Mongoose DX project

oofnik · Apr 5, 2009

Thanks MitchJi. That does sound like a good solution.

I've been working on a simpler mounting solution myself. Here's where it stands. Since I'm better with drawings than I am with words when it comes to technical things:

Apologies for the craptastic picture, but I just sketched it out real quick on paper and snapped a picture of it.
My plan is to mount angle stock to the drive, then to mount it to the frame with two U-bolts. The flat bottom of the drive will sit against the two bosses of the frame for the water bottle and hopefully prevent any rotation. The squiggly is filler - most probably rubber hose section.

I snapped the test wooden clamps into several pieces last night during testing :?. Yes, wood has been used to make machines for several centuries, bubba, but it has been replaced by metal for one major, major reason: metal is stronger! While I love your wooden design and construction, I would feel a lot more comfortable using metal.

In other news, the rear hub is currently at the LBS being built up. Hopefully it will be ready by Monday. After that, all I need is a chain, and the mounts, and I think all things mechanical will be good to go

recumpence · Apr 5, 2009

U-bolts are a sturdy way to go. My only concern is shaft rotation. You will need to add some kind of anti rotation brace to it like a brace that goes to another frame tube or some other option.

Other than that, the U-bolts whould work fine! You could even go with 4 of them for more grab.

Oh, I would recommend thin and very tough material between the U-bolt and the frame. If you use thick rubber, it will want to flex alot.

Matt

oofnik · Apr 5, 2009

4 would be good, but maybe I'll do three. I'd have to drill and tap another 1/4-20 hole in the middle of the mount, something I can't do here.
Matt, when you tapped the holes, did you tap them all the way through or from each side? I can't seem to screw a bolt all the way through.

With regards to the rubber: I can't think of something better. It needs to be flexible and not brittle. There are some pretty tough grades of rubber out there.. I'll figure something out.

edit: I'm dumb. I can just use angle stock along the entire length of the motor mount and use as many U-bolts as I want. Nevermind about the drilling and tapping

edit edit: I just thought of another solution. In addition to the angle stock and U-bolts, I could screw some flat stock in to the bosses on the frame then counterbore two screw holes into it so the drive can sit flush on top of it against the frame. This will greatly decrease the chances of slippage under heavy loading.

GGoodrum · Apr 5, 2009

oofnik said:
edit: I'm dumb. I can just use angle stock along the entire length of the motor mount...

Actually, it's not that simple. You have to cut a big notch out on one side to clear the clamp part of motor plate. The other side has to be notched as well, but not as much. I was going to use this concept on my 16" folding bike, but there's not enough room for adjustment to tighten the tension on the chain. Besides, I think it looks too cheesy. :roll:

On my other setup (see here: http://www.endless-sphere.com/forums/viewtopic.php?f=28&p=147585#p147585), I ended up drilling and tapping four more 1/4-20 holes on the bottom of the "foot", which gives you a lot more mounting options for the drive. I think Matt should consider adding these to the foot in the next batch of these.

-- Gary

oofnik · Apr 5, 2009

Aha. Thanks for the tips Gary.
Due to lack of Dremel up here in Chicago. I guess I'll just go my original route and use two small pieces of angle stock on each side. I'm pretty confident that two U-bolts plus the sandwiched flat stock will be sufficient.

I think my case is a little easier than yours, Gary; you've got a really funky shape to deal with there. :shock:

Good luck and let us know what you decide to finally do.

MitchJi · Apr 5, 2009

Hi,

oofnik said:
Aha. Thanks for the tips Gary.
Due to lack of Dremel up here in Chicago. I guess I'll just go my original route and use two small pieces of angle stock on each side. I'm pretty confident that two U-bolts plus the sandwiched flat stock will be sufficient.

I think one longer piece of angle stock on each side will look better and be a little stronger (even if you only go with 2 u-bolts). How hard can it be to file, grind, hack-saw, sawzall etc. two notches in aluminum flat stock?

I think you can figure out a way to support the flat stock on the tube on the edges on the tube which will make it quite a bit stronger.

GGoodrum · Apr 5, 2009

oofnik said:
Aha. Thanks for the tips Gary.
Due to lack of Dremel up here in Chicago. I guess I'll just go my original route and use two small pieces of angle stock on each side. I'm pretty confident that two U-bolts plus the sandwiched flat stock will be sufficient.

I think my case is a little easier than yours, Gary; you've got a really funky shape to deal with there. Good luck and let us know what you decide to finally do.

Yes, funky indeed.

I'm hoping Matt can do the new type simple clamp that Mitch described, and then clamp the assembly to the seatpost. If I can't get Matt to do it, I might try doing what Mitch proposed, and use a couple of blocks clamped toget with a spacer, and then drill out the hole. That is going to tax my abilities in this area, but I do have a drill press, so maybe I can handle it. :mrgreen:

-- Gary

oofnik · Apr 6, 2009

MitchJi said:
Hi,
How hard can it be to file, grind, hack-saw, sawzall etc. two notches in aluminum flat stock?

