Cutting Low Tpi Threads

i hadn't considered using iron weights for turning material...:idea:
 
Can I ask why weights would need an internal thread on them?

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Nicely Done!! If you love your lathe you might want to consider covering your ways and using a vacuum while turning cast iron. Cast iron dust is about the fastest way to wear out a lathe that I can think of. If it gets into your gearboxes or carriage it will cause premature wear. Even a spanking new lathe with fresh wipers will let cast iron grit into delicate areas.

cheers
michael
 
atunguyd said:
Can I ask why weights would need an internal thread on them?

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It started as an experiment - I needed to learn how to cut internal threads on big flat plates before reaming out and rethreading a couple of 11tpi faceplates to fit my 8tpi lathe nose. Wanted to sort out the logistics of the cutting sequence and workholding before possibly making a mess of a Myford face plate whilst converting it to 8 tpi.


It seems to be finishing ok, which is a bonus, so now I will finish then nicely and see if I can slot them on the mill and do something constructive with them ie sacrificial face plates, table for pillar tool ?, table for something else, cut in half and use for a sharpening jig trunnion ? Base for a small tool/jig/fixture of some sort ?

Maybe I could trepan the thick rims off the edges and use them as wheels or cogs or pulleys on something ? A lot of metal is sacrificed off the rim to get the entire wheel flat

Would like to see if I can get a better finish on Mill carbide facecutter vs lathe HSS toolbit - am a mill newbie just bought it a few weeks ago.

I got some other weights a few days ago for $2.

Some people have reported that weights can be full of nasty uncuttable rubbish metal but it looks like I got lucky on this particular one.

I made a big effort to clean up as well as I could after a session due to the reported risks of nasty abarasive materials in the skin and also in the general dust - I am aware that some people have used dust extractors when machining cast iron.

Bill
 
Cast Iron can be dirty and gritty. Try to protect the ways either remove any oil and grease or use covers. If I read your post correctly you are cutting internal threads. The last time I cut threads with a boring bar I turned the bar over so it cuts on the back side of the hole. Doing so lets you see what is going on.

A quick tip if you divide 1 inch by number of threads will give you how far the threading tool will travel in one revolution. Ex: 1.000"/ 20 tpi = 0.050 per rev.

The Best with your project,
 
Nice job. When you mentioned low TPI threads I thought of ACME threads. Nothing really different except the tool.
 
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