Deep Deep Pocketing issues

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01-20-2013, 11:14 PM
Dsmed

Deep Deep Pocketing issues

Hello all, got a question for the experienced. I have been running my 1100 since May 2012 and its been exceeding my expectations since day one. Currently I am designing a new intake manifold for some drag/street cars and it requires quite a bit of machining of deep holes. The intake runners to be more specific. They are 3 1/2 inches deep and have some contours inside so drilling is not an option. Another part also requires me to do some (alot) of machinning at almost 5 inches deep. Both parts require I use a bit that is no bigger than 3/8 in diameter and a straight shank.

Now I ordered a Multi-Master carbide shank from Iscar that allows you to mount intechangable tips. It is 7.5 inches long and currently I have purchased end mill bits for it that are a 2 flute square cut specifically for aluminum. The parts are being made from 6061. And I have terrible chatter no matter what doc and ipm i try. I have tried 0.005 up to 0.040 doc and varied ipm from 5 up to 35. The finish is almost identical regardless of what settings I try. I tried spindle speed of 3800 up to max speed and also tried climb and conv milling.

Now I also have some cheap 6 inch long 1/4 dia. bits from shars that I have used here and there and tired a couple tested. Now the shars bits are ball nose not square. And I have one that is a 2 flute and one that is 4 flute. And the 4 flute will chatter a bit at lower ipm around 5-8. But once I get it up past 9 ipm it smooths out to almost no chatter and the finish is acceptable. I am considering ordering some either ball nose 4 lute bits for the Iscar tool holder or trying some 4 flute square end bits for the holder. But at about $80 each and you have to buy them in quantity of 2 I would rather hear from an expert what would be the better choice to order.

Sprutcam said the part will take 14+ hours to make with the 1/4 inch ball nose from shars, and after about 8+ hours the bit snapped. Which was to be expected from a $18 bit with over 4 inches of overhang. So we spend several hundred for the Iscar tool to get a better quality tool and speed up the production with a wider tool. But currently we are stuck with extreme chatter which I know If I keep running it like that the new holder will break very soon from the vibrations.

Any suggestions or ideas would be appreciated.

Also flipping the part is not an option.
01-22-2013, 03:16 AM
kfwittekiend

I currently am using a 3/8ths coated carbide end mill sticking out 4 inches to pocket the middle holes in some of the muzzle brakes I make. I was getting the terrible chatter until I reduced the spindle rpm to 3000, .050 DOC, and 10ipm feedrate. Running at this speed the end mill is quiet and leaves a good finish. This is in 416 stainless, but something close should work the same for aluminum.

I've noticed that if I try to baby one of the carbide end mills they will chatter, it needs to be set at the correct feedrate.

I also bought a subscription to G Wizard that has helped quite a bit.

Ken
01-22-2013, 05:52 AM
magnum500sw

Quote:

Originally Posted by kfwittekiend

I currently am using a 3/8ths coated carbide end mill sticking out 4 inches to pocket the middle holes in some of the muzzle brakes I make. I was getting the terrible chatter until I reduced the spindle rpm to 3000, .050 DOC, and 10ipm feedrate. Running at this speed the end mill is quiet and leaves a good finish. This is in 416 stainless, but something close should work the same for aluminum.

I've noticed that if I try to baby one of the carbide end mills they will chatter, it needs to be set at the correct feedrate.

I also bought a subscription to G Wizard that has helped quite a bit.

Ken

so what is your question ?
01-22-2013, 06:00 AM
magnum500sw

Quote:

Originally Posted by Dsmed

Hello all, got a question for the experienced. I have been running my 1100 since May 2012 and its been exceeding my expectations since day one. Currently I am designing a new intake manifold for some drag/street cars and it requires quite a bit of machining of deep holes. The intake runners to be more specific. They are 3 1/2 inches deep and have some contours inside so drilling is not an option. Another part also requires me to do some (alot) of machinning at almost 5 inches deep. Both parts require I use a bit that is no bigger than 3/8 in diameter and a straight shank.

Now I ordered a Multi-Master carbide shank from Iscar that allows you to mount intechangable tips. It is 7.5 inches long and currently I have purchased end mill bits for it that are a 2 flute square cut specifically for aluminum. The parts are being made from 6061. And I have terrible chatter no matter what doc and ipm i try. I have tried 0.005 up to 0.040 doc and varied ipm from 5 up to 35. The finish is almost identical regardless of what settings I try. I tried spindle speed of 3800 up to max speed and also tried climb and conv milling.

Now I also have some cheap 6 inch long 1/4 dia. bits from shars that I have used here and there and tired a couple tested. Now the shars bits are ball nose not square. And I have one that is a 2 flute and one that is 4 flute. And the 4 flute will chatter a bit at lower ipm around 5-8. But once I get it up past 9 ipm it smooths out to almost no chatter and the finish is acceptable. I am considering ordering some either ball nose 4 lute bits for the Iscar tool holder or trying some 4 flute square end bits for the holder. But at about $80 each and you have to buy them in quantity of 2 I would rather hear from an expert what would be the better choice to order.

Sprutcam said the part will take 14+ hours to make with the 1/4 inch ball nose from shars, and after about 8+ hours the bit snapped. Which was to be expected from a $18 bit with over 4 inches of overhang. So we spend several hundred for the Iscar tool to get a better quality tool and speed up the production with a wider tool. But currently we are stuck with extreme chatter which I know If I keep running it like that the new holder will break very soon from the vibrations.

Any suggestions or ideas would be appreciated.

Also flipping the part is not an option.

myself , i would not use a ball nose on that . i would use a flat or something with a small corner rad . but thats me . you will notice there will be a hundred replies and a hundred different replies .