3D probing in DOS

[mikejohn]

Is it possible running in DOS to do 3D probing with a "normally open " probe,using a Shopbot program?

.............Mike

[bill.young]

Hey Mike,

You can use the regular DOS probing routines with just a few changes. First, open the file in the editor or Notepad and manually change all the "ON INPUT(1,1)" statements (including ones that have a GOTO after them) to "ON INPUT(1,0)", and all the "ON INPUT(1,0)" statements to "ON INPUT(1,1)". They're kind of scattered around so make sure you find all of them.

Next look for a line that says "IF %(51)= 1 THEN GOTO CONTINUE1" and change it to "IF %(51)= 0 THEN GOTO CONTINUE1". This line might not be in all the DOS probing routines...I'm working from memory here... but if it's there it checks to make sure that there's isn't already contact when it starts up.

Save the new file with a different name and you should be ready to go.

Bill

[mikejohn]

Bill
Thanks. Which program? I seem to only be able to find edge-finding routines.
My alternative is to take this computer I am using now to the shop. I downloaded the latest software yesterday onto it. (My workshop computer is only happy with DOS. Like me, rather getting on a bit).I am worried that if I just swap computers my Shopbot may have a nervous breakdown!

(I still don't know what firm ware is)


...........Mike

[bill.young]

Mike,

Your DOS Sbparts folder should have "s_prb3d2.sbp" and "s_dxf3d.sbp" ... they're both 3d probing routines. "s_prb3d2.sbp" outputs sbp files and "s_dxf3d.sbp" outputs dxf points.

Bill

[mikejohn]

Thanks Bill, I will try it tomorrow, let you know how it goes.

.................Mike

[mikejohn]

Bill
You are truly a wizard!


4770

It did everything I wanted it to, and, after AutoCad I got this.

It was a coarse probe, x steps at 5mm (0.2"), y stepover at 3mm(0.14") Speeds of 25mm(1") and 12.5mm(0.5"). The head is 300mm (12") x 180mm(7") and it took just under 50 minutes to complete. 6mm probe for a 6mm ball bit.

We finish all of the heads (all of the rocking horse) by hand, as well as adding the fine detail, to give each horse an individual look, so we do not need to carve (and probe) any finer.
Thanks for the help, and a great program.

............Mike

[gerald_d]

Thank goodness you used a blunt probe - if it was sharper the horse wouldn't have lain so still for you!

[mikejohn]

If you look very carefully you can see where it twitched it's ear at the end of the cut.

[dvanr]

Hey Mike

6mm ball bit!?

Thats not a probe thats a cattle prod!

I think your "Romanian horse" looks more like this


4771


You asked about using normally open. Am assuming that you covered the head with foil , but that seems tricky. How did you do it?

[mikejohn]

Dave
As I tried to explain higher up, it was a very coarse probing. Everything we do on the Bot making Rocking horses (except the stands) is designed to create the basic shape.
The horses are then hand shaped to finish.
With the heads, we can see where the eye, eyebrow, nostrils, etc are, so simply hand carve a little deeper in those places to get the fine detail.
It is also fast.
One side of the head, as seen above, is cut in 13 minutes.

Covering in foil was suprisingly easy. I just gave Roxana some foil and spray on glue, and told her to get on with it!
(assuming that last question was serious, and not referring to a live horse. We actually made the horse lie still by putting lead in its ear. With a 12 bore!!)

..............Mike

[rhfurniture]

I trust your horse had a good life before his demise. I had to do that to my horse once. Very sad. Such wonderful trusting creatures, he let me hold him, as he wondered what the little black cylindery thing was in the man's hand, then booom. He had had a good life, just got rather old, run out of teeth, and got a bit too thin as a result.

r.

[bill.young]

Hey Mike,

I wonder if there's some very thin film material that's electrically conductive...something similar to mylar maybe? If so you could make a simple vacuum table using a shopvac, put your pattern on that, and then suck the film down tight to the surface. You would need to connect the film to the input switch connection...a wire and a screw through the film would probably be good enough.

