# Power Drawbar Build for PM-728VT



## jlchapman (Apr 25, 2021)

Well, its time for me to build a Power Drawbar(PDB) for the PM-728VT.  It really sucks using the two wrenches.  I like the idea of holding the tool as I release it.  I also want a foot pedal to operate the PDB.  

This may not be a fast build, but I will share all the information I have and look forward to all my questions being answered.  Thanks in advance.

So far I have watched a ton of videos.  Franco, CNC4XR7, CRUDCNC, etc.  Lot of good information out there.

I have ordered the same 3 stage air cylinder that Tormach uses, CQ2100 X 12-3.  Really easy to order.  Should be here towards the end of the week.  Contact White Wu at email address: ppyz8@xinyipc.com.cn.  He creates an order line for you at Alibaba.  You can use Paypal so there is not any credit card concerns.  It was $267 shipped by FedEx.  If you just buy off Alibaba you pay alot higher price.

So to start, I needed to create a drawing for the threaded bolt holes on top of the mill.  I only need the holes on the top right to hold a bracket.  On this bracket would be standoffs going up to the plate on the air cylinder and an air valve mounting on the side of the mill.  I also have to keep the encoder mounting in mind.  More on that later.  

I did the drawing and 3D printed a template to see if I the drawing was correct.  Not a perfect fit but it will work for building the PDB.  The bolt holes line up, but may adjust the fitment of angles, bigger diameter around pulley, and such.  I'm a beginner to advanced at Fusion360 so my drawings suck.  They will get better over time.  I'm a Computer Programming Manager with a passion to machine parts and build things, electronics, cars, etc.







Stay tuned, more to come.


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## jlchapman (Apr 25, 2021)

I have also ordered some needed parts to build the drawbar from McMaster Carr.  I ordered the following:

Belleville Disc Spring - 9712K436

Threaded rod for the Drawbar - 98957A807

Coupling Nuts - 90977A190

I'm building the new drawbar similar to what I saw in the videos from CNC4XR7 and from Jim Kramer.  I'll create some drawings to show what I'm building.


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## jlchapman (Apr 29, 2021)

I got all the parts I ordered yesterday.  The air cylinder is a monster.

I measured the stack of Bellville washers at .712.  So, I turned one of the coupler nuts down to .453 for 1.1".  I also turned the bottom portion of the nut using a 5 degree angle for 1/4".  The picture of the nut  doesnt show this.  This barely leaves any material for the turned portion with a 7/16" threaded drawbar.  I may consider taking the Bellvilles out to .5 or buying some with a 1/2" id.  The id of the spindle is .50".  I will need a 1/2" sleeve on the threaded rod to take up the slack between the draw bar and the id of the spindle.


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## jlchapman (Apr 29, 2021)

I also removed the spindle.  If you wondering how to remove the c-clip,  just push down on the spring cup and slide the c-clip out.


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## koenbro (Dec 12, 2021)

Any followup? Very interested.


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## Cad cam man (Dec 26, 2021)

What does the air cylinder look like very curious about getting 1


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## feral_cat (Jul 20, 2022)

I recently got a PM-728VT.  I was going to make my own power drawbar.  I had looked at the one from Priest Tools... hmm..  not impressed at all.  So, I looked around for DYI plans and found this impact gun.  I ordered it just to have on hand for when I got around to making the power drawbar rig.  No need!  I just put an 11mm socket on it, put it on and use the paddles for F and R.  Because it's impacting, you don't even need to have a spindle brake.  $60 and done.   Easy.

Found it on amazon: NEIKO 30088A 3/8" Drive Butterfly Impact Wrench | 75 Foot/Pound Torque


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## koenbro (Jul 20, 2022)

feral_cat said:


> I recently got a PM-728VT. I was going to make my own power drawbar. I had looked at the one from Priest Tools... hmm.. not impressed at all. So, I looked around for DYI plans and found this impact gun. I ordered it just to have on hand for when I got around to making the power drawbar rig. No need! I just put an 11mm socket on it, put it on and use the paddles for F and R. Because it's impacting, you don't even need to have a spindle brake. $60 and done. Easy.
> 
> Found it on amazon: NEIKO 30088A 3/8" Drive Butterfly Impact Wrench | 75 Foot/Pound Torque



Very interested in this. Can you pls post photos of your set-up? Thank you 

I also had the 11 mm socket on top, but life got complicated when I also wanted to attach an Omron encoder. I put the encoder on top and used an open wrench but that was slow and annoying. 

So I got a Priest PDB (the entry level one with a single stage air cylinder) and works well. He uses a quality MAC air solenoid. I can post photos of my setup if there is interest. 


Sent from my iPhone using Tapatalk Pro


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## Tio Loco (Jul 20, 2022)

Wow, ambitious... here's my take:









						Super Simple Power Draw Bar for PM-728V-T
					

Those ratchets will be shot very quickly turning with the spindle.  That's exactly what I was thinking!




					www.hobby-machinist.com


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## feral_cat (Jul 20, 2022)

I'll bring my video recorder tomorrow and I'll make a video.  This is so painfully easy.  I might build some stuff to hold it someday, but you still have to reach for the in/out buttons.  Grabbing the impact wrench is like 10% harder so it's hard for me to justify spending any more time on it.


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## IamNotImportant (Jul 20, 2022)

I like this guy's set up..


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## koenbro (Jul 20, 2022)

I am using the Tormach TTS tooling system so rotation is neither necessary nor beneficial. All I need is push down and pull up — which is why I went with the combination of Belleville washers and a pneumatic cylinder. 

Nonetheless I am interested in your solution. 


Sent from my iPhone using Tapatalk Pro


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## feral_cat (Jul 21, 2022)

IamNotImportant said:


> I like this guy's set up..



That video works.  That's the same impact gun I got.  Notice, it is handheld and has a forward and reverse paddle.  You can easily hold it up there with one hand.  I like the handle he made.  

So, the way I look at it is this:  I can grab the gun, sitting on a peg by the machine, do it myself and it probably takes maybe 3 seconds longer.  I use this machine not a lot, so maybe 20 tool changes per week.  Over 10 years of use, that adds up to 8 hours of total additional time.  How many hours would it take me to make something to hold it and automatically engage/disengage and actuate the forward and reverse.  Probably half a week, so the payback is not there.  I'll keep doing it via the handheld method.


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