Home made parts...

[Scottly]

Any of you fellas into making your own parts and bits? I'm a hobby machinist and I just made a set of footpeg lowering brackets for my '09 R1200RT. I looked at the picture from Suburban Machine and made something similar. (Disclaimer: I do NOT sell these...for personal use only) I was going to make a brake pedal extender next.....maybe a nice aluminum holder for a GPS.

Any ideas?

[cfell]

yeah..... some ideas..

... Rifle/shotgun rack/scabbard.. something that would allow a leather or synthetic liner.. preferrably a vertical stow
... Pistol scabbard.
--- aluminum seat pans...
... auxillary light mounting bars/brackets
... 14mm gearbox wrenches
... lift bracket to fit the LT to a Sears Bike lift..

[haughty]

[QUOTE=cfell]yeah..... some ideas..

... Rifle/shotgun rack/scabbard.. something that would allow a leather or synthetic liner.. preferrably a vertical stow
... Pistol scabbard.
--- ^^^^^^^^^^^^^^^^^^^^^^^^
DEFINITELY from TEXAS!

I want pics!

[meese]

... Rifle/shotgun rack/scabbard.. something that would allow a leather or synthetic liner.. preferrably a vertical stow
... Pistol scabbard.Look at ATV accessories. :)

[Tom1200]

Cup holder with a plug in heater for the morning coffee
Highway boards that fit under the tip over wing that work with the mick o pegs

[jimfastcar]

I have a concern, and first will note that I am not a machinist or otherwise qualified to critique your thinking, but not long after I installed the Suburban Machinery parts I was doing a long ride and stood on the pegs to rest my knees. It occured to me that I was hoping the metal quality was such that it would withstand that much weight in such a concentrated area, and I suspect the hefty price is influenced by the quality of the metal used and the fact that it is machined from a block of such metal.
If it were to fail/snap while standing on it at 120 Km/h, I could probably kiss my ass goodbye as the sudden drop in my body to one side would be hard to recover from..

Just a thought - again, not pretending to be an engineer

[cfell]

Like dis...

[katnapinn]

I have a concern, and first will note that I am not a machinist or otherwise qualified to critique your thinking, but not long after I installed the Suburban Machinery parts I was doing a long ride and stood on the pegs to rest my knees. It occured to me that I was hoping the metal quality was such that it would withstand that much weight in such a concentrated area, and I suspect the hefty price is influenced by the quality of the metal used and the fact that it is machined from a block of such metal.
If it were to fail/snap while standing on it at 120 Km/h, I could probably kiss my ass goodbye as the sudden drop in my body to one side would be hard to recover from..

Just a thought - again, not pretending to be an engineer
Well I guess anything is possible but highly unlikely the a SOLID piece of aluminum would break just by standing on them. I know I've stood on mine lots of times to stretch and never thought of it breaking. Now I have thought of my foot sliping off at 80 mph. :wow:

[Scottly]

I have a concern, and first will note that I am not a machinist or otherwise qualified to critique your thinking, but not long after I installed the Suburban Machinery parts I was doing a long ride and stood on the pegs to rest my knees. It occured to me that I was hoping the metal quality was such that it would withstand that much weight in such a concentrated area, and I suspect the hefty price is influenced by the quality of the metal used and the fact that it is machined from a block of such metal.
If it were to fail/snap while standing on it at 120 Km/h, I could probably kiss my ass goodbye as the sudden drop in my body to one side would be hard to recover from..

Just a thought - again, not pretending to be an engineer

Appreciate the thoughts...and good thoughts at that.

The aluminum I used for my blocks is 6061-T6....in english, that means in T6 temper it has a tensile strength of about 40,000psi with only 10% elongation(stretch before break). It's common use is for aircraft structures and light weight bicycle frames.
But, let's say it's a softer, more basic grade of aluminum alloy such as 6063 with only 18,000psi tensile strength was used for the blocks. It's still going to be much stronger, just due to the thickness and volume, than the tiny, thin, little tabs that extrude from the footpeg mounting plate, which appears to be made from some cheap pot metal.
Also, the chunk of aluminum that makes up the block is also much thicker than the chunk that comprises the footpeg at the point it conncects to the pivot pin.

Believe me when I say that long before Suburban Machine blocks...or mine....fail, something else will.

[jimfastcar]

Good, I was actually worried, but you obviously know what you are doing. That all sounds like Turkish to me

[tbarstow]

Good, I was actually worried, but you obviously know what you are doing. That all sounds like Turkish to me


In layman's terms:

If a material has a 40,000 psi tensile strength, a round bar that has 1 square inch of cross sectional area will fail (break) at a load of 40,000 pounds before it breaks.

