New To Machining With A Question

[boostin53]

I have the manual. I dont know why i didnt just look in the back and get the part number for the chuck key. Thank yoi for the help guys!

 

[kwoodhands]

Hi y'all! This will be a sort of long first post, so please bare with me as I'm totally new to all of this. Been browsing this site for a few weeks now in preperation to begin a new hobby/addiction (machining). I decided to start small with a Jet BD-920N lathe that I got for a very good price. The lathe came with a bunch of extra stuff and including some basic tooling. It was too good to pass up considering it was basically free.

I have been practicing facing and reducing on bolts and some scrap 1/2" steel bar stock of unknown to me metal from work. Today I decided to face and center drill a 12" length. I started by only hanging about an inch and a half out of the chuck, faced and center drilled. I then put in my live center on the tailstock and extended the work piece out.

I began turning down the steel to my desired diameter of .415". While confirming measurments during the turning process, I noticed some variations on the measurments. The front half measures in at .416" while the back half measures in at .427". I then thought maybe I didnt turn in my tailstock enough to support my work, causing some slop. But it was good and tight. So to wrap this essay of a post up, what can I do to eliminate this and get the same diameter on the entire length I'm turning?

Center drill both ends and turn between centers. Turn to dimension about 3" from the TS end. Turn to about .002 full til you get about halfway.Reverse the part,turn to dimension .The 3" turned to dimension is to clear the lathe dog after reversing the part.I leave the part .002 full so the last pass at slow carriage feed leaves a smooth surface.
As mentioned a rest set up in the middle will help with deflection.If the live center is turning ,then the TS is set okay.
It would be rare if the TS is centered for height and laterally correctly.Turning between centers eliminates most of the problem.With our lathes .415/.420 would be considered good.

mike

 

[don00298]

Hi everyone, glad to be a member now. I purchased a 13" south bend in December, this old lathe was built in the mid to late 40's I think, and is in fare condition for its age. I also have a Maxmill (1970) which is a Japanese version of a Bridgeport vertical mill that I've been using since the early 80's, that being said I have some knowledge of machining metal. This is my first lathe and at the same time the first lathe I have ever touched or used. My question is when I try to face the end of my work the apron tends to move side to side (chuck to tail stock) therefore the cut is not true, is there a way to lock the apron (handle) in order to prevent this? Is there an adjustment to increase the horizontal drag or is this a problem with the lathe itself? Any suggestion much appreciated.

 

[T Bredehoft]

Somewhere on the saddle (that part that slides left and right with the tool on it) is (generally on the right side) a generally square end of a bold. This should lock down the saddle, to keep it from moving left and right. There are screws across the back (with nuts on them) that adjust what are called "gibs" (pronounced like the guy on NCIS) these are to adjust the friction between the saddle and the 'ways', the rails the saddle slides on. Be aware than any old lathe may have wear under the gibs where the lathe is used most, near the chuck, and if the gibs are adjusted snug at that point they may be tight as you move the saddle to the right.

End of Saddle 101

 

[TC0853]

First I would set up a dial indicator and check for runout in your 3jaw Chuck. That would account for your work getting small the closer you get to the headstock If you suspect your tailstock is out, go to this YouTube link
https://m.youtube.com/index?&desktop_uri=/#/watch?v=utZVv7QvRt8 . If that won't open it up just do a search for lathe tailstock alignment tool by Ray Caniglia. He put that segment up at least a couple years ago, it's a nice little easy tool to make, and you'll need a starrett 196 back plunger dial indicator, they're on eBay all the time. That way, instead of checking the tailstock by eye you can dial it in to .001" or less. IMHO! Also, like someone mentioned earlier the more of your work in the Chuck, the truer it will be. Good luck!

 

[Wreck™Wreck]

First I would set up a dial indicator and check for runout in your 3jaw Chuck. That would account for your work getting small the closer you get to the headstock

Actually it doesn't account for this, the spindle will describe a circle on the cut surface regardless of how much run out a chuck, center or collet has, it will not cause a taper condition. The turned portion of the material will not be concentric with the portion held in the jaws/collet however.

 

[stupoty]

I wanted to get a nice slip fit for a shaft to run in bearings with a 5mm id , it was only about 1.5 inches long though, i ended up doing it unsuported and correcting areas that flexed most manualy using a shear tool then a file then blended them with abrasive cloth paper (i have some nice 1" wide stuff on a roll) i managed to get it withing less than a couple of tenthes all the way along. Bigger lengthes would take longer it wasn't a quick process to be fair.

Stuart