# Thread: Cant machine Ally :(

1. ## Cant machine Ally :(

Hi all im trying to machine thin ally eg 1 - 2mm thick but my HSS end mills just keep getting black to hot i use coolant.

I think the problem is im using a wood router and even the slowest speed is to fast and tbh im scared on speeding the feed up instead or is this really the only way other than to purchase a Chinese spindle tho that's what I actually want just got no money for that .

Any advice would be great cheers all

2. Well I think I can help maybe.
So if the slowest speed on your wood router is 12000 rpm
The max speed is 20000 rpm.

cutting speed X 4
----------------- = RPM
Diameter

The numbers are from my text book there may be slight deviations.
Cutting Speed of a HSS end mill in alurminum is 200.
Cutting Speed of a Carbide end mill in aluminum with about cut depth of 0.015 is 800.

So using a hss the diameter of your cutter would have to be 5/64 HSS end mill running at your lowest speed setting.
If you got yourself a carbide end mill of 1/4" at the lowest speed setting the cutting speed formula works out.
So your problem most likely is spinning the cutter too fast. Your easist solution is to get a proper sized end mill for the rpms of your router.
You can also rearrange the forumula as

CSX4/rpm = diameter to figure out a good diamter.
watch your depth of cut as well.
Jon

3. holy crap thanks for the reply but I have just got lost hahahahahahhaa.

Ok im off to read it again im a very slow learner on some things and this is one of them.

You help is very welcome tho cheers.

P.S I do own a 6mm carbide end mill and you are right it works much better than the HSS end mills.

The formula you have show me is im sure very easy for others to understand but im very bad at this kind of thing hehe.

All so are your workings out for RPM or for what feed rate I should be running?.

im all so limited on the O.D of cutter I can use I think my max collet for me router is 8 or 10mm.

Cheers

4. diameter is in inchs not metric
6mm = 0.236inchs which is so close to 1/4inch that i think it would work. how fast does your router spin out of curiousity?

5. Im not sure im sorry I would have to look tomorrow but I dont even think it says on the router itself.

I will need to look at model I suppose then do it that way.

edit ok I will sneak out into workshop brb :P

6. ok its this one http://www.comparestoreprices.co.uk/...-fmtc1020r.asp

min rpm is 11500 rpm
max rpm is 34000 rpm

max collet is 1/4".

edit

hahaha the price of it on that site :O its a cheapy not sure why its that much hehehe :P

7. Just keep speeding your feed rate up till you find the sweet spot. On my machine with a 1/4th 2 flute HSS EM @ 8k rpms and a .0700 depth, a feed rate of 50ipm worked well. I didn't use any coolant.

The best thing you could do is get an o-flute endmill. Since they only have one cutting edge you get the proper chip size to take the heat away from the cutter. Bigger chips means less heat. Also, you're not using a down spiral are you? I've ruined more than a few end-mills but the only ones that turned black were down spirals. I've melted aluminum on some HSS endmills before but it didn't turn black.

8. Hi thanks every one for the reply's.

Im sorry a down spiral how do I tell?.

I all so have some 2mm end mills i would like to use but I cant is that correct because the slowest speed will still destroy the end mill?.

cheers all

http://www.woodcraft.com/Articles/Ar...?articleid=445

It's a balancing act between how fast your router is and how fast your machine can move to cut it to get the right size chip per cut. Some people take very shallow cuts at 125ipm at the lowest speed their router will turn at.

You can cut aluminum with a router but you have to be able to up your feed rate to get the right cut size. When the metal chips are cut and fly away, they take heat with them. The larger the chip size, the more heat it takes. So you need to up your machine speeds to get the right chip size that'll keep the router bit cool.

If your machine will not move fast enough, then you should probably look into getting a single O-flute endmill. Since it only has one cutting edge it'll take bigger cuts and keep the endmill cool.

10. Ok all thank you very much for the help I will have a play an see if I can get the right feed rate to enable a nice cut into ally.

P.S

If I want to machine thin steel eg a computer side panel would I be ok with the bits I have I just have to get the feed right?.

11. Originally Posted by stk2008
Ok all thank you very much for the help I will have a play an see if I can get the right feed rate to enable a nice cut into ally.

P.S

If I want to machine thin steel eg a computer side panel would I be ok with the bits I have I just have to get the feed right?.
Maybe....you'd have to specify the tool for an accurate answer.

Machining stty is such fun.

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