Low personal B.M.E.P.
Now if you could operate the water valve by servo and link that in to a tacho function you'd have a quick way of getting load readings at stepped RPM....Originally Posted by Flettner
But i've been spoilt using a Dynopak setup which does that for you. Very nice too.
Forum whore
Yes, on the mark two setup, for now I just have to get results. G clamps and zippy ties everywhere. Exhausts held in place with ladders and a plank (and springs).
Forum whore
My first brake was not unlike yours; it was a British Heenan & Froude water brake. But it was never designed to cope with racing two-strokes. When the engine came on the pipe, the revs immediately shot sky-high because once in the power band the engine's torque curve was way steeper than the brake's torque curve.
Doubling the brake's rpm and tripling the water pressure finally reshaped its torque curve into something more or less usable. But the high water pressure made the hoses want to straighten which influenced the force actuated by the brake on the scales. Besides, controlling the water flow was by a hand wheel and laying a hand on it already influenced the scales. If you want to measure anything like accurately, you'll need a fast servo control on the water flow.
Forum whore
MikeT1 , how many are you? I read in the motor times about a guy in the Waikato who makes steam bikes? Tell me there is not two of you?
L-Plate Rider
Hi Flettner, don't think it was me in the paper. So there must be more than one steam bike nut out there. How is the dyno working out ? been waiting for an update. Have modified mine to gear up the drive to the alternator and increase the load on the engine, need to recalibrate the rpm and load cells to suit.
Forum whore
The out door nature of my dyno is not so good in winter, waiting for a few fine days.
Hardcore Biker
Yesterday my friend Jeff had a foundry party at his house. Some photos from it are in this folder on my website:
http://www.eurospares.com/graphics/metalwork/foundry/
Jeff and I have been collaborating on accumulating foundry supplies for casting aluminum. Jeff has made a high-performance propane furnace while I've picked up a nice electric kiln. But until yesterday we hadn't tried melting/pouring any metal.
Jeff organizes a dirt bike ride in the California Sierras each year, and one of his friends on the ride designed and had 3D printed a medallion to give to everyone. The printed part was used as the pattern. I think this was a laser/resin print, definitely not a filament deposition job (and Chris said the model cost about $160 to have done, and that was with a hollow back to reduce the amount of time and material needed to print). The medallion surface and detail looks very nice. The raised sections are .75mm tall. That design in the middle is the route for the ride. Before molding the pattern was filled with Bondo to eliminate flex.
Since there was only one pattern and about 20 copies were needed we knocked together a number of small flasks. We poured 3 or 4 times.
Since no great mechanical properties were needed (and we didn't know if things would work) the material was scrap - lots of pistons, aluminum connecting rods, small chunks from the machinery scrap bucket. We have ingots of A365 alloy for when we try casting some actual motorcycle parts.
We tried both commercial green sand and Petrobond and decided that we preferred the Petrobond.
You can see in Medallion3.jpg that some of the medallions are not so nice in the middle. We think that was due to the sprue coming straight into the pattern and slightly damaging the mold. But we didn't make the flasks large enough to offset the sprue and use a gate so we were kind of stuck.
I had bought a hot suit, spats and foundry gloves, but the process was much less dramatic than expected (I guess I'd been looking at photos of steel foundries with sparks belching out of blast furnaces) so they didn't get used. But I think I'll wear them anyway when I try melting with my electric furnace just in case Mr. Murphy pays a visit.
All in all everyone was pretty chuffed with how things came out. Everyone got to try their hand at making a mold. Jeff did the lifting/pouring and I skimmed dross for him. Even the "less good" medallions will clean up well enough so that everyone gets a souvenir made from motorcycle parts.
cheers,
Michael
Forum whore
That's Great ... grate party and interesting thing to do.
Muddler/Dabbler.
Sounds like a great time was had by all!
I have also found that it's not such a big deal and the dire warnings may put a lot of people off doing it.
No need to go overboard with safety gear,(talking aluminium here) but it's a good idea to always be prepared for the worst case scenario.
I think commonsense and having everything on hand, is probably the most important part of the safety requirements!
L-Plate Rider
It pays to be carefull, as two of my friends and myself can testify, thankfully I was wearing a face shield and the others were standing back enough to not recieve too much splatter. I had finished the pour and was pouring the excess into ingot molds which appeared dry - there was an almighty bang and molten ally everywhere, my faceshield carries the scars to this day thankfully not my face.
Muddler/Dabbler.
I think Flettner had a very similar experience a few years ago - he can explain.
I had a bad enough experience with wax recently (which can also cause severe burns) and I also had skin grafts on my right leg from a mishap with meths many years ago.
However, (as I see it), going overboard with safety gear can sometimes hamper movement etc. and doesn't overcome bad planning of your layout and not knowing where everything you need is located before the operation.
Yes I firmly do believe in a face shield of some sort - even a welding helmet! and leather gloves and boots. Maybe cotton overalls are ok. - no synthetics! and as you have just pointed out no dampness where the melt is being poured.
Forum whore
Yes, face mask, leather jacket, gloves and special casting shorts
Yes we did have an "incident" a few yeas ago, dumb and dumber.
Muddler/Dabbler.
Yes special casting shorts
I've found fireproof black singlets to be less restricting and cooler in the summer than leather jackets! - leather gumboots?
Hardcore Biker
I've got a welding jacket that is made of treated cloth. It seems to work fine resisting sparks or the occasional "pop" of molten metal when welding, but I don't know how it would hold up against a significant splash.
I'm ATGATT (all the gear all the time) when I ride, so since I've got the foundry gear on hand I've no problems with making use of it.
After watching the videos on YouTube "foundry shorts" has become a standard comic term.
We're talking about getting together next Sunday to see how effective my electric kiln is, and maybe try some more medallions with the sprues moved off to the side.
cheers,
Michael
Highway Biker
Casting is one of those things, that if your method is not correct, no amount of safety gear is going to save you. I remember seeing a guy using HF acid, I said do you need gloves, he replied, if you need gloves, you are splashing the acid about. If your procedures make it so you can't splash the acid, then you don't need the gloves.
I remember casting parts for my steam engine at high school, you would not get away with how I did it then, but I made sure the cast box was heated, and made sure the tray for the left over was heated and dry. Never had any incidents what so ever, I was in summer school uniform, I did have however the full face visor on. When doing the pour, one end was attached to the wall, and I only needed to pick up and rotate in an arc to the box and the left over tray.
Neil
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