PM-30 Z-axis power feed?

[davek181]

Thanks again. I may do the same. I had considered cutting a tapered hole and boring the hex shaft large and deep enough to slip a nut on the shaft to pull it into the taper much as the original wiper arm was done. Your way seems easier and if the torque load is low enough the pinning should be enough in addition to the taper.

I just need to accumulate a couple more pieces and I can begin the build. I had thought hooking up to the mill itself was going to be the hard part but I think I have that all figured out. I have a lovejoy coupling coming with a 14mm bore and a slit side to tighten it up on the shaft. I intend to remove the top locknut off the mill and thread the lovejoy fitting to match and then cinching the slit tight to hold it.

 

[acruxksa]

Thanks again. I may do the same. I had considered cutting a tapered hole and boring the hex shaft large and deep enough to slip a nut on the shaft to pull it into the taper much as the original wiper arm was done. Your way seems easier and if the torque load is low enough the pinning should be enough in addition to the taper.

I just need to accumulate a couple more pieces and I can begin the build. I had thought hooking up to the mill itself was going to be the hard part but I think I have that all figured out. I have a lovejoy coupling coming with a 14mm bore and a slit side to tighten it up on the shaft. I intend to remove the top locknut off the mill and thread the lovejoy fitting to match and then cinching the slit tight to hold it.

If I was worried about torque, I would have just welded it. The motor is super common and the part is just 1" round with some threads, a small taper and a 5/8" hex machined into it. Probably $45 and an hour to replace (now that I know what I want ), so it wouldn't have been a big deal to remake the entire setup if the motor failed.

I eventually realized that if I shear an 1/8" hardened roll pin, while using the z axis, I'm probably doing something wrong. End result, simple, cheap and effective. Not pretty, but entirely functional.

I'll eventually clean up the wiring and a couple other things, but I'm pretty happy with it for now.

 

[davek181]

True, wiper motors are easy to come by and easy to replicate the setup for sure. I will quit stressing about it because as you say shearing a 1/8 pin takes a bit of force and a good mistake.

I like the design, it looks good. I do like the simplicity of it all on display. A person could make covers to hide it all, but why?

I am not sure how fast or slow my motor will be, so the slow feed for boring is still a mystery. Usually a wiper motor has at least two speeds and could conceivably be switched between to change feed rate for slower , or speed up for tool changes while still retaining the variable voltage/speed control on both speeds.

Unfortunately the motor I have in hand is a CAN controlled unit with only one speed I can see and all other functions of speed, park, intermittent are regulated by a control module in the car, which might be a good thing as the motor would be designed to be variable speed.

Other motors if need be are readily available in old school 2 or even three speed models. I think I have a spare Chevy wiper motor for my tow truck that would have speeds and tons of power if I need to go that route. Also the simplicity of this design could easily be offset to the side and an addition of a 1:2 belt drive would slow things down if needed without too much more fabrication.

I will see what I end up with. Probably I will just steal your design verbatim and be done with it, but you know how these projects go.

 

[davek181]

I got mine done, well at least functioning well, you know the projects are never fully done as you think of modifications and things you should have done in the first place.

I mostly copied your concept but lightened it up a little mostly due to what I had on hand. The entire project was built from scrap or salvage except for the power supply and speed controller and lovejoy coupling.

I used 13mm hex aluminum stock for the drive and used a cheapie deep socket for the sliding sleeve. I cut the drive end off the socket and bored the inside where the hex wasn't so it would slide on the shaft well. Rather than the magnet to hold the sleeve disengaged I drilled the shaft and installed a spring and small ball to provide friction to hold it in place. It was simpler than the magnet idea and I didn't have any on hand anyway, but I do have small ball bearing balls and gutted a pen to get the spring .

The lovejoy coupling was an Amazon buy for $14.49. It has a 14mm and 10mm hole on each end and is slotted with a pinch screw on each end. I threaded the 14mm side to screw on top of the shaft on the mill and tightened the pinch bold to lock it in place. The other end I cut the hex shaft down on the lathe to snugly fit in the 10mm side and locked it with the pinch bolt too.

