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 ?

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.

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

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 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 !

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?

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?

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.

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

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

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.

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.

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.

I think what's being suggested here is a great idea.

Here's my 20 mils;

1. Take the collet key/pin out for sure.

2. Make the draw bar captive so when it spins to loosen, it pushes the tool holder of the spindle taper.

3. Put a standardized size ring around the tool holders. This ring has a notch/teeth/pin/spline that can easily line up with the tool holder sockets that hold the unused tools. The un-spinning action should allow the alignment of ring and socket.

4. The tool holder sockets may need to be spring loaded in Z-axis to take up screwing / unscrewing displacement. -or- see six below.

5. I can see R8 Drill chucks, R8 Morse taper, R8 endmill and shell holders but you really can't be talking about COLLETS can you? Once out of the spindle won't they drop the tool or at least slip?

6. It wouldn't take much to put a small air cylinder under the tool socket(s) to lift the tool up into and down out of the spindle. That might actually be easier than driving and controlling the knee in synchronism with tool change operations.

John

HI,
I've been using an R8 miller without a key for many years, I have had no problems, other than the drawbar wearing out, it and that could have been just normal wear and tear. Even when using large cutters I have never had one slip, perhaps I'm just heavy handed on the drawbar.
Cheers
Mick
;-)

yup as toasty says they can make a mess of your collets and a right pain
in the arse to get out when they do go tu
seen auto eject manual drawbar attachments,basicaly just a left hand thread
on the drawbar and a l/h tread collar on the spindle as you slacken it pushes the collet out

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


Yes the allen screw is easy to remove if it has been ground down, but try removing it when the key has been smeared around the inside of the spindle because some operator crashed the machine hard and you'll know why people remove them. (spent 7 hours drilling out screw and messing around with tiny chisels getting that thing out)

I think what's being suggested here is a great idea.

Here's my 20 mils;

1. Take the collet key/pin out for sure.

2. Make the draw bar captive so when it spins to loosen, it pushes the tool holder of the spindle taper.

3. Put a standardized size ring around the tool holders. This ring has a notch/teeth/pin/spline that can easily line up with the tool holder sockets that hold the unused tools. The un-spinning action should allow the alignment of ring and socket.

4. The tool holder sockets may need to be spring loaded in Z-axis to take up screwing / unscrewing displacement. -or- see six below.

5. I can see R8 Drill chucks, R8 Morse taper, R8 endmill and shell holders but you really can't be talking about COLLETS can you? Once out of the spindle won't they drop the tool or at least slip?

6. It wouldn't take much to put a small air cylinder under the tool socket(s) to lift the tool up into and down out of the spindle. That might actually be easier than driving and controlling the knee in synchronism with tool change operations.

John


Check out the mach one tooling system for R-8, they change out the drawbar with a spring loaded pullbar mechanism and you can use either the more traditional spring collet or a collet chuck (or face mill holder, or endmill holder, jacobs chuck etc.). I've used the system briefly once and it worked great.

5. I can see R8 Drill chucks, R8 Morse taper, R8 endmill and shell holders but you really can't be talking about COLLETS can you? Once out of the spindle won't they drop the tool or at least slip?

John

Thanks for all the feedback!

I think I might try to impliment this as time permits. If I do, I will post it here one the ZONE. Yes, I plan on using Shell Holders, not Collects (my bad).

i can almost guarantee you that if u leave the setscrews in the quill that in time you will see the slot of ur R8 tooling get eaten up. that little dog on the end of the 1st set screw doesn't have enough of a load bearing surface and that it is harder than the collet it will be the collet that gives up the ship. so do urself a favor and get rid of it. if left in it may even cause a slight jam of the collet if it turns. then u'll have to smack the draw bar to get it out.

good luck