Location: Montreal, QC. (currently expat to Shanghai)
Posts: 3,249
Quote:
Originally Posted by jaykay
Jeez Fredric ......did you make them integrate a CAD station in your hostpital bed
Dude I think its what they put in the cheese these days :/
Already at balancing this assembly Jay. Doing the 1800RPM(223km/hr) currently. Hopefully be done with counter-weighting the center/badge by tomorrow so I can (finally) send this to CAM. I'm actually really eager to see them myself.
Secret: good tools man... makes for an easy job. Prototypes are always spot on
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'97 Boxster base model 2.5L, Guards Red/Tan leather, with a new but old Alpine am/fm radio.
Holy Cow!!! Just caught this thread. Two questions, when will they be ready and how much? Oh heck, forget how much just when will they be ready? Great work, absolutely wonderful...
Location: Montreal, QC. (currently expat to Shanghai)
Posts: 3,249
Quote:
Originally Posted by kjc2050
Yikes. Beautiful!! Fred, your work is amazing.
Kevin, too kind brother
Quote:
Originally Posted by steved0x
Holy crap I want these!!!
Me too, I think lolll Very humble piece of kit from the wheel/cap visuals that came out yesterday.
Quote:
Originally Posted by PaulE
A touch of red on my seal gray car with silver wheels will look nice I think!
Same here. Boxster have the blue CGT caps on since 3 years, time for red I think
Quote:
Originally Posted by jakeru
Nice work - Fred - love seeing your techniques!
Thanks bud! Not done, far from it actually. Subscribe if you haven't done so because there is so much more coming. I'll soon be starting the CAM work, fixtures, sourcing the correct materials for prototyping, we'll machine this using the High Speed machining center (Siemens controllers), We'll also laser-mark this cap with something sexy, etc etc. Planing to hit the shop floor in a week! Plenty of fun to come, stay tuned
Quote:
Originally Posted by Jgkram
Holy Cow!!! Just caught this thread. Two questions, when will they be ready and how much? Oh heck, forget how much just when will they be ready? Great work, absolutely wonderful...
Too bad folks doesn't do the DYI section of the forum as much as the General one. No price yet, let's machine all this together, get quotes on materials and that will eventually define the end price. So far we are looking at a pretty cheap-to-manufacture part... I'll try my best to keep it that.
Not hidding anything, everything is real here so what I pay for my caps is pretty much what you'll also pay for yours
Quote:
Originally Posted by rfuerst911sc
Fred congrats on getting better keep healing and moving forward ! I may have missed it but how are you adding color to the parts ?
Thanks Rick, yup getting better by the week. If I don't get hit by a lightning (i.e my type of luck recently) I should be back to 99% same in less than 12 months. Wish me luck man lolll The main cap will be 6061 aluminum and anodized in the color of your choice (gun metal, red, blue, black, etc). The center where the P shield is should ideally remain silver (clear anodized). Fully custom mate, so if the beast needs something unique I'll be 100% able to provide that for you bud
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'97 Boxster base model 2.5L, Guards Red/Tan leather, with a new but old Alpine am/fm radio.
Location: Montreal, QC. (currently expat to Shanghai)
Posts: 3,249
Multiphysics Simulation - Assembly Balancing
Just a few visuals on the assembly balancing and a video showing my highly guarded & secret Newton's Cradle below. Run the vid half way to see the motion of the center cap. Just quick visuals for you guys, sorry, not the full thing (man, this is all time consuming this pic/vid/encoding thing loll).
Simple you may think but incurably powerful. Pure physics; 60+ years old solvers (NASA(nastran), Recurdyn, Adams, etc). Its all about the quality of the solvers really.
^ Here you can see the assembly I use for balancing rotary parts. It’s a base having a shaft rotating in the X axis. Not specific to the center cap I am doing now, I’ve actually used this for quite a few other parts successfully (custom spacers, CNC tool holders, custom rotary chucks soft jaws, center caps, etc etc).