Pretty damn hard when you live in an apartment in the city with barely any room / money for tools and go to a school completely wrapped in red tape. :| If I were home I could knock this out in fifteen minutes, but that won't be until May.

recumpence · Apr 6, 2009

I may make the next round of drive mounts wider, like the look of Gary's and Oof's mount with the angled side flanges (but integrated into the mount foot) and mill a rounded recess into the length of the foot mount in the center to rest against the frame or seat tube. Then the customer can just use U-bolts for mounting.

Maybe the U-bolts would not look out of place with purpose built drive foot specifically for them?

Matt

12p3phPMDC · Apr 6, 2009

Wood, properly applied and chosen can be very strong.

Sugar Maple:
Tensile Strength, Ultimate: 5.31 MPa 770 psi Perpendicular to Grain
Modulus of Rupture: 0.109 GPa 15.8 ksi In Bending
0.570 g/cc 0.0206 lb/inÂ³

6061 T6 aluminum
Modulus of elasticity : 10 ksi..
2.70 g/cc 0.0975 lb/inÂ³

(material properties from Matweb)

Now, with wood, you definitely need to pay attention to the direction of the grain.
(plywood is nice, because grain orientation becomes less of an issue.
Notice the strength against the grain (perpindicular)....a measly 770 psi
Now, look at the modulus of rupture in bending, 15.8 ksi. Know, assume we could
operate at a loading 66% of the rupture point, ~10 ksi.

Now, we have a material that can take loads like 6061 T6 aluminum that is almost 5 times lighter!!!!

Wood parts definitely need to be designed with more thought due to grain issues.

So, you have to be careful when saying that metal is stronger than wood, because
it definitely depends on what you are doing and how you applying and what materials are
used.....etc..etc..etc..

From looking at the wood brackets you made, it seems that the grain is in the wrong direction.
Also, are they pine? Maple or oak can be bought at Home Depot or your favorite wood yard.

Also thin strips of wood can make a nice compression bearing that flexes less than rubber
and still provide some dampening.

Anyway, the bike is lookin good....

oofnik · Apr 6, 2009

Thank you thank you.
Yes, you're right. Wood has its merits. But it wouldn't be incorrect to say that on average, wood is weaker than metal. Given my total lack of tools, I think it would be wise to go with a solution that would use as many off-the-shelf parts as possible.

I'm booking this matweb site. Thanks

Yeah, I used pine because that's all I had laying around. And the grain is definitely in the wrong direction. Again I just made them to test, and I made them hastily at that.

GGoodrum · Apr 6, 2009

recumpence said:
Maybe the U-bolts would not look out of place with purpose built drive foot specifically for them?

I think that would be fine. It's not the U-bolts I have a problem with, it is just my cheezy-looking, unpolished "wings". :mrgreen:

When you do this, can you have some extras made? I'd like to get a couple of new "shoes" for my two existing drives.

-- Gary

recumpence · Apr 6, 2009

I will start drawing them up this weekend.

I also may make a drive mount that bolts to the rear disc brake mount so a drive coule be mounted there driving a sprocket on the disc brake flange. That would get more people going as well, though not as cool as a frame mounted drive.

Matt

oofnik · Apr 11, 2009

It's more solid than it might look.
The bottom of the foot is resting against the water bottle bosses. I can't get it to rotate no matter how much I try. Also, the position in which it's mounted doesn't create as much of a moment about the mount as if I were to mount it on the seat tube. I think it should work.

Also:

I need to take the chain back to the LBS to take out six links. You can't see but the chain is folded up at the rear of the sprocket.. it's way too long. And I should probably put a chain tensioner right where my finger is. Otherwise, it comes scarily close to the front derailleur / rear tire, and I don't want any surprises. :shock:

So mechanical is 99% done. I'm waiting on an order of wire, connectors, project boxes and zipties to go ahead and mount all the electronics which should be in early next week.

Soon... :mrgreen:

MitchJi · Apr 12, 2009

Hi,

I don't think the Hose Clamps are a good idea. In my experience the threads don't have a strong bite on the bands and it takes very little flexing to break the bands. I think you should consider something like one of the following (repeating my previous post

):
The Wraplock products:
http://www.wraplockclamps.com/

Or the Band-it products:
http://www.band-it-idex.com/products/products_bandit.html

The Flair Leg BRACK-IT design provides a secure fit that locks each leg in
place on round poles or mast arms of almost every diameter.

recumpence · Apr 12, 2009

oofnik said:
View attachment 1

It's more solid than it might look.
The bottom of the foot is resting against the water bottle bosses. I can't get it to rotate no matter how much I try. Also, the position in which it's mounted doesn't create as much of a moment about the mount as if I were to mount it on the seat tube. I think it should work.

