V0.18 Challenge--Clerget 9B Aero Engine--UPDATE #6

Show off your FreeCAD projects here!
Forum rules
Be nice to others! Respect the FreeCAD code of conduct!
chrisb
Veteran
Posts: 53919
Joined: Tue Mar 17, 2015 9:14 am

Re: V0.18 Challenge--Clerget 9B Aero Engine--UPDATE #2

Post by chrisb »

ppemawm wrote: Tue Jul 24, 2018 9:18 pm
The drawing shows two, one larger half outer helix, and a smaller inner helix on different centerlines. The wrap of the inner helix was adjusted to align the horizontal pad with the valve cap, the horizontal pad was trimmed at the valve cap centerline, and finally, a quarter revolve around the cap finished it off. Not as tricky as it may appear.
Thank you for the details!
A Sketcher Lecture with in-depth information is available in English, auf Deutsch, en français, en español.
User avatar
tanderson69
Veteran
Posts: 1626
Joined: Thu Feb 18, 2010 1:07 am

Re: V0.18 Challenge--Clerget 9B Aero Engine--UPDATE #2

Post by tanderson69 »

I don't think you can do this in freecad but occt did make this variable blend.

rockerTA01.png
rockerTA01.png (17.97 KiB) Viewed 2594 times
Attachments
rockerTA01.brep.zip
(200.12 KiB) Downloaded 89 times
Jee-Bee
Veteran
Posts: 2566
Joined: Tue Jun 16, 2015 10:32 am
Location: Netherlands

Re: V0.18 Challenge--Clerget 9B Aero Engine--UPDATE #2

Post by Jee-Bee »

Feature request :D
User avatar
microelly2
Veteran
Posts: 4688
Joined: Tue Nov 12, 2013 4:06 pm
Contact:

Re: V0.18 Challenge--Clerget 9B Aero Engine--UPDATE #2

Post by microelly2 »

I put the problem into my testcase collection.
I have to extend my face connect to cyclic nurbs to get a smooth connect.
https://forum.freecadweb.org/viewtopic. ... 10#p246470
The idea than is like in Blender: open two round holes in the cylinders and connect them by a nurbs tube.
bp_842.png
bp_842.png (51.29 KiB) Viewed 2566 times
User avatar
NormandC
Veteran
Posts: 18587
Joined: Sat Feb 06, 2010 9:52 pm
Location: Québec, Canada

Re: V0.18 Challenge--Clerget 9B Aero Engine--UPDATE #2

Post by NormandC »

NormandC wrote: Tue Jul 24, 2018 7:04 pm Unfortunately, this sweep is not perfect. The rear is not perfectly straight. Just to find out, I placed a large cube tangent to both cylinders and made a Part Cut.

You can see where the sweep was exceeding the line, the cut generated two planar faces (in grey).
NormandC wrote: Tue Jul 24, 2018 7:38 pm It's not working for me, creating PD fillets after a PD Mirrored feature fails.
I solved these two things that were bugging me.

I changed the AdditiveLoft for an AdditivePipe, no good reason, I just wanted to have a planar face underneath so a refine would work with the other faces (Loft never creates planar faces between sections). I know, it's silly since this planar face is going to get consumed by the mirror! :D For the second AdditivePipe, the solution to making it straight at the rear was ridiculously simple: rather than use the front arc as path, use the rear straight edge. Duh!

To make the fillets succeed, I had to sacrifice tangency of all the ends between the cylinders. In the master sketch, I made the circle 0.01mm smaller in radius.

Now I have a mirrored model entirely made in PartDesign. And it has a smaller file size.
Attachments
ppemawm_exhaust_rocking_lever_test_nc2.fcstd
(505.88 KiB) Downloaded 102 times
User avatar
ppemawm
Veteran
Posts: 1240
Joined: Fri May 17, 2013 3:54 pm
Location: New York NY USA

Re: V0.18 Challenge--Clerget 9B Aero Engine--UPDATE #2

Post by ppemawm »

NormandC wrote: Thu Jul 26, 2018 6:56 am Now I have a mirrored model entirely made in PartDesign.
Thanks NormandC for the follow-up.
I must say that every time I read one of your posts I learn something new.

One question, why use datum planes in this example if you can attach the sketches in the same manner?
Note: The 3 mm fillet fails on Recompute in my version which is a bit behind the latest.

OS: Windows 10
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.18.13983 (Git)
Build type: Release
Branch: master
Hash: 8f1c6f77c090ae7d9c2bfd4f18811083b01a3eb2
Python version: 2.7.14
Qt version: 4.8.7
Coin version: 4.0.0a
OCC version: 7.2.0
Locale: English/UnitedStates (en_US)
"It is a poor workman who blames his tools..." ;)
User avatar
NormandC
Veteran
Posts: 18587
Joined: Sat Feb 06, 2010 9:52 pm
Location: Québec, Canada

Re: V0.18 Challenge--Clerget 9B Aero Engine--UPDATE #2

Post by NormandC »

ppemawm wrote: Thu Jul 26, 2018 11:36 am One question, why use datum planes in this example if you can attach the sketches in the same manner?
Ah, for convenience, mostly. I haven't found a way to directly attach a new sketch to anything else but a plane. So without using a datum plane, I'd have to first create a new sketch on a plane, close it then edit its attachment mode, and finally go back to sketch editing mode. It's a hassle.

ppemawm wrote: Thu Jul 26, 2018 11:36 am Note: The 3 mm fillet fails on Recompute in my version which is a bit behind the latest.
I'm not surprised. Before adding the Mirrored feature, I tested fillets first; I couldn't make a 3mm fillet there successfully, the highest it would go was 2.9.

