Topic: Aluminum fabrication for Dummies

[70CB750]

If you want to drill a 38mm hole in aluminum what would you use?

A hole saw...

Depends how precise the hole needs to be.  To get it within reasonable tolerance you would need a lathe or mill with boring bar.

But for my carb stay I made few years ago hole saw was good enough.

[DavePhipps]

Thanks for the info guys.
I  may have to take some classes outside of my degree path so I can access the CNC machines.

[754]

I would use an annular cutter like Rotobroach, if i had one.. Many ways to do it..

How thick is material? Going straight in? What are you going to turn the cutting tool with ?

[754]

He sent me a note, and said it was for a triple tree.
 In that case, the only  thing, that will work  or is easy is the annular cutter. Beyond that you would need big drills, and bore to finish, or. Doe the holes with a CNC..by cutting around the hole. If you dont have access to a mill or CNC mill , you can accurately postion the holes using toolmaker buttons and micrometers, but tou still need some big mics, and apretty big lathe, or a mill with boring equipment...
  Good luck..

[FunJimmy]

Ya, precision parts require precision maching.
The methods discussed in this thread are not suitable for producing highly precise parts.

[HondaMan]

Ya, precision parts require precision maching.
The methods discussed in this thread are not suitable for producing highly precise parts.

Right you are! These are for producing CUSTOM parts!

[Retro Rocket]

Ya, precision parts require precision maching.
The methods discussed in this thread are not suitable for producing highly precise parts.

Now we know that, i agree...

[70CB750]

He sent me a note, and said it was for a triple tree.

Na endlich, alles klar. 

I was wondering for a while, what is the tolerance on top bracket from triple tree?

[FunJimmy]

I was wondering for a while, what is the tolerance on top bracket from triple tree?

Triple trees have to be perfect! If the fork tubes aren't perfectly parallel the bushings will wear faster and the forks will not operate optimally. Misalignment can lead to fork bind and cause dangerous handling conditions.

If you're not a machinist and do not have access to precise milling machines, purchase triple trees from a quality vendor.

[70CB750]

I was wondering for a while, what is the tolerance on top bracket from triple tree?

Triple trees have to be perfect! If the fork tubes aren't perfectly parallel the bushings will wear faster and the forks will not operate optimally. Misalignment can lead to fork bind and cause dangerous handling conditions.

If you're not a machinist and do not have access to precise milling machines, purchase triple trees from a quality vendor.

I know 

My question was for the tolerance such as H8/h9 or H11/h9.

[RAFster122s]

Jimmy,

What thickness of material did you choose to use for the Cone Muffler support bracket and the rear sets. The muffler support bracket appears to be around 1/4" (maybe 3/16 but I doubt it given the distance you were supporting. The rear sets plate I would guess is 3/8" or possibly thicker.

How do you make the design decision on the thickness of the plates you are making up?
Naturally, for the rear sets it is going to need to handle your weight x2 or x3 for durability sake (x3 or x2 because if you happen to be up on the pegs and go over a heavy bump or pothole you could see loads that exceed your weight by those factors...shocks only do so much...) Normally, I would try to avoid a pothole or heavy bump if possible, but you have to design to handle it for those just in case times when things like that "sneak up" on you in life.

Are you using a 3031?(brain fade on the grade of 30xx) Aluminum or a 6061 or other grade? (6061 would be hard to machine, whereas 3031 can be easily machined)

For a speedo and tach bracket, to eliminate vibrations from the material and yet still make it easily bendable so you aren't fabbing out of a billet blank you would use what thickness material?  For an example...  (I'm leaning towards something greater than 1/8" and probably 3/16")

Thanks!


David

[754]

Just jumping in here.
6061 T6 is the most often used. In a few cases7075 T6. The only one that is hard to machine.
If you are making brake parts that will see extreme heat you might consider 2024 Alloy.
 
 3/8 is plenty for rearsets, 5/16 is probably enough. Depends on how much things are hanging out unsupported.
 It's very tough, and you can easily test an unfinished piece by bolting to something solid, and bouncing on it with your weight, watching for deflection.
 Watch the wings on a 747. They flex about three feet up and down,  but they are probably 7075.

[FunJimmy]

Good points Frank.

Material selection is often based on what I've got in the scrap metal bucket at the time but 6061 T6 is the likely choice. 7075 T6 is harder to machine and not formable so parts requiring bends need to be 6061 T6 or 2024. For simplicity, I'll often use an extrusion (angle, box etc) if I can section from that.