I made a plate to mount the motor on and used 3/8 rod salvage to make the standoffs to hold it. I also discovered while playing with the motor hookups that my motor did indeed have two speeds, so I incorporated a switch into the circuit to use both of them.

With the speed controller I can slow the motor to a crawl. I test bored some scrap aluminum and it worked great. The high speed up and down that I am sure will be used a lot for tool changes and setups is just a little slower than I can crank it by hand, but I don't even have to get off my stool and reach up to raise and lower the head. So it is actually faster to use because there is no wasted motion standing up, cranking, looking to see where the head is, cranking some more, etc. I can merely sit there and watch it or get the tool change ready while the head is moving on it's own.

All in all a very excellent design, thank you for showing us and inspiring me to copy. I have ordered a limit switch that I will incorporate into the mix soon. I will only limit the top because the bottom is too variable due to different setups and I figure I will be watching the descent closely.

 

[davek181]

Here are pics of my install. Very similar but different. I used it a little today on a quick project with a couple tool changes and I already wonder how I did without. While making the faceplate for the switches and display this weekend I was wishing it was operable then.

Still a little cleanup and and wire routing to do, but that will get done with the limit switch install.

 

[davek181]

I installed a limit switch on the top travel just in case. It was pretty easy to do, just made a bracket to hold it and wired it in. It works great and is adjustable to a point but that is not so important way up there on the column. I just wanted it to stop before the mechanical stop caused it to strip or break something.

I figured I didn't need one at the bottom since that value is variable depending on what is mounted on the table, but knowing me I will probably make one eventually anyway. If I do I will probably make it quick adjustable like the Quill stop to accommodate the setup of the day.

I can't believe how much I use this now that it is there and functional.

 

[acruxksa]

I installed a limit switch on the top travel just in case. It was pretty easy to do, just made a bracket to hold it and wired it in. It works great and is adjustable to a point but that is not so important way up there on the column. I just wanted it to stop before the mechanical stop caused it to strip or break something.

I figured I didn't need one at the bottom since that value is variable depending on what is mounted on the table, but knowing me I will probably make one eventually anyway. If I do I will probably make it quick adjustable like the Quill stop to accommodate the setup of the day.

I can't believe how much I use this now that it is there and functional.

I like it am very intrigued about the spring and ball detent, great idea! I hope it works well for you and welcome any and every addition/change that makes it better.

 

[davek181]

After quite a bit of use I have found the spring and ball to be all I need. I don't call it a detent because I did not make a divot or groove for it to lock into, although I considered it in initial design. I was going to take the boring bar and cut a groove if I felt I needed one. As it turned out, just the friction from the ball inside the sleeve was enough to get the job done. There is also an option for a stronger spring, but I like it just how it is.

Actually in use I find that I rarely disengage the the drive and rely on the motor for movement. It is just too easy to raise and lower the head with the motor, and the variable drive adds quite a bit of control as you near the work.

Excellent design idea I stole, and recommend others steal it too, and maybe make more improvements as they work out how to build their own.

 

[Winegrower]

Actually in use I find that I rarely disengage the the drive and rely on the motor for movement

Yes. Regarding handwheels on the Z-axis: When I added an Align type drive to my Bridgeport clone, I made a round handwheel that is permanently attached...can't hurt me when I forget to remove the crank (which I did an embarrassing number of times). But, in use, I find that it's very easy to turn the speed control down to zero, put the handle in the up or down direction, and slowly increase speed to move exactly to the mark intended. It's easy to hit a 0.001 tic mark this way, and if you overshoot a bit, just back off and redo. So I don't really use the handwheel, is my point.

 

[davek181]

My handwheel is far from anywhere I would be otherwise, up near the top of the mill and a bit of a stretch to get at, so I left it intact just in case. I find the power feed much easier to watch because I can sit on my stool and run it. With the handwheel so high you would have to stand to reach it, crank it some, stop look where you are at, repeat.

I often just get real close with the coarse Z feed and use the slow feed on the quill from there which has a DRO scale on it too, unless boring. I don't often need the extra accuracy of having the quill locked and only use the Z movement.