Max, hadn't thought of doing that but yeah I suppose it's something I could try.
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Max, hadn't thought of doing that but yeah I suppose it's something I could try.
I would be particularly careful with cutting plastic - a grinder spins much faster than a circular saw and with a high tooth count blade, its likely to melt the plastic and grab. I found that the best blade for cutting PE plastics is a ripping blade with a low tooth count. The ease of cutting VS any type of cross-cut blade is amazing and they are also cheaper.
What Nick said
I use a circular saw for cutting HDPE with a wood ripping blade. Get good clean cuts
There was actually a blade with a lower tooth count but I brought this one because I thought it would be better, I'll test this one for now and if it doesn't work then I'll look at something else.
Putting the disc on the back burner for now and focusing on the bar weapon seeing as that will actually fit on my drill press. Brought a piece of 6082 (250 x 60 x 15mm) and I'll attach one of the huge steel teeth for the disc either end, should be a better weapon as more of the weight will be on the outside and I should be able to knock it up fairly quickly.
Update!!
Started on the chassis today and overall it's gone pretty well, the saw attachment for the grinder works really well and cuts cleanly without any problems, some slightly rough bits but i'll tidy those up later on. Going to cut the baseplate out later on today but for now here's a couple of pics with the disc plonked in the middle for Pretendobot effect. http://i921.photobucket.com/albums/a...ps2d8b8780.jpghttp://i921.photobucket.com/albums/a...ps509c3d84.jpghttp://i921.photobucket.com/albums/a...ps3ac71d8a.jpg
I would move those bulkheads closer together of possible, you want the shaft for the disk to be as short as possible to avoid bending (and save weight).
But looks like a really cool shape robot, very original!
Looks great Sam :)
Cheers Max, it's actually based around IG88/Vader so not all that original, the shaft is going to be 25mm so it shouldn't bend (hopefully) but i'll move them as close as i can.
Never say something 'shouldn't bend', the spinning a will most likely make a point to prove you wrong :).
I would wait with cutting the baseplate for the moment and get the weapon ready.
For that will determine the dimensions in the end. Unless everything has been calculated up front.
That's actually exactly what i thought not long after posting, i have measured everything out but it's probably better to wait and just make sure everything fits.
It's generaly the smart thing to do, unless offcourse you have baseplate material to burn.
A middle way would be to use wood to give the bulkheads the stability they need to fully test the weapon without using more valueable materials.
The base is non structural so once i've cut out the rest of the chassis and bolted it all together with the weapon in place it'll be ready for a spin test if i clamp it down.
More Progress!
Drilled the bulkheads today so i could fit the bearings in, actually went really well and i'm pretty happy with the end result. Whilst it's not perfect it's as little as makes no difference. Picture spam forthcoming...
http://i921.photobucket.com/albums/a...ps8268e606.jpghttp://i921.photobucket.com/albums/a...psbe5fe375.jpghttp://i921.photobucket.com/albums/a...ps0ee34fcc.jpghttp://i921.photobucket.com/albums/a...ps03f14328.jpghttp://i921.photobucket.com/albums/a...psa0cb9c9a.jpg
Nice!
Looks great, very cool shape!
Just a quick one, I've got the aluminium for the bar and need to drill a 25mm hole in the centre, I have a 25mm drill bit and a 25mm hole saw which one would be better to use? I know Nick mentioned using hole saws but what does everyone else think?
Drill bit! Pilot that to hell as well, I tried drilling through 10mm ali with a hole saw at only 12mm. Yeah..... nope
Just dust of the old laser and be done with it :D
But yeah, drill bit. First a 2mm hole, than a 6mm hole, than a 12mm hole and than the 25mm hole. Each hole will help keeping the bigger drill centered.
I'll try the drill bit then, doubt it'll be fun either way but the bar should be on by tomorrow
Cut the teeth for the bar today and it went really well, the thin discs cut out both teeth in a couple of minutes and really accurately. These things are huge though and just for the record around 450g each. http://i921.photobucket.com/albums/a...ps726d3396.jpghttp://i921.photobucket.com/albums/a...psc05435b9.jpg
Cut the baseplate as well earlier and assembled everything for full on pretendobotness, looks pretty good so far if I do say so myself. http://i921.photobucket.com/albums/a...psdd0121b5.jpg http://i921.photobucket.com/albums/a...ps99f188e9.jpg http://s921.photobucket.com/user/mrs...pse696603d.jpg http://i921.photobucket.com/albums/a...ps10faec31.jpg
This is progressing crazy fast - nice work!
Cheers Nick, there are some bits i'm not all that happy with but seeing as it's only for whiteboards and demo's it doesn't need to be perfect first time round. Will hopefully have the teeth on the bar and the bar on the robot by the end of today.
Was going to start on the bar today but Father duties come first, so just as a little taster here's all the parts for the bar "assembled" in a stacky fashion. For those interested the finished weight is around 1.5kg. http://i921.photobucket.com/albums/a...pse690868c.jpghttp://i921.photobucket.com/albums/a...psfaa0ac4c.jpghttp://i921.photobucket.com/albums/a...psc3dba9d7.jpghttp://i921.photobucket.com/albums/a...ps8b7f4273.jpg
Having the teeth on opposite sides of the bar will make it dynamically unbalanced, which will shake the bot about and cause bearing wear. Its better to put the teeth on the same side.
Ah okay cheers Nick
Also, assuming it's to spin clockwise (based on the pic), having the chamfered corner where it is will prevent you from getting hits on low targets. Flipping the teeth over will give you a big bludgeoning hitting edge, the tip of which is the maximum diameter of the weapon so it'll always hit on the flat.
I'll give them a flip then, good thing i posted the pic before i got to drilling, would have hated to take it all apart again.
Use the term 'teeth' loosely, more like 'thick blunt hitting spinning objects that will bludgeon machines'
Yeah they're not exactly teeth are they? I've affectionately named them 'arse kickers'
Better guys? Should get it all done tomorrow
http://i921.photobucket.com/albums/a...ps96414fd7.jpg
looks good to me!
And so it Begins......http://i921.photobucket.com/albums/a...psadac40ea.jpg
Annnnnnnd it's done! well the large hole for the bar is at least, really happy with how it went, the bar is a 'little' off balance but nothing too bad i hope but i'll know for sure once it's all together. For now though here's some lovely pictures http://i921.photobucket.com/albums/a...ps69809025.jpghttp://i921.photobucket.com/albums/a...psd2cc67d2.jpg
Real horrorshow man :) Really well done so far. Much respect.
I do love to see it spin up, it looks terrible to face :D
Yeah, you can stop building that now :)
Aha i think i'll carry on, might even enter it in the main Champs next year :angry: