2583 Off-Season Drivetrain Help

[Feroz1325]

It looks like you are going with a live axle system to transfer the power, however i do not see bearing in the aluminum extrusion. If you do not put bearings the abrasion of the shaft rubbing on the profile of the hole will damage both the metal and the shaft.
Also in a live axle system you will need hubs on/in the wheels rather then the bearings (i think) you have currently.
Also you may want to add another corner gusset on top.

Excellent first CAD, i look forward to seeing great things in the future!

[ferrari77]

Originally Posted by Feroz1325

It looks like you are going with a live axle system to transfer the power, however i do not see bearing in the aluminum extrusion. If you do not put bearings the abrasion of the shaft rubbing on the profile of the hole will damage both the metal and the shaft.
Also in a live axle system you will need hubs on/in the wheels rather then the bearings (i think) you have currently.
Also you may want to add another corner gusset on top.

Excellent first CAD, i look forward to seeing great things in the future!

After looking more closely I see the problem in my CAD
I have never dealt with hubs separate from the pulley because our team has always chained our drivetrains with the sprocket directly attached to the wheel

The pulley is attached to the axle with a set screw so they will spin together
How would I go about connecting this wheel to the axle so they spin together?

I looked at Andymark's website and found these hubs
http://www.andymark.com/Hubs-s/215.htm

Most of them used keyed axles and we do not have the resources to machine a keyed axle, can you buy those?

[MichaelBick]

Yes, you can get keyed axle from many sources. Mcmaster is a fine source to get keyed axle if you don't need much bulk. Because you said that you have a lathe, I highly recommend hex axle though because it makes assembly easier. Andymark sells both hex bearings and hex hubs. West Coast Products sells colson hex hubs and 1/2 undersized 7075 hex.

[ferrari77]

I made the pulleys have a hex bore and attached a hex bore hub to the wheel so they will spin with the axle

Now how do I deal with the axle going through the frame right now with no bearing?

I thought about using a bearing hub and mounting it to the side of the aluminum channel but the axle is now a hex axle and I cannot find bearings that fit hex axles

Any thoughts on how I fix this?

[Gregor]

Originally Posted by ferrari77

I made the pulleys have a hex bore and attached a hex bore hub to the wheel so they will spin with the axle

Now how do I deal with the axle going through the frame right now with no bearing?

I thought about using a bearing hub and mounting it to the side of the aluminum channel but the axle is now a hex axle and I cannot find bearings that fit hex axles

Any thoughts on how I fix this?

Honestly there have been quite a few links to andymark already. They sell hex bearings. Go and look.

[ferrari77]

I have included a link for the .step file of the chassis now

I included a lot of the changes you guys suggested

I still have to include the rest of the electronics and figure out a tensioning design but that will come later

The red things on the wheels are the colson live axle hubs
http://wcproducts.net/wcp-00053/

The blue things on the aluminum channel (seen from the bottom of the robot) are AndyMark hex bearings with flanges
http://www.andymark.com/product-p/am-0279.htm

The hole in the aluminum channel is slightly smaller than the OD of the bearing so they will be pressed in and there is a small flange on the bearing which will keep it from going too far.

Also the axle is now hex and the pulley has a hex bore so they are connected

Do you guys have any more comments or suggestions?
Your help has been very useful so far, im learning a lot

Download Link:
http://www.2shared.com/file/kdrucknG/chassis1.html

[Garret]

I think this is much better.

However a few things I notice:

• Is there a reason you have the large plate on top of the frame rather than below it? If there isn't a reason, you could probably move it below and protect the electronics a little easier.

• I would recommend that you try to support the gear box output shaft on the end.

• I would also only make the shafts 1/2" hex at the wheel. By turning it down to regular 1/2" you save yourself the need to purchase a broach. Additionally you can save money by purchasing regular 1/2" bearings ($7 vs $9.50) rather than hex bearings.

Again, this design is much better now, good job.

[ferrari77]

Originally Posted by Garret

I think this is much better.

However a few things I notice:

• Is there a reason you have the large plate on top of the frame rather than below it? If there isn't a reason, you could probably move it below and protect the electronics a little easier.

• I would recommend that you try to support the gear box output shaft on the end.

• I would also only make the shafts 1/2" hex at the wheel. By turning it down to regular 1/2" you save yourself the need to by a broach. Additionally you can save money by purchasing regular 1/2" bearings ($7 vs $9.50) rather than hex bearings.

Again, this design is much better now, good job.

Would it make it the structure stronger if I put the board below or is just for the sake of protection? I could definitely put it below if its better

I thought about doing this for the axles but we only have a lathe and I dont think we have any tools to turn a round axle to a hex axle
Mcmaster sells hex axles which are long enough but the hole axle is hex

Is there a way for us to make the part of the axle hex without buying anything?

[Garret]

You can buy 1/2" hex shaft and turn it down to just regular round 1/2" shaft with a lathe its a pretty standard operation. You would then just use either set screws or cotter pins for the sprockets.

Putting the plate on the bottom of the frame is what is normally done. In my opinion it looks cleaner, helps lower the Center of Gravity, and allows you to attach a superstructure easier.

[Mk.32]

Originally Posted by ferrari77

Would it make it the structure stronger if I put the board below or is just for the sake of protection? I could definitely put it below if its better

I thought about doing this for the axles but we only have a lathe and I dont think we have any tools to turn a round axle to a hex axle
Mcmaster sells hex axles which are long enough but the hole axle is hex

Is there a way for us to make the part of the axle hex without buying anything?

A. WCP is selling hex bearings for $7.5.
B. You can turn hex into round shaft with a standard lathe that has a 3 jaw check and just HSS tool. Also the hex pushing up against the bearing would help retain the shaft in place

[z_beeblebrox]

I'm not really a drivetrain expert, but maybe you could save some weight by cutting a lightening pattern into the electronics board.

[ferrari77]

Originally Posted by z_beeblebrox

I'm not really a drivetrain expert, but maybe you could save some weight by cutting a lightening pattern into the electronics board.

I've been waiting to do this because our team does not know if we will have access to a laser cutter
If we do I can do a cool looking lightening pattern with diamonds and triangles
If not I will do what we have done in the past with just rows or circles

[MichaelBick]

I also recommend a garolite bellypan if you aren't able to get a bellypan lasered.

[karomata]

I would use chain instead of pulley belts, they don't slip as much and are more reliable.

[Gregor]

Originally Posted by karomata

I would use chain instead of pulley belts, they don't slip as much and are more reliable.

Really? How do you know? What do you mean by "don't slip as much," and why are they "more reliable?"

There is no defined better in terms of chains or belts.