Diamter changes over a curve

[a3_bham]

I have similar hole extrusion which has 1degree draft applied, group them together. When you pattern these using the fill command and the extruded hole with the draft applied goes over a sloped/curved surface the diamter changes. Is there an option within the draft or another feature to make it constant no matter what surface is comes across. Or any think to help me on this issue?

 

[tommypurple2]

I would rethink the idea of patterning drafted features.


You should pattern your holes and then draft them.

 

[a3_bham]

I have done that i.e created one hole patterned it, thats fine I can check the diameter and there all the same, I added some on one of the holes and it fine, but when I pattern the draft it becomes in correct as its over a a curved extrusion. i.e. there most be a option to keep the draft constant in a line of draw.

 

[kirancitd]

Check the draft hinge. Try to mantain the draft hinge same for all

 

[a3_bham]

Is that an option? Because all I can select id the edge for the hindge, when patterned it falls over any ways round this?

 

[kirancitd]

can you post some pics

 

[a3_bham]

How do I post images as this is my first time using MCAD

 

[kirancitd]

 

[a3_bham]

The image above shows that the top hole is alot smaller than the bottom hole. Yet they have been produce by the same pattern and with the same amount of draft, yet there different because it follows round a curve, which can be seen below.




It can also be send from the image above that the hole on the right is smaller than the hole on the left.

 

[a3_bham]

I've uploaded the file if you find it hard to understand

 

[a3_bham]

Sorry but the file didnt upload,

Link below



2008-07-23_074848_prt0001.prt.rar

 

[kirancitd]

2008-07-23_083445_prt0001.prt.zip


Please go thru the part file


i am unable to doenload your part
Edited by: kirancitd

 

[a3_bham]

Hi Thanks for the part, that is exactly what im getting, If you measure the diameter of the holes, they read the following: -

5.045
5.004
5.164
5.574

What im trying to achieve is that there all the same even though they go round a curve

I think it is because we have used a datumn for the draft were we need to use the surface, but im unable to achieve this.

 

[abrazors]

Create a datum curve using the Intersect command with the surface of the part and the hole surface. Then use that curve as the hinge for your draft.
Edited by: abrazors

 

[a3_bham]

Ni Have you tried this, as I still cant get the draft to work

 

[kdem]

Looking at the pictures and trying recreate what you are trying I don't think you are going to get what you want. Althoughthe hole diameters are the same the geometry of the holes is not. From the second picture, the draft surfaces of the hole circled on the leftare longer than the draft surfaces of the hole circled on the right. Because of this you will get different geometry from one hole to the next.One reasonpatterningthe draftsmay not workis that the curve used for the draft hinge (edge of hole) changes from one hole to the next. Another reason if you are using a plane as the draft hinge may be that the draft angle works on some of the hole instances but causes a failure on others.

 

[kirancitd]

can you tell how you are measuring the diameter

 

[dewme5]

I can think of two ways. The first, create seven datum planes, one for each row of holes, = seven drafts. As the rows become shallower, the pre-draft holes will need to increase in size to compensate. This can maintain a set angle for the draft.

The other method, is to incorporate the draft into the initial modeling, and not leaving it for a separate operation afterwords. Your longest hole will determine minimum draft angle. The shorter holes will result in larger angles of draft, but the look will remain the same.

This is not going to be a one-click solution no matter which method you choose. As far as I know, they will have to be treated as seven separate groups of holes, not one large group.