NST

[sam_smith]

I'll roughly recreate the build of NST with some pics of main components from the last few weeks...

First the Dewalt 24 volt motor upgrade & gearbox unit.
This is the black for the dewalt front end.

[sam_smith]

Re: NST

Quite abit more work...

Just needs the ali centre for the bevel gear machining and a shaft making.

[james...venom]

Re: NST

Awesome bit of machining sam. Robot worked incredi ly well for. Its first outing

[sam_smith]

Re: NST

Cheers James, That part was worth all the effort i recon. This week i've been ive been machining the upgraded back part of the motor, something I didn't get time to do before the champs. I'll put some pics of that up soon.

In the meantime, here is some more of the original build diary...

An early stage of the titanium bar, lower ali bearing support, and titanium shaft.

I machined the Titanium shaft first to 30mm diameter for the main part (as shown). Thanks to Grant for advising thats overkill. Saved 250 grams going from 30mm to 25mm bearings, a few more grams saved on the shaft and potentially saved the bar from snapping as the hole (weakness) through the weakest part of the weapon bar was reduced in size.

[typhoon_driver]

Re: NST

Glad to see you finally have the featherweight bug

[sam_smith]

Re: NST

Oh aye
Recon tiberius is going to gather some dust for a while now!
Such a handy weight class to work on....
Being able to work on it inside the house is always a bonus during winter.

Heres a couple of pics of where NST was in the build 8 days before the UK champs.

The white cardboard box was the size of one of grants 6 cell lipo packs.

[RogueTwoRobots]

Re: NST

Is it sad that my eye isn't drawn to the nice motor mount or the lovely looking spinning bar, but to the copy of Professional Engineering magazine sitting on your table?

I have to say, the effort that's gone into the motor mount definitely paid off when it came to running in the arena; it's reliability was brilliant. Keep the pics coming

[sam_smith]

Re: NST

Lol, I wondered which prof-engineers would notice that.
Cheers dude, it took some stick for sure. I didn't mount it the best in the hurried build and noticed recently that the big bevel gear chewed some of the edges of the stainless steel bulkhead which it sits near. That unit must have moved a fair bit in the impacts.

Nows a good time for a recommendation to anyone who plans to use a dewalt 24v motor....
In my opinion the important parts of the standard dewalt drill motor are well made (armature & mag casing). The front and back casing are perfectly fine for a drill but no good for combat as the screws are made into plastic. The standard motor back plastic part is known to melt when abused in combat as the brushes get hot. To overcome this Robot market place sell a high temp brush housing, which is watercut from high temp plastic. While this cleverly overcomes temp issues and cunningly provides you with neutral or advanced timing option in each direction, it has two big flaws....
1) There is no good means of alignment or strength to support the back bearing (which ended up smashing the magnets with the armature in the original motor and my spare which I swapped out half way thru the comp).
2) the brushes are supported less securely than if you were to use gaffa tape!

I didn't have time to solve either of these before the comp but expected probs. So i'd recommend the motor but save your 60 dollars (and motor's magnets!) and think of a cunning way to replace the back of the motor. This is how I have gone about it with abit more time...

[sam_smith]

Re: NST

I forgot to mention that in the rush of the last 7 days of building I didn't take any photos, so will jump onto current work as above.

Many thanks to Grant and James for their help in the last week. Without which NST would certainly not of been ready for combat for the champs.

Heres the lastest on the dewalt upgrade.... now with the mounting holes completed. I'm still trying to find a plastic suitable for attaching the brushes. Anyone got any advice???

I've been considering nylon, or teflon, but could do with a thermoset really, ideally one with some toughness?

[psycho_fling]

Re: NST

Hi Sam

Great looking robot

sent you a pm concerning your upgrades

alex

[Mouldy]

Re: NST

Nice work Sam... Best brushed fw spinner i've ever seen for sure.

[sam_smith]

Re: NST

Cheers guys! Think i'll keep with the brushed motor again so can hopefully hang onto that title

Now the weapon motor is nearly finished i've got bored of that and moved onto something else....

New drives....

Figured with all the effort i'm going to put in to make some decent gearbox cases, might as well start with some reasonable quality motors and gears. There are quite a few Dewalt drills available on Ebay pri cheap.

Picked up two new 12v Dewalt drills (without battery or case or anything) for £25 each.

Work has started on some new housings

Keep forgetting to post pics in reverse order

[sam_smith]

Re: NST

Might as well get right upto date....

some more machining to fit the motor and planetary gear assy's
Will ditch the first stage of gearing which is used with the 1st gear on the drill to save space, weight and give a more suitable output speed. Luckily the second stage has the same size and pitch teeth (with just a wider face width) so the motor sun gear is compatible into stage 2 which is handy.

Something annoying I found out after buying these drills is that they have advanced timing so unless i can get into the brushes to amend (which isn't gonna happen cos the motors swaged together) looks like will have to add an idler gear to one of the gearboxes, or each side will always have different power and speeds.

ali housing down to 110 grams now from 250 ish as a solid block, will turn the middle portion down next to save some more weight.

[sam_smith]

Re: NST

Heres some of the progress from the weekend. Turning out to be very time consuming unit...
but taking shape well at least. More lightening and mounting holes drilled out.

[sam_smith]

Re: NST

and abit more progress mainly more lightening