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Rounf extrusion

43 REPLIES 43
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Message 1 of 44
leech10
1618 Views, 43 Replies

Rounf extrusion

Hi



Thanks for your help. I have done my piston apart one thing. I attached 3 pictures. I dont know how to do cut like in the tutorial. I tried to do circle in cut view mode. (I attached a picture) but I dont know how to go round with it. Moreover when I click finish sketch the second part of the piston appears and I dont see cut of my model. When I am creating sketch in this mode I cannot see anything highlighted on the piston cut when I move the cursor on so It is also difficult to determine where the center of the piston part is.



Regards

Piotr



P.S. Is it difficult to animate reciprocating engine, only one piston and valves, I wanna prepare presentation

43 REPLIES 43
Message 2 of 44
JDMather
in reply to: leech10

The turorial shows a Revolve - Cut, not an extrude.
Also - it appears your sketch isn't constrained like it is in the tutorial image.

I recommend you start here http://home.pct.edu/~jmather/SkillsUSA%20University.pdf

 

Animation is simple, but it looks like you are a long way from being ready for animation.

Attach each one of your part files here as you complete them.


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Message 3 of 44
leech10
in reply to: leech10

Hi

 

All of the parts, except camshaft( I saw that there is generator in iam mode, so I have not created it in the part mode) are attached. I know there is for sure constrain issue in cylinder as I had a problem with extrude command. I found Project geometry function which shows this piston better, when it is cut. I saw animation with blue intake air and red combustion/exhaust air comming thru valves. I thought about such an animation. 

 

Please check if those parts are correct for this. Then I will try to assemble them. I dont know if I have to make some gears and cambelt to have proper valves opening times or if there is another posibility to telll the iventor about crankshaft-camshaft revolution ratio.  

 

Regards

Peter

Message 4 of 44
leech10
in reply to: leech10

I made also assembly, but I have a problems with setting appropriate degrees of freedom. i.e. setting piston moving up/down in cylinder or crankrod attached correctly to crank

Message 5 of 44
JDMather
in reply to: leech10

Everything you have done is not done correctly - close, but not correct.

Are you interested in learning how to do this stuff correctly (I can get you started on one part and then I think you will be able to quickly figure out how to fix the others).


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Message 6 of 44
leech10
in reply to: leech10

Hi

 

Yes I am very interested. I hope that I have done at least one thing correctly:-( 

 

How would you like me to show how to do this?

 

So that means I dont have to draw it from the beginning but just correct those ones I have done? Or I have to draw it from the beginning( I will do if neccessary, good to know how to draw correctly from the beginning and how to fix wrong ones)

 

Regards

Piotr

Message 7 of 44
JDMather
in reply to: leech10

I recommend that you start by reading this document

http://home.pct.edu/~jmather/SkillsUSA%20University.pdf

 

then open your Valve.ipt and edit Sketch1.

Notice in the lower right corner of the screen that Inventor indicates that you would need 26 missing dimensions to manufacture this part.

 

Notice that you are missing a bunch of Horizontal and Vertical Constraints.

For example, notice that the 12.5 line is not constrained horizontally (if you don't see your constraints - click the right mouse button and select Show All Constraints).

In fact there is only one vertical constraint.

I don't really understand how you are doing this as Inventor should automatically be creating those constraints.

 

Notice that there is more than one vertical line (see red circle) where there should be only on vertical line from bottom to top of the part.

 Valve.PNG

 

 

I recommend you start the part over from scratch in a new file to compare the new technique you will learn to how you originally did the part.

 

 

Sketch one horizontal line from the origin to the right and dimension it 12.5

Did you notice anything when you  dimensioned (line should change color).

Show All Constraints - Inventor should have automatically added a horizontal constraints - no extra work for you, in fact, you are already doing lot of extra work.  We are going to get lazy and do less work.

Notice in lower right corner of screen that it says Fully Constrained.

 

Draw 1 vertical line from origin and dimension for height of the part.
Go back to your original and add this missing dimension.

