how does that work without ruining the chuck stuck against it doing it on the lathe u would do it on a faceplate screwed to a sacrificial piece of woodRough out the shape with snips or a grinder then turn it size on a lathe with a magnetic chuck...
I need to make a 3" (75mm) disc from 1mm sheet steel - what would be the best way? - can i use a fly cutter (carefully), cut a square and grind it off to size or pay someone or can I buy disc blanks?
TIA
Mike
what have u got a watchmakers lathe3" disc, use smaller than 3" chuck...
Irrelevant for the job at hand but FWIW if you want/need to use a lathe to make accurate sheet metal circles/holes/annular rings then can stick the blank to the faceplate (or the chuck with the jaws removed, or to a chunk of bar held in the chuck) with some double sided tape and use a live centre in the tail stock to apply pressure. If the centre of the disc needs to be free of marks or holes then use a bit of scrap between the sheet and the live centre
As long as your name isn't johnny 5 thumbs the tape is more than thick enough to avoid cutting into the faceplate/chuck. It'll also hold everything in place* until the cut is completed (peeling the part off without damaging it is usually the longest part of the job) so you don't get results similar to what happens with holesaws on sheet metal... the huuuge burr typically left on the slug, usually irrelevant but not if you want the slug instead of the hole
Somewhere in the forums link section is a bunch of MIT machine shop instructional vids that demonstrate the double sided tape trick on both lathes and milling machines
* If the OD of the blank isn't supported it can vibrate/chatter like mad if there's more than a little overhang
if u have a lathe u will have a faceplate . why mess about with tape taking chuck jaws out and using a tailstock center when u just use the wooden sacrificial disk and screw your plate on and then part it off . no chance of it coming of if u get a dig in and its fastIrrelevant for the job at hand but FWIW if you want/need to use a lathe to make accurate sheet metal circles/holes/annular rings then can stick the blank to the faceplate (or the chuck with the jaws removed, or to a chunk of bar held in the chuck) with some double sided tape and use a live centre in the tail stock to apply pressure. If the centre of the disc needs to be free of marks or holes then use a bit of scrap between the sheet and the live centre
As long as your name isn't johnny 5 thumbs the tape is more than thick enough to avoid cutting into the faceplate/chuck. It'll also hold everything in place* until the cut is completed (peeling the part off without damaging it is usually the longest part of the job) so you don't get results similar to what happens with holesaws on sheet metal... the huuuge burr typically left on the slug, usually irrelevant but not if you want the slug instead of the hole
Somewhere in the forums link section is a bunch of MIT machine shop instructional vids that demonstrate the double sided tape trick on both lathes and milling machines
* If the OD of the blank isn't supported it can vibrate/chatter like mad if there's more than a little overhang
bothHole saw or snips an a fettle up
u should know by the forum has to overcomplicate things then make a plan to un complicate itYou're making a big deal of this! Just cut it out with snips and weld it on. There's no need for any precision here!
I have fly cutters, tank cutters, hole saws and a lathe, but for a suspension turret top all I'd need is the snips! It has taken longer to discuss it than it would to do the job!
i rest my case soz it had to be saidYou could always turn a die set up and press it out.