Not a completed project... as a matter of fact it's just in the "Hmmm, I wonder....." stage. I already have a PC power supply hooked to my mill as an "Accessory supply" (Lights, maybe a coolant pump, power feed etc.)
I finally got to take a closer look, and see what I have that may work for the power feed.
The "doner" is a 12V Ryobi cordless drill. I took it apart and it looks like there's some mighty usefull bits in there. The motor, gear drive and clutch are all one assembly. (Cylindrical, about 1.25 diameter.) I got the chuck off, the output shaft is threaded outside with what looks like maybe a 3/8" regular thread and tapped left hand threads on the inside. I don't know if the threads are metric or Imperial. (Yet)
Mounting it should be dead easy.
Electrically.... some pleasant surprises. I think the motor controller can be hacked. It may take some fancy soldering, but the main circuit board has what is clearly a potentiometer "strip" on the trigger that I'm pretty sure I can isolate and replace with an outboard potentiometer. The Fwd/Rev switch is a seperate unit from the controller and can be easily replaced with a regular triple throw switch.
I will take some pics next time I get to work on it and post them up, along with thoughts and how I manage (*if* I manage) to hack the speed control. I am pleasantly surprised by what I've seen in there... it looks like it may be easy to use not only the powertrain but even the speed controller too! I kind of figured it would be so proprietary there would be no chance of salvaging that part. It's obviously rated for it, and it's nice and small too.
This may end up being something like the $10 powerfeed... since the drill was a toss away.
Consider me prodded... well, a little anyway. My parents are coming in to visit next week, wife has had me cleaning and scrubbing, LOL. Maybe I can really dive in on it after next week.
Anyway... here's a couple of pics to get started. The body of the motor measured 1.45"
It's NOT a resistive trace like I thought it was. It's segmented on one side. Not a deal killer... actually in some ways it may be easier. From what I can see, there are 6 traces, each presumably activate a different speed. So, it won't be infinitley variable but it will have 7 speeds (Including stop, that is.)
I like your switch... I done this a few months ago and mounted the trigger in a box then made a rotary cam that depressed the switch for speed control... your method is much better.
I did not put a reverse on mine, figured that I will never need to reverse feed. It works fine but now I am thinking the reverse might be practical.
I had an electric clutch from an old copy machine, runs on 12 to 24 volts, I use this to turn the feed on and off without touching the speed (trigger in my case). I do have more pictures if interested.
I'm picking this project back up again. Well, starting to anyway.
I gave up on hacking the original controller. I remain convinced it *could* be done the way I intended. I should have taken more care in taking it apart however. Inside the plastic casing were metal clips that connected various points on the board. The problem is they fell out when I cracked the plastic casing open and I wasn't able to figure out where they belonged, LOL.
It works just dandy, and I figured out a way to short the pot so I can use a momentary switch to kick it in to full speed mode. (Rapid). Plenty of torque even at low speeds.
So, here follows the stream-of-consciousness brainstorming session... LOL.
1) Main power... probably one of those "Fighter pilot" flip switches as a pseudo emergency stop.
2) An indicator light... I will forget it is on.
3) Direction. Left/right.
4) Speed dial.
5) Go baby GO! (Rapid)
Hmm, anything else that would be handy?
I'm also debating whether I want the controls on the powerfeed unit, on the mill head or maybe even a pendant? Hmmm... nah, I have enough crap hanging out on my mill bench, pendant would just be something else to get tangled in.
I have an extra table end like goes on the handwheel side. I got it once upon a time to see if I could work the bearing arrangement in to the Y axis. Turns out that wasn't very feasible, but it was only $6 and I got it shipped with some other stuff from Grizzly so the total wasn't much more.
18 P8689018 Y-AXIS BEARING SEAT $6.00
(Although it's really the X axis bearing seat.)
I'm thinking/hoping I can bolt that to the other side of the table as a bushing/mounting block for this thing. If it works out I will probably try drilling 2 hole "pockets" to mount 2 round stock rails in there as a slide for the motor. Then the motor can slide in/out on rails and just engage the split end on the leadscrew. Hmmm, add a spring and a cam and it may really be just that easy? Mounting the motor should be pretty straight forward... it has two screws holding the clutch mechanism in place already. Simply remove and re-assemble after passing the screws through a mounting plate.
Hmm, I will need a solid table stop as well to overcome the clutch... right now the X can just screw off the end of the leadscrew. The table cap may fix that issue, though.... matter of fact Im pretty sure it does.
Finally... Id love to get it to sit flush with, or slightly under the top of the table. That way I can throw something long on there without interference.
OK... stream done... for the moment, LOL.
(Edit.. Not counting what was on hand and and not otherwise being used the total is now: $27
$21 Motor control
$6 DPDT switch
I putzed with the design a bit today. The extra end cap at least helped me realize something.... the leadscrew is offset about 1/8th from the center. So, I could maybe machine the outside surface flat, then flip it over and ount it backwards... but by that time I might as well just go ahead and make a fresh one.
I used a method I have had luck with before, but haven't seen mentioned. I scanned the existing end cap and created a B/W JPG from it. After a bit of cleanup it looks like Pic 1.
Then, I imported the JPG in to Inkscape, which is a freeware vector graphics app. Using the "Trace bitmap" tool I was able to then convert the shape into vector lines and edit them for some cleanup. Once it is a vector graphis it is very easy to scale/tweak/manipulate it. The overall size was way off after tracing, but by simply keeping the hight and width locked to the same ratio I was able to easily scale it back to match exactly.
And example of that is the CleanedUp.pdf. If I print that out from Inkscape I get a dead on 1/1 match of my end cap. Within a few thou for sure. It also is super handy for "curvy things" that are hard to measure. (Well, for me anyway.)
What good will that do ya? Well, now I can layout my part using the inkscape tools. It lets you place down to .0001 and although it's not the most advanced CAD type thing going... it's free and comparatively easy to use.
Now I have the layout... I can print it out as a reference, OR... glue it straight to the stock and work from that. (Depending on required accuracy.)
My untested and NOT reality checked end cap is in the endcap.pdf file.
(Edit... Grrr, not sure why but it thinks there is an inline image... there isn't. Just the 3 attachments. I also just updated the endcap pdf, found a couple of mistakes. there's probably more.. LOL.)
(Edit 2... got it, I had the wrong extension on it.)
Made some progress yesterday... got the mounting plate and the motor mount done. I need to update the plans.. LOL, no plan ever survives contact with the project, does it?
I used 3/8" AL plate, 4" X something. The basic dimensions in the plan were fine, I just made some changes so I could add a flip down lever to keep it disengaged.
So, motor mounting is sorted and so are the slides and the lever mechanism to disengage the leadscrew. That worked pretty well, actually. Now to make the adapter between the leadscrew and the motor, and make up the enclosure for it.
I'm kind of waffling about the best way to make the enclosure. Maybe I will knock up a quick bending brake and just bend it out of some sheet steel. The other idea was to use some angle iron and use that on the 4 corners and just cover the rest with flat plates. As yet undecided.
Here's another "useless" bit of info re the 12 volt motor out of that drill.
The early version of this saw had a 12 volt motor fitted and when you bought the saw you had to buy the step down power pack to go with it. Now being only 12 volt, it soon let out the magic smoke, so for a replacement motor it would have been cheaper to just go and buy a brand new saw.
This is where this motor from the chuck away drill comes into it's own, it's the exact same motor, even got the same numbers stamped on it. A bit of mucking about and bingo, the saws like a bought one again.
I can buy these "second hand thrown away drills" from the recycle centre at the local tip for 5 bucks, good value, eh.