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3D Printed board parts


Pari

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During this COVID lock down and losing employment because of it I decide I liked being home and it was time to start my own business. I bought a 3D printer to help with design projects- prototypes etc.

It’s been fun trying stuff out, and I’m going to see if I can rebuild my old Revo truck board using printed parts.

I’ve designed the main truck housing to use tradition skate truck hole setup as the original Revos have a specific setup which means drilling into your board.

I’ve printed this first test setup with PETG, which it the same plastic used in plastic drink bottles. So I’m hoping they will be less prone to shatter and may have a little flex. 
I also printed the bushings using TPU filament, not an easy thing to get right, damn stuff just wants to keep clogging up the extruder. But I managed to get two pairs done and they are a perfect fit, if a little stiffer than I want at shore 30D.

I’m no plastics expert, so I don’t know what to expect when I try them out. The wheels may break as soon as I start kiting, the truck housing could just shatter on my first turn- no idea.

But I’ve got new tires and tubes, will re- laminate my favourite board, probably treat myself to some new bindings and see if I can make it work.

7A7A564C-A3F9-4017-916F-AA20F0F602C4.jpeg

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Pari that's absolutely brilliant, thanks for sharing :good:  
 

12 hours ago, Pari said:

I’m no plastics expert, so I don’t know what to expect when I try them out. The wheels may break as soon as I start kiting, the truck housing could just shatter on my first turn- no idea.

Give @SoutherlyBuster a poke perhaps, stress analysis is right up his alley :) 

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  • .Joel featured this topic

Someone mention my name .... sniff sniff .... .

 

Hi Pari,

Sorry you lost your job, quite a lot of us got shafted recently. Unstable times. Joel is right, stress analysis is my professional speciality. There are methods and software tools to predict and design for stress, there are however some perhaps uncomfortable truths. So you have the geometry and material — good start. To predict the stress response (will it break), you need to know:

1) material stiffness, if it is composite, stiffness in various directions and the interaction of them.

2) material strength

3) load inputs.

So you head off to your material supplier and ask them about items 1 and 2. Odds are they do not have a clue or critical parts are missing. Google may help, but do you trust it, is it the same material, is the manufacturing recipe the same?  So you need to build your own coupon specimens, subject them to a known load, measure how much the deflection  is (the elasticity), measure when it starts to degrade strength wise (limit loads), measure when it finally breaks (ultimate loads). Now you can feed this material model into your analysis.

Next you need to figure out the load inputs. Hm which came first the chicken or the egg? You can have a guess of what the loads might be based on a use case — inputs for your first prototype. Prototype built, put on some load cells and or strain gauges on it to measure the real inservice loads. Feed that back into your model, now you can evaluate where all the weak points are, redesign, re analyse without needing build and physical test during this iteration stage. Then a final physical test, to check all your assumptions and the things you did not think about. There are methods to figure out the input loads from theory alone, much more complex.

Ever wondered why carbon fibre parts are so darned expensive? No standardisation of manufacturing methods and material strength, all has to be tested in house, not to mention the complexity of the material it’s self. Metals a different story, take for example the MMPDS or MIL Standard book, manufactures are told what the strength must be, they need to prove that it is actually that strong. Still physical testing at some stage is necessary.

A hybrid approach may be taken, you have a prototype, have an idea where the main load comes from, know the material strength. Take the part out in the field and abuse the hell out of it and see where it breaks, feed that back into the detailed model to reverse engineer the input loads, now you can change the design and see what effect it has.

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Hey that's really cool. For safety and just to know. You may want to inflate a tire to failure. See how much it can safely hold because when plastic wheels let go it; it's typically catastrophic due to the flying pieces. I'm interested in knowing how much pressure they can handle.  You may be able to add some material thickness to get them to take the pressure if they initially can't. 
 

Also on the trucks consider running metal straps from one side to the other on the bolts for extra strength if the material needs it or thickening it up if it proves to need it. 

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On 9/11/2020 at 9:47 AM, Pari said:

During this COVID lock down and losing employment because of it I decide I liked being home and it was time to start my own business. I bought a 3D printer to help with design projects- prototypes etc.

It’s been fun trying stuff out, and I’m going to see if I can rebuild my old Revo truck board using printed parts.

I’ve designed the main truck housing to use tradition skate truck hole setup as the original Revos have a specific setup which means drilling into your board.