Notice anything different?

 

Attach the new file here for further instruction.


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Message 8 of 44
leech10
in reply to: JDMather

Hi

 

I found 1st issue. I had auto constrain function turned off. I read about it in your article. But Even if I draw just simple line it does say 2 dimensions needed. Constrain is added automatically but which dimensions are needed?  Sketch doctor says that everything is fine, but sketch is not constrained

 

Regards

Message 9 of 44
Anonymous
in reply to: leech10

Did you project the center point from the origin folder and constrain some point in your sketch to it?

If so try putting a horizontal constraint on the bottom line and see what happens.

 

Message 10 of 44
JDMather
in reply to: leech10

See Tip #6 (this should be default).

http://home.pct.edu/~jmather/SkillsUSA%20University.pdf

your origin is not automatically projected.

 

Now sketch one horizontal line from the (projected) origin to the right.

Dimension it and attach the file here. (don't create anything else, once we fix the problem for this one line - everything else should fall in place)

your origin is not automatically projected.

 

Now sketch one horizontal line from the (projected) origin to the right.

Dimension it and attach the file here.  (don't create anything else, once we fix the problem for this one line - everything else should fall in place)


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Message 11 of 44
leech10
in reply to: JDMather

Hi

 

 

Now looks better. 

Message 12 of 44
leech10
in reply to: leech10

Thnak you very much. I found what I was doing wrong. I did my valve now it is fully constrained. I know it was very simple and stupid, but I got it I have not noticed that I have to constrain this point on the splineSmiley Sad. I will try to fix the rest of my parts now. If I need help( and for sure I need) I will ask more. 

 

Regards

 

Message 13 of 44
JDMather
in reply to: leech10

Another little tip - if you change this line to center line (upper right corner of screen) you can avoid calculations.

I always try to avoid calculations if the geometry will solve the problem.

 

Center line.png

 

I'm also going to nit-pick clearances between cylindrical shafts and the holes they are supposed to go into.

There must be clearance in the real world for the parts to move - might as well design them that way.


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Message 14 of 44
leech10
in reply to: JDMather

Could you please check this part. I drawn it once more 

Message 15 of 44
Anonymous
in reply to: leech10

See attached for some ideas.

Message 16 of 44
leech10
in reply to: Anonymous

Thanks for help. Without it I would not finish it.

 

I will ask you about assembly after I finish parts tommorow. now I know how to do this. 

 

Regards

Message 17 of 44
leech10
in reply to: leech10

Hi

 

I am lost with dimensions again. I attached file where 2 dimansions are still needed but I dont know how to find them. I tried many but without success. Is there any easy way to determine which are missing

 

Also the one in the picture. 1 dimension is missing, but which one? I tried tangent constrain so it alligned inner circle to outer one but it is still missing constrain.

 

I have made it fully constrained but I had to add one vertical line, not only dimension. For me it looks strange but if it must be done this way I will leave it

 

 

regards

 

Message 18 of 44
Anonymous
in reply to: leech10

See attached.

Do you really need to use splines?  Much simpler to us multiple radii.

Project the axis and use mirror constraints to make both sides the same.

Do this at the start of the sketch, It will be much easier to constrain.

Start with your functional elements, the diameter at the top and the radius at the bottom and get them constrained first.

Then build the outside around that.

Message 19 of 44
leech10
in reply to: Anonymous

Hi

 

Finally I made sth like this. I put it into assembly, enabled contact set and constrained it. I dont know how to set the cylinder verticaly to ground,  and how to move the crank to move piston up and down. How do you set for example having rod placed exacly in the middle od the crank. Aso I dont know how to set crank to do rotating movement, not moving from left to right and up and down. 

 

 

 

regards

 

Message 20 of 44
JDMather
in reply to: leech10

I will try to show you how to do the assembly tomorrow if someone else doesn't jump in here.

 

I know you are following a tutorial, but I thought you might want to see an easier technique to model one of your parts.

Closely examine the sketch part and the solid part files attached.


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