vertical lead in radius when plunging into a cut

[Janger]

I'm milling out a the outside contour for a big bracket clamp. It is about 4" across. 0.05" plunge depth per trip around the outside of the part. The plunge is defaulted to be a ramp but with only a 0.04 radius. It goes THUNK into the cut. See the green preview in the simulation screen shot - the tool enters on the left sliding in and down from the very left. I'm thinking that I could change the radius to 0.25" and maybe it would be a lot smoother. I wonder if I'm damaging the EM doing this? Why does fusion default to 1/10 of the cutter diameter for the lead ins? wouldn't more generally be preferred? Oh and it's 15" per min and 5000 rpm. 12mm EM. Aluminium.

 

[Janger]

Picture of progress.

 

[jcdammeyer]

I saw a similar thing with the generated code for the pocket hole I was milling. Lots of options for ramping in.
I'm using the "Path" with those parameters.
I think it's important to look at the generated G-Code just like looking at the compiled assembler from C. Amazing how just a bit of rearranging can create quite different code.

 

[Janger]

Interesting John. So many different ways to approach this.

 

[Tom O]

Wouldn’t changing the lead in sweep angle relive some of the initial cutting pressure?

 

[Janger]

Well I just let it run. The cutter seems fine despite all the thunks into the part. I have worn off the coating on the EM already.

 

[Tom O]

It is a nice looking piece

 

[PeterT]

I'm more curious about what you're making unless its a Secret Squirrel project - an open gap slot on left side with a tightening bolt and a closed off gap on the right side.....also with a tightening bolt

 

[Janger]

It's a bicycle trailer adapter for a client. His seat tube is 60mm in diameter as it holds the e-bike battery. The trailer arm will attach to the pink tube.

 

[jcdammeyer]

Well I just let it run. The cutter seems fine despite all the thunks into the part. I have worn off the coating on the EM already.

This is a perfect example of why CAD/CAM and CNC can make things you can't easily do any other way. Although 3D printed pattern and lost wax along with boring the pipe clamp section perfectly round...

What did the raw billet for that cost?

 

[Janger]

I have a big hunk (3'x4' x 1") of aluminium left over from a water jet shop - it has a bunch of irregular shaped but salvageable sections. So it was not retail pricing on that material! I think the whole drop was $40. I wonder what metal mart would charge for that. plenty I'm sure. maybe I'll look. Well it's about 4 pounds of aluminium and last time I bought some it was $7 a pound. So it'd be at least $30 at metal super market, probably a lot more.

 

[Janger]

This is the drop plate I’m talking about. To use it I have to make multiple cuts with the jig saw and then the band saw.

 

[jcdammeyer]

This is the drop plate I’m talking about. To use it I have to make multiple cuts with the jig saw and then the band saw.
View attachment 36738

and then all the left over bits can go into the crucible...

 

[Janger]

I'm going to have to get started on casting... all the cool kids are casting.

 

[Alexander]

Definitely try plunging outside the part if you can. Seems possible here. But if your work holding gets in the way, go for a 2-degree ramp angle. Ramp down along the path, not radius down. It'll be easier on your end mill.

 

[PeterT]

This is the drop plate I’m talking about.

I see a lot of model engine parts hiding in there

 

[Janger]

Definitely try plunging outside the part if you can. Seems possible here. But if your work holding gets in the way, go for a 2-degree ramp angle. Ramp down along the path, not radius down. It'll be easier on your end mill.

I didn't think of plunging outside the part. Thanks Alex that's good advice.

 

[Janger]

It could use some paint...

 

[jcdammeyer]

It could use some paint...
View attachment 36753

Racing stripes...

 

[PeterT]

You might consider these curved standoffs or spacer washers (whatever they are called). A flat bolt on a curved tube is a tangent contact so not great for retention. On bike frames & similar accessories they are often brazed on permanent. But I've also seen them loose assembly like my Honda mower handles. If one is gronking the bolts to withstand trail rides, its better to have a solid or thicker core inside the tubing because its easy to deform in that squeeze orientation.