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Using a pen as tool

PostPosted: Thu Jul 06, 2017 8:57 pm
by volkhard
After searching the forum I couldn't find the answer. Here my question:

Can I set up a tool with 0 rpm? I want to create a pen-holder which will be held in the spindle. Of course, the spindle should not rotate! Z axes is also not needed. Simple X/Y plotter function. Is that possible without too much workaround?

Thanks for any suggestions.

Re: Using a pen as tool

PostPosted: Thu Jul 06, 2017 9:02 pm
by PaulRowntree
I expect that you have an overide to prevent the spindle from turning. In any event, you will probably want to have a spring-loaded pen holder.

Re: Using a pen as tool

PostPosted: Thu Jul 06, 2017 9:08 pm
by dwilli9013
if a pen holder is fabricated to chuck into the spindle an allows the pen to be set at an angle that puts it back on center then one would not need to lock the spindle down. The design of the adapter would be similar to a drag knife. Spring loading the rig could be accomplished via the adapter shank you chuck up. Do a search on 3d printer pen adapters on google lots of info and techniques available.

Re: Using a pen as tool

PostPosted: Thu Jul 06, 2017 11:56 pm
by Pete Cyr
http://cosmos-industrial.com/index.php? ... ex&cPath=3
This guy makes what you want.

You can make a post processor to disable the spindle rotation (remove M3). Just copy one and edit it. You have to rename it inside the file as well (use notepad). If you have a router, just don't turn it on.

Re: Using a pen as tool

PostPosted: Fri Jul 07, 2017 8:08 am
by Adrian
Not sure about other machines but on a ShopBot if you have 0 rpm in the tool definition then it doesn't turn the spindle on.

Re: Using a pen as tool

PostPosted: Fri Jul 07, 2017 1:13 pm
by Leo
You will most definately need to use "Z" axis as well as "X" & "Y".

Pen Plotters as used in so many engineering offices, when pen plotters were all the rage, all used X-Y-Z to make engineering drawings. The pen always held perpendicular to the paper. Spring mounted for sure.

Definately a DOABLE thing to do.

Also - look into drafting pens. Felt pens worked also but wore out really fast.

Re: Using a pen as tool

PostPosted: Fri Jul 07, 2017 2:15 pm
by D.A.S.Ontario
I made a tool that is spring loaded, and will hold a pencil lead, a dremel diamond or carbide engraving tip. I have used it on glass, almost all metals, stone, and paper. my next attempt will be to adapt to a tip from a dollar store box cutter blade tip. you can have a look here, scroll to the bottom of the page. some of my attempts did not work very well. By the way the pencil lead is the type draftsmen used it is almost 1/8" dia and fits my spring loaded device. I also manually "0" my Z with a cigarette paper which is about .001 or so. You can view my attempts by clicking here ,
http://www.theschneiders.ca/cnc.html remember, scroll down,

Using a pen as tool

PostPosted: Fri Jul 07, 2017 2:47 pm
by Bobtail Farm
1/2" od aluminum tube to fit collet. pen selected for parallel sides of barrel and sliding fit inside tube. spring above for pressure to tip and o-ring to keep it from sliding out completely on "safe moves". Hat tip to Brian Oltragge (Grunblau design).

Re: Using a pen as tool

PostPosted: Fri Jul 07, 2017 10:11 pm
by mtylerfl
Adrian wrote:Not sure about other machines but on a ShopBot if you have 0 rpm in the tool definition then it doesn't turn the spindle on.


I didn't know that. Thanks, Adrian! I'll use that sometime.

Re: Using a pen as tool

PostPosted: Sat Jul 08, 2017 4:30 pm
by D.A.S.Ontario
On my ShopBot Desk top, the spindle speed is controlled manually not by the tool data base or by the shopbot software, there is a knob on the controller and a on/off switch, that's it.
I like the idea of the aluminum tubing, pen, spring, "O" ring idea, cool, keep things simple, good thinking.

Re: Using a pen as tool

PostPosted: Sun Jul 09, 2017 1:59 pm
by Sk8nmike
Printed Pen holder or you can machine it. Works great

https://www.thingiverse.com/thing:1765757

Re: Using a pen as tool

PostPosted: Mon Jul 24, 2017 8:53 pm
by Martin Reid
Sorry guys I couldn't help it.

Bought 6 pens for £1.00 because they have 1/2" rubber barrels. With few modifications to reverse the spring to make the tip spring loaded (CNC Pen.pdf attached for those interested)

Adrian - Older versions of Partworks / VCarve, the tool database will not let you set the spindle speed to zero - You are correct that latest version does.

Tried it out today, works a treat.

Sincerely and in good faith
Martin Reid

Re: Using a pen as tool

PostPosted: Tue Jul 25, 2017 3:49 am
by volkhard
Thanks for all the suggestions and hints.

For me it is less about the tool (-holder) as I want to experiment with more than just a plotter-pen setup. And while I am away from my machine I can't just do the try and error approach.

My thought (or question) : What happens if I set up a new tool in my library and put the spindle speed to 0 rpm? Would that still turn the spindle or not?

If not, that would be the best way to do it. The other approaches (changing the post-processor etc) might be more "dangerous" if forgotten. If a tool is named and setup accordingly (0 rpm) the spindle would never turn if this tool is applied. Does that makes sense?

Re: Using a pen as tool

PostPosted: Tue Jul 25, 2017 4:03 am
by IslaWW
In most cases the best solution could be making a separate postP for the pen or drag knife that does not turn the spindle on. Simply make a copy of the post that you currently use and remove the spindle on command from the header and new segment sections. There is postP editing info under the help menu.

With many Gcode machines the spindle on macro is "M3". with ShopBot it would be "SO,1,1" or "C6". Your mileage may vary. The reason I say this is that some VFD's are programmed with a minimum rpm and in those cases zero rpm wont work.

Re: Using a pen as tool

PostPosted: Tue Jul 25, 2017 4:19 pm
by mtylerfl
Can you just unplug the power to your spindle?