5 February 2015
Much as I love my little MD65 lathe and the BFE65 mill attachment, the D-shaped lathe bed is simply not substantial enough for milling. Fortunately my mill came with the standard KT200 milling table (rebuild log is here), so I welded up a table to mount the mill and also a Fobco Star drill press.
Materials, design & construction
I welded up the workbench using my Butters AutoWeld 140 gas MIG. If you are thinking of buying a welder for general work (steel & stainless), get a gas MIG – these are by far the easiest and fastest machines to use.
The majority of the structure is made of 3mm thick, 75x40mm box section steel. I got this as ‘offcuts’ from a local welding fabrication workshop. It was out the back of the workshop and covered in rust. I negotiated what I think is a very good price of £50 for the lot (enough for the bench and more besides).
The mill table itself is mounted on steel cross-members welded to the top of the workbench frame. I did it like to this for maximum rigidity, so that I could bolt the mill direct to the structure of the table, with metal to metal contact. I drilled four sets of mounting holes at 50mm spacing, to allow the mill to be moved forward and backwards on the worktop. This is to allow space for stepper motors to be added later…
Mounting holes for the mill. The steel frame of the workbench is finished with two coats of satin finish black Hammerite, applied with a small foam roller.
The worktop is just a cheap and cheerful 28mm kitchen worktop. These worktops are not particularly strong, straight or impact-resistant, but they are cheap and the surface is very easy to clean up. I went for the kitchen worktop after the plain ply worktop on my lathe workbench became so stained and embedded with swarf that I could no longer clean it.
I made some adjustable feet out of M20 threaded rod, some M20 nuts and some 5mm plate. The ‘feet’ are drilled with 10mm holes to allow the workbench to be bolted to the floor. As the nuts were zinc-coated, I ground off the zinc with a flap disc on an angle grinder – inhaling the fumes from molten zinc during welding is to be avoided… I cut a section out of each leg to allow the locknut to be tightened.
I welded a nut to the foot plate, then screwed in the threaded rod and welded this to the nut. This assembly is inserted into a 20mm hole drilled in the plate welded to the bottom of the table leg. This design worked OK, but I found it difficult to tighten the lock nut (visible inside the table leg) for the legs next to the wall, as there is no space to swing a spanner.
Like most hobbyists, my workshop is a multi-purpose space, that I (grudgingly) share with others in my household. In order to protect the mill and tooling from myself (grinding dust & sawdust) and Mrs Naut (concrete dust & dirt from the garden), I needed to be able to enclose the worktop. So I built a cowl/cover out of 12mm shuttering ply, screwed and glued to some 20x40mm battens, and the whole lot painted with oil-based exterior paint. In the photos I have not added any shelving or storage as yet, mostly because I don’t know exactly what I need.
On the electrical side, behind each of the machines is a double power socket enclosed in a waterproof box. These sockets are connected to a length of 2.5mm flex cable (rated at ~20A at 230V), which has a 16A plug on the end. This plugs into a 16A socket running direct to the fuse box for my garage. The machines don’t draw anything like this kind of current, but I hope to add CNC to the mill in the future which may strain a standard 13A plug.
The cowl includes a most excellent 4ft LED tube light, with a switch in the cowl itself. I recently converted some of the fluorescent tube batten fittings in my garage to daylight temperature LED tubes – the difference is amazing. LEDs make old-fashioned fluorescent tubes look dirty and dull. I like them so much I got another 4ft batten fitting and LED tube for the lathe.
Milling on the MD65 lathe bed
I struggled on for a year with the mill head attached to the lathe via the ‘foot’ that bolts on to the side of the lathe bed, however I could only ever manage side-milling, because if the work was not flat on the t-slot table then the chatter and vibration would cause all my tools to fall off the shelves! There is a review of the MD65/BFE65 in the February 2015 (issue 225) edition of Model Engineers’ Workshop, the author came to the same conclusion.
This problem came to a head for me when I attempted to use a new milling vice: I simply couldn’t use the vice as it lifted the work about an inch off the t-slot table, which was enough to make the t-slot table visibly judder. Also, there just isn’t enough space on the cross-slide mounted t-slot table.
After removing the mill head from the lathe, I also found it much easier to see what was going on when turning, as I didn’t have to keep ducking my head around the mill.