Power Feed to Milling Machine Table

I have a Warco Minor Mill/Drill having owned it for some years and it has served quite well. However I really need to fit an X axis power feed as winding handles back and forth is quite tiring. I see the Warco ready made power feed unit is some £350 which is more than half the price I paid for the machine and does not appear to me at any rate particularly good value. I have seen on You Tube the system built by Stefan Gotteswinter which is quite good but also quite complicated. However as a result I now have acquired a wiper motor and am ready to design and build my own version.

Before i start I wonder if any of the Forum members can recommend any alternatives from build your own to buying a reasonably priced manufactured unit.

This is my first post so hoping for positive replies.

Jonathan

Probably the simplest is a battery drill whose rechargeable pack has died (often available at jumble sales) with bench psu and simple coupling to handwheel. This is how I get lathe power crossfeed. You still have to stand there with it but you should anyway.

Hi, I started making a power feed for my warco wm14 mill using a 24 volt truck wiper motor I had. After making a nice power supply with adjustable voltage, limit switches etc mounted the motor onto the mill and it was a bit slow, and the power supply could make it go even slower, so a waste of time and money. I would say try the motor first just to see what revs it does before you spend lots of time on fancy controls like I did. I will get round to trying another motor sometime but as of now I use a battery screwdriver which I bought from B & Q for £ 10.00 which has forward and reverse gears and it works very well. you can just unplug it from the lead screw to give full manual control. One of the problems I had with the first system is disengaging the drive from the wiper motor to give manual control back. have a look on you tube at warco mill drives and you will see one my brother did on the same mill using an old 9 volt battery drill which works well with machano bevel gears which can be disengaged.

Well Jonathon - first welcome to the fray!

I have a Warco mill/ drill with a power feed to the table and it is a great asset. ....... however I'm afraid I took the easy route and bought the power feed unit. So I have proved to myself that it IS a useful facility - but at a price ! If you can't get one via the birthday / Xmas route then I think the battery drill option sounds promising.

Norman

I have power feed on my Rexon mill, using a windscreen wiper motor. I extended the shaft on the worm wheel to take a 10 tooth sprocket to take a bit of bike chain, and it drives the lead screw with a 20 tooth sprocket. At the moment(and for a good many years) speed is adjusted with resistors, so only three speed. The chain is loose on the sprockets, so easy to lift off for manual operation. It took an afternoon to build, including making the 10 tooth sprocket, I had a 20 T one.

Ian S C

I found one at Axminster in their machinery sale each year for about £150 and an easy mod with help from here made my WM18 soooo much ncer to use.

Martin

I made a power feed to my Naerok RDM 350 table top mill using an up down window motor. Unlike some wind screen wiper motor these are designed to go forward and reverse. I made a dog clutch so that I can wind from one end. The power supply is a 12 volt transformer rectifier NO smoothing as I used an ex washing machine Thyristor which requires rough DC. I have a variable resistor for speed control and a double pole change over switch for For/Rev, nearly forgot push button for fast traverse The small gears were ex photo copier.Took me a while to get every thing married together, cost wise maybe £1. That was 20 or more years ago.John

I used a 24V window winder from a surplus shop and a variable 0-30V PSU similar to this. Together with a simple changeover switch (DPDT) this allows variable speed in both directions.

3A at 24V is about 75W ie plenty of power for a mill/drill. Not sure what you'd do with 20A (almost 2/3 HP!!).

I couldn't be bothered to come up with anything fancy like a clutch, so instead I used a wingnut to enable me to fit or remove the thing quickly - takes seconds. As it already has a sort of dog clutch connection between the handwheel and the leadscrew, this is a simple and effective solution.

Funny this should come up. Although I no longer have the machine, I came across it yesterday when moving stuff about.

Photos in my album here.

Murray

Out of curiosity, what sort of speed ranges do people find useful?

Neil

What I have bolted onto the X3 at them moment will only go down to about 100mm/min but could really do with about half that at times. Goes upto about 700mm/min which makes a nice fast return at teh twist of a knob.

I'm not certain about mine. I suppose I could measure it if life depended upon it. From memory the min speed was perhaps as little as several seconds per turn With a 2.5mm pitch(?) that would mean perhaps 60mm / min for the finest feeds or around 2 IPM in old money. And IIRC, the "rapid" speed was something like 100rpm at the handle, which would be around 250mm / min or 10 IPM.

Hence a fully variable PSU which I would strongly recommend. The Tenma one I linked to is also very handy for other purposes. Pretty amazing deal for under £50.

Whats the torque like on the wiper/window motors as you slow them down, I can run slower but only for very light cuts.

