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Steel castings?

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Cornish Jack16/11/2011 14:39:30
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G'day all.
No doubt rthis will seem somewhat odd, but how common are STEEL castings?
I'm in the middle of making a mess of a Sieg Hot Air Engine kit and machining the 'A' bracket supports. They looked like (the expected) alumimium castings when first seen but machining generated blue chips and some sparks!! Can't think of any particular advantage of steel in this area and it certainly makes life somewhat more challenging. Any thoughts as to why Sieg went down this route, anyone?
Rgds
Bill
JasonB16/11/2011 17:02:07
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Are you sure its not SG Iron as that machines more like steel. Reason for its use is lesss likely to crack thats why its used on traction engine front axles and crank shaftes for example.
 
J
Cornish Jack16/11/2011 17:11:52
1228 forum posts
172 photos
Thank you Jason.
No, not at all sure what it is. The external and internal surfaces were 'as rough as guts' and the first cuts were like getting under the skin of iron castings. However the brackets support the crankshaft which is made up from quite thin section brass strip webs and insubstantial pins in brass bearings - overkill and underkill??
Rgds
Bill
JasonB16/11/2011 17:22:55
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Ah just had a look at one and see what you mean
 
Looks like they have found a use for the dross off the top of the crucibles before they pour the lathe parts
 
J
Stub Mandrel16/11/2011 19:34:55
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I always assumed those bits were laser cut. Are you sure that's not teh case, the chilled edges of laser cut parts can be hard.
 
neil
David Colwill16/11/2011 21:08:13
782 forum posts
40 photos
If they are laser cut then I seem to remember John Stevenson explained a way to remove the surface with patio cleaner!
Terryd16/11/2011 21:26:28
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Posted by David Colwill on 16/11/2011 21:08:13:
If they are laser cut then I seem to remember John Stevenson explained a way to remove the surface with patio cleaner!

AKA hydrochloric acid (Muriatic for our North American Friends). Not so difficult to obtain.  Not really a secret as it is used in the steel industry as a pickle.

 
T

Edited By Terryd on 16/11/2011 21:27:10

Ian S C17/11/2011 00:55:43
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7468 forum posts
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Have not had a look at the motor yet, but I would scrap the steel work, and fabricate new bits from aluminium, or brass. Mind you thats just me, I build mine without using kits, or much in the way of other peoples design. Ian S C must have a look for the Sieg motor.
Cornish Jack17/11/2011 11:14:12
1228 forum posts
172 photos
Interesting comments and suggestions, thank you.
Neil - could be; only previous experience of laser cutting was a batch of Minnie wheel spokes and the finish on those was very smooth; these are much more like casting finish. Ian - yes, had considered that but persevered on the mill and now have reasonable surfaces (close enough for Government work!!) so will struggle on.
The main crank looks worryingly fiddly - built up from brass webs and steel shafts and (with no instructions) presumably press fits. Definitely a case for my 'Good Lord, that was lucky' tolerance machining

Edited By Cornish Jack on 17/11/2011 11:15:12

Ian S C18/11/2011 09:50:54
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Jack, I had a look on U tube and saw the HAE 03, looks good but I still think a pair of aluminium castings would be better on a kit like that.
The crank shaft should be easy, but if its like the Grizzly beam engine it might take a bit of lining up. That one has two bits for the main shaft, and one bit for the crank, where as the way to do it would be one piece for the main shaft which after assembly is cut between the cheeks, all lined up.
My latest motor, finished last night was built that way, and glued together. It has a crankshaft 3 mm dia. The stroke is 1/2" power cylinder is 3/8" bore, and the displacer is 1/2" dia, that cylinder is made from the steel casing of an AA Ni Cad battery. It passed my two tests, (1) turn the motor over by external power, and note the temperature drop. (2) Take the flywheel off, and start the motor, no torque, plenty of revs. Ian S C
Cornish Jack18/11/2011 11:19:01
1228 forum posts
172 photos
Thank you Ian.
Agree about the ali castings but have now (more or less) got them sorted Your crankshaft idea sounds better than the kit version - 'glued together'?? Loctite ?? or epoxy resin?? or?? 'cos I haven't used glue in engineering context. If I knew a bit more about these things, I suspect that I would be mightily impressed with your latest.
Rgds
Bill
Ian S C18/11/2011 11:54:04
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7468 forum posts
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Bill, I use Loxeal 8321, but a shaft lock Loctite would do just as well, The Loxeal is a high temperature glue, I use it for sticking a flange on displacer cylinders, and the cold ends in displacers, I also used it to stick the hot cap on the hot piston of my Ross Yoke ALPHA motor. Ian S C
Cornish Jack19/11/2011 11:00:40
1228 forum posts
172 photos
Thank you, Ian. I'll see what's available on line here and give it a whirl.
Rgds
Bill
Ian S C19/11/2011 12:13:23
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7468 forum posts
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I'll get a photo in an album soon, although it goes well, its not finished yet. Ian S C
Cornish Jack21/11/2011 10:54:07
1228 forum posts
172 photos
Another question, I'm afraid. Found the Loctite website with 13 different types available ... which one?? Application is to secure a 4mm steel shaft in 3mm brass crank webs. The variety on offer makes choosing the correct one tricky. Could anyone offer advice, please?
TIA
Rgds
Bill
Ian S C22/11/2011 10:15:16
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7468 forum posts
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Can't find my chart for Loctite, but if you use the highest strength you can find, and get one with a high temperature rating conbined with the strength, you (well I) can stick some of the hot bits together.
My little glued up crankshaft is holding up so far, its done about an hours running so far, 3 mm shaft, 3 mm boss on the steel crank cheeks. The crank pin is 3 mm into 1.5 mm , thats the weak point, so we'll just have to see what happens! Ian S C

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