[flojor10]

I'm making a cast iron part on my cnc router for the first time and was wondering if this 1/4 Hanita Varimill 4 Flute endmill is good, the sellers description looks a little too promising to me:bs:. Has anyone had experience with these, and can tell me feeds/speeds and whether to machine with or without a coolant?

Thanks, George

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[ger21]

Are you cutting cast iron with a router?

[flojor10]

Yes, my cnc router is very well built though it has acme lead screws, anti backlash and supported rails, I've already machined aluminum with success.

[Geof]

Cast iron is very different to aluminum. With a 1/4" diameter cutter on aluminum it is possible your router would not be able to go too fast because the surface feet per minute can be in the thousands. On cast iron it is very likely you will not be able to go slow enough because some casts irons need a speed as low as 50 feet per minute. Also different cast irons are very different in their machinability. El cheapo run-of-the-mill cast iron used for cheap import machines can vary from being very easily machinable all the way up to glass hard; all in the same piece.

Good luck if you do try it but expect to burn away a few tools during your learning curve.

[flojor10]

I'm going to mill 1" cast iron flat from Speedy Metals.com, is that a quality manufacturer?

[Geof]

I had a look at the link and it seems you have gray cast iron. Then I went further in that site and found this; Machinability of Class 40 Gray cast iron is good with average cutting speeds at 700 sfm and finishing speeds as high as 1,400 sfm. which I find unbelievable! However, it would seem you are not going to experience too many problems.

I do suggest you start at less than 700 sfm and if you find, eventually, that you can run at 700 sfm then I guess I will have to accept I am just too old and out of it.

[UUU]

Cast iron can be abrasive and wear high speed steel endmills quite quickly. So a carbide one like the one in your link is likely to be better. I've no idea if the "varimill" features would make this one any better than another.

I prefer to machine cast iron without coolant.

Continuous cast bar is nice stuff to machine, although I've only used a mill not a router. Rough castings can have an abrasive surface skin that you need to get beneath with your first cut, and can have hard spots.

[Mountaincraft]

Are you saying you can cut cast iron with a cnc router?

Wow.. please post youtube video if possible...

[flojor10]

Cast iron can be abrasive and wear high speed steel endmills quite quickly. So a carbide one like the one in your link is likely to be better. I've no idea if the "varimill" features would make this one any better than another.

I prefer to machine cast iron without coolant.

Continuous cast bar is nice stuff to machine, although I've only used a mill not a router. Rough castings can have an abrasive surface skin that you need to get beneath with your first cut, and can have hard spots.

The cast iron I ordered is a continuous bar, so I shouldn't have a problem with a rough skin, thanks for the heads up though:cheers:. After a bit of research I found out the endmill is carbide and I think that they are even TAin coated due to the grayish discoloration on the tip of the picture on ebay:banana:.

Thanks Geoff for the machinability information:cheers:, it's great I found some quality cast iron that hopefully I will be able to machine. I just don't know if my 1hp router will work, since it only goes 9,000rpm on low setting. Also does anyone know the depth of cut I should try on cast iron?

[louieatienza]

I think even 9000rpm is too fast, considering the 4-flute design. I believe these are designed for high speed machining on a VMC. That said, with your spindle HP, you probably have to take very light passes at a relatively high speed, but then you'll wear the tip out way before the edges...

[UUU]

In a chunky mill, you'd run that tool 1/4" deep and 1/16" stepover. Only for the brave.

But I think the principle holds true, that it's better to cut deeper with less stepover than a shallow, wide cut. Otherwise all your cutting is done on the very tip rather than the sides. (I know they're called end mills, but they're not designed for facing, they're for profiling). Your router rigidity will be tested! You'll have to experiment to see what she'll take.

The 9000 rpm is way too fast, but cast iron is forgiving stuff - it's nowhere near as scary as steel. If you can get the feed rate up, you'll get shiny slithers off, but at a lower rate, mostly black dust.

