RCCrawler Forums

phillyb · 11-09-2004, 03:36 AM

Quote:

Originally Posted by JasonInAugusta

Unlimited Engineering's fix was to get rid of the cross pin in the axle.

He did this by making the section of the axle that protrudes from the bearings hex shaped. The actual hex that fits into the wheel fits onto this hex axle shaft.

yeah i know, i have a set. this was for the weakness in drilling a hole through the axle. not the hex hole in the rim strippingout. not to mention his newer ones are 8mm, but this was mostly because 8mm bearings are easier to get (standard buggy bearing).

The assembly is the absolute strongest axle/hex assembly I've seen for RC.

yep.

Doesn't do much for plastic wheels though.

that is fixed by alu wheels he made. dont consider it much of a fix, but it does fix the problem. also with his cvds some guys were drilling holes through the rim and using 5 screws through the UE hubs. this works but not for our applications. i guess you could drill and tap the metal hubs (like inets) but not plastic.

Pro-Line's 23mm hex wheel is a cool idea, you increase the surface area, which spreads the load over a larger area.

The downside is that you're forced to use Pro-Line's wheels for the 23mm hexes. It's a sure-fire way to limit your wheel choices.

never said it was a fix, but i thought id mention it, and im probably not going to be able to use it either.

You'll also transfer the load to the axle's cross pin, which I've snapped several of with a metal, standard size, 14mm hex.

use drill blanks, they might last longer, i donno.

(tryin to help out, only been here like a week)

revobasher · 11-22-2004, 10:50 PM

Guys im in 8th grade math and my teacher said to me that the triangle is the strongest geometrical shape and i also asked her the question about what you guys were talking about and she of chorse didnt know what i was talking about so i drew her a pic and she said shed go with a triangle because it has the least resembelance of a circle ...but over all what we want is a shape that is strong enough to hold the pin in and a shape strong enough to not strip in the rim right???? and the triangle is going to get weaker on the tips of the axes right??so i thought id go with the square just because its got more beef to it and if you put the pin sideways you would have more strength right??? but oh well thats just my 2 cents
i like to here what you guys' minds are thinking though it interesting
thanks
jason b

95MoYj · 05-12-2005, 03:53 PM

What are some solutions to fixing this problem(stripped wheel hubs) the only thing i can think of is liquid nails, i also herd of wrapping the outside of the metal hex with tin foil. I am all out of ideas and dont want to buy new wheels or tires. I burnt out all 4 wheel hubs in less than 3 days

Bomb-ProofProducts · 05-12-2005, 04:31 PM

5th scale and 1/4th scale use squares.

The ue hex is a wonderful idea. Too bad Robin didnt measure the wheel correctly and get the proper size. Its a wee bit smaller than the wheel, and to add insult to injury they decided to round the edges to remove any possibility of using a plastic wheel with any form of power. Its almost as if they want you to run their wheels. Im sure that cant be the case though.

CustomCrawler · 05-12-2005, 04:44 PM

Quote:

Originally Posted by Bomb-ProofProducts

5th scale and 1/4th scale use squares.

The ue hex is a wonderful idea. Too bad Robin didnt measure the wheel correctly and get the proper size. Its a wee bit smaller than the wheel, and to add insult to injury they decided to round the edges to remove any possibility of using a plastic wheel with any form of power. Its almost as if they want you to run their wheels. Im sure that cant be the case though.

Can we get a picture?

4RnrRick · 05-12-2005, 04:44 PM

I think a square with a cross pin going from point to point would be WAY better than a hex!

BultacoJim · 05-12-2005, 04:54 PM

Have you ever seen a tapered axle like the old CJ2A Jeeps had for their wheel hubs. Those suckers will sometimes take heat, pounding, and lots of cussing to separate. If you used something like that on a crawler wheel, you would just eliminate the keyway and let the frictional forces hold the wheel to the axle. But then we would all have to switch over to metal wheels.

Vitamin_J · 05-12-2005, 05:10 PM

Quote:

Originally Posted by BultacoJim

Have you ever seen a tapered axle like the old CJ2A Jeeps had for their wheel hubs. Those suckers will sometimes take heat, pounding, and lots of cussing to separate. If you used something like that on a crawler wheel, you would just eliminate the keyway and let the frictional forces hold the wheel to the axle. But then we would all have to switch over to metal wheels.

god i hate that type!!! my old Duratrax Maximum had that and i'd have to tighten it up every 2 minutes!

mike · 05-12-2005, 05:28 PM

i think the way to not strip out your hexxes and whatever is to make shure they are properly instaled and are titened corectly. ive never striped any thing useing this method.

