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How do I model this camera mount - I've got so far but hit a brick wall

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  • Tim Heeney

    3D CAD used to be only done that way 3 decades ago. Generally it was called 'wireframe' geometry. We still obviously have wireframe geometry but it mostly confined to making surfaces with particular geometric properties - it a slow way to model.

    The lines you have drawn in 3D space are construction lines ( as you know), with a complete region selected to 'fill', they do 'fill' but they still remain in a 'curves folder' they can be used again.

    Have you found the Blend tool - you can blend between two lines ( Ruled surface), planar, cylindrical and conic surfaces can be made this way Or blend between a curve and a point eg a circle and a point to make a cone.

    It's important to know that unless all the surfaces match 'perfectly' together, after all this hard work etc, the software will not make a 'solid' and thus no 3D printing can be done - ouch!

     

    So, lets work with solids as much as possible for speed and automatic accuracy.

    How to make your part:

    Generally for the shape of that camera mount, i'd be making simple Solids and adding / subtracting them into more complex forms.

    The thinning out to suit molding process in the underside, is far more complex than the exterior shape - what exactly do you need here - an exact copy? I'm going to ignore it for the moment - besides, you mention changing it to suit magnets.

    In this instance the design is done, so you don't need to think how a design is concieved / created / developed  - only how to copy the design in the most efficient manner - there's a very large important difference here...

    Try this...

     

     

     

     

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  • John Lintern

    Many thanks Tim for taking the time to reply with a detailed explanation :)

    I will give your suggestion a try.

    Regarding the thinning out to suit molding process in the underside, I do not need this detail as I plan to make it solid except for cut outs to fit neodymium ring magnets.

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  • John Lintern

    Getting there - although did it differently to your method as I got confused !

     

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  • Tim Heeney

    Good - you're welcome to ask what / how next etc. also, there's masses of youtube on DSM / Spaceclaim and also, RS themselves have posted 'Getting started using DSM' video turorials...

    link for the 'introduction' only...Sketching, pulling, moving etc all follow on.

    https://www.youtube.com/watch?v=XyuzbKSCO90

     

     

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  • John Lintern

    Thanks Tim

    I've taught myself to use DSM using online guides, help and videos etc and made several projects (see below) but this camera mount was far more trickier.

    I've made further progress and should be ok to complete the rest, but once I have modelled the mount I will need to make a frame that surrounds the bottom of the which Im not sure how I will do yet.  I was thinking of using the mount as a 'stamp' to make a cut out from a solid shape.

     

     

    Boiler cupboard shelving:

     

    TV cabinet:

     

    Kitchen cupboard:

     

    Ladder storage:

     

    Electronics assembly:

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  • Tim Heeney

    I was about to say, as you're getting the hang of modeling / pulling / moving faces etc, now is the time to think about those magnets, where and how to fit them in...

    WRT, those other projects, all have good structure architecture : parts ( plus other bits) in Containers and Container/Parts / bits in Assemblies. At this level, you must have a good understanding of DSM.

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  • John Lintern

    The previous designs I've done were much simpler than what I am trying to do now.

    I have managed to model the mount so thats the first step, but now Im struggling with the next steps.

    This is the mount...

     

    This is the surround that goes around the mount (to stop the mount sliding around)...

     

    The mount with screws and ring magnets...

     

    The idea is that the surround will be fixed (to a helmet) and the mount and magnets will detach from the helmet...

    What I need to do next is modify the mount so that it encompasses the magnets, but thats where I'm struggling again.

    From the side view of the mount you can see where the holes for the screws go, so this space must not be filled...

     

    This is how the bottom of the mount looks...

     

     

    I want the underside of the mount to be solidified with space to fit and hold the magnets, like this sort of thing...

     

     

    But the fill must not block the space for the screws and the clips on the side...

     

     

    The latest design file can be downloaded from here...

    https://freeflyer.dynu.net/nextcloud/s/iLsfakjDefKYApm

    Any ideas how to do these next steps ?

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  • Tim Heeney

    Hmm, well as you're going to 3D print this part, lets forget about the existing part hollowing out all together - you have drawn slots for the end clamp screws, these are open from the underside but don't need to be with printing - fairly sure you know this as you discuss 'filling' it all in etc.

