machining draft with tapered cutters, feature sets?

[stdpattern]

I have a few jobs that are basically squares with pockets.  I have models with no draft, but draft is required.  I'm thinking of using tapered cutters, and I'm wondering if using features might make this easier.  I can add draft to the model if needed, but if I could leave it square, that kinda eliminates a step.  Any thoughts on machining pockets / bosses with draft using a tapered cutter?  

Thanks

Steve

[Pijetro]

That's the way to go..

We phased out tapered cutters thank goodness..

Just realize, that adding taper to the pockets does it uniformly..If you need pockets with varied draft within the pocket, you'll either need surfaces, or create separate Features with separate tapers, and edit the toolpath...

[stdpattern]

thanks for the reply.

Yeah, we don't use the tapered tools too much anymore, it's just that these parts are pretty simple, and It might actually be quicker.  The only issue is the inside corners since the tool has a variable diameter, I'll just have to confirm what I can get away with or pick those corners with a ball and then end mill.

My original thought was to not mess wit the model, which doesn't have draft, but on second thought, I think it's better to add draft to the part in powershape.

What advantages do you see to using features vs just using say 3d area clearance and maybe constant Z?  That might be a topic of it's own, I like the idea of feature machining, but it seems like an extra step of creating the features when I've already got a model of the part that I can just machine.

Steve

[Pijetro]

Personally...

I like having the surfaces, and machining to what the design calls for..

The main reason I feel going to Features (pockets), like your scenario, is if you don't have the solid modelling tools, or if the shop floor needs something quick and simple machined.Like an insert pocket, or perhaps cutting out and building up for weld..

It's nice to be able to have a tool like this to override the surfaces...

In my case, any model changes required, need to go back through the engineering department.

[Anonymous]

Use Curve profile with Draft?

See sample macro

[stdpattern]

Thanks guys, some good info.  Just reminds me that Powermill has several ways to make most cuts.

I usually have a powershape model, so most everything I do is plain old surface machining of the model, but I can see where features and curves could be useful.  I never noticed that you can apply a draft angle to curve machining.

Steve

[Anonymous]

I work in the pattern mold industry. We are always given a blanket draft allowance over the entire part of a degree or two in our molds to get items to mold easier. What we do in our shop is Draft all the easy items in the part model and the more technical drafting complex surfaces we actually let the Powermill software do the draft computing in the toolpath. We do this by lying to Powermill about the type of tool we are actually cutting the mold with. We tell Powermill we are cutting with a drafted ball cutter. But in reality we are have a strait cutter in the CNC. Powermill keeps moving the cutter away from areas/features where it thinks the drafted cutter would violate giving you free draft in areas where modeling would be time consuming and complex thus saving you time. But take into consideration you only get the draft in mold pull direction you are cutting in.

Hope this is a help to some

Matt    

[stdpattern]

Interesting method, Matt.  We are a pattern shop, and only cut 3 axis, so I see what you are saying.  I've never thought of cutting with a ball but programming with a tapered ball.  I model nearly everything in Powershape with draft, so this rarely comes up.  Just happened to be  a couple quotes we were doing last week that had models provided without draft so I was thinking of this as an option.

I'll probably end up modeling the draft, but it is a good exercise to look at other methods.

Thanks

Steve

[Anonymous]

The only thing you have to watch out for is your fillet you will leave at the bottom of what ever you are cutting. the radius of the tool you cut with must match the your fillet note print requirement's. Also when creating your tapered tool you really have to manipulate the numbers to get your tool radius to match your draft and you often end up with a very long cutter.

Matt