NST

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.

Quite abit more work...

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

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

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.

Glad to see you finally have the featherweight bug :)

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.

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? :lol:

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 :)

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...

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?

Hi Sam

Great looking robot

sent you a pm concerning your upgrades :)

alex

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

Cheers guys! Think i'll keep with the brushed motor again so can hopefully hang onto that title 8)

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 :(

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.

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.

and abit more progress mainly more lightening

Finally...

Need some decent button head bolts to finish it off and modify the shaft to suit sprockets. That'll prob just be a keyway and grub screw. Then can machine off the excess shaft.

That's looking awesome sam, some inspiring work there mate!

Cheers James, Looking forward to hearing more about your new machine!
Its good to be able to work on this sort of thing at a relaxed pace rather than my usual trick of rushing before an event.

I'm relieved that the gearbox is working well now after some minor problems on its first test. Needed to make a couple of mods to the front plate and integrate 2 12mm bearings instead of the single one and a nylon insert. This should now run more efficiently with side loads on the shaft from the chain tension.

A bit more progress....

I've modified a pair of the excellent robo-challenge blue wheels. Now fitted with needle roller bearings and sprockets. Taken a gamble tapping into the plastic, some harsh testing of the drives will be needed to see if the threads are likely to hold!

A couple of wheel & chain tension mounts CNC'd from 3.2mm hardox.

Some good progress on the second gearbox housing.
This one will have a different front bearing housing including a pair of idler gears to correct the forward direction of the motor on one side.

looking good Sam, pretty heavy duty chain tensioners! lol

You say idler gears... you mean one gear on the output of the gearbox running against a second to reverse the direction of the output? Nice work so far though mate. Get a picture of them in the machine :)

Cheers dude, its getting there slowly..

Yep thats exactly it. I've ordered the bearings and gears and drawn up a design. But it involves alot of effort and adds weight and i'm starting to feel that i can't be bother to make it now.... as looking more carefully at the motor again, it might be easier to butcher it to fetch the timing back after all.... even if it means remaking the back of the motor.

shouldn't be too long till their ready to install....hopefully

Decided to go on with the idler gearbox design and keep the motors standard.

Got on the CAD to design this one, then wrote 3 pages of G-code for the machine. Spent way too many hours on this...... but it does look quite cool and shaved most of the grams off possible.

Theres just one more plate/cover which needs machining to go on top with the other bearing supports.

wow! :o

Lol cheers Harry.

Some more progress over the last few days....

Finished the outer bearing support for the idler gearbox. Machined ti shaft, fitted spockets and keywayed both gears on.

As it turned out the 'cover plate' took as long to make as the housing itself but turned out quite well.

Assembly in the chassis at last..... with the chains fitted and gearboxes bolted down.

This shows the aluminium inner wheel mounts too. Also the now pocketed triangular part of the baseplate.

how is it posible for it to look sooo good?

Time, patience and a CNC mill

Looking epic mate

AWESOME :shock:

EPIC
that is sooooooooooooooooooooooooooooooooooooooooooooooooo ooooooo cool

Very nice Sam :D

But how is it going to stop The Mighty Seraph :uhoh: :uhoh:

Thanks for the comments guys :)

In all honesty Craig I think your right, NST just can't stay in the arena lol. With hindsight the NST design is too unstable. Fun to use but not predictable enough for competition. I have enjoyed the challenges of the build and will use the current chassis for at least another competition, hopefully the time consuming gearbox parts will survive and can go into another better designed machine in the future.

I'm on the hunt for a dual motor speedo, Dave recommends the Scorpion XXL (that looks ideal tbh). Does anyone know of any alternative controllers of that spec on the market in the same compact package?
Looks like robotmarketplace have stopped doing the scorp xxl :(

i got an xl or an xxl and then rick maas upgraded it for me adding extra bits and boobs casing fans in and out etc this maybe within your knowledge and remit though but the best controller ive ever used

Quote:

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Originally Posted by psycho_fling

rick maas upgraded it for me adding extra bits and boobs

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I never knew those were a possible addition when you got an upgrade?! :shock:

Or was that just a Freudian slip from you Marler? :wink:

[quote=k_c_r]

Quote:

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Originally Posted by psycho_fling:2evc70ya

rick maas upgraded it for me adding extra bits and boobs

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I never knew those were a possible addition when you got an upgrade?! :shock:

Or was that just a Freudian slip from you Marler? :wink:[/quote:2evc70ya]
:rofl:

sorry to disappoint you guys but it was a slip of the mouth i had things on my mind :proud:

*bobs lol

Quote:

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Originally Posted by psycho_fling

i had things on my mind :proud:

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Obviously :lol:
And great, now I'm going to get different images in my mind when someone talks about increasing the size of their FETs!

FET envy can be a terrible thing Jamie.

Looking really good Sam