Clanford Clan 0.24cc Aero engine

[creast]

Hi Guys,
Its been a very long time since I did a build log (last was the Vega V-twin) but I have decided to for a simpler but probably very challenging go at the Clanford Clan.
This is from the 'Motor Boys' plan book and looks a real cutie!
I have created a 3D model to check out the plans and is posted on
https://grabcad.com/library/clanford-clan-0-24cc-aero-engine-1

First bite is the crankcase (pics to follow)

Has anybody here built one?

Cheers
Rich

 

[rklopp]

I built one. It is one of my favorite “diesels,” and I have build guide a few. It starts and runs quite easily.

 

[Billitmotors]

Can I make a suggestion . The crankcase has a small counterbore to align the cylinder and there are only two screws to hold it all together .
I would put a small stepped flange at the bottom of the cylinder to give a better bearing or sealing area. I found it very difficult to tighten everything so it didn't leak crankcase pressure.
Also don't let your screw holes break through into the crankcase, again, loss of crankcase pressure.
Good luck with the build.

 

[rklopp]

FWIW I did not have problems with crankcase leaks. I made my own screws, which probably fit tighter in the tapped holes than commercial screws. I may even have single-pointed them; I forget. The cylinder-crankcase joint should not leak provided the fit is snug, the surface finish is decent, and no burrs or chips are caught in the interface.

 

[creast]

Thanks Guys,
Any information/experiences would be most useful.
I just started machining the crankcase.

rklopp, your engine looks lovely! What did you make the fuel tank cap from?

 

[creast]

Can I make a suggestion . The crankcase has a small counterbore to align the cylinder and there are only two screws to hold it all together .
I would put a small stepped flange at the bottom of the cylinder to give a better bearing or sealing area. I found it very difficult to tighten everything so it didn't leak crankcase pressure.
Also don't let your screw holes break through into the crankcase, again, loss of crankcase pressure.
Good luck with the build.

Lovely looking motor!!!

 

[creast]

Well, today I started on the crankcase from 6082 T6 bar stock.
Its a long time since I did any thread turning on my ML7 and the tipped threading bar I had just cleared the bore. I think it has gone OK and wish I had turned a male thread part first! Oh well, will make it fit
Transferring the chuck to my rotary table is a first now I have a Myford adaptor plate. However, my mill, which is a Dore Westbury, had to have its head cranked high so I could run a DTI in the chuck and once set you can't move the head up or down without losing alignment. This meant rigidity was poor due to the head height.
Anyway, I have roughed out the profile and will square up the lugs later.

 

[rklopp]

Thanks Guys,
Any information/experiences would be most useful.
I just started machining the crankcase.

rklopp, your engine looks lovely! What did you make the fuel tank cap from?

The black part is Delrin (might be generic acetal) and the clear part is acrylic.

 

[creast]

The black part is Delrin (might be generic acetal) and the clear part is acrylic.

Can you tell me how the two are joined? Are they glued?
Also, I see two holes in the top of the Black Lid part which I am guessing are for filling and breathing. Is the larger hole plugged when in use?
Thanking you in advance . Rich

 

[creast]

Today I squared up the mounting lugs and drilled all holes. I decided to go M2 rather than 9 B.A as its close and the fasteners are more readily available. Plus I don't have a 9 B.A tap!
The bore and recess detail are 7.5mm dia and 8.5mm dia and I don't posess either drill or end mill of these sizes so decided to make a turning fixture to allow boring of these details which will be more controllable anyway.
Its amazing how much time is involved just hold things!

 

[rklopp]

Can you tell me how the two are joined? Are they glued?
Also, I see two holes in the top of the Black Lid part which I am guessing are for filling and breathing. Is the larger hole plugged when in use?
Thanking you in advance . Rich

The fuel tank and top are snap-fit using a little ridge and groove arrangement. The holes are indeed fill and vent. I do not plug either one when running. This engine has not flown and probably never will, so I have no concerns about spillage.

 

[creast]

The fuel tank and top are snap-fit using a little ridge and groove arrangement. The holes are indeed fill and vent. I do not plug either one when running. This engine has not flown and probably never will, so I have no concerns about spillage.

That sounds like fun?? Can see plenty of trials to get that fit right.
Oh well, all to be tackled later
Thanks!

 

[creast]

Progress has been slow due to other household work requiring attention and will be robbing me of my "playtime" as my other half refers to.
Anyway, despite promising myself to do all the aluminium bits I made the cylinder head and the spinner before diverting to the crankshaft.
Having just checked, I realise my spinner is probably wrong to drawing but I may stick with it anyway (senior moment I think)
I chose to use EN24T for the crankshaft as this is a strong alloy steel but I really struggled to get a got finish. In the end I used my DIY toolpost grinder of sorts to near finish the shaft and finally polish with 1000 grit abrasive.
The fit is still a little tight but can be tweaked later.

