Kiwi Mk II

[vcutajar]

Congratulations Richard on a nice runner.

Vince

 

[Vietti]

Richard,

Very nice!!

An idea is to replace the oil drain with a one way check valve, the check valve is hooked up to the oil reservoir via a clear hose. Viola, you have a circulating oil system, don't forget to vent the top of the reservoir. Did it on a Wall 30, very similar to the Kiwi. Also if you ever decide to use a needle valve in your carb, be sure to get one with a Viton tip.

Congrats, a good working, small carb is no easy thing in my experience.

 

[Richard P]

Congratulations Richard on a nice runner.

Vince

Thanks Vince!

I feel like I've been following in your footsteps!

Time to start thinking about the next project...

Richard

 

[Richard P]

Richard,

Very nice!!

An idea is to replace the oil drain with a one way check valve, the check valve is hooked up to the oil reservoir via a clear hose. Viola, you have a circulating oil system, don't forget to vent the top of the reservoir. Did it on a Wall 30, very similar to the Kiwi. Also if you ever decide to use a needle valve in your carb, be sure to get one with a Viton tip.

Congrats, a good working, small carb is no easy thing in my experience.

Thanks! Interesting idea about the circulating oil system, I might have to try that!

Re your comment on the needle valve, did you mean in the float chamber? The steel needle adjustment into the actual carb seems to work fine.

Richard

 

[Vietti]

Yes, the needle I was referring to is the fuel needle valve controlled by the float. I made a carb that needed a needle valve and none of the ones I made or purchased worked until I got one with a Viton tip. I am assuming you are using the polished ball on a stem for a valve?

The oil system I described does work well and it is rewarding to see the oil moving back to the oil reservoir. Let me know if you have any questions.

John

 

[methuselah1]

Do you have any further details (even better, photos) of your recirculating setup, John? Did you make drawings, or was it a scribble pad job?

Andrew UK

 

[Richard P]

I decided to spend some time making a good quality stand for my Kiwi and ended up getting a bit carried away! The engine is quite tall and so I designed a quite high fuel tank based on some other examples I had seen online. I also designed and built a compact fuel tap around a couple of small viton o-rings I had spare. Pleased with how that turned out and it actually works and does not leak!

 

[Richard P]

I found a nice piece of thick off-cut walnut for the base of my Kiwi. I got it from a local specialist hardwood supplier in West London that supplies materials to bespoke furniture makers. I was able to mill out some neat enclosures for the Minimag ignition and battery to keep everything neat and tidy, and I turned up a nice thick brass washer to set off the inexpensive toggle switch! A short rod of polycarbonate allows the Minimag LED to shine through so that I can still set the timing. Almost finished...

 

[Steamchick]

My brother lined the cabin of his yacht with wood he "rescued" from scrap furniture. It is well seasoned after a lifetime in someone's house, so very stable from further warping with age. And a lot of the wood is fine grained hardwood. (Not like the softer Walnut you are using) - typically, Beech, Mahogany, Oak, Teak, etc. But the Walnut does have that curious, curly, knotty grain beloved of those who veneer it. Should look good!
K2

 

[Richard P]

And here a link to a Youtube clip of my fully finished Kiwi!

 

[Mike Ginn]

Guys
I am struggling!!!
I am trying to machine the Kiwi crank and so far I have failed to find the correct cutter. The picture shows the tools I have used all of which have an overhang of around 35mm. The tipped parting tools seem to "wobble" and I fear the carbide insert will spring out. The parting blade isn't really suited to the task and the tool in the rear tool post chatters badly at all speeds. I have cut a relief into the center of the cutting edge. I have tried the tipped parting off blade in the read tool post but it wasn't stable. I believe the tool height is correctly set.

I am sure it can't be that hard but so far I have failed to find a workable solution. I don't know the grade of the rolled mild steel but it came from a very reliable supplier some years ago and was used for general machining is a development model shop. I annealed it before use. It drills very easily.

Any insights would be appreciated.