^ The shaft uses a driver (motor) set at 2,400RPM for this test. You can however set this to pretty much anything between 0 ~ 999,999,999rev/sec. Here we are testing vibration on a Porsche wheel with a diameter of 660MM (26"), or a circumference of 2073mm (660*PI). In velocity, and if spun at 2,400RPM, this gives us 82,938mm/sec (or 298km/h). So the target here is to rate the Great Center Cap for speed of 300Km/h without any sort of vibration.
^ First thing first, calibrating the shaft coupled with the Porsche wheel hub (translucent part; right end side). We should be getting a flat line e.g. no changes in force magnitude anywhere = zero vibration.
^ With all the parts of the assembly inserted into the wheel hub, we are getting a vibration in the Z axis (i.e. up/down). So by deactivating each part of the assembly, it is easy to figure out which part is causing the wiggle. In the case of this assembly, the Center holding the P badge is the culprit.
^ To make things a bit easier visually, we slow down the motion solver to 1 (one) rotation only so we can clearly see the vibration curve. Still rotating @2,400RPM (40rev/sec) however the time steps drops from 1 sec down to 0.025sec (e.g 1sec / 40rev per sec). So 1 full revolution only here. Easier to see than the above graph!
^ Now having found the culprit, you need to go back to the drawing board and counter-weight the part. In this case material had to be removed (orange). Once the center of mass gets back to zero, you re-import the part and re-solve the motion.
And BINGO!
^ As you can see, we are now getting 100% flat line per revolution (still at 2,400RPM). The badge is set to 50% transparent so you can see where the little pocket is located.
At the manufacturing stage, a very small pocket will need to be machined inside the area where the P badge goes and all will go back in perfect balance!
And that is how we design rotating parts and balance them using Multiphysics Motion Simulation ladies and gent. Fairly elementary and simple lollll
VIDEO
You'll see my Newton's Cradle in there (not a toy!). Again; incredibly powerful. CAE allows us to export Flexible Bodies (e.g. response dynamics) and import those inside Motion Sim. That is how we get table field of data for various materials used for creating parts (forces, damping, etc). This data is then used down the line for crash/impact analysis, fatigue analysis, stuff like that. Could be wrong but I think every engineers have a Newton's Cradle modeled (can't be found anywhere, you got to make your own and mine's not for sale loll)
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'97 Boxster base model 2.5L, Guards Red/Tan leather, with a new but old Alpine am/fm radio.
Fred congrats on getting better keep healing and moving forward ! I may have missed it but how are you adding color to the parts ? Does the raw material already contain the color ? Or are they going to be painted ? And what colors will be available ? I think " the beast " needs a set of these but I'll have to figure out the color . Thanks for what you add to the forum and community .
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2002 Boxster S Arctic Silver with black top with glass window and black leather interior. Jake Raby 3.6 SS ( the beast ) with IMS Solution. 996 GT3 front bumper , GT3 rocker covers and GT3TEK rear diffuser and Joe Toth composites rear ducktail spoiler .
Now that's very counter-intuitive to me that on a perfectly symmetric looking object, that the lightening relief would be positioned off the line of symmetry. Any explanation as to why, Fred?
Also, I find it interesting that you've modeled a balancing apparatus. Wouldn't it be just as easy to assume the piece is sitting there in space and rotating by some strictly defined (assumed unmoveable) axis? I suppose with your method, you could model flexibility and oscillations of the testing jig, but I'm not sure why that would be useful, unless you were doing real-world testing on the same exact jig and wanted to somehow model very similar predicted results. At some point, the model needs to assume things are fixed. Would this simulation assume the base feet of the testing jig are fixed?
I remember getting some unversity mechanical engineering grad student to help do some FEA simulation work on designing a lightened version of wheel centers for an autocross race car I was running. This was at least 10 years ago, so the tools were a bit more rudimentary to what you seem to have access to. I don't remember using using any solvers, but rather, just manually iterated the design a few times until we were happy. The machined weight of those wheel center came out just as predicted! Very cool and memorable experience for me. So thanks for sharing your fascinating techniques.