So (in theory only and all other factors ignored), if you weigh 200 pounds, to make a 40,000 psi load on a part, the cross section of the part would have to be .005 square inches. At .25 square inches, it you're 200 pounds only makes a load of 800 psi, not even enough to get the part to start to bend or stretch.

When you start adding up the cross sectional area on a footpeg, its a lot more area than you think and takes a LOT more load to get it to fail than you think.

That's why they can make stuff on the LT out of aluminum and zinc castings, as the part cross sections are big enough that the low strength materials will perform just fine.

[PadG]

In layman's terms:

If a material has a 40,000 psi tensile strength, a round bar that has 1 square inch of cross sectional area will fail (break) at a load of 40,000 pounds before it breaks.

So (in theory only and all other factors ignored), if you weigh 200 pounds, to make a 40,000 psi load on a part, the cross section of the part would have to be .005 square inches. At .25 square inches, it you're 200 pounds only makes a load of 800 psi, not even enough to get the part to start to bend or stretch.

When you start adding up the cross sectional area on a footpeg, its a lot more area than you think and takes a LOT more load to get it to fail than you think.

That's why they can make stuff on the LT out of aluminum and zinc castings, as the part cross sections are big enough that the low strength materials will perform just fine.

Good thinking, but not quite accurate!! :)

Tensile strength means the stress that the material can take in tension - that is, if you pull on the piece of metal from end-to-end. The foot-peg is not in pure tension, but is subjected to bending stress (tension on top and compression on bottom, the way that the foot peg is normally "loaded"), and worse yet it is a "cantilever". On top of that, to evaluate the strength capabilities, you need to look at its weakest point, which will be the thinnest material section closest to where it is attached to the bike.

Bottom line is that your calculation is way off. Yeah, I am nit-picking. Chances are the foot pegs are plenty strong enough.

[jimfastcar]

I guess the degree from MIT is part of the price for the Suburban parts !! ;)

[meese]

I guess the degree from MIT is part of the price for the Suburban parts !! ;)Nah, that's just basic material design stuff that you can get at any tech college. The MIT guys are working on flux capacitors, force field shields, and tractor beams (like this one (http://bmw.co.uk/bmwuk/about/news/0,,1156___co-181251681,00.html)). :D

[tbarstow]

Good thinking, but not quite accurate!! :)

Bottom line is that your calculation is way off. Yeah, I am nit-picking. Chances are the foot pegs are plenty strong enough.


If you want to be accurate, note that it starts with: In layman's terms.

[Scottly]

I machined them and my 300lb fat ass jumped up and down on them and they didn't break.

Does that settle it? :-)

Besides, I think the pins used are the weakest link, based on the thickness of the blocks after machining.
If you'd prefer, I can list the Rockwell hardness of the pins to be sure. :-0

[PadG]

If you want to be accurate, note that it starts with: In layman's terms.
Sorry, not accurate and layman's term isn't even close in meaning nor intent! :)

In layman's term, you were describing pulling the foot peg from end to end, while I am saying that is not how a foot peg is loaded! The darn thing is being bent by the rider putting his foot on a peg, and not by the peg being pulled apart. If it's going to break, it will be because of the weight bending it!

FYI, materials like aluminum and steel typically has a much higher tensile strength than compression strength (the reverse is true for concrete and cast iron, for examples). Note also that in bending, the material is subjected to both tension and compression stresses, as stated in previous message. So, maximum compressive tensile strength for the material is more important. Also, the foot peg being a cantilever, the maximum stress is at the point of support, or attachment, in this case. Needless to say, the thinnest section near the suppport is where the break will occur, in the event that it is over-stressed.

[PadG]

I machined them and my 300lb fat ass jumped up and down on them and they didn't break.

Does that settle it? :-)

Besides, I think the pins used are the weakest link, based on the thickness of the blocks after machining.
If you'd prefer, I can list the Rockwell hardness of the pins to be sure. :-0
Hey, no argument there!!! :) 6061 is a good material, and quite easy to machine to boot.

[tbarstow]

Sorry, not accurate and layman's term isn't even close in meaning nor intent! :)

In layman's term, you were describing pulling the foot peg from end to end, while I am saying that is not how a foot peg is loaded! The darn thing is being bent by the rider putting his foot on a peg, and not by the peg being pulled apart. If it's going to break, it will be because of the weight bending it!

FYI, materials like aluminum and steel typically has a much higher tensile strength than compression strength (the reverse is true for concrete and cast iron, for examples). Note also that in bending, the material is subjected to both tension and compression stresses, as stated in previous message. So, maximum compressive tensile strength for the material is more important. Also, the foot peg being a cantilever, the maximum stress is at the point of support, or attachment, in this case. Needless to say, the thinnest section near the suppport is where the break will occur, in the event that it is over-stressed.

I think you're missing the point. I was simply trying to give someone who didn't understand an answer a very simple example that might provide some clarity. If I wanted to debate the bending moment forces and really make my post unreadable, I would have.

