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Author Topic: Making the Sextus clock  (Read 1270 times)
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kit
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« on: October 31, 2017, 10:03:03 PM »

This is a short video showing the use of my DIY CNC router to cut out most of the parts for a Sextus clock from 7mm ply. The complete cut took about 90 minutes. The frame parts were also cut on the same machine from 12mm ply.
The plans arrived from Woodentim es as DXF drawing files and were imported into CamBam software for editting and generatin g the G-code for the router. The later part of the video shows the Roman numerals being cut for the modified dial. This was done using a 22 degree 'V' tool and the 'V-Carve' plug-in for CamBam.

I posted a video of the finished clock a few week ago.

This week the machine is cutting out parts for it's own next upgrade, after which it will be considera bly more rigid which will make it more accurate and allow me to run it a lot faster. It will also look a lot more professio nal as well with a lick of paint added to make the MDF less obvious (and less pourous which is the real point).

Kit

https://vimeo.com/240094760
« Last Edit: October 31, 2017, 10:28:04 PM by kit » Logged
ArtF
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« Reply #1 on: November 01, 2017, 06:45:33 AM »

Kitt:

 Long cut, nice work! Smiley

Art
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kit
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« Reply #2 on: November 01, 2017, 08:05:35 PM »

Art,
I was glad when 90 minutes of holding the vacuum cleaner was over, but that's still far less time than cutting it all out by hand. In it's current state the framework of the macine isn't robust enough to accuratel y cut the depths or speeds you would normally expect for this kind of work. Once the modificat ions are finished I'm hoping to double both which will greatly reduce the back ache. I don't plan to install a dust extractor at the moment, I don't have much space for it and don't do enough cutting to worry about freeing up the time. But never say 'never'.

Kit
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ArtF
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« Reply #3 on: November 01, 2017, 08:15:55 PM »

Kit:

 I hear that. I cant imagine cutting most of what I do by hand..

 I don't use a dust extractor either, I just periodica lly vacuum during the
cutting. Looks good though..

Art
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drezal
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« Reply #4 on: November 03, 2017, 11:09:13 AM »

Looking good.  I purchased the plans from Woodentim es for the Septimus clock a couple years ago.  At the time my DIY CNC wasn't up to the task; it just wasn't precise enough.  Over the last few years I've made a few different CNC machines some with more success than others.  Those CNCs have been great for different kinds of projects but not good enough for meshing gears.  I've have however enjoyed using Gearotic for some awesome gear projects that were not real critical.

I have an old 3040 CNC that has been modified over the years for various projects and am currently working on Clayton Boyer's Genesis Clock.  Most of it is cut and a lot of it is assembled .  However the 3040 is still slightly off - most likely due to a different stepper motor on the X and Y axis.  I've tuned them many times in Mach but it's still a hair off; say about 1/8 to 1/16 which makes escapemen t wheels difficult

Here's where the clock is currently:  https://www.youtube.com/watch?v=PFHPV8CtTaM
https://www.youtube.com/watch?v=XB2qP6KS8iY

Dan
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ArtF
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« Reply #5 on: November 03, 2017, 11:38:30 AM »

Hi Dan:

 >>I've tuned them many times in Mach but it's still a hair off; say about 1/8 to 1/16 which makes escapemen t wheels difficult . 

  You probably have a loose coupling making it sloppy, Mach will easily adjust for
two different motors with different step counts and rates. If you run the calibrati on on
it , it should adjust the counts so your less than .001 off typically .
  More likely mechanica l though than count of motors..

Art
 
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drezal
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« Reply #6 on: November 03, 2017, 12:24:16 PM »

Certainly could be that too.  Or a springy coupler as well; they seem to have a little more play than I'd like.  It's a bummer when it comes to really tight tolerance s.  What make CNC do you have and do you like it?  After building four CNCs from scratch and playing with this little 3040 I'd like a really tight machine.  One day.  When I can demonstra te to my wife that it is needed.  Wink

Dan
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ArtF
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« Reply #7 on: November 03, 2017, 05:14:08 PM »

My router is from way back in the earlier mach3 days, Chinese, but with cast iron gantry and nice ball screws. Very accurate. I think they were trying to learn how to make them cheaper but were still making them heavy at the time. Smiley

Art
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kit
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« Reply #8 on: November 03, 2017, 06:21:44 PM »

Dan,
Nice to see the clock coming along and I always like to see other people's workshops . They always seem tidier and better organised than mine though I suspect that is what we all say.

I'm surprised you have such large errors on the CNC machine even after several re-builds. You can see that my own creation is not exactly an engineeri ng masterpie ce but it did well enough to get the Sextus working. I agree with Art that you problems are probably looseness in the mechanics, the software can be calibrate d to get the steps per mm exactly correct.

 Issues I've had include end-end slop in the leadscrew on the X axis (the Y axis is currently belt driven) which needs care to get rid of and flexing of the rails I'm using. The later is why I use shallow cuts (2mm or less) and slow speed (800-1200mm/min) to keep the loading on the tool down. The current upgrade is all about reinforci ng the rails for both X and Y axes and making the whole gantry a lot more rigid.

Nice guitar playing too.

Kit

Kit
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drezal
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« Reply #9 on: November 03, 2017, 09:40:56 PM »

Hi Kit.  Thanks.  Each of the CNCs I've built have been sort of odd.  Many of them are shown on my YouTube videos.  Great job on getting the Sextus clock working!  That is a really cool looking clock. 

This evening I took apart a few sections of the small 3040 CNC and found a few mechanica l issues.  One of the bearings tends to stick ever so slightly causing a slight stutter.  There is also a tiny but measurabl e play in the Delrin bushing for the Y axis - I have the Y set up as the "long" run on the machine.   

I think we're all tougher on ourselves than we should be.  When I look at other people's shops and projects they always appear so much cleaner than what I make. 

Anyhow, always learning.

Dan
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