1st attempt on lathe

Those jaws are not reversible . They are solid jaws . Not sure what you are saying as far as the chuck not holding . Your spindle bore is the limiting factor for shaft work unless you're going to run a steady rest .
 
let me try to explain the chuck forgive me for not knowing all the correct terms

the center of the chuck has a hole lets say it is 1.25 inches. So stock less than 1.25 can be held in the center and tighten. But just for example it seems to me the next set of jaws(the ones in the middle) would have a minimum hold diameter of 1.5 inches. So how would I hold a 1.4 inch diameter piece.

thanks
 
I believe you are referring to the jaws in your pic ? They are jaws for chucking on the OD of larger parts and are regularly used with your tailstock for shaft work . They will hold short length pieces safely also but remember your L over D will limit you to the length you can safely machine without a steady or your tailstock . It's not good when you find out the hard way . :eek 2: If your diameter falls in between your jaws , use a split ring to suit your needs .
 
You should have either two sets of jaws or reversible one-piece or two-piece jaws. You may only have one set which will limit you.
As far as adjusting the compound angle, you can use the face of the chuck as a perpendicular reference point. Adjust the compound so your tool is parallel with the chuck face. That's one way. Use a square piece of material as a helper in between, then remove it.
Mark
 
First, congratulations on your first work piece. Regardless of how it turned out it is your first and that's cool! It will get better as you learn to use your lathe.

Your jaws may very well be reversible. Many scroll chucks (your 3 jaw chuck is called a scroll chuck) have reversible jaws. You have to unwind the jaws until they disengage from the scroll, flip them around and reengage them properly. We discussed how to do that here: https://www.hobby-machinist.com/threads/chuck-run-out.50125/. Skip down to the part in my post that discusses how to reinsert the jaws. As it stands now, your jaws are configured to allow you to grab parts that are larger than the center hole in the chuck but for your work piece the jaws will work better for you if they are reversed.

We cannot advise you on your turning tool without pictures of what you are working with. Maybe post some clear pics of the tool and we can comment and hopefully help you. It would also help to know what kind of steel that is and what your speed was when you turned it.

To get a parting tool perpendicular to the work, align the side of the tool with either the face of the work if it is faced square or align it with the face of the lathe chuck and then lock the tool post down.
 
Mr. Pete did a series of videos on grinding tool points. You may find them helpful. I know I did.

 
When you grind a cutoff tool, there is clearance (tapered sides from top to bottom, and the top of the tool will have some taper from the the front, contact point, to the back. This is why when you run the cross slide in, the cut will be perpendicular as long as the side of the cutoff tool isn't dragging in the slot. If you think of your tool bit for turning, the cutting edge isn't going to be parallel with your stock, otherwise it would drag the whole way. The movement of the carraige is what produces the parallel motion to the stock. The tool bit will be ground and positioned to give some clearance. I'll try to make a sketch.

20180219_152459-800x600.jpg

20180219_151751-800x600.jpg
 
The angles in my sketch are exagerated but this will give you an idea. Also, if you angle the face of the cutoff (parting) tool, the angle should be this way. Then you part will drop off cleanly

20180219_153349-800x600.jpg
 
First, Welcome to the Hobby-Machinist!

You have lots of great advice above.
I'll just add a couple things.

1) If you do remove the chuck jaws then mark them to make it easy to get them back into the same slot! The teeth that engage the "scroll" are at different offsets from the edge of the three jaws. Sometimes the jaws are stamped with number (1, 2, 3) and the chuck would have matching number stamped beside the slots. If not, then you could use the corner of a triangle file to put one, two, or three little notches on each jaw and slot. You could try a sharpie, but I find those marks go away too quick with handling.

2) For aligning the tool square to the axis of the lathe (and the work) I normally put the side of my tool-holder against the flat face of the chuck between two jaws. I have a quick-change tools post (QCTP) so the tool holders all have flat sides, making it easy. It looks like you have a rocker type tool post and holders, so it might be a little harder to get a flat surface to align.

3) For cutting speed, I use 80 surface feet per minute (sfpm) for a HSS tool cutting mild steel.
To convert that to RPM, you need to consider the diameter of the work piece.

RPM~=(sfpm*4)/dia
For your 1.25" diameter work piece, I'd get as close as I could to RPM=(80*4)/1.25=256 RPM.
So your 300 RPM is very close and should work.

There are many useful online calculators:
http://www.monstertool.com/monster_tool_calculators.html
http://www.americanmachinist.com/speedsfeeds-conversions-calculator
http://www.custompartnet.com/calculator/turning-speed-and-feed

4) For some great info on general lathe work see the free PDF version of SouthBend's How to Run a Lathe:
https://www.hobby-machinist.com/resources/sb-how-to-run-a-lathe-1966-27th-edition-56-pdf.2909/

Have fun and be safe!
-brino
 
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