This material, These cutters?

[vacpress]

Hey!

So, I purchased this piece of material: http://cgi.ebay.com/ws/eBayISAPI.dll...e=STRK:MEWA:IT

An I am looking at the following 1/4" End Mills to do the majority of routing, and to plunge all the 1/4" holes, of which there are about 30.

4 Flute:http://www.niagaracutter.com/solidca...zer/index.html
0r
2 flute:http://www.american-carbide.com/EndM...ection=6&Cat=1
Cost isnt that different for the various options, so I am a bit lost. I gather 2 flutes evacuate material easier so this will reduce risk of gumming up at the cutter.These will be used on a commercial 48x48x5" gantry router with a very nice spindle. I can only use light spritzes of coolant...


The parts I am hoping to make can be seen in this thread:
http://www.cnczone.com/forums/showthread.php?t=33481

[ger21]

Did you see these at the bottom of your link, for routers? Don't know what would work best, though.
http://www.american-carbide.com/Wood...ection=2&Cat=4

[vacpress]

gerry.

Yeah, thanks for looking out... I was told to just use endmills because they are much cheaper and will 'work as well'...

$38 router bit.. I would purchase it, but I am scared! That is like 4 end mills.

Grr. Options!

[nupeswv]

First of all I would recomend a 2 flute hss endmill with an off center grind on the bottom. This can be plunged much like a drill without chatter. the niagara 4 flute is great for removing material with its side but the bottom is ground to center...meaning a divot is left when plunging like a drill. A 2 flute will work well if you decrease your feeds appropriatly for all the other machining. High helix endmills will leave a little better finish as they are more suitable for aluminum.
I work as a machinist and we do much of our work on aluminum. Unless long runtimes are needed, hss is awesome because they are sharper than carbide. There are specialty 4 flutes that are off center grind that can be plunged but they are more costly.

[vacpress]

nupeSW

thank you very much for your concise answer. i had noticed that these 2-flute end mills in one of my links had an off-center... bottom.. face.. whatever.. i figured that was for plunging.

So I will now order 2 of the 1/4" HSS 2-flute high-helix end mills!

Hooray. In the meantime, Ive got to redesign my parts to have as few hole sizes as possible...

My parts, most of them have some 10-24, and some 8-24 tapped holes. Soon they will be consolidated as much as possible... I think i am in luck, and all of the holes are larger than .125, so i can get away with one inital hole-drilling operation to make pilot holes, and let the 1/4 endmill rough out the 16 or 18 1/4" clearance holes..

[judleroy]

Go to www.Discount-Tools.com and look at there aluma-mills for HSM of aluminum. A 1/4" 2Flute with 1" loc. is around $17.00. They always work well for me.

[vacpress]

judleroy

thanks for the link. so. all these different coatings. I have been reading google pages for some time now. Any recommendation? What type of coolant do you use?

Thanks

[judleroy]

vacpress

I use a flood coolant but sometimes run them dry. If you
look at the "Tech Pages " section at discout-tools you will find all kinds of info. They have a recommended feeds and feeds section just for aluma mills. At the bottom of the tech pages is a comparison for coatings.
I use TiALN coatings for just about everything but Tin
works well for aluminum.

[nupeswv]

I personally do not use coated end mills/drills and such. In some cases they offer a bit of resistance to abrasive materials but as a good friend of mine informed me(who works as a tool manufacturer) they are generally supplied by low end tool manufacturers and the steel undernieth the coating is low grade compared to even medium grade hss tools. This may not make much difference to you until you work stainless steel or other tough materials. The bonus of hss tools are that they can be touched up, sharpened or reground and the material is just as good undernieth. (I sharpen my own end mills)

[vacpress]

thanks for the useful information guys..

so, i have ascertainedthat these coatings seem to be aimed at machine centers or materials beyond what i am doing. these bits will only be used to cut aluminum - ive got plenty of 4 flute end mills for other work.

my decision so far is this: Ballbose or steep angle HSS .125 2-flute endmill for doing all the pilot hole drilling, and a 2-flute HSS 1/4" flat bottom center cutting end mill to cut out the parts.

I am now setting up paths in mastercam, which I have only ever used to do '3D surface machining', so trying to make things cut logically is a sort of interesting side project.. Hopefully the code I generate will be ok on this AXYZ machine ive got access to..

Currrently thinking the hole drilling needs to be done at a a moderate speed, say 3o to 50 IPM.. I gather I should be calculating the rate based on bit diameter, material, and other factors, but my experience dosent lean this way.

For the countour routing and pocketing, I am thinking .075 to .1 depth of cut, at around 100 IPM. The machine can run at upto 300IPM, but it uses steppers and rack\pinion, and I think it is propbably happiest at about half that speed.

I hope to nest my parts, have the cnc drill pilot holes first, and then screw all the parts to a sacrificial board, and then have the 1/4" endmill cut them all out.. the small parts are going to have 'sprues' or other connections between them and the larger work piece which will be afixed to the milling table..

There is an image of the prliminary parts-nest at the end of the thread linked in the first message of this thread.

cutting fluids? i have been told 'you can use WD40 or some other light spray lube'.. i was going to just bring in a can of WD40.

Thanks,

Robert