6 DOF from scratch

No giving up, no giving up, no giving up... repeat.

I was sure that the 10 turns of the potentiometer would not cover the full traverse of the actuator. Now, I am not so sure it would not. I will take this in consideration for the next design. Still, I don't want to put stress over the pot shaft and still have a well bend strap. That is a nice design challenge.

I don't think I could use the screw holes on the motor for full support because they are really small. I would obtain tiny rod out of it. But, you gave me a great idea. It started by adding a back plate attached to the structure screwed also to the motor for more solidity. Then, why not attach another plate on the other side just the length of the motor? A box around the motor. The end of the actuator would now be strong, ready for almost any type of attachment, at a reasonable cost. I could attach fan on each side to ventilate the motor. I think I finally found the right way to go about it. Thanks for the inspiration.

500mm travel of the shaft, 2mm pitch belt and 40 tooth pulley yields almost 7 turns on the pot. You still have 3 turns extra.

Exactly, I'm using the pot directly attached and I don't have any problem, also, the pulley was lathed so it can fit over the pot screwable part to lower the lever force over the shaft. You have a 3d printer so you can do a custom part to lower the stress over the shaft.

I don't have the pulley with me, but from my picture and the one from @mariano68, I count about 10 tooth on one side. So I figure they are 20 tooth pulley. But, I don't have a full 500mm travel of the shaft. So, I should be fine.

The plan is make a part that support the pulley just before the fixing screw, and attache the pot on the other side.

So, here is the design. Most of the stress should be on the bolt and much less on the potentiometer.



It was not easy to fit it in, but with fortunate tools, I was able to build it up.



Then, fitted into the actuator. I did not bother much with the straps orientation and how far it could go.



I just wanted to see it work. I'm holding it up because nothing is glued and there was a lot of vibrations.



And I'm still having base configuration crisis.

Awesome design. It was exaclty was I was planning to do. However, now I want to test a quadrature encoder instead of the potentiometer.

carefull those blue potentiometers are %£¨%µ!
Mine did not like at all "high speed"

Don't worry @baykah , I already received my Vishay 536-1-1-103.

6 DOF from scratch

I use my blue one for my tests and design.

Ok, It's been a year since I started this build. So I did a little recap on everything I thrown into that thing on my first post. I put everything. The computer, the Vive, the 3d printer...

6 DOF from scratch

Well, almost everything. I left out a few tools that I wanted for a long time and used the build as a excuse to buy them. I also left out the Pimax headset that I should receive in a few months.

So far, I put 8519.45 into it. This is a bit scary. Do I regret? Not at all. The only regret I have is that it is not done yet.

I tried to put as much information as I could, for those who would like to jump into the adventure. Where did I get the parts and how much it cost. Of course, for more in depth information, read the threads.

I hope it will help.

Thanks for the update, very informative and I like that you've added this to the first post as it's where new members would usually start. But I think that you should remove the email addresses as it's not good practice to publish email addresses in forums as they can potential get slammed. Also some of the links you have provided link to your account and not the public item e.g. I was interested in the carbon tubes but the link takes me to alliexpress login prompt.
Keep up the good work, nearly there now! I've enjoyed following this thread and wish you the best of success.

I've removed all the e-mail address. I have corrected all the links to Aliexpress. I provided a link to all parts websites. If something was not available, I tried to give an alternative. It should be a lot more complete now.

Okay, just found out I could not connect two 12v psu in series without modifying one (cutting the DC ground from the AC ground). I found this tutorial that shows how to do it. I did not test it yet, I just don't want to lose the link.

http://fpvlab.com/forums/showthread.php?5450-DIY-12-24V-high-power-PS

Indeed, after cutting 2 jumper in one of the PSU, I could get 24v. Yeah!

Question! If someone is listening.
How do you guys set up a kill switch with PSU? I tried to use the back connections to kill the PSU. They work on individual PSU, but I cannot connect them in series or parallel to kill 2 or more PSU in one go.
How can it be done? Any ideas?

you would need to use a double pole switch so that you are physically switching two separate circuits. The lamp would be power supply 1 and the motor would be power supply 2, in this configuration they are still isolated so it will work. as for what connections would need to be made, you would have to figure that out in the pin out of your power supply.




more information on switches here

https://www.electronicshub.org/switches/

Most emergency stops already allow for switching two isolated circuits or additional contacts can be added to accomplish this.

Or if you are switching even more supplies (or additional equipment) you would move to relays and then a single switch could control an infinite amount of individual circuits. In my case everything is setup on relays and when I hit the e-stop it turns off all of the relays in turn killing everything that I deemed to be dangerous. This is more complicated because it requires an additional control circuit, but worth it in my opinion to have a single switch turn off everything.

Yeah, maybe I could have used a switch with multiple connectors to turn off my PSU, but I have 6 of them. Anyway, my first plan was bad from the start as they take 2 seconds to shut down. In a dangerous situation, 2 seconds is a long time.

So, like you said, I went the relay route. But I had not much idea how strong they needed to be. So I asked @SeatTime what he used. You can see the start of a great conversation here: SeatTimes 6DOF DC build Really, informative.

I'll be using six 70A relay driven by 12V. This 12V will be provided by another relay, driven by 5V. This 5V will pass by all the limit switches, the panic button and probably 3 other relays, each driven by my arduinos. This will ensure that every system are okay to go before powering the motors, and stop them if anythings triggers. At least, this is how I plan to do it. Waiting for the parts.

That’s pretty much how I am doing it, I shut down my power supplies with e-stop but I also have a 70a automotive relay that disconnects the 12v supply to the sabertooth so the power is removed instantly. This also separates my battery from the system so that the sabertooth doesn’t drain the battery over time.

If you take a look at my 2dof build you can see it in more detail.

Also your grounded supplies can all be switched on one circuit and the floating all on another so you should only need one switch. But if they take that long to shut down that’s not good. I am actually killing the ac on my power supplies so I’ll have to see how fast they shutdown.

Keep pushing forward.

That's good information. I will take a look at your thread for sure.
Thanks.
Pushing forward. Slowly but surely.

I will put the relay between the Sabertooth and the motor, like @SixDegreesOfFlight did (check his thread) and not before the Sabertooth. This provides a faster shutdown of the motors, but doubles the number of relays required.