Ok, this thought came to me this morning after thinking about stuff that happened at Bash yesterday.
After some thinking and about 16 rebuilds of the 03 Bosch gearbox, i realized that a combo between the way the mounts FIRST gave us were designed and the way the gearbox is built ,makes the whole assembly WAY to susceptable to breaking apart.
Like the 02 Bosch, the 03 Bosch had a gearbox was made up of 2 sections. Unlike the 02 Bosch, the gearbox was only held together by 3 little locking plastic tabs…w/ slight force in the wrong direction the front half of the gearbox pops off sending gears flying.
The 2 models of Bosch have the negative and positive aspects such as
02 Bosch
+gearbox was held together better
the gearbox was a pain in the but to reassemble
+ gearbox rarely locked up
03 Bosch
-gearbox fell apart WAY WAY to easily
+the gear box was fairly simple to reassemble, if u knew where the gears went
- the gearbox locked frequently
Keep in mind that I’m just speaking from my experience w/ both Bosch motors…but given that experience i greatly prefer the 2002 Bosch.
So now that Ive stated my thoughts i was wondering what the rest of u thought bout the 2 different models of Bosch gearbox/motor.
Although I haven’t used them, from what I have seen at competitions the 2002 and before bosch drill motors are better than the 2003 ones. The 2003 ones overheat faster than the 2002 ones. We were running one of our old bots that uses he 2002’s for about 10 minutes, ad they still werent all that hot. From what I hear, you can’t even run the new ones for a whole match before they overheat.
I say the old ones are better.
and they arent THAT hard to take apart and re-assemble
Your gearbox fell apart repeatedly because of being poorly mounted on the robot.
Bad Things ™ happen when you sideload the motor’s output shaft as you did. I think it was less a function of how the gearbox was designed or assembled and had more to do with the application.
Treat the motors right nice and they will treat you nice. And I don’t mean you have to drive like you are on fluffy clouds. Just never drop them and don’t modify them and don’t slam them from full throttle one direction to the other direction. Mount them well and gear them well and they are an excellent motor. Think about this: How many people ever take apart their bosch drill to take out the pins in the gearbox or to modify the shifter. None. What happens? The drill lasts forever. The thing is just not made to be taken apart. So, if you just trust Bosch engineering and don’t srew around with it, you won’t have any drill problems. If you take it apart a first time, it will take itself apart the next time. If you just used it like you got it, it wouild have been fine.
Now, maybe you never did open your gearboxes before you had any problems. Then, I would attribute the problem to improper mounting, gearing, or alignment.
I just fail to see how my team had the Chias coupled right to the output shaft of the drill and we used the provided mounts and couplers and we had horrible alignment but never ever had any problems. We were crashing and shoving and flipping other robots all over the place too.
If we do get the same motors next year year here are couple tips that work: you can lock the shifter into place with a single zip tie around the body of the gearbox just fore or aft of the shifter. Also, nearly all teams have complained of overheating. All but the “fluffiest” driving will cause this. Do yoursef a favor and invest in some heat sinks and you will never have any problems with overheating again. Let me know if you have no idea where to get them and I’ll tell you. If installed properly, you won’t even need any fans.
I’ll probly be the first person to point out that the overall positioning and overall design of the arm(on my teams robot) wasnt the greastest design.
there were alot of things we could have done different if we had the time, and i definatly agree w/ wut sanddrag said “If you take it apart a first time, it will take itself apart the next time.”…Definatly true.
and as for things like to much force the wrong and such, my team was very careful not to have to much tension on the chain and to avoid sideways force on the gearbox where possible. just based on my teams experience w/ both motor i still greatly prefer the 02 bosch
Yes, it is very true that no matter how hard you try, if you take them apart or they come apart, they will not go back together exactly like they came from the factory.
My team has had good luck with the 03 drill motors/gearboxes. Yes, we took the pins out, and then we had the problem of the front half removing itself. Solution? Weld the clutch disks together and remove the spring tension going through the twist-lock that holds the front on. We never any problems after we did that. I know that team 1151 also put three little set screws though the twist lock joint, and didn’t have any more of those problems again.
I dont get what all you people have done wrong to make the drills have so many problems. We modified them by removing the clutch and the pins, and we never had a single problem. The one problem we did have was with the mounts that were trash in my mind for anyone but a team that doesnt have the machining capability to make their own.
Yes, they did have over heating problems, but this years drill was more powerful than last years, so that is to be expected. We ran our motors under full load for a good 5 matches in the finals at Cal Games yesterday with 15 minutes or so between matches, and even 5 minutes in the finals, and they got hot, but not too bad. Cooling spray works pretty well, and heatsinks are even better.
The positives definitely outweigh the negatives, Id take this year’s drills again any day.
One thing to remember is that before this year we were given the housing that was designed to hold the motor and clutch. This past season the mounts that teams were given were not designed the same way as the previous years. My feeling is that we should be given the original housing because that holds the assembly together better.
