[CadRhino]

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

[SCzEngrgGroup]

Have you tried taking multiple finish passes, including a final "spring pass"?

Regards,
Ray L.

[CadRhino]

Hi Ray,

Only on the corner round did I do a finish pass of .003" and I still have those lines.

Good suggestion (I should have done it on the rest of the ops but they are not visible).

I was just expecting overall better finish.

I will add a .003" finish pass to the other ops and that will probably help but I suspect I will still get the lines (just finer).

Thanks,

-Nathan

Have you tried taking multiple finish passes, including a final "spring pass"?

Regards,
Ray L.

[SCzEngrgGroup]

Hi Ray,

Only on the corner round did I do a finish pass of .003" and I still have those lines.

Good suggestion (I should have done it on the rest of the ops but they are not visible).

I was just expecting overall better finish.

I will add a .003" finish pass to the other ops and that will probably help but I suspect I will still get the lines (just finer).

Thanks,

-Nathan

Try taking a heavier finish pass. At 0.003", you may be rubbing. Cutting tools like to have a good "bite", and will often cut better when working harder. My typical finish cut is 0.01". Try both slowing down, and speeding up, feedrate. Depending on conditions, either one can improve finish.

I don't know what the quality of the Tormach endmills is, but the specific tool makes a HUGE difference. Those may simply not be very good endmills.

Regards,
Ray L.

[kfriedrich66]

Try taking a heavier finish pass. At 0.003", you may be rubbing. Cutting tools like to have a good "bite", and will often cut better when working harder. My typical finish cut is 0.01". Try both slowing down, and speeding up, feedrate. Depending on conditions, either one can improve finish.

I don't know what the quality of the Tormach endmills is, but the specific tool makes a HUGE difference. Those may simply not be very good endmills.

Regards,
Ray L.

Umm this contradicts your "spring pass" suggestion earlier which would be removing a minute amount of material and more than likely leave a worse finish.

Nathan, are you using a finishing endmill, 4 flutes or better for your finish work?
Kate

[CadRhino]

Hi Kate,
I am using the same tool for rough and finish so I am not switching over to a 4fl for finish but I will do that.
It is the chamfering and corner rounding that is getting me. Those are 4 flute and I was hoping for a better (mirror) finish but maybe, like popspipes said, it will always have some lines.
Ray's, comments kind of mesh with what Frank Mari (Mari tools) told me today. He said I might want to try 2000 rpm and 30 IPM and mix it up. That my machine might be having a funny 'harmonics' at 5100 RPM and that I might want to find the sweat spot for each too.
Best,
Nathan

Umm this contradicts your "spring pass" suggestion earlier which would be removing a minute amount of material and more than likely leave a worse finish.

Nathan, are you using a finishing endmill, 4 flutes or better for your finish work?
Kate

[SCzEngrgGroup]

Umm this contradicts your "spring pass" suggestion earlier which would be removing a minute amount of material and more than likely leave a worse finish.

Nathan, are you using a finishing endmill, 4 flutes or better for your finish work?
Kate

The point, is, you have to try different things. There are countless factors that can affect finish quality, and some can only be found by experimentation. Feeds and speeds that work well on one machine, may be awful on another, due to small differences in the cutting tool geometry, or machine or tool resonances. Even a small change in RPM can sometimes have a large effect. But, in general, tools are happier with a higher chipload. That can be achieved by reducing RPM, or increasing feedrate. If all is perfect, a spring pass can help, otherwise, it might hurt. You just have to experiment, and find what works best for you, with your tool, on your machine. For me, 3-flute tools are rarely an improvement. For others, they are. I also generally get better finish with a 2-flute than with a 4- or even 6-flute. Go figure...

Regards,
Ray L.

[popspipes]

Machine marks will always be present, they get smaller with lower feedrates but never completely go away as they are a function of the cutting action of the cutter.
I always take a finish pass on everything of .005 to .01, it does improve the finish.
I also have a vibrator finisher with walnut hulls and emery grit mixed with it that works to brighten parts up,

I finish at 5140 rpm and 20 to 35 feedrate but the spindle and drive are balanced pretty well so the finish is better but I still have the marks, they are just more even.

