Designing oil sump fins

[masterkorp.alfredo]

Hello everyone,

I was doing some inner fins to control the oil flow inside my custom oil sump.

Here are some pictures of the fin structure:




But I realized how painful doing this by hand will be. Just making the holes with dremel will take me at least 20 hours of work. So I am thinking on designing the full piece in FreeCAD, then convert the 3D with 2D planes to send to CNC laser cutting, so i would just weld the pieces together.

Before starting do you have any suggestions on do design the piece ?

My FreeCAD info:

OS: "Arch Linux"
Word size: 64-bit
Version: 0.14.3702 (Git)
Branch: releases/FreeCAD-0-14
Hash: b3368125c63289ec8ce9faec2b2ae4c78d436406
Python version: 2.7.9
Qt version: 4.8.6
Coin version: 3.1.3
SoQt version: 1.5.0
OCC version: 6.7.1

[drei]

Just tips on basic design, in no specific order.

• Simplify. Start with the basic shape or contour of your object.
• Separate the workpiece into separate steps. First, an extrusion, second a hole, etc.
• Do fillets last. They tend to mess up stuff, so leave for last.
• Check how your model history is. Most often people break their design by not mapping sketches to faces and end up with weird results.
• When in doubt ask. Perhaps we'll take some time to answer, depending on how hard the question is, but its best to ask for advice and fix errors when in an early face of design than to doing it last.
• Prefer vertical and horizontal lengths. They're easier on the sketch solver, so no risk in killing FreeCAD from hard to solve computations.

[masterkorp.alfredo]

So while designing the CAD I've encountered 2 problems:



Like I "illustrated" on the screen shot I would like for the left pad to have the same length as the right pad, no matter what angle is it from it.

Right now to proceed with the design I be calculating this by hand, but is there a way to directly constraint this in FreeCAD?

Another question is how would I constrain the angle of the left pad from the right if there was no bottom bad?

The CAD file goes attached.

Any suggestions would be very welcome.

[drei]

Like I "illustrated" on the screen shot I would like for the left pad to have the same length as the right pad, no matter what angle is it from it.

Thankfully this command exists:
Constraint_EqualLength

First you'll need to create an external geometry reference (see here), seeing as you made the pads in different Sketches.

I'll see how to solve your other problem a bit later, currently I'm compiling so it may take a while.

[masterkorp.alfredo]

Thankfully this command exists:
Constraint_EqualLength

I think the equal constraint may not be the solution here. I may have not explained myself correctly. The light from the right pad will have the same "height" but not the same length as the left pad since they're not parallel to each other.

First you'll need to create an external geometry reference (see here), seeing as you made the pads in different Sketches.

I've tried the external sketcher, but I could not make a line to that edge.

I'll see how to solve your other problem a bit later, currently I'm compiling so it may take a while.

Thank you for your input. I will be waiting for a reply.

[NormandC]

Hello,

You have not posted your FreeCAD info like recommended in the "Please read first" topic, therefore I don't know if you're using the latest version of FreeCAD. We have released v0.15.4671 this week. If you haven't done so, I recommend you upgrade.

Which reminds me I need to update the "read first" topic.

[masterkorp.alfredo]

Hello,

You have not posted your FreeCAD info like recommended in the "Please read first" topic, therefore I don't know if you're using the latest version of FreeCAD. We have released v0.15.4671 this week. If you haven't done so, I recommend you upgrade.

Which reminds me I need to update the "read first" topic.

Done thanks!

[NormandC]

Thanks! On Arch Linux, I have no idea when you'll get the update. Since it's a rolling release, I guess that'll be pretty soon.

[masterkorp.alfredo]

Thanks! On Arch Linux, I have no idea when you'll get the update. Since it's a rolling release, I guess that'll be pretty soon.

Is there any specific advantage in upgrading for this particular design ?

If there is, I will just compile from the freecad-git package (gets the lastest git version)

[drei]

Here's my proposition to your file. I also noticed you broke the dependency graph when you created Sketch.
You can view the dependency graph in Tools > Dependency Graph