Hemmingway 5cc diesel engine build?

[911hillclimber]

Thanks for the kind words Jason, but don't look toooo closely!

[911hillclimber]

A few more hours today and a major (to me) step forward on this little project.

With my new drill sized for 'pre-reaming' the crankshaft bushes here drilled and reamed those rock 'ard bushes. This bearing material is a serious challenge to the machine tools I have, but got there.
This allowed at last the removal of the crank case from the 4 jaw chuck and onto the compound slide to machine the tricky bits on the case.

This all went to plan after a few hours of preparation a few days ago.
I made a close fitting mandrel and a stainless through bolt to screw everything tight to the vertical slide.

Managed to arrange the lot on the lathe's cross-slide to allow rotation of the casting and to mill the right surfaces starting with the engine mounting lugs before a very long thinking time before attacking the cylinder bore and more.

Made a pass or two on the one lug face (4 to machine) and it all cut well with very little chatter from the cross slide that (now) has near zero backlash (fixed 100 years of wear yesterday).

A few pics:

73T 911

[Dave Brooks]

I'm really enjoying following this build and the wonderful lathe! I have a pre-war Myford ML4 which I am getting to grips with. Great to see what can be achieved and I'm looking forward to seeing the outcome of this project. Keep up the good work!

 

 

[911hillclimber]

Thanks Dave. Much of this project is getting a 100 year old lathe to do this when it has no scales on the slides or controls let alone being a 'compact' design.

Some more for amusement:

 

Determined and productive day in the garage on this engine.

Wanted to finish the difficult machining on the crank case, the cylinder bore, the rod clearance slots and the transfer port plus the 4 tapped holes to retain the cylinder in place.

Nearly did it all. Just have to tap M4 the 4 cylinder holes and the 4 mounting holes for the lugs if this engine ever makes it into an aeroplane.

Had to make my own boring bar for the cylinder as i don't have the right size milling cutters or an adjustable internal boring bar, so spent 30 mins making one instead of spending and waiting for a 'real' one.

Few pics below. The surface finish leaves a bit to be desired, but a dremmel will sort that out. Big step out of the way, crank next when I've finished off the case and the cylinder details.

73T 911 Coupe, road/hillclimber 3.2L

[911hillclimber]

I'm a bit worried they are daily updates, but this project is keeping my tinkering spirit alive every day almost and getting obsessive much as my Lola build was.

Made some significant progress this afternoon in as much as actually finishing the parts so i can move on to the Big Challenges ahead.

Silver brazed the inlet stub to the cylinder that certainly blackened it!
That was followed by soft soldering the transfer porting cover to the cylinder as well, and that added to the scruffy look....

I last silver brazed/soldered back at school for my GCSE in metalwork which I got a distinction in (and Art). Those were the days.

The school was a bit off-the-wall in those days (60's) and there was an after school Club for all subjects, so I did metalwork where the game was to do anything outside of the curriculum, so we cast metal (!), brazed, and cut and made nice things.

I really wanted to be a jeweler as a career, but my father was not so sure (he was an architect) so i did a heavy engineering apprenticeship instead.

The crank case is all done, cylinder studs in and loctited and it all screws together!
Amazing for me and my skill base.

A few pics as ever, but I'm getting excited.

73T 91

[Engine Doctor]

Good to hear your re-kindling those school day lessons . We did similar things in metal and woodwork lessons .As you say back in the 60's schooling was totally different and did teach you many practical skills that todays students miss out on , hence the throw away society . Ironically for coming 1st in year.  I won a Stanley smoothing plane for metal work ! Still have it . They even taught us to sharpen the blades . Imagine that now !

[911hillclimber]

Another great few hours this afternoon on the engine.
Felt in the mood to start the crankshaft.
Big lump of En8, 3 1/8" long, bit of a tease to machine.

Has some inspiration to how to set the bar up to machine the crank pin 7/16" off centre to set the throw of the crank/rod.

Found my Vee blocks and clamp i made when 16 in my first year as an apprentice, and put faith in those parts being accurate (!)First time I have ever used them in 54 years.

The Vee block mounted well on the 4 jaw, the hold being really sound and stable and the final jaw clamped the crank bar 'blank' tight and the stirrup clamp I made back then secured the top. The pics say it all.

First few cuts were super light to test all is well. The mass turns as a blurr with almost no reference to the lathe to assure yourself you know where you are.

This is the mother of all intermittent cuts, and a bit nervy to say the least.

I have kept a check on the chuck jaw tightness!

Leaving the pin well oversize (it is 1/4" dia when done) and only 3/16" long.

This has perplexed me a bit since I bought the design, but seems to be working out so far.

A lot more swarf to generate yet.

73T 911 Coupe, road/h

[jeff2wings]

I would be careful with the cuts as you have very little engagement with the scroll on one jaw ,if the intermittent cuts are jarring the gears hard you can dampen the effect by using a piece of wood against the chuck, see page 4 of my thread

[911hillclimber]

Thank for the advice Jeff and it was something i worried about too. The jaws are all on the edge a bit.