Once you had done the work of making the vac table (which would really only need to be a box with some holes drilled in the top and a hose inlet for the vac) it would be easy to use and you wouldn't have to deal with gluing so you could use it on things that you didn't want to mess up.

Just a thought,
Bill

[gerald_d]

At this Easter time I am sure we remember those foil wrapped chocolate bunnies..... For the low resolution probing it doesn't matter if the foil is a bit wrinkly in places. When we did do a bit of probing years ago, it was enough to just wrap the foil over the edge without glue.

[mikejohn]

How am I going to keep bunnies from jumping about, to foil wrap them? It was bad enough with the horse.


Bill, I think something along the lines you suggest would be possible. Using a 6mm (1/4")probe, (cutting with a 6mm (1/4")bit) the probe will take up most of the creases
What I did get, however, was a number of 'double' hits very close to each other, which I am guessing being the probe pushing some loose material to the surface, then releasing it slightly higher than the surface as it backs off.

I was surprised at the overall points I got.
I had an x movement of 5mm (0.2") and y step-over of 3mm (0.14") and expected, looking from the top at the .dxf file a grid at those dimensions.
What I got was many more positions than that.
It makes the whole thing more accurate, it didn't take that long, and, as I said, I am delighted with the result.
But I do wonder what the x movement actually means?

Edited to answer my own question, I think. If the probe is moving towards an upslope, it will create a point everytime it touches the object (at the z resolution). If it is on a down slope, it wil stop every 5mm and touch down.
Is this correct?


............Mike

[den73160]

Mike,

Could you explain to a novice like me how you used a solid metal bit as a probe? Wiring? etc.

[mikejohn]

To all those who have emailed me, this is the method.
It is not mine, it appears in a number of places on the Forum. Gerald and Bill both have input on this.
If you connect a wire to #1 and touch it to the earth point on the control box, number 1 will light up.
It is exactly how the z plate works.
Replace the z plate with either a metal object, or any material object covered in alumimium foil. In my case it is a wooden rocking horse head. The foil was torn into pieces about the size of a playing card and glued to the wood with spray mount adhesive (the sort of thing you glue photographs down with). Extra foil was glued low down on the head to make a 'tail' to connect an alligator clip to.
Take a suitable sized metal rod that best matches your intended cutting bit.
I used a 6mm rod which niceley fits the collet, Gerald points out that you can firmly attach the rod anywhere on the z carriage.
Connect the foil covered model to #1, connect the rod to earth.
You use the software that says "normally open" which is opposite to the Shopbot probe.
From there on in it's the same as using the shopbot probe.
You need to stick the foil down well. If there was a metallic conducting paint, and you didn't mind messing up the original, this would be great. A probe with the same end profile as the intended bit would be perfect.
To sum up, foil to #1, probe to earth (ground) use the 'normally open' software.
acknowledgements again to Gerald and Bill

.............Mike

[gerald_d]

Mike, we always used one large piece of foil - didn't think that glueing pieces of foil together would make reliable contact? A search on the word "conductive" gives a lot of old info.

[gerald_d]

memory lane (http://www.talkshopbot.com/forum/messages/26/6094.html)

[bill.young]

Hey Mike,

(Sorry...I missed the question in blue above)

That is correct. On a perfectly flat surface (ignore the pointlessness of doing this for the moment!), the probe will lift up by the surface tolerance setting, move over by the X stepover setting, and then plunge to make contact.

If there is an upslope, though, the probe can make contact with the surface before it's moved over the full X stepover...in that case it triggers, lifts up to get a better contact angle, and then replunges. So you can get more points on that upslope side. On the downslope side it never makes contact as it's moving over so you only get contact at your X-stepover points.

If you don't want the extra "upslope" points try increasing the surface tolerance setting. In the DOS routine it's named "&surfacetol" and it's one of the setting in the Copy Machine.

Bill