Using R8 Collects/Spindle without a Key Slot

[JHCHOPPERS]

Has anyone used a BP Mill(or similar Mill) that has had the R8 Key Grounded out of the spindle?

I was talking with a retired Aerospace Machinist this morning, he said they used to grind off the Key inside the Spindles so it was easier to change R8 tooling. I said, "does the tool slip?", he said "No, you only need the key when changing the tool to keep it from moving when tightening the Spindle Nut or when you hog out something with a large cutter"

I was thinking if this was true, you might be able to make a R8 Tool Changer if you grind out the R8 Spindle Key ? Thoughts ?

[SCouch]

I know the old boy is right. We never replace the keys when they shear out because it's a pain in the butt. We never have trouble with tools slipping unless, like he says, it's a large tool like a 6" slotting cutter. In that event, a Bridgeport isn't really a big enough mill for a cutter that size, anyway.

[DreamFlyer]

On my mill a clone BP the key is actually an allen grub screw thru the spindle shaft easilt accessable. Take it out and see if you like the way it works.
Bob

[Geof]

I used a couple of R8 spindle machines for years without any key in the spindle. Your source of information is correct the key stops the collet turning while you tighten the bolt it does nothing to held the drive.

Is it your idea to replace the drawbar with some sort of pull stud in the thread in the collet and then make some kind of gripper that is down in side the spindle like on 40 and 50 taper machines? The problem you may run into here is that the R8 spindles are small in diameter and you may not have the space to do this.

[JHCHOPPERS]

Originally Posted by Geof I used a couple of R8 spindle machines for years without any key in the spindle. Your source of information is correct the key stops the collet turning while you tighten the bolt it does nothing to held the drive. Is it your idea to replace the drawbar with some sort of pull stud in the thread in the collet and then make some kind of gripper that is down in side the spindle like on 40 and 50 taper machines? The problem you may run into here is that the R8 spindles are small in diameter and you may not have the space to do this.

I was thinking of using the stock BP R8 drawbar but with a Pneumatic Power Drawbar attachment. With the key gone, then you would not have to worry about the alignment of the collect into the spindle. The Pneumatic Power Drawbar could be placed under computer control with Electronic Pneumatic Values.

The tools would be placed in a special rack, maybe in a 2 x 4 configuration, on the far side of the table with known XYZ locations for each tool. The rack would be mounted to the table and have a rubber seat for each tool to keep the collect snug in the drawbar during load/unload operations. Each tool holder on the rack would have a sensor to help ensure the tool was released and installed. I was also thinking of moving/motorizing the knee for tool changes only. Sense R8 Collects are so tall, the Quill would not have the reach to change the tools. Then after each tool change, automatically re-zero the Z of the tool on a tool touch off/zeroing pad, sense the knee was moved and the nature of R8 Collects.

Any/All feedback is welcome on this idea. This would chance my CNC BP into a VMC BP !

[Geof]

So the collet would be pushed up into the taper by the rubber seat so it does not turn while the drawbar screws out or in.

That sounds okay but when you are taking the collet out how to you go from pushing it in to pulling it out? You cannot push it out with the drawbar; well you can of course, you slacken the drawbar a few turns and then have some mechanism to push the collet out of the taper. But now the collet is free to turn so how do you unscrew the drawbar the rest of the way. If you push it back up with the rubber seat to grip on the taper once you have unscrewed the drawbar how do you then push it out again?

[JHCHOPPERS]

Good questions Geof. I think the in part will work, its getting the out to work reliably might be the trick. When I use the Power Drawbar now, the Collect almost always fails out into my hand, I can’t remember it not failing out. There might be enough vibration from the impact wrench that breaks it loose? I will have to pay more attention to it when I use it, at least for a while...

On my other machine, it’s a manual drawbar and I need to tap it with the dead blow hammer to pop out the Collect almost eveytime. Maybe we will get some more feedback on this in the next couple of days? Have you used a Power Drawbar?

[Geof]

I have never used a power drawbar but one of my R8 machines had the drawbar retained by a cap with a hole. As you continued to loosen the drawbar it pushed the collet out of the taper.

What you might consider for holding the collets is something with three blades that would fit in the slits. You would need to orient the spindle so that is an added complication.

[HelicopterJohn]

Here is something you might want to look at if you want a Quick Change R8 system.

http://www.mach-1tooling.com/tool18.asp

[tmaker]

I have replaced the grub screw once not hard to do. I have also been using a bp without one for about 4 years now, had a big cutter and the part moved. Have not had a problem as long as the draw bar is tight, a power draw bar impact attachment will work just fine for what you want to do, but they tend to over tighten and pull the threads on the draw bar if you don't turn the air pressure down. good luck hope it works for you.

[md63825]

In my 15+ years as a machinist, I don't recall running a BP that the key was left in. When using a manual drawbar, the collet is usually wedged into the spindle enough that the drawbar screws up and out of the collet and then requires a small peck on top of the drawbar to release the collet. And the power drawbars that I have used, usually have enough tension in the air powered mechanism atop the machine to force the collet out of the spindle when being removed. The wedging action of the collet being drawn into the spindle by either manual tightening of the drawbar or by a power drawbar tends to keep the collet from spinning. Its just a matter of personal preference I think. Removing the key won't cause any mechanical harm to the machine.

[toastydeath]

The key is this dinky small thing, and doesn't do squat to keep the tool from rotating. If you generate enough torque on the collet, so much so that it spins, that pin is going to shear straight away and dig in to the collet. Trying to get the collet out after that is no fun whatsoever.

Just take the darn thing out, and save yourself time and effort putting tools in the machine as well as recovering from crashes.