The L word and the M word
As I sit and type this I now own a Lathe and a Milling Machine. This is something that -to be quite honest I never thought that I would need, and it is only now after nearly 7 years of building locomotives that I find that I have finally hit the wall...
It began when I started looking at the EE-1.
The wheels for this are quite simply unique. No Model Engineering firm that I contacted would even contemplate machining them for me. This meant that if I was ever going to have the wheels to build this model, then the only person with the money and time to do it -would be me. I had researched the problem of buying a lathe for wheel making in late 2007 and by the New Year I had decided that there was no lathe suitable. Then I saw a picture of the wheel making machine originally used by the Great Western to produce their titanic drivers for the Broad Gauge locomotives. Technically it is a form of capstan lathe -but it had a rotary cutter. I got the thought that I could duplicate this in a "domestic" environment using a cheap milling machine and a rotary table and I went forward with this idea.
Then I got lucky(!)
Several UK machine manufacturers use common castings from Chinese sources -this produces a sort of "clone" market for various machines with a few pounds difference here and there. I bought my "clones" from Chester Tools over the web and they delivered them the following Friday. I do not know if these are New Old Stock -or last years paint colour - but I got them at a good price and saved myself a total of £219 on the total cost of the two. I also got free set up and delivery!!!
The machines had to be "light", (yes I know 25Kg is not "light" -but I can lift it on and off the trolley). They had to be single phase AC and run off the domestic 13A mains. They do an option of a Three-in-One (mill drill and lathe) but I have never really fancied multi-functionality in my tools and I prefer my single lathe, drill, and mill in a row on the side.
This is the Lathe -it is a COBRA
This is the Mill -it is also a COBRA(!) The 100mm rotary table is on the top of the compound table.
According to several reference books that I have, the lathe that I have bought, (2 1/4 inch), is too small for 16mm and Gauge 3 work -but since the main drivers will be cut on the mill the smaller wheels can be quite easily turned on the little lathe. I don't think I need anything as large as a Myford 7 -when most of my wheels are going to be less than 60mm diameter(?)
I have opted to go for a set of 5 replaceable indexed cutters for my Lathe Tools. I will never have to sharpen them and being Tungsten Carbide they will cut through "gritty" cast iron as well as steel. The "Rating" is called C6. This is very useful when cutting wheels from commercial castings. The same goes for my Milling Cutters, the formulae that work out how fast a cutter can turn when milling steel, shows that I can never over speed the cutter if they are Tungsten Carbide -my motor cannot turn them fast enough to get into the danger zone.
I have decided to go for only 3mm, 4mm, 5mm, 6mm and 10mm cutters for my milling machine. These are the common sizes of bolts and shafts for my models. The 10mm cutter will be used for milling the flanges of the wheels as this "should" give a more even cut.
A few months have passed and I am (I think) starting to find my way around my lathe. My first purchase for it has been a bigger chuck -it is 100mm 4 jaw. When I first ordered it I looked at my 80mm 3 jaw and thought -OK it will only be 20mm wider than that -no problem... However when it was delivered with the adaptor plate there was an; "Oh My GOD (What Have I Done)???" moment -it was HUGE. It weighs in at 2.3Kg and is somewhat unwieldy. The instructions for the adaptor plate are very simple and I followed them with some trepidation. The idea is that the spigot end for the chuck is slightly oversize and then you turn it down to fit the insertion lip on the new chuck and this is automatically centred for your lathe -because it has been turned on your lathe. Then you mark the back of the adaptor plate and then a matching notch is cut on the drive spigot and everything is "true" to itself. All that remains is to bolt the allen screws through the adaptor plate and then nut the chuck up!!!
Famous Last Words...
I didn't have enough fiddle space for my huge hands to nut up the adaptor plate... So I had to take it off. Then I found that the supplied allen bolts (which fit the M8 threaded holes in the 4 jaw chuck perfectly) were slightly too big to fit into the sunk holes in the adaptor plate -because they had knurlings on them. So, I had to re-install my 3 jaw -take a few millos off the allen bolt, (to strip off the nice knurling), and then bolt the adaptor plate to the chuck. Success!!! The only problem now was how to hold a freezing 2.3Kg chuck plus adaptor plate while trying to nut up the adaptor plate to the drive spigot, in the November icy cold. After several dictionaries of "words" they all sat square and tight. I delicately spun it up to speed and there was no visible run out or vibration. I think the install can be classed as a success.
My next purchase will probably be a "compound slide" that will help me cut tapers and flanges.
No -It Wasn't!!!
As I have written elsewhere -beware of technology.... I have been unable to use my lathe for several days due to a one very simple thing the fuse holder. The lathe developed the odd habit of not wanting to start -or of stopping dead when it vibrated a lot due to my, (admittedly), very poor knowledge of how to use of it. I had started to put this down to the electronic circuit board cum speed controller on the lathe -but there was BANG and the fuse holder blew. The fuse blew with such force that it shattered the glass capsule, thus rendering the twist and unlock function of the fuse holder -impossible. By dint of main force I got the top off the fuse holder and inside -well it was not very pretty. I blew out the glass shards with a length of poly pipe and tried a new fuse -now the fuse holder top would not stay in. A quick telephone call with Chester confirmed that I would have to fit a complete new fuse holder and a trip to Maplins acquired me TWO new ones and a box of ten 1 Ampere 240V fuses. Tomorrow is Saturday and I can have a nice time spending all day rewiring my lathe...
