remember where to look ....

Edit : Go to the Frontpage and type "grease cup" in the search vindow => plenty will show up (that should not stop you from posting questions).
The Important part is to search from the Frontpage ...!... if you are in a subforum when performing a Search - you will only get results from that part of MEM (had Me missing quite a few good results before I became aware of this).

Per

[Dave Otto]

Hi Emma, Welcome to MEM!

When I built my Little Brother engines I purchased grease cups from American Model Engineering Supply now Goodshall's https://godshallscustommachining.com/
The cylinder oiler I made from plans obtained from Morrison & Marvin Engine Works.
I made grease cups from scratch for my Pacific engine, there are some photos here; https://www.modelenginemaker.com/index.php/topic,1326.70.html photos starting at post #73.
There are also some photos of the engraving on post 215.

Dave

[Jo]

We have one of these models in our Casting collection 

I'll be following along 

Dave's greasers are very nice 





Jo

[Jasonb]

Dave's photo does not look lihe a greaser more of a drip feed oiler and grease will never come out of those.

On that size engine you will want quite small greasers so maybe a 1/4" x 40 threaded body and the cap no more than 5/16" outside dimention, maybe a bit more for the knurl. In use you fill the cap with grease and screw it onto the body then every so often give he cap a bit of a turn and as it screws down it will push out the grease.



Keep the drip feed oiler for the cylinder, again with teh small scale it's 50/50 if you want to make a proper functioning and adjustable one or a simpleras its more practical

[Dave Otto]

Jason, yup the photo was of a drip olier and there was a link in the text that pointed to the photos of the grease cups, thanks Jo for posting them.
What I do on the small oilers is to just leave the lower glass out and then you can add a few drops there from a oil can.
The drip olier in my photo is this way is this way and the 4 post oilers on the Pacific as well.

[Jasonb]

Ah Jo did not post the photos at the time of my reply, only after.

The use of Greasers seems far more common in the US that it is here where am oil pot would tend to  get used for things like main bearings rather than greasers in the US. Makes sense on little engines that used a two wheel barrow to move them about as the oil would not run out

[miss_emma_jade]

thanks so much for all the replies. a night in the workshop produced four of these. I guess back to cast iron next, or mill work anyway, as soon as I have the switch wired in.. more pics as I go and probably a lot more questions.

[miss_emma_jade]

We have one of these models in our Casting collection 

Jo

Haha.. i guess its not just me that has a casting collection...

[miss_emma_jade]

milling machine working again, so some more progress. I guess I need to get the cranshsft in before i bolt the cylinder to the frame, so as to get it somewhere aligned.

the bore has been machined  6 thou under, what the best way to hone that to size?

order of opperations should be, make crank, fit in block, then line up the cylinder to the centre line, I think.  anyway , a quick update for tonight.

[uuu]

I'm not sure honing is intended to remove as much as 6 thou.  If your bore is parallel and your piston and rings can be made to fit, you might be better using honing, if at all, as a surface finish improver.

I've tried three-legged spring-out honing stones, but have not really got on with them.

I like to make a wooden lap, and have used it with success in getting tapered bores parallel:  A piece of ordinary timber is turned in the lathe until round and will fit in the bore.  Holes are drilled across. so a thin saw can be used to cut down the length, except for the ends.  And a hole drilled from one end toward the middle.  The idea is that a screw can be put in from the end that will belly out the middle of the tool when tightened.   Then I charge the lap with grinding paste - the sort used for grinding-in car engine valves - and run the lap in the lathe, sliding the cylinder backwards and forwards along it.  It needs a bit of care to address the risk of getting a hand caught.  It leaves a lovely finish.

Wilf

[Jasonb]

6 thou is a lot to hone off that small bore, I'd be looking at 1 thou maybe 2 thou at the most. I tend to use the sprung brake cylinder hones which are cheap enough buy are really only to take of the high and low spots left by the tool.

As this engine does not use rings I'd be more inclined to bore to 1thou under and then make a lap to use with fine 600g Silicon Carbide powder mixed with oil (Don't use valve grinding paste) and then lap the piston into the bore.

As for order of work I would suggest machining up the bearing caps then set them aside. Do the underside of the main frame and drill the mounting holes. Mount the engine onto a piece of plate and set it true to one edge of the plate which can then be used to clock things true and also gives you something easy to hold.

With a height gauge scribe a line at crank shaft height on the side of the lower bearing support and run that round to where the cylinder mounts too. Set the casting and it's plate up ay an angle and machine the tops of the bearing supports and tap the holes.

You can now bolt on the caps and bore them out at the marked position and then reset the work to face off the cylinder mounting surface which can easily be clocked 90degrees to the crankshaft,  drill and tap the cylinder mounting holes.

Then make the crankshaft followed by main bearings and flywheel both of which can be sized to fit the crankshaft.

[Admiral_dk]

Just in case you need any info on how to Make a Lapping Tool / how to use it - then this is one of the Reference Series here on MEM :
https://www.modelenginemaker.com/index.php/topic,1908.0.html

Per       

[john mills]

honing should only remove tool marks  we only left .0005" for finishing with a hand hone a rigid hone the stones mechanicaly forced out often with cones  or wedges,  the spring type should only remove glazed finish not to remove metal .i have only used a machine hone on a production line that .002" was left for honing  that was a big industrial machine with a hydraulic cylinder to drive out the stones.either machine the piston to fit or the bore would need to be set up and machined again .
John

[Jasonb]

In practice as most hobby users don't have access to rigid holes like Delapina, sunnen etc then the sprung type are used to remove metal as there will be no glaze on a freshly machined bore. They can even be used to take out a slight taper by concentrating the honing where the bore is smallest.