# Making a Part Look Pretty



## ddickey (Jan 19, 2017)

Especially milled parts. I have milling marks everywhere. Not sure if this is normal but what would be the process of making parts look nice. File, sanding, polishing. How do I decided how to go about this?


----------



## Ulma Doctor (Jan 19, 2017)

different materials will machine differently and the leftover marks will vary
some materials you need to intentionally leave a little large and grind or otherwise finish to final dimension
softer materials can use cutters spinning at higher speeds with an end finish that will appear less flawed
sometimes tool geometry is critical to a good finish as is feed rate and RPM

a lot of production parts are tumbled in vibratory finishers for brilliant finishes
perhaps a homebrew tumbler may be something to consider.
walnut hulls, almond hulls, ceramic media, and sand/gravel could be used to different levels of polish
then there is always sanding and polishing with elbow grease and polishing compounds too


----------



## Wreck™Wreck (Jan 19, 2017)

Handwork, polish until the desired results are achieved.

Electro polishing is an option but I suspect that you would not like the cost, a timesaver is also helpful before starting the work, otherwise the tooling marks are part of the game.


----------



## chips&more (Jan 19, 2017)

Maybe do the last pass with only a few thousandths of material removal and a higher spindle speed. Also, you should always conventional mill. But, on that last pass maybe return with a climb cut with no cut intended. Just return the cutter to the beginning in a climb cut...Dave


----------



## jlsmithseven (Jan 19, 2017)

If you really want it shiny, go take it to the surface grinder. Make sure you leave a couple extra thousandths to take off after your done milling.


----------



## intjonmiller (Jan 19, 2017)

It depends ENTIRELY on what you're doing. As Ulma Doctor said, the tool geometry matters. The feeds and speeds matter (higher speed and slower feed, for instance, will generally produce a finer finish, all else being equal). The materials matter. The shape you're producing matters. A well-tuned surface grinder can make your parts incredibly smooth and shiny when done right...if your part involves all flat surfaces to allow it to be surface ground. 

Generally hand finishing is an excellent option for most projects. Not always the most efficient, if resources were unlimited, but always effective. Check out Tom Lipton's (Oxtoolco on YouTube) completed Baby Bullet Vise series for an excellent demonstration of all the different aspects of producing an incredible finished part. His ongoing series on building an intaglio printing press is also very good. Many other such projects out there. But the absolute best I am aware of is Clickspring's recently completed clock project. It took him almost two years to make it, and every minute of every one of his videos is enjoyable and educational. 

See you next week.


----------



## ddickey (Jan 19, 2017)

I believe I'm using the correct speed not sure about the feed. My mill is manual so I normally feed slowly no matter what the speed. Can to slow a feed with the correct speed contribute to a poor finish?
Thanks for the tips guys.


----------



## Chipper5783 (Jan 19, 2017)

Practice, try again, read about material properties/tool geometry/speeds/feeds, practice, talk to machinists, practice, ask questions here - try, try again.  I don't think there is any magic recipe to getting a good surface finish as machined.  All the above ideas are good - but you need to simply keep at it.


----------



## tq60 (Jan 19, 2017)

If a mill then depth of cut and speed of feed as well as consistency of feed meaning power feed will be much better than manual.

Good sharp tools and a perfectly trimmed head.

If it is not perfectly straight then the cutter will not cut flat and will never De good in less you are cutting a cove.

Sent from my SAMSUNG-SGH-I337Z using Tapatalk


----------



## Subwayrocket (Jan 19, 2017)

I often use the first few passes to get the speed dialed in . Feeding by hand would make it more difficult to be consistent . Too slow feed or too shallow cut and it rubs , too fast and you get lines . I usually have an idea where i wana be , then tweak it as the first pass is feeding across . Scotch brite wheels and Roloc discs work well in steels and the lambs wool wheels do good in Alum . I've put them in a hand drill .


----------



## T Bredehoft (Jan 20, 2017)

It it's nothing but flat surfaces, lightly belt sand it to make it a bit flatter then jewel it. put a 3/8 wooden dowel in the mill, dab some lapping compound on the surface and spot it every  1/4 inch in each direction. Time consuming, yes, but you will have a beautiful finish.


----------



## intjonmiller (Jan 20, 2017)

Yes, too slow feed can be detrimental because it can't "bite" in and turn a chip, so it rubs. 

