Indexer info for Jack

[cmagro]

Jack,

Here is some indexer info for you. Keep in mind the programs I use are written by me but you'll get some good ideas from this stuff.

My program does about 99% of the code and works from a drawing I produce in AutoCAD. My turnings are done in much the same way as Cut3D would do them..hogging out most of the material and then finalizing with a detail bit. I do not do turnings like you would on a lathes but more like a carving on a flat piece of wood.

One of the good things about my program is that it actually draws the bits on the screen. I can make manual adjustments if needed before outputting the code. Here is a screen shot of the turning showing the 1/2" hog bits and how they will move.


9003

Here is a screenshot of the final pass.


9004

Here is a closer shot...the magenta is the bit itself and the cyan is the center of the bit.


9005

I go in and manually adjust any bit locations I need (especially in the tight corners). Being able to see the actual bit makes it very easy and foolproof.

I then create the tool path...it creates a back and forth path and outputs all the code. Here is the path.


9006

Here is a sample of the code used to hog out most of the material..It's quite simple outputting of the start point, end point and depth of cut. It loops around the blank and moves back and forth. The entire newel hogging out takes about a half hour.

'Information from each bit location is extracted and stored in variables.
&DEG=0
&STARTPTX=37.1562
&ENDPTX=39.0000
&ZDOWN=1.2812
GOSUB SUB_EXECUTE
''''''''''''''''''''''''''''''''''''''''''''''

&DEG=0
&STARTPTX=37.3437
&ENDPTX=39.0000
&ZDOWN=1.1562
GOSUB SUB_EXECUTE
''''''''''''''''''''''''''''''''''''''''''''''

JZ,&ZUP
J2,0.000,0.000
END


'Stored info is sent here which simply removes the material.

SUB_EXECUTE:
JZ,&ZUP
JX,&STARTPTX
JZ,&ZDOWN

'Loop in ten degree increments
LOOPVALUES:
&DEG = &DEG + 10

'Keep going until blank has made full turn
IF &DEG > 370 THEN RETURN
GOTO ROTATEANDRUN


'Hog out material forward and back...send back to loop
ROTATEANDRUN:
JB,&DEG
MX,&ENDPTX
&DEG = &DEG + 10
JB,&DEG
MX,&STARTPTX
GOTO LOOPVALUES

''''''''''''''''''''''''''''''''''

As far as the spirals....I simply locate the bit I will be using on the drawing itself and tell the program the rotation and number of spirals.


9007

Usually a 360 degree spiral works quite well for my newels and this particular one has four spirals..which means one every 90 degrees.

Here is the entire output code for the tapered spirals on this newel.

SA,
&ZUP=2.5000
JZ,&ZUP

J2,19.5000,0.0000
ZB

MZ,1.4375
M5,33.7055,0.0000,0.8260,,-360
JZ,&ZUP

''''''''''''''''''''''''''''''''''''''
J2,19.5000,0.0000
JB,90
ZB

MZ,1.4375
M5,33.7055,0.0000,0.8260,,-360
JZ,&ZUP
''''''''''''''''''''''''''''''''''''''
J2,19.5000,0.0000
JB,90
ZB

MZ,1.4375
M5,33.7055,0.0000,0.8260,,-360
JZ,&ZUP
''''''''''''''''''''''''''''''''''''''
J2,19.5000,0.0000
JB,90
ZB

MZ,1.4375
M5,33.7055,0.0000,0.8260,,-360
JZ,&ZUP
''''''''''''''''''''''''''''''''''''''


This particular newel was done with the zzero at the center for everything by the way.

I've seen a few posts about zeroing to the center of the indexer...some methods pretty fancy. My method...plane down a scrap piece of wood..put it on the table and line it up.


9008

Here is the newel after it has been hogged out...


9009

Here is the final shaping in progress....


9010

Newel is shaped and spirals are underway...


9011

Notice that I leave the top of the newel (where it would be pinned)...


9012

The newel pin is only 3/4" and that's just a little too weak for the weight and length relative to the pressure of the bit.

It means I need to change the bit back to the hogging bit to get the final.....


9013

That's fine because it's the final step and it's the bit I need for the next newel anyway..

Here is the final...


9014


9015

Total hog out was around 1/2 hour....final shaping was about 2 hours. I was doing other work so the rotation increment was set to one degree...I could easily have used two degrees and had the final shaping done in half the time. Setting the increment to one degree required no sanding at all (although I usually take a 220 grit and make it prettier).

Hog bit is a standard 1/2" straight bit
Final bit is a standard 1/4" round nose
Spiral bit is a standard 5/8" round nose

Hope this info helps you and answers some of your questions about using the indexer...

Christian

[myxpykalix]

Christian,

This is some very interesting and informative stuff here. But of course it just create more questions, so here goes.

So you design your part in autocad.

Then you take this software of yours (like millwizard or others) and that generates your toolpaths based on the design of the part.

You do a roughing and finish pass.

THEN you do a spiral pass. But it looks like when you created your paths you took some material off in the "field" where your spirals are to be located (8th picture down) so do you (knowing the depth you are taking out of the field) lower your depth of cut for your spirals, or am i overthinking this?
How many total toolpaths did you have?

And have you had any luck creating a "rope molding" spiral like this?

