Probe tip size

[ssflyer]

Hi all,
I have a job reproducing some old gargoyle and lion corbels, and need to get really good resolution from the ShopBot probe. Has anyone tried sharpening a tip to fit into tighter places, and would there be any downside to it? Since I'm not cutting it directly from the sbp file, but converting and importing into a CAD program, then Aspire, I don't see why it wouldn't work...

Thanks and best regards,
Ron

[courtney2018]

I haven't gotten my machine yet, and I'm getting the probe with it. Can you change out the probe tips? I used to use a CMM that had different tips sizes. If the shopbot probe tip can be changed out it might be a standard size thread like M2, M3, M5, etc. If that's the case you can get replacement probe tips going all the way down to 0.008" OD I saw. Some were pretty pricey, but I saw some in the $50 range.

Check out: http://www.google.com/search?sourceid=navclient&ie=UTF-8&rlz=1T4GGLL_en&q=cmm+probe+tips (http://www.google.com/search?sourceid=navclient&ie=UTF-8&rlz=1T4GGLL_en&q=cmm+probe+tips)

[billp]

Ron & Courtney ,
It might take a little trial/error but I can't see why it wouldn't work. I have done some fairly intricate probing in the past and the major drawback is TIME. The more intricate your item, the more hours you'll be tying up your machine.
A few years back I had a machinist turn a longer probe tip for me. All he needed to know was the thread sizing, and he was able to give me a very good tip. So if you can't find a commercial replacement tip, you might be able to have someone create one for you. I seem to remember that either McMaster Carr or MSC had CMM tips in their catalogs that would fit the Shopbot.
As anyone who has used the probe will tell you; practice a little bit with your setup before you put something highly detailed on the table and then go off to sleep. You'll have to learn how to set your height clearances, and proper touch distances, etc. or you will show up at the machine the following morning and see that your file stopped an hour after you left the shop, and your stylus now looks like a fish hook.
Depending on how you plan to use your machine it may make more sense in the long run to have someone else scan the file for you, so you can concentrate on cutting. It is not unusual for very detailed scans to run into days of probing.

[ssflyer]

Yep, I have the 3 different sizes that ShopBot offers: 2mm, 1/8 and 1/4", I believe. I'm not sure of the thread size, I'll have to check. Thanks for the link - I'll do some research.

The only real issue that I can see from thinning the 2mm tip I have is if the point got off-center. Please correct me if I'm wrong!


Thanks,
Ron

[ssflyer]

Thanks Bill,

I happen to be the proud owner of a 1/8" fishhook tip! The tips are actually pretty strong - I was amazed that the probe, with its plastic body was still just fine ;-}
I practiced on quite a few simple items after that to get it reasonably well figured out.

I've already probed one of the lion heads, but wasn't satisfied with the resolution - the tip simply wouldn't fit into a lot of the areas.

[rb99]

Going off center shouldn't really matter because it will all be off center...?

RIB

[billp]

I would think someone with a metal lathe should be able to turn that down so it's "balanced". If so all would be well.
If it is NOT balanced then you might have some distortion in one axis (for example if the tip is fatter on one side than the other it may not show up in a "Y" touch move, but it could alter the data in the "X" direction...).
Can you post a picture of your lion head so we can see just how intricate the problem is? Or is it proprietary? There are just times when you have to deal with the fact that the probe can only do so much, and then you have to go in by hand (or other tooling) to finish the job. This is not altogether bad when you consider the time frame involved if one had to do the entire job by hand.
I'll attach a picture I have shown at many Camps which shows what I mean. The customer had a "rush" job to build a project and he estimated it would take over 50 hours of hand carving. Instead I used the Shopbot probe for 17 hours and gave him something which he was able to complete by hand in under ten hours. Figuring the value of his time compared to what I charged him, he came out well ahead, didn't have to do the "dog work", and he easily met his deadline...

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[courtney2018]

I remember seeing an article in Make Magazine, and if you don't already get it you should. They've got some really cool articles in there from time to time. Also have a full page advert in each issue from Shopbot.

Ok, I remember a while back someone taking a wine glass, a lazer pointer, a turning stool, a video camera, and a computer to scan a persons face in 3D.

http://www.instructables.com/id/3-D-Laser-Scanner/

Watch the video.

The guy also makes the program available to download for free, but the program is a MatLab script. Chances are you don't have MatLab. There's a free equivalent software called SciLab, but you'd have to write your own script as I'm sure the two programs don't use the same scripting language. Unless you know someone that has MatLab (probably an engineer) this most likely wouldn't be a good option.

There's also a commerical kit you can get at relatively low cost: http://www.david-laserscanner.com "Relatively low" being the key word. But if you're going to be doing alot of this type of work the DAVID would be a cost-worthy option.

[ssflyer]

Thanks Bill,

Here's some pictures of the original, and the model in Aspire. I'll post a picture later of the first test run, cut only from the face (not 3 sided). It's actually not too bad, I'd just like to see how good it can get, within some semblance of reason ;-}


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Your job looks good, but my customer can't hand finish them and it would add a lot of time (read cost) to do them, myself. I have an order for ten, with possibly more similar items to follow, so I want to take my time on the model, and save as much as possible on the hand work.