cleaning up after the bandsaw

wawoodman

himself, himself
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Mar 19, 2011
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Hi, there.
A real newbie question: After I bandsaw a piece of steel or aluminum to rough shape, what is the better way to smooth and square it up: Hold the cut surface vertical and use a face mill, or horizontally, and use an end mill cutting on the side? Or is there something better?

I could swear I saw a youtube video about this, but I was looking for something else at the time, and didn't watch it. I haven't been able to find it, since.

Thanks,
Mike
 
Let your common sense be you guide, for the most part. Obviously, a sawed piece 36" long won't be practical standing up in a vise. The cross section shape of the material will be part of the decision as well. Angle iron as opposed to round stock for instance. Round stock usually is treated best on the lathe. Also, what the nature of the part you are making can be a factor. Is this a finished face that needs to be very square and true, or is it a cosmetic issue? The cutting tools available need to be considered as well. Do you have a face mill if it is a large cross section? Or will you need a long flute length end mill to get it done? Can you, or should you combine the truing up operation with another, secondary cut?

What shape are you wanting to know about, in particular? If you'll give us that, we can be very specific as to our preferred methods.
 
For example, suppose I want to cut an L shape, with 3/4 inch legs a couple of inches long, out of a 1/2" thick piece of cold-rolled steel. Say I've already milled the outside edges true. I make the inside cuts on the bandsaw. Now, how would you face off those cut sides, so I get a nice, parallel edge? I can use a face mill, I know, or an end mill, if I have the cut edge facing up. And do you just approach the corner very slowly, and then finish it by using the mill side-to side?

I've been a woodworker for 45 years, and I'm just learning all these new techniques!

(Hypothetical, at this point. Just looking for general guidelines, if there are any!)

And a second question: what is it called when you cut a slot in a piece, when the slot goes all the way through, but not all the way to the ends? Like the stop screw on a spring-loaded center, for example, where the stop screw is attached to the inner piece, and slides in and out. Is it a pocket slot, or something like that?

Thanks,
Mike
 
Your example leaves 1.250 length on the inside of the legs. If I were doing it, I'd place the work in a vise on top of a parallel with just enough proud of the jaw to make the finish height (width) of .750. Then using a reasonably large end mill, like .750, take a cut on the end of the piece to make the 2.000 leg length, move over to the side of the upright leg and crank up to cut the finish height (width) of the other leg. A .750 end mill will have sufficient flute length to cut the inside of the vertical leg. This will ensure that the two inside surfaces are as square as the machine axes.

Of course, this assumes that roughing passes that are needed are made prior to finish passes. If you wanted the same finish on both legs' inside surfaces, simply flip the piece the other way and make the required cut, staying just off the opposing surface.

A slot as you describe would be called a blind through slot.

This only applies of you can't have any radius in the inside corner. There are other ways if you can.
 
Mike

There are so many ways to skin a cat!

Unlike woodworking though, where you can often hold the part by hand and feed it into a router bit, or use a freehand router and clamp the stock, with metal you have to make sure that everything is clamped up solid. Often the set up to make a 30 sec cut can be in the hours.

You need to clamp the stock so that there is room, under, over and around where the cut needs to be made. You have to watch that you do not clamp over "air" so that something does not get bent in the clamping, and the cutter has enough room to travel.

Look at some of the online machining videos, MIT, Harvey Mudd College etc for ideas. Get ahld of the Darrell Holland series of videos as well.

Use common sense and remember that if it has a chance to kick back, like you would see with a table saw or woodworking shaper, it will have a lot more force behind it as a metal working operation and the chances of kickback have to be removed by proper clamping and fixturing.

In your scenerio number 1, I would space my pieces up off the table on parallels, reference or indicate the x and y axis to the sides that has already been milled straight. I would then use a side mill operation to clean up the inside two edges that had been bandsawn to rough shape.

on question # 2 a slot is a slot and it does not matter if it comes out to an edge or is closed at either end.

Walter
 
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