pic: DeWalt drive base: side module

[Richard McClellan]

that's pretty cool....I'm curious though....what kind of interface shaft do you have to connect to the end of the dewalt for the direct drive setup?

[dbell]

Originally Posted by richardmcc2

that's pretty cool....I'm curious though....what kind of interface shaft do you have to connect to the end of the dewalt for the direct drive setup?

The shafts that go between the 2 red plates and hold the wheels are .75:" thick. In the end of those there is a .5" threaded hole. The DeWalt will screw into the end of the shaft. Then i will drill a hole through both shafts and put a pin through. Hopefully this will be solid and strong.

[newton418]

Originally Posted by fimmel

also in team 885's experience the dewalts dont shift at exactly the same time.. this would cause binding as far as i know. out solution was to only use 1 dewalt/cim per side.
...just a thought
...forest

Though I'm sure there are minor differences in the shifting times, we've never had a problem running 2 DeWalts on one side, connected by chain. Perhaps we weren't pushing them as much, it's definitely doable to have 2 DeWalts on one side of a drive train.

[fimmel]

Originally Posted by newton418

Though I'm sure there are minor differences in the shifting times, we've never had a problem running 2 DeWalts on one side, connected by chain. Perhaps we weren't pushing them as much, it's definitely doable to have 2 DeWalts on one side of a drive train.

its cool to hear someone who has done this successfully.... we never did try linking 2 together but we were cautious. ill tell our head engineer about this since it makes my job as a part designer easier.

...forest

[AdamHeard]

Originally Posted by dbell

The shafts that go between the 2 red plates and hold the wheels are .75:" thick. In the end of those there is a .5" threaded hole. The DeWalt will screw into the end of the shaft. Then i will drill a hole through both shafts and put a pin through. Hopefully this will be solid and strong.

3/4" diamater shafts will definately be strong enough; especially if they are steel. Depending on the size of the pin you're putting through, aluminum should be just fine. Either way, 3/4" is kind of heavy though. I guess you don't have much of a choice w/ the current interface with the dewalts though.

[Madison]

...

[Greg Needel]

Originally Posted by AdamHeard

3/4" diamater shafts will definately be strong enough; especially if they are steel. Depending on the size of the pin you're putting through, aluminum should be just fine. Either way, 3/4" is kind of heavy though. I guess you don't have much of a choice w/ the current interface with the dewalts though.

[note] this is not picking on adam I am just using it as an example [/note]

There are alot of things that go in to the"strength" of a material in an application. Just saying that it will be strong enough shouldn't really cut it when contributing to a design.

As an example when you are talking about strength it is obvious that you are referring to not failing during application, but in what ways is the part strong enough. Are you concerned with the torsional strength to make sure the shaft wont twist off? What about the bending stresses of this kind of loading And don't forget to take into account the stress concentrations caused by the pin slot and the fatigue strength due to alternating loading...What about the shear strength of the pin itself?

I guess my point is there is alot more that should go into the design of a system like this, and just making wild guesses could cost you in the end. If you under design something you can get a failure and if you over design you have wasted weight and real estate for this mechanism.

Now I realize that 95% of the teams out there probably don't do/ know how to do any of this math and just throw stuff together (I know I have fallen to the same fate from time to time) but in the off season when we have plenty of time for this kind of top level design. I urge everyone to open a book or ask someone who knows for help on these problems rather then taking the "backyard engineering" approach and just winging it. Same goes for those offering suggestions on design to be able to backup your suggestions with some theory. Remember there are teams who live and die by the advice given on these boards and you want to make sure that they are given correct information.

[AdamHeard]

Originally Posted by Greg Needel

As an example when you are talking about strength it is obvious that you are referring to not failing during application, but in what ways is the part strong enough. Are you concerned with the torsional strength to make sure the shaft wont twist off? What about the bending stresses of this kind of loading And don't forget to take into account the stress concentrations caused by the pin slot and the fatigue strength due to alternating loading...What about the shear strength of the pin itself?

Looking at the amount of torsion put into the shaft (I just ran some similar calcs yesterday for a 1/2" shaft ) that shouldn't be the problem, What I was reffering to was that the point of failure will probably depend on the pin (either the pin itself, or the shaft where it engages the pin).


With so much time on your hands, and since you already modelled it anyway, you my as well learn to use the stress analysis built into inventor to check your it. I've been using this all season on critical parts and it has never failed me (remember to build in a safety margin).