Cutter flute lenght for Aluminum

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criznach
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Cutter flute lenght for Aluminum

Post by criznach » Sun Mar 09, 2014 6:17 pm

I'm going to attempt to cut new spindle mounts from 1/2 inch aluminum. I found a nice end mill for aluminum on ebay a while back, but the flutes are only 3/8 long. I'm doing a test to measure my runout in 1/4" and it's working great so far.

http://www.ebay.com/itm/380824507246?ss ... 1497.l2649

Will it cause problems to cut 1/2 inch depth with this bit? My worry is that there might be some rubbing of the material against the shank in the last 1/8".

jland
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Re: Cutter flute lenght for Aluminum

Post by jland » Sun Mar 09, 2014 11:09 pm

Being ground from the shank, the cutting edges are a little smaller in diameter than the shank size, so you can get some rubbing. You could make an extra pass on the top 1/8 to create some relief.

Brian
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Re: Cutter flute lenght for Aluminum

Post by Brian » Mon Mar 10, 2014 12:09 am

criznach wrote:I'm going to attempt to cut new spindle mounts from 1/2 inch aluminum. I found a nice end mill for aluminum on ebay a while back, but the flutes are only 3/8 long. I'm doing a test to measure my runout in 1/4" and it's working great so far.

http://www.ebay.com/itm/380824507246?ss ... 1497.l2649

Will it cause problems to cut 1/2 inch depth with this bit? My worry is that there might be some rubbing of the material against the shank in the last 1/8".
You'll deffinitely have issues with rubbing and deflection of the cutter which will decrease accuracy. Also when your rubbing that bit at 20k+ rpm its going to make a ton of heat. I wouldn't reccomend trying this. You can find reasonably priced carbide endmills that have the appropriate depth for what you need. The other issue you will run into is chip clearing. I would deffinitely have some kind of and air nozzle to blast the chips out of the deep profiles as it'll gum up really quick.
Brian
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criznach
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Re: Cutter flute lenght for Aluminum

Post by criznach » Mon Mar 10, 2014 12:17 am

Thank you. Very good info. I've considered cutting a wider relief channel so I don't get rubbing, but I need to make the surface that joins the steel plate be flat. Maybe I could put it on the disc sander... Or maybe I'll just hold out for a 1/2" depth cutter. I'd have just bought 3/8" material, but my local supplier doesn't stock it. The 1/2" piece I got was from their scrap bin.

WillAdams
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Re: Cutter flute lenght for Aluminum

Post by WillAdams » Mon Mar 10, 2014 12:40 am

Why not cut it out in halves, flipping it over after making the cut half-way through?
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criznach
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Re: Cutter flute lenght for Aluminum

Post by criznach » Mon Mar 10, 2014 1:00 am

WillAdams wrote:Why not cut it out in halves, flipping it over after making the cut half-way through?
I thought about that too but I don't know how I would accurately position it. I've had good luck with the tabbed fixtures in wood, but I'd need to cut all the way through to do that.

WillAdams
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Re: Cutter flute lenght for Aluminum

Post by WillAdams » Mon Mar 10, 2014 1:17 am

My suggestion would be:

- cut out the shape / size of the material from a piece of MDF (you'll probably have to relieve the corners
- move the gantry out of the way using commands and leave it powered up so it maintains position
- insert the aluminum, clamp, cut one side
- move the gantry out of the way using commands and leave it powered up so it maintains position
- flip the aluminum, re-clamp, cut a mirrored image of the first cut
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fishtoprecords
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Re: Cutter flute lenght for Aluminum

Post by fishtoprecords » Mon Mar 10, 2014 1:41 am

criznach wrote:I thought about that too but I don't know how I would accurately position it.
Drill a couple of alignment holes in the part (in the waste area) and into your wasteboard. Put pins in them. Machine one side, flip and align on the pins.

If you want to be really serious, you can ream the holes to a precision size. Normal drill bits only drill a nominal size.

danimal
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Re: Cutter flute lenght for Aluminum

Post by danimal » Mon Mar 10, 2014 3:15 am

The single flute up-cut end-mills from inventables are cheap, and seem to work well on aluminum with cooling. You will need to use some water or WD-40 as coolant / lubricant. Definitely hold out for an end mill with the correct cutter depth. It will probably turn out badly if you go for it with the one that you have. It would suck to have 1/16th left to cut through and snap your end mill. Flipping and indexing will work, but it is a lot more work. I only do indexing and rotation when there is no other way because it is very tedious and takes a lot of setup and additional material. It would be much cheaper and easier to just buy the longer end mill and then you have a backup later for thinner milling of aluminum. You will break end mills on aluminum.
Last edited by danimal on Mon Mar 10, 2014 3:20 am, edited 1 time in total.
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Brian
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Re: Cutter flute lenght for Aluminum

Post by Brian » Mon Mar 10, 2014 3:19 am

EBay has all kinds of endmilla that you can use. I personally order from JTS machinery, good prices and good selection. You can get a nice 2 flute coated endmill that'll be deep enough for under $12 iirc. They have an eBay store for quick ordering.
Brian
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