Tuesday, 29 July 2014

Shortening the screws

So that the Topsy Turvy Clock has a good finish I decided to trim some of the brass screws so that they would be flush with the plates rather than sticking up proud. To facilitate this process I made a simple filing plate.

This is an old scrap of steel in which I've drilled and tapped a 3mm hole.



I did try to harden this but I think I did not get it hot enough as the file still cuts into it. However because the brass is softer than the steel it's not really an issue and the plate does it job.

To use the plate you basically screw the screw through the hole and then saw to length, the ragged end is then filed. When the screw is removed from the plate it ensures that the thread is not damaged. I've previously just used a nut for this job but given that I was doing a number of screws I thought a dedicated tool would make sense.



Here's the end results although I may redo one of them which I cut before making the filing plate and turned out a bit short.



Thursday, 17 July 2014

Gate modification

We recently agreed to look after a relative's dog for them and realised that we needed to make a few changes to accommodate the dog safely. One of these was making the back garden gate so that it would not be easily jumped over.

I had difficulty removing the screws holding the hinges. The gatepost was not actually attached to the ground simply screwed into the fence so I remove the gate and post together.



I ended up drilling out the screws as they could not be shifted, even after repeat soakings in WD40. We'd decided to replace the gatepost with a taller one. This turned out to be a good choice as the post was pretty much rotten.



I dug a hole for the new post and used a broken crowbar and a bolster to chip through 4 inches of concrete. I don't recommend doing it this way as I managed to hit my hand with the hammer a few times. SDS drills don't cost much so next time I'll get myself one of those.



The new post was concreted in using some concrete I'd had left over from another job. This was not sufficient so I topped it up with some postcrete.





The gate was extended using two 50mm "fence posts" a batten across the top and some willow screening. The old grot and paint was removed with a pressure washer.



The framework of the gate was sawn down to make space for the posts. I drilled and chiselled a mortise in the top of each post and simply slotted the cross bar in place. The uprights were then screwed to the frame of the gate.



The willow screening was then attached using some heavy duty U shaped staples. You need to be very careful with the willow as it's so easily broken. The final steps are to give the gate and gate post a coat of preservative and to screw the gate back onto the post.



Friday, 11 July 2014

Spacers

A simple but important part for the clock was the spaces that connect the two clock frames together. These were a simple machining job, brass rod was faced off and drilled with a 2.3mm drill. It was then parted off in 15mm lengths.

The parts were rechucked and the parting off pip was then faced off. Finally the parts tapped with a 3mm through tap. The same technique of tapping in the 4 jaw chuck as used for the bush was used for the spacers. A pipe cleaner was used to clean out the threads before testing with the brass screws.



When assembling I found one of the threads was a bit tight so I ran the tap through it a couple more times. I discovered that a large tap wrench is a good holder for small round part.



Monday, 7 July 2014

CapSense Switches

As a little side project, I've been looking at some capacitive touch switches and their suitability for workshop projects. Element14 and Cypress Semiconductors kindly provided me with an evaluation board for the CapSense MBR3 switches as part of the Element14 roadtest programme.



As preparation for my roadtest report I've been writing up some blog posts on what I've discovered so far.



Tuesday, 24 June 2014

Small screwed bush

The next component to machine was one I like to call the "Top Hat". It fulfuls two purposes, it holds the clock mechanism to the face of the clock and it acts as a bush to support the spindles that drive the hands of the clock. I made a special clock opening tool to remove the existing one with the intent to re-use it. However it had an uknown thread on it and rather than go to the effort of working out what that was and then trying to buy a suitable tap set I decided to remake it.

Before I could start I chiseled the back of the clock to fit my new plates. I then had a look at my taps and an 8mm x 1.25 seemed the most appropriate. The plate had already been drilled and the brass was easy to tap.



I selected a bronze bar as I had some in stock. I started by facing the bar and drilling the hole. I then turned the the outer diameter down to 7.5mm on the lathe. I estimate this size based on measuring the tap as I did not have a suitable chart to hand. That's definately a mini project to source and print the data as a quick google failed to find the information. When it came to cutting the thread I used a 4 jaw chuck to securely hold the part and held that in the vice.



I did not really think out my machining sequence and after a near disaster I ended up having to saw the bar to length and file the head. However the end results turned out ok.



Here's the part in for a test fitting. I still have to cut the slot so it can be screwed in from the front. I will likely do that with a cutoff disk in my mini-drill but I might have a practice first on some scrap.



Tuesday, 17 June 2014

More clock shafts

After my previous success drilling a tiny but deep hole through some brass rod, I got thinking about how to machine the outsides. Referring back to my diagram the idea was to take a 4mm rod and machine most of it down to 2mm.



But on reflection this seemed like a bad idea so I decided instead to start with a thinner rod and add a bush to mount the gear wheel. I found some 2.4mm copper coated welding rod. I initially tried machining the copper coating but the rod was bending in the lathe and did not produce a good finish. However I discovered that the soft copper coating was quite thin and was easily removed when polished with some emery cloth.

A brass bush was drilled and turned so that it was a tight fit on the welding rod and also a good fit for the plastic gear.

Here's the redesigned shafts, the lengths have still to be determined.



Thursday, 12 June 2014

Pepper's Ghost

A few weeks back my 3 year old daughter gained a "Sooty" magic wand on the front of a magazine and has been trying to make things appear and disappear ever since. To help her "magic things" I was thinking about self working tricks. Initially I thought about some high tech solutions such as something that would respond to 3 taps of the wand in a similar manner to this secret knock detector.

However, I then remembered the old "Pepper's Ghost" trick which is an optical illusion which can make people appear and disappear simply by changing the lights. I borrowed some ideas Übernotes from to build one.



We created the effect by painting the inside of an old teabox with black poster paint. When it was dry a door was cut in the front and a flap in the top. we also added part of a fahita box for a roof.



After a quick trip down the workshop to cut a piece of perspex, we added that in with some whitetack. Finally a figure was added on the right of the box.



All that was left was to shine a torch through the hole in the top. Here's the effect in action.


Workshop Practice Series