Rebuilding a Meddings Pacera A10 with issues

[DiyAddict]

On to the table arm now. This is bigger and heavier than the drill arm, but at least it doesn't have a pillar attached. Here it is in original cruddy glory:

Here's the view underneath. You can see the repair made to the shattered clamp:

The extra repair bits were screwed on pretty tightly, but I managed to get them off without shearing anything:

Just to recap, this drill has a coat of blue hammer-finish applied reasonably well over the original grey paint, then another coat of green hammer-finish applied by what I can only assume was a very bored apprentice on a Friday afternoon, given the job after he drilled one too many times into the table. When stripping it off the head at the beginning of this thread, I did say that I was just going to smooth the other pieces down with abrasive paper, but they do not sand well at all.

So I've gone back to the paint stripper, especially as I have a 15 year old can of Travis Perkins Nitromoors equivalent that's gone dark brown, but remains potent, so it's not costing me anything. Actually, I've found that this is the most effective method for me and this particular drill. With a bit of practice, it's actually quite easy to get the hammer-finish off while causing minimal damage to the original coat. Here's that work in progress:

Essentially, I splashed it all over for the green coat, then used a smaller brush and was more selective for the blue coat. It took no longer than an hour to get to this stage:

Sorry about all the clutter in these photos. The rest of the blue was easy enough to remove with a battery-powered finishing sander.

Back inside, filled, Kurusted, and sanded:

and two coats of primer:

That's the last post where I'm going to show every stage of prep - I know it all gets a bit samey. But as an addendum, I introduced the repair brackets to a flap-wheel:

Of course I had Steve Darnell over my shoulder urging me to give them a quick polish then a coat of clear-coat. I can feel his opprobrium as I post this next photo:

 

[DiyAddict]

On to the main pillar. This is the last of the major items to require immediate attention. It's been languishing in a damp outbuilding for a while, so I've periodically sprayed it with oil. Here it is at the start:

Took the rack and thrust collar off, degreased, then set about hand-sanding with 400 grit. After rubbing off the worst bits, I cut the wet-and-dry into strips lengthwise and made a couple of wooden clamps to hold either end of the strip to stop my hands cramping up. Then I wrapped the strip around the pillar and sanded as close as I could to match the original machine marks. Then did the same again with 600 grit.

After I got halfway down, I took the pillar out from the cast iron support, turned it upside down, and started from the top again. My back and knees aren't up to doing this sort of work crouched on the floor for extended periods. Once I'd turned it upside down, I couldn't tighten the big retaining bolt as that would mash the newly gleaming surface, so I just screwed the support to the floor to keep the pillar stable. I'm pretty sure I didn't take much material off.

Eight hours later, and the pillar the right way up again:

A thing of beauty in its own right, I think.

 

[DiyAddict]

I want to do a couple of posts on colour, as I've had a hard time choosing and matching colours for these earlier Meddings machines, and I think what I've found may help others in the same boat.

My colour choice has now been made for me by a recent purchase. A few weeks ago, I came across a Meddings MB4 of similar vintage to mine, from a dealer a long way from me. I thought it worth investigating the possibility of buying this machine just for the head, which I could swap for my A10 in case my planned quill/spindle repair didn't work. I could always leave a chuck permanently in my original head, put it on the bench drill, then have a fully specced head on the A10. The machine wasn't bargain-basement money, but it was still very cheap compared to most of the MB4s on Ebay. The dealer assured me it was in great condition. I had him check out the state of the quill, slots and morse taper, which he assured me were all fine. He had his engineers check it out, and they decided to replace all the bearings and oil seal in the gearbox, and he sent me some photos while this work was being done.

I took the plunge, and guess what? It really is in great condition! I hooked it up to a cheap inverter and it runs sweetly. Here it is temporarily on a chest, with an Axminster woodworking fence installed:

Ok, the pulley cover isn't original, but it works well and I'm pretty sure the head has never been repainted, as evidenced by this close-up:

Lovely. So lovely in fact that it seems a crime to split this drill up and put the head on the A10. Actually, it my even be a crime, as I'd have to swap the serial plates around, one of which says ART 10, and the other of which says MB4. Well probably not illegal, but slightly dodgy.