I check their tightness every 4th (fine) cut.

I think I'm taking 10 though cuts at a time (no graduation on the cross slide so a guess)

 

I'll try the wood shock absorber technique too!

 

Will take some time.....

Edited March 3 by 911hillclimber

[RottenRow]

Ha ha I made the same vee block and clamp as a first year apprentice too. It must have been a standard EITB thing at the time.

 

At what speed is the lathe turning to make that cut please? I’m asking purely out of interest.

 

Would using the tailstock with a centre on the end of the crankpin add a bit of security, or is that a bad idea? Perhaps there isn’t sufficient room with the saddle and slides. Or perhaps you have just moved it back for the photos, as I can see it in place on the top photo.

 

A very interesting thread, thank you.

 

Brian.

[911hillclimber]

Thank you Brian, kind of you to say.

 

This project has been interesting for me beyond what i expected.

 

I think the Vees and clamp were indeed EITB as I made a marking out stand too, and a machinists vice, a Vee screw jack, a hacksaw, an adjustable pipe wrench and a tool box to put the lot in.

Also made a small vertical drill press (!) but the thing got stolen at the end of the year.

 

The Apprentice School closed after my year moved out....

 

No idea how i made all that lot.

The plan is to machine the 'centre' off on the pin area and then centre drill off the tailstock and have a dead centre engaged.

Pulled the tail stock back for ease of use and to calm my nerves! (and to take the pics)

 

Tricky to get the tool bit right up to the rod pin as the tool holder is a bit balky.

Edited March 3 by 911hillclimber

[RottenRow]

Thanks. All makes sense.

 

What is the speed of the chuck please?

 

Brian.

[911hillclimber]

No idea at all.

It is limited to a few pulley sizes and the V belt can't be adjusted to all of those, so the speed I'm using is 'one speed fits all'.

I think is is part of the issue of surface finish and depth of cut.

 

The motor on the lathe is not the strongest...

Edited March 3 by 911hillclimber

[RottenRow]

He he that simplifies things then!

 

Nice old lathe.

 

Brian.

[jeff2wings]

If you go on e-bay and look for myford accessories they sell a clip together belt,abit like the old motorcycle final drive belts before using chains,this should give you the chance of adjusting the belt length to suit

 

[911hillclimber]

Interesting!

Know the belt type you describe Jeff, thank you.

Going to try machining with HSS tip tomorrow, see if that is better.

 

If I speed the lathe up i loose torque and then the cut has to be even lighter. All this 'compromise' comes to play when cutting large diameters, around 1" or above the old lathe gets marginal.

 

Come down to 3/4 or 1/2" max dia and all is far better.

 

Still love this old lathe and these little challenges .

[Martin Harris - Moderator]

I’m thoroughly enjoying these postings, showing what can be achieved with some fairly basic equipment and ingenuity.

 

Although I went to a grammar school, we had a wonderfully equipped metalwork shop with, along with the ubiquitous Boxford lathes, much larger Colchester and Cardiff ones, several vertical and horizontal mills, surface grinder, shaping machine, power hacksaw, forging, welding and casting equipment - all of which which we were encouraged to use by an enthusiastic and supportive teacher with industrial experience - both during lessons and for various projects after school hours. 
 

Although I didn’t go into mechanical engineering, this grounding gave great basic skills to build on in later life in activities such as aeromodelling and vehicle  restoration and gave the impetus to acquiring some basic machine tools of my own which have been, and continue to be, so useful in a myriad of activities. 
 

Yes, we were exposed to dangerous equipment and the odd splash of blood may have dripped onto the floor, but safety was not only taught but enforced with vigilance, free from the shadow of formal risk assessments, method statements and potential litigation hanging over the school staff.  We, in turn, learnt to take responsibility for our actions - something I fear is not always the case with modern generations. 
 

Hope to see this engine running before very long!

[911hillclimber]

Well said.

My daughter, who is approaching 38 now did Resistant Materials, an amalgam of metal and wood work. She took to it well but when things broke at her local school they stayed broken, never fixed, so the practical side disappeared quickly.

She now works in property and is restoring a house with her husband who has trained her in nail gun use to polyfiller...

 

Hope it warms up today so I can get back on the crank this afternoon in the garage, flippin' cold out there!

[911hillclimber]

Had a hard few hours in the garage on the crankshaft where I sort of managed to dodge a bullet.

First, surface finish and tools.
Tried a new tip, cuts well for 4 passes on En8 and feels dull after but still cutting.
Tried HSS on the same material, no difference just so hard to shape the tip on a small grinder. With a good tool form results may have been better (?)

Raised the lathe spindle speed to roughly 2 x the normal speed.
Cutting much better using a fresh tip, but the belts are too tight and the head stock bearings were getting hot!

Back to normal speed and light touch.

