Clanford Clan 0.24cc Aero engine

[creast]

Thanks for the comments Barrie,
Although I am resigned to go the aluminium option (I have machined/fettled one at the moment), I will give your suggestions a try and see how it prints.
I did consider doing a lost PLA casting from the 3D print which is a technique I have used quite a bit and you can dress out the layer lines easier on metal.
I did look up the Ether/Paraffin resistance on Google and it indicated it was ok to use. I have just popped a sample into some fuel to confirm
Thanks for the note on CF filled PLA, I will check it out.
Cheers
Rich

 

[creast]

Quick update.
I just tried printing the part as Barrie suggested and it does show some promise apart from some weird print artifacts in a couple of places.
At this size the prints look reasonable by eye but as soon as you zoom in on a photo they look terrible.
I did try to print the M4 thread but the resolution of the printing is not really up to it (0.1mm layer height, 0.3mm nozzle).
It was easy to run a die over it though to at least size it a bit.
A sample of PETG has been in fuel for 3 hours now and shows no sign of distress. I will leave it a day or so to confirm.
I have also ordered a sample of the CF filled PLA to have a play with.

 

[Bazzer]

Rich

If you send me the model I will print one for you to see how I get on? I think it is optimistic to print the thread, I think I would leave that plain and run a die over it to create the thread.

The CF PLA from Proto Pasta can be heat treated to resist 150 deg C, I don't think the Clan will get to that temp on the intake side !!

Regards

Barrie

 

[creast]

Barrie,
Yes, I knew the printed thread would be a waste of time but hey, worth a try to see how the printer coped with it... not well LOL!
It's very kind of you to offer but as you see from the attached I have laboured away on the aluminium version which I hope to anodise black in keeping with the original (I know I'm not the first to go the alu route).
If however, from a curiosity point of view, you would like to try then I am happy to send you an STL or if you are a GrabCad subscriber you can find my Clan on there.
Cheers
Rich

 

[Bazzer]

Hello Rich
I have down loaded your Clan model and isolated the fuel tank cap.

Attached is a print of the cap, this was the second attempt, the first printed vertically had some drop out of detail due to no supports.

On the second print I layed the part conventionally and allowed supports under the flange where the fuel bulb sits and under the tube that screws into the engine.

Under the naked eye or mild magnification the part looks really quite good.

Clan_Fuel_Tank_Cap

• Bazzer
• Oct 1, 2019

3D printed Clan 0.24cc fuel tank cap

However you are a quick worker and the metal part you have made is far superior to a 3D printed part.

Regards

Barrie

 

[creast]

Barrie,
That's come out really nice!The print quality looks a lot better than mine.
I haven't refined the settings for PETG apart from temperature on my Anet A8 which has served me well for most of my requirements but is at the budget end of printers.
I have just received a sample length of the Carbon fibre PLA to play with which may suit other projects I have in mind.
Did you use standard PLA settings?
Also, have you sussed a workaround for restoring finish on sanded prints (apart from paint). Black always goes the proverbial grey.
Regards,
Rich

 

[Bazzer]

Hello Rich

I have used exactly the same settings with the CF PLA as normal PLA, I print at 220 deg C, with a 0.4mm nozzle and 0.1mm steps, I set a nozzle to bed gap of 0.075mm, for small parts I use 100% infill (solid), the printer is a Dremel 3D20 which my family bought second hand for my birthday.

I have only been printing with the CF PLA for a week now and to be honest all of the parts I have made have such a nice finish that I have not sanded them. I do know the greying that you mention from many other similar jobs. I would suggest that an easy thing to do would be to wipe the sanded surface with a medium viscosity cyanoacrylate adhesive (domestic super glue).

I tested bonding PLA with cyanoacrylate and it stuck like the proverbial you know what.

Regards
Barrie

 

[creast]

Thanks for info and tips Barrie, I am looking forward to trying this material out soon.

Today I spent the whole morning trying to make the compression screw. It took me five goes to get one!
The problem was partly that I was using silver steel and this doesn't like bending cold so heating was in order. However, this also led to poor bend radii on several occasions. All manner of problems where it just didn't look right.
In the end I machined 4mm dia mild steel down to size and annealed the bend during forming and voila!
At this point I couldn't resist assembling the engine and seeing if it would fire up without the carb (still under construction).
I was really pleased that after some time of just squirting fuel into the ports and endless flicking it did actually run for a second or two on several occasions. Encouraging indeed!
Some bubbles from the compression screw thread indicates the contra-piston is not tight enough (which I suspected) and so I will make new.
After that it's time to start anodising

 

[Bazzer]

I would be interested to know about your anodising setup? my anodising has been hit and miss, there must be something I am doing wrong.

B.

 

[creast]

Barrie,
It's been quite a few years since I did any anodising so it will be a revised learning curve.
The last time was the cylinders on my Ky-Ko sterling fan which turned out good. I used a commercial black dye then which I will use for the fuel cap.
The red is a new venture using Dylon fabric dye so fingers crossed. Obviously need to do some trials first.

