Peck turning on the lathe (like peck drilling)

[hobby]

Hi,

I really like my HF. micromilldrill, I upgraded it with a longer X axis table, as well as extended Y axis base, so this machine is really good for me to use in my hobbies.

However it is poorly designed in one aspect, and that is, the shift gearing shaft, goes up part way through a bushing into the top housing, so as to keep this shaft vertical, however this bushing is poorly designed, as well as the material used is poor quality, after a while the bushing wears down and the shaft becomes wobbly.

So I replaced the bushing and made one out of tool steel, but that caused the shaft end to wear down, so again wobbly gear shaft, that's why I decided its time to upgrade this machine to a belt pulley system.

However since this machine is no longer sold by HF, then LMS, stopped selling the pulley kit for it, so I'm venturing out into new territory in my home shop machining experiance, and did some googling internet reasearch to learn about designing and building pulleys, and I have made a Vee- cutter for the LMS. supplied belt, (I'm using the commoin belt theat LMS. sells for the mini mill),
and made my first pulley that will attach to the spindle. The belt fits very nicely around this pulley,
now I'm making the second pulley, to attach to the motor, but because my milldrill is taken apart, I have no way to flatten my saw cuts, but on the lathe alone.

So after sawing a piece of 3" dia. aluminum stock to rough length, I made a quick mandrel to screw onto the workpiece, which leaves a very inacurate setup, due to the unlevelness of the end the mandrel is screwed to, so I end up with about 1/8" total runout, at the very end of the workpiece.

I was trying to take very small cuts at a time, but had tremendous chatter no matter what I did, than I stumbled onto this technique, I started to peck the workpiece using the crossslide to reduce any heavy chattering, and it worked so well, that I was able to knock down the 1/8" runout in no time with no serios vibrations on the machine.

Here is a video, of this technique, I plunge in and out (like peck drilling), only this is done on the lathe on the crossslide, while keeping the carriage moving along the length of the cut, it went so smooth, I was able to take deep cuts with good slicing of the chips, rather than the cutter bouncing and making dust and noisey vibration.

Here is the video.
At the end, I show the one pulley I have done so far.

"http://www.youtube.com/embed/khxARts5wXQ?rel=0"

I'm making a 4 speed pulley system, so as to not have to rely on controle boards all the time, if the controle board goes out, I can still vary the speed with the motor running full throttle, with this 4 step pulley design.

 

[hobby]

Hi aermotor8,
Thankyou for the suggestions:

I tried to slow the RPM's down and take very light passes, but I was still getting a lot of chatter, but when I raised the RPM's I was getting less chatter, but still a lot of vibration, on the cutter, by taking slow passes, so when I tried to take faster passes, It made it worse, the tool bit I was using is a HSS 1/8" already ground, since I'm not well versed in tool bit geometry, a lot of the vibration maybe as you said, a dull tool, or the wrong tool bit to use in that application.

I would like to use the tailstock center, for more support, but with my mini lathe, trying to turn a 3" dia. round bar, makes me have to turn the compound slide, where the handwheel is facing in towards the bed. making it impossible for the tailstock to reach that far over the compound slide, to make any contact with the workpiece.

I'll keep posted, on this project as it unfolds, and I'll put it in the "machine modifications" category.

Thanks again for your helpful suggestions...

 

[kvom]

That's what is known as an "interrupted cut", and your technique is normal for that situation. Obviously the more rigid/powerful the lathe, the deeper you can cut. I wouldn't try steel like that on your lathe, but for aluminum it looks as if it works just fine. The same technique applies for both facing and turning.

For making a pulley, you don't need a v-shaped tool. Use a parting tool to go in the center to the groove depth, and then form the sides using the compound.

 

[Brian Thomas]

no you tube link any more?

 

[hobby]

Hi Brian,

I was messing around with my computer, and experimenting changing my you tube settings and stuff, and got things messed up so I just closed that account, and I'll reopen again on youtube when I get ready to post new videos.