removing material from both sides

[jrl5735]

I'll start by saying I do not use Inventor except to convert my iges file to an stp file for cnc use. That being said my guess is all of you understand extrude, subtract, union commands.

My end product is supposed to be a roughly 5'x4' rectangular piece with a hole in it. Think of the piece as a floor with a slope on both sides of the piece, sloping down toward the hole 1 degree. The hole is not centered. My ending thickness at the hole can be no less than 1/8" and on the perimeter no more than 3/4". You'll notice in the Final Shower Pan.dwg I've provided that the slope runs flat at the very outside edge on the right side because my hole isn't centered. Yes, the hole needs to be where it is.

I had a test piece made at 1/4" scale where the cnc machine took out 1/8" of material. That being said my guess is my profile thickness at the hole has to account for that 1/8" of material being removed because that equates to 1/4" for both sides. So I should tell my cnc guy to remove 1/32 or make my profile thicker before I revolve it.

I can get this to work fine on one side as seen in the Final Shower Pan.dwg

or

I can create a profile and revolve that around a circle without the 4x5 piece.

Here's what I've done...

Draw a 5x4 closed polyline with a 4.25" hole, not centered.

Extrude both to a height of 3/4"

Subtract the hole.

Draw a center line vertically through the piece and the center of the hole to revolve a profile around.

Revolve the profile around the center line 360.

Subtract the revolved result from the extruded rectangle.

• If I do this last part with a profile that reflects my 1 degree slope top and bottom, the subtraction occurs in the middle of the piece or through the thickness of the material. Leaving the top and bottom flat and hollowing out the center.

I can however just throw the extruded rectangle and hole away and just extrude my profile and all is right with the world. I'm sure I'm just doing steps wrong or some such.

J. Logan

[SBix26 · Accepted solution]

Can you draw or sketch a section through the hole showing the slope on each side and the thickness at the edges and at the hole?  Something doesn't add up here, if you want piece to be symmetrical.  Your Final Shower Pan.dwg is very simple to reproduce, but your hole is not located in the middle of the part thickness (3/4") but all the way at one side.  If you move it to the middle of the part thickness, then the 1° slope means that it doesn't go anywhere near the edge of the rectangle.  If I understood your description properly, here's the result:

I've attached the model in Inventor 2018 format.

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Sam B
Inventor Pro 2020.1 | Windows 7 SP1
LinkedIn

[jrl5735]

Agghhh...

You did understand my post, quite well. Thanks for that.

After looking at what you did, I realized I was thinking wrong. The slopes should match top and bottom. Not mirror each other. The outside thickness doesn't need to be 3/4", but the thickness at the hole does need to be 1/8". So, the piece should be 1/8" thick throughout the piece.

The hole not being centered can't be avoided as it's already in place.

Man, I wish I knew inventor! You're drawing tells the whole story, rather than me trying to figure out where exactly things start and stop. Nicely done.

[SBix26]

Maybe this is closer to what you need?  2018 format model attached.  Unable to embed an image, sorry to say.

[jrl5735]

The results are exactly what I expected. There would be a small bit at the top and bottom right corners were there wouldn't be any material for the angle to reach.

Thanks for that. Sadly, the guy who would cut the piece says it would be extremely difficult to cut both sides.

He would have a difficult lining it all up.

I don't know about cnc machines and using stp files, so I'll take his word for it.