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Air Scribe Working great

Posted: Tue Feb 07, 2017 10:57 pm
by msimpson99
I thought I would share my latest air scribe forays.

Before messing with any of my larger CNC machines, I have the air scribe currently connected to a small CNC I built for a series of Servo Magazine articles I just finished.

I built a floating head where the weight of the scribe presents the perfect weight of the scribe on the metal plate. Where the head bottoms out I added some small springs that are preloaded with the full weight of the scribe. This allows me to adjust the actual pressure of the scribe by adjusting the Z-axis depth of cut. The deeper the Z-axis goes the higher the floating head raises off the springs, thus allowing me to adjust the pressure at the point.

My shop air is pretty much set to 90PSI so I did not need a regulator at the scribe. I have a 5 way valve with the full open exhaust spraying into a bottle just in case there is any oil back spray. The valve connects into my oil fogger and then to the scribe.
Here are a couple videos of the scribe in action:

Re: Air Scribe Working great

Posted: Wed Feb 08, 2017 5:09 pm
by acourtjester
I made a similar setup for my scribe, using spring pressure.

Re: Air Scribe Working great

Posted: Wed Feb 08, 2017 10:54 pm
by motoguy
I like that spring loaded scribe setup. Mine is free floating right now. Though I haven't messed with it, I should be able to just add weights to increase down pressure. Changing the springs on your setup would do the same thing.

Re: Air Scribe Working great

Posted: Thu Feb 09, 2017 9:07 am
by acourtjester
When setting up the scribe you just move the Z down to the pressure you want on the tip and zero out the Z dro.
The lift it up to about 1" and start the operation, the rapids will move the scribe around with out touching and run Z to "0" for marking.

Re: Air Scribe Working great

Posted: Thu Feb 09, 2017 11:13 am
by msimpson99
I want to be clear about my design which is different very different. My springs are on the bottom, so increasing the spring reduces the weight. My floating head is plenty heavy enough to provide the pressure needed to make the deepest marks. The springs were chosen so that they are loaded by the weight of the head. The ease up on the pressure, I deepen the cut a little.

Both work pretty much on the same principle, I tried the spring push version, but decided to try this one. I prefer the bottom type as it means I can use a simple servo or solenoid. to raise and lower the head if needed. I dont have to fight against a spring.