Posts tagged: edit-later

May 27 2010

New MkIII benchtop degasser

So I’ve finally managed to get some bits together and assemble the new smaller degasser.

I used the fire extinguisher from the MkI degasser, which I cut shorter. Sadly it’d been out in the rain, as well as having been used for degassing previously.
Even sanding it heavily obviously didn’t remove all the traces. I used a nice zinc primer on the inside which seemed to take, but once I went over it with white enamel it refused to bond where the resins had previously splashed.
Next time I’ll fork out for some Hammerite. I’m not even sure this enamel will survive cleaning any spatter off the inside later.

Found that Poundland is doing rather large tubes of two-part epoxy! Handy stuff to have around. Especially for £6 cheaper than Araldite. It does reek of fish before it sets though.
The 99p Shop nearby provided a cheap frying pan which got cut up into the lid surround. Fitted so tightly there was no need for a retaining pipe-clip strap.

I brazed a load spreader to the UTA manifold, and glued it on. The nossle holder of the extinguishers base perfectly holds the up-to-air filter so it’s a ready-made support. Without it I’d be worried about the lever-handled ball-valve dislodged the manifold after only a few uses.

Made a proper handle from some curved extruded aluminium and some bolts. Again, glued onto 10mm polycarbonate cut to size. I’m unsure if it’ll need internal lighting yet. The white inside reflects a lot of ambient light and it’s not as deep. Will see.

So I now have a nice small degasser for using on the workbench! Both controls are nice easy to use lever-handled ball valves. I should be able to leave the pump running to the catchpot and simply switch the two valves for fast control.
It should make the degassing of the resins prior to pouring them far simpler. And if one is sealed under a static vacuum, the other chamber can be used under pumped vacuum.

One thing to note is that it looks messy because the Poundland 131 epoxy is thinner and slower-setting than Araldite. But if it works, it works, and it seems just as strong when set.

As another improvement to the system I also mounted up the MkII chamber, pump and catchpot to a plank of wood. It reduces the footprint a bit but mostly stops them from moving around in use and flexing the pipes which can result in leaks or manifolds breaking.

Will try to get a short demo video up on youtube.

[20/06/2010: Amalgamating old posts from “Dreamwidth Creative Blog” into sci-fi-fox.com to re-purpose DW blog account.]

May 27 2010

Buster: Car and batteries examination

So here’s the lil fella I picked up for £3..

This little mock quad-bike is pretty lightweight. There’s some metal framework for the axles, but the rest is all a moulded plastic body. I’d be worried about it taking the weight of extra parts if it wasn’t designed to cart around reasonably large children.
The rear drive wheels are pretty worn, and all are the cheap hollow plastic variety.
They’re a lot wider and with less grip than the ones on the original Buster’s frame as best I can judge from the few photos. I’ll keep it in mind as it may have issues with drive and steering.

The rear wheels have separate drive motors, driven together on a static axle. Cheapest design, but running the motors together should be fine.

Controls are pretty simple. Two sealed 6v lead-acid batteries, a two-button toggle for forward and reverse, another for fast and slow (seems to switch the batteries from serial to parallel connection, so 6v to 12v) and a foot pedal switch to make it go.
The controls on the handlebars are purely for show. There’s nothing in them beside a horn powered by a separate set of AA batteries.

I should be able to strip off a few odds and ends, but as it’s a monocoque they’ll be a limit. And since I’m running out of space here, my Buster will need to be able to be stored outside.
I suspect the control electronics may be a bit smaller, even using as close to 1970s parts as I can. Maybe if I upturn a plastic bin on them that’ll be sufficient rainproof housing.

I was quite excited to find it used two 6v batteries, as that’s what Buster was designed to run on. However when I measured them they only read 2.27v each.
Lead-acid batteries are also not meant to be concave.

My charger wouldn’t read it as needing the charge. Rather wish the charger gave out more information on battery status. Charging complete has the same indication as being unable to charge.

