Zzero failing

[kenakabrowncom]

Hopefully someone has an idea on this...

BT48 Buddy with spindle

I have had my buddy about 4 years and this just started happening ... getting worse and worse but intermittent.

When running C2 the spindle goes down and does not sense that it's hit the plate. I jams down on the plate and table for a moment and then fails the zero.

I can touch the plate to the bit and the indicator in the control software will sometimes show contact and sometimes not. While holding the plate to the bit I can move wires around to see if there is a loose wire but nothing changes....

Again, this is intermittent. I have even seen times where I can test the contact, it works with the bit above the table and then running C2 it still fails.

I am not using the alligator clip because of the spindle... the clip was removed day one.

Running out of ideas... everything else is working fine... once I can get a successful zzero.

Thanks!

[jerry_stanek]

I think it is not always making a complete circuit. You should replace the clip and use it.

[garyc]

Ken...
Along with adding the clip, sand the plate with 80 grit paper to ensure a good contact. Some bits, especially when coated or used, may not be as conductive as a new one.

Make sure that the bit to plate is 100% reliable prior to running the C2 routine.

[beacon14]

Check the wire to the z zero plate for broken conductors or hidden damage.

[toy1]

Hi
I had the same problem with my machine it is about 4 years old and did the same thing, I went and grounded all of the axis of the bot and it did improve the situation 99%, what I think is happening is as the machine gets older the ground potential startes to go away.
if you look at the design of the SB, it has rolling contacts in which the v-groove bearing rides on a v bar in theroy you have great contact force you have the weight of the Y carriage and that should give you enought contact pressure to maintain a good ground thru the machine, however when you add sawdust and some humidity and the machine starts to get oxidation/rust you loose ground and now you get stray voltages not able to get to ground and you get these errors random in nature. I find as the temp in the shop gets higher the errors go away the cooler it is the more errors I believe that is due to humidity goes down and you get more static in cool temp.
So make sure your grounds are solid.

that took care of my issues, there were days I put the contact plate way and used a shim to set cutter height.

there are alot of post on grounding, best thing you will ever do.

[kenakabrowncom]

Thanks Carl and Gary... will look at both.

Grounding was a big issue (or we thought) when the BOT was new... but will go back again and review that.

Interesting thoughts on the background you went through Carl.. thanks!