Re: [CAD_CAM_EDM_DRO] Bleed Resistor... Do geckos need a fan?

Bob and Abby,

I use a 5 -10 ohm adjustable resistor set at 7 ohms for my E-stop circuit. It immediately dumps all 3 100 volt 25k capacitors and stops the servos. I used a variation of Mariss's E stop circuit. I had a little trouble understanding the drawing so maybe I have it as he outlined. I have a 110volt normally open and normally closed relay that controls the circuit. I use a normally open momentary "Start" switch and a normally closed momentary "E-stop" switch. I have a jumper from the coil of the relay that goes up to the normally closed Estop and "latches" the relay when I push the Start switch which energizes the coil of the relay. Then the whole control system is energized through contacts on the same relay. and when I push the Estop it drops the current to the coil in the relay and then "shorts" the caps with another set of contacts in the same relay through the 7 ohm resistor to dump the caps. I'm sure I made it sound more confusing than it really is. I think the schematic is in the
"files" section of this group. Anyways, it works great. Without this dump circuit when you do an E-stop the machine will not stop until the servos have bled down the capacitors. Depending on your configuration this could be quite a bit of distance. I hope this helps, Abby.

Just wanted to mention Bob, I'm using your Mach2 board and it is working great. 14 months of dust, chips, coolant and usual grime in the air of my shop and it has been flawless. My cabinet is completely sealed and it still gets in there <shrug>

I have my Geckos mounted on heat sinks without paste with fans and they stay really cool. I checked them quite often when I first started using the machine. Because I'm sure as everyone knows by now I'm driving the knee for Z with a 40lb/in servo with no gas springs or counterweights on the knee and even when I'm peck drilling it's never felt much over 120 degrees F. Normal milling they barely get warm on any axis. Although I didnt use paste they are mounted tightly on a very fine machined surface which I'm sure is helping the heat transfer. The paste is one of those "I'll get to that someday" deals. I'm not suggesting that this is acceptable, I'm just lazy and got away with it.

Ron

Robert Campbell <bob@...> wrote:
Abby,

I feel that a bleed resistor should be used to discharge the capacitor after
you shut off the power.

You defiantly need to use thermal paste. Without it you will not get the
proper heat transfer from the Gecko drive to the heat sink.

I always use fans in my control enclosures. You will also need to provide a
hole (with a fan filter and cover) at the opposite side so that air can come
in.


Bob Campbell
Bob@...
www.campbelldesigns.com
Breakout board
THC board sets
CNC router plans
Stepper Motors
VisualMill Basic

----- Original Message -----
From: "AbbyKatt"
To:
Sent: Tuesday, September 21, 2004 5:27 PM
Subject: [CAD_CAM_EDM_DRO] Bleed Resistor... Do geckos need a fan?


>I was wondering..
>
> Power supply is all nice and working now, and am about to hook it all up
> to the geckos.
> I was wondering: Do I need a bleed resistor across my cap? What happens
> if I neglect to put one in?
>
> Also, do I need a fan for geckos, I'm only going to be doing a peak of
> 12 amps @ 50V, and I have it already bolted to some nice aluminium. Will
> I need thermal paste?
>
> Thanks!
> ~Abby
>
>
>
>
> Addresses:
> FAQ: http://www.ktmarketing.com/faq.html
> FILES: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/
> Post Messages: CAD_CAM_EDM_DRO@yahoogroups.com
>
> Subscribe: CAD_CAM_EDM_DRO-subscribe@yahoogroups.com
> Unsubscribe: CAD_CAM_EDM_DRO-unsubscribe@yahoogroups.com
> List owner: CAD_CAM_EDM_DRO-owner@yahoogroups.com, wanliker@...,
> timg@...
> Moderator: pentam@... indigo_red@... davemucha@...
> [Moderators]
> URL to this group: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO
>
> OFF Topic POSTS: General Machining
> If you wish to post on unlimited OT subjects goto:
> aol://5863:126/rec.crafts.metalworking or go thru Google.com to reach it
> if you have trouble.
> http://www.metalworking.com/news_servers.html
>
> http://groups.yahoo.com/group/jobshophomeshop I consider this to be a
> sister site to the CCED group, as many of the same members are there, for
> OT subjects, that are not allowed on the CCED list.
>
> NOTICE: ALL POSTINGS TO THIS GROUP BECOME PUBLIC DOMAIN BY POSTING THEM.
> DON'T POST IF YOU CAN NOT ACCEPT THIS.....NO EXCEPTIONS........
> bill
> List Mom
> List Owner
>
>
> Yahoo! Groups Links
>
>
>
>
>




Addresses:
FAQ: http://www.ktmarketing.com/faq.html
FILES: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/
Post Messages: CAD_CAM_EDM_DRO@yahoogroups.com

Subscribe: CAD_CAM_EDM_DRO-subscribe@yahoogroups.com
Unsubscribe: CAD_CAM_EDM_DRO-unsubscribe@yahoogroups.com
List owner: CAD_CAM_EDM_DRO-owner@yahoogroups.com, wanliker@..., timg@...
Moderator: pentam@... indigo_red@... davemucha@... [Moderators]
URL to this group: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO

OFF Topic POSTS: General Machining
If you wish to post on unlimited OT subjects goto: aol://5863:126/rec.crafts.metalworking or go thru Google.com to reach it if you have trouble.
http://www.metalworking.com/news_servers.html

http://groups.yahoo.com/group/jobshophomeshop I consider this to be a sister site to the CCED group, as many of the same members are there, for OT subjects, that are not allowed on the CCED list.

NOTICE: ALL POSTINGS TO THIS GROUP BECOME PUBLIC DOMAIN BY POSTING THEM. DON'T POST IF YOU CAN NOT ACCEPT THIS.....NO EXCEPTIONS........
bill
List Mom
List Owner


Yahoo! Groups Links







---------------------------------
Do you Yahoo!?
Yahoo! Mail - You care about security. So do we.

[Non-text portions of this message have been removed]