# Power drawbar for mill



## fillister (Mar 22, 2022)

Hello, I built this over the last several weekends, it utilizes 1/2 guide rods and an 1.5 bore x 1" travel air cylinder with internal return spring and 3 air solenoids on a common manifold. It is controlled by a maintained push button for the down motion and a SPDT momentary spring return for the forward reverse rotary motion. The only real problem I ran into was that the down motion is so rapid it would dislodge the socket at the end of the travel limit. The simple solution was to open the existing socket keeper hole to a #7 drill and tap to a 1/4 20 for a set screw. 

No more problems with a dislodged socket.


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## pontiac428 (Mar 22, 2022)

Looks substantial!  Nicely done.


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## MikeInOr (Mar 22, 2022)

Looks good!  I would enjoy seeing a video of it in action if you are able to post one?

A needle valve usually does a good job of slowing down a pneumatic cylinder that moves too quick.


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## pontiac428 (Mar 22, 2022)

There is a video posted, in high-res! Look in and amongst the pictures.


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## fillister (Mar 22, 2022)

MikeInOr said:


> Looks good!  I would enjoy seeing a video of it in action if you are able to post one?
> 
> A needle valve usually does a good job of slowing down a pneumatic cylinder that moves to quick.


Unfortunately the video is sideways, I should have held it horizontally, thanks for the idea on the needle simple to implement.

Thanks


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## fillister (Mar 22, 2022)

pontiac428 said:


> Looks substantial!  Nicely done.


Thank you Pontiac, I appreciate the comment


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## davidpbest (Mar 23, 2022)

@ahazi should see this.


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## Shootymacshootface (Mar 23, 2022)

Not too shabby, outstanding actually. 
Might I suggest an adjustable valve to control the airflow to the cylinder? It moves a bit too fast for me, may be problematic over time.


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## MikeInOr (Mar 23, 2022)

Not having ever used a power draw bar; is it possible to have the impact wrench always connected to the draw bar even when the mill is running?  Does the top of the draw bar go into the head when the quill is lowered?... I have never paid attention.  It seems like my impact wrenches turn pretty freely when there isn't any pressure?... but also something that I have never really paid attention to.   Just curious.


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## ErichKeane (Mar 23, 2022)

MikeInOr said:


> Not having ever used a power draw bar; is it possible to have the impact wrench always connected to the draw bar even when the mill is running?  Does the top of the draw bar go into the head when the quill is lowered?... I have never paid attention.  It seems like my impact wrenches turn pretty freely when there isn't any pressure?... but also something that I have never really paid attention to.   Just curious.


Yep, the top of the drawbar does move down with the quill, so it ends up being disconnected anyway.

I've definitely seen versions of this though that ONLY have the left/right control, but that can prematurely wear the impact since it isn't getting oil (which is often in the compressor supplied 'air' if you have an oiler).


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## Janderso (Mar 23, 2022)

fillister said:


> Hello, I built this over the last several weekends, it utilizes 1/2 guide rods and an 1.5 bore x 1" travel air cylinder with internal return spring and 3 air solenoids on a common manifold. It is controlled by a maintained push button for the down motion and a SPDT momentary spring return for the forward reverse rotary motion. The only real problem I ran into was that the down motion is so rapid it would dislodge the socket at the end of the travel limit. The simple solution was to open the existing socket keeper hole to a #7 drill and tap to a 1/4 20 for a set screw.
> 
> No more problems with a dislodged socket.
> View attachment 401365


I want one.
How did you do it?
Do you have a plan from some source or is this your invention?
Super sweet!!!


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## fillister (Mar 23, 2022)

Janderso said:


> I want one.
> How did you do it?
> Do you have a plan from some source or is this your invention?
> Super sweet!!!


Hello Jeff,

It's a very simple gizmo, 
2 - pieces of 1/2 T6 plate for the round circular parts.
2 - pieces of 1/2 oil hardened drill rod.
1 - piece of 3/4 x 1 T6 bar or the top cross bar and heim joint connector.
1-  piece of 2 x 1 T6 for the manifold, these can be purchased premade but their 4 port.
A horror freight palm impact, I had an old one hanging on the rack in the garage.
2 - 1/2 x 1/2 flange bushings
3-  120 volt air solenoids as I already had 120 V in the control panel. 
2 - carling switches, carling switches are nice and smooth as opposed to switches at the box stores        which suck.
1 - 1.5 bore 1" stroke air cylinder with internal spring

There are many designs on the net and and long thread on this site. I just tried to simplify and make a clean design.

Yes I created a complete set of drawings, but I'm hesitant about posting anything on the net, I'm not accusing anyone here but I've seen way to many instances where a designers work is renamed and sold on ebay and facebook by some unethical creep.

This is a great site and full of very talented people, I'm  humbled by the comments.


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