Whats going on with this drill?

Yes you could convert it to double insulated. Not easy though.

You need to put it an insulated housing so that in use you cannot touch any part of its metalwork. It will be quite difficult to actually use it, unless you make an extension shaft (out of insulating material) that passes through the housing wall so that the chuck is on the outside. You will also need to make an insulated extension to the trigger switch.

Good news bit is that you only need a two core cable!

Or you could wear thick rubber gloves while using it.!

Seriously though most older stuff will sail through a pat test if properly maintained, the only thing thay will need replacing is what looks like rubber cable.

Oh my good lord it is absolutely massive, must have originated in a ship builders or something.

Also is this an american plug? Screws into the body. Considering it has AC universal on the name plate I am wondering if this is designed to work with a wide range of voltages.

Edited By Rainbows on 09/05/2015 11:30:46

"Universal" usually refers to a motor capable of being used on ac and on dc. It doesn't mean it will work on a wide range of voltages.

Russell.

I used drills like this while serving my apprenticeship as an electrical engineer in the early seventies. here are the ups and downs.

They are very powerfull, slow and low geared, which means they will quite happily twist the operator round if the drill bit stops!

They are incredibly heavy, tiring to use, but the weight means it will drill a hole without having to push very hard.

They need an experienced and strong user who is not afraid of the thing!

They are all metal, and despite what has been said above, virtually impossible to double insulate, so they must be earthed, although the 110v transforer does, as also mentioned above, reduce the shock voltage to 55v, I would also use this tool with a RCD type trip if at all possible.

Having said all that they are built like tanks, and are virtually bulletproof, due to the fact that it virtually impossible to overload the motor, due to the gearing.

I would fit a proper 110v plug to it, Check the carbon brushes, check the continuity of earthing all the way to the case of the tool, do a megger or PAT test at 500v to check the insulation WITH THE TRIGGER SWITCH IN THE ON POSITION, and if all is ok, test it on the transformer. These drills do very well when fitted into a stand and used as a pillar drill, but with the price of power tools today, they are precious little use for anything else, although there is probably enough aluminium in the case to build a jumbo jet!

Phil

Hi Phil,
If the drill is used with a transformer with the centre tap of the secondary earthed or a floating secondary an RCD on the primary will provide no protection. (Unless the transformer develops a short between the primary and secondary windings.)

Les.

Edited By Les Jones 1 on 09/05/2015 18:05:04

Well the insides all look good, had to scrape a mix of dust and grease off the inside and added some new grease but that was it.

The power cable is funked. The plug was cracked and the cable insulation split. The connecter to the drill however is fine and I worked out where earth goes.

Gonna have to say I have never done a PAT test. What would it involve?

Hi Rainbows, a full PAT test would involve buying a piece of kit that would cost you more than getting a local trader to do one for you. Have a look at this **LINK** to get some understanding of the procedure.

Regards Nick.

Hi Phil, I agree with Les about an RCD, and assuming one uses a proper good quality (PAT tested also if need be) yellow site transformer, it is very unlikely to short between the primary and the secondary. An earth is a must though to prevent being potentially exposed to more than 55 volts which is said to be the safest limit for the majority of people and it is unlikely for anyone to be electrocuted at this level.

Regards Nick.

Having chatted to Nick today, I'm not sure he is the best person to advise on health and safety issues

Neil

Les and Nic, you are both correct, I meant some sort of rcd betwixt transformer and tool, if such an animal could be procured, and the reason I said it is that although 55v is adjudged to be "safe" I well remember nearly falling of a ladder some 25 feet in the air after getting a shock from a control circuit on a silo level indicator, which was working at 24v! The shock you percieve is dependant on how well you are earthed, and not entirely on the voltage present. I percieved a much greater effect because, as someone who never liked being up ladders, I was hanging on to the grain silo with sweaty palms. I am not entirely sure, but is there a trip on the transformer, or do you just carry on getting a 55v shock till you put the tool down, as these drills, being low geared , take a long time to stop. Most 110v site equipment is also double insulated, whereas this drill is not, so even with a safety transformer,in the event of an insulation failure in the drill, the case would become "live" with respect to earth @55v, whereas with normal Double insulated site equipment you have to really push the envelope to create a dangerous situation. "Oh, this drills getting hot! I'll dip it in this handy bucket of water to cool it down" (Don't try this ANYWHERE!)

