Low Cost Planetary Gearbox Source...

[Matt Adams]

Originally Posted by Evil Robotics

Any recommendations on which modified dewalts and where can they be purchased?

You can read the whitepaper here:
Nothing But Dewalts

And read the discussion here:
Nothing But Dewalts

It's among the most well written whitepapers on CD. Where you can purchase the components are well documented.

Matt

[Chipawa]

We want to try out the Banebot gearbox. What advice can you all give for mounting the new pinion on the Fisher Price motor shaft? Is it simply a matter of pressing the new pinion on the shaft? I'm thinking there must be more to it than that. And what tools would you recommend for the job?

-Chip Tucker

[Justin Stiltner]

Chip,
Having done this just this weekend I can tell you what I did.

You will need to pull or otherwise get the pinion off the FP motor, I had to grind ours down a bit to fit into the puller that we got from bane bots. DO NOT GRAB IT WITH PLIERS AND TRY TO PULL IT OFF, YOU WILL DESTROY THE MOTOR because the force you are putting on it will be transfered to the bushings, etc. in the motor.

After you have the pinion off the FP motor take apart the Planetary 4 screws in the face, and 2 on the motor, careful the entire thing will fall apart.

Now would be a good time to wrap the FP motor with masking tape, this is to keep the metal bits and shavings out of the motor, and yes they will get in there no matter what you try so go ahead and wrap the whole motor, leaving only the shaft accessible.

Carefully measure the length of the shaft on the motor that came with the planetary and carefully mark the FP motor shaft the same length and with a dremel (I tried a band saw, didn't work too well, very dangerous, don't do it) and cutoff disk carefully and very accurately cut the shaft of the FP motor to length being very careful not to heat the shaft up too much as you do. I didn't have a problem with the shaft spinning, but if you have this problem you could hold the back side of the shaft with pliers THROUGH the masking tape. After cutting measure the shaft again, as you don't want to have to pull the pinion off to shorten the shaft more later.

Blow or vacuum the residue off the motor.

Take a file and bevel the edges of the cut edge on the shaft and make sure there are no burrs sticking up from the end, It should be a clean cut. DO NOT FILE OFF THE SPLINES ON THE SHAFT only bevel the end and dress the cut.

Clean the motor off, leaving the masking tape on blow or vacuum the shavings off the motor can and wipe down with a clean paper towel, etc to make sure they are gone.

Take your new pinion(only about 1$ when you order the transmissions) and place your motor in an arbor press (a GOOD vice MAY work if it had smooth jaws and very little slop) making sure that the only contact point on the back of the motor was the shaft, not the plastic or the electrical contacts. Keeping the motor and pinion very straight press the pinion onto the shaft, if it looks crooked stop and look very closely, if the assembly cocks in the press then you could bend the shaft and destroy your motor. I had to stop 3/4 through the pressing and remove shavings from the pinion end to allow further pressing. The pinion should be flush with the end of the motor shaft.

Clean the motor off for the last time and carefully peel the masking tape off (our team leaves the tape over the cooling holes in the motor until just before ship just in case) and reassemble the transmission cleaning the screws off(or replacing with socket head cap screws) and lock tite-ing them. If the end blocks don't seem to be seating onto the round center section or the transmission doesn't turn, or is harder to turn than with the other motor your motor shaft may be too long and need to be shortened. If that happens don't forget the tape!

Hope this helps, and if anyone has a better way feel free to chime in

[petek]

Ditto for Justin's post, plus a warning: I'd say the outfit in China which makes these puppies has the same material quality control we've all come to expect for inexpensive hardware coming from that part of the world. Even taking great care, I managed to strip the threads when tightening two of the screws holding the gearboxes together. If we use it, we'll be putting heli-coils in.

[Joe Johnson]

Originally Posted by petek

Ditto for Justin's post, plus a warning: I'd say the outfit in China which makes these puppies has the same material quality control we've all come to expect for inexpensive hardware coming from that part of the world. Even taking great care, I managed to strip the threads when tightening two of the screws holding the gearboxes together. If we use it, we'll be putting heli-coils in.

I was unhappy with the use of phillips head screws rather than torx or socket cap screws. I don't have the screws in hand right now. Does anyone know the thread definition? Based on my memory, I think it was an M4 or perhaps it is a 10-32 (based on the fact that the rest of the metal mounting points are that thread).

If you know, please share.

I think if I were using these gearboxes, I would replace the phillips head screws with a hex socket head cap screw (though I don't know if I would go so far as to install helicoils on any threads as a preemptive measure).

Joe J.

[Greg Needel]

i would say for us so far the hardest thing about these trannies is getting the gear off the FP motor. I ended up chucking it up in the mil and milled the gear of. As for pressing the new pinion to the shaft we haven't done it yet. But the plan of attack is to make a spacer from the motors that come with the transmissions that fits between the pinion and the motor casing, then use that same spacer on the FP motor. We are planning to heat up the new pinion and thermally bond it onto the shaft so there is less of a chance of bending the shaft on the FP while applying it. I will write up an after thoughts post after we are done.

[Peter Matteson]

Am I the only one that that the pinnion gear split when I pushed it onto the FP shaft?

We tried to use one of these on a mechanism and after I pulled the gear off the FP (using a bearing seperator and drive pin punch on an arbor press) I went to install it on the FP motor. I did not do anything to the splines but instead tried to press the gear straight on and heard the dreadful pop of the pinnion.
Pete

[petek]

Originally Posted by Dzdconfusd

Am I the only one that that the pinnion gear split when I pushed it onto the FP shaft?