I’ve printed this first test setup with PETG, which it the same plastic used in plastic drink bottles. So I’m hoping they will be less prone to shatter and may have a little flex. 
I also printed the bushings using TPU filament, not an easy thing to get right, damn stuff just wants to keep clogging up the extruder. But I managed to get two pairs done and they are a perfect fit, if a little stiffer than I want at shore 30D.

I’m no plastics expert, so I don’t know what to expect when I try them out. The wheels may break as soon as I start kiting, the truck housing could just shatter on my first turn- no idea.

But I’ve got new tires and tubes, will re- laminate my favourite board, probably treat myself to some new bindings and see if I can make it work.

7A7A564C-A3F9-4017-916F-AA20F0F602C4.jpeg

Hey @Pari, they look really good. Make me think of a 3D printed Glock 9mm - should work well for a while :blackeye:

I think you're fine with printing the elastomers but what happened with the CNC'd ally rims you were working on? Those really looked the bomb! Couldn't you mill the truck housings as well?

 

7 hours ago, SoutherlyBuster said:

Someone mention my name .... sniff sniff .... .

 

Hi Pari,

Sorry you lost your job, quite a lot of us got shafted recently. Unstable times. Joel is right, stress analysis is my professional speciality. There are methods and software tools to predict and design for stress, there are however some perhaps uncomfortable truths. So you have the geometry and material — good start. To predict the stress response (will it break), you need to know:

1) material stiffness, if it is composite, stiffness in various directions and the interaction of them.

2) material strength

3) load inputs.

So you head off to your material supplier and ask them about items 1 and 2. Odds are they do not have a clue or critical parts are missing. Google may help, but do you trust it, is it the same material, is the manufacturing recipe the same?  So you need to build your own coupon specimens, subject them to a known load, measure how much the deflection  is (the elasticity), measure when it starts to degrade strength wise (limit loads), measure when it finally breaks (ultimate loads). Now you can feed this material model into your analysis.

Next you need to figure out the load inputs. Hm which came first the chicken or the egg? You can have a guess of what the loads might be based on a use case — inputs for your first prototype. Prototype built, put on some load cells and or strain gauges on it to measure the real inservice loads. Feed that back into your model, now you can evaluate where all the weak points are, redesign, re analyse without needing build and physical test during this iteration stage. Then a final physical test, to check all your assumptions and the things you did not think about. There are methods to figure out the input loads from theory alone, much more complex.

Ever wondered why carbon fibre parts are so darned expensive? No standardisation of manufacturing methods and material strength, all has to be tested in house, not to mention the complexity of the material it’s self. Metals a different story, take for example the MMPDS or MIL Standard book, manufactures are told what the strength must be, they need to prove that it is actually that strong. Still physical testing at some stage is necessary.

A hybrid approach may be taken, you have a prototype, have an idea where the main load comes from, know the material strength. Take the part out in the field and abuse the hell out of it and see where it breaks, feed that back into the detailed model to reverse engineer the input loads, now you can change the design and see what effect it has.

Or just go "old school" - put them together, pump up the tyres and give it a berl. We lost a few along the way but we did end up with an aviation industry. No?:crazypilot:

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On 9/12/2020 at 1:47 PM, Mfwetu said:

Hey @Pari, they look really good. Make me think of a 3D printed Glock 9mm - should work well for a while :blackeye:

I think you're fine with printing the elastomers but what happened with the CNC'd ally rims you were working on? Those really looked the bomb! Couldn't you mill the truck housings as well?

 

Or just go "old school" - put them together, pump up the tyres and give it a berl. We lost a few along the way but we did end up with an aviation industry. No?:crazypilot:

Yeah, "old School" test pilot is more my thing. I got a nose bleed just reading the stress analysis procedure. There is info on line, one guy in particular, who has a YouTube channel called CNC kitchen, his approach is all stress analysis and various material properties etc. of 3D printed parts.

But I spent last night putting together my current board, the crap one I've been using for the last couple of years since my Revo elastomers failed and I went to my skate trucks board. I cleaned it all up, put the new tires and tubes on, and put the two prototypes of the printed wheels on. When I blowing the tires up at the garage the inflator went up to 18psi and then back down to the desired 7psi- so far so good, nothing popped!

Then I took the board to the beach today desperate enough to try and kite in what must have been about 7 knots. I got about 50 meters of kiting in then gave up, not enough wind to keep going, but a win all the same, no cracks so far, looking good.