The new bosch motors and gearboxes were very tricky to fit into the mounts right so my guess is that more than a few teams got it wrong and probably didn’t even know it. If you install the assembly into the mount correctly, it shouldn’t give you any problems. We took the time to make sure they went in right and have had no problems since.
My ONLY gripe about the new ones is that the black plastic endbell holding the brush hoods is very thin in a couple parts and can easily break without properly supported wires. The wires tend to pull on the endbell flexing it greatly and eventually breaking it. However, we put a blob of epoxy on each area and made a wire mount to tie our giant 8 guage leads to. Again, no problems.
The 2002 drills’ clutches slipped A LOT easier on full setting. This past year, we left the clutch just as it came and (as in 2002 testing) and put it on the highest setting and it never slipped once.
if i remember correctly from 02, my team fixed the prob of the bosch 02 clutch slipping by putting setscrews in. I dont remember exactly how it was done b/c i have worked w/ those in about a year, but it worked very well, and we never had a prob w/ the clutch slipping.
and sanddrag…im a little confused. wut do u mean by “endbell”, and why did u use 8 gauge leads on the motor?
The endbell in the back of the motor made up mostly of black plastic. The endbell contains the brush hoods, the brushes, the springs, the places to solder the power wires, and the bearing for that end of the armature.
We too put setscrews in our 2002 gearboxes so they would’nt slip. It did work very well. The thing is, we didn’t have to with the '03 ones. If I remeber correctly, you would remove the clutch assembly and outer plate. Then dump all the balls out. Then tap the holes the balls were in for an M6 (?) thread. Then insert the setscrews into the tapped holes and they would press on the inner clutch plate preventing it from slipping.
As for us using 8 gauge wire on the motors, they pull a lot of current so we didn’t want the losses of resistance, we already had enough losses due to friction and binding. As a general rule, my team uses high quality finely stranded wire, one size larger than what FIRST requires for everything. Likewise, we used 4 gauge from our battery to the main breaker and to the maxi block and 6 guage from the main breaker to the little fuse block.
4 gauge wire from batt to main breaker, dont u think thats a little extreme? Not to mention probly a pain to work w/
I can understand being worried bout the losses of resistance if u are working w/ somthing that needs a certain range of resistance to work, but this is a robot not some sort of sophisticated industrial equipment.
when u actually figure it out the losses in power/ supplied current is very small. http://www.paigewire.com/copperAWG.htm
i mean FIRST regulates that we use 6 or 8 i believe from the batt to main breaker. Lets say 6 for arguments sake and if u figure out the resistance of the wire based on that ur talking about one ohm per 2,000 feet. So in my mind theres not much to worry about unless ur have a major problem w/ the wire overheating to the point where the insulation might melt and cause problems.
So why waste the weight using larger wire? thats jus less weight that u have 4 the rest of the bot. w/ the battery counting in weight (as of now) we only have 117pounds to play w/ in terms of robot weight, so why waste weight on needless wire?
I know this is getting off topic, but many teams use monster cable on their robots. I know it sounds crazy, but monster cable is easier to work with because its finer strands. Any yes 4 guage wire is heavier, but its only got about a foot to travel?
While I wasn’t exactly around our pits much, (too busy inspecting or helping other teams) I don’t recall hearing about any problems with this year’s motor and gear box from our pit crew. We replaced the output shaft with a custom version and somehow locked the clutch. I think we used the method in Dave Lavery’s white paper. We also used the “stock” mounts but mounted them on a sub-plate to allow for our shifting mechanism.
We replaced the wires before we got the word not to, but the guy who did it solders for a living, so we got away with it. It took one look for us to figure out that was going to fall into the “skilled labor” catagory. We did not change the wires on our spares.
Over all I think we liked this year’s motor better, but it certainly is more finicky. One of our rookies had a damaged motor when it came out of the box. The keys are pretty simple:
Protect the end bells from damage at all times
No cantiliver shafts. All shafts need to be supported on both ends.
Make sure your drive train runs true and you pick your gearing appropriately. Unnecessary drag from misalignment or working your motors too hard by gearing too high can both cause overheating.
Make sure the motor is installed properly in the mount, and the gearbox is installed properly on the motor. There is a right way and a wrong way to install them. The right way works much better. But the wrong way isn’t obvious. If the brushes are parallel to the bottom of the stock mount, you did it right. If not, you might want to do something about it.
As an inspector, or just running around helping teams, the wrong way motor was something I looked for. Correcting it was not a requirement, but it did seem to solve an awful lot of drive train issues. There were almost as many teams with mis-installed motors as there were missing numbers. I think the installation instructions could have been alot more clear on this point, either that or the hardware could have been more confusion-proof. I didn’t say fool proof because in most cases it was simple confusion, most fools stay away from FIRST.