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How would you machine this casting in one op? Side milling cutters?

Lazyman

Aluminum
Joined
Nov 28, 2016
The part will be some sort of cast granite with steel inserts about 18x18x6 in. The red and blue surfaces are steel inserts and need to be machining. The blue just needs to surfaced with minimal material removal and main importance is squareness and perpendicularity to the red surfaces. Any suggestions for tooling to machine the blue surface so I could do this all in one operation? Any thoughts on side milling cutters to do this in multiple passes?


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I'd bet in the old days they'd cut that on a big horizontal in one pass with stacked cutters on one arbor...

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I would make an "L" shaped fixture and hold the part on the sides and the small side bottom with some sort of wedge clamps.

Then I would use a facemill to cut the blue surfaces, and a slitting saw to cut the red surfaces. Depending on tolerances, this is should work fine.
 
Knowing the machine to be used would be handy.
A really big broach would be very fast and you could pop these out finished in less than 30 seconds each. :)
Tolerances on size and square also, just cleaned up, many thous, a few tenths, microns?
In a VMC or HMC some would consider it one op but multiple tools.
On a big manual mill is doing a few passes up front, moving back and doing a few more still one operation since it is only one clamp?

Part is of decent size, you may want to job it out to someone with machines and tooling on hand.
I wonder what it would cost to just tool up that horizontal above in today's dollars?
Somewhere volume comes into play as to best for the buck. On a 9x42 B-port it's two clamps but maybe cheaper.
Many ways to skin a cat, it can also be done a on a big surface grinder.
Bob

(I know all this not much help but the phrase "cast granite" always says something to me so tossing a penny in the pot for the OP whom I do wish well on this endeavor.)
 
Knowing the machine to be used would be handy along with tolerances on spacing and square.
A really big broach would be fast.
In a VMC or HMC it's still one op but multiple tools.
Part is of decent size, you may want to job it out to someone with machines and tooling on hand.
Bob

Sorry I forgot to mention its on a low hours VF-2SSYT with 18" table and 20" y travel so it just fits the envelope. Tolerance is "best as possible" on the Haas. If its as "square" as my Haas is I'll be happy. Squareness and perpendicularity of the surfaces are top property. Dimensional tolerance on blue surfaces could be plus minus a 1/16" it wont matter as long as they are consistent to each other. It just needs to be flat and square. I will have to do some further testing on desired tolerance. The part is for in-house purposes and may have to make them regularly so I would rather do in house.


I would make an "L" shaped fixture and hold the part on the sides and the small side bottom with some sort of wedge clamps.

Then I would use a facemill to cut the blue surfaces, and a slitting saw to cut the red surfaces. Depending on tolerances, this is should work fine.

You literally mean slitting saws or side milling cutters that typically have more width?

Wheels17, come on man please tell me how to do it these days on a vertical.

Thanks for the help. Any thoughts are appreciated.
 
Repeated depth passes with reduced shank endmill. Flute length should be minimal, e.g. 1".

The idea is that the cutter will flex, but the same amount at every depth pass as to eliminate taper.
 
So 6 inches machined on the blue surface and you want it true and flat?
Necked endmills help much with taper but here is a wild idea for this long area. You can mount a grinding wheel in your machine for finishing if you can afford the time.
Bob
 
I would make an "L" shaped fixture and hold the part on the sides and the small side bottom with some sort of wedge clamps.

Then I would use a facemill to cut the blue surfaces, and a slitting saw to cut the red surfaces. Depending on tolerances, this is should work fine.

a 4" wide slitting saw?
 
I'd use a carbide insert 90 degree cutter on a 6" arbor, should cut both surfaces in one setup. Multiple passes for the 6" depth, then face the shallow surface as needed. Spring passes and some testing will be needed to get the 6" depth to be flat and uniform all the way down. Do some digging into the best, most free cutting cutter, and change out inserts before they dull much.

Something like this: Amazon.com: Accusize Industrial Tools 2'' by 3/4'' 90 Deg Square Shoulder Indexable Face Mill with 5 Pcs Apkt1604 Carbide Inserts, 4508-0012: Industrial & Scientific but from a proper vendor (Sandvick, etc) who can supply the extended arbor with integrated CAT 40 taper.
 
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Something like this: Amazon.com: Accusize Industrial Tools 2'' by 3/4'' 90 Deg Square Shoulder Indexable Face Mill with 5 Pcs Apkt1604 Carbide Inserts, 4508-0012: Industrial & Scientific but from a proper vendor (Sandvick, etc) who can supply the extended arbor with integrated CAT 40 taper.

Indexable carbide insert mills with axial rake can not make perfect 90 walls. It's a geometry problem with the rotational size and the fact that you make one insert to fit many cutters.
There is a sweet spot.
As a designer you live with the belly or cave cut across the product line and fiddle with the axial where you can to make it close.
This is not endmills and is frustrating to get right or even just good enough.
6 inches or so in Z is a long ways for a flat and true surface done on a smaller VMC to tenths.
Bob
 
Indexable carbide insert mills with axial rake can not make perfect 90 walls. It's a geometry problem with the rotational size and the fact that you make one insert to fit many cutters.
There is a sweet spot.
As a designer you live with the belly or cave cut across the product line and fiddle with the axial where you can to make it close.
This is not endmills and is frustrating to get right or even just good enough.
6 inches or so is a long ways for a flat and true surface done on a smaller VMC to tenths.
Bob

Fair point. I started my post with a recommendation for a shell mill, then went to an insert cutter. I guess it's back to a shell mill and arbor. Keep it sharp and program the needed spring passes and it could work.
 
Repeated depth passes with reduced shank endmill. Flute length should be minimal, e.g. 1".

The idea is that the cutter will flex, but the same amount at every depth pass as to eliminate taper.

This is along what I was thinking but perhaps with a shell mill or side miller like these from Maritool.

Straight Tooth Side Milling Cutter 2.5-.250-.875-18 Teeth MariTool

General Purpose HSS Shell Mill 1.750 dia X 1.25 X .750 arbor MariTool

Fair point. I started my post with a recommendation for a shell mill, then went to an insert cutter. I guess it's back to a shell mill and arbor. Keep it sharp and program the needed spring passes and it could work.

I'm definitely leaning toward the shell mill over indexable. I guess I will have to experiment with some steel blanks in a side mounted vise and see what happens.
 
Cast granite? Currently maybe the Philippine island is casting molten stone, not sure if that volcano is pouring granite. Kinda hot work.
 








 
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