I have fitted the fireplace I posted about earilier, all done!! I have a fire grate front (if thats what you call it!) but it is just too wide to fit into the opening of the fire so sits proud of the fire basket (?) can I grind the side down so it will fit?
can you grind cast? or am I just oissing againt the wind trying?
thanks
The beds and slideways of most high quality machine tools are made of cast iron and ground to high precision. Unless it's very poor quality stuff it should grind beautifully.
Certainly, either with carbide burrs in a Dremel or similar or with an angle grinder and ferrous grinding disk.
Yes, you can grind cast iron. But beware.
As a result of the casting method, cast iron has a surface that resists corrosion to an extent. If you grind it, you will remove that surface and therefore the corrosion resistance.
So make sure that you protect the ground surfaces against corrosion, just as you would for mild steel, for example.
Oissing against the wind must carry its own risks. ;-)
Yes, you can.
In fact its about the only sort of machining that works on it IIRC.
Cast iron used in brake discs and flywheels in grey cast iron, or crank shafts and wheel hubs in nodular cast iron can be machine turned & milled easily.
Don.
You don't, remember correctly that is.
crankshafts are seldom cast. IIRC they are nearly always forged from something rather different..steel!
I think we are running into semantics here: to me cast iron is the basic stuff that runs out of an ore processing furnace before its been blast furnaced!
Not how that part was actually made.
Well, provide examples.
Not of cast steel, but cast *iron*.
No they aren't!! The vast majority of standard automotive crankshafts are as you have already been told - cast iron. Only race engines and the occasional very high output road engine use forged or cast steel for crankshafts which although having a higher tensile strength is much more notch sensitive than iron and has a shorter fatigue life.
The vast majority of engine camshafts are also cast iron although in this case usually chill cast iron to give a high degree of hardness to the cam lobes. Engine blocks, cylinder heads, brake disks and flywheels are also commonly made from cast iron in various grades and all of these are readily machineable except for the hardened chill cast regions of a casting which must be ground to final shape.
Just putting IIRC after everything doesn't give you the right to blether on incorrectly about things you haven't actually forgotten because you clearly never knew anything about them in the first place.
Having worked for 5 years in an iron foundry, I can assure you that the vast majority of castings are machined prior to their further use. We used to make crakshafts for Vauxhall, as well as numerous other components such as camshafts, exhaust manifolds, and many other small parts for the motor industry. Alan
Bollocks.
Casting this sort of thing gives a more rigid result than forging - important with a crankshaft for engine refinement. It's also cheaper. Forging is only normally used where the maximum strength is needed - like when an existing design is modified or developed to produce more power than originally intended.
Unfortunately no, not by any measure. Cast iron has a lower modulus of elasticity (the amount it bends for a given load) than steel as well as lower ultimate tensile strength. A cast iron crank, of the same shape, is both more flexible and weaker than a steel one but as I said previously it is less notch sensitive so less likely to break from stress cracks and has a longer fatigue life which is important in high mileage engines like truck diesels.
In simple terms cast iron is used because it suffices for the job at less cost than steel. Even with very highly tuned engines putting out several times their stock power I've never seen a stock cast iron crank break. There's no reason to change it unless weight is of paramount importance in which case steel, being stronger, can use smaller lighter sections for a given loading. However, when weight is pared to the bone, as in a no holds barred race engine, then steel cranks can need to be changed regularly because their fatigue life can be quite short.
The other main reason steel is used for race engine cranks is because for small volume production it's easier to machine the crank from a solid billet of round forged steel bar than make expensive forging or casting tooling. Only when volumes reach production vehicle levels does such tooling cost per item drop to a manageable amount. You might then ask well why not machine small volume cranks from cast iron continuously cast bar? Mainly because given the same amount of machining from the solid bar there's not a sufficient material cost saving in using cast iron rather than forged steel bar to make it worth the bother when you are also going to get an end product that's weaker.
Sort of goes against what I was taught - although it could be if designing both for exactly the same load the cast one becomes in effect more rigid?
Crikey - broken crankshafts used to be quite common on thrashed engines - the B series BMC unit was famous for it. Early A series too. Of course with modern ignition/injection systems it's easy to limit the maximum revs to a safe limit.
Quite possibly yes if you have to make the sections very much bigger to allow for the lower tensile strength. In fact that's why you generally only see cast iron things in bloody great lumps because it's basically weak and brittle, especially in thin sections. However in bloody great lumps you still ain't going to break it and it's cheap.
I'm talking 'proper' engines :) Ya know, like anything designed after the Ark?
The A series, and the early B series, only had three main bearings on the crank which is why they bent like bananas under high rpm loadings and broke so easily. Anything more modern will have five mains and be very hard to break.
I accept that modern cranks are made of malleable or SG Iron - but I was fascinated to see a RR Merlin crankshaft forging die and forging at a museum in Sheffield, They were forged with the cranks in one plane - then a twist was applied to each web to give the angular relationship - then machined. Amazing.
Photo of RR Merlin forged and twisted crank - with forging die - all in one plane
In message , "Dave Plowman (News)" writes
Managed that once
I also broke a camshaft on my SD1 in three parts thrashing it down the autobahn once ... so watch it
On the V-8? Pretty rare I'd say. The distributor drive usually gives up first. Which, of course, also drives the oil pump. I'd be less surprised if it was the 6 cylinder.
Snapped a camshaft on a corsa once. Not sure if the belt went first.
Had to tow it to Calais and onto the ferry home..
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