On the other hand my spindle repair may turn out to be pants, in which case I will have to use the MB4's head, so it makes sense to choose the same colour as the MB4. (I could just take the quill from the MB4, but there are a few reasons why that's problematic, which I won't go into here)

 

[DiyAddict]

So what colour did Meddings paint their drills in the 1960's? I did a lot of hunting around and couldn't find anything. I even phoned Meddings themselves and they didn't know. Also, why doesn't the MB4 colour match my A10 colour, which is a lighter shade of grey?

By the way, there was some discussion earlier in this thread as to whether my A10 was originally grey or Meddings Metallic Blue. While stripping paint from the gear lever cover, I came across a definitive answer to this:

Underneath the blue layer emerged the "Do not change gear while machine is in motion" decal. So the A10 was definitely grey originally.

Also, there are a number of parts of my A10 that have never peen repainted, and they are all the same shade of grey as this gear lever cover.

I now have bits from three Meddings drills - my two, plus the gear lever casting generously donated by @brewdexta (from which I've stripped the flaky bright blue paint), and they are all different colours:

Granted, the MB4 cover is only slightly different to the casting, but I've checked against other internal parts of the MB4, and they are definitely not as bright a blue as Brewdexta's casting.

So at the moment, I'm veering towards the opinion that until the 70's, Meddings didn't have a trademark colour, and just used whatever paint they had lying around. That said, A lot of the MB4/MF4s I've seen on Ebay look close in colour to my MB4. It's hard to be sure, but I'd guess the MB4 colour is quite common.

I ordered an A2 colour chart from Paragon, which has all the current RAL, BS4800 and old British Standard (BS381C) colours, and set about finding a match. I couldn't find anything close to the MB4. Here are the nearest ones:

The 4 digit colours are RAL, the 18 B 25 is BS4800, and the named 3 digit colours are BS381C.

There is a Dulux colour closer than any of these - 81BG 12/055 "Winters Sky", but it still doesn't quite match.

Paragon do a range of colours to match old British machines, but they don't have any Meddings ones. However, they've been very helpful, are equally interested to find what colour it was, and have agreed to match my MB4 colour at no extra cost if I send them a part, so it may be possible to purchase this colour from them in the future.

In case Meddings weren't as arbitrary in paint choice as I've speculated, I also attempted to match the lighter grey of my A10. These are the closest colours:

This is the round collar that supports the table, which has never been repainted, and which I've subsequently sanded down so it shouldn't be discoloured by grease etc. The old British Standard BS381C 693 Aircraft Grey is very close indeed. If I'd taken any piece and painted it that colour, I don't think you'd notice the difference.

So, to summarise, and to add other info I've learned for completeness:

If your 60's Meddings is smooth mid grey, try BS381C 693 Aircraft Grey
If your 60's Meddings is smooth dark blue/grey, speak to Paragon (once they've matched my gear lever cover)
If your 70's Meddings is metallic blue, try Rust-Oleum CombiColor Hammertone Light Blue 7321 (from several forums I've been researching)
If you have a modern Meddings (or want to paint yours a modern colour), Meddings told me that their current colour is RAL 5002

But bear in mind that your 60's Meddings may have a different original colour to any of these.

I hope that helps, All the best.

 

[DiyAddict]

Just a quick update - Paragon have now mixed my paint and made it generally available on their website - Machinery workshop colours>Meddings Drill Press Dark Blue Grey.

 

[DiyAddict]

It's been a while since my last post, but I've managed to grab an hour here and there for the A10 restoration. Mostly it's been boring stuff - sanding, filling, preparation - but I've made some progress.

Firstly, here's what I decided re. the bearings in the table lift mechanism. I managed to source an equivalent to the shattered thrust bearing. It's the same thickness (3/8"), but whereas Meddings went for a larger ball race with thin thrust washers, this ball race has much smaller balls and thicker washers:

Arguably Meddings had it wrong, since the original thin thrust washer disintegrated, but looking at the two, I still prefer the original bearing from the cheap pressed steel cage and small balls of the new one. So I've decided to just take one washer from the new bearing and add it to the original parts. This makes the whole bearing very slightly thicker, but it won't affect operation, and I can adjust the thickness of the top hat bush to compensate.


