new to enclosed tracks

They are not the same. A carbide ball end cutter will typically have 2 or 4 cutting edges, which provides more space around the bit to clear chips, as well as more flexibility for the manufacturer to grind the cutting edges with different geometries to suit different materials.

A burr will have many more cutting edges, which are much smaller. They are generally designed to be used in hand held grinders for finishing operations, but lots of people use them to cut tracks. Just be aware that they cannot remove material as quickly as a ball cutter and the fine edges can get plugged up with material which will cause everything to get hot. So you may need to feed slower, and remove as much material before the final cut as possible.

The first one is a spherical end mill, and the second picture of various burrs.

Quote from 808natural

So it can be successfully done with a ball bur. Will it cut through uhmw?

I've never tried it. If I had to guess, I would say that it will not work especially well on UHMW because each tooth can't take a big enough "bite" to cut cleanly. Burrs are often called "rotary files" and they work in much the same way. Since UHMW doesn't file well, my first uneducated guess would be that a burr might work, but leave an ugly cut.

But like I said, I haven't tried it.

Quote from 808natural

Is "spherical end mill" the correct name. Because no one seems to know what I'm talking about when I ask for a carbide ball cutter.

A "ball end mill" usually means an endmill that is ground square on the sides, and with the tip radiused to cut the bottom half of a round slot, like a core box router bit. But it won't cut an enclosed track.

A "spherical end mill" like the one I pictured, has a neck that is smaller than the diameter of the ball tip, so it can cut an enclosed profile. They aren't common (compared to "ball end mills"), so it wouldn't surprise me if some places didn't know what you meant.

Good luck. If you plan to use a router, you probably have collets that will accept either 1/4" or 1/2" shank bits. End mills are different. The shanks typically step up in increments of 1/16". So if you go looking for a 3/8" diameter spherical end mill, it will likely have a 3/8" shank, so that they don't waste time grinding down either the ball or shank from unnecessarily large stock.

That is why the custom cutters that I buy from SFS Carbide are nice. I have them all made with a 1/2" diamter shank, so they can be used with either a milling machine or a standard router. The 2-fluted ones in particular will cut as cleanly as anything that I have tried through UHMW. But they cost about $60 each for a minimum of 2.

The website is www.sfscarbide.com Call Bob White, and tell him what size you need. I usually get them in a little over a week.

By the way, if you refer to "Jeff's specs" they will know exactly what you are talking about and what you want with respect to neck size, rake angle, neck to cutter angle, etc.

about to start cutting my enclosed epoxy track. I got the neptonics ball cutter and just wondering if anyone knows what a good speed for cutting this thing on and end mill. I can only move the mill table slowly so feed rate cant really be changed. any advice or experience would be appriciated. I will try to post some pics of the gun when finished. its going to be a 60" rear handle tigerwood enclosed track freeshaft/lineshaft gun.

I would also highly recommend tigerwood and it seem easy to work with, similar to teak. Buoyance is nearly perfect and also water resistant. Not to mention the Beauty.

What is everyone's view on adding graphite to poured tracks? over kill, or necessary?

I dont think it is "necessary" but it I think it helps. I had a ton of it from my pine wood derby days and its pretty easy to find online. I also like how the black track looks but there are other ways to change the color.

Quote from Wishihadgills

I dont think it is "necessary" but it I think it helps. I had a ton of it from my pine wood derby days and its pretty easy to find online. I also like how the black track looks but there are other ways to change the color.

I was thinking of using some pigment to color the track but the graphite will make it black.

Quote from japsw

I was thinking of using some pigment to color the track but the graphite will make it black.

Here is some gray graphite sections in my old gun Tiputa, they are .020 above the rest of the poured track and have been holding up well since 1984.

Cheers, Don