Need Help!- Newbie! What spindle to buy for milling??

[Maxreebo]

Hey guys, im new to the world of cnc. We recently bought a second hand homemade machine, and have spent some time getting to grips with its operation and all the software.

We are using the cheap MKeller router that came with it, and have got it working fine with Mach 3

Now, we will be wanting to try alu and brass, but as far as I understand it for that we need to be running at between 1000 - 3000 rpm and using a milling bit rather than a routing bit.

Our router runs between 10'000 and 25'000 rpm.

Ive been looking around for something that replaces my router, but runs at milling speeds. I can really find the answer, other than a 240v drill of somekind.

Can someone link me to something like im after?? Im confused!

Thanks
Max

[DonFrambach]

You can buy a small spindle such as a Sherline or a Taig (goes by another name in UK). These spindles run at lower speeds and are designed to cut metal on their respective small mills.

You can also use the "Super-PID" to slow down your current router. http://www.vhipe.com/product-private/SuperPID.htm

However, unless your router is fairly rigid, it will be difficult to use it to cut metal. Several years ago, I put a Sherline spindle on an old ShopBot router with disappointing results.

[rowbare]

A lot depends on how fast your rapids are and the size of the bit that you use. When doing metal the two main considerations are surface speed, how fast the cutter is moving in relation to the metal it is cutting and chip load, how much material each tooth will remove. Surface speed is a function of rpm and cutter diameter and chip load is a function of feed and the number of teeth the cutter has.

If your chip load is too low, then you risk melting the material rather than cutting it. With the right chip load, the heat generated by the cutting operation will be in the chips not the cutter and workpiece. A good starting point for chip load is (EndMill Diameter)/200. Note that if cutting aluminum you want to use a two or three flute cutter. Four flute cutters tend to clog.

The take away from this is that by using a smaller cutters (1/8" range) with light depth of cuts, you can get away with using your current setup providing the runout on your spindle isn't too bad (at least in aluminum, brass is a bit iffy). If you spend a bit of quality time with a good feed and speed calculator, there are some online or check out GWizard, you can get a sense of what you can do.

A couple of affordable options for a light milling spindle are the Taig (Peatol in the UK) ER16 spindle (about US$120 part#200-60 Taig Tools - Desktop Milling Machines and Lathes.) or the Sherline industrial spindle cartridges (spindles). Either of those will run up to about 10K with the appropriate motor.

As Don mentioned, whether or not this makes sense depends on how rigid your router is.

good luck!
bob

[Maxreebo]

Thanks for the replies guys. I think we are ging to go with a Kress router setup. the 1050 will go down to 5000 rpm and up to 25-30000 so we should have a good base providing we get out rates right

This is also pretty cheap too.

Thanks again for your help, it is much appreciated.

Max