For the top hat bush, I bought an off-the-shelf bronze bearing with built-in oil, and used my mini lathe to make a collar so it resembles the original:

The collar was a nice snug fit on the off-the shelf bearing, so it should work well. Here it is beside the original:

 

[DiyAddict]

The Paragon paint is a good match for my MB4 bench version, but it needs a lot of skill to apply. There's a very narrow envelope between showing all the brush strokes when dry, and runs everywhere. So after one failed attempt at hand-painting, I added 10-15 % Xylene (the only thinner I had), and had a go at spraying. Here's my setup, in the room I'm supposed to be renovating:

On the whole, it worked well - a couple of small runs in places, but much smoother than my brushed attempts:

I love the curves of these old 50's/60's drills - makes them very tactile - so I'm compensating for my lack of skill to make the major pieces as smooth to the touch as possible. It's been a LOT of work, though.

 

[Carl Wilson]

Very nice indeed. I'm using paragon paint on my Harrison Mill. I just brushed it on but I managed to get a good finish. Good enough for me anyway.

 

[DiyAddict]

Starting to feel the end's in sight. When you put so much effort into the major parts, a similar effort is needed for the lesser ones, or they'll irritate me for years to come. I have to decide what to do about the brightwork, for example.

I've taken a tip from Geoffrey Croker on the bolts. If you haven't seen his lathe and drill restorations on YouTube, they're a treat to watch. Anyway, Geoffrey uses Gun Blue as a DIY alternative to having the black parts blacked properly. At the time of writing, we're in lockdown, so I didn't fancy sending the parts off, plus I want to do as much myself as possible, or I won't learn anything (and I'm tight).

So here's a typical bolt in its original state - full of rust, gunk, and Hammerite:

A quick going over with the powered wire brush and degrease, and the bolt looks in pretty good condition. The right hand bolt has some Birchwood Casey Gun Blue applied:

The whole process only takes around five minutes. Ok, it's not as dark as proper Engineering Black, but it has similar protective properties, and looks great in situ:

Same goes for the table lift rack. After some considerable time degreasing, I realised that the the rack was originally blacked, not just gunked up with particularly stubborn oil as I'd originally supposed:

So I sanded off the original black with progressive grades of wet and dry:

I was very tempted to leave it like this (I like shiny shiny), but it wouldn't match the teeth, and I couldn't face the effort required to make them gleam. Plus, Meddings originally blacked it, so I should attempt something similar, so out comes the gun blue again, and a light buff with fine wire wool:

I like this. It still retains a sheen, but offers more protection, and now matches the teeth. Once again, it looks great in situ:

 

[DiyAddict]

Very nice indeed. I'm using paragon paint on my Harrison Mill. I just brushed it on but I managed to get a good finish. Good enough for me anyway.

Thanks Carl. Originally I followed Paragon's advice to the letter, about making sure the ambient temperature was at least 20 degrees, plus good quality brushes etc. But after completing the spraying, I still had a few pieces left to paint, and I found that hand-brushing in a cooler temperature - say 10 degrees - worked much better. As good as the spray gun, in fact. I haven't been particularly fussy about the finish, but my first attempt was just awful.

Having (eventually) achieved a nice finish, I love the Paragon paint. It's good to use something designed for the job, and it looks fantastic. Plus Steve at Paragon has been helpful throughout so it's nice to support a British company in these troubled times.

 

[DiyAddict]

Back to the lifting mechanism. I'm really pleased with the thrust bearing and bush. Here it is with the retaining collar and a new tapered pin. Smooth operation with no discernible play:

Now I have to decide what to do about the handle. Most of the original chrome has worn off and the steel beneath is rusty and pitted:

My current plan is to sand it down with elbow grease to as shiny a finish as I can muster, then electro-plate it with nickel (another of Geoffrey Croker's tips). I have the nickel electrodes and white vinegar ordered. Wish me luck!

