CNC thread

[Robbie Corbett]

Why do you need to do it at all? (is what I was getting at).

 

[RSRowe]

It does seem an odd way of doing it. Just keep it simple.

I’d stay away from surfaces too.

 

[RSRowe]

Another thing to add.

Keep in mind how difficult that’ll be to make on the CNC, vs a more conventional cylinder, with a thru hole, and boss out the side.

 

[Beauvais Motorsport]

Another thing to add.

Keep in mind how difficult that’ll be to make on the CNC, vs a more conventional cylinder, with a thru hole, and boss out the side.

It’s forged, hence the draft and the flash on the parting line in the scan image.

 

[Robbie Corbett]

Probably drop forged but the surface finish on your scan looks cast.

Does your SOLIDWORKS version have mould tools? You can add a non planar parting line, which lets you create the tooling for either side and add draft angles either side of the parting line.

But it will not, and the designer will not add the flash line. Etc.

 

[botfch]

@Robbie Corbett I take it this is what people mean by sw having its limits? With surfacing that is.

Took me a bit to figure out how to do the parting line draft, made split lines then deleted the faces and used surface fill. Just don't have much control over the surface and you can see it curve in slightly, no undercuts just wish I had more control. I know bmw use catia which this part is by (e90), dont suppose you know if this type of surfacing would be the thing catia could do easily with control?

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Geomagic DX is the software you’d want for that but it’s hella expensive.

It’s based on SW so not sure if some of the tools would translate.

 

[Beauvais Motorsport]

Probably drop forged but the surface finish on your scan looks cast.

Does your SOLIDWORKS version have mould tools? You can add a non planar parting line, which lets you create the tooling for either side and add draft angles either side of the parting line.

But it will not, and the designer will not add the flash line. Etc.

Ignore the scan mate, Im on my old pc and its not done a great job picking up the smooth surface, new pc scans so quickly and the quality of the scan is better.

You guys are absolute legends but I'm not going to start taking loads of pictures of the part and showing you all the angles and elliptical curves to show you why I've done it the way I have and that the deviation analysis of the scan and model is super close, you just have to trust me 😅

 

[Robbie Corbett]

I do trust you and I am positive that the scan and model are very close, you've done a great job modelling the part. What I am asking is why did you need to do such a good job? Does the added geometry need to be modelled for your application?

Basically - when I first started designing things I went to nth level in detail, I felt super proud of my models because they showed every single aspect in detail until one day our most senior designer gave me a coating, I was busy showing him my great threads when he suddenly asked how long it had taken, did the final part benefit from me modelling the threads, did the machining company do a different job when I said M6x1mm in the drawing as apposed to modelling the thread....

I got a bit offended and knobby with him but later thought on it and he was right - it added very little. Now in a turn of events some 15 years later I am in his position and I say the same thing to new designers, they get just as knobby with me as I did with him too 😂

So it comes down to - what it the minimum amount that you can model to achieve your end goals (including goals for evaluation, fit check, simulation and also any rendering).

Are you doing this for fun? In which case awesome, do as much as you can! Or are you doing this with a view to have something made in which case modelling for drop forge when you won't have your replacement part drop forged seems like a waste of your time?

 

[Beauvais Motorsport]

"Does the added geometry need to be modelled for your application?"

I'm not sure what's added about the model so far? How can the molds be machined otherwise? I thought thats how forged/cast/injection molded etc is done, some processes having more importance on some features than others. How the part looks in its physical form for the most part, apart from flash and imperfections is how it was modelled in the first place.

Some of the reasons for this model in particular is to better my cad/designing skill, learn more about the manufacturing processes and why certain features are designed that why, to have a complete assembly of the part for kinematic analysis of the suspension, the bushing has a cold formed 'sleeve', one to the right is similar to the one in this arm, If I don't model the bushing/sleeve then I can't accurately perform kinematic and variation analysis. You could say for kinematics you dont need to model this or that etc, see first 2 reasons.

