Sunday, January 8, 2012

PD400 - Tailstock Locking Lever - Part 2

I continued my work tonight on turning down the steel stock to the size of the bolt head.  The stock was cleaned up first and re-chucked for sufficient length to turn down to 13mm.  No support was used at the tailstock end.  Spindle speed was set at 660 rpm with power feed at 0.07mm/rev.  I started with carbide insert tool before switching over to HSS as I was told that the speed table on the gear box is for HSS tools.

After I switched over to HSS from carbide, I observed that the surface finish was rather bad.  But as the diameter gets smaller, finishes improved quite a bit (under 18mm diameter).

Here are the pics:

The stock was flipped over to clean up the rusty surface. The rounded end was faced off first. This was a test piece after I converted my Sherline4410 lathe to CNC.  HSS tool being used.
Facing operation completed. 0.3mm per pass was used.
The cylinder face was turned from 22mm to 20mm, matching the turned portion. It was perfect! I got it to exactly 20mm (or less than 0.01mm, the resolution of my Mitutoyo Vernier Caliper).
Deciding how much to put in the chuck jaw.
Lathe in operation. The 0.02mm error is pretty consistent throughout the turning operation.  I'm taking 0.2mm per pass to reduce the diameter (0.4mm off the diameter per pass).
13mm diameter reached.  The last 1mm was done with 0.1mm depth per pass. This dimension is not critical but done for the fun of it.

In my next session, I'll be turning down one end to the major diameter of an M8 bolt (30mm length) to prepare for threading.  This will be my first time making threads on the PD400.  I'll be reading and re-reading the section in the manual on changing of gears and the recommended procedure of thread cutting.  I'll also be getting some 15mm round steel stock to stand by in case I screw this piece up.  All steel rods in my box are 25mm in diameter.  I don't want to go through another session just turning them down to the required dimensions.  Shop time is rather precious to me.  I tried various depth to see how deep I can go but at 0.3mm, I "sense" the extra effort in the machine peeling off the steel.  Maybe it is just in my mind - I'm too scared to go deeper.  Maybe I should really go at 0.5mm to remove 1mm off the diameter at every pass.  Hope someone can tell me that it is ok to go at that kind of depth with the PD400.

That's all I did in about 2 hours.  Time to hit the bed.  Hope to have some time tomorrow for more fun in the shop.

God blesses you all!!!

No comments: