# Power head for my G0704 - not CNC



## wallyw (Oct 19, 2013)

Just took delivery on a G0704.  No intention of CNCing this machine.  Can anyone recommend a motor setup to give me at least a rapid advance.  A slow down feed for boring and threading would be a plus.

Wally


----------



## SEK_22Hornet (Oct 20, 2013)

I think that you will like your G0704 - however, I suggest that you order a couple spare gears #209 in the parts list). They are $10 each and sooner or later I'll bet you strip one.  The first one I stripped is when something I had in the vise was not as secure as i thought and flipped up into the cutter.  It took 8 months to get the replacement gear. Last I knew, they had some in stock - I just got 2 more spares. I am in the process of making a belt drive for mine right now to eliminate that and get a little higher RPM out of the mill.  I'll post some photos of what I'm doing shortly. As to power cross feed - I believe they sell one for this mil, if i remember correctly (haven't looked for a while).  I have an old DC Satellite positioner or two from the big 10' dishes that I'm thinking about using to build a power cross feed some day, and a VonWeiss DC gear motor that I thought might work for the Z axis lift motor. I need to get a couple DC motor drives from ebay to play with on these motors


----------



## SEK_22Hornet (Oct 23, 2013)

I was looking at All Electronics web site and noticed a couple of motors that might be interesting to try for power feeds.  The have right and left hand power window motors and a couple right angle gear motors from power seats (right and left).  All are under $20 each and new.  The power window motors are rated at 3.5 amps while the seat motors are rated 1.8 amps.

http://www.allelectronics.com/make-a-store/category/400/Motors/1.html

Dan


----------



## kizmit99 (Apr 1, 2014)

So, I'm curious whether anything ever came of this?

I'm starting to think that a power-lift for my G0704 mill head may be a nice project.  I'm not interested in going CNC, just something to keep from having to crank the Z-axis handle when raising and lowering the head.  The power-window motors that Dan pointed out look like an interesting option...
I'm guessing that they seem like they would operate at about the desired RPM (about the speed I would turn the handle by hand).
I assume, based on their intended use, they must run forward and reverse.
I wonder if they would have enough power though?
And then the big thing, how to actually mount one so it could drive the existing crank shaft?

I did some searching online and couldn't find much of anything dealing with a conversion like this that didn't involved replacing the whole lift assembly and driving the lead screw directly... (of course, maybe my google-foo is just off)...

Anyone have any suggestions?


----------



## wrmiller (Apr 1, 2014)

I too have no desire to CNC, but would like some assist with the z-axis. 

I am thinking of putting a stepper motor on the z-axis and control it with a stepper motor pulse generator that I either build or buy (check ebay). I want to be able to disengage the stepper motor so I can do fine positional movements manually, then reengage the stepper (probably with a lever assy of some sort) for large movements like tool changes.

If I get really ambitious, I'm thinking of converting the z-axis to a 3/4" or 1" ballscrew to get rid of the excess backlash. I'm thinking the larger screw will reduce/prevent flex in the screw as it's floating on one end?

Or I may just counterweight the head with 50lbs or so of iron and stay with the manual handwheel.  

Bill


----------



## mattthemuppet2 (Apr 2, 2014)

a power window motor (or cordless drill) should be more than powerful enough. The window motor would be especially useful as most already have the 90deg power take off as standard, so theoretically all you'd need to do is made a splined or hex hole in the output cog and slip that over the head crank handle shaft. I'm waving my hands around as I've never seen your mill in person  Then a 12V off an old computer power supply or even a laptop charger brick if it has a high enough output, a double pole switch from radioshack and you're in business. If you can get the crank shaft to go through the motor cog, you could even reattach the hand crank and use that for when you want to go old school.


----------



## John Hasler (Apr 2, 2014)

wrmiller19 said:


> I too have no desire to CNC, but would like some assist with the z-axis.
> 
> I am thinking of putting a stepper motor on the z-axis and control it with a stepper motor pulse generator that I either build or buy (check ebay). I want to be able to disengage the stepper motor so I can do fine positional movements manually, then reengage the stepper (probably with a lever assy of some sort) for large movements like tool changes.
> 
> ...