As for the previous alloy wheel project from a few years ago- I always intended to make a full set, even have the Carbon Fiber tube for the middle. But I sold the little machine I did that first couple on and haven't really felt that this new machine would be any good for alloy- It's a good machine for wood which is what I do lots of, but I had to cut some 'T' slot on it recently and the finish was crap, to much slop I guess in the gantry.

The beauty with the 3D printer is it's just so damn easy, were as milling is messy and takes a lot of working out of the tool paths, two sided machining which means jigs blah blah. The printer- do the CAD, export the file to a SD card, put it in the printer, load the spool, hit go and come back in a few hours. I love it, no mess, no noise, no waste.

Plus it's a new toy, so I'm like "what can I make with this thing".

I will be cutting alloy sides for the 3D printed Revo housings and the strap/washers were they are bolted to the board (yes, I had the same idea- great minds and all that), but they are just simple profile cuts and a bit of drill so the edge finish can be cleaned up if it's shitty. I also got my hands on the nylon needed to cut the slider parts the axle is guided through.

It might be while before I get back to this thread with the Revo board all updated so apologies - I'm at the start of my new business and this is a fun project but no a priority.

 

Wheel printed.JPG

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UPDATE:

I got a half decent session in this morning, about 10 knots and a beautiful large flat area to kite, with the tide out, down the bottom end of Kingscliff. Twenty minutes kiting with jumps and power slides. The last power slide smashed the rim off.

Interestingly this is the rim that I had previously broken by bouncing it of the concrete floor just to see what would happen- of course it broke a bit of the rim off, DOH! I hid this on the inside of the tire. When I looked at the break and the pieces I can see it broke across there because I sanded the sharp break and there is a distinct line across the the middle of that sanded area. Also I'd forgotten that I'd printed these both with only 20% infill, meaning there is a couple of perimeters and a criss cross lattice of only one extruded width of the filament. With the Revo trucks they are 100% infill, solid pieces of plastic. So I think a re-print of these wheels with 100% infill and avoid bouncing them of the concrete might do the trick. I think it's a Cyber Truck Syndrome thing- hitting it with a sledge hammer then wondering why the bloody glass breaks!

wheel printed break.JPG

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  • .Joel unfeatured this topic

Another UPDATE:

I re-did the CAD for the wheel based on what I saw from the break on the first test run and Looking at a cross section on the screen. The chamfer on the rim inside the spokes was making the rim area quite thin, so gone are the chamfers, and I added more thickness to the rim wall and printed with 100% infill.

I did get to machine my alloy parts for the trucks, and the trucks put together look sick, I’m very happy. 
I dug out my alloy rims from a project I started years ago and am in contact with an anodising place to see how much it’ll cost to get everything anodised. If it’s going to cost a lot I’ll probably just put a clear coat on them to help prevent corrosion from the sea.

Now for some more test runs.

 

45AF456C-04BE-49AD-AC54-3BB5C0A7FD34.jpeg

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2 hours ago, bakersdozen said:

Looking super tasty !

I think from memory @plummetused a cut down cv axle boot cover on his to keep the sand out of the bearings - as you know the originals had a smooth cover. 

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I did think about it, print them with the same TPU filament as the bushings and the model would be a very easy shape to print- ideal really as they are a nice gentle taper upwards with no undercuts or over hangs. But I road my original Revos for a long time with totally split and falling apart boots. I think with the bushings being pressed so tight against the nylon guides, I’m not to concerned about it- time will tell.

I went out this morning, the new wheel lasted a proper session and I think I’ll re-print the other side the same way.

 

ED894757-397E-4139-9F06-F4DBC43AEFF6.jpeg

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2 hours ago, bakersdozen said:

Great! Keen to see how your printed trucks perform next 😁

I just put one of them on the board and stood on it and leaned as if to turn and all looks good, seems to turn as much as the skate truck that’s still on there. No creaking! Will do a test run with the one on there then if all goes well will fit the other one on.

just curious, what trucks are you using?

412D3B27-FCED-4553-9FA7-C96E97B7E4A2.jpeg

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56 minutes ago, Pari said:

just curious, what trucks are you using?

Excellent that sounds very promising, dude. 

I'm not entirely sure the model of Revo trucks I'm running but they're not the P shape mount ones. I've got them inverted to lower my board centre of gravity. 

large.DSC_0464.jpg.0bbcaf0054b40082a8a25

large.DSC_0463.jpg.f59ca9668cd4d1c04bfff

large.58a96bbc8f29a_Mezphotedited.jpg.42

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3 hours ago, bakersdozen said:

Excellent that sounds very promising, dude. 

