someguynamedross.com
Various ramblings - Electronics, radio, old computers, cars & other junk...
Mini-Lathe
I'd been eyeing off mini-lathes on eBay for years, and finally caved in and picked one up in mid-late 2010.
I'm still slowly adding tools and other items to my collection such as a quick change tool post/tool holders, dial guages and various metals/plastics for turning.
It seems to be another one of those hobbies that unchecked can probably suck a worrying amount of money from your paycheque...
My lathe is a Sieg 7x14 model and it is still very much stock, so far the only changes I have made are the QCTP, and the motor controller...
Yep, not long after I got it I managed to blow up the motor controller.
I tried diagnosing and repairing the Sieg controller (went as far as replacing every active bit of silicon on the damn thing with no luck), I ended up swapping in a KB electronics KBIC motor controller module.
The new motor controller is almost identical to the original controller in performance (speed varies a little more than the original under load), and I was able to hook up a motor brake for when you hit the kill switch.
Webcam Adapter
My dad has a telescope, and he wanted to strap a webcam to the lens so that he could aim/focus without peering through a small high magnification lens and have a go at taking still images.
He asked if I could make a sleeve to attach the webcam to the telescope lens, something more stable then the blutak he did some testing with.
This little project gave me a chance to have a go at turning some Delrin stock I had picked up a few months earlier, and some more practice boring accurate holes
Very simple procedure with this one, I just needed to clean up, face and bore two different sized holes on either side of the stock.
I took my time with the boring so I didn't accidentally over-size the holes, and ended up with a well fitting sleve for the webcam and lens that is snug enough to stay put with just friction.
Delrin is strange stuff to machine, very soft which means you can take quite aggressive cuts without bogging the lathe down, and it throws some very strange "chips" depending on the sort of operation you're doing and at which speed you do them.
The only flaw with this sleeve is a slight mis-match in surface finish as I had trouble getting the chuck to hold the piece during a final pass.
Delrin is slightly greasy, and I couldn't tighten the chuck very much as it would deform the sleeve into a rounded triangular shape. Dad wasn't worried about the finish though, so I gave up trying and handed it over. One very happy customer!
Change gear cover knobs
The change-gear cover on my lathe was held on using some (very poorly made...) allen/hex style bolts.
These were a pain in the arse to remove when you wanted to change gears, but I'd seen a few websites where people had made some knurled knobs with a threaded shaft to hold the cover down instead.
Anything was better than using an allen key to remove the cover so I thought I'd have a crack at making my own.
I made thse with two parts, after being machined they were simply pressed together.
The knurled knob was made from 20mm round aluminium; cleaned up, faced, 9mm hole drilled down the middle and then knurled.
The knurling turned out very well, this was the first time I'd used the tool and I think luck played a large part in getting it right.
I made the 2 knobs from the one bit of stock, did the rough shaping and then parted them off.
This let me match the size and also get the chamfers to match as I did them at the same time without changing tools.
The shafts were made from 10mm round aluminium; cleaned up, faced, took the size of most of the shaft down to 5mm, threaded the end and then took the remainder of the shaft to a fraction over 9mm.
This let me press fit the two halves together which saved on wasted aluminium and time, much better than turning the whole thing from the one piece of 20mm aluminium!!
First Chips
While I had messed around with the lathe while setting it up and getting the hang of using it, this was my first "real" bit of turning.
I wanted a simple first project, and while I was looking around the garage for an idea I spotted an old fire extinguisher my brother found a while back.
We had planned to turn it into a portable compressed air tank, but the fitting in the top of it had too many holes in it to tap a thread for a standard air fitting.
"Perfect!" I thought, "I'll make an adapter to fit the thread on the tank, and drill a hole in the middle to tap a thread to match air compressor fittings!"
My first attempt was was done with a bit of aluminium I had been messing around with and was already a bit small.
I got a bit gung-ho while threading and it ended up undersized, it threaded OK but had too much play in the tank.
The second one is nearly perfect, I even cut a small notch in it to fit the O-ring from the original tank fitting.
If you look carefully, you can spot my dodgy setup for running the motor while I was sourcing a new power supply.
A 40v-0v-40v toroidal transformer, bridge rectifier and a filter cap running into the direction switch on the front panel.
To change speed I had to swap between taps on the toroidal transformer between series and parallel. Not the best solution, but it worked surprisingly well.
I had the ammeter hooked up to keep an eye on current to make sure I wasn't going to burn the motor out.
Mini-Lathe Bench
While waiting for the lathe to be delivered, I started looking into buying or building a bench for it to live on.
I decided to build one so I could make it to fit exactly where I planed to setup the lathe.
A quick sketch on some paper and some more time finalising the dimensions on SketchUp and I'd figured out what I needed.
I stopped in at a steel shop on the way home from work on a Friday and picked up the steel. I got them to cut it to the right lengths for me as I don't have a drop saw that can cut steel.
My only method of cutting steel is with a hacksaw, why do that when you can get it cut much more accurately with the right tools?
I welded the frame together and painted it over one weekend, and finished the tops and draws the weekend after.
Here is the finished product and a few pictures while building it.
The bench is very simple in it's construction, a steel frame made with 25mm box section for the bulk of it and some 20mm strap for bracing.
The top and draws are made from 16mm MDF, coated with some 50/50 thinned estapol to give the MDF some protection from swelling.
The frame was painted with etch primer, then some black gloss spray enamel paint.
All up the bench cost me about $150 including glue/screws and surface finishing.
The draw handles and a few other things I had kicking around the garage but they wouldn't add a great deal to the total cost.
