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Drill gear case modifications.
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Totaly_Recycled
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Drill gear case modifications.

Hi all
I have been modifying battery drill gear boxes and am thinking of doing these for any one who wants them .
The main modification is rebuilding the second stage gear carrier and puting in bigger dia pins and a carrier plate on the top side of the gears that hold all the pins together .I have also added 3 more pins inbetween the gears that hold the main gear carier and the plate together.The bigger dia pins take out all the slop that is now present in the gears.

So for one pin to bend and break all 6 pins have to bend.
I am also putting metal gears into the first stage and putting the bigger dia pins in them .A small sleeve is cast into into the inside bottom of the gear case to take out the slap of the ring gear that ocurs with the grub screws .This will remove all the back lash and hopefuly help to stop things geting broken.

The bigger dia pins take out all the slop that is now present in the gears as well.

The second mod is to strengthen the plastic gear case its self .
I have built a mould which incorperates a mounting plate that will do away with makeing motor mounts .It will be held on by four evenly spaced bolts.

The castings are made from polyester resin reinforced with chopped fiberglass.

Here is a low res pic of my hand made proto type that i have now made a reusable mould from .

http://robowars.org/forum/album_pic.php?pic_id=856

Post Tue Jun 07, 2005 10:32 pm 
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Philip
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That gearbox support looks good. I will be interested to see it up close.
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Post Wed Jun 08, 2005 10:08 am 
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original_carnage
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what kind of $$'s do you think ???

hell yeah, I'm interested..
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Post Wed Jun 08, 2005 2:34 pm 
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Totaly_Recycled
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At the moment im makeing a few to put into a test bed and give them a good test to see how they handle geting thrashed . So far the one i moded in Sproing is going good .I havent tried any with the mounting plate yet .Im hopeing that the 6 mm thick fiberglass reinforced resin is strong enough for the mounting plates. my main concern will be how they hold up around the bolt holes .I was goign to cast an aluminium plate on the top of them but decided against the extra seting up at the moment .I think as long as they arebolted with a reasonable thicknes flat washer under the bolt or nut holding them on they should be pretty tough.

Post Thu Jun 09, 2005 7:23 pm 
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Totaly_Recycled
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Ive just done some measurments of the moded drillcases . they have base foot print of 75mm wide x 50 mm deep

The holes are spaced 25mm(Center to center )apart on each side and center in 8mm from the edge of the mount and 10 mm from the front of the mount

Height from the highest point of the gear case to the botom of the mount is 53mm .
The mounting plates are 12mm wide on the top measured from the edge to the start of the radius.

They are 20 mm wide on the mounting surface side .

I havent had one weighed yet with the full mods but i will post the weights when i get them done . At the moment i havent worked out a price for makeing them .

Post Thu Jun 09, 2005 8:37 pm 
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Spockie-Tech
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Once you get them all sorted and are happy to start selling them, you should do a contra deal to get Aaron (or maybe Glen or the Kero's (if aaron doesnt have time), since they're the CAD guru's) to make up a 3D cad model of them..

It would help builders plan to use them as well as being good advertising for them, and who knows, they might even sell overseas if they prove to be good, since there's nothing like it commercially available that I know of..

Keep us informed as to how the testing is going..
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Post Thu Jun 09, 2005 8:55 pm 
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Knightrous
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quote:
Once you get them all sorted and are happy to start selling them, you should do a contra deal to get Aaron (or maybe Glen or the Kero's (if aaron doesnt have time), since they're the CAD guru's) to make up a 3D cad model of them..


When he's got the first one he's happy with, I'm happy to draw it up Smile
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Post Thu Jun 09, 2005 9:19 pm 
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Totaly_Recycled
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yes might do that but im sure Aaron could nearly draw them from tose measurments i just havent given the rear dia or the front as its all sort of tapered one way so it can come easily out of the moulds
just basicly add about 3mm of thicknes to the origional cases at the rear tapering down to the squared front

Post Thu Jun 09, 2005 9:27 pm 
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Spockie-Tech
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Its more the mounting bolt-hole spacing, axle height, and things like that I was thinking of, plus of course the fact that the CAD render would look cool as a promotional thingy for them..