I'll post a picture of the back rest I recently made for my Triumph 1050 Tiger. Interestingly the first generation was mostly long spar 1/8" sheet aluminum and it was strong yet flexible. For peace of mind and in the event my wife needs to press hard against to reduce bum pressure, I chose to make the final product from 3/16 plate 6061 T6 aluminum. It is extreamly rigid.

[754]

7075 can be formed but NOT to as tight as 6061 usually is.
 Jimmy has a good grasp on it and is very creative with the limited tools he has. Kudos to him.
 Plus what I like is he likes to share it on here.

[scottly]

6061 T6 will crack when bent only a small amount, unless annealed first. I did test bends with thin 6061 before making my battery tray. Before annealing, the test strips would break off when bent to about 45 degrees. After annealing, I was able to achieve 90 degree bends. Bending was done in a 6" bench vise, with a block of wood and a hammer.
 

[FunJimmy]

6061 T6 will crack when bent only a small amount, unless annealed first.

Ah ha, i've got my designations wrong. I should have said 6061.

Grade Summary: This is the most versatile of the heat treatable aluminum alloys. This alloy offers a wide range of mechanical properties and corrosion resistance. It is easily fabricated and has good formability. It is weld-able using all wethods including furnace brazing.

http://metalsupermarkets.com/metals/consumer-guide/aluminum/

[754]

Scottly if you annealed it, now it's at about 1/2 strength.
6061 T6 gets bent millions of times a day, just a matter of  using the right radius die tip.
 Your  1/8 pieces clamped against a 3/8 bar should bend beautifully in hard condition.
Probably. A bit tighter radius than your middle parts.
 Bend rad will be shown in handbooks as. 2T Rad or 3T Rad.    The T being thickness of material
Bend rad on 7075 would be more like 4T or 5T.

 The other thought I had was doing it with a hammer may invite fracture. You can easily whip up a small set of dies to use in a bench vise or Arbor press.

[scottly]

That's actually about .030" thick, Frank, and the strength when bent at that tight radius was about zero before annealing.  Even at 1/2 strength, I figured it would support the 12 oz battery with no problems, and so far it has.  

[FunJimmy]

What thickness of material did you choose to use for the Cone Muffler support bracket and the rear sets. The muffler support bracket appears to be around 1/4" (maybe 3/16 but I doubt it given the distance you were supporting. The rear sets plate I would guess is 3/8" or possibly thicker.

David,

You guessed right. The Cone muffler support is 1/4" but oddly the rear-sets are 0.400" (just a tad thicker than 3/8") possibly 10mm.

Here's the backseat I made for my Triumph Tiger using 3/16" aluminum and it's suprisingly strong.

[754]

Nice job and handy to lift the whole bike.  ... Not gonna have any give in crash. Looks really. Good..

[RAFster122s]

Very nice Jimmy! The tail mini rack is commercial and was what, a top box mount?  Doesn't look large enough to call it a rear rack.

Thanks for the feedback and input everyone.

David

[FunJimmy]

Nice job and handy to lift the whole bike.  ... Not gonna have any give in crash. Looks really. Good..

Thanks Frank.
Let's hope I never have to test that crash worthiness of it.

[FunJimmy]

Very nice Jimmy! The tail mini rack is commercial and was what, a top box mount?  Doesn't look large enough to call it a rear rack.

Thanks for the feedback and input everyone.

David

Thanks David,

The rack is made for a top box by SW-Motech.
I just made the aluminum backrest and support.

[scottly]

1+ about very nice, Jimmy. I like the button washers for the flat head fasteners, and the way you matched the angles of the base. How did you bend the parts? Is the finish paint?   

[FunJimmy]

1+ about very nice, Jimmy. I like the button washers for the flat head fasteners, and the way you matched the angles of the base. How did you bend the parts? Is the finish paint?

Thanks Scottly. All the parts are anodized. i love anodized aluminum, but it's a pain cause you have to finish it really nicely or even small marks show. The button washers where SW-Motech's. I just copied them for the pad rotation head.

I used to bend aluminum in the vice with alloy soft jaws, a block of wood or plastic and a rubber mallet. Works ok for smaller parts but I made an aluminum oil tank for my Buell and needed a better (long) bender so I made this one. There are two top clamps shown in the pic. One for heavy gauge material to 90° and the other for larger angles.

C