 

[slim_boy_fat]

Geoffrey uses Gun Blue as a DIY alternative to having the black parts blacked properly.

@The_Yellow_Ardvark has some experience with blacking, a search of his posts might shed some light on how does it.

 

[Carl Wilson]

Thanks Carl. Originally I followed Paragon's advice to the letter, about making sure the ambient temperature was at least 20 degrees, plus good quality brushes etc. But after completing the spraying, I still had a few pieces left to paint, and I found that hand-brushing in a cooler temperature - say 10 degrees - worked much better. As good as the spray gun, in fact. I haven't been particularly fussy about the finish, but my first attempt was just awful.

Having (eventually) achieved a nice finish, I love the Paragon paint. It's good to use something designed for the job, and it looks fantastic. Plus Steve at Paragon has been helpful throughout so it's nice to support a British company in these troubled times.

Agree completely. The funny thing is my workshop sits at about 10 degrees all the time. I followed the Paragon instructions and they worked. I was surprised because I am normally terrible at painting.

My brother is having similar results, he is using it on his Emco V10P lathe and stand.

 

[Wallace]

A very nice rebuild. On the subject of lathes, I have my Father's Raglan Little John and another in pieces.

 

[DiyAddict]

A very nice rebuild. On the subject of lathes, I have my Father's Raglan Little John and another in pieces.

Ah, the Raglan Little John. I have such fond memories of that lathe. It would have made this job so much easier too!

 

[DiyAddict]

So, the nickel electrodes arrived - time for electro-plating. I made the electrolyte myself which was very easy. Just put both electrodes in the white vinegar with a tablespoon or so of salt, and pass a current through them for a couple of hours. Then spent a couple of hours sanding and buffing the handle. I didn't try and sand off the deeper pits, but got most of them out. After degreasing, I should have put it in some hydrochloric acid, but all I had was Hammerite rust remover, so I swabbed it neat with that for a bit, rinsed , then into the tank:

I used about 4 Volts, which passed around 0.6 amps, and left it there for a few hours to be safe.

I'm rather pleased with the result:

Ok, not perfect, but this will do me - I'm delighted! I used the same process on the table clamping handle, with even better results:

There should be two clamping handles like this - another for the missing jack. Meddings had them in stock, so I ordered one back when I ordered the jack casting. I definitely used the correct part number, but this is what came:

I'd like to say that it's going nowhere near my drill, but it will have to do until I can get access to a lathe to make one to match the good one. I think it should be reasonably hidden under the table. I had a quick look online for ball clamping levers. There are some very kinky people about!

 

[DiyAddict]

Here's the last problem I've got to solve before the whole thing can go back together (assuming my solutions to previous problems work).

Most Meddings A10 owners can boast these rather splendid clamping levers for the table arm and the articulating arm:

They're big, beefy, and undoubtedly a joy to use. Unfortunately, my A10 has only one of these levers, and this is all that's left of it :

For some reason (I think associated with the broken clamp on the table arm), a previous owner has sawn off the rest of the handle, then drilled a hole in the side for a vice-type lever. At the same time, they chucked the other perfectly good one away, according to some logic that I'm unable to fathom.

Meddings don't stock them anymore, which is probably a good thing as they wouldn't be cheap if they did, and I have to watch how much more money I sink into this project.

The thread is a 3/4" Whitworth, and I'm not even going to try obtaining a clamping lever that fits that.

Besides, it seems to me there's an easier way: buy a couple of cheap L-shaped wheel braces, and weld a 3/4" nut to a socket, so it doesn't all wobble too much.

I looked online for some one-piece braces, but the socket size would need to be 32mm. You can get those for truck wheels, but they come in two pieces that wouldn't suit the drill at all. So, as a proof of concept, I bought a couple of generic L-shaped braces with a 1/2" drive. They were less than £10 each:

So in theory, just find a socket to suit the nuts, and job done. However, I forgot about the clamp repair:

There's no room left to fit the nut in, let alone a socket on top. I'm guessing that this was the stage at which the original owner dispensed with the original handles. However, by using a smaller washer and skimming a bit off the handle, it would have fitted fine.

