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30th Aug 2015, 09:31 AM #1Golden Member
- Join Date
- Aug 2012
- Location
- Australia
- Posts
- 645
Safe rotational limits of 4E cast iron?
I have a 150mm disc ~24mm wide that I am intending to use on my bench grinder as a lap. The cast iron is 4E grade. Before switching the 2800rpm machine on I thought it best to see if anyone knows the safe rotational limit? I did some reading on car flywheels which are much larger and rotate much faster but they are likely a different grade of cast.
Any thoughts on the safe rotational limits of 4E?
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30th Aug 2015, 03:36 PM #2
I wouldn't worry about it, the tensile strength of 4e cast is likely to be better than that of grinding wheels. In any event, I imagine the guards for grinding wheels would be still there.
I've been using diamond lapping disks, and they work a treat on carbide. http://www.cutandslice.com.au/specials
I also got some from a cheaper Chinese source, but I've lost the URL, BobL might remember where the supplier, he was the one who found them.
Found it, http://www.thk.hk/online-cart.php?cid=36&sid=39 600 is good for shaping, 1200 and 3000 are good for polishing or touchup.
Ray
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30th Aug 2015, 04:57 PM #3Banned
- Join Date
- Jul 2011
- Location
- Melbourne Australia
- Posts
- 1,376
Ray.
Where did those magnetic backed laps come from? And have you tried them yet?
Also, how good an edge does that #3000 give you. I imagine its slow, but is it better?
Regards Phil.
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30th Aug 2015, 05:01 PM #4Pink 10EE owner
- Join Date
- Aug 2008
- Location
- near Rockhampton
- Posts
- 6,216
Engine flywheels are often cast iron, and they do many many rpms...
They are a bit cheaper here http://richontools.com/index.php?mai...ndex&cPath=1_9Gold, the colour of choice for the discerning person.
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30th Aug 2015, 05:20 PM #5
They came from the "cut and slice" mob, I have mostly been using the others without the magnetic backing, they hold just fine with the nut and washer against the backing disk.
No idea how the 3000 compares with the cast iron diamond lapping plate, maybe we can do a few experiments one of these days when I'm down that way.
Ray
PS Just for comparison, I think the 3000 grit works out to about 4-8 micron grit size, so you'd think it would be comparable to 5 micron paste.
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