Wood 6DOF Platform (13 ply Laminated Birch)

[Stevant1]

Hi all,

I figured I would post pics of my platform as I progress. First and foremost, I'd like to thank Thanos for all his input and advice, for without I would not have known where to start. His blog has a host of information from which you can move forward with your own build. Looking forward to his continued support. I also want to thank Fabi for his pics that were posted on the blog. The dimensions on my platform were taken from the ones he provided. His platform has excellent movement. I'm a cabinet maker by trade so using wood was my first choice. I used 13 ply Baltic Plywood which is extremely straight and strong. I was visiting an amusement park and was studying the wooden rollercoaster designs which inspired me. Steel of course is an excellent choice but since I'm not a welder and don't have the tools to cut steel, the wood is a great option that when tied together and supported to each other, as you can see in my pics, results in absolutely no movement in the structure. It's rock solid. I'm just waiting on my motors, ball joints, shaft reducer for the positioner and the arms for the gearboxes.

I put my inverter cabinet in an upright position as stated in the manual with the requested spacing in between to avoid excess heat that will be generated. They also recommend a closed cabinet to keep dust and debris out of the inverters. Longevity is important since they are one of the larger costs for the project.

The upper platform is going to be made of steel. I'm going to use the one in the photo for testing then I'll bring to the fabricator for his template.

Let me know what you think so far. I'll post more for those interested and as I progress.


Sincerely,


Steve

[EstebanR]

Looks great, which motors did u use?

[Stevant1]

Ironhorse makes both the Gearbox (WG-262-060-D) which are in the photo, and the Motors (MTR-001-3BD18) which are on back order until 9/13. I should have them in two weeks I hope. They are 1 HP motors. They mate right up to the gearbox so it should be a quick install. I have the wires all laid out once they go in.

[DoctorD]

Hey Steve,

Glad to see you're building a 6DOF from thanos' blog as well. The AMC1280USB is a lovely bit of kit.
I'm currently doing a 6DOF build myself and will be really interested to see how your progress tracks. Please shoot me any questions if you need a hand with the mechanics (or anything really).

I'm thinking we'll be working on similar stages of our projects and could sure use as much comraderie as possible

Good luck and (as always) have fun building and designing

Sincerest regards,
DoctorD

P.S. what country are you in? (I'm from Australia)

[Stevant1]

Hey Doc,

I am from the USA. Nice to meet you. I appreciate the offer and would be happy to share my progress. Please do the same. I am really excited about this and trying to make sure it all comes out just perfect. I try and post as soon as I complete a step and appreciate any feedback. Thanos has been great and really extends himself. Seems like a great guy. Never knew there was a community so involved in this kind of stuff, it's great!

Once I get my board from Thanos I can really start to get the electronics portion of the project in motion. I know getting it all to work will be my challenge but from what I've seen thus far with others who have completed this design, it should be just fine. I'm hoping the wood structure really shines. Like I said in my earlier post, it is rock solid. I'm also building on a basement slab which also is a great support.

Looking forward to your progress and thanks for reaching out!

Sincerely,

Stevant

[Stevant1]

Just another update....

I wired up the motor side of the inverters, still waiting for the motors. The electrician came by today to see what will be needed to power up the inverters. We are going to run 6, 20amp circuits, one for each inverter. One step closer..........

[DoctorD]

I'm really digging the look of the timber Stevant1

Another thing you can look at for the frame might be to seal/impregnate the timber with epoxy resin. They do this with boat hulls to seal the outside for longevity, but it also has the lovely benefit of making it a s#%tload (technical term) stronger and stiffer.
The process pretty much involves mixing up a low viscosity batch of epoxy resin, painting it over the timber and then allowing it to penetrate into the material. When it hardens, you end up with a fully sealed surface with the outermost portion having undergone significant increases in tensile/compressive strength. This is a very low-tech way of replicating the new age composite panel approach.

Other than that, I really like the way you've attached the gearboxes at both the top and bottom. Very stiff and utilises a very deep section modulus. btw, if you want to make it even stiffer, you could add in a vertical member connecting the top and bottom transverse beams in the centre (to reduce the slenderness of both beams).

Looking really good

P.S. you could probably make the top platform out of timber if you wanted. If you double laminate the frame with ply and impregnate the assembly with epoxy it would be immensely strong (and light). I can help you with the design if you would like.

[Stevant1]

Thanks for the compliments Doc. My son and I were talking about that a few days ago. We were thinking about vertical supports once the motors come in. We think a like. The support is what we were looking for since we are going to use the upper support as a step to get up to the upper platform. The support will further solidify the structure and support the weight of us getting on and off.

As for using wood for the top platform, I could also wrap the frame with glass and resin. It will keep the look of the wood with the strength of the resin you were talking about. Hmmmmmm........all wood no metal.

I know the top is going to bare the brunt of the weight over a smaller surface area. I think I might go metal only for the fact that I would hate to redo if it starts to fail over time due to the stress of all the motions. I do like the idea of epoxying the lower platform, I guess I can head over to my local boat yard to see what I coud use. Can't beat a marine epoxy for the wood.

I'll take a picture of the platform I might be placing on the top platform. Might have to lighten it up but it looks real nice.

[DoctorD]

With regards to the upper platform, I really do think that there would be a way to incorporate the strength you require into a combination timber/steel-rod/ply/metal-bracket frame (without the use of glass fibres). That said, glass would add a considerable amount of strength, but it's main advantage comes from being able to increase the 'depth of section' relative to overall mass of an object. (which can be done with timber just the same)

If you simply have, say, 50mm rectangular timber framing, fully bound by 19mm ply (top and bottom), then you end up with almost a 90mm deep section. This would certainly be strong enough to withstand and transfer the loads of a moderate cockpit platform (especially if you construct the cockpit and surrounds using smart construction).

With respect to cockpit construction... I have had tremendous success using fibreglass over polystyrene cores in the past. I currently have a pair of 2m beams that weigh less that 6kg combined, that can take my full weight in the centre (without deflection) as I jump up and down on them. Extend that to a cockpit scenario and you end up with maybe a 30-40 kg complete 1:1 jet fighter/racing car cockpit that can fully support itself. Use bent alloy or fibreglass poles to drape black 0.2mm poly sheet over the top and you're still no-where near 50kg.

The only other issue you'd need to address would be the highly loaded contact points between the heim joint connection rods and the outer perimeter of the upper platform. If you make up some flat steel plates and drill holes just big enough to pass the connection rod through, you can really spread the shear forces out into the timber frame and ply (and also increase the frame strength at the same time).

I've added a quick sketch of what I'm getting at

Suggestion.jpg (79.78 KiB) Viewed 34319 times

[Stevant1]

I like the sketch and would take it a step further by wrapping the steel plate around the outside and inside angle tieing the adjacent sides together. I would run a bolt through the return on both sides if you can visualize without a drawing. If I did that on all three sides with the bolts, I believe the wood will be fine.

Thanks for the drawing. I will be adding the support for the threaded rod to carry through deeper into the middle of the platform.