If I don't ever need to design or have a forged part made then so be it, the knowledge helps me to understand more about automotive engineering, Im not going to uni so I have no other way of doing this.
Every part I'm modelling goes back to what I want to do regarding steering, be it kinematics, variation, natural frequencies, forces/torque etc how it all effects the steering.

I totally get about the new v experienced method of things, especially when it comes to time and money. I always appreciate your advice mate as I know you have the skills!

 

[Robbie Corbett]

Right, so the flash (as you have said) will never be modelled. The split line will be so that you can add a draft angle either side (so the tool can release) and you are right, if the draft is removing material you will need to include it for any stress analysis (or vibration etc).

The split line will be chosen based on the direction of force (or largest force) in use OR chosen to make the part so that it can release from the tooling (no undercuts). Most of the time a designer will aim to simplify tooling as much as possible as that's where the largest initial time/expense is. More often than not the base geometry is created by the designer and then sent to the company who will be moulding/casting/forging the part - they will run their own analysis and decide where to put the split line, where to put release pins, sprues, runners and or gates - that info then goes back to the designer to confirm its ok.

I've had various things injection moulded and I have never designed the tooling, the moulding company has always done that, on some parts I don't even add a draft and ask the moulding company to do that too.

So its entirely possible that the original designer of that suspension part does not have a model which is as accurate as yours 😂

So I 100% appreciate and respect why you are doing this and have done similar before however would also caveat that by saying that for every hour you model this, thats another hour you haven't been able to do your kinematic study which sounds a lot like the main objective of this and for me anyway would be by far the most interesting part.

Check out the mould tools in SW, specifically the parting line as I think that would be an alternative way for you to add the split line and draft.

PS - uni would do nothing but frustrate you imo, you are already a country mile in front of 99% of people coming out of uni, the only thing it really did for me was introduce a load of subjects I didn't know existed, so I could go back to them later in life to self learn what I needed.

 

[Beauvais Motorsport]

Right, so the flash (as you have said) will never be modelled. The split line will be so that you can add a draft angle either side (so the tool can release) and you are right, if the draft is removing material you will need to include it for any stress analysis (or vibration etc).

The split line will be chosen based on the direction of force (or largest force) in use OR chosen to make the part so that it can release from the tooling (no undercuts). Most of the time a designer will aim to simplify tooling as much as possible as that's where the largest initial time/expense is. More often than not the base geometry is created by the designer and then sent to the company who will be moulding/casting/forging the part - they will run their own analysis and decide where to put the split line, where to put release pins, sprues, runners and or gates - that info then goes back to the designer to confirm its ok.

I've had various things injection moulded and I have never designed the tooling, the moulding company has always done that, on some parts I don't even add a draft and ask the moulding company to do that too.

So its entirely possible that the original designer of that suspension part does not have a model which is as accurate as yours 😂

So I 100% appreciate and respect why you are doing this and have done similar before however would also caveat that by saying that for every hour you model this, thats another hour you haven't been able to do your kinematic study which sounds a lot like the main objective of this and for me anyway would be by far the most interesting part.

Check out the mould tools in SW, specifically the parting line as I think that would be an alternative way for you to add the split line and draft.

PS - uni would do nothing but frustrate you imo, you are already a country mile in front of 99% of people coming out of uni, the only thing it really did for me was introduce a load of subjects I didn't know existed, so I could go back to them later in life to self learn what I needed.

Absolutely, I have a subframe here to scan, only need the damper and arb to complete the front end. Just a lot going on at the minute, I tend to do things that arn't the priority as a way to keep busy because I want to be able to put all my focus on the main thing. Having this extra knowledge helps to take the mystery out of things and I feel more confident tackling bigger jobs.

I have the mould tools and need to look at what you said because I am creating the parting line manually using split line. The thing that got me with this particular draft was it being angled, it has to be a partial draft which is why I was using manual methods to gain control over it.

lol thanks man. I was looking at a motorsport engineering course here and in the states, but for me I want to be 50% into the machining side of things which those course dont really do, I would be doing a lot of things unrelated to my interests..

 

[Andy_con]

Finished this on the cnc today