We tried to use one of these on a mechanism and after I pulled the gear off the FP (using a bearing seperator and drive pin punch on an arbor press) I went to install it on the FP motor. I did not do anything to the splines but instead tried to press the gear straight on and heard the dreadful pop of the pinnion.
Pete

I turned the splines down to about 0.126 because of the high interference - I was kindof afraid of the brass pinion doing something like that. The splines bring the OD out to about 0.130, while BaneBots says the pinion is for a 0.125 shaft OD.

[Alex Golec]

Originally Posted by petek

I turned the splines down to about 0.126 because of the high interference - I was kindof afraid of the brass pinion doing something like that. The splines bring the OD out to about 0.130, while BaneBots says the pinion is for a 0.125 shaft OD.

What methods has anyone used for turning down the motor shaft?

_Alex

[dtengineering]

Originally Posted by Dzdconfusd

Am I the only one that that the pinnion gear split when I pushed it onto the FP shaft?

We tried to use one of these on a mechanism and after I pulled the gear off the FP (using a bearing seperator and drive pin punch on an arbor press) I went to install it on the FP motor. I did not do anything to the splines but instead tried to press the gear straight on and heard the dreadful pop of the pinnion.
Pete

Ours broke, too.... didn't even notice until we powered it up... it lasted about 3 seconds. Great little gearboxes, though... we'll buy some more pinions, though.

Jason

[Joe Johnson]

I am continually impressed with the Folks at Banebots, Inc.

I have been bringing up concerns and problems and they have been very pro-active in their response.

This is a copy of the latest letter from Ed Yackey concerning the screw threads stripping out:

oe,

This is what we have for screws:

The thread is M3, Pitch: 0.5 mm
The head diameter can be at most 5.5mm
Stage Length McMaster#
1 20mm 91290A123
2 30mm 91290A130
3 35mm 91290A135
4 45mm 91292A025

We have ordered the 20mm, 30mm, and 35mm screws from McMaster and verified
that they are a good replacement. We have not checked the 45mm screws
from McMaster but believe they should work.

The back plate on the gearbox (between ring gear and motor) is fairly
thick and the holes are drilled through and fully tapped so the lengths of
the screws are not real critical. The 35mm and 45mm screws for the 3 and
4 stage gearboxes could be longer if you wanted more threads in contact.
In particular the 35mm screw is a bit short and it looks like the
manufacture removed the lock washers from these screws to compensate.

The heads of the screws need to be max 5.5mm. The McMaster socket head
screws listed above just fit.

The screws which mount the motor to the gearbox are M3, 8mm long (McMaster
#91290A113). We have purchased these screws from McMaster and verified
they work.

We would like to offer free replacement screws to all FIRST teams which
purchased gearboxes. What we’d like to do is to have any team that wants
new screws send as an email with the invoice number on it. We can then
look at what they ordered and send then the correct screws. I’m guessing
posting on the FIRST forum is the best way to announce this. We have a
limited number of screws in house now and are expecting a good supply next
week.

Thanks for you help

Ed Yackey
BaneBots, LLC

I think that this is a very reasonable response.

Please continue to keep us posted with your experiences with these gearboxes and this company.

Questiong to the CO teams & FIRST folk: Banebots, Inc is in Fort Collins, how come you guys have not been beating on their doors and getting them involved? We have to find a way to get them to the Denver Regional.

Joe J.

[Greg Needel]

That is a very generous offer. Just for general note, we bought the 20:1 gearboxes and i replaced the screws with M3- 30 cap screws. I did have to turn the heads on them down a bit to get them to fit into the clearance holes but after that the snugged right up no problems. I Would recommend that if you haven't taken them apart yet make sure you do it with a proper sized Phillips screw driver, this will help prevent stripping until you can change the screws.


Some other assembly notes i have found through experience:

The spacing that you want from the pinion to the motor body is about 1/16 of an inch, making a spacer plate really helps with the assembly.

you can head the pinion to make it side on but after trying that pressing it is much easier.

when you press it on only support the motor on the shaft, bend the electrical leads out and hold it between the 2 ends of the shaft, this minimizes the chance of bending the shaft. I used a socket for a spacer.

If you have old FP motors lying around make sure they are no where near you when you are working. (good thing i bought extra pinion gears.)

If anyone needs help or advice please feel free to contact me. So far i am very impressed with these little gearboxes and i have a feeling i will be using them for years to come.


Greg

[Joe Johnson]

Latest update from Ed at Banebots concerning stock of pinions and pullers. FYI.

Also, teams with experience with these gearbox: Please share the the Good, the Bad and the Ugly with us. We are all learning.

Joe J.

Joe,

Just to give you an update on our stock. The 3.2mm 5:1 pinions for the
36mm 5:1 and 25:1 gearmotors are back in stock. The gear pullers should
be in stock tomorrow (Friday) or Monday at the latest.

Ed Yackey
BaneBots, LLC

[Kevin Sevcik]

Originally Posted by Joe Johnson

Latest update from Ed at Banebots concerning stock of pinions and pullers. FYI.

Also, teams with experience with these gearbox: Please share the the Good, the Bad and the Ugly with us. We are all learning.

Joe J.

The screws holding the gearboxes together were very tight on one of our boxes. Tight enough that when the kids used a slightly ill-sized phillips driver, they stripped the heads pretty quickly and we had to drill them out. For those that are curious, they are 3M metric screws, and I believe about 28mm long on the 1:16 and 1:25 gearboxes.

[jonboy]

Just got our Banebot transmissions and noticed that the air duct of the motor near the output shaft is blocked by the Banebot transmission. The FP plastic transmission has some holes to i assume let cooling air flow. The question is at what loads and duration at room temperature is this detrimental?