Tumbler questions

[350xfire]

Guys, I was wondering if a vibratory tumbler would be a good device to get aluminum parts REALLY smooth and even after machining in preparation for some polishigng with white rouge?
If so, what media or what steps should be taken to achieve a nice smooth finish. My lathe leaves quite a few lines on the work. They are nice and even lines, but for some stuff I would like a smooth finish.

Thanks

 

[cmacclel]

Guys, I was wondering if a vibratory tumbler would be a good device to get aluminum parts REALLY smooth and even after machining in preparation for some polishigng with white rouge?
If so, what media or what steps should be taken to achieve a nice smooth finish. My lathe leaves quite a few lines on the work. They are nice and even lines, but for some stuff I would like a smooth finish.

Thanks

If your lathe is leaving lines then you need to adjust / change your setup. Try using a larger radius tool, slower feeds, ETC.

Mac

 

[350xfire]

If your lathe is leaving lines then you need to adjust / change your setup. Try using a larger radius tool, slower feeds, ETC.

Mac

Thanks Mac, I am running the slowest feed (0.04"/rev). Is the logical move to use a larger radius tool? I am using some of those cheap 5/8" cutting tools that come 5 in a wooden box. I have tried other tools, but all leave the same pattern.

 

[gadget_lover]

.04 is still pretty coarse. That's only around 25 tpi, right? (my head's too fuzzy for math today). I have gear combinations that will bring my feed down to .0039 ( 1/256 of an inch per rev).

You could always crank it by hand. I've done that an gotten a nice finish on a 3 inch long piece of aluminum.

IIRC, the idea is to use a broader radius tip than the movement per revolution. You can regrind the radius on the cheap 5/8 tool that is HSS or brazed carbide. You can step up to a different insert if using indexible.

Dan

 

[350xfire]

Oops, sorry... I provided bad info... My minimum feed rate is 0.04mm per rev. I tried doing combinations of feeds and my speed is set to 1500 RPM (fastest) and got nothing but wider grooves as the feed was increased, pretty much expected.

Can anyone tell me what tool radius I would need to achieve smoothness at that feed rate? Oh, and my tool is indexable!
Thanks again...

 

[gadget_lover]

A radius of 1/16 inch will do the trick.

Wider grooves as the speed was increased? That sounds like the feed is not per rev but is instead per some unit of time. If it is per rev, then the grooves will be the same width no matter what the speed.

Dan

 

[cmacclel]

The tools I use for finishing have a 0.015 radius. My boring bars have a 0.007 radius. I usually feed .003 per revolution on the finish pass.

Mac

 

[350xfire]

A radius of 1/16 inch will do the trick.

Wider grooves as the speed was increased? That sounds like the feed is not per rev but is instead per some unit of time. If it is per rev, then the grooves will be the same width no matter what the speed.

Dan

No the grooves widened as the feedrate was increased... With changing speeds for any given feedrate, the grooves remain the same.

I'll try a bigger radius.
Thanks

 

[FlashKat]

Try doing a slow manual feed to see if you still get the grooves. It almost sounds like you have set on a threading feed set-up.
Other possibility is you have play in your feed carriage.

No the grooves widened as the feedrate was increased... With changing speeds for any given feedrate, the grooves remain the same.

I'll try a bigger radius.
Thanks