pic: Harbor Freight 8 inch tire on 3d printed hub
 

Re: pic: Harbor Freight 8 inch tire on 3d printed hub
 

Have you tested the strength of the wheels yet? Our 3D printed parts usually hold up pretty well if there isn't much shearing force. If someone hits you from the side, you might get quite a lot of that.

Re: pic: Harbor Freight 8 inch tire on 3d printed hub
 

Did you design the hub or use a previously created file?

Also, could you post the CAD file?

Re: pic: Harbor Freight 8 inch tire on 3d printed hub
 

So far it feels pretty strong, we'll test a bit more when the rest of our belts come in. My hope is that most of the load will be taken in the tire and soften the blow to the wheel itself.

I wasn't a huge fan of the look of the hubs from AndyMark so we designed our own but used some of their proven geometry to interface with pulleys and sprockets. There were probably more efficient designs, but these look good.

I'll post CAD soon, but I would want to make some changes first. The wheel is a tight squeeze in the tire and requires a bit of coaxing to get it together. All in all it turned out okay though.

Re: pic: Harbor Freight 8 inch tire on 3d printed hub
 

Are the tubes/tires from those actually 8", or are they 200x50mm?

Re: pic: Harbor Freight 8 inch tire on 3d printed hub
 

The are actually a little bigger than 8" when aired up. I think they were around 8.75 all said and done. The tire size is determined by the hub and measures 2.50-4 on these.

Re: pic: Harbor Freight 8 inch tire on 3d printed hub
 

Hey neighbor... How much for you to print us up some hubs? We're striking out getting 8" wheels - everything is sold out. We looked at the HFT wheels but they were so heavy with the steel hubs.

Re: pic: Harbor Freight 8 inch tire on 3d printed hub
 

Nice!

It's important to note that the Harbor Freight tires will not work with the stock Andy Mark Hubs anyway, and it can be a bit dangerous to try.

Re: pic: Harbor Freight 8 inch tire on 3d printed hub
 

The cost isn't the big part... it's the time. 33 hours for each side of the robot. 66 hours is a loooooooooot of printing.

If you really want to we probably could do it, it's at least double the price of Andymark. Wouldnt you know it, once i hit print on the second set, AM hubs came back in stock. I'd have to do math to figure the numbers out for you and I'm nowhere near ready to be in a BOM mood yet...

I'll put a kid on it tomorrow and run the numbers for you though.

Re: pic: Harbor Freight 8 inch tire on 3d printed hub
 

Andy, will the AM hubs fit the HFT wheels close enough to use?? Did you try them?

Re: pic: Harbor Freight 8 inch tire on 3d printed hub
 

They fit very very loose. The hubs spin inside the tire. You might be able to add material to the hubs, but I would have little faith in running the AM hubs with a non 200x50 tire. I think Airway Oxygen carries wheelchair tires though.

Re: pic: Harbor Freight 8 inch tire on 3d printed hub
 

When inflated the HF tire bead will push past the wheel.

We sliced the HF hubs up to make adapter rings that fit over the AM hubs. They fit surprisingly well.

Re: pic: Harbor Freight 8 inch tire on 3d printed hub
 

Any update on the CAD of this wheel, and how they've been working for you?

We have some solid printing abilities, and if this saves weight we're definitely interested in trying a few out.

Also: How much filament is each wheel?

Re: pic: Harbor Freight 8 inch tire on 3d printed hub
 

http://www.thingiverse.com/thing:1275569

Here you can download the .stl file of the hub!!!

Re: pic: Harbor Freight 8 inch tire on 3d printed hub
 

If anyone is interested, I updated my file and will post a Thingiverse link tomorrow. They seem to hold up okay, but we haven't aggressively tested yet. That won't be done until next week, unfortunately.

Re: pic: Harbor Freight 8 inch tire on 3d printed hub
 

What infill percentage did you print these at? Also, infill pattern?

Re: pic: Harbor Freight 8 inch tire on 3d printed hub
 

I don't have control over my infill or patterns with a Stratasys machine, so we went with near solid fill. However, we did destroy our first hub this afternoon. I would love to say that I will still update and post CAD for these, but I don't want a failure coming back to haunt us with bad juju. If you do decide to print hub, make sure that the flange is very stout as that is what de-laminated on us.

It was a fun experiment, but unfortunately it wasn't meant to be.

Re: pic: Harbor Freight 8 inch tire on 3d printed hub
 

Interesting. Which part broke exactly?

EDIT: Did another read through. So if the hub delaminated, are you printing in ABS?

I think we'll print one of these up in PLA at ~20% infill, and see what happens. I'll post results here after we're done.

Re: pic: Harbor Freight 8 inch tire on 3d printed hub
 

The bead flange specifically is what broke. We were counting on theses more than we should have, so now it's time to scramble. We can still drive the thing around, but it reminds me of my first truck I had when I was 16. The broken wheel is held in place only by air pressure on one side now, so it has a wicked wobble and can't move very fast without eating itself.

Re: pic: Harbor Freight 8 inch tire on 3d printed hub
 

We were in a very similar situation, and sorta still are.

I'm currently printing a pair of these hubs at 100% infill on PLA, to see how they hold up. 20 hours to go.

Our current driver is running on AndyMark hubs (was lucky enough to get them in before they went out of stock) and Amazon 200x50mm wheels. We found that, like many have said, the hubs don't line up with the bead. We were able to adapt this by using the metal hub that came with the wheel initially, hacking it up a bit, and epoxy'ing them to the hub.

So far, holding well. Have been aggressively testing it over the rock wall, moat, rough terrain with no noticeable issues.

Re: pic: Harbor Freight 8 inch tire on 3d printed hub
 

MrBasse, do you have access to a lathe? It looks like you could turn some hubs with similar dimensions that should be stronger. Just a thought. We're in a similar situation but went with turned hubs to work with some Northern Tools tires and rims. They should work with any rim that has a 2.75" x 4 bolt pattern. If you're interested I can email you our CAD files if that would help.






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