Learning Autodesk Fusion 360, the hard way

[XaviG]

This is my first post in the community, to hear your advice on how would you proceed from now on...


I did not custom made the bike frame, but tried to 3D model it once I received the bike in order to shape my mental design of the battery holders, the main problem wasn't having zero experience and background in the task which I don't, but to not double check all the measurements at the very moment I finished the frame sketch.


After double checking the CAD measurements of the frame and the inner triangle length, it does not match at all with reality.


Now I see the main fault was to use the manufacturer angles for my frame size instead of obeying to the angles I extracted myself taking a picture of the bike.


The battery manufacturer provided me the .step file but I regret to not have asked before having the entire modeling done, I also asked for the .step file to the bike manufacturer which I think may have no interest or it may go against the company rules, but no answer for now.


I believe I can somehow subtract volumes for each of the 3 battery holders, using the battery .step file to cut through them, and at least ensure a perfect fit between battery and holders.


The frame angles are way off and that's the very reason why I come to ask for your advice since reverse enginering may be not my thing, maybe a 3D scaner may have helped from the very beggining and I am not sure about the precision of extracting the angles with a photo and a phone app.


I spent a week figuring out how to 3D model it and I am not afraid of spending another week or whatever it takes to have a serious V1 candidate for the holders printings, but I am afraid to keep working on wrong measurements despite it sure will be a precious learning.


 I would like to present the project properly on the ebike builds section as soon as having the 3D parts printed but I can say it's a beautiful one for a commuting bycicle,


It's made around the maintenance free idea, slow winding torque sensing fat DD, belt, gearbox, rigid frame/fork, 29x2.60 tires, fenders, lights and a 7kg 1260Wh 52V 40A+ automotive grade battery on Samsung 50S cells pulling 8A/cell at 30% of it's max continuous discharge when wide open throttle.


I would like to see very little voltage SAG, but let's see If by mostly cycling 20 to 80% SOC they last more than the certified 200 cycles by Samsung, well aware of the optimism labeling them as true high power cells, they clearly don't have the best IR anywhere near the 20A despite being labeled as 25A max continuous, but at max 8A draw it should be an excellent cost/efective choice,


Wish me luck

 

[TPEHAK]

You might better to learn and use Onshape instead. It is more advanced, more professional, more accessible and free and you can share your design online including the whole build tree if you need to ask something.

 

[scianiac]

You might better to learn and use Onshape instead. It is more advanced, more professional, more accessible and free and you can share your design online including the whole build tree if you need to ask something.

I would rank Onshape above Fusion but only because they haven't held users hostage yet, I have no doubt they will at some point though. I've been looking for a new CAD option for awhile now but honestly they all have so many issues I've kind of given up for for a little. I just can't justify ever using a cloud based CAD program, the idea that all my work could be held hostage at any point is a hard deal breaker.

Anyway, one way I've used in the past to confirm my CAD bike model is correct for battery fitment was to laser cut a piece of cardboard that is the size of the triangle. Now I'm guessing you don't have a laser cutter but it's not too complex a shape so if you measure accurately you can draw it on some cardboard and cut it out.

 

[offGridDownUnder]

The cardboard idea is useful and accessible. I'll mention foamcore board as well - that's rigid foam faced with paper on both sides - easy to mark, work with, and glue to. I find that in art supply stores.

I'll also mention building up a pattern. Attach pieces of board accurately to one reference (axis of cranks, top of stem tube, etc.), then bridge the various pieces with more board gluing or taping it securely so that you can remove the entire collection to a table for accurate measurements.

In extreme cases, I would consider removing the cranks to reference the axle itself or even build up a replacement bottom bracket assembly with a clear axial point to measure from - but that is extreme.

Think of attaching a bracket to a piece of foamcore or cardboard and fastening that with a bolt into a mounting point, such as a threaded insert on the frame to accurately position the foamcore. In this way, you can build up accurate, repeatable, measurements to solid mounts.

Once I have my measurements, I put them into AutoCAD (ex-employee, so I have my own copy). I keep intending to learn a modern 3D system, but 'the devil you know'.

I've also made parts out of foamcore - such as a drum that enclosed the volume of my motor plus a centimeter on the radius to represent the safe volume the motor will sweep to provide a basis for positioning the motor axis - then build up the mounting to hold it from there to the anchoring points.

Up to you how much time you want to spend on which approach for what results.

 

[99t4]

Agree on the usefulness of a cardboard template. My favorite glue of choice is hot glue gun. Sets up nearly instantly and can add to the rigidity. Sometimes we can get seduced into going overboard with hi tech tools (not saying you're doing that here OP) where simpler methods might be faster, easier, and just as reliable.