Also:

I need to take the chain back to the LBS to take out six links. You can't see but the chain is folded up at the rear of the sprocket.. it's way too long. And I should probably put a chain tensioner right where my finger is. Otherwise, it comes scarily close to the front derailleur / rear tire, and I don't want any surprises.

So mechanical is 99% done. I'm waiting on an order of wire, connectors, project boxes and zipties to go ahead and mount all the electronics which should be in early next week.

Soon...

If those hose clamps do not work, you could always use some angled aluminum bolted to the mount foot extending a few inches forward and backward, then use multiple hose clamps on each side for many times the holding torque.

Matt

oofnik · Apr 12, 2009

Mitch -
Those bands are made of a hard stainless steel. You're right that if you bend them they become brittle, just like a paper clip - it's called work hardening. But there aren't any sharp angles in the way I've mounted it, which should help prevent that from occurring. As far as the threads breaking, well I'll go to my next solution when that happens I suppose

. I'm going to be testing a lot before I actually get on the thing and ride obviously, so we'll see.

Matt, that's a good idea as well. I could do either that or the U-bolt idea I had mentioned previously. But again, I won't go to plan B until plan A fails!

oofnik · Apr 12, 2009

[youtube]y76V3FwqpkM[/youtube]
new window

Yeahhh. 8)

Chain tensioner is awfully noisy. It's noisier than the motor. Any suggestions on fixing that? It was $10 at the bike shop, maybe I should get a more expensive one..?

Order of project boxes and electronics stuff should be in sometime early this week. I CAN'T WAIT AHH.

recumpence · Apr 12, 2009

You can put an O-ring around the idler. That O-ring will ride in the center of the chain on the idler and soften the sound.

My recumbent suffers from the same thing.

Matt

Lucky_Hoodlum · Apr 12, 2009

oofnik said:
Chain tensioner is awfully noisy. It's noisier than the motor. Any suggestions on fixing that? It was $10 at the bike shop, maybe I should get a more expensive one..?

Maybe a jockey wheel with sealed bearings be better for lower noise? I like the install of these recumpence drives i been reading the thread (very long hehe) you do excellent work recumpence, has anyone else have mounted one of these drives yet i have been looking but this is first i have seen that works so far?

oofnik · Apr 12, 2009

Lucky_Hoodlum said:
oofnik said:

Chain tensioner is awfully noisy. It's noisier than the motor. Any suggestions on fixing that? It was $10 at the bike shop, maybe I should get a more expensive one..?

Click to expand...

Maybe a jockey wheel with sealed bearings be better for lower noise? I like the install of these recumpence drives i been reading the thread (very long hehe) you do excellent work recumpence, has anyone else have mounted one of these drives yet i have been looking but this is first i have seen that works so far?

It very well may be the first. Woohoo I win!

I might scrap the idler and just figure out a way to mount half a derailleur back there. That should be a little quieter. I'll see what the bike shop has in the scrap pile tomorrow.

Lucky_Hoodlum · Apr 12, 2009

Jockey wheel=the smaller cog on bottom of a derailleur they are around 30 dollars each at bicycle shop (had to replace on my MTB) have sealed bearings
not like the cheap Walmart bikes derailleurs that have bushes instead of bearings and are much noisier. I think this would be way
to lower noise on your chain tensioner, you will still get much noise from chain i think but the wheel won't make noise.
WooHoo for being first to make drive work on bike also, i would like one of these to but can not afford right now ah well
dream for now and enjoy watching others success.

www.recumbents.com · Apr 12, 2009

Make your own (quiet) idlers:

http://www.recumbents.com/WISIL/idler/idler.htm

-Warren.

MitchJi · Apr 12, 2009

Hi,

Mitch said:
I don't think the Hose Clamps are a good idea. In my experience the threads don't have a strong bite on the bands and it takes very little flexing to break the bands. I think you should consider [band clamps]

recumpence said:
If those hose clamps do not work, you could always use some angled aluminum bolted to the mount foot extending a few inches forward and backward, then use multiple hose clamps on each side for many times the holding torque.

Matt

I think bolted Matts angled aluminum idea (or something similar) combined with U-bolts would be a better solution solution than either my previous idea (band clamps) or more hose clamps.

Instead of angled aluminum you could use rectangular stock thick enough to drill for U-bolts.

Rassy · Apr 12, 2009

Here's a picture of the mounting bracket I made for my first E-Bike experiment a few years ago. By using the pieces that come with U-bolts that have the slotted holes in them, you can tighten the U-bolt until the piece bends around the tubing, which makes a better contact patch and resists any rotation. Then use additional nuts (plus lock washers, etc) to attach the plate that the motor, etc. is attached to. Good luck however you do it.

Edit: Yes, there was a U-bolt on each end of the plate.

Mongoose DX project

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