[pickled]

Pyramids are quick. Walnut and corn in a simple tumbler do pretty well for me when smoothing over 6061 and 7075. They will not remove scallops, but surface marks tend to drop off quite well. Yes it does take 1-2 days, but I don't have to worry about dimensional changes when I leave my parts in and forget about them- thankfully. They do not remove burrs and you better plug any holes that you have tapped or plan on tapping!

[popspipes]

Hi Popspipes,
Thanks for the insight.
I have a Harbor Freight vibrator I have not used yet so this may be a good reason to get it set up.
What kind of Walnut shell and grit do you use and where do you get it?
Thanks for the feedback on feeds and using a 4 flute for finish passes. I have 2 flute beaten into my head for aluminum but that makes sense.
Best,
Nathan

walnut shell I got from Harbor Freight, the emery I had from years ago, It can be bought at a supplier that handles polishing grits.
Machining only goes so far, the marks get smaller but never all go away, If I were going to polish the radius on that part I would put it in the lathe max spindle speed and use a 3 m metal finishing wheel mounted on an angle grinder at reduced rpm, a few minutes of this will give it a matte finish and will remove the tool marks, if you need a mirror finish, go to jewlers rouge or emery and a rag wheel. All polishing takes some time, the more mirror finishes take the most time.

Most of my aluminum work doesnt need polishing as the guys that buy it want to see the machine marks, they just have to look nice and not have any burrs.

I have used many 3m polishing wheels on stainless parts and piping, they are the best period, that I have found, also the most expensive.
The most even way I have found to polish a part is to rotate it (lathe) and use a rotating 3m wheel on an angle grinder at reduced speed. I never did much aluminum polishing except for my hobby parts, most of mine was done on stainless tanks and piping.
Those 3m wheels I used work equally well on aluminum, it just cuts much faster than stainless.

There are many ways of doing it, you just have to find the way that suits you.

3M sells many wheels for metal finishing, the one I used mostly was a 2S FN 6" or 8" x 1/2" x 1"arbor hole, the last ones I bought were around 60 dollars each, that was almost 10 years ago.

I would say that buffing that part in the lathe would take less than 10 minutes on the radiused end only, if its aluminum, once you get the hang of it.

a piece of emery paoer would do the job on the lathe as well but would take longer, and is a bit more work.

I am kind of new to the vibratory finishers, and I am sure there are better ways than mine, I just dont know what they are ha!!

[Machinehead57]

I have found that using a commercial router bit which has the 1/2" shank leaves a very nice finish on soft metals. They are extremely sharp well shaped and maintain this for a long time. One other thing never use a cutter on soft metal once used in steel, you will get the ugliest finish you ever saw. These router bit can be bought at most home supply stores in beveled corner rounding in various radius and so on.

Good luck
Steve

[Steve Seebold]

You can get walnut shell with rouge at your local gun shop. It's primarily used for polishing brass for reloading. I use it to polish some of the aluminum parts I make for my model boat running gear. It had absolutely no debarring qualities. I use it only for polishing. I have 2 Burr King vibratory tumblers. One is a 3 quart and one is a 10 quart. I use the 10 quart one for debuting and the 3 quart one for polishing. When I put parts in the polishing media, they will often run for up to a full week.

[CadRhino]

Thanks for the insight, Steve
It makes me a little nervous using a carbide wood bit on my tormach but I will try it. Do you think it would give a better finish than the round over profile I showed?
Thanks

I have found that using a commercial router bit which has the 1/2" shank leaves a very nice finish on soft metals. They are extremely sharp well shaped and maintain this for a long time. One other thing never use a cutter on soft metal once used in steel, you will get the ugliest finish you ever saw. These router bit can be bought at most home supply stores in beveled corner rounding in various radius and so on.

Good luck
Steve

[300sniper]

How many do you have to do?

[CadRhino]

I have thought about chucking the parts on my metal lathe to sand/buff them but the thought that was getting any grit in my ways always stops me. I know I can clean it up every time but just a little grit missed could wreck havoc on the ways.
I have a wood lathe I might try it on.
How do you hold the demurring wheel when it is on your lathe or do you use it on a seperate tool?
Thanks

walnut shell I got from Harbor Freight, the emery I had from years ago, It can be bought at a supplier that handles polishing grits.
Machining only goes so far, the marks get smaller but never all go away, If I were going to polish the radius on that part I would put it in the lathe max spindle speed and use a 3 m metal finishing wheel mounted on an angle grinder at reduced rpm, a few minutes of this will give it a matte finish and will remove the tool marks, if you need a mirror finish, go to jewlers rouge or emery and a rag wheel. All polishing takes some time, the more mirror finishes take the most time.

Most of my aluminum work doesnt need polishing as the guys that buy it want to see the machine marks, they just have to look nice and not have any burrs.

