Thingiverse
Modified files for improved OpenRC Truggy printed parts performance by dazmatic
by Thingiverse
Last crawled date: 4 years, 3 months ago
When I started printing the Open RC truggy, I found that it was EXTREMELY difficult to source parts in the UK. For example, the driveshafts from conrad are expensive, expensive to ship and usually out of stock. However, HSP 188015 driveshafts are massively cheap and are in abundance everywhere!
So, this is my OpenRC Truggy remix page where over the continuing build I shall upload all the files that I modify and my reasons for it to make the life easier of those wanting to have a go at printing this cool machine.
188015 axle shaft.
Originally, this was designed for use with the conrad drive shafts which are expensive and difficult to source. I wanted to use the 188015 driveshafts which are the opposite. However, they are slightly too long for the original differential output shafts/axles.
On top of this I found that my original redesign of the output shafts, whilst working, wasn't nearly strong enough. After several iterations of designs, I decided upon this final design making use of 4x 1mm dowel pins approx 10mm in length around the main screw. This adds a metal, positive drive to the shaft output. It's a little fiddly and I would recommend printing 100% infill and using a 1mm drill to clean holes and 2.5mm drill to clean centre hole to ease assembly. Also, pre-tap the centre hole with a screw to ease assembly.
You'll find that the holes in the outer axle shaft are slightly further apart than the sun gear, that's on purpose to ensure that the pins splay outwards when tightening as if they didn't they'll splay inwards and damage the screw.
Rear C-Hub.
I take issue where bearings are concerned. If you've got a 5mm shaft in a 5mm bearing, don't make the hole the shaft runs through 5mm also because the inner race of the bearing isn't 5mm, it's more like 7mm. That means when the bearing is pressed in, the inner race rubs up against the back edge of the hole it sits in causing the inner race to bind. With this mod, I've expanded the hole from 10.1mm to 10.2mm to ease fitment of bearings and reduce compression of the outer race (less binding/wear/longer life) AND made the internal hole 7mm so that the inner race runs clear and free and what a difference it made!
Steering Pin.
So trying to find the 5mm ball headed pins was also a pain in the rear, needlessly difficult and entirely uncommon. I've henceforth modified the steering pin cups to now accept the HSP 02038 ball head screws. It's a tight fit and to be fair, doesn't look very durable but I'll soon find out when I eventually get the car moving. This one is open to debate and if it's no good I'll increase the thickness around the open ends to strengthen it.
Steering Block.
Same reasoning as the rear C hub. Expanded the bearing holes for an easier bearing fitment and expanded the centre hole so that the bearing inner race isn't binding up on the hub.
Steering part 1/2.
Expanded the holes for an easier bearing fitment. Wasn't enough space to expand the centre hole to prevent the bearing inner race from binding on the part so instead I extruded a small shoulder, about 0.4mm, to raise the outer race away from the face of the hole, thereby moving the inner race away from the undersized hole and preventing any binding there
Servo Holder
I opted to use the MG996 servo as they're common as muck and just as cheap. However the servo holder was a little too small to hold it do I've modified the design to suit. Be sure to use the rubber grommets also
Centre differential output shafts
So after strengthening the front/rear diffs, it was then found that the centre diff was now susceptible to the same issue of snapping either the the input side square or output side joint. In response to this I applied the pin design to the shaft increasing the strength of the power train even more so.
So, this is my OpenRC Truggy remix page where over the continuing build I shall upload all the files that I modify and my reasons for it to make the life easier of those wanting to have a go at printing this cool machine.
188015 axle shaft.
Originally, this was designed for use with the conrad drive shafts which are expensive and difficult to source. I wanted to use the 188015 driveshafts which are the opposite. However, they are slightly too long for the original differential output shafts/axles.
On top of this I found that my original redesign of the output shafts, whilst working, wasn't nearly strong enough. After several iterations of designs, I decided upon this final design making use of 4x 1mm dowel pins approx 10mm in length around the main screw. This adds a metal, positive drive to the shaft output. It's a little fiddly and I would recommend printing 100% infill and using a 1mm drill to clean holes and 2.5mm drill to clean centre hole to ease assembly. Also, pre-tap the centre hole with a screw to ease assembly.
You'll find that the holes in the outer axle shaft are slightly further apart than the sun gear, that's on purpose to ensure that the pins splay outwards when tightening as if they didn't they'll splay inwards and damage the screw.
Rear C-Hub.
I take issue where bearings are concerned. If you've got a 5mm shaft in a 5mm bearing, don't make the hole the shaft runs through 5mm also because the inner race of the bearing isn't 5mm, it's more like 7mm. That means when the bearing is pressed in, the inner race rubs up against the back edge of the hole it sits in causing the inner race to bind. With this mod, I've expanded the hole from 10.1mm to 10.2mm to ease fitment of bearings and reduce compression of the outer race (less binding/wear/longer life) AND made the internal hole 7mm so that the inner race runs clear and free and what a difference it made!
Steering Pin.
So trying to find the 5mm ball headed pins was also a pain in the rear, needlessly difficult and entirely uncommon. I've henceforth modified the steering pin cups to now accept the HSP 02038 ball head screws. It's a tight fit and to be fair, doesn't look very durable but I'll soon find out when I eventually get the car moving. This one is open to debate and if it's no good I'll increase the thickness around the open ends to strengthen it.
Steering Block.
Same reasoning as the rear C hub. Expanded the bearing holes for an easier bearing fitment and expanded the centre hole so that the bearing inner race isn't binding up on the hub.
Steering part 1/2.
Expanded the holes for an easier bearing fitment. Wasn't enough space to expand the centre hole to prevent the bearing inner race from binding on the part so instead I extruded a small shoulder, about 0.4mm, to raise the outer race away from the face of the hole, thereby moving the inner race away from the undersized hole and preventing any binding there
Servo Holder
I opted to use the MG996 servo as they're common as muck and just as cheap. However the servo holder was a little too small to hold it do I've modified the design to suit. Be sure to use the rubber grommets also
Centre differential output shafts
So after strengthening the front/rear diffs, it was then found that the centre diff was now susceptible to the same issue of snapping either the the input side square or output side joint. In response to this I applied the pin design to the shaft increasing the strength of the power train even more so.