Help with choosing parts for a first robot, please.

[harry hills]

Black and decker are generally pretty bad now so i'm not surprised.Putting holes in plastic most drills just fall though, its weird you can't do it. Maybe charge the drill and try again but...

I would advise getting a cheap drill press though mate. Even a basic one will mean you can do straighter holes than by hand (which you need for doing the wheels and stuff) and just general work its a great tool to have. I was without one for years and I don't know how i survived.

[Ellis]

That^

Even a cheapo thing, talking £50 region, will serve you well. They aren't quality tools but they are a world away from handheld. I have owned and abused 2 such cheap things and with a bit of care they aren't bad.

Also, I assume the bore of the wheel is already fairly large. In soft plastics, drilling a hole to a size only a little bigger than its starting size often causes the material to tear and compress, which a lot of the time results in violently grabbing the bit. Either the part/drill shift violently, the bit snaps, or the drill stalls. Sounds like you're experiencing the latter. It's good practice with plastics to, where possible, drill a small pilot hole or none at all. I try to stick to pilots no bigger than 1/3rd the next drill's size.

What size bore are they to begin with? I did the melted-nut-bore thing a long time ago and if I recall melted them straight into the 12mm bore the 100mm wheels had as standard. Are yours not 12mm?

[typhoon_driver]

You can usually find small pillar drills going on gumtree for around £20 up this way. Your other option is a holder for a hand drill that turns it into a pillar drill.

[dotDominic]

Thanks very much for your responses!
Sounds like a good idea to hunt down a cheap pillar drill.

@Ellis
Yeah, the bore is originally 12mm, and the inserts are 15 mm across. I'd read in other threads regarding wheels that the nut insert could be hammered into the bore if it was increased to 14 mm. I've watched your videos where you melt the insert into position, but without the more precise movement of a pillar drill I was a bit cautious about trying it out.

[harry hills]

I wouldn't hammer them in if I were you. It seems like a recipe for wonkeyness. Use a press or even heat the nut and use the drill press like a press (like Ellis's video) and its much better

[maddox10]

Don't go for the holders, unless you need to drill a lot of holes in stone using a hamerdrill. (never found a pillar drill with hammer function)
In any respect, those are just a third rate backup.

I only can advice, go for a real pillar drill, and not the smallest ones either. I had one of those, and Kos made me a longer pillar, making it a lot more useable.
But on the other hand, those are cheaper than a good brand batterydrill ,and they can drill a straight hole.

I have this one, and I'm going to get a bigger one as soon funds allow.


Maybe this one.

[Ellis]

Only major issue I've found, having owned two cheapo smallest-scale pillar drills, is that you need to stick some wood under the table so it doesn't flex when doing anything more than popping small holes in soft materials. Aside from that they have surprisingly little chuck wobble, etc. Of course I'd love to have a nicer, bigger piece of kit (with some slower speeds) but, funding.

I still strongly recommend you try and get one, it's a massive evolution from hand-held. Used via Ebay/Gumtree is certainly an option for cutting costs further.

As for the wheel bores, it seems that you'll likely need a pillar drill to do either thing: drill out the bore with any accuracy, or use it as a form of press to do the heat-insert method with the stock bore. Problem with hammering into the (probably nylon or polypropylene) wheels is that they will likely crack and wheel-wobble, even if it doesn't, will be bad.

With the heat method the plastic actually captures the nut in all directions, from the sides as well as rotationally. The wheels in our old how-to videos are still completely solid after dozens of harsh fights several years on.

[dotDominic]

Thanks for the responses!

I really don't have the cash for one of those bigger pillar drills, but I'll definitely check out getting a cheaper one.
And if I'm going to buy a pillar drill I'll use Ellis' melting method for the wheels rather than hammering it.

Thanks so much for your help!

[dotDominic]

Just finished cutting the HDPE. Could've been tidier, but it all fits together so it should be ok. Also the pillar drill arrived in the mail yesterday so I'll be able to assemble it all soon.

[shakesc]

Good work
The pillar drill will certainly help accuracy

[Ellis]

Looking good!

[dotDominic]

Just realised that it's been nearly a year since my last post on this thread, so I thought I'd make an update. Progress has generally been very stop/start as I live in halls of residence at University, so unfortunately I can't really work on the robot during semester time.

13479477_10205039041856060_323680255_n.jpg ACTUAL VENATOR INSIDES OH MY GOSH.jpg ACTUAL VENATOR OH MY GOSH.jpg

Although Venator isn't quite up and running yet it actually looks like a combat robot now! That's pretty much everything except the battery, steel wedges, power LED and mountings. I also really annoyingly blew something up in one of my ESCs about a month ago so I'll need to do something about that too.

But considering I knew next to nothing about electronics or D.I.Y. before starting this project I'm really happy with how this has turned out so far. (Just pretend those misaligned holes on the lid aren't there.) Hopefully it will actually work when I finally get to turn the thing on!

[Andy]

Looks really nice, good job!

[Coolspeedbot]

Just realised that it's been nearly a year since my last post on this thread, so I thought I'd make an update. Progress has generally been very stop/start as I live in halls of residence at University, so unfortunately I can't really work on the robot during semester time.

[ATTACH=CONFIG]5919[/ATTACH] [ATTACH=CONFIG]5920[/ATTACH] [ATTACH=CONFIG]5921[/ATTACH]

Although Venator isn't quite up and running yet it actually looks like a combat robot now! That's pretty much everything except the battery, steel wedges, power LED and mountings. I also really annoyingly blew something up in one of my ESCs about a month ago so I'll need to do something about that too.

But considering I knew next to nothing about electronics or D.I.Y. before starting this project I'm really happy with how this has turned out so far. (Just pretend those misaligned holes on the lid aren't there.) Hopefully it will actually work when I finally get to turn the thing on!

How did you fix the side panels to the center frame? (those blocks between the front and back wheels)

[dotDominic]

Thanks, Andy.

@CoolSpeedBot There's a 100 mm bolt which goes through the length of the block, with a barrel nut in the middle. Then there's a hole in the side of the inner bulkhead which allows it to be held in with a washer and nut. Here's a photo of one that was a bit iffy, hope it makes sense.

IMG_3663.jpg


Right now it's the only thing that's holding the wedge and outer armour to inside - now I can see where the wedge actually sits I can bolt it to the inner bulkheads.