Bridgeport spindle brake - how fast should it stop?

[swarf_rat]

I put a new air cylinder on the Series 1 rigid ram ($22 from MSC) but in doing so disturbed the adjustment, such as it is. With the old cylinder, the spindle would stop so fast you thought it might break something. Basically instant. With this one adjusted as it is, it stops in about 1-2 seconds. What is normal?

The only adjustment seems to be the trunnion on the end of the cylinder (fine), and the splines on the arm (coarse). The brake shoes are the same ones, looked good when I put them back in.

[gus]

if you slow it down, it may wear the shoes eventually. My r2c3 stops pretty instant and I have owned it for 15 years without touching it

[Dennis Storzek]

Are you sure the new cylinder has exactly the same stroke as the old one? Is the rod extension the same length? My Series I Boss stops so fast we were originally concerned it would unlock the Quik-change collar, although it never has. Try loosening the bracket and pulling the brake down by hand. If you get the same results as you got with the original cylinder, the new cylinder doesn't have quite enough stroke, and you'll either have to readjust the linkage or move the cylinder mounting bracket.

[swarf_rat]

The new cylinder seems to be an exact replacement for the old. Different name on it, but I would be surprised if they came from a different assembly line. However, I had to make a new bracket, since the original (?) was made such that would not allow it to line up properly. When I got the machine it had one bolt missing, because if it was there the thing could not be assembled. Looked like it had been run that way forever, but surely the factory would not have let it leave that way?

Anyway, there is adjustment when you swap, depending on how far you screw the trunnion on the cylinder. I didn't think to measure this before I removed the trunnion from the old cylinder (which required destroying the old cylinder). But it is easy enough to adjust. If normal is that it stops instantly, then I will adjust to normal! In many ways that was nice, didn't have to wait long to change the tool. It just seemed kind of violent.

[Dennis Storzek]

I just had to pull a Series I Boss vari-speed apart, and I noted with interest that there is a whole section in the manual on converting the machine to air driven brake and speed control. It looks like one or both were options, and many may have been field installed. The manual is nice enough to point out that if you are drilling the holes for one, you should do both at the same time, so it looks like a field installation required the installer to lay out, drill, and tap the holes; never a safe bet.

Someone may take exception with this, but I normally leave the brake turned of and let the spindle coast to a stop, then activate the brake to lock the spindle while loosening the Quck change and/or collet nuts. I've never read anything one way or the other, but we had a guy working here for a while that was scared silly that the momentum of the Quick change collar would unlock it during the fast spindle stop, and having once watched spindle threads appear behind a big faceplate on a wood lathe when I was in high school, I can't say that couldn't happen, but it never has anytime the brake switch was forgotten and left on.

Dennis

[swarf_rat]

It is interesting that a field install was described. I think it was standard from the factory on the Interact, but that might explain why the bracket appears to have been misaligned.

I leave the brake in the off position most of the time as well. But I am in the habit of hitting the E-stop button frequently, to turn the servo drives off and quiet them so I can think. When you do that, the brake actuates regardless of the brake switch setting. This is one safety feature I am reluctant to defeat, since there are occasions when I would like the E-stop to stop! There seems to be no other way to tell the control to de-power the servo drives.

The pneumatics originally prevented using the power drawbar unless there was pressure on the brake cylinder, I could think of no reason for that so I fixed it.....