Milling/ drilling machines (Updated 130922)
Bridgeport 1ES Horizontal Milling Machine
One of the first things I bought via Ebay, and formerly in a Yorkshire college, this 1ES was built in Leicester in 1980. It was originally produced by Adcock & Shipley, who ended up as part of the Textron group which included Bridgeport, hence the badging. It's a horizontal mill with power traverse on the x-axis. The machine weighs in at 1600 lbs and had to be delivered to my workplace and stripped down for removal to the house. I converted it from 3-phase to single-phase electrics with a 3hp motor and new coolant pump. Also via Ebay came the dividing head and 2-axis work vice. Cleaned up and painted a similar shade of grey to the mill, they almost look to be original equipment! I acquired an ER32 collet chuck which is a bit tricky to use on a horizontal mill, you have to think in a parallel universe to work out where the cutter's going. UPDATE Aug 14: After owning the 1ES for about ten years I finally managed to land a vertical head for it! I was just logging-on to Ebay when I spotted it amongst the pictures of items recently listed. I paid more for the vertical head than I did for the mill itself, but that's the way of things. Anyway, some pictures...
1ES complete with tilt & swivel vice, dividing head, Lotus brake caliper, Nokia mobile (2002 vintage) and coffee mug...
Vertical milling head (in Adcock and Shipley's earlier colour)...
Top view showing tilt scale, lifting eye and drawbar bore...
...and looking from underneath at the business end (DTI mounting bar at top centre):
It looks a bit scruffy; this is largely due to machinery makers using large quantities of filler to create smooth surfaces on their castings; unfortunately it's not possible to move 43Kg of cast iron around without incurring some damage to the paintwork! The important parts are in perfect order and it runs smoothly and accurately.
More info on the 1ES can be found here.
This machine is a bit of a puzzler. I acquired it through my company when we bought out one of our competitors but have been able to discover very little about it or its makers, other than that Perrin are (or were) a respected Swiss company who have produced some very expensive milling machines!
I think it's fundamentally a pillar drill (possibly a 'co-ordinate drilling machine') though with care and light cuts is it capable of being used as a vertical milling machine. I've never seen a pillar drill with a column anything like the size of the one this has (90mm diameter)! The 'head' moves up and down on a rack and pinion and can be swung around the column (but is only locked by friction hence the necessity for light cuts when milling). The x-y table has about 7" of travel in each axis (but no power feeds as on a 'true' mill). A two-stage, 5-step pulley drive is fitted that gives an impressive range of speeds (about 60-10,000 rpm!), and the spindle can be interchanged to give either a threaded nose to which chucks can be attached, or a Morse tapered socket for suitable tooling. A selection of tooling came with it: flycutter, Jacobs chuck, ER25 collet chuck, &Y axes use Imperial leadscrews and are calibrated in thousandths of an inch, the z (quill) axis is Metric! Confused? you will be... and to make matters worse for a modern operator the leadscrews have right-hand threads, which means that when you expect the table to move away from you, it comes towards you...!
From the few pictures I've been able to find, it appears the Perrin originally ran with its belt drive mostly exposed, with just a cast dome at the front to keep the operator's hair out of the belt, as seen in this picture of a fairly tidy example I found on the 'net:
Mine has had a home-made cover of plywood and sheet alloy added to improve safety, if not visual nicety:
Some of the tooling (Jacobs chuck, ER25 collet chuck, boring head and 2MT spindle):
The tooling is stored in the base, on a wooden panel fixed to the inside of the door:
One thing that had perturbed me since I got the Perrin was that the 'universal' spindle (the one with the threaded end to fit the various chucks etc.) appeared to be bent, but I'd never managed to get the locking rings undone to pull it out:
I made some 'C' spanners from 5mm steel plate with sawn-off bolts welded on as pegs and had the spindle out in moments. I put it on Vee blocks and rotated it and sure enough it's bent. Not much, but enough to make it pretty inaccurate! I fitted the 2MT spindle and that runs spot-on. My lathe has a 2MT-fitting Jacobs drill chuck for the tailstock so I plugged that into the Perrin and straight off it drilled better holes! Closer inspection of the 'universal' spindle reveals a selection of marks that imply to me that someone has previously tried to straighten it in a press or similar. As luck would have it, we had a job at work that required the manufacture of several precision parts. I was able to slip the bent spindle in to the machine shop and they produced a new one. I was finally able to mill things with a reasonable degree of accuracy!