After the Mirrored, the 3mm fillet worked, and I ran with it... Should have checked. OCC's fillets are sure finicky.

I worked in 0.17.13522 on Ubuntu, on which OCC was recently upgraded to 7.3.0. I don't know if it could be related.
User avatar
ppemawm
Veteran
Posts: 1240
Joined: Fri May 17, 2013 3:54 pm
Location: New York NY USA

Re: V0.18 Challenge--Clerget 9B Aero Engine--UPDATE #2

Post by ppemawm »

NormandC wrote: Thu Jul 26, 2018 3:32 pm So without using a datum plane, I'd have to first create a new sketch on a plane, close it then edit its attachment mode, and finally go back to sketch editing mode. It's a hassle.
Totally agree but do not like the idea of all the extra baggage of datum planes if not needed, especially in a project of this size.

What I have been doing (after about 500+ sketches you can do it in your sleep):

Create sketch.
Select any plane.
Slow double click Okay button. This opens and closes the sketch.
Open the map mode in the Property Panel.
Set attachment mode and offset.
Reopen sketch.

It's a hassle, indeed.
"It is a poor workman who blames his tools..." ;)
User avatar
NormandC
Veteran
Posts: 18587
Joined: Sat Feb 06, 2010 9:52 pm
Location: Québec, Canada

Re: V0.18 Challenge--Clerget 9B Aero Engine--UPDATE #2

Post by NormandC »

ppemawm wrote: Thu Jul 26, 2018 6:28 pm Totally agree but do not like the idea of all the extra baggage of datum planes if not needed, especially in a project of this size.
I understand completely! I only did a 550KB part, not a 116MB mammoth assembly!

ppemawm wrote: Thu Jul 26, 2018 11:36 am The 3 mm fillet fails on Recompute in my version which is a bit behind the latest.
NormandC wrote: Thu Jul 26, 2018 3:32 pm After the Mirrored, the 3mm fillet worked, and I ran with it... Should have checked. OCC's fillets are sure finicky.

I worked in 0.17.1352228 on Ubuntu, on which OCC was recently upgraded to 7.3.0. I don't know if it could be related.
Just tested with the 0.17.13522 AppImage, which is based on OCC 7.2.0. After a recompute, same as you, the 3mm Fillet feature breaks. The biggest value it will accept is 2.90mm.

With OCC 7.3.0, no problem recomputing; but 3.2mm is the highest possible value, over that the Fillet fails.

OS: Ubuntu 18.04.1 LTS
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.17.13528 (Git)
Build type: None
Branch: releases/FreeCAD-0-17
Hash: 5c3f7bf8ec51e2c7187789f7edba71a7aa82a88b
Python version: 2.7.15rc1
Qt version: 4.8.7
Coin version: 4.0.0a
OCC version: 7.3.0
Locale: French/Canada (fr_CA)
User avatar
ppemawm
Veteran
Posts: 1240
Joined: Fri May 17, 2013 3:54 pm
Location: New York NY USA

Re: V0.18 Challenge--Clerget 9B Aero Engine--UPDATE #3

Post by ppemawm »

The engine proper is finally beginning to come together. All of the major subassemblies are now complete with the exception of the remaining accessories (oil/air pumps and magnetos). The last assembly to be completed were the reciprocating components: piston assembly, master connecting rod, and the slave rods. These were all quite straight forward except for some filleting of the master/slave rods which I simply could not model with a valid solid.

A few screenshots of the recent progress with some brief comments:

This is a shot of all the assemblies made visible.  Note the use of the Part containers for logical sub-assemblies which makes it quite convenient to quickly change the displayed geometry as well as to conveniently explode the assembly if desired.<br /><br />The crank handle located on the lower part of the engine, geared to the distributor, is for manual start.  Can you imagine trying to turn this guy over by hand?
This is a shot of all the assemblies made visible. Note the use of the Part containers for logical sub-assemblies which makes it quite convenient to quickly change the displayed geometry as well as to conveniently explode the assembly if desired.

The crank handle located on the lower part of the engine, geared to the distributor, is for manual start. Can you imagine trying to turn this guy over by hand?
Picture17.jpg (192.76 KiB) Viewed 2302 times
This is an exploded view of all the sub-assemblies created thus far by simply changing the 'X' placement of the Part Containers in the Data tab of the Combo View/Property panel.  <br /><br />These have been exploded pretty much in the same order as one would assemble the engine, thus the logic in the Tree organization.
This is an exploded view of all the sub-assemblies created thus far by simply changing the 'X' placement of the Part Containers in the Data tab of the Combo View/Property panel.

