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Pillar Drill Modding

I have been in the process of renovating a pillar drill for a while now (PhD work kept getting in the way). I thought I would share some of this drill press jazz. After drilling and tapping innumerable holes in thick steel by hand (all be it a Bosch powered hand;) while I was engrossed in the wood lathe project, I can see the value of a pillar drill.  This would have been soooo useful, it seems ironic that I am doing this now.

The original Meddings Drill Pressoriginal drill

The idea was that by getting a second hand three phase drill, it is possible to get a really high quality and functional machine, if you are willing and able to convert it to run off single phase electricity supply. Three phase drills tend to be better quality machines suited to industrial use. Unlike a lot of the modern drill presses that are imported you can get a really solid piece of kit.

I picked up a Meddings bench-top M4 Drill Press off e-bay (it was being sold from a school DT department).

I did use the drill in this state, to drill holes in my PhD thesis.  No, I had not gone completely mad, they were careful and considered holes, needed to bind the finished work together (I thought it fitting that I make my own binding after 4 years of research and writing).  To use it like this I made it ‘Sam powered’ – that is, I got Sam to stand on a stool and spin the pulley with gloved hands, while I operated the press mechanism.

Out with the three phase electrics.pillar drill electrics

As you can see a fair bit of paint has come off round the edges of the table and the coolant trough, which we will fix up later.  First to sort out the holes left from accidental and over keen drilling.  I have filled some of them already with JB Weld – it is good and solid and can be sanded flush to the table when dry. Also notice the rust still on the right of the table, which would mark and stain some work pieces.  As long as it is not too terrible it can be removed with some light abrasion and a bit of time spent rubbing.movable drill table

Mixing up the JB WeldMixing the JB Weld

One test hole filled with JB Weld and ready for sanding down flat.JB Weld filling

A close up on some of the table repairs.  Seems to work well enough – a little air hole in one bit but nothing major.part filled

Not being able to rely on Sam to be at beck and call of the drill at all times, I had to sort the motor.  Originally my plan was to convert the three phase motor, and make it a capacitor run type (There is an excellent description and instructions for such conversions in Jim Cox’s book on electric motors – it is a tad old, but a classic). Anyway, after some poking around I discovered that the original motor only had three connections rather than the usual six.  This made any conversion a whole lot more complicated, requiring a whole lot of re-winding of the copper coils.  I already had in mind an alternative though…

The ‘new’ scavenged treadmill motor I have had knocking about for some time is mounted up. Here you can see its credentials: 1.8 Horse Power continuous duty (Not bad!), 4800 revs per min.  More than ample for this application.  The real bonus is the speed controller that comes with it, which is capable of putting out tremendous torque at consistent low speeds.   New motor rating

Here it is after a spot of matching green hammerite paint. Ok, so I do need to stick the rating plate corners down, they look terrible. new motor and paint

Here is the new speed adjustment dial (in the middle of the pic).  It is just a good quality variable resistor taken from a scrapped radio.  drill speed control

Most treadmill speed control boards have an arrangement in which the speed is adjusted by a separate complex computer unit.  Luckily for us though the output from the computer is usually simply a certain resistance, so that we can substitute the computer, with all its elaborate exercise programmes and training systems, with a simple potentiometer.

The treadmill speed control board still retains its nice ‘gentle start’ features, and excellent speed regulation properties.  As you can see I have managed to retain most of the switch gear, that is, the well designed start and stop buttons and the contactors that go with them.

I have started making some hold down clamps using the drill, which is exciting. Will post soon..

Responses to Pillar Drill Modding

  1. Rob

    Good work!
    Im in the process of refurbing an old Meddings too,
    Was that treadmill motor easy to mount or did you have to make up a bracket mount?

  2. Bongo

    Hi Rob. No not too difficult. The grey painted bit you can see was the mount used in the treadmill, so I had that off with a little angle grinding. It fits the motor nicely, as you would expect, and I just bolted that to the pivoting spring loaded mounting plate of the Meddings. Drilling a few new holes was all that was needed.

  3. Paul

    Nice mod. I’ve passed on getting a few treadmills for their bits and motors because of circumstances and I regret it today. They can be handy.

  4. Bongo

    Thanks! Oh my, you passed on a treadmill motor :-O
    They certainly are always worth getting. If you come across one in the future and don’t need it, get in touch – we are always needing that kind of thing for projects ;)

  5. Dave

    It is a little late for this project but just to make people aware, three phase variable frequency drives make these sorts of conversions much easier. Yeah you need to buy a drive, but this is often cheaper or easier than modifying a bunch of parts.

    What I’m getting at is that seeing a machine with a smallish three phase motor shouldn’t turn people off to buying it if the price is right. There are many options to getting the unit powered back up.

  6. Adam

    Hi Bongo, I wonder if you could tell me how you mixed and matched the hammerite green paint as they only do dark green nowadays.

  7. Bongo

    Hi Adam,
    Thanks for the comment. When I was doing it – some time ago, they just had the correct colour I needed in the hardware store. Sorry that’s not very helpful I know.

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