Milling Brass - Mess Mitigation - Success/Failure - And Questions

[Ziggy]

Hello

This is my first foray into cutting metal with the Onefinity so please forgive my lack of experience.

I don’t see myself cutting metal very much. However I wanted to make some brass inlays.

I didn’t want to ruin my spoilboards with cutting fluid. I also didn’t want brass chips getting into the lead screws if I could help it.

So I did a little work in Fusion and came up with an – admittedly – probably overkill solution.

My idea is to have a flat(ish) tray where I can screw down sacrificial plates to which I have glued sheets of metal. In addition, I wanted to keep the chips that shoot up out of the lead screws as best as I can so I made a shield that attaches to the Suckit arms.

Here is the tray.

Here is a piece of brass Superglued to a 3D printed spoil plate

I reasoned that once the milling is done that I could immerse the 3D print and brass into acetone and let it sit overnight. More on this later.

I posted a couple of videos of the milling operation to YT.

This brings ups a question/concern. Is that “clunking” sound normal? It seems to happen when there are sudden movements. Normally I have dust collection running so I wouldn’t have heard it. Is there a setting in Fusion CAM that tells it to make the transitions more gently?

Also, I think I have my ramp too steep.

Here are the videos.

Video 1

Video 2

Takeaways:

The idea worked for the most part but wasn’t entirely successful.

I realized that I didn’t need to make such a large hole for the chip shield since I would be using shorter milling bits and the spindle would never need to pass through. I’ll make one with a hole just big enough for the collet. Easy enough.

The biggest failure is that the spoil plate failed. I think using an upcut bit caused the top layer to lift and it ruined a couple of my parts. (See Below) I will try printing another with 100% infill and using a downcut bit, If that doesn’t work I may search for a different substrate.

The part on the left was fine. the part on the right lifted and the side of the cutter ate away part of the “C.”

Soaking the parts in acetone worked but also had some downsides. It caused the PLA to warp and twist to the point I was afraid it would bend my parts. So I had to pull everything out and gently cut around my parts. After letting them soak overnight they came out clean.

To be honest, I don’t like the fumes of the Superglue and I don’t like the mess of the acetone. I am considering using Hideglue to attach the workpiece to the spoil plate. That can be soaked in water to release the part… theoretically. My only worry is that the hideglue might not be strong enough to deal with the milling especially after being squirted with water based cutting fluid.

So… any ideas or suggestions?

Also, please let me know if that clunking sound is normal. It is a bit worrisome.

[AndyP (Badger)]

I have come across someone who makes steel clock hands and superglues the steel directly to a piece of machined Aluminium and uses a solvent to soften the superglue once the hand is cut. I haven’t tried it myself.

[Hermsen.BJ (BJ Hermsen)]

I found that super glue did not mix well with cutting oil and/or the heat that soaked into bread when I tried that…but it may have been me and my feeds and speeds

[SurfinGump (Forrest)]

I purchased a mist coolant block and nozzle (https://www.amazon.com/gp/product/B07HT1Y4BK), which I attached to the laser mounting screw holes, and used isopropyl alcohol (IPA) as my coolant/lubricant. While it primarily functions as a coolant, I like to think it provides some degree of lubrication as well.

The brass blanks were sourced from Send Cut Send (highly recommended). I secured them into a jig made from a scrap piece of wood, using a combination of blue tape and super glue. As long as I didn’t flood the piece with too much IPA and kept it to a barely noticeable “fog,” the tape and glue did an excellent job of holding the brass firmly to the MDF jig.

One of the advantages of using IPA is that it evaporates extremely quickly and doesn’t damage the wooden jig. By keeping the airflow at about 20-25 psi, I found it was enough to blow the brass chips clear of the bit.

The downside, though, is that the brass chips still get EVERYWHERE. Even with a dust boot and the misting nozzle working together, tiny pieces of brass seemed to fly into every corner! I had to be meticulous about vacuuming and cleaning up after each carving, and often during the carving process as well. Despite my efforts, I still ended up with brass splinters (ouch!) for days after, even when I thought I had thoroughly cleaned everything up.

Given the constant cleanup required and the fact that I was working on extremely detailed 3D carvings on relatively small pieces (~4-inch tall blanks), I’ve decided to scale back on these projects. Mass production of these intricate 3D carvings is simply too time-consuming and prone to scratches caused by the bit and/or chips getting in the way, so I’ll likely only do them for special occasions moving forward.

I hope this post helps someone considering brass carving! Photos, videos, and details on feeds and speeds to follow below.

Toolpaths:

3D Roughing 1
Powertec 1/8" 2FL Up Cut End Mill
1 mm Boundary Offset
0.5 mm Machining Allowance
3D Raster mode
Avoid machine areas: checked
Raster angle: 0 degrees
18,000 RPM
750 mm/min
750 mm/min plunge
40% stepover
0.0295 INCHES pass depth

3D Roughing 2
BitsBits 4TEB10-062-2FL - 1/16" Tip 5° Tapered Ball Nose
1 mm Boundary Offset
0.1 mm Machining Allowance
3D Raster mode
Avoid machine areas: checked
Raster angle: 45 degrees
16,000 RPM
2000 mm/min
1000 mm/min plunge
8% stepover
0.025 INCHES pass depth

3D Finish
Lakeshore Carbide 020ENG14-20DG-DE-N3 (20.0°, Tip 0.508mm - 6.35 mm)
1 mm Boundary Offset
3D Raster mode
Raster angle: 0 degrees
18,000 RPM
2000 mm/min
2000 mm/min plunge
8% stepover

[Machinist (Bill Blades)]

@SurfinGump

I had to be meticulous about vacuuming and cleaning up after each carving, and often during the carving process as well. Despite my efforts, I still ended up with brass splinters (ouch!) for days after, even when I thought I had thoroughly cleaned everything up.

Wow, welcome to my world when I cut aluminum (which is why I generally don’t do it very often). And when I use cutting fluid, it doesn’t clean up as well but it helps the cuts tremendously.

@Ziggy

Also, please let me know if that clunking sound is normal. It is a bit worrisome.

I don’t believe that’s anything to worry about, it sounds pretty typical to me. The cutter is always under a certain amount of preload when cutting, and that sound may just be the cutter ‘settling in’ to it’s new temporary stopping point.

@Ziggy

and using a downcut bit

Downcut bits may be great for wood, but in general, they create more cutting pressure on the workpiece. I think surface finish will suffer and the additional cutting pressure/heat may tend to warp the part. Your mileage may vary on the downcut bit though, as I learned as a machinist that brass doesn’t always play by the same machining rules as other metals.

[Ziggy]

Thanks for all the replies!

It is really appreciated. Especially the advice about the downcut and the tool paths.

These are all thru cuts on 20 gauge brass. Basically this project is just a “first pancake.” I am using it to learn.