Davkin · 05-12-2005, 06:20 PM

Just my two cents the subject. I am a mechanical designer and work in an engineering office. First, the "Triangle is the strongest geometric shape" argument. When this is said it's referring to structual members, this is not what we are doing with transmitting power to our wheels in R/C trucks. This is why you see trusses on bridges with thier members arranged in ways that form tirangular shapes, this is an entirely different situation than what we are talking about. However, I do think a triangle would be stronger, but for a different reason. If you look at the angles of the force being applied at the edges of whatever shape you are using the angle that is the greatest from the edge of the shape will give you the shape that will least likely strip out. Think of a circle running around the hex at it's points, that's the force that is trying to strip the hex. For simplicity sake, imagine one of the hex corners sitting straight up, then take a line straight off that corner parallel with the ground. Now look at the angle this line makes to the side of the hex. Now imagine a triangle or even a square in the same situation. That angle is much greater, which means it will take more force to overcome the shape and cause it to strip. That said however, I don't think the hex drive is a bad design, it's just often executed poorly. If there is any slop in the hex to wheel fit then you're almost guaranteed to strip it. The pin only design is very poor, circles strip very easy. You have very, very little contact area with a pin. I beleive the best design for power transfer would be a blade, assuming it is thick enough and long enough. Even with slop in the slot it will not strip.

David

Bsmooth · 05-12-2005, 07:35 PM

what about a star shaped drive adapter? simple to manufacture, and if done correctly it should be stronger than a hex. Also, have we considered that it is not the shape, but the material of the hex that is the downfall?

mike · 05-12-2005, 07:40 PM

i think that a triangle or square would were quiker and have alot of play in it. also, why would the axle shafts on a 1:1 be round (with splines) and not triangle if round was weeker. :?

Bomb-ProofProducts · 05-13-2005, 07:08 AM

Here is a link to a drawing of a 5th scale front end. Notice the Hex's.
Square hex

FrankyRizzo · 05-13-2005, 10:44 AM

I know in some industrial applications this style of shape holds up well. I know it would obviously take some work to get a wheel made to acccept it but I think that this type of hub would be very strong for power transfer and durability.

http://www.freepichosting.com/Thumbs...22/154/156.jpg

Davkin · 05-15-2005, 12:24 PM

Quote:

what about a star shaped drive adapter?

A star shaped adapter would be like using 5 smaller triangles, so ya, it would be stronger than the hex.

Quote:

Also, have we considered that it is not the shape, but the material of the hex that is the downfall?

I beleive there was some discussion of that earlier in the thread. The problem is, if you make the hex out of aluminum or some other material stronger and harder than plastic you will strip the wheel, in fact I think that's what most people are seeing, stripped wheels. If the wheel was made out of aluminum as well then it would be tough to strip that, but then we are talking $$$$$$.

Quote:

i think that a triangle or square would were quiker and have alot of play in it

The shape has nothing to do with the amount of play, it's the manufacturing tolerances. Some shapes are better able to tolerate a small amount of play than other though. Triangles and squares would tolerate more play than hexes. Splines and stars would tolerate even more play as long as the splines and valleys of the star are deep enough.

Quote:

i think that a triangle or square would were quiker and have alot of play in it

That is a spline, a very coarse spline but still a spline. Yes, that would be much stronger than a hex, but more costly to produce, at least in the short run. However, since hexes are the standard the wheel manufacturers would have to supply the adapters with the wheels to gain acceptance. Then I think you'll find the pin to hex connection is the weak point. I think the pin design is okay, as long as they make it deeper into the hex which would require a whole different shaft design so that isn't going happen.

David

Jeeper · 05-15-2005, 02:05 PM

the ideal idea would be to create a hub just like a real car and have like three nuts holding the wheel to the axle. it would be strong and look realistic.

11-22-2004, 10:50 PM	#22
revobasher Rock Stacker Join Date: Nov 2004 Location: dallas tx Posts: 55	Re: triangles/squares instead of hexes Guys im in 8th grade math and my teacher said to me that the triangle is the strongest geometrical shape and i also asked her the question about what you guys were talking about and she of chorse didnt know what i was talking about so i drew her a pic and she said shed go with a triangle because it has the least resembelance of a circle ...but over all what we want is a shape that is strong enough to hold the pin in and a shape strong enough to not strip in the rim right???? and the triangle is going to get weaker on the tips of the axes right??so i thought id go with the square just because its got more beef to it and if you put the pin sideways you would have more strength right??? but oh well thats just my 2 cents i like to here what you guys' minds are thinking though it interesting thanks jason b