As to the bloody crankshaft pin...
All was going well right down to about 10 thou over the 1/4" pin diameter and suddenly the tool dug in, stalled the lathe and put a deep gouge in the pin AND rotated the bar in the chuck so loosing the pin position, just about the worst thing that could happen at this stage.

Got the pin roughly back into place, but the pin still eccentric no matter what I did, so with it around and about right decided to carry on turning the pin until it cleaned up.

This was, of course, below 1/4" dia BUT smack-on 6 mm so the con rod will have a big end dia of 6 mm and not 1/4" and we shall see what happens.

Crank now back in the 3 jaw and busy machining down to 5/15" dia, lots of swarf.

Day off tomorrow which may be just as well!

73T 911

[jeff2wings]

Yes you did doge a bullet there, lucky not too have it disengage from the chuck and damage it and more to the point, you!! Mounting the workpiece securely is paramount for safety and accuracy,also if you had machined the shaft (oversize) first it would have reduced the excessive jaw over hang.Also increasing the rpm is exactly the opposite of what you need to do to improve the quality of finish, a mistake most beginners make when starting out,myself included! I would recommend talking a step back and sort out the basics of work holding, tool grinding and getting the lathe running at the right speed range,you're up against it using a 100 year old lathe as it is(and good on you for doing so) 

three crankshafts produce a lot of swarf

[911hillclimber]

Every day is a school day!

The tool dug in as I was cleaning out the radius of the pin to the crank web trying to get the rad to = the tool tip rad.

 

It is not too bad, a big end 6 mm v 0.25".

I wonder about removing the machined pin and drilling/ream a 5/16 hole and make an En8 pin to fit and braze it all then set=up and machine the inserted pin to 1/4", but a lot of messing about.

I'll need a 6 mm reamer now if I stick with it.

In hindsight, I should have machined the blank down to around 5/8" and put that in the Vee block which would have tucked the two jaws in tighter, but we are where we are!

 

I plan to machine the crank to 5/16 to suit the bushed reamed to that size, An hour should have that done.

 

The lathe on it's lowest speed and the tipped tool machines badly. An old lathe but all I have!

Feeling a bit dispondant at the moment, but tomorrow is another day.

[Dave Brooks]

Looks as though you're making good progress. Its easy to get frustrated, especially using less than perfect tools, but as you've said yourself, that's partly what this project is about. Its looks easy to do this on an high end machine with perfect rigid set up, but how many have that luxury? Even if you'd ruined that part, you've clearly learned enough to have a better chance of success next time round.

 

I quite like that if something doesn't go entirely to plan on my small old lathe, typically the drive belt just slips without too much further drama! I think that back in the day these machines could be powered by a treadle arrangement which looks fun and might provide some variable speed capability! The idea of machining with no mechanical assistance does appeal rather. I think my approach is similar to yours in that on an old machine with no gradations you have to proceed by 'feel' to some degree and understand what the machine is capable of for different materials and cuts etc. 

 

I'm learning much here and am in danger of being inspired to have a go too. I've been looking at the Boll Aero 18 and have most of the materials ready to go but not quite the confidence that I can achieve the required accuracy with my set up just yet! Looking forward to seeing how you tackle the piston/bore elements!    

[911hillclimber]

Thank you Dave, just the kind of post I expect on this great forum which I've used a LOT to get me over my model flying pains!

There is a spark ignition engine on Hemmingways which I really fancy next....

Hemmingways are only 20 mins from me so can get another bar of En8 from them and do the crank again to drawing, but would braze an 8mm fresh pin in first and machine the over sized pin to 1/4" dia first.

 

But this one first. Back from a nice sunny drive/visit to Ludlow today and some safety glasses i can actually see through.

 

Seems I need them. (LOL)

Edited March 5 by 911hillclimber

[911hillclimber]

A bit more of a tease doing the crank shaft this afternoon.

The crank is not co-operating at all. Slowly machined the shaft down to 5/16" ish using the tipped side n face cutter, new for the hacking down stage, then a fresh tip to get to a size that gave a nice running fit in the reamed bushes. That sounds easy, but was a sod to do, but now have a crank that fits into the case.

However....

The pin that I just about managed to save and now 6 mm dia is in the wrong place.

 

The throw is too large. I have obviously set the 7/16" throw to far or have crank case diameters too small or both.

 

The clearance from the pin to the rear cover thread to far too small.

 

Will measure tomorrow, but on the face of it would demand a big end con rod wall thickness of a mere 1/13", it should be 1/16".

 

So, what to do to fix this?

 

My thoughts are to remover the machined pin, and drill  for an oversized pin,  braze it in and machine the pin to a stroke less than 7/16", more 3/8".

 

At this stage i have nothing to loose but to try it all and see if I can get it work.

IRRITATING.

[Martin Harris - Moderator]

How about drilling/reaming a hole in the correct place and pressing in a 1/4” bearing roller?

 

Different lengths available…

 

https://simplybearings.co.uk/shop/Loose-Balls-and-Rollers-Loose-Steel-Rollers/c23_5043/index.html?selection=Loose+Rollers