First tools for the AA109 lathe

[jaredbeck]

With high hopes for actually making something useful, I've gotten my first few tools installed on my AA109. When I got this lathe last month (http://www.hobby-machinist.com/threads/my-first-lathe-dont-laugh.61605/) it didn't come with much.

I managed to get a 3" chuck mounted on the 1/2"-24 spindle, and I got a 1/2" drill chuck on a MT0/J33 arbor. They look comically large on this delicate little lathe.



Facing operations close to the chuck seem to go well. Drilling is .. possible (more on that below).

For the chuck, I found a backplate with the right bolt pattern, but I had to turn down the "locater" step on the front of it. Without a way to slow down the motor much, this proved impossible with HSS tools, so I had to buy a set of brazed carbide tools. It came with C6 and C2 grade tools. I used the C2 and it managed to cut the cast iron backplate, but I'm still not clear on the difference. C6 is slightly softer and is meant for steel?

I can get 0.005" runout on the chuck. There isn't much rigidity in any part of this system. Just leaning on the workbench moves the spindle a few thousandths. When it's actually under power, the runout is probably much worse.

The runout on the drill chuck is really terrible. As I turn the tailstock spindle, the tip of the drill (pictured above) will inscribe a 1/16" diameter circle! There's slop in the tailstock itself, and I'm not sure the arbor is a great fit (I read something about these lathes not quite matching a MT0 taper). But, probably I just don't know how to align these parts? I hope it's me and not the tool.

When the drill bit gets about 3/4" deep into a cut it starts to get resistance. If I continue it feels unsafe, like the motor wants to spin the tailstock backwards against me. Maybe the drill will have less runout if I engage more of the tailstock spindle threads? The full travel of the tailstock is about 1.5". I'm not sure what to do. Your help is much appreciated!

 

[Ulma Doctor]

Hi Jared,
congrats on the new tooling!

C6 is for steels
C2 is for Stainless Steels, cast iron, non ferrous metals

you can use a sharpie and color the male part of your drill chuck taper and insert it loosely into the tailstock.
give the drill chuck a turn in the tailstock bore and observe the pattern etched on the taper.
where the ink has been rubbed off, that will show you the contact pattern of the interface of the 2 tapers.

drill chucks are not inherently accurate devices , but some of the high $$$ chucks are the exception.
it not uncommon to have greater than 20 thousandths runout on a run of the mill drill chuck.
don't let that fact get you down, because you have a lathe and can still bore a straight and accurate hole.
you'll just use a smaller drill to remove the bulk of material of an internal bore and then come back in with a boring bar and complete the operation to your satisfaction.

just like most things on a lathe, you want the shortest stick out of any member as possible, for the greatest rigidity.
that goes for materials held in the chuck, tooling stick out length, & tailstock quill extension

i hope the information is useful

 

[brino]

Hi Jared,

It's been a long while since I saw that model up close. Does it have a tailstock offset to allow turning tapers?

If so, you should check that the alignment between the headstock and tailstock is adjusted as best as you can get. Look for a locking screw and adjusting dovetail that would make the tailstock move back and forth 90 degrees to the lathe axis.

There are many ways to measure it at varying precision and price points:
-using two centres, put one in the headstock taper and one in the tailstock taper and align by eye,
-dial test indicator held in the headstock chuck measuring against a precision rod held in the tailstock chuck (or visa-versa), and turning the machine by hand,
-coaxial indicator (can be expensive)

-brino

 

[dlane]

Jared, sounds like a tailstock alignment is needed, should be able to search for that procedure here.
That looks like a thick back plate , I've heard if you cut the back plate register .008 undersize you can
Knock the runout out then tighten the mounting screws/bolts , someone would know more than I.

 

[T Bredehoft]

As I turn the tailstock spindle, the tip of the drill (pictured above) will inscribe a 1/16" diameter circle!

This sounds as if the tailstock spindle is revolving. it should be keyed so it won't turn.