9016

I will look at this again with "fresh eyes" as i'm having problems with my indexer making tapers instead of rounding and i was working on trying to solve that mystery.

This information is very much appreciated, I know how much of a hassle this type of stuff is to do. I will have more questions tomorrow i'm sure. Thanks again...

[cmagro]

Jack,

Things like spirals and fluting are done after the turning. I would turn a newel first (and sometimes take it off the indexer). Maybe at the last minute the client wants spirals or fluting.

Spirals and fluting are very easy to do...the rope moulding in your picture is just a tighter spiral using a round over bit.

Send me some of your actual pictures, code etc. of what you are trying to do and I'll take a look.

Christian

[cmagro]

Your comment...

THEN you do a spiral pass. But it looks like when you created your paths you took some material off in the "field" where your spirals are to be located (8th picture down)

That is not correct...there is nothing special going on with regard to spirals. I would never embed my spiral code in the main shaping. There are so many variations of a spiral design I want to do that part separately.


9017

This picture is nothing more than a 1/4" round bit going back and forth with the final shape..it's exactly like Cut3D would do it.

If I wanted to add spirals to a tapered newel I had on the shelf I would mount the newel..put in the bit I want to use and manually locate it where I want it to start with the bit just touching the material. Let's say that point is 24,0,0 (the last zero is the top of the material.

Then I would manually move along the x axis to where I want the spiral to end..let's say 36"...the material would obviously be lower at that point since it is tapered. Then move the Z down to where it hits the material at THAT location which would actually make the point 36,0,-1.0 (a one inch taper)

Keep in mind I'm working from the top of the material and not the center....no need to get complicated with the math.

Now that you have those points you decide how far down you want the bit to go into the material...let's say .25 into the material.

so..
The starting point is 24,0,-0.25
The ending point is 36,0,-1.25

Got that?...if you were to write this..

JZ,0.5
J2,24,0
MZ,-0.25
M3,36.0,0.00,-1.25
JZ,0.5

You would make a flute...then if you rotate your blank...say...every 60 degrees and run it again you would end up with a six fluted newel (i.e. 360 devided by 60). I could grab a plain tapered newel and flute it in just a few minutes.

The only difference with the spiral (or rope) is that while you are fluting you are rotating the blank...that's it. How much you rotate it is a matter of preference and practice.

Changing the M3 to M5 and adding a rotation and there is your spiral.

JZ,0.5
J2,24,0
MZ,-0.25
M5,36.0,0.00,-1.25,,360
JZ,0.5

To me...it sounds like you are thinking too much and too deep / complicated. My type of work requires me to create custom stuff on the fly. The simplicity of Shopbot and the ability to throw some quick code together is why my bot works full time and my old boss's Thermwood C42 machine has been collecting dust for the past year.

The home page of Shopbot says "What would you like to make today"..it does not say "What would like the Shopbot to make today". This is a big difference in my eyes...it's a tool and a very simple one at that (X,Y,Z).

Rope moulding...tapered turnings....

M3,24,0,0
M5,36,0,-1,,24000

There is your tapered turning..a one inch taper over the length of 12".

If you are able email me with what you are doing and I will show you how to grab your bot by the balls and have make what you want in no time.

Christian

[dana_swift]

Christian, Just admiring the simplicity of your method. The combination of CAD and direct programming with the M5 command.

Did you program the toolpathing in VB or AutoLisp from within AutoCad? Or do it in an external program?

You are getting me itching for an indexer!

D

[cmagro]

Dana,

This particular program was done in AutoLisp. It works like a scanner flying across the path pinging points downward retrieving the Z height. The bits are drawn and then I go in and touch up the ones at some of the corners. Then it's a simple matter of creating a selection set of the bit center lines and organizing the points to form a path (note that curves are segmented...it's so much easier to work with and the resolution is just as good).


I've worked with AutoCAD since version 1.2 and found out I had a knack for writing macros back then. I had just graduated from architecture and was always the CAD Guru in the office. I actually still use Norton Editor (remember that one?) in a DOS window for a lot of quick stuff...if it ain't broke...

Most of my work is done in AutoCAD first and then I either manually write the bot code or use a program I wrote because I had time to do it. The ability to send a drawing to the client quickly works well.

And most of the programs just ask you to select a path or profile without an interface (program already knows what I want since it was not written for distribution).

If I need an interface I use VB and create an AutoCAD object. I stopped upgrade my AutoCAD at release 2000 (if it ain't broke....again) since it gives me everything I need.

I must say if I had the time I would write a really cool indexer program that would make Jack's life easier. The entire program is already in my brain.


Christian

[myxpykalix]

Christian,
Is this pgm "AutoLisp" a program within AutoCad or something stand alone? It looks to me like it is a series of spaced Z points that are formed to make the profile you seek. I guess it somehow links those Z's to make a x,y,z path, or is that done with some other pgm?

[cmagro]

AutoLisp is a version of Lisp just for AutoCAD. It has always been built in and is quite powerful.

Yes the profile toolpath is a series of z points and my program simply starts at one end and extracts the x,y,z info from the center of the bit.

If you use Cut3d do a sample output and look at the code...even the fancy carvings are done this way...just a bunch of little points.

Christian