New Tools

[peterd51]

Hi Guys,

first a great big 'thanks' to Weldequip...

I ordered an auto mask, regulator & argon adaptor late yesterday afternoon and it was delivered this morning!

Brilliant service.

So I had this little job to make a manifold to fit a new Jettex carb, as used on Lambrettas, onto the hovercraft engine (being a Rocker from the '60s it hurts to use something off a tea-trolley!).

I've bought a few tools over the last few months...as well as the gear from Weldequip I got a lathe and a plasma cutter a few weeks ago and this little project allowed me to use most of them.

I found a bit of pipe that was around 2.5mm too big for the carb and used the lathe to thin about an inch at one end.

Then I used the plasma to cut the flange out of 3mm plate.

Finally I got the chance to use the new regulator, with a flow meter (not had one of those before!) and the new auto mask (really nice) if only for a few seconds.

Someone mentioned in a previous message about the 'sound' of welding...

I can hear the difference with this new regulator, it was a really nice fizz without the 'popping' I had from the old one!

Anyhow, here's the manifold...



as an idea of scale, the bit of box it's propped up on is 20mm.

Regards
Peter

 

[rusty69bus]

bet you've that warm feeling now, it's feels good to make something from sratch...well done

 

[bawjaws]

it hurts to use something off a tea-trolley

WE ARE THE MODS, WE ARE THE MODS, WE ARE WE ARE WE ARE THE MODS!! -anyway, good job!

 

[drivewasher]

My grandma used to shorten my trousers on a machine with a carburetta like that! lol..

 

[inchpincher]

Hey, less of the tea trolley! (As a scooterist i prefer Mikuni carbs anyways ).
Nice little project but if you're not careful the hovercraft won't be safe from the Lambrettas!

 

[peterd51]

Hi,

hmm, I can't see how that water scooter was being driven by the rear wheel...

surely there'd have been much more spray?

Anyhow, this is a temporary fix to do some basic safety testing on the hover.

If it works then I plan to upgrade to a Kawasaki 500 and a bigger fan for next summer.

It'll be quieter than the 2-stroke Kohler engine, more reliable, and use a lot less fuel.

Regards
Peter

 

[Robotstar5]

If it works then I plan to upgrade to a Kawasaki 500 and a bigger fan for next summer.

Don't mess about - stick a V8 in it!

 

[scotb]

v8

no,not just any v8- a big f**koff v8!

 

[malcolm]

no,not just any v8- a big f**koff v8!

You've been watching Marks and Spencer adverts haven't you Good point though - why waste time with weedy ones when there's a 700hp Chevvy on the market for only 15k.

 

[peterd51]

Hi,

the fan will only absorb a set amount of HP and anything over is wasted/not used.

Plus there's a balance between output power and weight.

My current engine is 28kg and develops about 14HP. A Kawa 500 is twice the weight but three times the power out.

/But/ the current fan can't handle 50HP and needs to stay running at the same speed so the extra power is wasted and due to the extra weight the hover runs slower. So I need to increase the size of the fan, which means a bigger duct, which is more weight and more air resistance.

It's more of a balancing act with a hover than with a car or motorbike.

As well as working with engines, hovercraft involves plywood, glass fibre, alluminium, mild steel and nylon for the skirt (I have a nice little electric sewing machine that I've converted to manual for delicate work). Then there's static and dynamic pressures, air flow, etc, and a bit of aerodynamics on the fan blades.

Plenty to think about...

But I got the carb on the engine yesterday. Needed an air-filter so had a wander around the local car-boot. Found one off an old motorbike, no idea what it is, but it works and it only cost 50p!

The Jettex choke is a simple thing...a spring forces a stop over a fuel port. Lift the stop and more fuel flows through the carb. I didn't have a cable so I cut a bit of 4mm thread about 5mm long, drilled a 1mm hole through it and soldered a length of mig welding wire to it.

To open the choke I pull the wire up and clamp it to the engine mount with a market stall clamp.

Had the engine running smoothly in the workshop, nice tick-over where it was drifting all over the place with the old carb.

The engine's in the hovercraft now. I need to find a Lambretta choke cable plus lever and a 5 foot long throttle cable (probably email the guys I bought the Jettex off, they restore Lambrettas) and I should be able to test hover it on the drive next weekend!

Regards
Peter

 

[peterd51]

Hi,

just a follow-up to show what happened to the manifold. I have a big bag of old gaskets, oil-seals and bits of cork off various cars gathered over the years. I found a gasket off something or other that was pretty close to what I needed. I just had to widen the centre hole slightly and clamped the manifold in place, then attached the carb...



I needed a choke cable & lever but couldn't find one anywhere. Too expensive on ebay, and local bike-breakers don't seem to understand words like 'adapt' and 'choke-lever'...

"What's it for", they ask, and I reply, "a hovercraft", and they say, "ah, don't know anything about them".

So I had to make one. Basically it's a bit of 3mm x 20mm bent at 90 degrees, one leg is about 25mm long while the other is about 40mm. I drilled holes in each flange and on the long one I attached a washer with a nut and bolt with a locknut.

Then I welded a piece of 3 x 10mm to the washer to make the choke lever (is it just me or does this weld look like a crouching rabbit!).



I folded another piece of 3 x 10mm to 90 degrees and welded that on to hold the outer sheath back when I operated the inner. Here's the finished choke lever bolted onto the fan-guard.



the cable is attached by a small bolt with a hole it in and I just clamp the cable with a nut. To get the right amount of friction I cut a circle the same size as the washer out of an old plastic ice-cream tub and that sits between the washer and the bracket.

It all works and I had the engine running for a short time today but it started to rain before I could test-fly the beast up the drive.

Maybe tomorrow!

Regards
Peter