Milling an undercut

[Thoob]

Hey guys, I have a part I need to undercut. Picture a pulley, thats the kind of undercut it is, however it isn't round so I cannot turn it on the lathe. The problem is I don't know how to put a rough cycle to it to take the material out radially. The "surface contour" I'm using wants to take a lot radially which I can't do cause 1, the tool can't handle it and 2, the part is not that rigid to accept such a large cut. What toolpath would I use to remove that material out? The tool is a slotmill 5.08" diameter and 5/8" diameter inserts. The part undercut is 17/32 full radius.

[Thoob]

I attached a picture for better visualization.

[?Mark]

Simple multipass contour and trim the toolpath to get rid of air-cutting...

 

Surface Rough contour if you have to surface it...you can trim it too.

 

hth

[Rotary Ninja]

I would do the same, use a 2d contour toolpath with multi-passes. Leave .005" to .010" on the walls. Cut to centerline of the tool and contour in Z. Then try your surfacing toolpaths. If flowline works with undercut tools (I've never tried it) I would use that. If not use surface finish contour with a very small stepdown.

[The Chipmaker]

You can cut that with a surface contour program using a radius slot mill. Play with your z cut depths and enrty. Maybe use gouge check. Make the top a drive surface and it shouldn't gouge it. With it as a check it may gouge. I do undercuts like that often. You can rough it using the contour mill too. The first cut is the one you have to worry about taking too much material, but play with it and you'll figure it out. Good luck!

[Thoob]

If I use a 2D toolpath with multipass, how will that get rid of most of the material? Its a 17/32 Radius and the cutter is only 5/16 radius. It would not take out near the top and bottom of the rad, only the middle. Not so familiar with these types of surface toolpaths. I'd say I'm a little green ion that area.

Thanks ChipMaker, I will try to make the edge a drive surface.

[Jayson Kramer]

Thoob what is the material I made a few just like that shape in the past.

I use a full radii key cutter and flowline.

[Chris Rizzo]

^ What Jay says above.

 

Another way with multi-passes and full rad keyseat cutter. Create several offset surfaces, driving each one with it's own toolpath

 

Create > surf > from solid

 

Create > surf > offset Do this however many mulitpasses you want

 

Toolpaths > Surf Fin Contour For the outermost surface. Once you get one toolpath looking good, just copy and re-select the successively closer surfaces.

 

With surf fin contour you've got really good control with lead in/out, which I like.

 

hth

[RayD]

If you have Multiaxis Morph between 2 curves works great for that shape, force it to 3 axis output. Gives you all kinds of roughing options if needed.

 

Otherwise all of the suggested paths work.

[Thoob]

Its just 44W plate, Mild Steel. I am testing different methods as you guys suggested. I will let you know how I do. I really appreciate the responses. Thank you.

Just one thing though, how do you control the lead in and out so it doesn't gouge the part with flowline?

[?Mark]

With flowline you don't have this control, just a simple direction before first cut and after the last cut. Only finish/rough contour surface toolpath gives you this option.

 

hth

[Thoob]

With flowline you don't have this control, just a simple direction before first cut and after the last cut. Only finish/rough contour surface toolpath gives you this option.

 

hth

 

 

Thoob what is the material I made a few just like that shape in the past.

I use a full radii key cutter and flowline.

 

^^^^How does he do it? lol

[Jayson Kramer]

you want me to show you?

[Rotary Ninja]

If I use a 2D toolpath with multipass, how will that get rid of most of the material? Its a 17/32 Radius and the cutter is only 5/16 radius. It would not take out near the top and bottom of the rad, only the middle. Not so familiar with these types of surface toolpaths. I'd say I'm a little green ion that area.

Thanks ChipMaker, I will try to make the edge a drive surface.

 

Because in your initial post you said...

 

 

The tool is a slotmill 5.08" diameter and 5/8" diameter inserts. The part undercut is 17/32 full radius.

[Thoob]

Ya re read it. Its the same. lol

5/8" diameter inserts = 5/16 radius. Part is 17/32 radius = 1-1/16 diameter

[Thoob]

you want me to show you?

 

I would like that. Thank you.

[Jayson Kramer]

can you send me your model?

[Thoob]

Sent you a PM

[Jayson Kramer]

Thoob you have mail.

[Rotary Ninja]

Ahh Thoob. I was mistaken. I see your problem then.

[Rotary Ninja]

I would probably still drive the center with a multi-pass. Then I would take a cut or two above and below center using the same method before going to a finish toolpath.

[Thoob]

I have Jay working with me on getting it right. I agree that the flowline toolpath works the best as the step down is small so the cutter being engaged that far is ok. Its that first initial cut that is the problem. I was thinking I might just drive that height with multiple passes until I have most of that area taken out, then finish with the flowline? Jay I replied to your email yesterday afternoon.

[Mjölnir]

I've finished parts like that with 2D swept tool paths. In some situations offsetting and translating the wire frame geometry to the center of the tool and writing zero tool diameter tool paths is the best option. Years ago in many instances it was the only option.

[Rotary Ninja]

You could offset the surface .035" or so, then create flowline curves on the new surfaces and drive those with a contour. Cut the top curve, then the bottom, back and forth working in to the center. Then go to the surface finish.

[Jayson Kramer]

Thoob, I will get more detail to you today. yesterday had meetings in the afternoon and customer to see. I have to go out today to a customer but I can reply when I get there. have to get ready now to go. I have a few hour drive.

Thoob you have a number I can call you at? if so email it to me.