Many thanks

Mike

 

[Steamchick]

Hi, I understand the problem. I have been there. 1/2" deep tools cannot cope with more than 1 in projection. So I used a tool blade 30mm deep x 4mm wide , clamped where the tool post would fit. Then I managed a stiff enough tool at 2 in projection to make it work. I'll try and set up some photos and sketches tomorrow.
K2

 

[phred]

I've not used it but have seen a supporting post mounted under the front end of the cutting tool to stabilize it in the vertical direction.
It might help solve your problem.
Fred.

 

[animal12]

I've not used it but have seen a supporting post mounted under the front end of the cutting tool to stabilize it in the vertical direction.
It might help solve your problem.
Fred.

I've seen some guys use a small machinist jack under the tool / holder . I wonder if using a big HSS tool might be suitable for a job like this , like a blank that's 1/2" x 1" . May have to make a tool holder but maybe having the mass in the tool will help ?
animal

 

[Steamchick]

Hi Mike, A toolmaker advised me that for a "proper" tool, to make a parallel big end journal, you need a tool ground like this:


Essentially:
It needs to be just less than the half width of the journal,
It is ground with a few thou or so or relief in the middle,
Corners are ground to make the radius required in the corner of the journal where it meets the web.

In use, a small cut is made, and the tool transited sideways across the full width of the journal and back, which ensures that the tool is cutting only a small side-cut, not a full face-cut.
This ensures that the most forward cutting point between the side radius and the centre relief forms a point contact at the tool and cuts across the journal to give a line of cut set by the alignment of the lather, not the precision of setting the tool. (if you had used a flat-fronted parting tool).

It generates the required radius in the corner, to relieve the natural fatigue stress raiser in the corner of the journal.
Incidentally, many single replaceable-blade parting tools have a tapered ground top face, which develops side forces and at the actual end where the cut is taking place the cut is "skewed" to the true line at which you want the journal to be cut for a parallel journal.
Hope this helps?
K2

 

[Steamchick]

Another arrangement of mounting a parting blade for a very rigid mount, is to clamp a parting blade on the back of the cross-slide for "reverse" running:
as per:

Hope this is clear enough?
K2

 

[Steamchick]

But the mounting/large parting blade I used was mounted like this:

I hope the sketch explains how I used a "huge" parting blade on my small lathe? - I removed the 4-way tool post etc. and mounted a suitable parting blade directly on the face where the tool post would mount, so I could get the right height of cutting point. My tool post takes 1/2" tool, but the blade was 30mm (or thereabouts) deep, and with a bit of judicious shimming I managed to fit it...
I had bought the Industrial sized parting blade in the £1 box at my second-hand tool shop - now long since gone, and missed!
K2

 

[Mike Ginn]

Guys - thank you for your thoughts. Unfortunately I can't use any form of jack since the space between the cheeks is only 1/2inch which is the same as the journal I am trying to cut.

Ken I really like your vertical cutter. I was proposing to purchase a 7/8 deep parting off tool blade but that would still have "fresh air" under it which would compromise rigidity. The cutter shown below could be cut to the correct length/shimmed and clamped which would really make for a solid setup. The forces would be directly down from the cutting edge to the cross slide and then to the carriage all of which is in the correct direction.

All my other cranks have been fabricated but with the oil holes I decided to take the plunge but I have to say I thought this would be easier then it is!

Many thanks

Mike

 

[Mike Ginn]

Ken
I have just made a few measurements and I can't see that there is sufficient space for clamps using the vertical configuration. There is just under 5/8 clearance between the journal cheeks and the cross slide. One solution would be to weld 2 pieces of MS to the tool and then tidy up the dimensions in the mill. The MS pieces probably need to be 90deg rotated from what the photo shows to allow for Tee bolt holes to be close together.

I still like the vertical arrangement but the setup will be tricky.

Mike

 

[Steamchick]

Hi Mike, I got the vertical blade idea from the web, so try a bit of a search to see if you can find it - and details of how it is arranged and clamped.
I have been browsing, and as an aside, found this "vee-notch" addition to parting tools that really works. I bought a parting tool with blade - that now lives in the back tool post - and the blade has a long Vee in it.
This video shows the "Quick re-grind" you can do to any tool you have...

K2