The Bucket Foundry

[ken seeber]

BRAKES/FOUNDRY: Out with the old (drummies) and in with the new (diskies). For karts, we do an aluminium disc, hypereutectic, 16 – 18% Si. These are designed to replace the once very common CI types of Ø200 and 12 thick (428 gm compared to 966). We cast these horizontally. To get the mould to fill we actually spin it. Not really centrifugal casting, but maybe call it spin casting. One pic shows a casting that was done without spinning, resulting a very incomplete fill.




MM: We had a think about your machining and consider the swarf build-up on the cutter is applying too much lateral force on the fragile wax fins. So one way that might help is to do a double pass cut at each level. This would leave the majority of the cutter clear on one side, giving room for the swarf. The other option might be to drill vertically in very fine steps, doing a lot of peck cuts, maybe even offsetting as you go. Hope the pic makes some sort of sense.

[Michael Moore]

Ken, thanks for taking the time to think about what was going on.

It was fine all the way above that point in both X and Y axes, and the stepdowns on the taper mill were .012". It was fine motoring along parallel to the fins at faster feeds, but suddenly the corners at that low level were a problem (hey, that sounds like road racing!) There was an air blast clearing the very powdery wax swarf so there was no accumulation at the time things started breaking. The larger chips on the table were from roughing with .5" and .25" flat-end mills, not the taper mill.

The radius at the bottom of the fins is .125" (1/4" ball mill, 1 degree taper). With the fins being 2.25" tall flex gets even worse if I drop to a very long smaller mill. There's going to be a full slot at some point no matter what.

I drilled horizontally instead of vertical plunging to help the zero SFM tip of the ball mill have an easier time by having most of the material being removed to either side of it. Also, I was cutting the slot with a 1/4" flat end mill and then following with the taper mill to the same depth, so most of the cutting in the slots with the taper mill was on the sides, not the tip.

At the level where the fins broke they are 3/16" thick. I took one of them (1.5" long) and it was very easy to snap it in half with my fingers.

I'll give it one more try, this time finishing those 5 pockets and the fin ends in them first, and then complete cutting with the parallel runs to cut the fins apart. That will have the vertical ends with plenty of solid support next to them compared to cutting across a "free" fin.

But if that doesn't do it (wish I'd thought of doing it that way the first time but I got focused on making fins and not on finishing the ends) I'll go for a sturdier material cut with the second set of operations to give it the best possible chance of survival.

Were you having the aluminum rotors coated? I've got a Hunt plasma-sprayed rotor around somewhere, and I talked to Langcourt one time about having my Bultaco Sherpa T hubs nikasiled in place of the peeling chrome plating. They told me they'd done some nikasil-coated aluminum kart rotors for a customer and they worked pretty well.

cheers,
Michael

[Flettner]

Ok, hydro forming chambers. Read the book, saw the film, now had a go myself. Only did a header pipe at three degrees being oval from the cylinder to round. Used a water blaster @ approx 2000 psi. Now I would show you the results as the pipe formed beautifully but I can't bring myself to show the welding. I use bifocal lenses now and it seems I should be wearing them under the welding glasses, I can't $%^*(*&^ see!
Made new anvils for my 'dishing machine' to form the edges of the cut out sheet, this too I could show you but health and safety might be watching
Unfortunately this result is just too encouraging, I would like to just immerse myself in chamber making for the next few days BUT I have to work at that real job again
I'm just off out to the shed to try the bifocals, maybe I can get bifocal welding glasses / lenses?

[Frits Overmars]

Ok, hydro forming chambers. Read the book, saw the film, now had a go myself. Only did a header pipe at three degrees being oval from the cylinder to round. Used a water blaster @ approx 2000 psi. Now I would show you the results as the pipe formed beautifully but I can't bring myself to show the welding. I use bifocal lenses now and it seems I should be wearing them under the welding glasses, I can't $%^*(*&^ see!

I tried varifocals, could not get used to them. Now I just take my -3 glasses off when welding. Without them I have 20/20 vision all the way up to 50 cm away.