It is now Saturday Lunchtime and I am very pleased to say that I have replaced the fuse holder. This was possibly one of the most AWFUL jobs that I have ever had to do. I come from a computer industry back ground and, (in the early days), it was not uncommon to have to rip off the panels and replace the boards with new ones. It became a guide that the reliability of any computer system was evident from the number of original screws missing from the service panels... After this mornings work in a sub zero shed with a set of screw drivers, allen keys, et al, (and this was BEFORE I could get hold of the control panel), I have decided that when warmer weather comes -I will build an external control box!!! The electronics are buried deep within layers of layers, and it took the best part of half an hour to unearth the back of the panel. The next problem was to get the soldering iron into position but I have a nice collection of home made "custom tips" -including one that is U shaped -which I had to use. Having freed the connections I then had to unscrew the back and then replace it with the new one. Which of course did not fit. A quick check with the calipers showed that it was 12.7mm dia with the original hole being 12mm dia. I wrapped a rag around a twist bit and wound the hole out to size. Normally I would have used a broach -but I don't have one that is short enough...
The lathe now goes round (and backwards) when required. I must re-itterate that I love this lathe. With a little work it could be made to be a fantastic tool. I now see what they say when you buy a Chinese lathe you MUST consider it to be; "A kit of parts".
The New Year has arrived and I found that my Mill lacked torque -in short it simply stalled when cutting. I phoned Chester who suggested that it might be the settings on the servo control and it was delicately twisted 5 degrees clockwise. Still nothing. I noticed that the Mill was vibrating when it stalled and I asked my small son to tell me if the motor was still running. "Yes Daddy -it is going round like the clappers!!!" he signed. Hmm??? I undid the motor from the top and unlimbered the motor, one feel of the plastic gear wheel told me everything about its condition... The gear is held in place by a metal wedge and the gear held onto the shaft by a circlip. The metal wedge had carved its own groove around the gear -in short there was no connection between the gear and the shaft!!! A short space of time supplied the required TWO spare gears. (I have gone through one gear in three wheels I have 11 more to do). A gear puller still marked "Property of Rhodesia Rail" whipped the gear out and its matching gear crowner tool marked "Property of British Rail" pushed its replacement back onto its shaft. Time to get it back into operation. One of the problems I have been having is sourcing inserts for my cutting tools. I have wasted one month waiting for a supplier to get them to me only to find them on eBay. I PayPal'ed the money at 8am and the parts were with me 11am the next day. It seems that the next set of lathe tools that I buy will have to be made by GLANZ as everybody seems to stock their inserts!!!
The next purchase on the list for my lathe is a "face plate". I now have all six driving wheels for my loco and I am just starting to produce the eight bogie wheels for it. The face plate is one of those things that I should have invested in as one of my first purchases, (although I knew I would need it I thought I could get away with waiting until I really needed it). Similarly the Compound Slide(!) these have turned out to be very rare items indeed for my lathe. It is one of those items that are always listed by the suppliers -and always out of stock.
Well I got the face plate and new set of Glanz lathe tools just after 8am on the Saturday morning -less than 48 hours after going "click" on the check out icon. I unpacked the face plate and scraped the (ugh!!!) red packing grease into the bin and then dangled it of a hook outside and sprayed and brushed at it until it came clean. The plate fitted too perfectly to the stub on the lathe -four attempts with rags to get any grit out of the recess and it fitted! A delicate kiss with the rubber hammer and it clunked home...
Then disaster struck!!!
I refitted the 3 jaw chuck cut the 5th wheel and went to have lunch. I came out from my Cheese&Onion Doorstep and mug of tea and flipped the toggle to forwards -nothing happened. I nudged the stop switch and tried again. This time the the lathe spun up the full revs and I hit the off switch. I assumed at this time that the knob that held the potentiometer behind it had become dislodged and the position of the pointer was a false one. I turned the knob down and it sat at the 100 revs position as it should do. Flip the toggle to forwards and yet again it went to full revs. I switched it off supped some more tea and tried again -NOTHING. Since that afternoon the lathe has ignored all the controls.
I posted a query on a C1 forum asking for advice and got a post commiserating with me... I rang Chester Tools on the Monday morning. They advised me to un ship the board and post it to them. The problem with doing that was that the PCB drawing in the book bore no resemblance to the PCB that I was looking at. I went into town bought a load of cable tags and "ringed" as many of the cables as I could. I did later find that most of the cables had been ringed originally -but they had all slipped down the cables and disappeared into the darkness!!!
Here is the PCB that the lathe is fitted with:
I think that the Chinese must use very different colour codes to what I am used to -as all the main cables are either BLUE or BLACK. At the bottom of the picture you see the, (EU), std colour coded cable Blue, Brown and Green/Yellow -which is the 13A 230V 50Hz feed from the "mains". The two blue cables on the bottom left hand side marked X3 and X4 are, (I think!), the feeds to the DC motor, the relay for switching can be seen, (just below and to the right), of them. Right at the top is the 3 pin plug for the potentiometer (Black,Yellow, Red). The bank of screw connectors at the top are somewhat mysterious!!! The white "brick" with the Black cables going into and out of it I assume to be some form of inline supressor, as it supplies AC flux to the board via the screw points marked L1 and L2, (both with Black cables). The first screw connection is a puzzle it is marked GNA (?) I assume this to be an Earth connection as there was an unconnected Earth cable on my lathe and the GNA screw connection was empty... The next two connections are marked K1 and K2 and are Blue, these seem to be straight DC -is this the field windings supply for the motor(?) What the central Red and Black plug socket seems to connect with -I have no idea!!!
Well I gave up and had the whole thing shipped back to Chester tools -free of charge! Since its return it has performed faultlessly. I have had chance to sit down and do some "dissection" of the maze of cables that are hidden within. Below is the plan of the Circuit board.
WARNING!
Keep your fingers well clear of X3 and X4 as they are ALWAYS LIVE.
The next two links are PDFs for guidance about what is available for the type of Lathe and Mill that I use: