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Philip
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Joined: 18 Jun 2004
Posts: 3842
Location: Queensland near Brisbane


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Tips

What grease should I put in my gearbox? I know that origonally it was a light coloured thin grease.

My wheels were very stiff to turn after Mondays get together so I openned my gearboxes. The grease inside was full of dirt.

I intend to block the remaining holes in my gearboxes with screws, clean the insides out and reapply grease to all components.

Post Fri Jun 18, 2004 5:34 am 
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Ajax
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Joined: 17 Jun 2004
Posts: 298
Location: Sydney


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The correct grease to use will vary depending on the type of gear box that is used, the type of gears (Plastic, Metal, etc.)
Most gearboxs that we are goning to use for the Bots (Drill Motor assy) will use a light general purpose grease. Not the 'Automotive General Purpose Grease' that is to heavy.
It will most likely be white in colour. Don't use the ones that feel gritty between your fingers, they are normaly for high temp's.

A good way of getting the correct grease is to go to your closest bearing supplier, they will be able to help you out. (Remember to take the gear box.)

You also need to remember not to pack to much grease in the gear box, as this will cause you problems. (Gear box could lock up at medium to high speed due to Hydraulics.)

I have a chart somewhere that lists different types of greases and where to use them. I will try to find it, I got it years ago so it may take me a while to find.

I also have to go to Bunnings this week end I will look and see what they have and let you know.

But in the mean time could you let me know the type of gear box you have, then I will be able to help you out a little better.

Cheers Smile
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Post Fri Jun 18, 2004 3:53 pm 
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Glen
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Joined: 16 Jun 2004
Posts: 9481
Location: Where you least expect


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hey phil simple answer to that one.

lithium grease. i get it in a spray can at supercheap and yes it is white as ajax described.

just soak your gearboxes in kerosone and get all the dirt and remaining grease out (leave them to dry) and then re-assemble the gearboxes (for god sake take your time, turn the gearbox after you put one part in and see if it still works freely) and apply the grease to each gear, pin carrier etc then the whole thing when its back together.

i found this frees up the gearbox a great deal, much more efficient and quiet.

btw i wouldnt recommend soaking the motors in kero any more.... i think my brushes blowing off had something to do with it.. (kerosene is a solvent isnt it?)

Post Fri Jun 18, 2004 6:00 pm 
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Totaly_Recycled
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Joined: 15 Jun 2004
Posts: 1346


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Hi Ajax good to see you lurking around the forums Laughing
Andrew Team vertex QLD

Post Fri Jun 18, 2004 8:14 pm 
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Totaly_Recycled
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Joined: 15 Jun 2004
Posts: 1346


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Mm i also hadnt thought of those extra holes in the gear boxes i wil stuff a bit of silastac in al the bots that only have 4 grub screws in them to stop any dirt getting in

Post Fri Jun 18, 2004 8:18 pm 
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Ajax
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Joined: 17 Jun 2004
Posts: 298
Location: Sydney


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Hi Totaly_Recycled good to here from you.

becareful not to put to much silastac in as that will cause even more problems for you
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Post Sat Jun 19, 2004 12:12 am 
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Philip
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Joined: 18 Jun 2004
Posts: 3842
Location: Queensland near Brisbane


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Thank you all. I will do just that.

Post Sat Jun 19, 2004 7:08 am 
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Philip
Experienced Roboteer


Joined: 18 Jun 2004
Posts: 3842
Location: Queensland near Brisbane


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I would like some advice on bar linkages please.

My next design will need some linkages to change the direction of the force from the ram to the flipper bar. It is still a simple flipper not a Biohazard style. The linkages will allow me to reposition the ram.

What is the best way to join bars and keep friction to a minimum? Weight is, as always, an important consideration.

Post Sat Jun 19, 2004 9:33 am 
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Knightrous
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Joined: 15 Jun 2004
Posts: 8511
Location: NSW


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Hey Ajax, good to hear your still around. Are you making it to the NSW Annihilator by any chance?

Also, another tip with drill gearboxes is not to pack them too full of grease, adds a lot of friction to the motors for some reason Cool
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Post Sat Jun 19, 2004 7:10 pm 
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kkeerroo
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Joined: 17 Jun 2004
Posts: 1459
Location: Brisbane


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Ahhh, Aaron, your too much grease tip was already mentioned by Ajax who talked about the Hydraulic effect in the gearbox, but don't ask me, I didn't pay much attention in the tribology lectures at Uni.

