ER32 Collet Chuck for Proxxon PD 400

[Wongster]

The process of turning the nose is a long one. For the past couple of hours (with interruptions), I only managed to bring the diametre down from 100mm to 90mm. The target is 50mm for a length of about 25mm. Consulting the chart on the lathe, I'm supposed to set the belt to spin at 80 rpm and change it to 160 rpm when I'm down to 80mm diametre. I tested depth of cut at 0.1mm to 0.5mm. Not being comfortable going at 0.5mm, I reduced the depth to 0.4mm. I adjusted the spindle speed to 160 rpm and it seemed to be working fine.

I'm not sure if I'm getting this speed and depth thing right. A video was taken with my iPhone showing the cut with spindle at 160 rpm, depth of 0.4mm, and with autofeed at 0.07mm/rev. I was told that the steel block I bought is mild steel. Wonder if anyone can tell just from this video that I should adjust any of my settings (speed, depth of cut etc).





Regards,
Wong

[DaveH]

Hi Wong,

This type of turning (turning to a boss) is a bit of a pain for all of us in the home shop environment. It tends to be a slow process for all of us. After all we have to consider our machines.

Speed and feeds - your’s look good to me, and if your lathe is happy then it is right, and the finish looks good.
If you wish to try and speed up the process, increase the feed, leave the rotational speed the same. Your finish will not be as good but nearer the 50mm dia slow the feed down and do a couple of finishing passes.

Looking good

DaveH

[Wongster]

Dave,

I've 2 speed settings for the auto feed; 0.07mm/rev and 0.14mm/rev. At 160 rpm with 0.07mm/rev, I can hear some "grinding" sound during the cut. I hope that's normal.

If I keep all settings unchanged but increase the depth, will I have problem(s)?

How would you do this?

Regards,
Wong

[DaveH]

(05-01-2012, 08:40 AM)Wongster Wrote: Dave,

I've 2 speed settings for the auto feed; 0.07mm/rev and 0.14mm/rev. At 160 rpm with 0.07mm/rev, I can hear some "grinding" sound during the cut. I hope that's normal.

If I keep all settings unchanged but increase the depth, will I have problem(s)?

How would you do this?

Regards,
Wong

Hi Wong,
The noise is the "cutting" noise - sometimes some cutting fluid will help the cutting action.

"How would you I do it" - well my first consideration is for the well being of my lathe, I don't like to "force" it, I can't afford to break my lathe.

Increasing the depth of cut for the same speed and feed nearly always increase the "strain" on the lathe. I'm always gentle with the depth of cut.

Me - I nearly always increase the feed, the finish looks like a fine thread sometimes but I can do some finishing cuts.

It is going to be slow Wong, and a lot of swarf
You are doing fine, slow and careful is always the way

DaveH

[EdK]

I agree with Dave. You're getting nice long, curled swarf which usually means you've set the feed speed just about right. I wouldn't go any deeper than you are. I'm familiar with the grinding sound you mentioned and I usually get that when I'm cutting too deep for the conditions. Keep at it, you're doing fine.

Ed

[Wongster]

Thank you, gentlemen. I'll be patient. The turning of the boss may take a few sessions of my shop time, spanning over a few weeks - so be it.

Regards,
Wong

[Wongster]

May I know if I've angled the tool correctly?



Regards,
Wong

[DaveH]

Wong,
Yep, looks good,
A degree this way or that way will not make much difference (to us in the home shop)
Sometimes I just move my cutting edge a degree, gives it "fresh edge" or at least that what I think! No idea if it really helps, but it helps me


DaveH

[EdK]

Wong,

Nothing wrong with that angle. That's a fairly large radius on that insert. A smaller radius would be better for roughing and the large one for finishing cuts. That's certainly not cast in stone though.

Ed

[Wongster]

The reason why I asked is, I often see pics of roughing done with the tip of the tool angled away from the spindle end. Mine is pointing forwards towards the spindle. The HSS roughing tool in the box from Proxxon has the cutting edge slopping away. So I thought I got it wrong all these while.

Regards,
Wong