An Alternate Method To Screw Cut Larger Pitches In The Centre Lathe .

well good day max ar welcome back to the shop I'm in Miss summer gear it's been hot over here we've been getting we've got a a week of um 40 41° temps in the shop here it's usually about 6° cooler than the ambient temperature outside so it's not too bad um any I just thought I'd slip this quick video in regarding threading now I'll show you an alternate method if you're banged up in a situation where you cannot angle your compound slide around it's just uh another method um it is a straight infeed cutting method using the cross slide but we also involve the compound slide so we'll switch swing it down and we'll show you what we're going to do so just for demonstration purposes I have a piece of hollow bar in in the lathe here and we've turned it down to 2 and 3/4 in so we're going to cut a 2 and 3/4 in 12 TPI thread on this piece of bar here or piece of hollow bar so that's what we're going to do and I'll show you the alternate method so generally you'd angle the compound around to 29 or 29 1/ 12° and all your in feeds are done on your compound going in so that puts most of the load and most of the cutting on the Leading Edge um of your screw cutting tool so the other alternate method is to leave the compound at 90 and you just go straight in feeds on your compound compound that works fine but once the the pitch or the threads per inch of your thread start to get larger and larger it puts a hell of a lot of load on the end of your tool and it's it's I wouldn't it's not a method I would recommend when you're starting to get into the larger size threads it it it leads to dramas through the excessive tool load um you get a lot of flex and vibration and and that sort of carry on so here's an alternate method so when I cut this thread let's say for every I in feed in 20 th I'll Advance my compound 10 TH or if I infeed in 10 th I'll Advance my compound in 5 th so I'm advancing the compound 50% of the in feed of the layer and then that will put the line share of the tool pressure on the Leading Edge of the tool instead of on the whole face of the tool and so the trailing Edge will just be doing a light clean up so then when you come to do your last few th finishing Cuts you can if you like plunge straight in on on the cross slide and not worry about the compound but that's just for your last finishing clean up Cuts so we'll do our first cut to be a 20 th deep straight plung in cut on the cross slide there on after we'll just do 10 th cuts on the cross slide and Advance our compound slide 5 sorry I bumped the camera there with my arm I'll have to move you okay we'll leave you there right so that's our first initial 20th th so all of our end feeds now will will be 10th hour on the compound for the next couple and I will reduce that back to five and and then we'll wind it down to a couple of th so our compound direction that way will be 50% of our ined now I might just get my phone over and we'll take a a closeup shot of the next cut and you'll get a clear picture of how the chip is coming off the tool [Music] sh you better I quick rub with the file [Music] [Music] [Music] [Music] [Music] nice let's get a close up of the thread one thing I will point out it is a a risky method to screw cut so it's not really for beginner machinists um for the this is the more experienced will will know this method and have it down pat if they do it all the time but it's not a method that I use frequently but it's just another one of those things you have up your sleeve to overcome uh problems so you know if if you get it wrong what the result will be you'll overcut the width of your thread and your root of your thread won't be deep enough I'll show you with a pitch gauge so if you messed up on your compound feeds you'll have you'll have a gap at the bottom at the root of the thread where the uh thread gauge sits in yeah so that's just another method um that we have up our sleeves to overcome any issues with screw cutting problems arise so we use different methods to get the same result probably find a lot of people that do hydraulic cylinders may use that method um quite a lot it saves all the mucking around adjusting your compound like from what I gather here in Australia and how I was brought up we normally leave our compound angled parallel with the bed um it's more I've seen the American style to to leave it angled around so whe that's so it remain set up for screw cutting or it's to give them extra clearance for the tail stock either or but um yeah so yeah just I thought I'd slip this one in so um and that is a Common Thread too 12 TPI 2 and 3/4 in common as anything but anyway cheers thanks for watching and uh probably see us in the next video

Channel: Max Grant ,The Swan Valley Machine Shop.

Views: 39,356

Keywords: tool post grinder, internal & external lapping, jig grinding attachment, lathe, machine shop, milling machine, tool & cutter grinding, machining videos, home machine shop, toolmaking, lathe maintenance, ID grinding

Id: CCDP6SFB2Io

Length: 13min 11sec (791 seconds)

Published: Sun Jan 14 2024