Chain Bar Problem

I have been working a lot on chain bars lately. One problem I have been having is that the chain is bending the hopper connection point. See the pictures below.

http://team323z.weebly.com/uploads/1/0/0/6/10062475/6597_orig.jpg

http://team323z.weebly.com/uploads/1/0/0/6/10062475/1811244_orig.jpg

http://team323z.weebly.com/uploads/1/0/0/6/10062475/6393096_orig.jpg

Anyone have any idea on how to keep it so it doesn’t bend? Everything is spaced perfectly, so that shouldn’t be a problem.

XD i would say after you put the other side on you wont notice much difference. just get some good structure like connecting the other side of the hopper to this side and you should be good.

Does the arm still bend without the chain? It may be that the arm pieces are twisted.

The C-channel is screwed directly to the gear, correct? That will be important in keeping it from twisting.

I would try making the arm stronger by building it out of 2 C-channels instead of a C-channel and an L-channel. C-channels resist twisting a lot better than L-channels.

I don’t see any support between the two sides of your tower. Try putting standoffs holding the tower together. If the whole tower is twisting, you will have other problems down the road, and your arm would certainly benefit from a sturdy base.

If you use larger sprockets, there will be less tension on the chain (if it really is the chain causing the twisting, this will help).

That was what I was thinking. Maybe after I had built both sides, and connected both the sides together, maybe, just maybe it wouldn’t bend.

Yes, a little.

Yes, the C-Channel is directly screwed into the 60t HS Gear.

I was going to try that, thanks for reassuring me to do it :slight_smile:

This is no where near the final product of the tower. It will be supported in many places when we are building our competition robot.

Oh really. I will mess around with that if the other steps fail.

Thanks you!

With this design you will always have a little flexibility but it becomes insignificant when you build the other side and connect them together.

Also any supports across the two chain bars will make it a lot stronger.

OK, great to know!

I had heard that Chain Bars weren’t as strong as other lifts such as 4-Bars, and 6-Bars. Is this true? It appears a little shaky while I am building it, but it still seems reliable.

Thank you @tabor473

Well chain bars are inherently weaker than a 4 bar or 6 bar but if done correctly with the angle piece ,which you have, for extra support on the axle and strong connections everywhere, you can make it so that the difference is insignificant.

So yes it is true but a 4 bar and a 6 bar are significantly stronger (in terms of weight that could be lifted before metal breaks) then they need to be so if done correctly you shouldn’t run into to many problems.

i cant exactly tell what’s bending(whether the axle is lose within the pillow block, your collars arent tight, or just very little surface contact)

But you can try reducing the weight of the hopper connection by swapping it for the 7.5 c-channels/rails(less tension). You can also try adding spacers on the inside of the C channel(should reduce wiggling). You can try building the other side and connect them(hoping for the best). Or add more pillow blocks(the offset ones or the flat ones)

when doing this i would suggest putting a 1 inch standoff of the 2 c channels just becaue when you overlap the c channel the holes doesnt line up perfectly and cause friction on your axle. if you have not put bearings when the axle spins it will make a smaller hole. you could also turn your c channel side ways so that the axle goes through the 1 side of the 1X2X1X35 and you have two supports.
Btw im Rickeh808 From youtube

In addition to the other great suggestions, the 1x5x1 C channel is quite a cantelevered bit of metal. Even when you build out and connect the other side, it may still want to twist about from all that weight far away from the single connection point at the axle.

The further away from the joint you have metal, the more torsional force will be acting on the lower axle. Can your lifted hopper structure be lighter at the top? Youhave some aluminum? Would a 1x3x1 c channel work? Even if you make a nice box, it can possibly turn into a parallelogram on you from the left right twist. Strong connection points for the axle are needed defnitiely but reducing the load is another good strategy too.

It appears like you are maximizing the height of a single bar versus using a 4 bar which cuts the lift height a bit. The 4 bar adds a conection point reducing the load effects to prevent twisting too. But another arm = more weight and more friction too.

Less load to lift the metal of the arm means more sacks it can lift. :smiley: