Grounding router spindle?

[Mogal]

Hello all!!

I am looking for some info on how to ground my Bosch Colt router spindle.
I use Mach3, and Gerry's awesome 2010 Screenset.
I have a tool setter, which works great, although, I have to attach a grounded
alligator clip to the bit before I set the tools.

I have a couple relays on the way, and would like to wire these up to control
the router and vacuum. The problem is the clip, and grounding the tool.

So my question is, how can I ground the tool/spindle to avoid the alligator clip?
and allow for automatic operation of the spindle after the tool change.

Thanks!

Machine as pictured:


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[ger21]

I think that your only option is to take the Colt apart and run a ground wire to one of the spindle bearings. Since the housing is plastic, you can probably grind a recess on the side of the bearing housing so that when you press the bearing back in, it holds the wire in place.
Be aware that if the Colt has a short, this can be dangerous as you'll be able to get a shock from the spindle.

[Mogal]

Hi Gerry,

I just took the router apart, seems like the bearings themselves are isolated from the shaft too!
(No continuity between the outer race and shaft) I'll need to make contact with the rotating shaft.

I just bought a bunch of replacement carbon brushes, maybe I can devise something on the head of the router...?
looks there is a good 1/4" or more space there...

[Mogal]

Here is a prototype I'm going to try for grounding the spindle.
Not sure of the longevity this will have, but I got about 5 years
off the original brushes, maybe I'll get the same for the grounding?

From the pics you can see what I've done here... I took a small piece of Teflon,
drilled a 1/4" hole in the middle(But not quite through)Then drilled a hole just
big enough for the wire to pass through... I used the little cap off one of the brushes,
and soldered my red wire to it, and fed it into the Teflon sleeve.
I then slid the modded carbon brush into the top of the router, and into the sleeve.
Slid everything together, and tested for continuity. and Wahlah! a grounded spindle!

Dimensions of the sleeve:
Length: 0.375"
OD: 0.5"
ID: 0.25"
ID: 0.125"

Everything seems to be working great... I'll post a follow-up if anything goes wrong!
Trying to put everything together was a little tricky, but worked out.

Cheers
Chris

[Mogal]

Update:

Preliminary tests are great! and this is working out awesome!!
I have a couple of hours run time now, with no issues.

As part of my flash-up routine, I'll test the continuity of the spindle.
I'll get a couple more hours on it, and check the grounding brush for wear.

A little more automation on the machine! Yeah!

[Mogal]

Well, time for another update.
After about 100hrs, the carbon brush failed.
I think the main problem was that I made it too small
and the spring slipped over the brush.

The idea is still feasible, so I'm going to continue playing with it.
I'm designing a holder for a full size brush to be placed in the same
location...

[GTFreeFlyer]

Hey Mogal. Here's what I did but it is also failing after running a bit. I'll try to come up with something else. Let me know when you solve the issue and I'll do the same.

http://www.cnczone.com/forums/momus_...s_probing.html

[Mogal]

Hello, I'm back at my design and testing phase again...
I tried the A super-simple tool height setter! by RomanLini but can not get accurate results with different sized bits

So I'm trying the carbon brush idea again...
This time I wont be modifying the brush and will be making a bigger holder for it.

I'll keep you posted!

[Mogal]

So here is my (new and improved!) 3D Printed Carbon Brush holder.
This time, it takes a full unmodified brush, so hopefully will last MUCH longer.

So all I've done, is made the holder and enlarged the hole in the lid to let this just pass through.
There is a spring that raps around the holder with the lid pushing down on it to keep it in place.
I also enlarged the hole in the top of the body to allow the brush to pass through and make contact with the spindle.

Sorry didn't take pictures this time around, but if need be, I'll take some for yea
I include my ViaCAD file and STL if you wish to print them yourself!

I'll keep a tab on my running hours again to see how long it lasts.

Cheers!
Chris

[Mogal]

Just wanted to post an update on the new setup here.
I now have over 100hrs on this brush, and there is so little wear showing and I get perfect zeroing every time.
Its working out GREAT!
Highly recommended to those of you who would like to ground out your tool without alligator clips!

[GTFreeFlyer]

How's it holding up during these past few months where you haven't posted? I pulled my setup out because it wasn't reliable.

What is the carbon brush? Is it just a solid carbon bar? It looks like it has serrations cut on the end? What are those for?

What did you do on the other end that sticks out of the cover? Did you just wrap exposed wire on it? Would love to see another photo if you have it.

Would also love to see a photo of the top of the spindle area (cover obviously removed). Did you have to modify this area at all?

[Mogal]

This new setup has been 100% reliable.
Not a single problem with the touch probe at all.
I have about 200 hours on it, and there really isn't any wear on the brush.
I'm super happy with this setup.

The brushes I got off ebay, a set of 10 for $10. They are replacement brushes for the bosch colt.
The serrations are how the brushes came, and I would guess its to help set the brushes quicker.

For the wire connection, I took one of the little disks off the spring on the brush, and soldered it to the wire,
and slid it through the 'holder' (hope thats making sense - see post #4 - on the old brush holder)
The spring and brush slide into the holder and makes contact with the soldered disk.
When I assemble everything, I kinda hold the brush into place as I line things up, pop the lid
back on and replace the screw. The springs keep everything contact, and in place.

I'm out on tour and wont be home till Mid Dec to take some better pics, so here's a cheesey paint pic

[GTFreeFlyer]

Cool. Makes sense. Thanks. How much would you charge for the 3d printed part and matching spring?

[GTFreeFlyer]

Haha, Mogal I just saw your private message now, after I had already asked the question above. Thanks for thinking of me and updating me back in June!

I just adapted the carbon brush to the router. Continuity checks are all good. It's late and I'm heading to bed before turning the router on and doing some trial probing with it. I'll share pictures when I get them uploaded. I may have found a simpler solution.

By the way, have you found any good probe bits? I'd like something with a 1/4" shank, but then necks down to a very small diameter and then has a tiny sphere on the end. Any ideas?

[GTFreeFlyer]

So here's what I did:

1. I ordered the replacement carbon brushes for the Bosch Colt.
2. After removing the router's cover, (first photo) I enlarged the hole above the spindle and drilled a small hole next to it for a screw.
3. I bent a small piece of copper strip to form a right angle bracket and drilled a small hole in one of the legs for a screw (2nd photo).
4. I soldered the bracket onto the frame of the carbon brush (3rd photo), and I also dropped solder in the top of the carbon brush's housing to prevent the top retainer from popping out.
5. I cut off the pieces of the housing that are not needed (4th photo).
6. I attached the assembly to the top of the router with a small screw (5th photo).
7. I cut an opening in the top cover of the router to allow the assembly to protrude out (6th photo), and then soldered the ground wire from my CNC machine to the top.

I now have electrical continuity from the tip of the cutting bits all the way to the top. It took me about 30-45 minutes and I'm looking forward to trying it out!

[GTFreeFlyer]

So far so good! I've run the router for longer than it took to wear out my other attempts. These carbon brushes seem to be very promising. I have not taken the router cover off yet to inspect, but I'm assuming all is good. How long do these brushes last for? I'm concerned about a buildup of conductive carbon dust inside my router, and more importantly for health reasons. I've never dealt with these brushes before. Anyone have a clue?

[Ynothna]

I know this is an 8 year old post but I needed to thank you guys for all the work you put into this. I've been having a problem with the router on my CNC building up a static charge that has ended up affecting the Z axis steps in the middle of jobs. I've also been wanting to setup gatorless leveling so this is a 2 for 1 win for my setup. Will be testing it out this afternoon, fingers crossed!