Constraint on points, how to get points, axis

[linnmaster]

Hello.
I've attached a file of a circular flange that is used to bolt an access hatch to a cylindrical water tank on the curved face. It is a circular ring in flat.
When it's rolled (like it is), to a curvature, there is nothing that is round or cicular. I need to build an assembly with nuts welded to where the holes are to allow bolts to bolt the hatch door to. How do I constrain nuts to the holes? I thought the easiest way is to create some sort of constraint is a work point in the "center" of the holes, but these holes aren't round. I would also then need a work axis through each hole, which requires another work point (one on one side of the hole, another on the other side) so I can insert with the bolt. How can you get these work points?
Any other method?
Thanks for your help.
Regards, David.

[linnmaster]

Unfortunately (and I just realised this), the development is NOT circular in flat ... I'm not quite sure why, but it's not ...
I'll have to work on this, but my constraint problem still remains nonetheless.

[shift1313]

I cant open the file up here at work but are your nuts going to be planar to the flange your bolting to or are they going to just lay on the face? You could create a 2d sketch with location points and project it onto your part. ill try to open it up at home.

[JD Mather]

Unfortunately (and I just realised this), the development is NOT circular in flat ... I'm not quite sure why, but it's not ...
I'll have to work on this, but my constraint problem still remains nonetheless.

I don't think you want this to be circular in the flat. Although that is often the way the ring will be made because it is cheaper (at least with older manuf processes) allowance would have to be made as it isn't circular when bent.

So the question is how will it be cut when flat - Computer controlled waterjet, plasma or laser (shape will be slightly elliptical in flat - but no problem for the computer) or circular rotating table or tool cut?

If I get time maybe I'll just post either method. I assume the holes will be drilled in the ring while flat. (or will they be cut as above)

In any case I would do one hole and pattern the feature rather than sketch as the patterned feature can be used to automate the placement of the fasteners (pick the pattern and done).

[linnmaster]

I cant open the file up here at work but are your nuts going to be planar to the flange your bolting to or are they going to just lay on the face? You could create a 2d sketch with location points and project it onto your part. ill try to open it up at home.

Correct, just lay on the face and welded fully around. Can't do 2D sketch as it's rolled ...

[linnmaster]

I don't think you want this to be circular in the flat. Although that is often the way the ring will be made because it is cheaper (at least with older manuf processes) allowance would have to be made as it isn't circular when bent.

So the question is how will it be cut when flat - Computer controlled waterjet, plasma or laser (shape will be slightly elliptical in flat - but no problem for the computer) or circular rotating table or tool cut?

If I get time maybe I'll just post either method. I assume the holes will be drilled in the ring while flat. (or will they be cut as above)

In any case I would do one hole and pattern the feature rather than sketch as the patterned feature can be used to automate the placement of the fasteners (pick the pattern and done).

Hi. It will be cut circular when flat. The ring, and all the holes - all circular, all cut in flat. When it's rolled, it's result is what it is when rolled from flat. Reason for wanting cicular is there is a direct G-code function for "circle", rather than a series of x and y movements for an ellipse, hence it makes the program much more simple and able to be modified easily by the laser operator in the odd occasion if I make a stuff up Maybe modern software may have a G-code function for ellipse, but our laser and CAM software does not allow.

[shift1313]

Correct, just lay on the face and welded fully around. Can't do 2D sketch as it's rolled ...

i understand that its rolled but you can do a 2d sketch off the face and project the points. See attached image. I created a curved face, a 2d sketch with an array of points and projected them to the face.

[linnmaster]

i understand that its rolled but you can do a 2d sketch off the face and project the points. See attached image. I created a curved face, a 2d sketch with an array of points and projected them to the face.

Hmmm ... interesting idea ... let me have a play with that in the meantime ...

[shift1313]

i opened your file up and i dont think that will work out in this case. What i did was create(in your part file) some work axis'. and then i created a plane that was tangent to the surface at a hole in question. You can add two mate to center points of a nut on the axis then constrain the face of the nut to the work plane at that hole. Its a lot of work.

Do you need these in the model for some reason or is this just an exercise. I know you need the part.

[linnmaster]

i opened your file up and i dont think that will work out in this case. What i did was create(in your part file) some work axis'. and then i created a plane that was tangent to the surface at a hole in question. You can add two mate to center points of a nut on the axis then constrain the face of the nut to the work plane at that hole. Its a lot of work.

Do you need these in the model for some reason or is this just an exercise. I know you need the part.

Hmmm ... not sure what you're meaning exactly with the creation of "some work axis" ... what are you using to make this work axis? If I can get a work axis through a hole, then I think I'll be home. Actually, it will work with just work points on the hole "centers" ... cos then I can tangent mate the face of the nut to the curve of the flange ...

Well, the assembly drawing needs to detail that each nut is there as shown and welded fully around with 6mm fillet weld. I know this, but we want to explore the option of getting these components made and assembled elsewhere, hence the need for the details inthe drawings to be precise and clear ...