cnc general questions

[helodude1]

I am a new owner of a cnc supra mill. I am also new to machining, and I have a couple of questions in order to get started.
1.) what is a good coolant for someone who is going to be cutting mostly aluminum, will not be using the machine very much once a month(does this tend to promote rancidity?)What is rancidity?
2.) I got a 4th axis and was wondering how you attach parts to it. What is a tail stock? Do I need a chuck or they only for round stock? Will they open wide enough to hold a part about 6" square for example?
thanks in advance

[ImanCarrot]

Rancid coolant is caused by bacteria that multiply when there's no air in the coolant and it can stink and cause dermatitis. A small fish tank type air pump slows them down. Synthetic coolant seems to be less prone, but others will have to confirm actual type.

The 4th axis is basicaly a CNC controlled rotary table- it should have T-slots to bolt things on to.

A tailstock is used on a lathe (you have a mill!) to essentialy hold the end of bars that you want to machine- without it bars or rods tend to wobble so much that they fly out of the chuck (usualy at head height). If the chuck is on the left, the tailstock would be on the right, past the toolpost. You usualy drill a small v shaped hole in the end of the bar with a centre drill then put a live (or dead) centre in the tailstock and push it into the v hole to hold the end of the rod.

I use a 3 jaw chuck on the mill to hold circular parts (I clamp the chuck to the mill bed)- it's handy if you're doing lots of the same part. For a square part you'd need a 4 jaw chuck, but youd usualy use a vise.

I'm not an expert though! so please feel free to add or ammend anyone!

Before you go buy cutting tools, most folk recommend HSS, two fluted end mills for ally. Carbide doesn't like thermal shock from the coolant and can chip.

[HimyKabibble]

Originally Posted by helodude1 I am a new owner of a cnc supra mill. I am also new to machining, and I have a couple of questions in order to get started. 1.) what is a good coolant for someone who is going to be cutting mostly aluminum, will not be using the machine very much once a month(does this tend to promote rancidity?)What is rancidity? 2.) I got a 4th axis and was wondering how you attach parts to it. What is a tail stock? Do I need a chuck or they only for round stock? Will they open wide enough to hold a part about 6" square for example? thanks in advance

1) Do yourself a favor, and get a decent mist coolant sprayer. Flood is not necessary for a mill in the BP class, and will create a lot of problems, especially in occasional use. The FogBuster is an excellent system, and will provide all the cooling a knee mill requires, even for the heaviest cuts.

Regards,
Ray L.

[9 1/2]

Tail stock can be used on a 4th in the same manner it is used on a lathe. To support long stock. Usually a 3 to one ratio. IE: 1in dia = 3" max stick out before a tail stock would be use. One caveate: this rule applies only in an optimal situation and must be adjusted for less than optimal set ups, DOC and or type of operation being performed.
Square stock must be held in an four jaw though creative fixturing would allow holding in a three jaw universal chuck.
Do yourself a favour and get some training. Cutting speeds, DOC, and basic metalurgy will make you a safer hobby machinist and allow for proper tool life.

peace