MT#2 opinions sought for Atlas Mill (application applies to general machining)

[Uncle Buck]

I intend to use a MT#2 shell mill holder and a shell mill fitted to the spindle of my little Atalas MFC milling machine. I already have both the shell mill holder and the shell mill. I will be removing the tang from the holder followed by drilling then tapping the holder for a drawbar. Given the size of the shell mill I suspect that it will be pushing the upper limits of the work the machine is capable of performing. To that end I intend to make my first test cuts on aluminum once I get this all set up before moving on to cut steel.

When these machines were new Atlas sold a shell mill holder and shell mill that was supposed to screw onto the end of the spindle so I know the machine was intended to perform at least some functions with a shell mill. However, the original Atlas setup was screwed to the spindle and not working off of a MT#2 holder. I think that was likely because an adapter screwed to the end of the spindle was better equipped to handle the strain a shell mill would put on the spindle and prevent a taper from spinning in the spindle while in use. Also I believe the original Atlas would have better handled the side load issues related to these cutters that are rather large for such a small machine.

Getting to the point of my question; I anticipate having to really apply a lot of torque to the drawbar so that I can seat the taper in the spindle as firmly as possible. My fear is that I will seat the taper too tightly into the spindle and not be able to break it free once I want to remove it to change tooling. I thought about applying a thin coat of oil to the taper in the hope that it might help prevent the taper from effectively welding itself to the spindle. I have never oiled a taper prior to mounting it in any application I have ever done such as this. On the flip side I fear that oiling the taper will really do nothing but assure that the taper will spin in the spindle once a real load is applied to make a cut.

So does anyone here have any experience with this and have any wisdom or thoughts that might help me along as I make my way through this exercise? I would greatly appreciate anything others might be able to share or suggest. Thank you folks.

 

[Tony Wells]

Since most oils are designed to form a film not easily displaced from the two parts oiled, and provide a lubricated bearing surface and actually prevent the actual surfaces touching, I'd tend to think it contrary to the purpose of a locking taper. I've never actually put oil on any taper that I wanted to stay seated, but I suppose the theory could be that unless there were some lube, you could gall it should it spin. But the whole idea of a locking taper is to not spin. I don't believe I'd oil it beyond what was on my hands. For a firm lock, tapers need to be metal to metal.

 

[Uncle Buck]

Since most oils are designed to form a film not easily displaced from the two parts oiled, and provide a lubricated bearing surface and actually prevent the actual surfaces touching, I'd tend to think it contrary to the purpose of a locking taper. I've never actually put oil on any taper that I wanted to stay seated, but I suppose the theory could be that unless there were some lube, you could gall it should it spin. But the whole idea of a locking taper is to not spin. I don't believe I'd oil it beyond what was on my hands. For a firm lock, tapers need to be metal to metal.

Your answer confirms my thoughts exactly, well put. I guess I will just have to cross my fingers and hope everthing works as I am intending it too. I think the increased size of the cutter might have me a bit spooked. I think I will just move forward slowly and conservatively as best I can and sneak up on using the shell mill when the time comes. Hopefully by starting out taking only very modest cuts I will be able to get a better feel for how this is going to work for me. Thank you Tony!

 

[kd4gij]

Will you be using them horizontle or vertical?

 

[Uncle Buck]

Will you be using them horizontle or vertical?

Planning horizontal use as the machine was originally configured. I don't think there is enough ridgidity in the machine to use it vertical even though I do have a home grown vertical head. I think before I would ever think of attempting that I would equip my machine with an outboard overarm support. The outboard arm addition is part of my future plans for the machine anyway as I see there would be some clear benefits to such an addition.

As I said earlier, when sold new, Atlas offered an accessory shell holder and cutter but the original version screwed to the end of the spindle instead of employing a #2 MT which I suspect was done for some good reasons.

 

[Bill C.]

I intend to use a MT#2 shell mill holder and a shell mill fitted to the spindle of my little Atalas MFC milling machine. I already have both the shell mill holder and the shell mill. I will be removing the tang from the holder followed by drilling then tapping the holder for a drawbar. Given the size of the shell mill I suspect that it will be pushing the upper limits of the work the machine is capable of performing. To that end I intend to make my first test cuts on aluminum once I get this all set up before moving on to cut steel.

When these machines were new Atlas sold a shell mill holder and shell mill that was supposed to screw onto the end of the spindle so I know the machine was intended to perform at least some functions with a shell mill. However, the original Atlas setup was screwed to the spindle and not working off of a MT#2 holder. I think that was likely because an adapter screwed to the end of the spindle was better equipped to handle the strain a shell mill would put on the spindle and prevent a taper from spinning in the spindle while in use. Also I believe the original Atlas would have better handled the side load issues related to these cutters that are rather large for such a small machine.

Getting to the point of my question; I anticipate having to really apply a lot of torque to the drawbar so that I can seat the taper in the spindle as firmly as possible. My fear is that I will seat the taper too tightly into the spindle and not be able to break it free once I want to remove it to change tooling. I thought about applying a thin coat of oil to the taper in the hope that it might help prevent the taper from effectively welding itself to the spindle. I have never oiled a taper prior to mounting it in any application I have ever done such as this. On the flip side I fear that oiling the taper will really do nothing but assure that the taper will spin in the spindle once a real load is applied to make a cut.

So does anyone here have any experience with this and have any wisdom or thoughts that might help me along as I make my way through this exercise? I would greatly appreciate anything others might be able to share or suggest. Thank you folks.

What I did was to loosen the drawbar a turn or two then tap it with a hammer on the end to knock if forward or down to remove the holders. I nevered oiled them before using.

 

[Uncle Buck]

What I did was to loosen the drawbar a turn or two then tap it with a hammer on the end to knock if forward or down to remove the holders. I nevered oiled them before using.

Agreed, that is all I have ever done as well. I was just a bit concerned that I might have issues swinging a shell mill that is most of 2" diameter x 1.5-2.0 inches wide. For the little Atlas that is a fairly hefty cutter and I feared that I might have issues running it off of the MT#2 taper in the spindle instead of running the shell mill from a holder that screwed onto the spindle as the original Atlas versions did. I am likely over thinking the whole thing and I will hopefully have no issues at all.

So far the largest end mill I have used in this machine has been maybe a 1/2" or 3/4" end mill off of my vertical attachment. Thus I have no real history with knowing just how stout this little mill is going to be with larger sized cutters.

 

[kd4gij]

I would make a coller for the arbor to ingage the pins and have it tig welded on.

 

[Syaminab]

Just put thin paper in between, paper + metal grabs really well, and pushes out easily. Dont oil the paper.

 

[pineyfolks]

I run a 3" homemade flycutter in my Rotex with no problem. Your facemill should do fine with moderate cuts and feed especially if your cutter has some lead angle. My mill is a #9 B&S taper so it's close to a #3MT in size even though it's larger than your's I see no problem.