Location: Montreal, QC. (currently expat to Shanghai)
Posts: 3,249
Quote:
Originally Posted by jakeru
Now that's very counter-intuitive to me that on a perfectly symmetric looking object, that the lightening relief would be positioned off the line of symmetry. Any explanation as to why, Fred?
Also, I find it interesting that you've modeled a balancing apparatus. Wouldn't it be just as easy to assume the piece is sitting there in space and rotating by some strictly defined (assumed unmoveable) axis? I suppose with your method, you could model flexibility and oscillations of the testing jig, but I'm not sure why that would be useful, unless you were doing real-world testing on the same exact jig and wanted to somehow model very similar predicted results. At some point, the model needs to assume things are fixed. Would this simulation assume the base feet of the testing jig are fixed?
I remember getting some unversity mechanical engineering grad student to help do some FEA simulation work on designing a lightened version of wheel centers for an autocross race car I was running. This was at least 10 years ago, so the tools were a bit more rudimentary to what you seem to have access to. I don't remember using using any solvers, but rather, just manually iterated the design a few times until we were happy. The machined weight of those wheel center came out just as predicted! Very cool and memorable experience for me. So thanks for sharing your fascinating techniques.
Thanks Jake
RE modern solvers; the owner and its backend software engineers claims that this is what puts on the Mars Rover (Curiosity) where it is today and also what makes most of today’s jet planes takeoff and land safely. I’d love to challenge these statements but dare lolll
The jig’s base is indeed ‘fixed’ with 9806.65mm/sec2 gravity acting on it – not floating bud. The shaft/bushings also needs mu-static, dynamic and stiction velocity/deformation (aka friction) properly defined and enabled otherwise nothing works…. the shaft will bounce passed the 500rpm. Real-life no, I agree, but certainly real-world multiphysics (well, this world anyway).
RE Center caps, they are ‘visually’ symmetric yes but as you saw in the vid, the center (p badge) is not 100% aligned with the center of mass (taking gravity into account here). That is due to the non-symetric feature/pocket for the badge. Anyhow, it is very unlikely that a perfectly symmetric center cap (center of rot) are going to throw your wheel out of wack however best practices force me to ensure that the design is meeting ‘base line’ quality. I am sure that potential buyer will appreciate this.
OT; a year ago I’ve designed a special tool holder that had to mount into a 40,000RPM spindle. The tool was designed and meant at machining a part within 2micron tolerance using a carbide endmill of 0.2mm diameter – read very (very) small. It was for a medical device/part, something that brother in law here specialize into. Multiphysics balancing in this case greatly help i.e. less material had to be removed once the tool was dynamically balanced (real-life) afterward. We’ve seen ‘dust’ amount of material removal to get it balanced in the 4DOF. That said it does serve a purpose, in some more extreme cases, but perhaps not so much for center caps that only spin <3k rpm lollll
All good fun bud!
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'97 Boxster base model 2.5L, Guards Red/Tan leather, with a new but old Alpine am/fm radio.
Location: Montreal, QC. (currently expat to Shanghai)
Posts: 3,249
Material sourcing and CAM
Soon off to the manufacturing finally. I've already ordered the material so I should be getting this hopefully latest tomorrow afternoon. Once I have the size of the stock material I'll trow all of this in the CAM processing.
That should be a bit more interesting, and much less geaky I promisse. Personally, that is my favorite part... shaping hard metal, making chips fly everywhere, noises, bad burning smells, etc lollll
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'97 Boxster base model 2.5L, Guards Red/Tan leather, with a new but old Alpine am/fm radio.
![Custom Center Caps for Porsche Wheel [from CAD, prototyping to finish]](/forums/iconimages/diy-project-guides/custom-center-caps-porsche-wheel-%5B-cad-prototyping-finish%5D_ltr.gif)
Boxster S
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2004 Porsche Boxster S
2004 Porsche 996 Targa
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