Drill Helix

[indesign]

Drill Helix

I design tooling for many companies and was hoping this would be easy to do in Alibre.

I need to model a helical step drill (something I must do often). I can not find a good way to helical cut the flutes.

Flute geometry is defined from the tip (end of the tool) but the reference line to do a helical cut would run down the axis of the tool. ...2 different planes. And for actual manfacturing the wheel to grind would be at an angle to the axis of the tool but the helical cut would still need to be down the tool axis.

In either case the profile and the axis are in different planes. Can this be done in Alibre since the helical tools seem to require the sketch and the reference line be on the same 2D sketch. I have played around with several ways to draw the profile at the tool axis but do not come up with a good tool geometry. I guess it should be possible if I made a very detailed spline but in a 3 flute or more tool this gets difficult.

It would be easy if I could draw the profile from the end veiw (X,Y plane)and then select the reference line from the Z axis. But this is not possible. How hard could this be for this to be allowed?

 

[jemmej]

I ran into the same problem (though for a far more simple task). Trying to create a twisted pair of cables, you'd want your cross-section of your wire to be your profile and again, the helical path axis is normal to the cross-section. As far as I know, only creating a 3D spline and sweeping the cross-section creates this directly. As it stands, I cheated and rotated my profile and then chopped the ends off to get them normal to the axis! Don't think this would work in your application

Jim

 

[marc]

Helix

I had to create a helical screw model and export it into Algor. I simply created the tube, drew on a flight and used the extrude helix option. The part looked ok, but Algor did not see it well.

I was able to create the helix by using the outside dimensions and extruding a helical cut. This worked like a champ.

See it at http://www.meadowsanalysis.com/Client%2 ... /1646a.htm

Marc A. Meadows, P.E.
Fort Worth, Texas

 

[indesign]

Marc,

Yours works normal in Alibre like a thread. Mine does not and I found someone else with same problem over a helical gear. The tooth profile is drawn from the end (90 degrees from the part centerline) not the side of the form. We need to be able to extrude around a line, or axis, not in the sketch plane.

It does not seem to be too hard of a task to ask but I wonder who we could discuss this with other than tech. I need a developer to tell this to.

 

[MilesH]

Tim,

Isn't the flute profile defined 'normal' to the helical path? That must be the profile of the grinding wheel to make it? I'm curious...

Miles

 

[jemmej]

indesign,

If you file an enhancement request, the developers will see it.

Jim

 

[MilesH]

Re:

I ran into the same problem (though for a far more simple task). Trying to create a twisted pair of cables, you'd want your cross-section of your wire to be your profile and again, the helical path axis is normal to the cross-section. As far as I know, only creating a 3D spline and sweeping the cross-section creates this directly. As it stands, I cheated and rotated my profile and then chopped the ends off to get them normal to the axis! Don't think this would work in your application

Jim

Jim,

Unless I misunderstand, surely, setting 'profile orientation' to 'normal' will achieve what you wanted here?

Miles

 

[jemmej]

That's what I thought too, but it does not seem to work that way. At least, I could not get it to work.

To clarify, I could not select a reference line that was not part of my sketch. To be part of a sketch, both the cross-section and the axis have to be in the same plane.

Jim

 

[MilesH]

Jim,

It might not be ideal, but this is the way it works if you select 'normal'(Advanced tab):

Draw the profile as if it were 'normal' to the helical path but draw it in the same sketch/plane as the axis. The software will rotate the profile 'normal' to the helical path to create the helical feature. Hope this makes sense...

Miles

 

[indesign]

It does not work with any of the options suggested so I will post as an enhancement request.

Thanks

 

[indesign]

Re:

Tim,

Isn't the flute profile defined 'normal' to the helical path? That must be the profile of the grinding wheel to make it? I'm curious...

Miles

Flute profile is defined from end of tool. The geometry for the wheel used is defined at an angle to the axis based on a complex set of equations that I would hate to get started on. I worked with a software developer for years on a CNC Jungner grinder (Swedish machine) as tech support in the US. Believe me when I say it is complex. There are special programs developed just to calculate the wheel forms for step tools.

As a matter of fact the desired form for a tapered helical tool changes as it goes down the axis. So even if I have the fix the way I want it this would only resolve the issue of drawing for helixes that do not change diameter down the length. But I would still like the option for drawing the flute even if it is not geometricaly correct.

 

[MilesH]

Re:

Flute profile is defined from end of tool. The geometry for the wheel used is defined at an angle to the axis based on a complex set of equations that I would hate to get started on. I worked with a software developer for years on a CNC Jungner grinder (Swedish machine) as tech support in the US. Believe me when I say it is complex. There are special programs developed just to calculate the wheel forms for step tools.

As a matter of fact the desired form for a tapered helical tool changes as it goes down the axis. So even if I have the fix the way I want it this would only resolve the issue of drawing for helixes that do not change diameter down the length. But I would still like the option for drawing the flute even if it is not geometricaly correct.

Thanks, I don't need any more detail

I second your enhancement request and will file likewise.

Miles

 

[jemmej]

I have tried that Miles. Perhaps it IS doing it (a spherical cross-section may not be the best test case!). I'll try again and report back a little later.

Jim

 

[indesign]

I have made this work somewhat but the geometry isnt quite correct. Since it will do the profile normal to the helix I get a close form of what I wanted. This is good for visual and will help in my 2D drawings.

I would just like to be able to do this correct and not just an approximate guess. Of course the other problem is the back of the flute does not want to form with the radius I would normally need but that is more visual anyway. Any more to the feature request and I would be asking for a fluting simulator.

As far as a wire goes the normal option should work correctly due to it is the correct form normal to the helix. Don't worry that it does not allow you to select the axis you want but it does work. With my situation I can draw this drill but the flute goemetry is slightly scewed by the helix angle. Therefore the same shape at different helixes will give a different form when looking at the cut-away of the flute geometry.

 

[MilesH]

Couldn't you extrude the defined geometry up to a plane set at the helix angle. This would give you the required helix-normal geometry which you could project to a sketch. Copy this sketch onto the plane parallel to the axis so that it gets oriented correctly by AD for the 'normal' helical boss. A bit Byzantine, but....

Miles

 

[indesign]

I see what you are saying.....almost got by me. This I believe would give me the geometry at the helix angle for my helical cut anyway. Yes it is a long way around but I think it would give me the correct form (at least I hope so).

I will try that as needed but I still would like the option in the program to make life much easier.

Thanks for the input Miles. I couldn't see the forest for the trees.