 

[creast]

Well, after another excursion, I am back to creating 'swarf'
After roughing out the cylinder in EN1A steel, I silver soldered the inlet port to it and machined in the ports.
With hindsight, I think for a future build I would silver solder onto a near finished bore and then trim the lengths to suit before machining the ports.
Lapping has resulted in a slight oversize of the specified bore but I will, hopefully, match the piston to suit.
Machining the backplate was a bit tricky and threading was actually done by rotating the chuck by hand as the undercut runout is very tight!
To produce the slot for tightening involved making a custom cutter as I didn't have a 1mm mill or circular cutter. I actually used a 1.3mm drill shank and it worked fine... only 0.003" cuts!

 

[creast]

It seems I haven't achieved much this week.
I have finally made the Con-Rod, piston and contrapiston and not without much pain in the process!
As I have said previously, most of the time is in making fixtures and custom tools to actually achieve all this.
I did not posess a 1.5mm reamer for the little end details so had to make one from a drill shank (See Clickspring on YouTube for details)
Lapping of the cylinder took many hours but I think it's ok. Slightly tight but I followed Ramon's method using a copper expandable lap.
On a trial assembly I have noted the con-rod fouling on the crankcase opening or maybe the cylinder and on checking the CAD model I can confirm that to be the case so I will have to take a little more off the con-rod cross section to about 2.8mm rather than 3mm.
Addendum- Since reading Mark Lester's build notes I can confirm this interference has been noted before.

 

[creast]

Today was spent modifying the chamfer to 40 degrees in the cylinder base to gain more clearance as with reducing the con-rod thickness .
I ended up wrecking the cylinder head when drilling the two screw holes as my DRO gave a false reading. Grrrr!!
Two tries later I managed to finish a new one and a trial fit showed all is well.
This is a more finicky job than expected!
Next is the carburettor.

 

[creast]

I have been waiting a while for a delivery of clear plastic test tubes from China which I hoped would enable me an easy route to the fuel bowl.
My hopes were dashed a little when they arrived. They were 12 mm OD at the top but tapered to just over 11 mm at where I wanted to part them off. They also had a change of section witness line at the bottom.
Even worse was they were quickly attacked by the fuel. Time to re-think and maybe I will have to machine one afterall!
I also 3D printed the cap hoping that may be acceptable. The original was an injection moulded part and I wasn't too keen in being able to machine this from solid Delrin due to the complex cylindrical blends. However, the layer lines look naff and they are a nightmare to sand out at the best of times.
So... This may be described as 'being a bit anal' ... I am going to have a go at DIY injection moulding the part!
I have made a 4 piece simple mould and am now making an ad-hoc extruder/injection tool. I plan to use PETG as this appears to be resistant to Ether and Paraffin etc. (To be continued)

 

[creast]

Well, it's been a frustrating couple of days.
My first attempts on injection moulding were plagued with poor fills and difficulty removing the moulding intact.
Then the thermocouple failed...aaarrrrgggh!
I had hoped the shrinkage of the plastic would negate the need for draft angles but was wrong. Coupled with the aluminium tooling needing pre-heat, this shrank more than the plastic.
So, I reverted to a PTFE mould and crude trials were very promising.
A mould was machined close to that of what is required and I couldn't resist having yet another go straight off to see if any problems lurked.
The design is not necessarily final and would require the part to be finish machined as would the bores etc as I fear I would never get any inserts back out!
The extruder is made from modified plumbing parts and a simple hand plunger mechanism. A 125W band heater does the heating.

 

[creast]

After a break in Spain I returned to the problematic carburettor cap.
Injection moulding was encouraging but not the answer. The threading of the PETG plastic for the manifold thread was simply awful.
There was also the weakness of the M2 thread for the needle valve so I regret I have to diverge from the plans.
I did try moulding with an insert thread for the inlet manifold but I was still not happy.
I admire anyone who has machined this part in plastic or even metal! Its a pretty awful shape and size to tackle as one piece.
So..its going to be in Aluminium and I really believe this is a best option since diesels can get pretty hot and I did fear for the plastic thread.
I have included a couple of the last moulding pics just for historical purposes.

 

[Bazzer]

Creast

An interesting project and some nice work to produce various parts.

With regard to the carb cap , did you consider printing it in a vertical direction? Maybe make a sacrificial base where the cap fits to the engine to give stability on the printer bed.

This way you would only be left with significant lines on the bowl diameter which would be much easier to clean up. The lines on the tube above the bowl in your photo would be tricky to clean up nicely.

Does PLA melt with ether and parrafin? If not you should try the CF filled PLA from Proto Pasta, it gives fantastic results and can be heat treated to resist approx. 140 deg C.

Regards

Barrie