Showroom 6DOF Motion Platform á la Knaufinator

Arms were made by layering 10,2,10mm laser cut sheets - this gives the 22mm width for the locking bush and maintains accuracy of the cut. It also meant I could put pockets in it:

The Ø45mm hole was aligned during welding with a locking bush. I also pre-heated the parts in the oven to 250°C to try an minimise warping.

Separate parts for the clevis were welded on:


Then they were welded up and ground smooth:

Finally, I carried out a trial fit before painting them:


The locking bushes are rated at 315Nm, which is well balanced with the final drive torque. Also, the keys sit slightly proud of the shaft surface, which gives the bush something to grip.

Once the arms were on it was time to test the wiring again!

Getting very close to the final stage of putting it all together now!

All of the electronics work, emergency stops function, startup and home routine works.


Wiring has been tidied up:


I hope to make a video of the build for your entertainment......!

do you own a laser cutter ? seeing these make me want to own one !!

Sadly not..... I was surprised at how low the cost was though. I used https://www.lasermaster.co.uk/ and they would typically turn an order around in a week, they also gave me some good advice on what sort of thicknesses cut well.
As an example of cost, that huge base plate was about £80 including material and was cut from 12mm steel. The parts welded onto it were typically around £5 each including material.

Here we are Folks. Switch-on and my first go with VR on No Limits 2. Apologies in advance for the unintentional swears - it's very immersive!!

I've since improved it with the filtering, which makes it much smoother, and there are already some changes to make to the design. The legs are too tall so it has plenty of authority for heave, roll and pitch but the aspect ratio means it has much less for surge, sway and yaw. Nothing a hacksaw and MIG welder can't sort

Anyway, massive thanks to @knaufinator for the inspiration, open sourcing and technical support. It's such a cool toy!

This is one of the nicest builds that I have seen. You clearly enjoy building as much (or more) than using the setup. Well done!

I just stumbled onto your build, good job!

I was notified of this thread, and I thought it was my own, as i saw my name in the URL.

I get a kick out of seeing my PCB being used, its pretty neat to see the open source project actually being enjoyed.

Nice work. Reducing the length of the legs will also stop allot of the secondary oscillations.

Thank you - yes, you got me there with the enjoyment of the build

Thanks - it's a very fun project but it's the quality of the open source elements that make it so awesome.
It's super-cool and my kids find it hilarious - congratulations on conceiving a very flexible and powerful system I'm also looking forward to seeing more of these designs out there in the wild.

Hello, I am Flying Onion. There's something wrong with my YouTube. I can't comment on it in your video. The project of knaufinantor is very good. I've started to do it too. I'm in trouble. Can you direct me? Can you please PM me, waiting for your reply

Hi @flyingonion - great name . Yes, I will do what I can to help you!

I prefer to solve problems on this thread because then it will be helpful for other people who are doing the same project

There are a some things that I did wrong in my project that took a lot of time to work out so it is good to ask for help when you get stuck.

What stage have you got to with your project? and what are the problems you have found?

Dirk, how much did your servos and gearboxes cost ?

I got these motors (the B.90 version): https://www.aliexpress.com/item/32844239563.html?spm=a2g0s.9042311.0.0.3da24c4dBfrlPB
And these gearboxes: 50 :1 Helical Gear Planetary Ratio 50 Reducer Gearbox 6000rpm 19mm for 90mm 750W 1KW AC Servo Motor Robot|Speed Reducers| - AliExpress

The motors were about 1,000GBP plus import duty of about 200GBP for the six and the gearboxes about the same. Total cost was about 2,500GBP for motors and gearboxes.

The price seems to fluctuate quite a bit and they're often on offer - they seem to be a lower price at the moment.

This is by far the biggest and scariest single cost in the project! I ordered 1 motor and 1 gearbox to start with. Once I had that that working through Simtools and Knaufinator's PCB design I had a bit more confidence to order the remaining 5.

Did the servo motors include the servo drivers ?

I have seen Knaufinators sim in action it has enough power to hurt you ! He has a built in accelerometer that can trim the force iirc

Thats a very good cost for 6x motors and gearboxes

Have you calculated how much weight it can lift ?

Yes, the servomotors include the servo drivers.

It has plenty of power but I think it needs it if you want it to have enough authority for the accelerations. E-stops are essential for something like this!!

Servomotor has 2.4Nm rated and 7.1Nm peak torque. With the 50:1 reduction, the torques go up to 120Nm and 355Nm respectively (minus losses due to gearbox efficiency). Each arm is 250mm long, so is capable of a peak force of 1420N or 144kg. Six arms gives a total of 8.5kN or 868kg force available. For a platform that weighs around 200kg with a person on, that gives a peak acceleration of about 4g. That can only be sustained for a very short time as it would quickly run out of available travel.

hello,I have purchased the servo motor.And has ordered PCB boards,He started out well,There is no problem in powering on,There is nothing wrong with Hall sensor.Axis test is also normal,That is, when connected to the game,He will twitch irregularly,He won't work with the game,I have checked the plug-in, and there is no problem. I don't know why.I have discussed this problem with his original author, but it has not been solved yet.I found that you are also working on this project, so I asked you for advice.