Machining Aluminum as a Beginner

Nomad
#1

Hi everyone,

I have a Nomad 3 and am new to machining. I’ve done successful runs on renshape, which is pretty much the easiest material but I really got the cnc to make simple aluminum molds. I tried machining a simple 2"x2" test block of 6061 and it worked but made really bad noise which I think is chatter but not sure. I am not sure if it is my settings / speeds and feeds or my workholding or both. I was wondering if anyone has a simple fusion 360 file maybe for squaring the block that I could test with Carbide’s 102Z drill bit?
Thank you so much! See also my workholding below, I used parallel bars to but put my block in the vise.

IMG_1547
IMG_15474032×3024 3.02 MB

#2

The coated #102Z will help a lot.

What feeds and speeds are you using?

Have you seen:

1 Like
#3

I didn’t end up having a lot of luck getting the vice to work for me. Not to say it wasn’t useful, I just didn’t have much luck with it. Recommend checking out either masking tape and superglue, tigerclaw (compact) and the lock stops, or JPL Richard did a decent modification to the vice, I’ll have to dig up.

#4

Thanks for the advice, what was the problem with the vise?

#5

Sorry, got sidetracked with work.
I mainly had a bit of slipping on the vice. Like I couldn’t clamp things down enough. Could’ve been operator error. Here’s the video of the upgrade @RichCournoyer did:

2 Likes
#6

I’ve done the majority of my machining in the C3D vise (and I basically only mill Aluminium) but as Josh said, it can slip. However in my experience, it only does that when you push the machine too hard or you’re not using the vise properly.

I think you’re being hit by the latter. I strongly recommend you do not elevate stock in the vise. This isn’t a machining vise like you’ll see on the bigger mills, which can exert literal tons of pressure to hold the stock in place and so work at any height. With the C3D vise, you want as much surface contact as you can get.

If you want full access to the sides, I’d second the recommendation for tape + superglue or some kind of low-profile clamp.

2 Likes
#7

The other option for full contact is to use soft jaws (Renshape is a usual choice, but expensive).

#8

What milling parameters are you using? Chipload? DOC? WOC?

I recommend you check out @Julien’s incredible ebook and look at the section on milling parameters there.

https://shapeokoenthusiasts.gitbook.io/shapeoko-cnc-a-to-z/

2 Likes
#9

I’d recommend the videos posted earlier to get a good starting point and build some confidence not breaking things, then come back to the book’s feeds and speeds section to understand things a bit better and learn how you can tune/challenge the machine.

3 Likes
#10

This is good advice to get the theory for these things, but I wouldn’t recommend taking any of the example numbers from the Shapeoko book and use them on a Nomad.

My recommendation for the Nomad is to tune the parameters with your ears.

#11

Great advice @Moded1952. Thanks for recommending other materials I neglected.

@Gerry - The Shapeoko starting points are still good reference points for the Nomad. Minimum chipload before rubbing basics still apply, regardless of what machine you use. Also, tuning with your ears is not helpful when first starting out. I couldn’t figure it out when I first started milling since I didn’t know what to listen for yet. Starting with known good parameters is helpful to figure out other issues like workholding, coolant, etc.

1 Like
#12

I was just suggesting you don’t take figures like this from the book and apply them to the Nomad. Though of course, if these work for you that’s great… my Nomad’s spindle won’t go above 10K, though:

snip

  • RPM in the 16k–20k range
  • Feedrate in the 30–60 ipm range (lower for hard wood, faster for soft wood)
  • Depth per pass in the 0.1–0.2’’ range
  • Plunge rate in the 10–20 ipm range

/snip

The tuning with the ears is probably not wise advice, I agree. It was more intended to reflect that if it is sounding really horrible, it’s probably wrong.

#13

Another consideration here is the torque of the spindle — for the first two Nomad models the recommendation was that larger tooling (1/4") only be used in softer materials — not sure if that is changed for the 3 or no.

Hopefully @wmoy can chime in on that.

#14

Right, I wasn’t suggestion to try and use those parameters. I was pulling from the chiploads recommended by Julien in the Shapeoko Chipload Guidelines section.

For the minimum chipload value to avoid rubbing, there is a large consensus in the CNC community that a value of 0.001’’ (0.0254mm) is a good absolute lower limit guideline, at least for 1/4’’ endmills and larger. It may need to be lowered to 0.0005’’ for 1/8’’ and smaller endmills.

I recommend he start with the minimum chipload, a light DOC (10% endmill diameter) and light WOC 10% endmill diameter), and see how that works.

3 Likes