Newbie here, Project advice needed.

[PeteW]

Hey there, I'm new to this forum and I'm new to any type of metal milling work. I have no milling experience, but I do have access to milling equipment at a maker space in my area. I want to make some copper busbars to connect cells for a lithium battery I'm building. I'm using 1/8" x 3/4" x 36", 110 Copper bar stock. I plan to cut the bar stock into 3-1/2" and 4-1/2" lengths for the busbars. Then I want to add 1/4" x 3/8" slotted holes centered near the each end of the busbars to fit over the 6mm cell terminals and still allow some expansion room so as not to stress the terminals. Is a 1/4" 3 fluted square end mill the right choice for this? What is the best way to cut my bar stock into equal sizes using a band saw? I'm thinking band saw for a thinner blade kerf, than my table saw or my miter saw. This is important to me because, if I'm correct, it will allow me to get (10) instead of (9) 3-1/2" busbars from a 36" bar stock.

 

[rabler]

For cutting, if your maker space has a horizontal bandsaw that will work well. You can clamp stuff in a horizontal bandsaw for cutting. Copper has a tendency to grab/stick to drills, saw blades, etc, to be sure to clamp in and do not try to hold it by hand while using power tools on it.

 

[markba633csi]

I second Rabler, copper is one of the "tenacious" metals and can grab tools if you are not careful. Drill holes to finish size in one pass, no pilot hole.
Also be careful milling it, be sure it's clamped down securely and protect yourself in case it comes out of the vise. I'd use a 4-flute endmill.
Be careful around lithium batteries too, they have a large energy density and can do a lot of damage if shorted or overheated.
-Mark

 

[rabler]

... and welcome to the forum!

 

[Nutfarmer]

Don’t forget hand tools. It can all be done by hand. For the slots, drill and finish with a file. It would take longer, but if access to machines is limited there is always a work around.

 

[PeteW]

For cutting, if your maker space has a horizontal bandsaw that will work well. You can clamp stuff in a horizontal bandsaw for cutting. Copper has a tendency to grab/stick to drills, saw blades, etc, to be sure to clamp in and do not try to hold it by hand while using power tools on it.

Thanks for the warning and the welcome! In my research I've read articles and watched some Youtube videos that have all said the same thing. Actually, they do have have a horizontal bandsaw, but during what was a fairly brief inspection I did not see any way to set it up to make repeatable cuts. Is there a way to do this?

 

[PeteW]

I second Rabler, copper is one of the "tenacious" metals and can grab tools if you are not careful. Drill holes to finish size in one pass, no pilot hole.
Also be careful milling it, be sure it's clamped down securely and protect yourself in case it comes out of the vise. I'd use a 4-flute endmill.
Be careful around lithium batteries too, they have a large energy density and can do a lot of damage if shorted or overheated.
-Mark

Thanks Mark, I usually do use a pilot hole and even do progressive drilling with metal, but as you said, and I keep learning, copper is a sticky metal, so I'll take your tip to heart.

With regards to endmill bits I did not find a lot of information about the best type of endmill bit (flute wise) for copper. In a couple of videos I watched I thought they we using 2 flute and also very aggressive 4 flute bits (but made for hulking out large areas), but they were hollowing out large spaces, nothing like I'm doing. I also read that 3 flute bits were nearly as good as a 2 flute bit for clearing chips (which I understand is good for copper and aluminum) and was also a bit stronger. So, I ordered a 3 flute simply based on not finding to much directly helpful information.
This is not a problem as I can return it. I would really appreciate it, if you don't mind educating me, if you could explain to me why the four flute makes sense in this application.

I didn't bring it up before, but I'm also going to mill some aluminum stock to make some (just about 4) strut channel nuts to hold down some solar panel clamps I'm mounting to some aluminum strut channel. I'm going to need to cut some narrow groves in them to help keep them from twisting inside the channel. This last part can certainly be a different discussion and thread.

 

[PeteW]

Don’t forget hand tools. It can all be done by hand. For the slots, drill and finish with a file. It would take longer, but if access to machines is limited there is always a work around.

Making do is one of my specialties! In this case though I'm really hoping to turn out something that is more on spec and won't cause me to fuss later. Plus, I really like to finish this in this lifetime.

 

[markba633csi]

I haven't cut any copper lately (except wire) but I believe the 4 flute would be less likely to grab the part and pull it out of the vise. Also it should give a
nicer finish but that may not matter in your application
The 3 flute should be ok

 

[Winegrower]

Actually, they do have have a horizontal bandsaw, but during what was a fairly brief inspection I did not see any way to set it up to make repeatable cuts. Is there a way to do this?

It’s likely that the bandsaw will have an adjustable stop that you can set. If not, you be able to kludge up a stop with whatever bar stock and C clamps you can find.