Does this look like it'll work?

[sdelivery]

I see your just trying to remove a large peice that could be quite desirable in the near future instead of just turning it into chips.
First I would rather use a saw but you might not have one available so I like the slitting saw for this purpose because of the design verses a small end mill. It would likely break.
Speed Kills- You should think about a spray bottle with the appropriate coolant.
I would like to see a stop on the table at the bottom of the part in the direction you intend to feed in.

 

[sdelivery]

Another thing I just noticed is the face you intend to cut on is "lumpy "
I would touch the cutter off on the highest mountain set zero back away and start your first pass from that touch off. Increment in until you are cutting all the was across, it is tempting to touch off on the lowest valley but that could have the cutter deeper than it cares for when you hit a mountain.
Kerosene is good coolant for cutting cast iron.

 

[jwmay]

You are correct. I should have a nice 9"x1"x3/4" rectangle of cast iron for myself when I'm done. Instead of a big pile of black dust.
I should have waited, but I got started already by chain drilling inside one of my layout lines to about .030" shy of full depth. I did break a drill bit. So now I'll have that to contend with as I move forward.
I do have a pretty good horizontal bandsaw, but it balks at 9" long cuts. It's a 7x12, but I kinda think they're talking about square tube when they give those numbers. 2x4 seems to be the most it'll take. And the down feed cylinder isn't working right, so I'd have to lower it by hand.
I do have a small block of material clamped in the corner to counteract cutting forces, but I may not have gotten it in the picture. Keep 'en coming guys! I might just succeed in this after all!

 

[jwmay]

Actually I just put a new blade on the saw. I probably should have started there. And it's a TIN coated HSS milling cutter. I didn't buy it on purpose, but since I have it, it was a thought. I was nervous about it for my little machine, so figured I'd ask.
I'm going to revisit the bandsaw idea.

 

[Winegrower]

I think most of machining is giving it a shot in a non-destructive way, see what happens, correct and repeat.

 

[682bear]

If you proceed with the slitting saw, I would advise running the slowest speed possible, DOC at .100, and start at a low feedrate... after it begins cutting, bump the feed up until it just begins to chatter, then back down until the chatter stops...

I don't know what type of mill you have... the DOC may be too much, or you may get away with more... I'm a 'try it and see, then adjust as necessary' machinist... or a 'seat of the pants' machinist if that makes sense...

One thing that hasn't been mentioned... if the part is a rough casting, the outer surface may be extremely hard. If so, you may very well scrap the saw no matter what you try... It would be better if you could get the speed down to 60 or 70 rpms.

Good luck...

-Bear

 

[Doug Gray]

In the mill setup shown, spindle stick out is huge. I always have my spindle completely retracted and lock when milling...no? Im talking smaller l r8 mill/drills.

 

[jwmay]

Yep. That is a lot of spindle hanging out. I'll adjust that. At the time of setting it up, I wanted the head up high. I was planning to cut that slot, and then chain drill the top surface without having to move the work or the head elevation.
Thanks again! The whole plan seems to be evolving.

 

[mattthemuppet2]

I'd definitely go with the bandsaw first. You'll probably need to turn the piece around to cut from both sides, then finish the bit in the middle with a hand saw. It's a lot quicker, less effort and you're less likely to break something. Slitting saws take a bit of getting use to.

 

[jwmay]

This was a good idea. Thanks!
I've been using this vise as ballast for my mill/drill for 4 years. I'm glad I finally found a better use for it.