Phil

Hi, all I can say is try not to fall into the river while working, at least not in February, but I did manage to rescue my hard hat after it got washed off my head.

Regards Nick.

Hi Phil & Nick,
My feeling is that a floating secondary on the transformer is the safest provided the transformer is well designed to ensure that there could not be a short to the primary side. These drills also scared me when working up a ladder.

Les.

I rather suspect that the comments about converting it to double insulated were intended to be facetious, if not then they should have been. There are standards to meet for double insulation and meeting them would cost more than the drill is worth. However, if used as has been suggested, with a double wound transformer with a centre tapped secondary it should be very safe,especially if the case of the drill is also earthed to the same place as the centre tap. The two power connections of the drill should be fused if this is how it is connected. This ensures that if the power connection shorts to the case, the fuse will blow, removing the supply.

Although 55V has usually been regarded as safe, I have heard that people have died from Voltages as low as 12. It all depends on the situation, especially the skin resistance, which can vary a lot.

I'm actually not all that convinced about double insulation, I rather suspect that the objective was to save a bit of money at the manufacturing end. It is supposed to ensure that there is always at least two layers of insulation between any live part and the user. That is fine until water gets in, so I would not use a double insulated device anywhere wet or outside without an isolating transformer or RCD.

On the other hand, the older arrangement with the outside metalwork earthed means that the safety depends on a passive wire, eg there is no easy way of telling that the earth wire is broken, and the break could be anywhere between the appliance and the house earth. The appliance will still work. So the user is safe unless at least two faults occur, but there is no easy indication that the first fault has happened.

John

Inherited my Dad's Millers Falls old machine.

Saw him on a number of occasions being spun round when the drill bit jammed as it broke through, no injury, just lots of words I hadn't heard of then, but now use when appropriate

Geoff - Waiting for 'Management' to wake after night shift.

Both mine and Lofty's replies were tongue in cheek, I never thought that anybody would even contemplate thinking about converting to double insulated!

Regarding 110 Volt powered hand tools and site equipment, nobody has ever satisfactorily explained to me why having a grounded centre tapped secondary is safer than having the winding floating.

There are too many possible fault combinations to go into here but with the 55-0-55 method some faults could result in the casing becoming 'live' (at 55 Volts). Whilst it may not be lethal, if it did come into contact with an earthed object, say through the metal strap of a watch it could put a nasty burn on a wrist. With a floating secondary no current would have flowed so eliminating that risk and any chance of sparks etc.

As far as I know ground fault detectors and earth leakage trips are not fitted to the low voltage side of any isolating transformer so it seems to me that a floating 110V supply would be the safest technique.

Ian P

Considering mine uses 4 amps rather than 1.5 amps I better not let it get jammed or bits of my arms will be flying over the horizon.

Also I might of arranged to buy a 5.75A, 1" Wolf Heavy Duty drill. Which will be even bigger and heavier. Apparently I just hate having my various arm bones being in their proper places that much. Having 900 and 380 RPM drills sounded like a good idea. Also the wolf has been used till recently so I have less electrical worries.

Drilled big holes with a windy drill in the past, a bit hairy up on scaffolding. Usual thing was to rig up some sort of rope sling to help retain the side arm. Might be useful for the electric ones.

Oops, 230v.

280v should have rung alarm bells as being rather odd, but I didn't think anything of it.

Geoff - Note to self 'THINK, THINK, THINK!". Feather and chicken.

Trying to not get off topic but what on earth was a dril this big needed for? It has a drill press stand but I can't fathom the point where you would need to unhook it and risk your life trying to use it by hand.

SWMBO is already trying to make me get rid of it, my only hope is to bolt its stand down into concrete before the next auction sale.