    I think you needed to start off with some sketches of a basic layout first. still with the flexibility of DSM / Spaceclaim nothing can't be quickly modified.

    I'd be looking to mount the magnets very slightly positionally compliant to ensure best possible contact with the helmet, therefore they can't be solidly held with zero degrees of freedom - this isn't necessarily difficult at all though. Sufficient rigidity between magnet and it's mount is important to support 'securely' whatever the mount carries.

    A constraint is the 2 long retaining screws - i guess they need to be as they are. However. the Vee volume probably isn't of much benefit for a magnet recess anyway.

    So the magnets( going by what you've shown ) needs to sit over the screws - think about raising the mount height to accomondate the magnet and a retaining plate ( of sorts) height.

    If you agree about the magnet attitude compliance ( you may not), at least with 3d printing, almost any flexure / plate spring shape is possible - and that's intriguing...

    Perhaps though, it's best to go with a 'simple design' ( no compliance) before imagining and solving a possible problem...

     

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  • John Lintern

    Thanks Tim

    I think I've finished it now and ready to get it printed.

    Link to 3D PDF...

    https://freeflyer.dynu.net/nextcloud/s/MiYqQcXJTcbyHPg 

    I've never had anything 3D printed before so any recommendations would be appreciated.

    At work they have a LulzBot TAZ and LulzBot Mini (pictures below), but I was told they are not very good and I wont be back in the office for some time (working from home) so I don't know when I will get a chance to try it.

    I've been looking at online printing services but they aren't cheap and I have no idea what material to use.

    I could do with a cheap prototype first to make sure it all fits together and works, if it does then Ill be more willing to pay more for a decent quality print.

     


     

     

     

     

     

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  • Tim Heeney

    Hi John.

    Material wise you'd be safe with ABS.

    However, i have to comment about what you have done on a safety aspect.

    The magnet holding principle was i assumed done to a) take on/off for convenience, b) to allow a frangable link ( break off on impact) to anything it held, thus reducing possible forces on your neck in a falling event.

    For both aspects, but constraining remarks to the 'b' comment, the surround doesn't need such high and parallel sides - as shown, the mount will only come away from the surround in one direction only !

    I've had nothing rapid prototyped in the last 25 years - lol...my knowledge isn't current...however, anything thin, not thick in the Z dir, always costs LESS - especially true with additive manufacture principles.

    'Think' before rushing to prototype - the bit you're doing 'now' is the easiest to alter at the lowest cost from the instant you press 'GO' !

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  • John Lintern

    I was about to add a taper to the magnet holder (blue) and surround (green) to allow for the camera to come away more easily.

    Reducing the height of the mount like you suggested is a good idea.  Unfortunately I struggled with the taper, it worked on some faces but then messed up on other faces.

    So I have reduced the height and stretched the base of the mount to increase its surface area for adhesion to the helmet.

    The reason for using the magnet holding principle is for the camera to come off the helmet in an emergency.  The mount will be used for skydiving and there is a (small) risk of the camera becoming entangled in the lines during deployment. 

    Usually helmets have a cut-away system where the user pulls a handle to allow the helmet to come away.  There are also cut-away systems where only the camera is disconnected from the helmet. 

    The cut-away system I have bought requires holes to be drilled into the helmet which voids its safety warranty and is not something Im keen to do on a £450 helmet !

    https://freefallgearstore.com/product/cut-mount-g4-cutaway-system/ 

    There is a magnetic system I know of which uses the same principle as my design, but the camera is mounted on the chin of the helmet...  

    https://vmag.dk/ 

    But this costs £115 and I think it will make looking down to see the emergency handles difficult (main canopy cut-away and reserve canopy) which are located on the front of the harness around chest area.

    I already have the neodymium (rare earth) ring magnets which are very strong.  I contacted a few suppliers of these magnets to see if they could make a custom shape magnet (curved) but this would be extremely difficult and expensive.  One of the suppliers rang me with some useful advice.  I had planned on fitting magnets inside the helmet for the magnets in the mount to attract to, but this supplier said the pull force would be the same if I just used an 8mm steel plate inside the helmet.  He said its a common mis-conception that two attracting magnets has a higher pull force than a magnet and steel.  Having tried this myself I'm still not convinced.