05-12-2005, 03:53 PM	#23
95MoYj Pebble Pounder Join Date: May 2005 Location: Hacienda Heights Posts: 143	What are some solutions to fixing this problem(stripped wheel hubs) the only thing i can think of is liquid nails, i also herd of wrapping the outside of the metal hex with tin foil. I am all out of ideas and dont want to buy new wheels or tires. I burnt out all 4 wheel hubs in less than 3 days

05-12-2005, 04:31 PM	#24
Bomb-ProofProducts Newbie Join Date: May 2005 Location: Augusta Posts: 12	5th scale and 1/4th scale use squares. The ue hex is a wonderful idea. Too bad Robin didnt measure the wheel correctly and get the proper size. Its a wee bit smaller than the wheel, and to add insult to injury they decided to round the edges to remove any possibility of using a plastic wheel with any form of power. Its almost as if they want you to run their wheels. Im sure that cant be the case though.

05-12-2005, 04:44 PM	#26
4RnrRick Rock Crawler Join Date: Dec 2004 Location: www.ORCRC.com Posts: 693	I think a square with a cross pin going from point to point would be WAY better than a hex!

05-12-2005, 04:54 PM	#27
BultacoJim Pebble Pounder Join Date: Oct 2004 Location: Colorado Posts: 165	Have you ever seen a tapered axle like the old CJ2A Jeeps had for their wheel hubs. Those suckers will sometimes take heat, pounding, and lots of cussing to separate. If you used something like that on a crawler wheel, you would just eliminate the keyway and let the frictional forces hold the wheel to the axle. But then we would all have to switch over to metal wheels.

05-12-2005, 05:28 PM	#29
mike RCC Addict Join Date: Nov 2004 Location: Redding, CA Posts: 1,288	i think the way to not strip out your hexxes and whatever is to make shure they are properly instaled and are titened corectly. ive never striped any thing useing this method.

05-12-2005, 06:20 PM	#30
Davkin Pebble Pounder Join Date: Mar 2005 Location: Utah Posts: 156	Just my two cents the subject. I am a mechanical designer and work in an engineering office. First, the "Triangle is the strongest geometric shape" argument. When this is said it's referring to structual members, this is not what we are doing with transmitting power to our wheels in R/C trucks. This is why you see trusses on bridges with thier members arranged in ways that form tirangular shapes, this is an entirely different situation than what we are talking about. However, I do think a triangle would be stronger, but for a different reason. If you look at the angles of the force being applied at the edges of whatever shape you are using the angle that is the greatest from the edge of the shape will give you the shape that will least likely strip out. Think of a circle running around the hex at it's points, that's the force that is trying to strip the hex. For simplicity sake, imagine one of the hex corners sitting straight up, then take a line straight off that corner parallel with the ground. Now look at the angle this line makes to the side of the hex. Now imagine a triangle or even a square in the same situation. That angle is much greater, which means it will take more force to overcome the shape and cause it to strip. That said however, I don't think the hex drive is a bad design, it's just often executed poorly. If there is any slop in the hex to wheel fit then you're almost guaranteed to strip it. The pin only design is very poor, circles strip very easy. You have very, very little contact area with a pin. I beleive the best design for power transfer would be a blade, assuming it is thick enough and long enough. Even with slop in the slot it will not strip. David

05-12-2005, 07:35 PM	#31
Bsmooth Quarry Creeper Join Date: Mar 2004 Location: 18" from computer screen Posts: 213	what about a star shaped drive adapter? simple to manufacture, and if done correctly it should be stronger than a hex. Also, have we considered that it is not the shape, but the material of the hex that is the downfall?

05-12-2005, 07:40 PM	#32
mike RCC Addict Join Date: Nov 2004 Location: Redding, CA Posts: 1,288	i think that a triangle or square would were quiker and have alot of play in it. also, why would the axle shafts on a 1:1 be round (with splines) and not triangle if round was weeker. :?

05-13-2005, 07:08 AM	#33
Bomb-ProofProducts Newbie Join Date: May 2005 Location: Augusta Posts: 12	Here is a link to a drawing of a 5th scale front end. Notice the Hex's. Square hex

05-13-2005, 10:44 AM	#34
FrankyRizzo I wanna be Dave Join Date: Apr 2005 Location: Vegas Posts: 7,172	I know in some industrial applications this style of shape holds up well. I know it would obviously take some work to get a wheel made to acccept it but I think that this type of hub would be very strong for power transfer and durability. http://www.freepichosting.com/Thumbs...22/154/156.jpg

Sponsored Links

05-15-2005, 02:05 PM	#36
Jeeper Rock Stacker Join Date: Aug 2004 Location: wasatch front Posts: 77	the ideal idea would be to create a hub just like a real car and have like three nuts holding the wheel to the axle. it would be strong and look realistic.

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