So here's the new plan. reduce the OD of the little stub I have left, chop an old socket so that only the half with the 1/2" drive hole remains, then weld them together:

Skimming a bit off the little stub I have left would be easy with a lathe, but I don't have one, so the bench grinder and hand file will have to do. I could do this with a nut, but the stub is original so it deserves a place in the rebuilt drill.

The stub is far from circular, so I filed away until it was - at least the part that screws into the bolt. Here it is, filed, chopped, welded, and a bit of gun blue applied to hide the bad welding. Don't judge me - this is a proof of concept, remember:

I was going to stick with the 32mm socket for the other arm, since there were no such clearance issues, but the proportions looked all wrong, so I made a potentially more elegant socket by welding a smaller one onto the face of the nut:

Well, I'm happy to report that it works! The welds are strong enough to clamp the arms so they don't move on the pillar, and even the wheel braces don't look too bad:

Of course, they're not a patch on the original levers, and I'm not sure about the black plastic handles. But I think they'll do the trick until I can find a better solution, and it's only cost me twenty quid.

I think I'm ready to re-assemble now, so we'll see what the whole thing looks like then.

 

[DiyAddict]

Well I was hoping for The Big Reveal by now, but the drill had other plans.

Early on, I posted that the Tufnol gears looked fine, and hadn't thought much about the rest of the gearbox. Well, the first problem is that the main spindle isn't straight:

It doesn't look too bad here, but the thing wobbles like a spinning top, drives the motor mount into some very uncomfortable vibrations, and gives a painful screech every revolution. I'm sure prolonged use like this cause a lot of damage to the rest of the drill, starting with the bearings. Plus, I want it to sound like 'Shhhhhhh' in operation, rather than the sort of music my stepdaughter listens to.

I resisted the urge to repair it with a hammer, and disassembled the gearbox (again). It turns out that the shaft had snapped at some time in the past, and someone had welded it on again. Apparently this is a fairly common occurrence with these drills. Unfortunately, the new shaft wasn't welded on straight:

You can see here that the shaft is welded on somewhat to the left of the spline, from this angle. Also, that part with the big spiral score? That's the bearing surface.

At this point, I realised the most probable outcome was my taking the gearbox from my good bench Meddings MB4, placing it in my A10, and being done with it. However, this sort of heart-sinking prognosis engenders a sort of freedom to experiment, on the basis that the spindle is "scrap as it is", as my dad used to say.

Actually, the offset shaft isn't that big a problem because there's enough room between the gear teeth to accommodate the extra movement. So I really only have to deal with the bend. I thought about flame straightening, but my strongest torch is a Mapp gas one I use for plumbing. It's not up to focusing the required heat into a small area. So I have to work with what I have: My Mapp torch and my clockmakers' lathe.

The general plan was to turn the shaft down so at least one part of it was straight, then build the rest up, somehow. The lathe's bed is too small to use a tailstock/centre to support the shaft while turning, but I do have a 3-point steady that could support the bearing surface. I had a couple of backup plans involving a Dremel and carbide burr in conjunction with the lathe, but they weren't necessary - my lathe could hack it!

So I'd turned the spindle such that the shaft didn't bend outwards any more, but the other side of the bent shaft then needed building up. I thought about building it up with steel weld, then turning to shape, but I think that would really be asking too much of a lathe designed for clock balance staffs in brass.

An alternative was building it up with braze, but Google told me the part was too big for my Mapp torch. However, it might be able to handle silver solder.

The problem with silver solder is that it prefers capillary action within joints. You can't just build it up per se. So here's my plan:

Slide a length of 15mm copper pipe over the shaft. It's ID is slightly larger than 1/2". Then fill the inside with silver solder, and turn the shaft true. My lathe should be able to handle the copper and silver solder, and by the time it's turned down to 1/2", there should be no copper left. Lots of 'shoulds' here.

