289/302 Ford V-8 enginee

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awake

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Great work - as always!

On PLA vs PETG ... I like using PETG, and get good results with it, but PLA is a LOT stronger than people often realize. Various YouTube tests have confirmed that it can be stronger than other filaments that people typically assume will be stronger ... a recent video came out with nearly equal results for PLA and nylon+carbon fiber.

Of course, there are a lot of variables involved - print temperature being a key, and exactly what type of strength is being measured. PETG is much tougher, in that it will bend much further without breaking; it will also bend much more easily than PLA. Sometimes that is an advantage ... sometimes not. I would say PLA is a better choice for this project than PETG would be.
 

Eccentric

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Thanks for the files George. I am really impressed with them, I was surprised with how many there are. The detail is crazy awesome, inside and out. I hope my 3D print turns out as well as yours did. I'm going to have me some fun.
 

gbritnell

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In some responses it was suggested the engine was a little anemic with just a 2 bbl. carb on it so how about a set of 40mm IDF Webers. I just finished the manifold and got it assembled.
 

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mrehmus

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In some responses it was suggested the engine was a little anemic with just a 2 bbl. carb on it so how about a set of 40mm IDF Webers. I just finished the manifold and got it assembled.
It was anemic until I put a 500CFM Holly on my 1968 full-size 4-door.
 

gbritnell

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I have been doing solid modeling for quite some time. I did it when I worked but had been away from it for a long time. When i got Solidworks I had to learn it's uniqueness compared to the programs I had been using. For most of the parts on the 302 engine I didn't have much trouble modeling them except for a few instances but then I decided to make a set of shorty equal length headers. I gathered pictures from the internet and started making 2d drawings to layout dimensions and shapes. I must say that working with all the curves and points in space had me practicing as much as the actual modeling. I went to the old standby, Youtube, but all of the videos I needed were being done by someone who had done it many times and just assumed you could follow along. Then there is the accent problem of some of the presenters. Anyway except for a couple of shape deformities I got them done. Another problem is that the left and right aren't just mirrors they are two totally different shapes.
As a side note if someone knows a good video about lofting please let me know. I have a large book I purchased about Solidworks but it doesn't go too deeply into lofting.
Anyway here's the results.
 

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Basil

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That is very impressive George. The lofting tool certainly is very powerful but I also find it somewhat temperamental. I need to make changes to my header model but have been putting it off and going on with parts that are not quite so frustrating. Like anything else I am sure the results will come with time and persistence on my part.
Your CAD abilities certainly are spurring me along with my big block chevy project.
Thank you 👍
 
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Zeb

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Nice work George! Looks really good. Would love to take a crack at this engine on my resin printer! Not sure if you need help by the looks of the other pipes, but I'll take the risk and chime in.

I've found the Alias site extremely helpful. A lot of the math and most terminology transfers.
The youtube channel 36 verts is my go-to for theory. He explains the why and concepts transferred easily to other packages. I've done a lot less shotgun clicking and praying after binge watching... be warned though, it is cruel on the mind. 🤓

This is my typical workflow for troubleshooting kinks on lofts...
  • Sketch planes for your circles on either end should point towards the guide or the work. Some devs might auto fix that under the hood, so maybe not a big deal.
  • Profiles (your 2 circle shapes) should have the polarities match or there will be a nasty kink in the middle. If you drew a circle shape with points, both ends of the pipe should have the same amount of points (segments are called degrees) or you'll get failures and artifacts.
I think the above two are good in your example, the kink might be in the step below...maybe.
  • Guide (the long curve run) can be attached tangent to each profile circumference, but the opposite side of the pipe will go off course down the road. Adding more guides sort of helps make it look better but still produces kind of crappy results. If you can use the circle center to snap your guide instead, Solidworks should support using that in the settings and your pipe should be uniform. I looked up the Solidworks help and they have a centerline option under the property manager. Not sure if your version does. Another bonus to centerline splines is their lengths are exact, so all your pipes will be easier to match.
  • Remove twist if SW allows you to use control points. NX allowed me to in the example below.
  • Another wild guess...it looks like there's a transition between the straight header and the curved pipes. Upping the tangency from G0 to G2+ might smooth the transition. Not sure how or if those features are connected.
CAD_a.png

Below are 2 attempts during break today using two different functions in NX. I could also use a third "pipe" command buried somewhere.
The left one failed by default as it tried to guess, but I just followed my usual steps above to correct. With lofts, we're always having to guide the math, which is why following tutorials has almost always failed me.

