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Re: Degree Wheel
« Reply #10 on: January 31, 2010, 04:59:42 AM »
New (and improved) version of the Degree Wheel. After routing a couple of pieces of wood, and then checking the wheel for accuracy, I discovered that it was anything BUT acurate!  So, I went back to the drawing board, and took even more time in CorelDRAW setting up a series of boxes to contain the characters in, so that a common point of origin could be accomplished. (There were slight differences in this in the orginal, therefore, even though snap was used- well, to quote a line from a movie "It would be impossible to discuss without a comman frame of reference").  The guide boxes yielded MUCH more acurate results. I also moved the witness marks to the outside of the circle, to open up more space between them (the space between the marks on the first wheel, were the same width as the envraving cut- a glorified SANDER).

Offline Tweakie.CNC

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Re: Degree Wheel
« Reply #11 on: January 31, 2010, 08:58:01 AM »
That looks sooo much better - good job you have done there.

Does it engrave OK ?.

( It seems that my version of LazyCAM thinks some of the numerals are not joined and makes a mess of producing the GCode - off to download the latest version of LC now  :'( )

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Re: Degree Wheel
« Reply #12 on: January 31, 2010, 12:10:22 PM »
Tweakie,
I have my Extents in LazyCAM set to 0.001" with Lead ins turned OFF, before Optimizing the file. I will let you know how it engraves, as I am about to take it out to the shop for a test drive. If you want a copy of the Plot file (CorelDRAW DXF export is a Joke!), let me know, and I will email it to you. I have already tried to attach the plot file, but the Machsupport Forum server doesn't like it for some reason. (Even though it lists *.plt as being a supported file format).
-Mike
Re: Degree Wheel
« Reply #13 on: February 02, 2010, 01:00:58 AM »
Well, I wanted to post a decent picture of the results of the Degree Wheel engraving. However, after many attempts it seems that 1 degree increments just ain't happening even with a depth of cut set to only 0.010"  I saw that Tweakie's design was set up at 2 degree increments, and actually did engrave with good results. So it seems that 2 degrees is the max.  Well, it was back to the drawing board one last time, (by now, I was obsessed with achieving 1 degree increments).

 I am not sure how many hours I spent on doing these total, the most time-consuming aspect was not the actual drawing, but rather the acurate rotation of each set of numeral characters in terms of degrees, in relation to the center of the wheel.

 To use this final design, a clear indicator pointer will be used, constructed of a small piece of clear Mylar, with a single scribe line down the center. The alignment scribe will be long enough to reach from the outer marks, to the inner marks, to that the end result will be 1 degree increments! (Note that both the inner, and outer marks are cut at 2 degree increments). They are simply offset 1 degree from each other. Also, the mark lines which protrude from the center of the hub are carved at the elusive 22.5 degree increments. Hope ya'll find this of use, as a LOT of work went into it.
-Mike

Offline Tweakie.CNC

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Re: Degree Wheel
« Reply #14 on: February 02, 2010, 02:50:01 AM »
Nice one Mike - I can see that a lot of work went into this. Good idea about offsetting the calibration lines and numerals.

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.

Offline RICH

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Re: Degree Wheel
« Reply #15 on: February 02, 2010, 09:03:54 PM »
ADPRINTER,

What you need to do is figure out, based on the depth pf cut, just how small of a "degree wheel" you can do.
For example: A scribed line cut at a very shallow depth 0.001" depth  will be about 0.003" wide and if if you figure
that you want the equivilant white spacing between the marks then line to line max would be 0.006" on the inner circle
of all the lines. So at 0.006" the min inner circle diameter would be around 0.006" x 360= 2.16" circumference.
2.16"/3.14= .687" min inner diameter.  Now additionally the smallest number heigth would be around 0.015" high.

Now the above assumes that the rotary / mechanical system  has the ability  / resolution to cut that spacing accurately.
So what you want to do is draw the degree wheel at say a inner circle of 1". Now you can scale the drawing up in anyway you wish for the min spacing you can do.

Yes to do it right you, create all the text first, then just rotate each and drag into position. Ie: you may wish to have it on the inside or outside of the marks.

The above way just makes it easier since you don't need to recreate the the degree wheel for reuse or aonther application.

One thing you can do is to write a re-peating sub-program for doing the lines using a rotary table. ie:
- Z feed
- X Y move to scribe one line
- Z raise
- move back to start point
- A rotate
 It will be reapeated  359 times.

Or you can have one that does the center lines, then another that does the 10 degree marks, and then another that does the lines in- between. So the code is realy minimized.
Then do all the letters in one shot.

Just some thoughts, to make it easier and reusable later,
RICH

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Re: Degree Wheel
« Reply #16 on: February 03, 2010, 10:03:03 AM »
Rich,
I appreciate the insight. However, I am actually CONSTRUCTING a rotary table. I agree, that if I already had one, your method would make the most sense. I long for the day when I can do it your way.

 My problem, was in doing the actual engraving in order to have an acurate means of measuring, and calibrating Mach3 to the 4th axis movements (once I can afford the 4th motor). What I have so far, is a simple gear box (consisting of a worm, and worm gear) with a 10 to 1 ratio.

 I simply wanted the degree wheel for mounting onto the output shaft of the gear box. This would allow me to monitor the actual rotation output for proper motor tuning in Mach3 to achieve the proper calibration in Mach3. I am still a couple of weeks away from ordering the motor for the 4th axis, but just wanted to do as much work as I could in preparation. Without a physical means of measuring the actual movement to the Mach3 commanded movement, it would be impossible to calibrate acurately.

 I think that the "Final Degree Wheel" I created will work for my purposes, since it now spaces the witness marks far enough apart from each other for a clean engraving, without removing material BETWEEN the marks. I have been working with Pine, which I am aware is a large part of the problem. However, I wanted to achieve the best results possible, before commiting a piece of aluminum (since I only have a single piece I can use for this). The Pine has been the practice material in preparation for the Final Cut in Aluminum.  -Mike

Offline RICH

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Re: Degree Wheel
« Reply #17 on: February 03, 2010, 10:47:46 AM »
adprinter,
Save yourself a lot of agrivation. Spend three bucks and buy a drafting degree templet and mount it on the shaft for quick checking. It will be ok to say around one degree. To check for backlash you can use an indicator just like a linear axis only you need to convert the non-movement to degrees and it may vary depending on the gear box you have. Another cheap way is to mount a $1 lazer pointer such that it points on the the wall some distance away.
RICH