Unimat 3 Lathe - Dremel Milling Attachment
Updated 21 June 2022
Emco Unimat 3 Lathe With Digital Readouts
I purchased an Emco Unimat 3 lathe in 1979 at the World Trade Fair in Wellington, New Zealand. The exhibitor was Grossmans General Engineering Suppliers. This particular lathe had some slight cosmetic damage owing to a light contact of the chuck with the edge of the cross-slide during a demonstration. I was able to get this lathe, plus accessories, at a substantially reduced price. The Emco Unimat 3 is a complete small lathe.
Over the 43 years I have had this lathe I made good use of it, making small parts for electron microscopes, optical microscopes, mass spectrometers, rain gauges, bikes, weaving looms and a collection of small tools for the workshop.
Emco Unimat 3 Lathe
I made a little gauge which allows the cutting tool height to be set at 23 mm above the cross-slide. This gauge is shown at right. Shims could be stuck to the base of each cutting tool so the cutting height was the same for all tools. This would be almost as convenient as a quick-change tool-post
I added a low cost Mechpro Blue Digital Tread Depth Gauge from Repco to monitor the cross-slide. Similar gauges are available online at low prices. These gauges have the same resolution but slightly less reading stability. The error in 11 readings, at 1 mm intervals, is 3 times greater than with the Mechpro gauge. The Mechpro readings are reliable to within about +/- 0.015 mm.
The gauge was mounted to the right-hand side of the cross-slide. A small magnet was glued onto a rigid triangular tab, made from a paper clip. It attracted a ball-bearing, drilled and mounted, on the gauge probe tip. It takes much more force than the gauge applies to move the magnet more than 0.01 mm. I get a working range of about 28 mm with a resolution of 0.01 mm.
I originally used a dial-gauge to monitor the cross-slide but it did not fit well with a small lathe. I used it to monitor the diameter and centering of work mounted in the chuck. For centering with the four-jaw chuck a dial-test indicator is the more appropriate tool, shown at right.
I added a second digital tyre gauge which gave me a 27 mm working range for the carriage movement. The gauge attaches magnetically to the front V-guideway of the lathe bed and can be slid along to suit. A magnet glued to the saddle attracts a ball-bearing tip attached to the probe of the gauge.
The gauges are secured, with two magnets, to either the bed front V-way or to the right-hand side of the cross-slide. In both cases the magnets are mounted on a custom steel plate attached to the back of the gauge. For the strongest attraction one magnet has the North attracting pole facing out while the other magnet has the South attracting pole facing out. This creates a single flat, but very strong, magnet.
The digital gauges will sleep after an imprecise 6 minutes, if undisturbed, and they wake up when there is any probe movement. The previous reading is remembered and the new movement is added to the display. This mode of operation is unusual and very convenient.
The gauges can be easily lifted off if they get in the way. The gauge mounting positions are well away from most cutting debris. I spent about $30 on the digital readouts, including the magnets. The gauges are shown above and at right.
The Mechpro gauge now has two sets of magnets shown at right, A single gauge can occupy either the cross slide position or the lathe bed position. This reduces clutter. If I require both measurements I can borrow the digital gauge from my South Bend lathe, as shown above.
Some of my lathe projects are shown at right.
Mostly I use the three-jaw chuck, taking care that the mounted work is nearly true before doing any cutting. The small soft-face hammer shown at right can assist with any final adjustments, with the aid of a dial-test indicator.
I glued some magnets at the end of the lathe bed to hold some tool bits, a centre-drill and a few lathe tools shown at right.
The photo below shows, from top left, a range of accessories including a depth gauge, a scriber made on the lathe, a lathe-dog, a range of cutting tools, two dead-centres, a machine-vice, a milling table with a work clamp made with the Dremel milling attachment, a four-jaw chuck, a face-plate, a centre-drill, and a steady-rest in the middle.