My Avey is counterweighted.  Works fine and can reduce backlash.  It has a clever adjustment mechanism that allows me to change the balance without changing weights.


----------



## outsider347 (Apr 2, 2014)

John Hasler said:


> My Avey is counterweighted.  Works fine and can reduce backlash.  It has a clever adjustment mechanism that allows me to change the balance without changing weights.




pictures would be great!


----------



## wrmiller (Apr 2, 2014)

John Hasler said:


> My Avey is counterweighted.  Works fine and can reduce backlash.  It has a clever adjustment mechanism that allows me to change the balance without changing weights.



Are you moving the fulcrum/pivot point to change the balance?

I too would be interested in seeing this.

Bill


----------



## John Hasler (Apr 2, 2014)

Avey counterweight photos:





The star wheel on the diagonal part connecting the two chains moves the connection point of the upper chain, altering the balance.


----------



## wrmiller (Apr 2, 2014)

Thank you! That is an interesting method of compounding mechanical leverage. I've not seen anything like it!

Bill


----------



## John Hasler (Apr 2, 2014)

wrmiller19 said:


> Thank you! That is an interesting method of compounding mechanical leverage. I've not seen anything like it!
> 
> Bill



Subject to a long-expired patent, no doubt.

Note that the casting that carries the spindle is on dovetail slides on the column: that is what most of the counterweight is for.


----------



## wrmiller (Apr 2, 2014)

John Hasler said:


> Subject to a long-expired patent, no doubt.
> 
> Note that the casting that carries the spindle is on dovetail slides on the column: that is what most of the counterweight is for.



I saw that. An interesting design. Thanks for sharing!  

Bill


----------



## kizmit99 (Apr 2, 2014)

mattthemuppet said:


> a power window motor (or cordless drill) should be more than powerful enough. The window motor would be especially useful as most already have the 90deg power take off as standard, so theoretically all you'd need to do is made a splined or hex hole in the output cog and slip that over the head crank handle shaft. I'm waving my hands around as I've never seen your mill in person  Then a 12V off an old computer power supply or even a laptop charger brick if it has a high enough output, a double pole switch from radioshack and you're in business. If you can get the crank shaft to go through the motor cog, you could even reattach the hand crank and use that for when you want to go old school.



I'll have to get one of these on order and see what I can do with it...



It's hard to tell from the photo whether the output gear is metal or plastic and it doesn't look like keeping the existing crank would be an option;  but they're cheap enough to be worth giving it a shot...


----------



## mattthemuppet2 (Apr 3, 2014)

neat! I'm sure that once you have it in your hands it will be easier to figure out how you can make it work. Let us know how it goes.


----------



## kd4gij (Apr 3, 2014)

I will be watching to see how you make out. I would also like to have power feed on the head.


----------



## kizmit99 (Apr 3, 2014)

Order placed...
I was doing some timing on how quickly I crank the handle and at 88 RPM this motor may be a bit slower than I would like.  Once it shows up and I verify it has enough umph to lift the head, I may see if I can gear it back up a bit to increase the speed...
I'll report back when there's something interesting to report, but fair warning I tend to drag out projects so it may take quite a while...


----------



## kizmit99 (Apr 13, 2014)

Well - bad news to report...
Once I received the motor and applied 12V to it, I realized that the 88RPM output was going to be too slow.  I was thinking maybe I could use a cogged belt and pulleys to step it back up 2x or 3x in speed (with a matching drop in torque).  I machined an adapter to replace the plastic splined 'gear' on the motor with something I could attach a pulley to:



Then tried my first attempt at broaching (on my lathe) to create a keyway in a shaft collar to replace the crank handle.  As a first test I made a simple adapter to connect those two together so I could estimate whether the motor would have enough torque to handle a 2x or 3x reduction and still drive the shaft:



Then I gave it a try:



Unfortunately, the window lift motor doesn't have enough power to drive the shaft at all (either up or down). This was being driven from a 12Amp 12V bench supply, so I'm pretty sure that lack of input power wasn't the issue.  This was disappointing, because with the built in worm gear it seemed like this motor should have been strong enough to do what I needed.  Of course, without any specs it was all just guessing anyway...

