I find that needle roller bearings have more 'play' and they wear the shaft and they can't take any axial load. But apart from that good low profile and load capacity.
Not too sure how they compare in friction/free running properties, don't imagine it'd make a lot of difference.
Some more progress today, got a couple of gears machined... will update photos next time.
Here is the next installment of NST's Scorpion Gearbox upgrade...
Front gearbox plate machined and all internal gears shafts and bearing installed. Taken a good deal of time over this, hopefully won't need to rush the rest too much lol.
Note to self: Bring bin bags on friday...
Just noticed that I haven't posted any updates since before the UK champs....
Seeing as the old Dewalt set up proved so successful, I've decided to stick with it and leave the brush-less set up to one side for a future machine.
It was time to improve a couple of things on the machine which have been bugging me...
First of all some pics of the new custom built Solid state relay. successfully trialed at the Robo-challenge awards ceremony and testing days.
Hoping that the extreme rating of this unit will guarantee that it doesn't get overloaded at all and so should never fail short like all the off the shelf SSR's I've tried previously.
Next up the complete replacement Dewalt front end & gearbox. I decided to rebuild this to save a little weight and because the mounts were getting a little tired.
The original unit was made in a hurry for the first NST only a few weeks before the 2010 champs. It was made with things I had lying around. This time better choice of parts have been used.
Slightly downsized the bearings from 12mm to 10mm.
New grade 5 titanium shaft replaces the old 12mm silver steel one.
lightening pockets added and lightened bevel gearwheel.
Also forgot how long it takes to make one of these....
So you are swapping out the chain drive for the direct drive system? And all this weight you keep saving here and there, where is it going to go?
This version has got back to the chain drive for now as it was at the open day as it proved to be reliable. Extra weight can go in many areas like bigger batteries for higher voltage to the disc, bigger magnets, or heavier teeth
The plan is also to stick with the chain drive set up as I know it works well enough.
It does seem a shame to abandon all the shaft drive components, but to use them with the Dewalt, i'd have to build a whole new gearbox.
That is a very good question. I'm not 100% sure yet how the weight will pan out. But for certain I need to add some decent chain tensioners to the weapon chain also need to support the back of each drive motor to improve reliability as they loosen from their gearboxes over a competition.
Depending on what's left, I've thought of 4 options:
- Bigger weapon battery (higher capacity)
- Go up to 8 cell on the weapon (& alter chain drive ratio => faster spinup & higher top speed)
- Improve some of the weaker armour
- Bigger teeth
Thanks Grant, I almost forgot about adding extra magnets
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