    So I don't know what the pull force would be for my design, it might be too much or not enough.  A steel plate would be safer than fitting the same ring magnets in the helmet as these would have to be cut into the protective foam lining and I expect this would make the helmet unsafe.  I also don't know the thickness of the helmet (made from ABS) and the gap between the magnets in the mount and the steel plate in the helmet wont be uniform as the magnet faces are flat.  I also don't know how I will make the steel plate, ideally it will need to be curved to the face of the helmet.

    With all these unknowns, I would like to test it before having a quality 3D print made.

     

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  • John Lintern

     

    Cross section of magnets with steel plate - I think the 8mm steel plate will be a safety issue !!!!

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  • Tim Heeney

    Hi John.

    I've been out today or i would have come bach to you sooner.

    Cross sections are an extremely good way to think about a design.

    It's seems to me a little nuts to go adding anything solid like a steel plate inside your helmet.

    Something else, I've always thought that magnetic force drops off inversly proportional to the square of the distance it's attracted to. So if any part of the magnet is twice the distance away than another part of it, the furthest way bit, only has 1/4 the magnetic attraction.

    Also, are you really sure of the helmet curvature? You could draw out some curves, paste to cardboard, cut and check the template...that's old school but simple enough.

    it is my view, that I'd be tempted to add a flat steel plate ( zick plated) around 10 swg ( ~3mm), not inside the helmet but instead, inside the surround. The mount underside could the also then be flat - that way you can assess exactly the magnet attraction force establishing size and optimum locations  - also ( if necessary ?) the steel plate could cheaply be thickened or thinned, again establishing a optimum hold to weight ratio. All of this can be done without any 3D printing and would give you very good confidence to proceed. The mount must come away from surround cleanly - consider taper all around.

    To reduce air buffering and shield pressured air from the magnet / plate interface, i'd attempt the mount to overlap the surround top surface - and all in a neat and tidy stylish way ;) ...

    Does a strong magnet affect recording quality ? - again something to know cheaply without a prototype.

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  • Tim Heeney

    John - you could also junk the surround - just epoxy the plate to the helmet direct - sure, the plate would need an initial levelling with an adhesive in-fill all around ( could be messy if not careful), and mount orientation / position done with 2 STEEP taper pins into two holes ( rounded at top ) in the plate.

    Just an idea to reduce another part - the surround had grown and might have been the highest cost to make plus, in using an epoxy in-fill, now no accuracy required to match any surfaces with the helmet shape.

    Apologise in advance for my ideas - offered all in good-faith that i'm helping. Let me know if i'm not .

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  • John Lintern

    Tim, many thanks for your input your ideas are much appreciated and useful :)

    I like the idea of having the 3mm steel plate in the surround so Im currently working on that.  I've done a quick knock up to see how it would look (steel plate shown in orange in the cross section below).  Using this method also allows the magnets to be flush with the steel plate with no air gap...

     

    I've contacted the guy at work who uses the 3D printers and he is happy to print these parts for me, he will use his printer at home as its better quality.  So this will allow me to test the parts fit and work correctly

    I think the surround is a necessity - the magnet supplier I spoke to said that without a surround the mount would move around the helmet.  The pull force is strongest when pulling away from the steel plate, but sidewards movement will be much weaker.  So without the surround the mount will easily slide around the helmet and possibly come off in freefall or if knocked. 

    Im fairly confident the I've got the curvature of the helmet correct because I've modelled the existing GoPro mount.  I printed the cross section in both X and Y planes and checked it with the GoPro mount and it looks very close.

    I would prefer to use 3M double sided pads to stick the device to the helmet rather than epoxy glue as Im trying to avoid damage to the helmet when the mount is removed.  Double sided pads would also help take up an compliance.

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  • Tim Heeney

    Hi John

    Your design is evolving nicely. The plate could have internal orientation features or the mount could extend over the plate sides,

    but hey, it's your design and with a mate producing very cheap parts , go for what you like / want i say.

    Designing in DSM is alot of fun eh!

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  • John Lintern

    Thanks Tim

    So this is what I've come up with...

    Cross section view with 3mm steel plate (cyan coloured) and I also managed to do the tapers on the magnet holder and surround (9 degree angle)...

     

     

    3D view...

     

    Assembly view...

