Making Really Strong Parts

[teoman]

On another forum where I am a regular, I see guys installing fancy machined billet footpegs fo their motorbikes.

[img]http://www.advrider.co.za/images/Evo%20 ... %20800.jpg[/img]

[img]http://www.triumphrat.net/attachments/t ... cn1103.jpg[/img]


Those fancy ones cost about 200 usd a pair and a cheaper chinese set costs 100 usd. That kind of seems overpriced to me and I do not see them as a %100 necessity at the moment. Then I started pondering if I would be able to make my own. I have a 3d printer, and I could CAD those pegs without too much difficulty. The manufacturing part is what puzzles me so I decided to consult the experts on this forum.

I highly doubt that even the strongest filament will be able to widhstand me standing on them. What if i made the part out of PLA and did lost investment casting? Or is there such a resin that i can do almost the same but use the resin instead of aluminium. What would work?

On a side note, I would be happy to spend that 100-200 usd on an aluminium casting rig and then spend a bunch of time on this.


Thanks in advance.

Teoman

[Xenocrates]

Take a look at Smooth-On's Epoxy resins. They work pretty well for a variety of things. http://www.smooth-on.com/Castable-Epoxy ... index.html

A few things to note if you plan on doing casting, especially metal casting.
Molds do not last forever. For resin casting, depending on the level of detail, you may have 5 casts, or 500. Watch your molds and parts to make sure you're not pulling away chunks. For metal casting, it's likely not many castings at all, especially for Aluminum.

Things like degassing chambers and vibration tables make a big difference in part quality, and aren't cheap. A small vib table is 50$, and will hold one of those footpegs. A vacumn or degassing chamber is more expensive as well. But for both your mold material, and any resins, they are a massive change in part quality. You can build your own, but expect to be fiddling, and spend money.

Pour at a measured pace. Do not dump it in, and don't let the stream break once you start pouring. Both of those can introduce air, and cause problems.

Don't rush it. Give it the cure time it says it needs, even if it feels like it's ready earlier. a hard shell can form that breaks on unmolding.

If you want a permanent, wear resistant color, choose a colorant and resin that you can mix, and cast it at the final color. Don't paint. No amount of poly, varnish, or clear coat will keep paint on a resin when you have boots on and off, and mud as well.

[teoman]

I only need to make 2 or 4 of them.

So i am not really worried about my molds lasting.



I already have some materials for a setup:

A tiny vacuum pump:
http://www.aliexpress.com/item/NEW-DC12 ... 87933.html

A vibration motor:
http://www.aliexpress.com/item/Dual-bal ... 67180.html


I can go that route or the aluminium casting route. But i am wondering if i make it out of resin (or cast aluminium), will it be strong enough for me to jump on them. Can they take the abuse?

[Xenocrates]

Note that many of their resins are used for stamping dies, metal forming dies, and foundry tooling. I doubt that a single person will be able to exert sufficient force to break them. Their aluminum filled resin is harder than a hard hat by a good margin, and you can easily stand on those. 650 is even harder, and has higher compressive and tensile strength. If you made them the same size and shape as the aluminum pegs, I doubt you'd have any issues.

[barry99705]

I only need to make 2 or 4 of them.

So i am not really worried about my molds lasting.



I already have some materials for a setup:

A tiny vacuum pump:
http://www.aliexpress.com/item/NEW-DC12 ... 87933.html

A vibration motor:
http://www.aliexpress.com/item/Dual-bal ... 67180.html


I can go that route or the aluminium casting route. But i am wondering if i make it out of resin (or cast aluminium), will it be strong enough for me to jump on them. Can they take the abuse?

No way. Even a carbon fiber peg will snap off if you jump on it. Don't forget, it also has to stand up to a few G's of your weight as well. That's why no one makes them. All you'll find are metal, and sometimes even they snap off.

[DavidF]

Sand cast in aluminum would be the route i would take. Ive tried some of the pkastics from smooth on and they are not too bad, but i dont think i would trust my weight on any of them.

Investment casting can be as expensive, or inexpensive as you want it to be. I had $0.00 in my first vacuum chamber and it worked out just fine.

[Captain Starfish]

Time to buy yourself a CNC router and hack them out of billet.

No way would I trust even a road bike pegs to plastic or resin, let alone an offroader.

BTW: when you stack up materials, time, time to re-do it and materials to re-do it because the first choice didn't work, $100 a pair is bloody cheap.

[Eric]

If you only need 2 of them and your design isn't needlessly complex, this seems practical to make yourself from aluminum bar with basic shop tools. Drill press, band/table saw, suitable measuring/layout tools and the ability to use them.

[teoman]

If i had space, i could get a cnc, but they are probably very expensive over here.

A friend was building one, maybe i should check on him.


Programming a cnc would be fun, but i am not interested in manual labour with the drillpress and mill, I have done some of that before and the excitement is over, and as I wont be learning something new i would not want to waste time on it. (And i do not have a mill or the tools).

[Windshadow]

I do have a machine shop with Bridgeport and bandsaw etc so I am in the 6061T6 crowd of billet but I do recall seeing somewhere in the pile of CES stuff this week of someone with a combined filament deposition printer with the ability to lay in carbon fiber lengths in spaces left in the print... looked clever and I tough right away why not a print that was split into sections where carbon fiber lines or spectra or the like could be places and then epoxied as a solid item...
and then after a bottle of nice french plonk with my chicken maresla and a good brandy i started thinking about prestressed concrete and why not prestressed plastic with cords of spectra tensioned to give shear strength to plastics that are strong basically in compression....

note that i have a skin full tonight due to the storm knocking out the power for 2 hours and sitting by the fireplace drinking a good 18 year old malt scotch after diner with wine etc.. so i may be typing absolute ballocks

Damm this forum software need better smilies if it won't support modern emoji!