As a last-ditch effort I pried the sealed cover off one of the batteries and found three rubber caps. On pulling one off there was a characteristic sucking noise. All the cells were under vacuum. So I suspect the car may have been left out in hot sun for a long time, and literally boiled the batteries dry. So when they cooled the covers were sucked on.
With nothing to loose I grabbed a bottle of demin water and proceeded to refill the cells with a syringe through the tiny vent holes.

Sadly, that didn’t work. Even after a few days for the plates to re-wet, the readings didn’t change at all. Due to construction there’s no way of getting electrolyte back out again to check the gravity. At this point though it’ll just be simpler to spend the £20 buying a new set of more powerful batts.

[20/06/2010: Amalgamating old posts from “Dreamwidth Creative Blog” into sci-fi-fox.com to re-purpose DW blog account.]

Apr 28 2010

The Answer is 42

42 new shirts arrived today in record time (just 2 working days after I ordered them!). That gives me 4 of each size of both the UKFur Classic/Wolf shirts, and the colour “Union” design. There’s been little interest in the dragon shirts, so haven’t picked up any more of them for the moment.

If I run out of any at the con I’ll take pre-orders for the next batch.

Okay, now back to the workshop!

[20/06/2010: Amalgamating old posts from “Dreamwidth Creative Blog” into sci-fi-fox.com to re-purpose DW blog account.]

Apr 26 2010

Heh!

Looking through the old story ground files I compiled for reference. The station I created for it back around the year 2000, Outpost 1..

Suddenly a memory comes to me of the more recent trailers for Mass Effect 2..

It’s only a rough likeness, but it’d be nice to think the group had a fan in BioWare. ;)

[20/06/2010: Amalgamating old posts from “Dreamwidth Creative Blog” into sci-fi-fox.com to re-purpose DW blog account.]

Apr 22 2010

Get angry and build robots. Part 2.

More tinkering today.

Pulled the frame apart and flipped it over to give the motors more ground clearance and enough space for a trailing castor.
Rather than cut up the push-scooter bearing tubes, I made a new longer one from a piece of old vacuum cleaner nossle and bolted it into the clamp from an old satellite dish mount. That gave me some bolt holes and nice steel plate to attach some more scrap 1″ box section to as an angle-block. Another couple of bits of smaller box-section went on top again to provide rigidity.

I’ve run out of M6 bolts now though, so will have to get some. Studding would probably be better though.
The motor assemblies were already made up, so it’s really only the frame that’s the product of the last couple of days.

The motors look a little wonky because they’re not bolted down properly. Neither are the bearing-blocks, which’ll need three more M10 carriage bolts. Probably want to put some fibre washers between the motor mounts and frame to help prevent damage to the aluminium gearbox housings.

Here it is with the existing battery box roughly in place.

It’s a large box because it contains a commercial van battery (12v, Lead-acid), as well as positive and negative bus-bars, keyswitch, automotive fuse panel and emergency-stop button on the rear hatch.
May had a high-current plug to it too to allow it to provide jump-starts. If I find one of them laying about anyway.

No motor controllers as yet. I still need to test the stall current of the motors (12v, 180Watt, ~220rpm geared).
Wheels are ten-inch pneumatic sack-barrow wheels. Freewheeling hubs were previously ground off and fixed hubs with a coupler-dog brazed up and bolted on.

Got some aluminium car-phone enclosures with surface-mounting holes that should take a controller each quite nicely.

Whatever this ends up being, it’ll be pretty powerful and be able to go a long way.

Need to make mounts to secure battery box and fork-extensions to turn the current front wheel into a castor. Wanted a pneumatic castor, but there’s not enough space under the frame currently. Maybe later.

Will keep my eyes on the river; see if a shopping trolley turns up. A trolley basket could be a good addition to it for the moment.

[20/06/2010: Amalgamating old posts from “Dreamwidth Creative Blog” into sci-fi-fox.com to re-purpose DW blog account.]

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