     

     

    One concern I have is the additional height of the original mount from the helmet, it will be almost 24mm higher and the original height was bad enough and often meant the camera hit the roof of the (small) aircraft...

     

    The only way to reduce the height is to use smaller height magnets (the ones Ive used are 10mm in height) but as I don't know what the pull strength will be I will have to test this first.

    I suppose I could file down the (blue) surround and fit smaller height magnets to test this ?  Its easier to remove material than to add !

     

    Link to 3D PDF is here...

    https://freeflyer.dynu.net/nextcloud/s/MiYqQcXJTcbyHPg 

    I've used DSM for personal projects and at work over the last 6 years and its been very useful and Ive had great success with it.  I know its a cut down version of Spaceclaim, just as DS PCB is a cut down version of Easy PC (I'e used both those PCB tools)

    I've learnt some new, useful skills with this camera mount project with it being a more complicated shape too

    Having not used any other 3D modelling tools (only AutoCAD 2D) I sometimes wonder whether I could transfer my skills to use professional tools like Solidworks, Catia, Pro-E etc but I don't know how similar they are to DSM.  Not that I could afford to buy a tool like that and for the work I do DSM seems to be capable, although not being able to edit or export STEP files is a limitation.

     

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  • John Lintern

    Not sure whether to make the external faces of the surround slope like this to remove some of the 'bulkiness' (purely for cosmetic reasons)...

     

     

     

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  • Tim Heeney

    Hi John.

    Not deliberately setting out to vex you...

    Perhaps the blue and grey part could be one.

    If you knew the magnetic attraction, or did a simple test, perhaps 4 smaller height magnets could be used but not

    underneath the long screws, alternatively 'outboard' somewhere adjacent / located the sides of the clamping arms ( black parts) thus compacting the height - also, further apart, less retaining force is necessary. The grey part has to have a Vee , two screw pockets for screws and two tapered recesses for the clamping arms - all else is your choice.

    If you had 4 smaller magnets at the edges, then the metal plate could have a big round hole allowing closer proximity to the helmet and a thinner surround. - just a thought... vexing wasn't intended.

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  • John Lintern

    Not at all Tim your comments and suggestions are very welcome as is any constructive criticism (I am a perfectionist myself!).

    I like your idea of modifying the existing mount and using smaller magents so I’m working on that right now and will update for comment when done.

    I wasn’t too keen on the height and bulkiness of my previous design so it will be good to improve this.

    The only thing is I’ve spent a lot of time on it and getting a bit fedup with it, I just want it finished now and still don’t know if it will work until I come to test it. But I may as well get it right to start with so hopefully this will be the last revision before I can get it printed for testing. I’ll also have to order new magnets.

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  • John Lintern

    So the new design is 15 mm higher than the original mount - the new mount is on the left and the original is on the right...

     

    Magnets are 30mm x 10mm x 5mm t(8.1kg pull force)...

    https://www.first4magnets.com/rectangular-c35/30-x-10-x-5mm-thick-n42-neodymium-magnet-8-1kg-pull-p3690#ps_0_3850|ps_1_1928 

     

     

    Space for up to 6 magnets, if the pull force is too much I can remove magnets...

     

    Surround with 3mm steel plate and a further 3mm tapered wall...

     

    Cross section to first magnet at the side...

    Front view of mount...

     

     

     

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  • Jacant

    I have been enjoying the conversation between you two.

    The last design looks a lot less cumbersome.

    Why does the camera have to go on the top of the helmet? Can it not go on the front or the side?

    You say that on one part you would like to use 'Double sided tabs' is this to attach the mount to the helmet and use magnets to attach the camera. What are the 'bolts' in the mount for? Have you thought about 'Velcro'?

    As for 3D printing. I went to my local 'Makerspace', for the first thing I ever got printed. There may be one close to you.

     I was trained on AutoCad many years ago. This software is the easiest and the best.

     

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  • John Lintern

    Thanks Jacant, I thought Tim was the only person reading this post !

    The camera could go anywhere on the helmet but I've based it on the original mount I have which fits to the top of the helmet, this is a common place to mount video and stills cameras for skydiving.