For my next attempt I had read some folks suggesting the motors from cordless drills.  I just happened to buy two at a hamfest last weekend for $3, so I gave one of those a try...



Similar results - not enough power from motor to lift the head.  The drill motor did have enough power to lower it though.

So, anyway, it seems it's back to drawing board.  I know that "Hoss" (g0704.com) was able to drive the stock z-axis lead screw from the top (vice through the crank handle gear) with a 570 oz/in stepper motor, but going with stepper motors and controllers is a bit more than I'm willing to do for this upgrade.  It's not like cranking the handle is all that hard - I just thought it sounded like it would be a fun, cheap, simple mod... oh well...

I'll probably try the window motor on the x-axis shaft, just to see whether it has enough power to drive that -- that'll be academic though, because I already have a Grizzly power drive for that axis.  But maybe that info will help someone else out in the future...


----------



## SEK_22Hornet (Apr 13, 2014)

Sorry to hear that it didn't work - sure seemed like it might. I know most of the drives I've seen do away with the gear at the top and drive the lead screw direct, so maybe that is a clue.


----------



## mattthemuppet2 (Apr 14, 2014)

likewise, I thought that it would work  Well, at least you gave it a shot. Do you have a rough idea how much the head weighs? That might give folks an idea what sort of head/ table weights these motors can handle.


----------



## wrmiller (Apr 14, 2014)

I remember someone saying the head assy weighs about 60 lbs or so, and having carried it I would say that's close. But not officially verified with a scale or anything...

Bill


----------



## kizmit99 (Apr 16, 2014)

I did a little more playing with the  power window motor this evening...

It seems to have plenty of power for using it as a x-axis drive.  Still a little slower than I would be happy with at 12v.  If you crank the voltage up, the RPMs increase as well, and at 20v it moved the table at a reasonable clip.  No clue how long it would last being used that way though.  Since it doesn't seem to be struggling I suspect it could be run at 12v and geared up and still have plenty of torque to operate on that axis.

I then decided to give it another shot at the z-axis handle.  Pushing the drive voltage to 16v and the current to about 6 amps, the motor actually does have enough torque to both raise and lower the head, but just barely.  Also, the motor heats up pretty quickly, not terribly hot, but hot enough that I wouldn't trust it to last very long.  And even over driving it like that, the speed isn't quite acceptable.

I've got a 1/2HP old garage door opening that I'm certain would be plenty powerful enough.  I've seen where at least one guy managed to hook one up to drive his z-axis and it seemed very successful.  His mill was larger than the G0704 though and had a reasonable place on top of the column to mount it.  I suspect it would be very out-of-place on the top of this mill's column...

I'm considering trying a wiper motor if I can source one cheaply enough (read: free).  I've read that some don't like running in reverse, so that could be a concern with that approach...


----------



## kd4gij (Apr 17, 2014)

A seat motor might have more torque.


----------



## outsider347 (Apr 18, 2014)

How about a wiper motor off of a lite truck?


----------



## kizmit99 (Apr 19, 2014)

From some of the research I've done it seems that wiper motors are pretty much built to run in one direction only.  They may run in reverse, but apparently they use a special brush configuration that may make them less efficient and cause them to wear out quickly.  If I tripped over one, I would give it a try though.  

I'm beginning to think that this may be one of those projects where just buying the right parts up front would be the cheapest solution.  Hoss (of g0704.com fame) has shown that a 570 oz/in stepper is powerful enough to drive the factory z-axis screw, and those can be had for $50.  If that was it, I would just go with that - but you also need a stepper controller.  From what I can tell, that costs about another $100.  Even then I'm not sure that doesn't also require something to be the "brains" to control.

I'm gonna give the motors I've got a try at driving the lead screw from above (instead of from the handle) and see if that doesn't increase efficiency enough to make them practical...


----------

