RFQ on simple part...

[nate]

Hello all.

I need a quote for a piece of 6061 aluminum with 20 slotts milled into it.

let me describe the part. 5"x7"x3" lets call 3" the height. 5" the depth and 7" the length. i need 20 .125" slots milled along the length (7inch long slots) spaced .125" apart. these slots have to be 2" deep. their is one spot inn the very center of the part which cannot have slots. this needs to be a portion of the billet that is 1.250"x1.250" square.

so if you use the bottom left corner of the billet as the refrence point, the center point of the 1.250"x1.250" space with no slots would be 3.5 inches in from the left and 2.5 inches in from the bottom.

one other thing- the bottoms of the slots must not have 90degree edges. a ball nose endmill could be used or just radiusing the corners of the end mill or slotting cutter will suffice. my requirement here is that their is a minimum of a .010" radius at the bottom of the slots. obviously that would be on both sides. a full .125" radius would be fine too as that could be done with just a .125" ball nose endmill. 90degree corners must be avoided due to stress generated by vibration on this engine. i would like to avoid a cracking of the head at the bottom of the slots- hence the need for a radius.

I only need one of these parts made.

having this part made by the end of april is mandatory.

please quote price with the cost of the 6061 aluminum block included.

please quote asap as i need to have this project started fast.

email quotes to-

nate foerg

destinationroom101@comcast.net



it may help to know that this will eventually be an aircooled cyllinder head.

cyllinder stud holes, combustion chamber and plug threads i can do myself on my equipment. i dont have the capability do do 2" deep slotting.

[Ken_Shea]

Huston, we have a problem
There is no way I know of to mill .125 2" deep, you could post this on the RFQwork forum under EDM but knowing little about EDM even this may be a problem with the center section, maybe have it cast ???


Ken

[nate]

to cast i would have to build a positive first. seems really labor intensive.

i used to work in a shop that did lots of edm work and this part could be burned by plunging. that would require first machining the oposite of the part in graphite.

what i was thinking was that someone with a large sturdy cnc mill could mill the slots with a 3" long .125 carbide endmill by taking .005"-.025" deep passes. if the cuts were coolant flooded, it could be set to just run passes until it got down to the 2" depth.

is this more dificult than i think it is?

[dkowalcz]

Would it be ok if it were done on a horizontal mill? Can you handle having the radial runout for the cutter near the edges of your "keep out" square? This would make it a lot easier to build.

[Ken_Shea]

Nate,
In this case a nice sturdy mill is not much going to help, the problem is with the required diameter and length of the end mill, too small, too long, it just wont work any way I can imagine.

dkowalcz may have hit on a solution though, with using a saw in a horizontal mill.

[Geof]

Originally Posted by dkowalcz Would it be ok if it were done on a horizontal mill? Can you handle having the radial runout for the cutter near the edges of your "keep out" square? This would make it a lot easier to build.

The cutter would have to be around 6" diameter to get a 2" depth so the radial runout would extend to the edge of the part, or beyond.

[nate]

the uncut portion in the middle could be just 1.5" higher than the base that would mean that the slots where they pass over the center 1.250x1.250 area are just .5" shallower than the rest of the slots.


this would make those middle slots having a large radius that is tangent to the edge of the... darn it. i am having a hard time explaining this. is their some free program that i can download that wil allow me to draw a print for you guys??

[CJL5585]

Originally Posted by nate is their some free program that i can download that wil allow me to draw a print for you guys??

A9CAD

It is a cad that is similar to AutoCad. It is shareware. It is not 3D.

Think the site is www.a9tech.com

Hope this helps,
Jerry

[dfry]

Nate,

Sent you an e-mail

Devin Fry
F&F Machine Works

[dkowalcz]

Well, lots of good discussion here... I have one more question/observation that might help:

Are you really sure you want 1/8" slots 2" deep? I've designed a few heatsinks for electronics, and although I'm a bit busy to get the handbooks out right now about fin optimization, I'm pretty sure that unless you're forcing the air, a 2" high fin 1/8" wide with an 1/8" slot won't work really any better than a 1" high one owing to the boundary layer in the slot.

In other words, the air doesn't do a whole lot at the bottom, it's at the top where the action is. Hope this doesn't seem insulting, it's just that making a decent heatsink isn't a matter of "put mo' fins", the heat conduction capacity of the fins needs to balance out with the capacity of the air space to remove it.

[Ken_Shea]

Nate,
Does this look like what you are after, the spacing math will need to be adjusted a bit as you can see but is the look about right

[nate]

well, this whole conversation is really informative.



to answer the question about heatsink design-
this is an aircooled cyllinderhead for a racing lambretta (classic italian motorscooter)
the head is roughly based upon the dimentions of an yamaha rd350 cyllinder head.
it is a "forced air" desing. ie: driving forward forces air into and over the head.
surface area is whats critical here. were it not forced air cooled i would be working with a different fin design.




about the sketch-
its really close. the only thing is that the un-slotted portion is in the middle of the part.




more about the part-
i can make the slots bigger. and have less fins. 15 is the minimum number of fins i want to have. i am going to try that cad program and get a drawing for you all.

its looking like horozontal milling would be the best option so far.