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MBX - Team Knightrous - QLD
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Knightrous
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Joined: 15 Jun 2004
Posts: 8511
Location: NSW


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Changed my mind on the gearbox design. Last one ended up too long, so I went for a bit of an odd design.


Still gotta add some clearances here and there, fixture point and probably design a milled out plastic housing to cover the gears. Looking forward to trying my luck on milling a large portion of it on my new milling machine (when it gets here Sad )
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Post Thu Jun 11, 2009 11:06 pm 
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Nick
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Joined: 16 Jun 2004
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Location: Sydney, NSW


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Why not go with two larger, wider gears? Much easier to make and more compact.

Post Thu Jun 11, 2009 11:16 pm 
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Valen
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Joined: 07 Jul 2004
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I wonder if rather than trying to accelerate and decelerate a motor, it might be easier to apply a brake to the motor. (mechanical or electrical)
Just something to think about
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Post Thu Jun 11, 2009 11:27 pm 
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Knightrous
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Joined: 15 Jun 2004
Posts: 8511
Location: NSW


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quote:
Originally posted by Nick:
Why not go with two larger, wider gears? Much easier to make and more compact.


MOD1 or MOD1.25 gears from SDPSI didn't come in the ratios I was looking for, and I need this gearbox to be an inline solution, no offset output. The box is 2 stages of 1:1.4. I was originally going to double the gears up on the second stage, but it ended up making the gearbox too long, so I came up with the above solution. Gearbox is 80mm long, 70mm tall and 50mm thick (shaft not included). I could reduce the thickness if I machine all the bosses off the gears and keyway them to the shafts, might be something I do in the future with the mill and some new tools.

Hopefully it should hold up, if not, I'll design something else Smile

quote:
Originally posted by Valen:
I wonder if rather than trying to accelerate and decelerate a motor, it might be easier to apply a brake to the motor. (mechanical or electrical)
Just something to think about

I've thought about that before, but never really gone much further into it because it's just 10x easier to pulse it. Anguz and I have a melty brain chat on msn and we discussed using a h-bridge for the braking and pulsing side of things. Big problem is I'm not aware of any small 25A h-bridges that handle 40v and are small enough to use (I don't want to have to put a Victor in there!).

I've had other crazy ideas with using 1 big brushless that drives two wheels and the opposite wheel is speed controlled via an electronic differential, similar to FireStorm's drive but it just complicates things damn fast Razz
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Post Fri Jun 12, 2009 8:15 am 
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assassin



Joined: 27 Jun 2004
Posts: 1105
Location: SunshineCoast


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Which Mill did you decide on? I might look @ one with my tax return this year.
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Post Fri Jun 12, 2009 10:05 am 
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Nick
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Joined: 16 Jun 2004
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Location: Sydney, NSW


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I guess its more interesting and challenging to build your own gearbox, but it looks like one of the Banebots P80 single stage planetarys would do the job. After buying all those gears, shafts and bearings, the cost might not be that much different.

Post Fri Jun 12, 2009 11:02 am 
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Knightrous
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Joined: 15 Jun 2004
Posts: 8511
Location: NSW


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@Nick:Never thought of the P80 boxes, ratios will probably be wrong for me though.. I need a 1:2 gear ratio, I'm gearing the scooter motor up, not down. Good suggestion though, I might consider those if I ever make up some small boxes for scooter motors in the future. Always like the prospect of a scooter motor with a compact 4:1 gearbox on it instead of the annoying belts Smile

This gearbox will cost me about $100 all up once I get all the parts, and building my own gearboxes is rather rewarding from a personal perspective. My Ionboxes for Schmackhed (as rough as they were) worked well, till I started breaking the drill internals. It was a fun experience making them too, had to think outside the box to machine square billet with a 3-jaw chuck Smile

@Trent: Ended up getting the M150, still waiting for hafco to deliver it though, paid for it two weeks ago Evil or Very Mad Think I'll spend my next tax check on a bunch of tools for it, or maybe an Ebay Tig welder.
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Post Fri Jun 12, 2009 11:31 am 
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assassin



Joined: 27 Jun 2004
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Location: SunshineCoast


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I'm liking this bad boy:

http://titanmachinery.com.au/index.php?option=com_content&task=view&id=14&Itemid=32
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Post Fri Jun 12, 2009 2:15 pm 
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Knightrous
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Joined: 15 Jun 2004
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Location: NSW


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That's a kick ass mill, just a shame about the price tag Sad
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Post Fri Jun 12, 2009 7:23 pm 
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Glen
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thats the mill i was looking at too, if you could get one with an MT3 taper. that or the 5 grand one at hafco with the DRO. just incase you needed something that big one day Laughing
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Post Fri Jun 12, 2009 8:00 pm 
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assassin



Joined: 27 Jun 2004
Posts: 1105
Location: SunshineCoast


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Its the accessories that make it good value, and apparently the company is good to deal with.

Here's one with a CNC mod:
http://www.youtube.com/watch?v=8PQOQEJyO2w&eurl=http%3A%2F%2Fwww.cnczone.com%2Fforums%2Fshowthread.php%3Ft%3D68153&feature=player_embedded
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Post Fri Jun 12, 2009 8:13 pm 
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Nick
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Joined: 16 Jun 2004
Posts: 11802
Location: Sydney, NSW


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Yeah, its a good option, looks very similar to the Hare & Forbes HM-45 with better paint. Square column mills are definitely the way to go if you have the cash.

Post Fri Jun 12, 2009 8:33 pm 
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Valen
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Joined: 07 Jul 2004
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Location: Sydney


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We have the HM-45.
ballscrews for CnC have arrived, got the .001mm linear scales and I'm going to try 500W motors from oatley for the servo drives.

got the controller card powered up, going to try hooking a linear scale up to it tomorrow when i can get the right IDC header for the control card.
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Post Fri Jun 12, 2009 11:44 pm 
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Knightrous
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Joined: 15 Jun 2004
Posts: 8511
Location: NSW


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I <3 SDPSI!
Ordered the gears on the 11th, they arrived today(16th). Moral of the story, don't order from SmallParts Razz

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Post Tue Jun 16, 2009 3:40 pm 
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assassin



Joined: 27 Jun 2004
Posts: 1105
Location: SunshineCoast


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What was the postage like, price wise?
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Post Tue Jun 16, 2009 6:36 pm 
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