Help with Prop Skin Inaccuracies with sketches

[ianhughes7UFVF]

Hi

I have been working on creating a set of R2D2 skins for the last week based on blueprints.

I have been creating sketches of the diameter of the skins and using that to create lines to create planes to create sketches to create panels on the surface of the skins.

But I have just started on a second sketch and certain parts need to line up but the resulting distance was a wrong measurement.

A friends comment on this was that I wasn't using : midpoint constraints and the chordal dimensions with point constraints.

I am not sure I totally undertand what he means

When I look at my sketch I have this arrangement:

To create a gap of say 0.5" I am creating a circle from a known point of 1" which the center will give me the second point to draw a line to.

When I zoom up on the sketch it looks like this:

I have the feeling that I am messing up all the connections and this is introducing inaccuracy. I doubt its just the graphics of my computer, but my lack of skills.

I have attached the file for you to look at and if you could tell me where I am going wrong that would be great. On the bottom sketch there is a measurement that is skew that has provoked my checking all this:

Instead of 0.556" it should be 5/8".

So a complete redo of the project once I work out how to do it right.

Any help would be great.

Regards

Ian

[laughingcreek]

Could you explain a little more what you are trying to achieve?

and could you show where the measurement that should be 5/8" is?

[ianhughes7UFVF]

Hi

This is the measurement that should be 5/8"

What this relates to is these two panels are meant to be in line with each other and they are as I used a front sketch to line them up, but the gap between the lower panel and the one to the right of it in the picture should be 5/8" whereas it is a lot less.

There are blueprints in relation to this so the issue may be more complicated than I am presenting.

I suppose what would be handy is for you to check my sketches 18 and 28 and see if my workings there are ok or completely messed up.

Regards

Ian

[laughingcreek]

honestly, I don't understand those sketches.  is this how the blue print is laid out?  did you get the dims from the blueprints? if so then I'm surprised you don't have more discrepancy's.  You can't ever count on blue prints to be 100% right.  

the top and bottom appear to be laid out by different methodologies,  I would have picked one and stuck to it.  again, surprised the top and bottom are as close as they are.

maybe if you posted a pic of the blue prints it would be easier to understand.

ps-looks like your "auto project geometry: is on in your preferences, which is why you get that ghosted profile anytime you create a sketch on a body.  I would turn that off, it's kind making a mess of your sketches.

[HughesTooling]

You are using projected points from sketch 18 in sketch 28. Both circles share the point in the rectangle but use different centrepoints. Don't know if you've snapped to the wrong point for the centre in sketch 28.

Mark

[ianhughes7UFVF]

Hi

Unfortunately I have posted a problem that requires alot more information to define my problems with the work.

I have 5 blueprints that do differ and I am getting direction from a chap on the variations on the figures.

Other than sharing all 5 blueprints here which I am not allowed to do, I carn't define more detail.

It sounds what I was doing isn't too off but there is a problem somewhere.

By the way, where do I look to turn off ghosting in preferences.

Regards

Ian

[davebYYPCU · Accepted solution]

As I understand it, not checked the file, so based on the info written, 

theres something wrong with the Body skin you showed us.

Has the other chap told you what is wrong, 1st thing you need,

and how do you know he is not mistaken?

it appears you are double checking measurements, point to point, where it may be that arc length is what you should be measuring.

Ghosting?  You can hide profile shading from the sketch pallet, turn it back on before Finish Sketch.

Might help....

[ianhughes7UFVF]

Hi

These are not going to totally help because they have certain measurements that the builders changed that the chap I am dealing with has ascertained.

As you will see, the designers have worked around the circumference and defined the lengths of panels some of the spaces inbetween panels is different to whats on here, and the first is a top section whilst the bottom is a lower section.

So what I have done is based my work on starting at the center and creating the measurement distances with the circles to create the lines between two points.

If there is a better way of doing this it would help.

I have just messaged the chap to check his measurements.

Regards

Ian

[davebYYPCU · Accepted solution]

If it is what you have got, then yes point to point measures are correct.

[ianhughes7UFVF]

Hi

So how I am creating the lines with circles is a good way to do it?

If so then the error is possibly in the measurement alternatives I am being given?

Regards

Ian

[davebYYPCU · Accepted solution]

Process of elimination, is the body diameter correct, then as you say, dimensioned construction circles, helps find the correct intersections.

Over the top of that, is the known alteration/s from these drawings, no good trying to find the error, if a modification eliminates that accuracy, checks must incorporate known design changes.

[ianhughes7UFVF]

Hi

I am waiting to hear from the chap about that specific measurement and I want him to provide me with annotated corrected blueprints.

Then we may find out how to improve on the work.

Regards

Ian

[Johnc911]

Could it be as simple as you’re measuring the radius of the small circles but you should be measuring along the circumference  of the larger circle? The latter would be slightly longer. 

[davebYYPCU]

I thought that too, but the pics show point to point.