If you bend it, the tension side still wins, as the tensile strengths are much greater than the compressive strengths.

In the end, just make sure you leave a radius on your internal corners so you don't make a part with a large stress riser.

Now, back to riding!

[PadG]

I think you're missing the point. I was simply trying to give someone who didn't understand an answer a very simple example that might provide some clarity. If I wanted to debate the bending moment forces and really make my post unreadable, I would have.

If you bend it, the tension side still wins, as the tensile strengths are much greater than the compressive strengths.

In the end, just make sure you leave a radius on your internal corners so you don't make a part with a large stress riser.

Now, back to riding!
Just friendly comments, OK!!! No knocking intended.... :)

You should know that the material's tensile and compressive strength are what is used to design so that the part subjected to either of these stress will not fail! So.....if the allowable compressive stress is lower than tensile, then the compressive stress becomes more important. For a simple uniform x-section beam, the tensional stress on top is equal to the value of the compressive stress on the bottom.

The other thing that you should realize also, if you were a mechanical engineer or designer, is that the stress (whether tension or compression) at any point on the "beam" (in this case, the foot rest) is not simply load/area as you had tried to state. It has a lot to do with how that beam is supported and where the loading is with respect to the support(s). It is not as simple as you had made it out to be.

it is all academic though, but I just hate seeing misinformation or misunderstandings, that's all! ;)

[bowlesj]

Geeez. He just took some hunks of metal and made some nice pegs. It's not like he's landing on the moon with this set up. :cool:

All my life I've had engineers design it to death. Then I take all their "suggestions" and do what works. They redraw and we're good to go. :)

[Scottly]

In the end, just make sure you leave a radius on your internal corners so you don't make a part with a large stress riser.

Now, back to riding!

I'm one of those nutty EAA guys, so we pay close attention to stress risers. :-)

Seriuously though, I never intended this thread to be about engineering or anything complicated. A long time ago, I realized that when my doctor started talking gibberish that i didn't understand, I viewed him the same way others viewed me when I started talking about bend allowance, metal grain (yes, it has grain like wood), weld penetration, dissimilar metals and corrosive properties of such, etc.....you get the point. I just wanted a simple discussion of some ideas on what the bike needed improvement on and what I could possibly concoct to do that. I have no intention on selling any parts to anyone....I'll leave that to the professionals at Suburban Machine. I'm just a hobbiest.

[SilverBuffalo]

I have a concern,
If it were to fail/snap while standing on it at 120 Km/h,
I could probably kiss my ass goodbye I think all of your "high tech" explanations are missing the point.

Unless you're about to hit a pot hole or some debris
I can't think of any "sane" reason why anyone would "stand up on the pegs" at 70+mph.

If your ass gets sore/tired pull over and smell the flowers,
life is much too short already.

[BMWGS]

Any of you fellas into making your own parts and bits?

Just about all of them, or at least modifying them for a custom installation. Its a win-win situation in that you get parts and bits that look like they "belong", they cost a lot less and you get a lot of personal satisfaction.

I have a slew of stuff I've made on the Technical Stuff page on my SmugMug site. Maybe it'll give you some ideas.

I'm a hobby machinist...

Same here. Bought a lathe/mill combo just over a year ago. Next is a huge compressor and media blasting booth...maybe even a TIG.

[BMWGS]

I can't think of any "sane" reason why anyone would "stand up on the pegs" at 70+mph.

In fact, depending on where you ride, it'll get you a ticket.

[Scottly]

Same here. Bought a lathe/mill combo just over a year ago. Next is a huge compressor and media blasting booth...maybe even a TIG.

Got a separate mill, lathe, miller Synchrowave 200 TIG, 7hp verticle tank compressor....no blast booth, though.

I think that may be next....after the DRO for the lathe.

[XMagnaRider]

...I can't think of any "sane" reason why anyone would "stand up on the pegs" at 70+mph....
On a long ride, the knee protectors in my outer riding pants can get shifted out of place.

To get the knee protectors back into place, I put my weight on the pegs, lift my tail off the seat, and shake my knees gently. It is a quick adjustment, not a long, full-height stand, but my body weight is held up by the pegs. I do it on an open, straight highway, not in the twisties. It takes a second at most, and doesn't feel remotely dangerous to me.

I never thought about it, but I trust the pegs to hold me up. If a peg were to break suddenly at highway speeds, it would be surprising and scary, but I believe that I would maintain control of the motorcycle. I can think of many high-risk failures that are much more likely to happen on an open highway (e.g., catastrophic tire failure, final drive instant lock-up, etc.). A sudden peg failure is not one of them. I am not a metallurgy expert, but I bet that there would be plenty of warning signs where the peg feels "soft", or bent, or it flexes unnaturally, long before it snaps completely off.