Is it not possible to make a probe that is insulated from the mill if the work piece is not insulated? Would this not do the job?
Willy -----Original Message----- From: vavaroutsos [mailto:[EMAIL PROTECTED] Sent: zaterdag 23 oktober 2004 21:25 To: [EMAIL PROTECTED] Subject: [CAD_CAM_EDM_DRO] Re: Measuring backlash with a ohm meter Ron, I may have mis-understood what Chuck was saying, but I think he is measuring the electrical resistance from the work to the spindle, not the resistance to movement on the axis. This would require that the work be electrically isolated from the mill or the probe be electrically isolated. Things may have worked ok in Chucks case due to the construcion of the mill not providing much electrical conductivity from the spindle to the table, but I don't think this is a valid assumption for all mills. ~petev --- In [EMAIL PROTECTED], R Rogers <[EMAIL PROTECTED]> wrote: > Interesting concept. However what may seem absolute is often not. Measuring resistance upon contact is measuring the effects of a slow minute crash. Contacting a surface to the point the drive begins to struggle would not be touching off on an edge. Due to deflection. I'm not ruling out that this would be accurate. It would require testing involving the method you perscribed versus a conventional edge finder. If the results parallel that would be a great edge-finding technique. Design into a machine control software to enter a setup screen that when resistance is sensed upon a drive it would automatically zero that axis, spindle rotating as this is more accurate. Would need to be able to distinguish between touching and fast jog resistance measured. Could even have a compensation preset for the radius of the stylus. None for Z obviuosly. Possibly an extremely stiff die spring in the shank of the edge finder to prevent damage on over-travel. This would be alot faster than present > method. Sometimes when I'm in a hurry I just use the end-mill for the cut as an edge finder, step-jog to touch and then add the radius. > > For measuring backlash, a good dial indicator is pretty tough to beat. It's not something that is measured all the time. > > Ron > > > Chuck Rice <[EMAIL PROTECTED]> wrote: > > > > I just tried something and it seemed to work well, but since I am a > newbie, I wonted to pass it by the list to see if it might be useful > to others. > > I wanted to measure the backlash on my Sherline, so I attached an Ohm > Meter to my mill. One terminal to the bed, and the other to the > spindle. It read a resistance of about 2k ohm. Then I lowered Z till > a bit touched the surface of the milling plate and the resistance > went to zero. Then zeroed Z and micro-stepped back up till the > resistance went back to 2k ohm. Z showed .0012. To test, I lowered to > zero again and as Z hit zero, the resistance went back down. > > Using this information, it seems that you could devise an > edge-finding routine for any metallic object that would position the > bit exactly in the X, Y, and Z planes with respect to the object to > be milled. > > Has this been tried before? -Chuck- > > > > > > > > Addresses: > FAQ: http://www.ktmarketing.com/faq.html > FILES: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/ > Post Messages: [EMAIL PROTECTED] > > Subscribe: [EMAIL PROTECTED] > Unsubscribe: [EMAIL PROTECTED] > List owner: [EMAIL PROTECTED], [EMAIL PROTECTED], [EMAIL PROTECTED] > Moderator: [EMAIL PROTECTED] [EMAIL PROTECTED] [EMAIL PROTECTED] [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!? > vote.yahoo.com - Register online to vote today! > > [Non-text portions of this message have been removed] Addresses: FAQ: http://www.ktmarketing.com/faq.html FILES: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/ Post Messages: [EMAIL PROTECTED] Subscribe: [EMAIL PROTECTED] Unsubscribe: [EMAIL PROTECTED] List owner: [EMAIL PROTECTED], [EMAIL PROTECTED], [EMAIL PROTECTED] Moderator: [EMAIL PROTECTED] [EMAIL PROTECTED] [EMAIL PROTECTED] [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: [EMAIL PROTECTED] Subscribe: [EMAIL PROTECTED] Unsubscribe: [EMAIL PROTECTED] List owner: [EMAIL PROTECTED], [EMAIL PROTECTED], [EMAIL PROTECTED] Moderator: [EMAIL PROTECTED] [EMAIL PROTECTED] [EMAIL PROTECTED] [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. 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