So here's the newly turned spindle, complete with slightly tapered shaft, in my hashed-together hearth:

After tinning the shaft, I slid on the copper sleeve, lit up the Mapp torch, and started feeding in the silver solder:

I placed the spindle in the hearth with the straight part (the bit that I'd turned down) was at the top, leaving the silver solder to pool at the bottom, which is the side I wanted to build up. Then onto the lathe:

I love this photo - you can see the lathe's really going for it! I didn't have enough travel to do the whole shaft at once, so here I am with half done, and the other half about to start. This took several hours and lots of oil, but I was in the zone and the time flew by. Here's the result:

Actually, I took this photo a while later having manhandled the spindle with oily fingers, but it seems to have worked. The shaft is now very slightly under 1/2" (so you can slide the bearing on), and true. I put it back on the gearbox, back on the drill, added the pulley and what do you know - it runs lovely!

So are my gearbox problems over? Of course not.

 

[DiyAddict]

So while reassembling the gearbox for the first time, I noticed that the tufnol gears were in the wrong place. They were sitting next to each other (see page one of this thread), when they should be separated by a flange. At the time, I just put this down to the original owner not having access to an exploded gearbox diagram. However, when I added the gear lever, I realised that the lever position bore no relationship to the actual gear selected. It would just about find the edge of the high speed gear, but wouldn't stay there, and there wasn't enough adjustment in the lever housing to rectify this.

It turns out that the spline is shorter than it should be. I think this is due to the original process of welding a new shaft onto the spindle - they turned down the spline to make a new bearing surface. So if you try to select high gear, the sliding gear now hits the top bearing. I think that's why the original owner had put both the tufnol gears on one side of the flange, but that led to its own problems. So I assembled the box according to the manual and contemplated a fix.

After a lot of head scratching, the gearbox came apart for the third or fourth time. Fortunately, there's lots of wiggle room in the case castings to raise or lower the spindle, just by raising or lowering the two bearings. I had to press my gasping micro-lathe back into service to turn up a brass spacer that goes below the bottom bearing, to prevent it from dropping down during use. Then a couple of internal adjustments to the fork that raises the sliding gears - there's a grub screw for this purpose.

Sorry no pictures this time - I was too distracted - but it worked. The drill goes through the gears nicely now with a positive clunk. It's back on the drill and working well. Some time in the future, I'll find a donor gearbox or manufacture a new spindle, but this solution works fine, and there's no reason it shouldn't last me out.

By the way, some good news. I risked a 25mm oil seal in the gearbox and it seems to work fine with no noticeable leaks.

All the best

 

[DiyAddict]

Three phase and Variable Frequency Drive (VFD) - Oh yeah.

During the life of this drill, the gearbox shaft has sheared, the Tufnol gears have stripped, and the bit/chuck has spun in the Morse Taper many times. I've subsequently heard of other A10s with similar problems. I think this is because the main body of the drill is so large, users assume they can apply it to really tough jobs. That's certainly the case with my drill, which came with a load of well-used bits and reamers up to 1 1/2" in diameter. Also, it came with a 3/4hp motor, which I think is a tad too powerful for the drill head.

In fact, the Meddings blurb states clearly that the drill is designed for users who want to do relatively light work, but need a large throat clearance, to save them going to some ginormous Asquith radial drill. Despite the heft of the A10, it still uses the same drilling head as the bench version, the MB4, so it's not really capable of holes above 1" in steel without a lot of care.

My work will be relatively light - mainly wood - but I'll need it for the odd large hole in metal. For this reason, I've found a 1/2 hp three-phase motor and am intending to use it with a VFD. The variable speed will be handy, but the main aim is to use the VFD's current sensing, which will stop the drill if it draws more than a certain amperage before it strips gears, snaps shafts or spins the bit.

I've been very pleased with the Chinese one I use with my MB4. It's 1.5kW - easily enough for the motor, and it only cost £60. So I've procured an identical one for the A10:

Now, I'm happy to control the speed with the VFD's knob, but I don't want to be switching it on and off from the VFD's fiddly front panel. The Meddings Forward/Off/Reverse switch has that nice positive smooth clunk that you only seem to find in products earlier than the 1980's. That's how I want to switch my drill on.