Of course the number of builders who actually build their robots from a CAD drawing is relatively low (In Australia at least), but being able to just virtually glue them into a bot design and see how much of an improvement they make in mounting simplicity would probably help sales overseas where more people do the CAD thing..
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Post Thu Jun 09, 2005 9:54 pm 
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kkeerroo
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So thats one mount to hold in a motor. Thats interesting.

Is Brett talking about a 2D promo drawing? I did 72 of those in 7 days. Let Aaron do it.
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Post Thu Jun 09, 2005 10:13 pm 
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Spockie-Tech
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Sounds like you've been busy there.. 72 in 7 days ?! Shocked I'm sure you're sick of it..

a full 3D model would probably be better for potential customers to fiddle with, but if Andrew wants to sell them, then a 2D image would obviously be required for a web page.. maybe a photo would be sufficient for that, but a CAD render to go with it would be more vivid..

Actually, Mr Kero's just reminded me of a thought I had that might be worth adding to your custom mold if its not too hard to do..

Some form of protrusion from the gearbox casing that extends backwards underneath the motor can that can have a cable-tie, hose clamp of other clamping system put around it to offer support to the motor might be a valuable addition.

If you are carrying the whole motor weight supported only by the 2 little screws that hold the front of the motor can to the gearbox plate, then under heavy shock loads (or "jolts" Laughing) the motor might seperate from the gearbox. Tieing them together in some way should help that
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Post Thu Jun 09, 2005 10:39 pm 
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Knightrous
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http://www.robowars.org/forum/album_pic.php?pic_id=888
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Post Fri Jun 10, 2005 1:24 pm 
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Philip
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Very well done, Aaron. The ways of CAD are a mystery to me.
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Post Fri Jun 10, 2005 1:53 pm 
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Totaly_Recycled
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Thanks for your comments Brett and others .
Yes i was thinking of a motor suport but doing it in the same casting is tricky and it would also get in the way of puting the gear box in .
I have discused it with Arron and i will be looking at a seperate casting that slides over the motor from the rear with a mounting plate that slides in on top of the gearbox foot plate's and would be drilled to take the same bolts .

So far all my mounts ive made from ali havent suported the motors and so far none of them have broken lose from the gear cases .But yes there is a lot of overhang on the two screws holding them on .Haveing a suport that is mounted on the same suport as the gear box will be much better than a seperate suport on to the chasis as if the gear case gets moved and flexes the motor will move with it instead of it being solid and putting presure on the gear case .Thats one of the reasons i have never put a seperate suport on our motors .

Aaron will put up some 2 d versions with measurments when he gets the time .A big thanks to Aaron for doing that 3 d render so quickly . He has drawn it to scale so shouldnt take long to get the 2d's and measurements from it .

Post Fri Jun 10, 2005 3:54 pm 
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Totaly_Recycled
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Ive come up with an idea that might work as a motor suport i will have to make it out of something soild or try and explain it to Aaron to draw ..might be easier if i make one first .
It will basicly be two plates that bolt on to the feet of the new gear box mounts. They will then extrude back and inwards towards the motor and then have a 2 to 3mm thick aprox 25mm long tube cast between them which will be about 5mm bigger inside dia than the out side of the motor can .

This will allow for different sized motors to be used . To fit the motor suport case to the motor will be a simple matter of lightly oiling the motor can then slide the houseing extension over the motor and bolt it to the gearbox mount.
Once bolted on, a bead of silastic can be squeezed into the gap between the motor can and the extension tube and allowed to set .The excess can then be trimed for neatness.
This will ensure a fully suported motor with no stress on it.
The silastic will hold it tight but still allow a bit of shock absorbtion or miss alingment .

By oiling the motor before hand should allow it to be removed from the mount if the motor ever needs replaceing.
Does any one see any flaws in this concept except for the litle bit of added weight ?

Post Fri Jun 10, 2005 9:27 pm 
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