Philip, you already have enough moving parts for a great flipper. One thing is though you don't always need the rams to be pushing in the direction you want the other robot to go. Basically your flipper (which is a SWEET flipper) is just a link rotating around a point. You just want it to rotate with another robot on the end. You use the pneumatic rams to push the link around the axis. Now it all comes down to moments. Moments are a rotational force. In you SWEET flipper you have 2 to worry about (or we do), the one caused by the ram and the one by our robot. The moment by the ram = the force exerted by the ram x the distance form where the ram connects to the link to the axis (the point were the link connects to the robot). The one created by our robot sitting on the link = the weight of our robot x the distance from it to the axis. If the rams moment is bigger the our moment then up we go. Create a bigger moment from the ram and we go up quicker.
Oh and since the distances I mentioned in the moments are directly in a straight line between the points and the forces are perpendicular (bad spelling, right angles) to these distances it doesn't matter where around the axis they are. Basically you could have your rams sitting facing directly forward and attached to the flipper directly under the axis, if the distance between the attachment point and the axis are the same as the distance you have now then you'd get the same damn flip you get now. Just look at Thermador 2, it has the same set up I just mentioned.

I wonder if what I said is too confussing.
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Post Sat Jun 19, 2004 8:54 pm 
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Knightrous
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Joined: 15 Jun 2004
Posts: 8511
Location: NSW


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Sorry Ajax if I cut into your previous statement about the grease. I didn't read your post properly obviously. Cheers kkeerroo for the correction Cool

Has anyone looked at replacing the nylon gears inside the boxes with metal ones? I think Glen or Nick were pulling two drills apart to make a single drill with two stages of steel reduction, how did that go guys?
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Post Sat Jun 19, 2004 9:00 pm 
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Spockie-Tech
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Joined: 31 May 2004
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Location: Melbourne, Australia


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I wouldnt bother that much myself.. those gearboxes are "value engineered". that means there is no "weakest link" that is significantly weaker than the rest of the gearbox, and if you just fix that, then they will be heaps stronger.

The Chinese are masters of "value engineering" - ie making things only *just* as strong as they need to be and no more. If they thought they could reduce the diameter of a part by 1/2mm, they'd do it to save the milligrams of metal required. added up over the millions of units they build it represents a big saving.

The next thing that usually fails in the gearboxes is the pins on the output planetary carrier thingy.. they either shear off or come loose and fall out of the holes. no easy way to fix that. what we need to do if you want more reliability from your drives, is find a stronger gearbox like the dewalt or similair I think.

Post Sat Jun 19, 2004 9:25 pm 
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kkeerroo
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Joined: 17 Jun 2004
Posts: 1459
Location: Brisbane


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I disagree with Brett on the Chinese issue.The company I'm currently working as Cheif Engineer for (its amazing how quickly you get promoted when everyone else quits Confused ) get a lot of castings made in China. In fact thats all we do. I do the drawings and send them to China, they make the tooling, send me a sample, I check it, if its right we give them the go ahead to manufacture them. In the 5 months I have been working there I have rejected 95% of the samples I get sent. I have seen parts that have a tolerance of +/- 0.1mm on a demension get made 20mm under the speicified dimension. I have seen stainless steel grates that arrived in Australia rusty. I haves seen 20 ton of men-hole covers that have the fancy checker pattern on the under-side because the manufacturer didn't understand what hidden detail was. I have seen 30 ton of parts arrive over 3 months with black paint instead of blue paint even though the drawing says blue, and the paint was still wet even after being at sea for 2 months. The previous Chief Engineer went to China and gave lectures to every person on the factary floor on how to de-burr parts and I still had to spend 5 hours de-burring the same parts 6 months later. And I could go on.

Sorry for being off topic, but I get really amazed at what those "Sanyo's" can do.
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Post Sat Jun 19, 2004 9:45 pm 
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Spockie-Tech
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Joined: 31 May 2004
Posts: 3160
Location: Melbourne, Australia


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ah yes, I didnt say anything about qaulity though.. Cool.
just that they know how to make things *cheap*.

I have dealt with them too in various phases of my job. I've found them to be keen, hard workers with very little understanding of the whole concept of quality.. Rolling Eyes I guess the old saying still rings true.

good
fast
cheap

pick any *two*

Post Sat Jun 19, 2004 10:02 pm 
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Ajax
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Joined: 17 Jun 2004
Posts: 298
Location: Sydney


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no problem 'teamvertex'.
I am looking in to coming to sydney. thinking of taking a holiday at the same time. Just working out what I need to get arranged to get to the event as I will be flying.
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Post Sat Jun 19, 2004 10:03 pm 
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