[altair]

Hi everyone,
I would like to ask the experienced ones here if the following machining strategy is possible, either in Sprutcam, Visualmill, or other software.

I would like to machine a propeller blade with the SIDE of the end mill instead of the tip as is common.

What I envision is this:
The blade blank is retained by a chuck in the A axis, meaning that it will be able to rotate during machining (as if changing pitch), to give access to the front and back of the blade. So the blade is horizontal on the milling machine.

The end mill is in the spindle as usual, but the Z axis is fixed in place and does not move vertically. The end mill is long enough to span the entire chord of the blade.

The X axis will run the whole length of the blade, and the Y axis will take charge of the changing thickness of the blade.

I cannot find a way to program this in CAM. So I wonder if it is at all possible to do this kind of work.

Do any of you have seen this done before?

Thanks in advance !

[TXFred]

I think that Sprut can accomplish this.

You need to use the Rotary Machining toolpath.
On the Strategy page, set the Trajectory Form to Linear.
Under Contact Tool Type you can select To Axis, which lets you shift the end mill to one side.

You'll need to play around with the Offset and Side Angle numbers.

I haven't tried it myself, but it looks promising.

Frederic

[altair]

Thanks Frederic,

I'm happy to see that it would be possible.
I do not have Sprutcam yet, I am running with Visualmill, but I plan on upgrading soon, so if Sprutcam can do that, that would be great.

Has anybody already got experience with this machining strategy?

Cheers,

Altair

[Geof]

I cannot comment on the CAM side of things but do have some thoughts about your machining strategy.

You are likely to run into problems with chatter. Presumably your blade is going to be thin compared with its length and you do not mention having a 'tailstock' supporting the end of the blade. Furthermore you plan on using the side of the cutter so you are going to have a lot of the cutter engaged in the cut.

Without a tailstock supporting the far end of the blade you are likely to get serious deflection and chatter as the cutter moves away from the chuck on the rotary and approaches the unsupported end of the blade.

With a tailstock you will get less deflection but there is a good possibility you will get chatter near the mid section of the blade.

Before spending a lot of time figuring out how to program a proper blade profile using CAM it might be worthwhile to wirte some simple code that will generate a tapered helix and machine a sample just to find out how much chatter you do get.

[TXFred]

I got bored and fired up Sprut to try this out. It does not appear to work the way I thought it could. 20 minutes of testing didn't get a good result.

Frederic

[altair]

Thanks Geof, for the reply.
You're right, I didn't mention everything. I was indeed planning to have the other end of the blade held in a tailstock, otherwise it wouldn't be workable.

And instead of a standard end mill, I was thinking about using a Shelix helical cutterhead with both ends on bearings.
SHELIX JOURNALS
SHELIX

This type of cutter does a fantastic job in wood, and I believe that it would produce a lot less vibration than a standard end mill while cutting the blade. A 2½" cutter turning at 6000 RPM should be quite smooth.

Now if this can not be programmed as I was planning, the whole project will have to be scrapped Fred did not get good results in his investigation.

[altair]

I'd like to ask everyone, what affordable CAM program do you think would be able to do this kind of machining strategy ?

Alternatively, where would you recommend me to go to ask for advise on this?
I do not want to clutter the forum needlessly by posting the same questions over & over.

Thanks guys !

altair