I look forward to seeing if you can prove the doubters wrong.

[ger21]

Please video the first attempt.

[dertsap]

these used to be one of my favorite tools , the hanita variable flute mills are designed for full engagement full depth cuts ,and they're designed for high speed machining , they can handle a fair bit of abuse ,
in your case if you take light depth of cuts, light engagement and a fairly heavy feed then you should be able to make it work , as long as you can create a fairly optimal tool path , the thing to keep in mind is that you don't want to create enough heat to burn the coating , there is a misconception that coated tools are only to be run dry , but the truth is its on a case to case basis , so if you can use enough coolant to keep it cool then use it , otherwise if you've got compressed air then run an airline to air blast the tool .
ive always seen it said that steel can't be cut with a router so i did a rough test to prove that theory wrong , i also wanted to test the power needed for trochoidal machining , if you move to the middle of the video you'll see that its cutting at 120 ipm , keep in mind that this was only for fun and test purposes , so its nothing pretty

[ame="http://www.youtube.com/watch?v=s1ftb_cA4nE"]cutting steel - YouTube[/ame]


.

[flojor10]

these used to be one of my favorite tools , the hanita variable flute mills are designed for full engagement full depth cuts ,and they're designed for high speed machining , they can handle a fair bit of abuse ,
in your case if you take light depth of cuts, light engagement and a fairly heavy feed then you should be able to make it work , as long as you can create a fairly optimal tool path , the thing to keep in mind is that you don't want to create enough heat to burn the coating , there is a misconception that coated tools are only to be run dry , but the truth is its on a case to case basis , so if you can use enough coolant to keep it cool then use it , otherwise if you've got compressed air then run an airline to air blast the tool .
ive always seen it said that steel can't be cut with a router so i did a rough test to prove that theory wrong , i also wanted to test the power needed for trochoidal machining , if you move to the middle of the video you'll see that its cutting at 120 ipm , keep in mind that this was only for fun and test purposes , so its nothing pretty

cutting steel - YouTube


.

How did you get your endmill to make circular cuts in the video? Is there advantages to doing this, and in cambam is it possible to do this?
Thanks for the advise it's very apreciated, George

[dertsap]

I don't think that cambam can create those types of paths , that path was hand coded and is simply a looped sub routine , heres some info regarding the advantages of those types of paths Advanced Toolpaths Improve Cutter Performance in Difficult Materials : MoldMaking Technology

[flojor10]

I don't think that cambam can create those types of paths , that path was hand coded and is simply a looped sub routine , heres some info regarding the advantages of those types of paths Advanced Toolpaths Improve Cutter Performance in Difficult Materials : MoldMaking Technology

I actually found a trochoid milling add on for cambam. I will have to experiment with it when I get the cast iron!


http://www.cambam.info/ref/plugin.cadextras

[dertsap]

COOL
he certainly doesn't stop in the development of that software .
i may just have to buy a license one day , a guy can never have too much software

[LeeWay]

I have a pretty rigid router setup as well. Before my mill was completed, I milled quite a bit of aluminum in it. The cuts were acceptable, but my issue was heat in the router as well as tiny chips getting into the motor housing. You may also find that runout of the router itself may be an issue with carbide tools in hard material. They can't take much chatter. If that is the case with yours, then HSS might be a better choice. It is not as prone to tip breakage.
So watch the heat, chatter and chips and let us know how it goes.
I have ordered a couple cast iron block from Speedy Metals, but all I had to do was bore them out to use as tool holders on my lathe. That was no problem at all. Cut like butter.

[UUU]

For steel or stainless, I'd endorse the use of HSS. But for cast iron, I find it wears really quickly, so I prefer carbide. But it is more brittle, and I've broken a few cutters with mistaken G0 instead of G1 - perhaps that's asking too much of any tool!

Talking of chips getting into the motor - as noted before, you get a lot of dust off cast iron, so you may need to shield the motor.

[dertsap]

its most likely that hss end mills will not handle the high rpm