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Re: Digitizing
« Reply #40 on: May 29, 2007, 02:37:31 AM »
Ha ha! I've been called worse names than Mike! (with apologies to everyone named Mike)

Please explain how one goes fishing for free anymore! Again: Ha ha!

I keep forgetting to make money. But I am hoping I can offer these things at a low price. I think it is possible using the materials I'm using. Lots of plastic. Plastic is really fast and easy to machine. This will be a poor man's probe in that regard, but I think it is plenty good enough, at least for the hobbyist. I seem to get really good repeatability on measurements. I will have to do a lot more tests so I can come up with some good figures on how accurate it is.
-Mark

Offline Chaoticone

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Re: Digitizing
« Reply #41 on: May 29, 2007, 02:46:45 AM »
LOL, Listen, break a limb out of a tree, tie a string and hook to it, dig up some worms or catch some crickets, or grasshoppers, put them on a hook, lower the hook in the closest body of water. If you can't find a tree limb, you can tie the string to your toe.  ;D

I know what you are saying. I think it the screws for adjustment are great too. I hope you can offer them at a low price as well, I'm just saying, make it worth the effort.

Brett 
;D If you could see the things I have in my head, you would be laughing too. ;D

My guard dog is not what you need to worry about!

Hood

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Re: Digitizing
« Reply #42 on: May 29, 2007, 02:55:38 AM »
, you can tie the string to your toe.  ;D
Brett 
You mean you actually use 13 lines at one time or do you just use one of your toes ;)


Tetra
 nice idea on the probe, i had a different way of doing this but so far have not had time to finish it, but yours looks easier. It would however need a redesign of my probe from the ground up to do it your way :(
Hood

Re: Digitizing
« Reply #43 on: May 29, 2007, 03:15:00 AM »
Brett, Thanks for the fishing lesson. Yes, seriously, I will try to make it worth my while.

Hood, Yeah, I kinda like it. I need to finish my plan drawings, which means I have to finish making my latest revisions on the prototype, which means I will probably end up changing the drawings again. But I think I'm really close to finalizing it. Trying to make it as simple as I can so it can be made easily.
-Mark
Re: Digitizing
« Reply #44 on: May 29, 2007, 08:04:10 AM »
Hi Mark,

I have been following this thread for a while. I appreciate the work you are doing and the time you are taking to get this thing working correctly and accurtately. One thing that has intrigued me about all this is the software you are using to manipulate your point cloud. I did a search and found it but would like to ask a couple of questions. I feel this is pertinent to this thread since it does us no good to get a point cloud and have to way to use it. I have imported into Rhino and have one product we modeled from those points but the time involved was too long.

Can, or would you be willing to do a quick overview of the map software that you use as well as the steps taken and the type of file you end up with? For instance, the portion of the coin that you captured. Is that a machinable surface that you created?

Mike
Re: Digitizing
« Reply #45 on: May 29, 2007, 08:11:20 AM »
, you can tie the string to your toe.  ;D
Brett 
You mean you actually use 13 lines at one time or do you just use one of your toes ;)


Tetra
 nice idea on the probe, i had a different way of doing this but so far have not had time to finish it, but yours looks easier. It would however need a redesign of my probe from the ground up to do it your way :(
Hood



Hood is your's the one that has all the electronics on the outside of the body of the probe? The one that looks like some sort of space gun or something? If that's your's, then I think the melding of the two designs would be a huge step forward. The one with the electronics stops the false triggers with the probe stuck in an open situation and crashes into something. I just read last night that another person on the zone had crashed their probe.......though I think it was due to another reason.

Mike (no offence taken on the name March) ;D
Re: Digitizing
« Reply #46 on: May 29, 2007, 01:32:31 PM »
Mark,
Your design is very clever and it is nice to be able to calibrate it to zero.   It might be ideal for mill. 
It is amazing the resolution you got in the scan.  I am also interested to learn more about you “mapper”
software but right now I got to learn how to use Mach-3 first.    Life is full of compromises and it is especially true in engineering.

I suspect by adding the adjustments there is a tradeoff in stability and long-term accuracy. 
There are simply more items that affect the absolute position of the probe tip.

A careful reading of the patent that I referenced, indicates that they know what they are doing. 
I am sure the “insulating layer” refers to anodized aluminum to mount the balls repeatable and
they are soldered the as we discussed.  Note, the balls are selectively gold plated but not the whole ball since the gold is too soft.

In other words, do we want adjustability and convenience or super accuracy and stability.  A lot of these
probes are used on CMM machines were the absolute accuracy is critical.  On a regular CNC mill the home
made probes might be more accurate than the mill can resolve.   The high-end probes are looking
for 1 micron errors or less so the design rigidity is critical.


One possible compromise is to lock the balls in place and let the whole housing slightly move in
X-Y plane on the mounting spindle. It would preserve the rigidity and give a way to adjust it. 
We only need to be able to move it a few mils or so.

Many years ago I did a single axis probe using 3 balls with a forth one resting on top as a pyramid,
shorting the three together.  I electronically detected when the top ball was pushed off by a rod
from underneath the pyramid.  It worked very well!

I enjoy challenges to push for high accuracy or other similar functions.
Bertho

Offline Jeff_Birt

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Re: Digitizing
« Reply #47 on: May 29, 2007, 02:12:29 PM »
The old Brown and Sharpe CMM I have has a 19.1mm (?) dia. refernece sphere that you use to calibrate the probe before measuring.  Perhaps something similar could be done with Mach? 
Happy machining , Jeff Birt
 

Hood

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Re: Digitizing
« Reply #48 on: May 29, 2007, 02:19:58 PM »

Hood is your's the one that has all the electronics on the outside of the body of the probe? The one that looks like some sort of space gun or something? If that's your's, then I think the melding of the two designs would be a huge step forward. The one with the electronics stops the false triggers with the probe stuck in an open situation and crashes into something. I just read last night that another person on the zone had crashed their probe.......though I think it was due to another reason.

Mike (no offence taken on the name March) ;D

No, dont think so, mine just has an internal circuit with a battery and LED for edge finding use and a jack socket for connecting to Mach if it gets used for probing. Heres a few pics.

Offline Chaoticone

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Re: Digitizing
« Reply #49 on: May 29, 2007, 03:31:26 PM »
Looks good Hood.

Brett
;D If you could see the things I have in my head, you would be laughing too. ;D

My guard dog is not what you need to worry about!