DIGITAL READOUTS
The Perrin has been well and truly hauled into the 21st... well OK, the late 20th... century, with the addition of digital readouts! I don't even remember how I came across it, but some guy's website had brief details of how he'd fitted a DRO system to an old mill. Some time was spent surfing the 'net and I ended up buying a system from these people. Three digital scales (like digital calipers) are installed to each axis of the machine and a cable from each feeds the DRO itself. It took some work to get the X and Y axis scales installed; I haven't done the Z (quill) yet as there's so much going on at the front of the Perrin's head that I can't yet see how to mount the scale. I used the machine to make some reference blocks used in the calibration of ultrasonic test equipment and the setup time was vastly reduced compared to the previous blocks I'd made. In the process of installing the slides I found some play in the table gibs that was probably largely responsible for some inaccuracies I've noticed in the past (talking ten-thousandths of an inch here!) and having adjusted the gibs I'm pleased to see an improvement in the finish quality of some slots I milled. With the DRO system in Imperial mode I can easily work to the maximum resolution of the scales (5 ten-thousands of an inch). The DRO unit is a 3-axis one (that no longer seems to be available) and the scales are 150mm and 200mm versions of the vertical types here. The supplier also offers horizontal scales but the ones initially supplied would not work with the DRO so they swapped them for me, once I pointed out that they were 'positive earth' and the DRO needs 'negative earth' signals in order to function correctly. As the scales are mounted underneath the X-Y table of the mill they are inaccessible anyway so it doesn't matter that they are the 'wrong' type. The main drawback of these Chinese-made scales (including most digital calipers) is that they are affected by water; I don't have flood coolant on the Perrin so as long as I'm careful with my squirty bottle of soluble oil I should be OK! I plan to modify the system so that the scales are supplied with DC from the DRO unit, rather than running them on batteries, as they're a bit difficult to get at for battery changes. And besides, I'm a skinflint ;o)
UPDATE 100511
I sourced a 1.5v regulator to power the linear scales, lashed-up a small circuit board and fitted it into the DRO unit. Conveniently, the sockets for each scale input had uncommitted tracks for what I took to be the + feed so it was a quick install. Shame it didn't work :( It transpires that the linear scales are positive-earth, but the DRO is negative earth. So the scale chassis' are connected to the DRO ground. Consequently the scales did nothing. No problem, thought I, simply reverse the polarity of two wires in the connection cable. This time the scales powered-up but the DRO didn't respond. Er....?! I had a bit of a think. The solution seemed to be to have the new 1.5v supply reversed relative to the DRO ground, but obviously that wouldn't work as the 1.5v regulator used the same ground. What was needed was another power supply! I rummaged in the loft and found an old Nokia phone charger with nominal 5.7v output. I wired it to the 1.5v board, reversed the connections from there to the DRO and hey presto, everything works.. however the display tends to be unstable - which I think was noted by another website author when he tried externally supplying the scales. I found that some suitable suppression components soldered across the edge connector of the scale's PCB cures it. I had a suspicion that the DRO wouldn't like the various electromagnet fields created by the 3-phase inverter and sure enough, when I switched on the mill the displays went haywire. They were perfectly stable when the scales had batteries in them though, so it's 'just' a matter of suppressing the electrical noise now...
UPDATE 291112
Time passed, as it does, so it was only this week that I determined to resolve the issues with the DRO installation. A couple of other websites outlined a technique for modifying the scale units to be negative, rather than positive earth, as a means to help the interference suppression. I dismantled the units, which involved drilling out some brass rivets, made the required changes and reassembled. Testing showed that the original problem remained :(
As a last-ditch attempt, I stripped the scales down again and soldered in some extra capacitors... and, finally, it works! I ran the table from end to end of both axes to determine the maximum travel, then set the table dead-centre and went for a takeaway, leaving the motor running. Three hours later (I eat slowly, OK?!) the DROs were still showing the table dead-centre, with not a flicker on either axis. I can attain 190 mm of travel on the X-axis and 164mm on the Y, restricted by the table hitting the column! I've tried wiggling cables, dropping the mill head to be closer to the table etc., and it's rock-solid. About bloody time :O) Rather than sully this page with pictures of circuit board carnage, I've put together a separate page to illustrate what's involved.
Incidentally, if you happen to look up Perrin on the 'lathes.co.uk' website, there's now mention of this 'co-ordinate drilling machine'... and the two pictures shown on there were shamelessly stolen from this site with the backgrounds edited out (OK, yes I know, I got one of them from elsewhere myself... :D)
UPDATE 130922
As time went by (all ten years of it!) I noticed that the DRO would frequently start displaying random gibberish, losing the all-important numbers to tell you where you'd got to with the cut :( It would happen even if I was cutting dry so I knew it wasn't coolant getting into the works. Eventually I realised that the connectors on the end of the cables to the scales were responsible, so I've finally got around to chopping the plugs off and hard-wiring the cables, which for the moment at least has restored stable readings.
The odd angle is to reduce the amount of light that was being reflected from the display. GL-08 is an error code which the DRO unit shows if there's no digital scale connected; in this case the Z-axis as I still haven't worked out how to mount the scale for it on the front of the Perrin's head! A quick look around the internet shows the 3-axis display is probably no longer available, or at any rate as rare as hens' teeth. Amadeal haven't stocked it for some years and I can only find a couple of companies in the USA who still list it on their websites.
One day, I was browsing on Ebay (as you do ;-) when I happened upon a Rotary Table. For the uninitiated, that's a cast-iron circular table used to accurately position parts on a mill for drilling etc... and it rotates. So if for example you wanted to cross-drill some brake discs every 'x' degrees, a rotary table will allow you to turn the disc exactly the right amount to line up for the next hole. It's 12" in diameter and badged by Jones & Shipman:-
As you can see it's a shade too big for the Perrin, though it's just possible to position it so that the centre of the table is central to the quill, and a large pair of G-clamps seems to keep it in place well enough. The table weighs over 50Kg as it's basically a cast-iron T-slotted platter on a cast-iron base with a reduction gear and a brake.. probably made from cast iron. The table is graduated in degrees and the vernier in minutes of rotation; there's about 4 minutes of lash in the reduction drive which I reckon is acceptable given the jobs I'm likely to have for it. I stripped the table down and cleaned the gunk out: with a liberal squirt of oil it now rotates smoothly with little effort. The price was right too: the seller was out in the sticks about 30 miles from Aberdeen and the table was 'collection only' so I guess it limited his market somewhat. I happened to be in the north of Scotland on business and was able to detour to collect it! The pin you can see in the middle is attached to a plunger that can be used to clear swarf out from the centre hole; in a flash of genius I turned it to a tapered point and with a threaded centre fitted to the end of the spindle it becomes the work of seconds to set or reset the table dead-centre under the quill (though the Perrin's new DRO system now takes care of that anyway!).