The book "Manual of Lathe Operations", distributed by Atlas once upon a time, has the best explanation I've found for understanding how the tooling is working, regardless of the type of tool or machine, because they first get into metalworking theory. (The horrendously short version: every tool used to cut metal is a variation on a cold chisel.) There are also a number of old machining videos (like 1940s-1960s stuff) on YouTube that show what's happening very well. I'll try to find you some links. There are certain little lessons that just "click" when you see these concepts presented in just the right way, even though you had read explanations or seen videos of the tools used before.


----------



## intjonmiller (Jan 20, 2017)

This is a VERY recent video on tool bit grinding, which has some good information about the effects of different elements of the tool bit geometry.


----------



## intjonmiller (Jan 20, 2017)

And here's a thread where I shared the oldschool videos I was referring to: http://www.hobby-machinist.com/threads/tooling-geometry-intro-video.48055/


----------



## mikey (Jan 20, 2017)

In my opinion, the first step toward a good finish is to cut it clean in the first place. Use a fly cutter to square the part, not an end mill. Then rough your features with a roughing end mill before using a good finishing end mill. Your parts will need minimal clean up and final finishing will be much easier.


----------



## ch2co (Jan 20, 2017)

I don't know what mill you are using or just how much experience you have in milling, but a few things that I have learned either by listening to the guys here on The Hobby-Machinist or by hit and miss experimentation: What kid of a mill are you using. What kind of cutter are you using. Cutter RPM? Speed of feed?  Lubricant? and possibly the most important that I have found is: are you firmly locking all axis that you are not using for the particular cut. Have you trammed your mill head and table?
SAs for final finish, I usually use  3M Scotchbrite pads which I have on hand in every conceivable size, form shape, and grit.  I really like the ideas of the wooden dwell/lapping compound and lambs wool wheels mentioned above, as well as the tumbling and or vibration of the part in various media like walnut shells.  Thanks for starting this discussion up, I'm picking up all sorts of new idea. 
Let us know what you did up doing and show us some pictures of the before and after results.

CHuck the grumpy old guy


----------



## ddickey (Jan 20, 2017)

I have an older Grizzly 1004 I think it is. It came with a ton of end mills and other cutters, some where even new. It came with a fly cutter that cuts horrible. The cutting tool looks poor so my guess is it is the wrong geometry, sharp with no radius. I tried to hand grind some into it but didn't make much of a difference. It also came with what looks like a carbide fly cutter which has four cutting non removable inserts, at least they look non removable. This tool leaves a relatively smooth cut but lots of cutting marks which I'm learning is probably normal. Speeds were low. Anything more than a few thou DOC and my mill makes a horrible racket with those big cutters. The mill performs well with smaller end mills. I trammed it when I got it home. I should probably check it again though.


----------



## ddickey (Jan 21, 2017)

Here's that face mill. Those cutters are permanent or?


----------



## Ulma Doctor (Jan 21, 2017)

Hi ddickey,
the cutters appear to be brazed in place by the manufacturer.
conceivably, they could be replaced if you had the need or inclination.
set up would need to be fairly precise to get the cutters in the same plane of height, but not too a big hurdle


----------



## dulltool17 (Jan 21, 2017)

Actually, with a bit of ingenuity, I'd be willing to bet you could modify that cutter to hold inserted tool bits!


----------



## mikey (Jan 21, 2017)

It might be time to make or buy a flycutter. WreckWreck turned us on to the B-52: http://www.kristitool.com/b-52-fly-cutter/

The B-52 can run at high speeds, uses a single inserted carbide tip and can cut to a shoulder, which is a big advantage. Not cheap but it looks good.

Another option is the Tormach Superfly: https://www.tormach.com/store/index.php?app=ecom&ns=prodshow&ref=32428

The Superfly also uses inserts and cuts a clean, flat surface. Finish is acceptable but not a mirror finish. Can be run at high speeds and is half the cost of a B-52. It cannot cut to a shoulder, which is a disadvantage but it will cut a very flat, even surface. I own this one at the moment.

You can also make your own head to take a LH HSS flycutting tool. 

Or you can make a head to accept a Superfly arm or a Suburban Tool flycutter arm. All of these will be faster than a shell mill and potentially will produce a finish that is as good or better than a shell mill. They all use only a single insert. The carbide cutters will also run at the max speed of your mill, enhancing finishes, and all can run with low HP motors.

That old brazed carbide shell mill has a socket head screw underneath so I suspect the cutter head can be replaced. Personally, I would go with a fly cutter. If you have the HP, that B-52 can take a o.100" bite so it can do stock removal, too.


