[How do I?] B&S Surface Grinder Stepper Motor Power Table Feed

Pevehouse said:
Wow, so glad I ran across this. I am in the process of restoring a Harig 618 and would love to add a lot of the things you are talking about with your grinder. I hope you keep posting up your progress. I too have a challenger deluxe but looking at selling that one. At least that’s the plan at the moment. It’s complete but is going to require restoring for it’s been sitting up for about a decade or two. Thanks again for posting and I look forward to seeing the rest of your journey
Click to expand...
I will keep posting updates on my progress until I'm done and the grinder is up and running. I the rest of the electrical components I need to finish and I'll show how that all goes together when they arrive. Meanwhile a friend of mine has been working on a wiring diagram for me to follow.
 
Here is a video of the import surface grinder that I am using now. I added a table feed powered by a DC gearmotor and a bell-crank arrangement for the table movement. This setup works good at lower speeds and shorter table travel. Higher travel speeds and longer travel causes some jerkiness at the ends of the crank stroke. I hope the new surface grinder will run smoother with higher feeds and travel by using the stepper motor and timing belt to move the table.
 
bcap55 said:
snip> I will be running the 3 Phase output of the VFD to the original surface grinder spindle motor switch. <snip
Click to expand...

I believe you do not want to do this. The VFD 3 Phase output is to be connected directly to the motor. The original grinder spindle motor switch can be used, but either connected per the VFD control scheme or to control the 24V contactor you have mentioned.
 
BTW, my mill power feed uses pretty much the identical stepper brain and driver
Very happy with it!
dbf5f77d87d5083b7a99a63347aefc16.jpg


Sent from my SM-S911U using Tapatalk
 
Controls... I have it wired to stop at the ends. The black switch is a spring centered toggle. Push it the way you want the table to go.
256eb9321ffd53e8f0d714f5a6e2e13f.jpg
9217a554987c95ae34305ffe64a0c842.jpg


Sent from my SM-S911U using Tapatalk
 
extropic said:
I believe you do not want to do this. The VFD 3 Phase output is to be connected directly to the motor. The original grinder spindle motor switch can be used, but either connected per the VFD control scheme or to control the 24V contactor you have mentioned.
Click to expand...
Can you explain why the VFD 3 Phase output shouldn't be run to the original motor switch. I really planned on being able to turn the spindle motor on using this switch, it is at an easy to reach spot on the grinder.
Here is how I connected 3 Phase power from my rotary converter when I gave the grinder a test run.
The power goes to this fused cut off switch and then to the rotary motor switch. I think the switch handles all three legs of the 3 Phase.
IMG_4072.jpgIMG_4071.jpg
 
I'm not a VFD expert by any means and I'm confident that one of our more experienced and knowledgeable sparkies will chime in soon.
However, I believe my comment is VFD 101 basic knowledge.
The difference is that an RPC doesn't care if it has a load or not. It will idle without a care. An RPC will accept multiple motors being randomly stopped and/or started (within the capacity of the RPC).
On the other hand, a VFD will not be happy if it is instructed to output 3 phase into an open circuit (no load) or if the load on the 3 phase output is increased or decreased (I don't know the tolerance). Unless there are new protections that I'm not aware of, disconnecting the motor from the operating VFD will release the magic smoke.

I don't see why you couldn't use the existing rotary switch to control the contactor you described and that can control the VFD ON/Off, but the VFD 3 Phase output must be wired directly one (and only one) load.
 
extropic said:
I'm not a VFD expert by any means and I'm confident that one of our more experienced and knowledgeable sparkies will chime in soon.
However, I believe my comment is VFD 101 basic knowledge.
The difference is that an RPC doesn't care if it has a load or not. It will idle without a care. An RPC will accept multiple motors being randomly stopped and/or started (within the capacity of the RPC).
On the other hand, a VFD will not be happy if it is instructed to output 3 phase into an open circuit (no load) or if the load on the 3 phase output is increased or decreased (I don't know the tolerance). Unless there are new protections that I'm not aware of, disconnecting the motor from the operating VFD will release the magic smoke.

I don't see why you couldn't use the existing rotary switch to control the contactor you described and that can control the VFD ON/Off, but the VFD 3 Phase output must be wired directly one (and only one) load.
Click to expand...
Ok thanks, I don't have any experience using a VFD so I'll talk to my friend who is helping me with the wiring about this. It seams to make sense to not have the VFD constantly suppling power even though it's not needed.
 
bcap55 said:
Ok thanks, I don't have any experience using a VFD so I'll talk to my friend who is helping me with the wiring about this. It seams to make sense to not have the VFD constantly suppling power even though it's not needed.
Click to expand...
Good idea. Talk to somebody.
 
Yeah, +1 on this issue. 99% of VFDs do not want a switch between the VFD and the motor. If you do it you REALLY need to be sure the switch closes before the VFD starts!

I must mention that I am "that guy" who DOES have a high speed/low speed switch between the vfd and motor... with a very carefully installed "Go" contact set well after the drum makes up...

Just use the existing switch for the start/stop input on the VFD!

Sent from my SM-S911U using Tapatalk
 
You must log in or register to reply here.
Back
Top