CAD_b.png

Or you can just leave the kink. You would get that in manufacturing if the walls were thin and not enough filler/sand was placed in the tube before bending. :)
 

gbritnell

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Hi Zeb,
Thanks for the thoughtful reply and information.
In creating the pipes the shape at the flange is oblong (round bottom (.730 r), flat top (.94 offset) with radii (,660) connecting the top line to the short verticals that are tangent to the round bottom). This is for bolt clearance. This shape transitions into the pipe shape which is round (.812 r.) For almost each pipe there were different angles and offsets. I first created the oblong shape then exited the sketch environment. I then created the round shape then exited. In Solidworks you can go into a 3d option which allows you to put lines, radii and points in space. I used this to create the connector line from one shape to the other. When constraining the end point of the connecting arc to the shapes they have a pierce option or others depending on what you want. Now you have 3 basic elements for the loft. I found that the connecting arc has to be connected to the profiles in some way or another unlike the sweep command where you can have your guide curve eminating from the center of a shape. Once you invoke the loft command then you can control the start and end constraints by tangent to shape etc. As you mentioned you can also control the shape length by adjusting the sliders. It usually defaults at 1 so you can change the numbers and watch what it does to the shape. When I got those distortions I played with the shape control but I could only get so far. I practiced on a different model by using 2 guide curves but when I did that it would tell me that the curves were invalid. My book shows lofting using several different guide curves but I couldn't get more than one to work.
When I did this as a full time job as a pattenmaker/model maker, the programs we used were just getting into parametric modeling, meaning everything was done with surfaces. When I got my version of Solidworks (student/veteran version) I started teaching myself with books and Youtube. Most 3d programs have a lot of similarities so it was a matter of learning icons and procedures. I enjoy the modeling aspect of the hobby more so than the printing part because that's what I did for years. The printing part is enjoyable because you can see your models come to life.
gritnell
 
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Zeb

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I remember having issues in SW using more than one guide curve. It seemed to have very specific requirements.
The only other thought was have you tried b-splines/style splines instead of arcs and lines? Not sure if it would make any difference, but it might.

I find once I can't get lofts/sweeps to work, I have to delve into the dark side of surfacing.
 
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I have been doing solid modeling for quite some time. I did it when I worked but had been away from it for a long time. When i got Solidworks I had to learn it's uniqueness compared to the programs I had been using. For most of the parts on the 302 engine I didn't have much trouble modeling them except for a few instances but then I decided to make a set of shorty equal length headers. I gathered pictures from the internet and started making 2d drawings to layout dimensions and shapes. I must say that working with all the curves and points in space had me practicing as much as the actual modeling. I went to the old standby, Youtube, but all of the videos I needed were being done by someone who had done it many times and just assumed you could follow along. Then there is the accent problem of some of the presenters. Anyway except for a couple of shape deformities I got them done. Another problem is that the left and right aren't just mirrors they are two totally different shapes.
As a side note if someone knows a good video about lofting please let me know. I have a large book I purchased about Solidworks but it doesn't go too deeply into lofting.
Anyway here's the results.
Hello George,
Your Model looks great!
a while ago I built the Subaru WRX EJ20 Boxer Engine Model from Github, it turned out very well on My Photon Mono X 6k resin printer. I would like to give your Model a try if you share the files.
Thorsten
 

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gbritnell

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Hello George,
Your Model looks great!
a while ago I built the Subaru WRX EJ20 Boxer Engine Model from Github, it turned out very well on My Photon Mono X 6k resin printer. I would like to give your Model a try if you share the files.
Thorsten
Hi Thorsten,
Send me a PM for my email address and I will give youthe information about the files
 

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