[barry99705]

I do have a machine shop with Bridgeport and bandsaw etc so I am in the 6061T6 crowd of billet but I do recall seeing somewhere in the pile of CES stuff this week of someone with a combined filament deposition printer with the ability to lay in carbon fiber lengths in spaces left in the print... looked clever and I tough right away why not a print that was split into sections where carbon fiber lines or spectra or the like could be places and then epoxied as a solid item...
and then after a bottle of nice french plonk with my chicken maresla and a good brandy i started thinking about prestressed concrete and why not prestressed plastic with cords of spectra tensioned to give shear strength to plastics that are strong basically in compression....

note that i have a skin full tonight due to the storm knocking out the power for 2 hours and sitting by the fireplace drinking a good 18 year old malt scotch after diner with wine etc.. so i may be typing absolute ballocks

Damm this forum software need better smilies if it won't support modern emoji!

https://markforged.com/

Spendy, then you have to buy the filament!

[teoman]

I do not think that I would like to buy a semi experimental printer just at this phase, maybe in 5 years when their tech has matured and the price has gone down.

So final verdict? Resins are a maybe, what about backyard aluminium casting?

[barry99705]

I do not think that I would like to buy a semi experimental printer just at this phase, maybe in 5 years when their tech has matured and the price has gone down.

So final verdict? Resins are a maybe, what about backyard aluminium casting?

I really don't think cast aluminum will be strong enough either. It's doable, but I wouldn't trust it.

[teoman]

If I designed my own how much would having it machined and anodized cost?

And any idea on a DIY cnc mill?

[Jimustanguitar]

If I designed my own how much would having it machined and anodized cost?

And any idea on a DIY cnc mill?

Talk to TravelPhotog about this. He's used the ShapeOko / X-Carve on aluminum more than anybody I've ever heard of.

[bot]

I would beg DavidF to cast it for you. Beg him with money.

[KAS]

I think the BullDog CNC is the one he mentioned he liked, not sure if he has it or not. http://www.bulldogcncrouters.com/

For x-mas I ended up with a Shapeoko 3. Seems to be sturdy but I'm only cutting test pieces of aluminium trying to learn it.

This is the SparkFun edition
[img]http://i482.photobucket.com/albums/rr18 ... 134220.jpg[/img]

[Captain Starfish]

I lashed out last year and got an OmioCNC X-2200L. A little more than some others but it comes with proper hywin rails and decent ballscrews - hardware that's more accurate and durable which suits me. It's not as fast as a proper big CNC mill but, given time, it eats aluminium no problems.

I'd happily run something like your pegs through it. Probably go for 7000 series ali instead of 6000 for something like a footpeg though, as the 7000 tends to be a lot stiffer and stronger.

I'd avoid casting aluminium for something like this, particularly as a first casting job. Unless you had access to x-ray NDT gear. Wayyy too easy to get a bubble or other defect in the casting which Murphy's Law will guarantee happens somewhere important.

And shopping it out? If you supply the CAD model, there's a good chance any shop you give it to will want to re-enter it in their own format anyway. They'll charge a couple hours for that. Then they have to process toolpaths, another couple hours minimum. Then the machine setup, another hour at least. Then your two pegs - about half an hour of machine time. Your raw aluminium parts just cost you $10 for the aluminium and $550 labour. Now the anodising, probably only twenty bucks or so. Add your time and stress getting it all lined up...

Those $100 Chinese ones start looking pretty cheap, neh?

[teoman]

The originals are 230 usd. Chinese ones are 100 (not copies).

They are not a necessity and I was thinking that IF it were doable i had an excuse to get in to aluminium casting. Then i got curious how i could manufacture such a strong part.

A friend just built a desktop cnc. I'll pester him when the time comes.

Thank you all for sharing your wisdom.

[626Pilot]

E3D Volcano parts have unusually thick layers, and E3D claims that they're exceptionally strong because of this. I skimmed through their blog post, but didn't see any numbers on how much abuse they can take. You could weld a few carriage bolts or other metal together for the main structural support, and then wrap them in printed ABS.

If you want to cast, there is wax filament designed specifically for mold-making. There are plenty of videos on YouTube on how to make a backyard smelting furnace out of refractory brick and cheap propane stuff. (Some people make their FULL living just from building this stuff and getting millions of people to view it on YouTube.)

[barry99705]

E3D Volcano parts have unusually thick layers, and E3D claims that they're exceptionally strong because of this. I skimmed through their blog post, but didn't see any numbers on how much abuse they can take. You could weld a few carriage bolts or other metal together for the main structural support, and then wrap them in printed ABS.

If you want to cast, there is wax filament designed specifically for mold-making. There are plenty of videos on YouTube on how to make a backyard smelting furnace out of refractory brick and cheap propane stuff. (Some people make their FULL living just from building this stuff and getting millions of people to view it on YouTube.)

Melting aluminum is pretty easy, it's the casting part that's a bitch.
[youtube]http://www.youtube.com/watch?v=hn-kxMf_KYE[/youtube]

[mhackney]

I just got to see a MarkedForge composite printer and some of my reel parts printed with fiberglass filament. Very cool indeed and actually something one could RepRap easily enough. The filament is 1.75mm Nylon and the fill filament looks to be .05mm carbon fiber, Kevlar or fiberglass. It is actually "pulled" into the part at the hot end. Everything else looks very standard. The slicer is pretty bare bones since it is pr-optimized for this one printer but it does have the infill fiber handling added.