[Ocean1]

Ok, hydro forming chambers. Read the book, saw the film, now had a go myself. Only did a header pipe at three degrees being oval from the cylinder to round. Used a water blaster @ approx 2000 psi. Now I would show you the results as the pipe formed beautifully but I can't bring myself to show the welding. I use bifocal lenses now and it seems I should be wearing them under the welding glasses, I can't $%^*(*&^ see!
Made new anvils for my 'dishing machine' to form the edges of the cut out sheet, this too I could show you but health and safety might be watching
Unfortunately this result is just too encouraging, I would like to just immerse myself in chamber making for the next few days BUT I have to work at that real job again
I'm just off out to the shed to try the bifocals, maybe I can get bifocal welding glasses / lenses?

I know exactly what you mean. The number of times I mess around with settings trying to get the bloody welder to work only to notice 10 minutes later that I don't have my glasses on.

You can get non-prescription inserts that fit most modern helmets. You do have a decent modern helmet? I find I need both my normal glasses AND the insert. Also, get plenty of light on the job, it helps a lot.

Oh, ah, bifocals sometimes don't work real well, the right bits of the various lenses involved not lining up unless the helmet's clamped across your nose...

[Ocean1]

I tried multifocals, could not get used to them. Now I just take my -3 glasses off when welding. Without them I have 20/20 vision all the way up to 50 cm away.

Aye, the problem with needing glasses to weld is you're usually stuck with a focal range of maybe 300-600mm. Which is fine on the welding table, usually, but not much help if you're hanging off a ladder trying to finish the back of a pipe.

[Flettner]

I tig weld up all my gyro frames no problem but I haven't gas welded for some time. Perhaps part vison impaired and part just useless. I did buy a nice little Harris torch but buggered if I can get it to not backfire all the time. Harris not interested in fixing it.

[190mech]

I stack 2 pairs of reading glasses when I'm tig or gas welding,a 2.0 and a 3.5,heck now I can see the weld beads!!

[Frits Overmars]

bifocals sometimes don't work real well, the right bits of the various lenses involved not lining up unless the helmet's clamped across your nose...

The problem with needing glasses to weld is you're usually stuck with a focal range of maybe 300-600mm. Which is fine on the welding table, usually, but not much help if you're hanging off a ladder trying to finish the back of a pipe.

I've never considered hanging off a ladder to weld a pipe. Does it help?
My main problem with varifocals (i.e. bifocals with a heftier price tag) was laying back on the couch, watching TV through the lower, reading part of the lenses that blurred everything more than 1 meter away. Wearing the glasses upside down was not really an option either.

[Grumph]

I tig weld up all my gyro frames no problem but I haven't gas welded for some time. Perhaps part vison impaired and part just useless. I did buy a nice little Harris torch but buggered if I can get it to not backfire all the time. Harris not interested in fixing it.

Is that the pistol grip type ? I've heard of porous castings on those.

Reading glasses with clip on tinted lenses when gas welding for me. No fogging and i'm good up to 50cm.

[Flettner]

Is that the pistol grip type ? I've heard of porous castings on those.

Reading glasses with clip on tinted lenses when gas welding for me. No fogging and i'm good up to 50cm.

That's a good idea I must try it, thanks.

[Flettner]

I found the shoes wore first, I'd make wee stainless packers that clipped on. And bush the shafts. And hard face the cams... :

You got wonder if that's what the little recesses were put there for?

[Ocean1]

I've never considered hanging off a ladder to weld a pipe. Does it help?
My main problem with varifocals (i.e. bifocals with a heftier price tag) was laying back on the couch, watching TV through the lower, reading part of the lenses that blurred everything more than 1 meter away. Wearing the glasses upside down was not really an option either.

It does if the pipe in question is up in the roof trusses, although I must admit I don't do much positional welding now.

Which is probably a good thing because nowadays most such work requires compliance to standards associated with an orbital welding head, and while I can normally see well enough to set one up the price would make my eyes water something fierce.

[Ocean1]

You got wonder if that's what the little recesses were put there for?

As this is a thread to do with casting stuff I'd say it was more to do with what's keeping the OE steel liner in place while pouring. But it might also have been done to make a tight arsed Kiwi's life a little easier, we can't know for sure.

I like swarfie's idea too, and I thought of BMC's tapered cone adjuster idea for the pivot end, you'd just wind the cone in a turn or so when you ran out of brake.

[Flettner]

Ha ha, clean the googles!! makes a big difference. They have been sitting under the bench for some time and it seems a good lens clean makes a huge difference, dumbarse. I'll still try and track down some clip on lenses for my glasses as well.