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

[Just for fun]

Those ratchets will be shot very quickly turning with the spindle.

That's exactly what I was thinking!

 

[Tio Loco]

I'm curious why that would be the case. I put an in-line oiler on the ratchet so it gets lubrication with every use, and the mill certainly does not turn anywhere near the native rpm of the ratchet under air power.

And as I wrote, the socket can be disengaged by just dropping the quill about 12mm.

 

[Jim F]

Undo wear in the motor cylinder and on the impact mechanism.
The motor cylinder is just flash chrome plated, they do not like running without oil.

 

[chipinator]

If you don't like the impact wrench setup, what's the alternative to purchasing an expensive custom power draw bar? Yes, I get making one, but what type? Tool(s)? Designs? I would like to be able to use R8 collet chucks to hold my tooling with the use of a power draw bar. Any suggestions?

 

[KVan]

If you don't like the impact wrench setup, what's the alternative to purchasing an expensive custom power draw bar? Yes, I get making one, but what type? Tool(s)? Designs? I would like to be able to use R8 collet chucks to hold my tooling with the use of a power draw bar. Any suggestions?

The idea was to have the impact engaged when the spindle is at the top most position. After making a bracket and using this design, I found that that when I frequently use the drilling function and raising the quill it wouldn't (at times) cleanly engage and make unexpected noise. Further more when engaged it would make a noise that was somewhat annoying, but that is easily overcome buy lowering the quill 1/2" as #Tio Loco pointed out. I also agree with #Tio Loco that most of the designs are way over thought and engineered. The unit I designed cost about $60 for the impact, materials and fittings. I've been using it for a few weeks now and it works like a charm.
You only need a couple of things to make this work, something to hold the impact wrench (and it doesn't take much since there isn't a lot rotational force) and some way to make it go up and down. Again, you don't need high compression springs to do this. I used 3/8"x 2 1/2" springs from Amazon and a 1" stiffer compression spring (Home Depot special) to add a little extra lift. My entire unit is held on with 4, M4 screws through 16Ga sheet metal. If you want to keep it really simple, just hand hold the impact (that's what I did during the build).
Any way you choose can't be wrong no matter how complex or simple, think about it, you get to conceptualize and design a part, make it using cool tools and machines, test it, refine it, and make it work. In my opinion that's what this hobby is all about.

 

[chipinator]

KVan - Where did you get the handle and base that's attached to the butterfly forward/reverse switch on the impact wrench? Did you drill and tap the butterfly switch to attach it? Thanks.

 

[KVan]

It was a part of the build, a scrap piece of AL and a 3/8" rod tapped and threaded and a ball mill to cut a grove. I took the paddle off the impact, drilled and tapped the holes for M3 screws, there's not a lot of force on this. The knob is just a 3D printed ball that is tapped or you can order one from McMaster-Carr knobs | McMaster-Carr. I actually did that whole setup as an after thought, the springs aren't really stiff, just enough to lift the impact, so I was just pushing the impact down and operating the butterfly.

 

[Tio Loco]

The idea was to have the impact engaged when the spindle is at the top most position. After making a bracket and using this design, I found that that when I frequently use the drilling function and raising the quill it wouldn't (at times) cleanly engage and make unexpected noise. Further more when engaged it would make a noise that was somewhat annoying, but that is easily overcome buy lowering the quill 1/2" as #Tio Loco pointed out.

KVan nailed it. My original design was a PITA to use. Noisy if the ratchet was engaged, and always fiddly if trying to use the quill for drilling multiple holes where you don't want the quill returning far enough to engage.

So, here's my take on V2. For the carriage, I used leftover parts from a batch of Amazon parts designed for 3D printer construction/repair. The 8mm rods worked out nice. Don't ask me how I know this, but don't try to cut them with a band saw, go straight to a cutoff wheel.

I replaced the linear ball bearings (crap) in the pillow blocks with self lubricating plastic ones called Drylin (

).

I initially bought springs from McMaster, but they proved too stiff. On a hunch, I dug into my RC truck bins and found springs that were a perfect fit. I considered a handle like KVan made, but for now I'm pretty happy with just operating the butterfly manually. Time will tell.

 

[Tipton1965]

Looks much better. Now you know why many of the impact wrench installations are way over thought or over engineered. Because they work better!

 

[chipinator]

Tio Loco...I would buy one if you made another. I need one for my PM-728V-T. I was going to make one but why reinvent the wheel.