I have used many 3m polishing wheels on stainless parts and piping, they are the best period, that I have found, also the most expensive.
The most even way I have found to polish a part is to rotate it (lathe) and use a rotating 3m wheel on an angle grinder at reduced speed. I never did much aluminum polishing except for my hobby parts, most of mine was done on stainless tanks and piping.
Those 3m wheels I used work equally well on aluminum, it just cuts much faster than stainless.

There are many ways of doing it, you just have to find the way that suits you.

3M sells many wheels for metal finishing, the one I used mostly was a 2S FN 6" or 8" x 1/2" x 1"arbor hole, the last ones I bought were around 60 dollars each, that was almost 10 years ago.

I would say that buffing that part in the lathe would take less than 10 minutes on the radiused end only, if its aluminum, once you get the hang of it.

a piece of emery paoer would do the job on the lathe as well but would take longer, and is a bit more work.

I am kind of new to the vibratory finishers, and I am sure there are better ways than mine, I just dont know what they are ha!!

[mountaindew]

Thanks for the insight, Steve
It makes me a little nervous using a carbide wood bit on my tormach but I will try it. Do you think it would give a better finish than the round over profile I showed?
Thanks

I use 2 flute solid carbide spiral up-cut, down-cut and compression cut router bits on aluminum, plastic and wood and find in many cases they work very well. The main reason I use them is they are long and cut to depths of 1.5" or more where many standard end mills are to short for this . White side makes some of the best in my opinion and you will pay for this. At $50-$80 each they don't come cheap. On the other hand if used with care they will last a very long time. btw If you want the best finish possible of acrylic these are awesome and blow away most any other tool that I have ever tried.
md

[popspipes]

I have thought about chucking the parts on my metal lathe to sand/buff them but the thought that was getting any grit in my ways always stops me. I know I can clean it up every time but just a little grit missed could wreck havoc on the ways.
I have a wood lathe I might try it on.
How do you hold the demurring wheel when it is on your lathe or do you use it on a seperate tool?
Thanks

I made adapter bushings for the angle grinders, 5/8 x 11 thread in one piece and a 1" od, then a cup for it to fit into, when its hand tightened it will clamp the sheel in the arbor. Its kind of a homemade thing I concocted years ago. I had 8 of these grinders with various adapters on each for what I used im my line of work.


I can try to post pictures if your interested.

[CadRhino]

Thanks for the offer Popspipes but I think I am going to play with different cutters/ speeds and try your vibrator suggestion with walnut shells first.
Nathan

I made adapter bushings for the angle grinders, 5/8 x 11 thread in one piece and a 1" od, then a cup for it to fit into, when its hand tightened it will clamp the sheel in the arbor. Its kind of a homemade thing I concocted years ago. I had 8 of these grinders with various adapters on each for what I used im my line of work.


I can try to post pictures if your interested.

[CadRhino]

Thanks for the insight md
I have seen some if your acrylic work and it is very nice.
Do you also use your spiral flutes on aluminum?
I have a bunch of spiral up/downs I use on my routers but never considered them for aluminum.
Nathan

I use 2 flute solid carbide spiral up-cut, down-cut and compression cut router bits on aluminum, plastic and wood and find in many cases they work very well. The main reason I use them is they are long and cut to depths of 1.5" or more where many standard end mills are to short for this . White side makes some of the best in my opinion and you will pay for this. At $50-$80 each they don't come cheap. On the other hand if used with care they will last a very long time. btw If you want the best finish possible of acrylic these are awesome and blow away most any other tool that I have ever tried.
md

[mountaindew]

Thanks for the insight md
I have seen some if your acrylic work and it is very nice.
Do you also use your spiral flutes on aluminum?
I have a bunch of spiral up/downs I use on my routers but never considered them for aluminum.
Nathan

Mostly as I mentioned above for long reach operations in aluminum and plastic. They work well for finish operations also. I have these setup with a great deal of overhang and would not push them hard because tool deflection is easy to see.
md

[Machinehead57]

The router bit with 1/2" shanks work great in a mill the 1/4" ones are to week to do much but will work if used lightly. A straight cut router bit is the best way I have found to re-spline hardened axle shafts. But yeah I think it will, do the spring cut as a final pass and use conventional milling not climb. The climb will leave little straight marks like you are getting. The extremely sharp edge of the wood bit can take the smallest of cut cleanly high spindle speed with slow travel works best. Experiment some on a piece of scrap and find the combo that works best with your setup.
You would be surprised to find what can be used in a mill. I have used a fine toothed carbide tipped 7 1/4" skillsaw blades to make deep undercuts or slice off thin layers of a profiled piece.

Good luck
Steve

[CadRhino]

Thanks for the insights, Steve

The router bit with 1/2" shanks work great in a mill the 1/4" ones are to week to do much but will work if used lightly. A straight cut router bit is the best way I have found to re-spline hardened axle shafts. But yeah I think it will, do the spring cut as a final pass and use conventional milling not climb. The climb will leave little straight marks like you are getting. The extremely sharp edge of the wood bit can take the smallest of cut cleanly high spindle speed with slow travel works best. Experiment some on a piece of scrap and find the combo that works best with your setup.
You would be surprised to find what can be used in a mill. I have used a fine toothed carbide tipped 7 1/4" skillsaw blades to make deep undercuts or slice off thin layers of a profiled piece.

