Wanted cast iron back plate

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gi_984

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Have a chuck project that requires me to make a new backplate. Making a fixture to hold an old 3 jaw chuck to do repetitive round stock work at the bench.
Rather than buying a new blank or a semi-finished one; hoping someone has a damaged one or from a failed machining attempt.
Needs to be between 6-8 inch diameter. Cast iron only. Please message.
 
gi_984 said:
Have a chuck project that requires me to make a new backplate. Making a fixture to hold an old 3 jaw chuck to do repetitive round stock work at the bench.
Rather than buying a new blank or a semi-finished one; hoping someone has a damaged one or from a failed machining attempt.
Needs to be between 6-8 inch diameter. Cast iron only. Please message.
Click to expand...
Look around for a treadmill motor flywheel or a cast iron weight to make one from.
 
If it matters to your project, you should specify type of mount (i.e., 1-1/2"-8 Threaded, L-00, etc._).
 
Funny that mentioned this before but I have an old cast iron manhole cover sitting on a job that I hate to throw away. That would be a good source..
 
"Look around for a treadmill motor flywheel or a cast iron weight" Already checked the local repair shop for flywheels. Owner knows what I'm looking for and is supposed to let me know if one comes up. Having done a bit of weight lifting I'm familiar with the cast iron plates for bench press, hip sleds, etc. The thicker 35 pound and higher plates would be thick enough but way too large to turn down with either of my lathes. Not to mention the time expended.

"you should specify type of mount" Not applicable to my purpose. A raw casting or a semi-finished one is the easiest and most likely to be found. Instead of ordering one was hoping there was a failed attempt that I could repurpose.

Cast iron only? Because most of the inexpensive semi-finished and raw backplates I've seen are cast iron.
I have chucks with factory steel backplates. And I've made a new steel back plate for a Hardinge lathe. Would rather use CI for this project.
 
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Not to cause thread drift but having never machined a barbell weight I'm curius about the quality of the castings? Gas bubbles, blow holes, hidden defects, etc. I have machined a couple of cast iron sash weights to make some bushings and the castings were mostly OK but the safety issues involved make the failure of a bushing supporting a slow spinning shaft a little different than the failure of a flywheel disk at high RPM.

Too bad you can't find a cut off end of a malleable iron shaft. That is used a lot for hydraulic pistons.
 
Different brands of barbell weights are shaped ( thickness ) for the same size weight . I made a backplate for an 8" chuck , it was my first time trying something that big on my little lathe , it beat the crap out of it because of how uneven the surface was . Maybe on a larger lathe it wouldn't have been as much of an issue ,also it's very hard on tools
 
I have a Shars, 6" I paid about $70 more for the chuck WITH the backplate...just to find out it was wrong and ordered a blank from Grizzly. I don't think it's worth more than $35, but shipping is probably the killer...
 
Want to keep crossing off the to do list. So just ordered a new rough casting. Thanks for the replies.
 
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