Propeller Fin

[Reko]

Hi,

 

I have a big cast steel propeller to machine and I was hoping for some 3D programming tips on machining it.

 

It looks just like the prop on a boat... except it is 110" in diameter.

 

There is only about 1/2" of stock on the fins (both sides) and I have a solid model, so really all I need to do is come up with some good strategies to make a rough pass and a finish pass with a ball EM.

 

I was thinking a finish blend path to finish it... but I would like some opinions from some of the guru's here on both roughing and finishing.

 

Thank you, in advance.

[Reko]

Actually, the finish blend path looks like a bad idea... too irregular of a surface/surfaces... the basic finish scallop looks like the cleanest finish so far.

 

I might have a go at the HS Finish paths next.

[Tyler Robertson]

you might like the hybrid path, but the HS Scallop should do a good job

[Trevor Bailey]

will depend on how big the blades are and if they need to be held together for front and back machining. done a few of these in the past, 3 and 4 blades, hubs 5"-10" diameter with blade lengths ranging from 5" to 15" long. workholding is the key here.

[Reko]

Thanks Ty. Yes... I tried the HS Hybrid and it looks great (on screen) so I think I'll go with that. Now, on to the roughing. I'm going to make an STL file with 3/4" of stock on it and use Rest Rough/Cad File.

 

Trevor. Yes. This thing is big.... 110" diameter with 30" long blades. We are going to weld pads on the outside diameter and clamp on them, then, turn the diameter last.

 

I'm looking forward to this project. I'll try to post pic's when it is done.

[Reko]

Does anyone think it is possible to machine these propeller fins using a 90 degree head with a slotting cutter attached?

[Trevor Bailey]

you are already going to be fighting vibration issues. using an agg will mean you will have to go much slower. just my opinion.

[K2csq7]

+1 agg = last resort, rigidity issues galore.

[Reko]

Okay. Yes. That is a good point.

[Aaron Eberhard]

I'd probably go with a HS Finish pass as well, so you can control the tool engagement completely. As you already know, vibration will kill you, so one thing to be careful of is that you don't leave too little stock for your finish pass. You need to walk the line between leaving a small enough amount for finishing that you get a good surface, but enough material that it's not bouncing the cutter.. In addition to the tabs you weld at the end, I'd put some sort of adjustable pegs underneath when it's fixtured up to help put a little load on it (assuming it's being machined one side at a time in a 3 axis mill, nothing to the contrary was said).

 

Sounds like fun

[Reko]

Yes. 3 Axis Gantry mill. I can get to within 8" of the center hub, and then I will have to put some tooling balls in the pads I have welded on it. Then I can put my 90 degree head on and do each fin individually for the final 8".

 

We were supposed to have our 5 axis Gantry finished and ready to run when we quoted this job. THAT would have been sweet to do this job there, but it is taking a bit longer than anticipated.

 

We'll have to make do until then.

 

Thanks for the advice.