The tailstock DRO is now completed. The last element was a block to bolt to the existing end clamp, to hold another rare-earth 12mm magnet which keeps the end of the scale firmly attached to the tab on the quill. See part 1 and part 2 for details
Having made the clamp collar and bracket to fit the quill (see part one), next step was to make the magnetic wedge to fit on the angled side of the tailstock on the Colchester 1800. It is inclined at 6.6 degrees. I wanted the digital display to be at 45 degrees to avoid glare and keep the LCD reading angle good for best contrast.
I needed a DRO (digital read-out) on the tailstock quill of my Colchester 1800 lathe. OK, the quill has an engraved mm scale and the wheel on the leadscrew is calibrated in mm, with 2.5mm per turn in multiples of 100 micrometres. Still a pain when you need to drill a hole 52.95mm deep. After watching a couple of Youtube vids, I saw a neat solution by ChrisB257. Make a collar to be a very close fit to the end of the quill, split it and put in some clamp screws, then fix a right-angled tab which can be used to attach the magnet on the end of a sliding electronic digital scale.
So, part 1 is just the quill clamp collar and magnetic tab. Collar is turned from 70mm EN3 steel round bar. Tab is from an offcut of EN8 I found in the scrap bin.
A SCAM12 weights something over 90kg, and with a rotator and antenna system, it it rather too heavy to lift from horizontal. However, putting it to vertical then trying to lift the antenna up high enough to drop it into the socket on top is just too dangerous. Solution is a winch from the local agricultural merchant.
Nice simple job, making up another rotator mounting plate with a 40mm spigot to fit a SCAM12 socket.
I found a nice old HP3400A True RMS thermal millivoltmeter on ebay. Very useful for sun noise measurements. Unashamedly analogue.
Nothing to do with Radio. Caroline asked me to make a meat-tenderiser. Aluminium and stainless steel.
A friend asked me to make a heatspreader for the 23cm amplifier board from VE1ALQ (SK)
Rather than mess about with a sectional spreader, we decided to do a large single block of copper to maximise RF performance.
Part of the design decision for the spreaders I made for the VHF PAs was to use pockets machined in the copper surface of the spreader to carry the MRF151 transistors, which protrude 2mm below the PCB. As I don’t have a CNC mill, I had to make a fixture to hold the spreader accurately in place while I machines the pockets on my Bridgeport.
These surplus high power PAs using 4 x MRF151 were originally used in watercooled industrial VHF drivers. The devices and some of the other components protrude about 2mm below the PCB lower surface.
To minimise the amount of copper required, I decided to make a heatspreader to go under the devices and make aluminium spacers for the rest. I also decided to make a fixture to hold the spreaders so I could cut neat pockets for the devices. Not sure that was a sensible approach. It certainly meant I had to do some tricky machining.
I have some more to make, I won’t be doing the fancy pockets this time, just transverse slots.