These have been exploded pretty much in the same order as one would assemble the engine, thus the logic in the Tree organization.
Picture18.jpg (190.57 KiB) Viewed 2302 times
Modelling the piston and connecting rod components was rather straight forward.  The master rod came first, then a slave rod (#2), and finally the piston components located on the master rod.  The master rod piston sub-assembly was then cloned and each were rotated in increments of 40 deg about the engine (global) centerline.  This kept the pistons centerlines true to the cylinders.  They were then relocated using Y &amp; Z Placement properties to the center of the slave rod ends.<br /><br />The #2 slave rod was located according to a master sketch which was constrained by the slave rod geometry and the cylinder radial centerlines.  This was then cloned and rotated about the crankshaft journal in increments of 38 deg for the #3-#9.  Each were then rotated about its wrist pin to the centerline of its respective cylinder.<br /><br />The gudgeon piston pins and bolts had to then be rotated about the gudgeon centerline separately to align them with the piston, again, using the Placement properties.  Simple enough to do but a bit tedious for nine cylinders.<br /><br />Note that there are some quite close clearances (&lt;3 mm) when the pistons rotate through the bottom of the cycle.  French engineering at its best!
Modelling the piston and connecting rod components was rather straight forward. The master rod came first, then a slave rod (#2), and finally the piston components located on the master rod. The master rod piston sub-assembly was then cloned and each were rotated in increments of 40 deg about the engine (global) centerline. This kept the pistons centerlines true to the cylinders. They were then relocated using Y & Z Placement properties to the center of the slave rod ends.

The #2 slave rod was located according to a master sketch which was constrained by the slave rod geometry and the cylinder radial centerlines. This was then cloned and rotated about the crankshaft journal in increments of 38 deg for the #3-#9. Each were then rotated about its wrist pin to the centerline of its respective cylinder.

The gudgeon piston pins and bolts had to then be rotated about the gudgeon centerline separately to align them with the piston, again, using the Placement properties. Simple enough to do but a bit tedious for nine cylinders.

Note that there are some quite close clearances (<3 mm) when the pistons rotate through the bottom of the cycle. French engineering at its best!
Picture19.jpg (170.92 KiB) Viewed 2302 times
The photo inset is of an actual slave rod from a 1920's engine.  The large fillet on the same side as the bolt hole was easy enough to produce with a pocket, but the secondary fillet shown by the arrow at the intersection of the conical chamfers and the rod cylindrical surfaces failed to produce a valid solid.<br /><br />The small fillet on the master rod was not a problem but combining that with the conical and cylindrical surfaces after the pocket for the large radius failed which is all a bit frustrating.  If a machinist can make it, I should be able to model it.
The photo inset is of an actual slave rod from a 1920's engine. The large fillet on the same side as the bolt hole was easy enough to produce with a pocket, but the secondary fillet shown by the arrow at the intersection of the conical chamfers and the rod cylindrical surfaces failed to produce a valid solid.

The small fillet on the master rod was not a problem but combining that with the conical and cylindrical surfaces after the pocket for the large radius failed which is all a bit frustrating. If a machinist can make it, I should be able to model it.
Picture20.jpg (168.73 KiB) Viewed 2302 times
This is another fillet on the slave rods which would not always succeed in a valid solid as shown by geometry check (BOP enabled).  <br /><br />I suppose this may have something to do with the seam on the cylinder of the lower portion of the rod.  I have not tried to rotate this away from the fillet yet to see if that matters.  It worked ok on the master rod!<br /><br />Note that Draft&gt;Arrays&gt;Polar were used for the master rod wrist pins and bushings rather than clones since they did not have to be relocated like the slave rods.
This is another fillet on the slave rods which would not always succeed in a valid solid as shown by geometry check (BOP enabled).

I suppose this may have something to do with the seam on the cylinder of the lower portion of the rod. I have not tried to rotate this away from the fillet yet to see if that matters. It worked ok on the master rod!

Note that Draft>Arrays>Polar were used for the master rod wrist pins and bushings rather than clones since they did not have to be relocated like the slave rods.
Picture21.jpg (136.35 KiB) Viewed 2302 times
.
The file has grown to 133 Mb, 646 Sketches, and 191 Bodies, but performance is still adequate. No crashes, stable as can be. The only problem with such a large file is the (~4 min) required for autosave every 15 minutes and during some random recomputes triggered somehow. Perhaps someone could come up with a way to make this an incremental save? Then again, who else would want to have everything in one file?

Now, on to the accessories which I may put in a separate file due to their complexity. Stay tuned for more updates.

OS: Windows 10
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.18.13983 (Git)
Build type: Release
Branch: master
Hash: 8f1c6f77c090ae7d9c2bfd4f18811083b01a3eb2
Python version: 2.7.14
Qt version: 4.8.7
Coin version: 4.0.0a
OCC version: 7.2.0
Locale: English/UnitedStates (en_US)
"It is a poor workman who blames his tools..." ;)
Post Reply