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Rockwell drill press requires manual start

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Forum topic by Jackthump posted 07-08-2018 09:13 PM 727 views 0 times favorited 7 replies Add to Favorites Watch
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Jackthump

5 posts in 377 days


07-08-2018 09:13 PM

Topic tags/keywords: drill press troubleshoot delta vfd

I have a Rockwell Delta 17-600 drill press with a vfd. It was running smoothly and then it started to get a little loud. Now when I try to turn it on, it whirs but doesn’t move and I get an “oca” error on the vfd. I looked that up, indicating an over current error and perhaps the torque settings weren’t right. Nothing on the vfd seemed to fix, but if I hit the on button and then manually twist the spindle with my hand, the machine will run.
I’ve tried disconnecting the pulley belt and running just the motor, and that seems to start and stop with no issues. Any thoughts? Is the vfd detecting too much torque required so it’s shutting off? Is this a bearing issue?


7 replies so far

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Kazooman

1325 posts in 2372 days


#1 posted 07-08-2018 09:39 PM

When you had the belt off did you spin the other components to see if they were moving smoothly. My guess is that they are not. I do not have a vfd, but if I take the belt off the pulley on the spindle of my Delta drill press and give the chuck a spin it rotates smoothly and will turn several revolutions before coming to a stop. If your spindle doesn’t turn freely it could be a bad bearing or something else causing the spindle to bind in the quill. Should be easy to isolate the problem and make the repair (famous last words).

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Jackthump

5 posts in 377 days


#2 posted 07-09-2018 12:04 AM

It certainly doesn’t spin on its own when I try rotating without the belt on. I will look into that further.

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Kazooman

1325 posts in 2372 days


#3 posted 07-09-2018 12:09 AM



It certainly doesn t spin on its own when I try rotating without the belt on. I will look into that further.

- Jackthump

One more step down the investigative journey. Vfd – probably OK. Motor, probably OK. Something is amiss in the
spindle. Bearings? Build up of crud? You are well on your way to locating the problem. Keep us posted!

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Jackthump

5 posts in 377 days


#4 posted 07-16-2018 04:35 PM

I’ve taken apart the top section of the spindle. There are two bearings, one of which seems a little sluggish. When I try and spin it with my thumb, it might go one rotation before coming to a stop. The lower part of the spindle is a little more complicated. There’s a bearing closure nut that’s going to be difficult to get off. The parts diagram doesn’t actually call out a bearing there….just the closure nut. I’m not sure if that’s worth the effort to take apart. I’ll try putting on a new bearing that I bought on ebay (delta doesn’t make it anymore) and put it back together. I’m certainly learning a lot more about my drill press than I ever thought I would. Anyone have any experience with these closure nuts? Is this worth taking apart?

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Jackthump

5 posts in 377 days


#5 posted 07-19-2018 01:15 PM

Update. I’ve gotten the lower spindle section apart. There was a series of four youtube videos on an old delta drill press that was helpful. I’ve order new bearings, though the old ones don’t seem bad. There are four total, two in the lower spindle and two in the upper. I’ve replaced one of the upper ones. The second upper bearing seemed really smooth and there was a key in the way that I couldn’t get out…didn’t seem worth it. On the lower section, the two bearing are shielded on one side and sealed on the other. I can’t find any bearings like them. I’ve bought a pair of shielded bearings and a pair of sealed bearings (since they were cheap). Any suggestions? Given that the original issue seemed to be that the drill press needed “help” to get started, I’m leaning toward using the shielded bearings because I assume they’ll have less friction.

After all this, I wouldn’t be shocked if all I needed in the first place was just a new belt or something stupid like that :/

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Mike997

3 posts in 368 days


#6 posted 07-20-2018 03:02 AM

The overcurrent error is several seconds after it tries to start, right? The vfd isnt able to produce enough torque to start, so the motor draws locked rotor current and eventually trips the protective device. It should be able to produce pretty high torque at starting, and if you can move the thing with your hand, the vfd should normally be able to exceed that. If you eliminated the mechanical causes, nothing seems to be sticking or jamming it up, then it could be that the vfd isnt firing correctly. The VFD is a rectifier, DC bus, then an inverter back to AC. If one of the thyristors/IGBTs isnt turning on when it’s supposed to, you would get significantly reduced torque. If you could see what the voltage looked like to the motor, it would tell you if it’s an electrical or mechanical problem.

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Jackthump

5 posts in 377 days


#7 posted 07-23-2018 02:42 PM

Argh….

I was thinking the same thing, albeit two weeks too late. The VFD error troubleshooting pointed to insufficient torque…but that bearings didn’t seem that bad. Perhaps before I took the whole spindle assembly apart and bought bearing removers and new bearings…..I should have looked closely at the VFD. I went to check the current in the wires only to find that one of the wires slipped out of the end connector and was disconnected from the VFD. I could have fixed that in 30 seconds had I just looked there first.

At least I learned a lot about how my drill press works :/ Thanks for your help!

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