Good luck
Steve

[popspipes]

Hi Fellow Tormachers,

I am making a run of these parts in 6061 aluminum and I am not really happy with my finish results so far.
The non-corner rounded part is held .2" deep in a vise very snugly and the corner rounded side is held .5" deep very firmly in a vise.
As you can see from the photos, there are lots of tiny vertical lines left over from the cutters.
Here is what I am using;
1) Main cutting (on vertical sides) is a Tormach 1/4" HSS E.M. in an ER20 collet at 5100 RPM and 12 IPM.
2) Chamfering is done with Maritool 1/4" 4-flute carbide cutter in 1/4" dia. tool holder 5100 RPM and 12 IPM.
3) Corner round is done with Maritool .187 radius 4-flute carbide cutter in 1/2" dia. tool holder running at 5100 RPM and 5 IPM.

I originally cut the corner round at 5100 RPM and 12 IPM but it had the same line issue so I reduced the feed to 5 IPM and it is better but as you can see it still has a bunch of small vertical lines from the cutter.

Any thoughts on what might be happening or how I can get a better finish? Change the speeds/Feeds?
If just one of the tools was having this issue I would think it was that particular tool but all of the tools are creating these lines in surface finish.

I have some Lake Shore carbide 1/4" 2-flute EM's coming to see if they are better but I need to stick with the MariTool profile cutters for now.

Thanks,
Nathan

One of my mentors told me when I was learning machining, that a smooth file was used for fine finishes, I use that a lot as well, followed with some fine emery paper etc.
My circular cuts on the Tormach are not perfect either, the all have very short straight segments in them. There is a lot to be said for finishing in a lathe as the marks can be blended together rather easily, especially if dimensions are not super critical.

If the spindle and drive are not balanced really well, use an rpm that doesnt vibrate, that will make a big difference in the finish as well. Vibration transfers thru the whole machine and will be seen in the finish to some degree.
I do polish on the lathe, and it does have an adverse effect on the ways etc. Covering them with a cloth under the chuck helps with that.

[underthetire]

Looks like typical low spindle/holder rigidity issues as well as an unbalanced condition. Have a smart phone? Download a vibration app and place it on the machine. You'd be surprised how well something so simple can balance so well.

[CadRhino]

Thanks for clarifying, Popspipes. I can see how the vibration things translate. Each tool run has its own unique set of sounds and sometime a weird ticking noise that seems to come from the motor (fan blades).

Things are definitely not as simple as using Gwizard to set everything then your off.
I am going to go back and look at your posts on balancing your machine. I assume you had to take your motor housing off to access the fan to balance it.
I am still determined to find a more hands off solution but I did get my lathe fired up yesterday so I may look at that option closer if I need to.

Thanks
Nathan

One of my mentors told me when I was learning machining, that a smooth file was used for fine finishes, I use that a lot as well, followed with some fine emery paper etc.
My circular cuts on the Tormach are not perfect either, the all have very short straight segments in them. There is a lot to be said for finishing in a lathe as the marks can be blended together rather easily, especially if dimensions are not super critical.

If the spindle and drive are not balanced really well, use an rpm that doesnt vibrate, that will make a big difference in the finish as well. Vibration transfers thru the whole machine and will be seen in the finish to some degree.
I do polish on the lathe, and it does have an adverse effect on the ways etc. Covering them with a cloth under the chuck helps with that.

- - - Updated - - -

Thanks
I will look for one.

Looks like typical low spindle/holder rigidity issues as well as an unbalanced condition. Have a smart phone? Download a vibration app and place it on the machine. You'd be surprised how well something so simple can balance so well.

[adamvs]

A couple of ideas that might not have been mentioned: 1) if your client can go with 7075, instead of 6061, in my experience it machines much nicer. 2) If you have time to do a little hand finishing as a second op, #000 and #0000 steel wool do wonders on aluminum - it's a great deburring and semi polish.

[CadRhino]

Thanks for the insight, Adam.
I will toy with some 7075 in the future but all the material I have is 6061.
It would be cool to come up with a way to chuck up steel wool in a spindle and use that as a 'polishing' tool.

-Nathan

A couple of ideas that might not have been mentioned: 1) if your client can go with 7075, instead of 6061, in my experience it machines much nicer. 2) If you have time to do a little hand finishing as a second op, #000 and #0000 steel wool do wonders on aluminum - it's a great deburring and semi polish.

[victorofga]

try to lower acceleration in your control if that helps...
those marks don't looking resonance issue by tool or machine...

if your surface will be smoother then you save the extra time to finish by hand..
so a little extra time on machining might return you...