----------



## Chipper5783 (Jan 21, 2017)

Hi ddickey, that is strangest looking "face" mill I have ever seen.  Perhaps it is some sort of special purpose industrial cuter, originally used on a horizontal mill?  I get it that you found the fly cutter gave you horrible results - but mikey has given you some good advice to work a little harder with the fly cutter.  I recently made up some short sections of rail road steel for a display, cut on the power hacksaw and then fly cut on the mill - the finish was very good (I have not cut rail road rail before, I found this to be quite tough material).

I tilted the head slightly off tram, so that the trailing side of the fly cutter did not drag (this is for a display the very shallow dish is not a problem) and I found I could only take about 0.005" depth of cut - though I could feed fairly fast, but then the finish deteriorated.  For the nice finish I ended up using my slowest table speed (0.75"/min).  I found that I would only get 3 passes before needing to regrind (using brazed carbide).  You should see from these last couple sentences that it was a trial/error process - making a few cuts and just seeing what worked.

For the attached pictures, the cut was about 6" wide, using a boring/facing head, I had everything pulled in or set up as close as possible and everything locked tight.  Although the machine is a Cinci knee mill with a #40 taper - which gives more mass and stiffness than the G1004, you should still be able to get good results with what you have.  Keep working at it.


----------



## ddickey (Jan 21, 2017)

Looks really nice Chipper5783. What was the display for?
Mikey, I see a few home made fly cutters out there. I think I'll attempt to make one and use that Superfly bar.
Thanks for the info guys'


----------



## mikey (Jan 21, 2017)

ddickey said:


> Looks really nice Chipper5783. What was the display for?
> Mikey, I see a few home made fly cutters out there. I think I'll attempt to make one and use that Superfly bar.
> Thanks for the info guys'



If you make one to take the Superfly bar, it is held at a 19 degree down angle from the head.


----------



## ddickey (Jan 21, 2017)

Thanks Mike.


----------



## cathead (Jan 21, 2017)

A fly cutter set up properly with a carefully trammed mill will be so smooth that you can't feel or really see
the machining marks.  A single point fly cutter is superior to any multi toothed tool for a smooth surface.
I know a somewhat larger radius is supposed to better for a smooth surface but I am getting good
results with a right hand 1/2 inch carbide with a pretty tight radius.  I have yet to try the recommended
radius on the tool. 




It takes a bit of practice with cutter geometry and feeds and speeds to get it right.  I'm still
experimenting but happy with the results so far.  The bottom of the photo is of a piece of
mild steel milled with the above cutter.


----------



## Chipper5783 (Jan 21, 2017)

ddickey said:


> Looks really nice Chipper5783. What was the display for?


I'm part of a train club.  The idea is to put together a display showing a bunch of different weights of rail.


----------



## kd4gij (Jan 22, 2017)

If it is not a decretive part. I hit it with the blast cabinet.


----------



## Kroll (Jan 22, 2017)

After you get the right cutting tool,I use a deburring wheel to polish to a shine.Warning,the wheel will remove finger hide quickly----kroll


----------



## ddickey (Jan 22, 2017)

A scotchbrite wheel?


----------



## ch2co (Jan 22, 2017)

Scotch Brite isn't just hand pads.   
http://solutions.3m.com/wps/portal/...d-Pads/?Ntt=scotch+brite+wheels&rt=rs&x=0&y=0


----------



## OlBull (Feb 2, 2017)

A buffing wheel can be an important tool also if you are looking for a shiny finish, especially on aluminum.


----------



## tq60 (Feb 2, 2017)

That shell mill is what comes with the hf and other mills and it is okay for some work but not much.



Sent from my SAMSUNG-SGH-I337Z using Tapatalk


----------



## m2salmon (Feb 17, 2017)

For flat surfaces, you can sand/lap the surfaces using progressively finer wet/dry sandpaper then grades of scotchbrite pads.  Rub the part in figure 8 pattern and machining marks will quickly disappear. Use a piece of glass or cheap 9x12 granite surface plate as the flat surface you tape the abrasive paper or scotchbrite to. You can get close to a mirror finish this way.  For round parts, finish with emory cloth then scotchbrite in the lathe. A 1x42 belt sander with scotchbrite belt is also a great finishing tool.


----------



## Kroll (Feb 18, 2017)

Sorry bout not responding back sooner,this is such a neat topic but yes to the question which I went to the link above---
http://solutions.3m.com/wps/portal/...L-Deburring-Wheel?N=7581697+3293241548&rt=rud
This wheel is amazing but again it will remove material and skin if you want it to.


----------