I'm not entirely sure the model of Revo trucks I'm running but they're not the P shape mount ones. I've got them inverted to lower my board centre of gravity. 

large.DSC_0464.jpg.0bbcaf0054b40082a8a25

large.DSC_0463.jpg.f59ca9668cd4d1c04bfff

large.58a96bbc8f29a_Mezphotedited.jpg.42

They look cool with the carbon housings. Are they a custom made set?

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they look great , a DX type axle , i have one of the last DX's and they are a very smooth ride and low , how are you getting on with it ?mine are alloy housing with titanium axles carbon deck carbon footstrap brackets - i always use heavy webbing for foot straps , much lighter than anything else 

sorry to be a bit negitive but i wouldn't want to run my revo trucks on the top, they must take  a hell of a slamming if you are jumping 

how is the first board going with your orange trucks 

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7 hours ago, Pari said:

They look cool with the carbon housings. Are they a custom made set?

No, they are an original DX set, I bought from a kitecrowd member years ago. The carbon is just a wrap around the edges - bling only.

 

3 hours ago, slide said:

sorry to be a bit negitive but i wouldn't want to run my revo trucks on the top, they must take  a hell of a slamming if you are jumping 

I've had no issues in the many years I've been running them this way. They're gonna get slammed either way they are oriented If that's how you ride. These axles are stainless and I had them made 100mm wider than the standard axles that came originally with the trucks.

Which reminds me I still have the original axles here not being utilised. Might have to do something about that soon after @Pari does some further tests 😉

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@bakersdozen What are the foot starps you have on there?

Part of the board build is to get some footstaps but I don't like the traditional MBS style ones with the metal brackets on each end. I have some big old Kitesurf ones, but they are really comfy and nice for hooking the toes under on sharp turns. Want something similar but lighter.

4 hours ago, slide said:

they look great , a DX type axle , i have one of the last DX's and they are a very smooth ride and low , how are you getting on with it ?mine are alloy housing with titanium axles carbon deck carbon footstrap brackets - i always use heavy webbing for foot straps , much lighter than anything else 

sorry to be a bit negitive but i wouldn't want to run my revo trucks on the top, they must take  a hell of a slamming if you are jumping 

how is the first board going with your orange trucks 

I'm a bit confused here, are the axles on Revos meant to be Titanium or is it just certain models? I'm pretty sure mine are stainless, at least that's what the machinist said when I had the ends re-done.

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18 minutes ago, Pari said:

@bakersdozen What are the foot starps you have on there?

They were just some generic foot straps I got from Munro boards ages ago - all velcro. I've since updated them to the new MBS F5 - heaps more comfortable as I prefer the MBS style. I'll have a look for them on the weekend and update some board photos too.

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Wahoo the Revos are BACK!!

I did a bit of a down winder and the printed Revo works really well. I'm so pleased. The difference between the skate trucks constant wobble and the smooth stability of the Revo was great to see.

I'm gonna get both trucks on there now, give them a proper test session or two and start to get this new board built.

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1 hour ago, Pari said:

Wahoo the Revos are BACK!!

I did a bit of a down winder and the printed Revo works really well. I'm so pleased. The difference between the skate trucks constant wobble and the smooth stability of the Revo was great to see.

I'm gonna get both trucks on there now, give them a proper test session or two and start to get this new board built.

Yesss! Nice one @Pari that is awesome news. I *might* be just as excited as you (if you can't already tell)

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39 minutes ago, bakersdozen said:

Yesss! Nice one @Pari that is awesome news. I *might* be just as excited as you (if you can't already tell)

Yeah, it's good, proof of concept. I found fitting it to the board, putting it together, everything much easier than my original Revos with the alloy body. I think I will tweak it and print some in different materials like ASA (which is what is starting to replace ABS in the printing community as it's less prone to warping and doesn't give of as many fumes).

But I think I will print another set in the black PETG when my parcel arrives with some new filaments.

 

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1 hour ago, bakersdozen said:

Awesome, I figured you would play around with a few materials now you have the means. I'd be glad to be a test guinepig for anything down the track. Be good to put these spare axles to use 😉

Sure, I'd like to get some of these out there. There must be some other Revo nuts out there who'd like to upgrade or repair an old classic. Bit early to say for sure but I could see myself doing some full upgrade kits- housings, alloy straps and sides and the bushings with all the hardware included- stainless nuts and bolts. 

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