Help with Cutting Thin Slits in Sheet Metal


#1

I have a project where small, 1mm (preferably .7mm if possible) slits, 6.5mm across are required in piece of sheet metal. The hard part is that they do not intersect any of the edges to allow sawing in from the sides. I was wondering what would be the best way to accomplish this.

The slots are then popped up to create vertical “air scoops” which is seen on the right side of the image.

Any advice is appreciated. :slight_smile:


#2

You could have someone do it with a metal laser.


#3

If I were you I’d do it w/ the Bridgeport. You’ll have to buy an end mill, though. You can get a 1mm slot w/ a 1/32" EM, many of which have an 1/8" shank that we have collets for. You’d have to go smaller than that for a 0.7mm slot. You’ll have to go slow to avoid snapping the EM.


#4

If you do try with the Bridgeport, make sure you adhere the piece to a thick substrate so that you can hold it properly. The best option would be a metal fixture plate, but you can get by with mdf if you don’t use any cutting fluid.

Double sided tape is your best bet for holding the metal to the substrate. I believe Bryan has some in the machine shop.


#5

It sounds like what you are creating is (very small) louvers (I’m sorry that I’m not competant to read your attached schematic).

Here are some macro-louvres being made with a homemade tool.Maybe do this on a more micro-level?

Effectively, stamp them with a formed stamping tool.

EDIT: Just realised, in your attached schematic, is the tool. It looks like a needle (hypodermic style, but not hollow).


#6

I’d be interested to know how this build goes.
What about a making a punch? Or just using a different design. If I recall correctly, the last gas turbine combustor plans I looked at didn’t have those features


#7

You beat me to it. I was going to say louvers as well.

This is one way that I found, there are other ways as well but we don’t have at the space besides what’s already been mentioned. A bead roller with louver rollers would work.


#8

How many do you need to make, and how precise do they need to be? And what is the thickness of the sheet metal? And what kind of sheet metal is it?


#9

If thin gauge metal, a heavy box cutter blade (not a snap blade) and a wooden jig to control the cut might work. It’ll cut through ductwork-gauge steel. Punch through with the tip, then extend the cut.

I imagine you could pre drill start and stop holes first for strain relief when bending.

Use a new blade (or new end yielding 2 cuts per blade) for each cut.


#10

Obviously, I’m guessing, but I think, based on ChrisPatterson’s assertion, that it’s basically this KJ-66 Gas Turbine build: http://www.jmaireland.com/build%20your%20own%20turbine.pdf
That means these need to be in “stainless steel sheet 0.3-0.5mm thick”.
I think HankCowdog’s suggestion is the best so far. I wonder if one of the “xacto knife” blades could work well, maybe mount the whole knife in a drill press for control…


#11

A box cutter blade is much thicker/stronger than an Xacto blade. I would not try to use those thin blades in this manner when handheld.


#12

Actually, I was going to suggest piercing with a small drill bit and then sawing with a jeweler’s saw - fairly coarse blade, number 2 through 5 for instance.


#13

I need to make 6 of them, they just need to be within a milimeter. The sheet metal is .66mm thick. It is weld steel.


#14

It is a KJ-66 jet engine. Thank you for the pdf! It will probably come in handy! :grinning:


#15

Since that is so few slots, and the material is so thin, I do suggest piercing with a small drill bit and then sawing with a jeweler’s saw. That would be quick and easy to do.


#16

It also, isn’t that tough to maintain the accuracy you say you need. Just do a good layout, or even better adherre printout of the layout and cut/file to the lines. (Needle files are cheap and can fit that size).