I'm much more in my comfort zone here, having spent much of my life working as a service engineer on various electronic consumer items. The VFD is capable of remote wired control, and the Meddings switch has plenty of terminals. The only issue is that the VFD documentation is terse and ambiguous, so I thought I'd report what I did here in case it's of any use to others. There are really only three steps:

1. Connect the 240V Mains and Motor wires directly to the VFD
2. Wire up the Meddings switch to the external control terminals on the VFD
3. Tell the VFD you want to use an external control for start/stop instead of the front panel

Here's a close-up of the VFD connection block:

The large terminals at the bottom are for the high power wires: Mains in (left) and then the three phases of the Motor (right). The earth wires for the mains and the motor share the same terminal. So that's step one done.

Step 2: Above is the smaller terminal block for the 'control logic'. They are all low voltage, low current. You can use thin wire to connect to them, and you won't get an electric shock.

The terminals I'm interested in are labelled X1 to X6, and COM. You can program the each of X1 to X6 to do any function you're likely to want, for example jog forward/reverse, or emergency stop. I just need to use two of them: one for Wire Forward operation, and one for Wire Reverse Operation.

I can program whichever of X1 to X6 to do this from the front panel, but Forward and Reverse are such common operations, that two terminals are already configured to do this by default: X4 (forward) and X5 (reverse) on my VFD. Yours may be different if it's a different model, but it should come with a chart showing how each terminal is set up by default.

The COM terminal is zero voltage - it's like the negative terminal on a battery. It's also known as GND (Ground) on some models. To get the drill going forward, we just have to connect X4 to COM. To get the drill going in reverse, we connect X5 to COM. The drill will continue operating for as long as the terminal is connected to COM, and will stop gently as soon as you disconnect. So I don't have to program anything yet. I just have to run X4, X5, and COM through to the Meddings Switch. I didn't have any black multicore cable to hand, but mains cable works fine:

I drilled a new hole in the back of the motor cowl, below the motor cable, and routed the control cable through there to the switch:

Now we just have to connect the control cable to the Meddings switch. The switch contains a bewildering amount of terminals, but I just need three of them. Meddings labelled them by hand, in white. I need terminals 2, 6 and 7.

• COM to 6
• Forward (X4 on my VFD) to 2
• Reverse (X5 on my VFD) to 7

If the labels have rubbed off on your switch, as they had on mine, here's some shots of a switch with the labelling intact. One side showing terminals 1, 4 and 6:

You can see that terminal 6 should be already connected to an unmarked terminal with a black wire. If your switch doesn't have this connection, you'll need to remake it.

Here's the other side of the switch, showing terminals 2,3,5 and 7:

Here, terminal 5 should already be connected to an unmarked terminal with a black wire. It's not important for this job. The switches are identical for all Meddings M4 drill heads of this era, so you shouldn't have any trouble identifying the correct terminals.

So that's all we need to complete step 2.

If you were to switch on the drill now, nothing would happen, because the VFD is still configured to use the front panel. So Step 3: Tell it to use the external switch. VFDs have a load of parameters you can set from the front panel. Some of these are somewhat cryptically worded and have little or no explanation, especially the cheap Chinese ones. You'll need an instruction book that gives a chart of all the parameters. On mine, it's parameter P11: Start/stop control source, which can be set to 0 (Front panel), 1 (RS485 - a standard serial control port), or 2 (External Port - the small terminal block). So I just need to change it from its existing value of 0, to 2. And that's step 3 done.

This is working very well on my drill, I can set the speed on the VFD, then go to the Meddings and switch it into forward or reverse as the switch was intended. The VFD handles the soft start/stop automatically and the whole thing is a delight to use.

Incidentally, you can also configure the VFD to use an external speed control such as a potentiometer or multi-pole switch mounted on the drill head, but I'm not going to bother. I may configure it to include an emergency stop footswitch in the future though.

Apologies if this post is so long and a bit lecturey. I wanted to be as clear as possible, and I'm now going to wire my MB4 bench drill exactly the same way, so at least one person will be using these instructions .