Taking the CNC Plunge

[TomS]

One other thing I can think of. What alloy are you cutting on? I ran into some that was annealed (I think anyway) and it was gummy and didn't finish well at all.

6061-T6. BTW - was able to get in the shop this morning before I hit the road. Spindle taper runout was no more than .0002". I still need to take more readings with the spindle at operating temp.

Tom S.

 

[TomS]

A couple of thoughts;

Do you lock the quill when running?

On the spline, mine rattled a lot when I first did the CNC conversion. I solved that by pumping the space between the splines full of high pressure grease.

Yes, spindle is locked. I tried wheel bearing grease but that didn't help much. I'll see if I can find something that is a thicker consistency and give it another try.

I'm also going to check my gib adjustment. You never know.

Tom S.

 

[jbolt]

I used an amsoil product meant for heavy equipment chasis.

Sent from my SM-G955U using Tapatalk

 

[jbolt]

https://www.nexgencam.com/hsm-tips-tricks/item/understanding-cut-and-smoothing-tolerances

 

[TomS]

https://www.nexgencam.com/hsm-tips-tricks/item/understanding-cut-and-smoothing-tolerances

Interesting article. This certainly points to a possible cause, and solution. I use two CAM programs: CamBam and Fusion 360. Fusion has a smoothing setting and CamBam sort of has one. I ran my parts with CamBam. Hmmm? I'll run the program using Fusion and see what happens.

Tom S.

 

[TomS]

I created a test piece in Fusion and set up the CAM. The test piece is a 1/2" x 3" x 3" piece of aluminum with a 1.250" hole in the middle. I set the tolerance to .0004", checked smoothing and set the smoothing tolerance to .0004". Using a 3/8" 4 flute carbide end mill I pocketed the 1-1/4" hole at 4000 rpm and 10 IPM. Surface finish is still terrible.

Checked the spindle taper runout after running the spindle for 10 minutes. Still at no more than .0002".

I've got more reading to do on smoothing and Mach3. Evidently there are a few settings that can be turned on or off.

Tom S.

 

[Davd Flowers]

Try kicking the ipm to 25, at 10 ipm your not even taking a thou per tooth off....... I would be curious to see your g code to get a better idea what your doing. aonemarine at aol dot com.

 

[TomS]

Try kicking the ipm to 25, at 10 ipm your not even taking a thou per tooth off....... I would be curious to see your g code to get a better idea what your doing. aonemarine at aol dot com.

I started at 60 IPM, then 30, then 10. Not a significant change in surface finish with the three feed rates.

Here's the gcode file.

Edit: Been doing some reading on arc fitting. Haven't read enough yet but I'm thinking it's the same as smoothing.

 

[Davd Flowers]

Yikes!! Ok so your just slotting with no finish pass???

 

[Davd Flowers]

My mistake, I need to learn codeing better, i see the second pass for finishing...