 

[creast]

Today was Anodising day (evening really).
I wasn't sure if the acid I used years ago was any good but I set up the bath and did a test run on a piece of scrap.
The bath is just a plastic container with lead sheet as the cathode and aluminium rod to connect the part to anode.
Constant current of approx 100mA @ 15v for 1 hour.
All looked promising and the dye uptake with commercial black was pretty good so I went for broke on the carburettor cap and I am quite happy with the result.
Next was the red dye which was a fabric 'Dylon' dye which proved disastrous as it obviously wasn't being absorbed into the pores. I hurriedly gutted an inkjet printer cartridge and dunked the part into it.
Ok, its not red! It's magenta and the part is not the final spinner but it did show that inkjet dyes are a working solution so now I need to blend inks for the red. I also need to find a decent method to polish it too.

 

[Billitmotors]

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.

G’day Creast
When I made mine I machined the cap from delrin and then machined brass inserts which were assembled and then soft soldered in place. The biggest problem I found was finding brass tube small enough for the fuel intake and ended drawing it too the correct diamater using a drawing plate that I was given years ago and then having to drill it out using jetting drills because when you draw it through the plate it reduces the OD but the ID gets smaller as well.

 

[creast]

G’day Creast
When I made mine I machined the cap from delrin and then machined brass inserts which were assembled and then soft soldered in place. The biggest problem I found was finding brass tube small enough for the fuel intake and ended drawing it too the correct diamater using a drawing plate that I was given years ago and then having to drill it out using jetting drills because when you draw it through the plate it reduces the OD but the ID gets smaller as well.

I am impressed how well you managed to soft solder the parts in-situ, I have scrutinised your earlier photos you sent and am well impressed.
Also, re-drawing tube is another feat I have not ever undertaken. Great work!
I have chosen to use a hypodermic needle for my tube and finally chosen a glass fuel bowl cut from a test tube after underachieving a pure clear acrylic version by machining.

Rich

 

[creast]

Anodising part 2.
Blending magenta and yellow inkjet inks 50/50 and diluting 3:1 with distilled water has proven to be a good dye option.
5 mins immersion was plenty enough followed by steaming for 2 mins and boiling in deionised water for 5 minutes .
From research, the 6082T6 alloy is prone to dull anodising apart from the fact I didn't polish the parts but I am happy with the results.
The photo doesn't really do it justice and looks more like a paint finish.

 

[creast]

It took me two goes to get the correct fit on the contra-piston but it is much better for it.
The carb was finally finished and the engine is complete.
I hope to have her running soon.

 

[Bazzer]

Rich

Your engine looks really sweet with nice detail.

More than that I am impressed with how quick you get things done, great effort.

Regards

Barrie

 

[creast]

Thanks for the kind comments Barrie.
It does help that I am retired and I do tend to get a 'bee in my bonnet' on some projects.
Rich

 

[creast]

Update. The project isn't finished until it functions!
Three hours of flicking, priming and two propeller cuts later I think I am on track.
The engine would start fairly readily with priming through the exhaust ports but would only run a few seconds. Trying all the usual tweaks of mixture and compression didn't result in any improvement and I suspected the carb.
Luckily I found an old simple needle carb from an unknown engine and grafted it on.
Still not much luck!
In the end I found the engine would run if the tank level was slightly positive in head height and ran for over 3 minutes albeit slightly erratically.
To me this indicates either poor crankcase sealing or maybe poor venturi effect. I did seal the head screws into the case but maybe I need to check the rear cover and perhaps the cylinder to case sealing.
Having said that, the impromptu carb throat is probably too large but the one I made is definitely no good anyway.
Any ideas anybody?

 

[Maris Dislers]

To me this indicates either poor crankcase sealing or maybe poor venturi effect. I did seal the head screws into the case but maybe I need to check the rear cover and perhaps the cylinder to case sealing.
Having said that, the impromptu carb throat is probably too large but the one I made is definitely no good anyway.
Any ideas anybody?[/QUOTE]

Yes. Definitely ensure against crankcase compression leaks. Also ditch the spring under needle and replace with tygon or neoprene tubing to provide seal and the desired friction. The design choke size is OK, but could be a little smaller. If you have run the tap into venturi choke it will be oversize. If your thread for needle does go through, you could make a fresh needle with extra thread almost to the point where needle taper enters the fuel jet. This will block part of the choke and improve suction. With this style of carburetor, it's always better to lift the jet tube into the throat towards the centre, rather than expecting good airflow at the intake wall).

When starting mine, I find it best to just wet the piston at closed exhaust and use a syringe to add one drop, or perhaps two into the venturi. That should be plenty. Generous priming in the usual way will have you working on a false much lower compression setting that won't keep running. Go wit ha 6x3 propeller, which ought to bring RPM up to adequate speed for reliable operation. I run mine with equal parts ether kero castor oil plus .8% ignition improver. Tried same mix with mineral oil and it is less happy, but OK as an "after flight" fuel to avoid gumming up in storage. You might up ether to 40%.

 

[creast]

Maris,
Many thanks for passing on the hints, I really appreciate that.
Yes I did notice over priming did give some strange results and I will now revise my technique as suggested.
First I need to rebuild the engine and check all is sealed well and rework the carb.
It obviously can run so I am half way there!
Cheers
Rich