I also use 4 flute cutters for finishing.

[CadRhino]

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

Machine marks will always be present, they get smaller with lower feedrates but never completely go away as they are a function of the cutting action of the cutter.
I always take a finish pass on everything of .005 to .01, it does improve the finish.
I also have a vibrator finisher with walnut hulls and emery grit mixed with it that works to brighten parts up,

I finish at 5140 rpm and 20 to 35 feedrate but the spindle and drive are balanced pretty well so the finish is better but I still have the marks, they are just more even.

I also use 4 flute cutters for finishing.

[SCzEngrgGroup]

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 shells will not take of machining marks unless maybe if you leave them in there for an eternity (days, if not weeks). Plastic pyramids (which must be used wet) will remove machining marks in 1-2 hours, leaving the surface looking like it was media blasted. It will also remove burrs, and put a very small radius on all the edges. You can then polish it using ceramic balls or rods with a fine abrasive (dry), and finish polish with walnut shells and rouge. But the last two polishing steps will still take a day, perhaps two. And, you can't put a lot of parts in each run, or they'll scratch each other up.

Regards,
Ray L.

[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!!

[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!!

[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.

[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.

[pickled]

Agreed with the comments above. The other piece to verify is that you are at the shortest stick-out of the tool that you can get for your set-up. I typically only give my tools a reserve of about 0.015" in length to get a high finish job done. Expensive carbide tooling is nicer in this regard, but it even likes to be choked up a bit in the holders. Your radius cutter did quite well and a little bit of hand finish or walnut lovin' should make that area shine. What DOC were you using for your chamfer and how high was your contact point?

[CadRhino]

I had the chamfer up .02" and added another fudge factor of .02" stock to the chamfer so it was .03" up from the tip of the chamfer tool. I use sprutcam so that is the formula I used so it was not cutting on the tip.

Agreed with the comments above. The other piece to verify is that you are at the shortest stick-out of the tool that you can get for your set-up. I typically only give my tools a reserve of about 0.015" in length to get a high finish job done. Expensive carbide tooling is nicer in this regard, but it even likes to be choked up a bit in the holders. Your radius cutter did quite well and a little bit of hand finish or walnut lovin' should make that area shine. What DOC were you using for your chamfer and how high was your contact point?

[MichaelHenry]

To me, it would be a lot easier (and faster) to get a good finish on parts like that with a lathe, either CNC or manual. If a dull matte finish, rather than bright, is acceptable than you might try tumbling the mill-machined parts.

Mike

On edit: Using the Tormach as a lathe, as others here have shown, might also be a good solution.

[CadRhino]

Agreed but I am going to be doing quite a bit of work on the back sides and I only have a manual lathe which I am not terribly fast on.

To me, it would be a lot easier (and faster) to get a good finish on parts like that with a lathe, either CNC or manual. If a dull matte finish, rather than bright, is acceptable than you might try tumbling the mill-machined parts.

Mike

On edit: Using the Tormach as a lathe, as others here have shown, might also be a good solution.

[CadRhino]

I would love to start using my mill as a lathe but since I am using the tts system (and atc) I think the best I could do is to put a 1/2" diameter into a 1/2" tool holder.
If I didn't have the atc and PDB I could put a r8 chuck in the spindle. Do you know if any alternates ways?
Thanks

To me, it would be a lot easier (and faster) to get a good finish on parts like that with a lathe, either CNC or manual. If a dull matte finish, rather than bright, is acceptable than you might try tumbling the mill-machined parts.

Mike

On edit: Using the Tormach as a lathe, as others here have shown, might also be a good solution.

[MichaelHenry]

I would love to start using my mill as a lathe but since I am using the tts system (and atc) I think the best I could do is to put a 1/2" diameter into a 1/2" tool holder.
If I didn't have the atc and PDB I could put a r8 chuck in the spindle. Do you know if any alternates ways?
Thanks

You can still put an R8 chuck in the spindle, it will just be more hassle. That is more hassle than I want to put up with so the Slant Bed Lathe is probably in my future.

Mike