    Before GoPro cameras came about, we used digital cameras (that recorded onto a small cassette tape) and these were bigger so were mounted on the side of the helmet.  There is one downside to side mounted cameras though, which is that the camera can bit hit by the canopy 'risers' during deployment.  The 'risers' are a similar material to seatbelts and connect between the rig harness and the canopy lines.  I've had many riser strikes when I had a side mounted camera (Sony PC105), you are advised to put your chin on your chest during deployment to minimise the risk of riser strike.

    The screws are used to fix another part to the mount which the GoPro camera attaches to and also allows the angle of the camera to be adjusted...

    https://www.flycookie.com/shop/g3/g3-roller-mount/ 

    GoPro's typically come with 3M adhesive pads to attach the various mounts which are strong... 

     

    But this adhesive is too strong to come off in the event of a line entanglement, hence the reason for using magnets which will allow me to control the pull force and it will remain constant over time.

    I will use 3M adhesive pads to mount the surround to the helmet, velcro is not as strong and weakens as it is removed and re-attached.

    The 3D PDF of my latest design is here...

    https://freeflyer.dynu.net/nextcloud/s/MiYqQcXJTcbyHPg 

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  • John Lintern

    Cross-section centre line front view...

     

    Cross-section centre line side view...

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  • John Lintern

    The only other question is how to fix the magnets to the mount - I was thinking super glue or something like that.  

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  • Tim Heeney

    Hi John.

    I think you may only need two of these magnets - one at each end - although maybe 3 of 4 as well.

    I see your 'positional' centralising idea and the encompassing matching of sectional wall thicknesses over width and length. I'm just wondering about magnets side to side possible magnet interference and i'm wondering about the the very small walls...I'm always used epoxy , admittedly i have little knowledge of 'Super Glues'.

    With epoxy you would need to ensure the excess ( and air to) can be pushed into an open void allowing proper location of all 6 magnet faces on a single flat plane.

    For styling i wonder if you might like the image below. - It's a ruled surface instead of a conic across the mount front /back.

    It's looking quite good John.

    But just another thought, the camera /mount coming off is a necessary safety precaution but losing a custom 'GoPro' - isn't that a definite no-no !

     

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  • John Lintern

    Thanks Tim

    You might be right about the quantity of magnets required but I will only know for sure when I test it.  I don't have specific a requirement for the pull force so it will be a matter of trial and error.  I can easily remove magnets if 6 are too much.

    When you say you are wondering about the very small walls, are you referring to the 3mm dimension I've circled in the picture below...

     

    As the first print will be a (free) prototype from my work colleague I just want to test it first to make sure it fits and works, I can then tweak the design when I get the better quality printed parts.

    Not sure which part you are referring to when losing a custom 'GoPro' being a definite no-no ?  

    If you are referring to the 'cyan' coloured part (holding the magnets and the camera) then this and the GoPro camera will be lost, but in a life and death situation this becomes irrelevant.

    The 'green' coloured part (surround) will be adhered to the helmet with 3M pads so this will not be lost.

    Another requirement is that my parts don't create a 'snag' hazard for lines to get caught on.

    Any idea's where I can get a 3mm steel zinc plate from ?  Common hardware stores don't sell it so I guess I'll have to order online, I only need a small piece !

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  • Tim Heeney

    No John, not that 3mm ( can't 'see' what that refers to ). i meant the 5 thin walls between the 6 magnets.

    OK - in 'Life or death' situation, one has to jettison all and be thankful...

    This place, of ebay i've bought from before. They might be able to offer custom sizes - contact them.

    If they can't then you'll have to bandsaw / jigsaw and file.

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  • Tim Heeney

    Wouldn't a round~ish bowl cover, with a tiny aperture ( for GoPro lens ), going over the top of the whole 'kit and kaboodle ' offer a significantly reduced ' snag' hazard ?

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  • John Lintern

    Ah ok, thats an optical illusion. I have left a 0.2mm gap between the magnets but there are no thin walls between them...

     

    I've just ordered 100mm x 100mm x 3mm galvanised steel plate from ebay and also the magnets.

    As for jettisoning all, at least its only the camera and mount.  With some other cut-away systems you have to jettison the helmet and everything attached to it (including an audible altimeter in an ear pocket in the liner which costs £200+)

    Its an unlikely event having to do this, but if its your reserve canopy thats entangled with the camera then loosing any equipment out weighs saving your life

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