Lathe and Milling Accessories
For me, the basic lathe is sufficient for most needs. The top-slide, for taper turning, looks a bit light-weight to me, so I don't have one. For decorative tapers I can always follow a paper template. In this case the power-feed gear is helpful.
I have a four-jaw chuck for accurate work The three-jaw Jacobs style drill chuck is also accurate and it easily mounts onto the head-stock. This is also a good substute for an expensive collet set. For holding threaded parts the collet set is better.
I don't have any threading attachments as a good tap and die set is sufficient for my needs. I use the lathe tail-stock as a support for accurate threading. In many cases already cut threads on nuts and bolts can be added with some accurate press fitting.
Dremel Milling Attachment
For milling I have a Dremel 3001 Rotary Power Tool mounted on a Dremel Rotary Tool Workstation. The workstation is essentially an adjustable drill press and a stable support for the Dremel Rotary Power Tool. The base was removed and the remainder mounted rigidly onto the lathe base, using a mounting collar made on the lathe. It uses a micrometer barrel to hold the cutting depth precisely. The micrometer bears onto an embedded ball bearing at the top of the drill press quill.
I made the mount for the micrometer with the Unimat 3 lathe and the Dremel mill. The micrometer can also be mounted below the Dremel to act as adjustable drilling stop, although there is a good one built into the Dremel Workstation.
There are two small locking screws near each end of the Dremel Workstation quill, on the left. Doing these up, after the cutting depth is set, makes the Dremel much more rigid. The normal setting has the screws backed off slightly. There are two more screws, supporting the depth stop rod, which can be adjusted in the same way.
Unimat 3 Lathe with the Dremel Milling Attachment
There is a machine-vice which attaches to the cross-slide of the lathe. The cast iron jaws of the machine-vice were levelled by milling a shallow cut across the top. The flat milling table, shown above, was made with the milling attachment. The table was clamped in the levelled machine-vice for milling.
I also milled a range of work clamps for the milling table. There are a number of tapped holes in the table to allow the use of several clamps at the same time. The photo below shows a range of Dremel tool bits at left. In the middle are some clamps for holding work on the milling table. At top right there are six collets and two collet-chucks.
The Dremel milling attachment is intended for work with materials like polycarbonate, Acetal, Nylon, Teflon, machinable wax, wood, and aluminium. Light cuts are required as the Dremel is not as rigid as a normal milling tool and there is limited torque available. The rotation direction of the tool bit at the work surface and the advancement direction of the work should be opposite to prevent the tool bit grabbing the work piece.
The Dremel 3001 has an unloaded slow speed of about 5000 rpm. The maximum speed is about 35000 rpm. The torque is much lower than with a normal milling setup, so light cuts are needed, perhaps at a higher speed than usual.
The Dremel can keep tools sharp, with a light touch from an abrasive stone or a diamond tool. The Dremel is moved on the supporting pillar so it can be inserted into a paper cup behind the tail-stock. The cup shields the lathe from any abrasive particles. An aperture in the side of the cup allows a tool to be inserted for re-sharpening. The Dremel is also used for finishing work. The setup is shown at right.
Low Cost Lathes
In 2022 there are different choices of mini-lathes which are good value. Metric or non metric versions are available. Sherline lathes are popular. There is a wide range of mini-lathes from various brands with similar specifications. A Toolshed Mini Engineers Lathe is one metric rebranded lathe available in New Zealand. Another lathe available in New Zealand is the TU-1503V Opti-Turn Bench Lathe from Machinery House. The links at right will help to find other brands.
Another option is to recycle and update an old lathe. I have an old 9 inch model C, South Bend lathe, which is perfect for larger work. It has standard change gears, a screw feed, a taper attachment and a spindle hole 3/4 inches in diameter. It does not matter too much to me that the lathe is calibrated in inches. A metric digital tyre gauge is used to monitor the cross feed. A modified plastic 150 mm digital calliper does the same for the carriage movement. Alternatively the work can be fully marked out before machining. Marking blue or a marker pen can be used as a strong background colour before scribing the reference lines.
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