I thought I had made a post in this thread mainly due to the mention of 24v wiper motors as I feel that they should do this sort of thing pretty easily.

I want to do something similar using one. I'd be looking for a least a 10 amp supply. I mentioned that there are some very well prices 24v 500w supplies on ebay at the moment. I have one on order. If overloaded the voltage output of this type will just drop to next to nothing for short circuit protection so too many amps available should help.

For speed control I will use the same sort of controller that electric loco's tend to use that have feed back from the switching element which helps keep the speed constant. i'll probably find that a supply like this would benefit from fairly hefty smoothing via capacitors when it's loaded like this so will use several in parallel which will also help get round ripple current problems without spending much money.

If I go on to use the same supply for a power feed fwd/rev/neutral would be via the same sort of arrangement as a lathe tumbler reverse uses.

In both cases I shall measure the motor rpm and add gearing as needed. As my miller is pretty light weight I reckon something possibly a bit above one rev of the handle per sec would do for a fast feed. Easy enough to do some milling and find out.

In my case I don't think that the supply Muzzer uses would cope with how I set the slides. Good point about being useful for other things. I bought a quad output one that has a bit more power a long time ago - good job too as the prices have rocketed. I don't think people trusted far east sources of things like this when I bought it but I found some good reports on the web.

John

-

My home made power feed uses a 12 volt car seat motor which has plenty of torque but is too slow. It runs at 43 rpm which translates to a feed of 4 inches / 110mm a minute so I don't need a speed control. It does produce a a very good finish and as a friend said to me 'at least with a slow speed you can take deeper cuts'! I did build in a dog clutch so I can disengage the motor when I want manual operation.

I intend to change the motor to one something like this one on e-bay 272239799531, when I've got time!

Maintaining the torque when reducing the speed shouldn't be a problem if a PWM (Pulse Width Modulator) is used as the speed controller.

You can work out the speed of travel that you require in terms of Feed/Tooth.

Figures quoted by an industrial milling machine manufacturer, in the late 1950s for Industrial machines, on low carbon steel, in IMPERIAL units, were:

Face Mill 0.010; Helical Mill (Cylindrical /Slab Mill) 0.008; Slot Drill 0.006; End Mill 0.005; Form Cutters 0.003; Slitting Saws 0.003.

The note with these figure reads "Factors which must be taken into consideration before choice of feed is made are 1) Power available on machine 2) Rigidity of machine and set up 3) Convenient cutter life and accuracy of final dimension"

From personal experience, these figures are valid for heavy and rigid Industrial machines, so for our hobby machines would need to be reduced by a factor of 2 or 3, possibly. A RF25 with a Vertex rotating vice is definitely not the equal of a 3 ton Cincinatti with an Abwood vice on the table.

The required torque can be gauged by feel, or more scientifically using a weights and a torque arm on the traverse spindle, or a torque wrench.

Howard

Doesn't matter if you use a PSU or a PWM controller, the torque is simply a function of the current you push through the motor. So if you can get the amps into it, it will generate the torque even at low speed. The PSU has the advantage that you can set the voltage and the current limit from zero to 100% of rated. Makes it simple and safe. Just an idea....

Table feed rates, according to lathesdotco, for the Centec 2B were 4'' per minute tops.

0.65, 1.19, 2.18 and 4 inches per minute are the figures quoted. Of course, with a VFD fitted, I can choose whatever speed I fancy....

Think about it another way that is used on universal motors at times. They might state 180v motors on the plate but are run from 240v via a controller. That means that the average power feed to the motor can be increased to maintain a constant speed under load. The speed will be what ever it was at 180V over a range of loads. This is the sort of thing they did in mains powered variable speed drills. Either PE or PW published a circuit that did this with ordinary mains electric drills but it could only really regulate speed after it had been reduced.

They are not that precise in practice but a lot better than just powering a motor from a normal supply. I may have some graphs somewhere so I'll see if I can dig them out tomorrow. There will also be one for when an encoder is is used. Same thing applies. There must be more power available to maintain a speed. Other graphs should show speed behaviour with just a normal power supply.

John

-

Edited By Ajohnw on 02/08/2016 23:11:41

I made mine out of a car wiper motor; just had to buy a Chinese PWM on e bay ... 240v input - 12v output... nothing too complicated to set up ... even for me... link to YouTube vid of mine in operation...

**LINK**

George

Feeding too slowly results in cutter rubbing rather than cutting and going blunt very quickly. Tubal Cain's book (Model Engineer's Handbook) has useful table giving cutter speeds and feeds for various cutter diameters and materials.