topic Re: Any ideas on a better or cheaper design for this robot spider? in Fusion Design, Validate & Document Forum

Any ideas on a better or cheaper design for this robot spider?

samgaddis — Sat, 09 Feb 2019 17:08:02 GMT

I’m building a ridable robot spider that uses two hand drills for motors. I’m not an engineer by trade, so I’m curious if anyone has a better idea for two challenges I’m facing:

Problem 1 - not a huge one: Is there a better solution to hold the drive shafts in place? Right now I’m using a bearing on the top plate at the bottom near the bevel gear. I have a separate mechanism that holds the drill in place firmly (so don’t worry about that). I think this might actually be a fine solution, but just curious.

Problem 2 - the real issue: more challenging is whether or not there’s a less expensive alternative to the bevel gears to transfer the rotational force of the drill 90 degrees. The gears I found on McMaster are $50/ea and we’d need 4 total. A plywood bevel gear doesn’t seem realistic here since it would be a tricky 3d cut to actually get a bevel, but I could be wrong. What other ways can you turn rotational motion 90 degrees? Worm drive?

Attached is a video explaining the problem. And here’s the link to the model: https://a360.co/2UCrmgz

Re: Any ideas on a better or cheaper design for this robot spider?

TrippyLighting — Sat, 09 Feb 2019 17:40:54 GMT

I'd look for an off-the-shelf right angle gear box. Here is one at McMaster Carr. There are others.

It might be abbot more expansive but you save some headaches. The forces in your setup are not to be underestimated and if Plywood can absorb that is the question. With a gear box it's all internal.

I am very interested in the human model sitting on top of the chair in your screencast . Did you model this, or if not, where did you find it ?

Re: Any ideas on a better or cheaper design for this robot spider?

samgaddis — Sat, 09 Feb 2019 17:47:16 GMT

Good idea. Might be worth it and I can always use the gearbox for something else down the line.

I found the human model in the Fusion 360 gallery though there seems to be some weird bug where that specific page won't load from the thumbnail. I just googled it though and found this: https://gallery.autodesk.com/fusion360/projects/84023/assets/277986/embed

Re: Any ideas on a better or cheaper design for this robot spider?

etfrench — Sat, 09 Feb 2019 17:55:31 GMT

I would mount the drill so it drives the mechanism directly. Use bicycle brake cable to turn the drill on and off.

Re: Any ideas on a better or cheaper design for this robot spider?

samgaddis — Sat, 09 Feb 2019 17:58:19 GMT

Wow, I feel dumb for not thinking of that.

There are some issues with being able to reverse the drill direction, which is important to turning), but it might still be easier to engineer a solution for that than to make the 90 degree turn work.

Re: Any ideas on a better or cheaper design for this robot spider?

chrisplyler — Sun, 10 Feb 2019 02:17:14 GMT

https://www.amazon.com/NOUVCOO-Extension-Screwdriver-Attachment-NC05/dp/B076VG1539/ref=asc_df_B076VG1539/?tag=hyprod-20&linkCode=df0&hvadid=309735728871&hvpos=1o5&hvnetw=g&hvrand=12998660531122463236&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9026832&hvtargid=pla-421121137379&psc=1

Cheaper right-angle sets designed to handle the torque available from battery powered hand drills.

Re: Any ideas on a better or cheaper design for this robot spider?

samgaddis — Sun, 10 Feb 2019 22:06:07 GMT

That's probably a little too inexpensive judging by the reviews. Thanks though!

I ended up going with @etfrench 's solution of putting the drills on the bottom to direct drive the shaft. Using a bike cable to actuate the drill