Seat Harness Tensioner Questions

we cross fingers for you! it's really difficult to create and be innovative

soon a video hopefully

Will do, Matt! Cheers!

Got an update on the belt tensioner design. The all-plastic printed guides work OK but I was concerned about the drag of the belts in them creating too much friction and sapping away some of the belt tension. The friction would get worse the more pull there was too. In thinking about the problem, I came up with this.

I looked into some round bar and needle bearings to just make a wide pulley for the belts to roll over. I'm using 10 mm nominal diameter, 80 mm long metal shafting and 10 mm ID, 14 mm OD needle bearings in a printed housing to hang the bar a bit over the side of the mounting to give a more free path. The bearings and bars snap in and the strap holds the belt captive. I'm modding the design just slightly from what is shown here to give a small ridge to positively hold the bearings in the pockets and making the rod clearance slightly longer because in the test it came out with basically zero clearance and the rod is rubbing at the ends. With those changes it should be good to go and reduce the friction in the belt turns to negligible amounts.

Got the final design now and will post the .stl files this evening if anyone is interested. I added a raised section to create pockets for the bearings to lock them in place. The rods I used were 10 mm dia and 80 mm long from PDTech (http://a.co/gu7TEAV) at $6 each cut to length. The bearings are Koyo HK1010, 10 mm ID, 10 mm long, and 14 mm OD (http://a.co/2sf6ITj) at $4.20 each. I'm using three assemblies since the shoulder harnesses get doubled up so parts cost is less than $50 besides the plastic. Friction is way down over pulling the belts 90 degrees around the frame through 3D printed guides. Haven't tested the whole thing out yet but I'm pretty sure it's going to work well. With the ball bearings in all the turning pulleys just about all of the pull from the motor should now end up in the seat belts. At about 12 pounds of pull on each belt, it won't squeeze the breath out, but it should provide the sensation and the spring will provide some give.

Edited to add the .stl files for the mount in a zip archive and a Fusion 360 image of the final version where the bearing retainer bit is showing. Got one mounted now on the shoulder harness side with the double belts (still printing the other two) and it makes a huge difference in the friction! Looking forward to being able to try it out.

Hey @RacingMat - these kind of show the layout. It's pretty tight in there but if you trace the cord, you'll see the setup as implemented. I have to say those rollers do really help out. Now that top is mated to bottom, the cord runs free and I think the seat belt tensioning will work fine. Still not tested and the final knot not even made, but as is, everything is running low friction.

from idea, to sketch, to realisation!
that's great

eager to see forward the test

Can I order harness kit? what is pricing. Cn it interface with Sim Commander?

Thanks

what's is your feedback after these period of time @Zed?
still the same design?
yours

Hey Mat, the system works but the motor and arm I used doesn't have the stroke or the force to be especially effective. I haven’t had the chance to do anything to fix it. The wide ball bearing strap rollers and ball bearings in the pulleys are all important, though. Also thinner rope than in those photos.

In hindsight, I think bike brake pull cables would be a better solution, but for my setup I’d still need a location for the actuator. The base of the chair is very crowded so the harness has been relegated to when I get around to it.

Cheers!

I am thinking about a configuration where I would pull down the belt buckle with a bowden cable running between the legs. That way, I do not have to translate forces around corners (bowden takes care of that) and can mount pretty much all the hardware on the static part of the rig.

Do you have any advice on what kind of actuator you would use to exert enough force for it to be realistic?

@Avee : you really should open your own topic
it'd be easier to help you and it will not pollute this topic

here some topics with bowden cable:
https://www.xsimulator.net/community/threads/g-head-bowden-cable-based-surge-system.15046/

https://www.xsimulator.net/communit...eat-on-6dof-v1-finished-v2-in-progress.12314/

https://www.xsimulator.net/community/threads/diy-g-seat-insert-using-1-ac-servo-wip.14044/