Member postings for Peter Cook 6

I use a cheap tyre depth guage as a simple quill DRO on my SX1LP. Apparently it is a capacitance based measuring device.

It works very well - as long as I keep my fingers away from it. If I switch it on or zero it using my fingers I get 0.03-0.05mm "jitter" on the display. Zero it with a non conducting object ( plastic T slot cleaner usually) and all is well.

Take the device off the mill and it behaves perfectly as does another similar unit I use for measuring the depth of holes.

I suspect the issue is a capacitance effect between me and the ground plane provided by the big lump of iron to which it is screwed.

Can anyone explain in a bit more detail how these things work, and make any suggestions as to how I might screen the problem. A bit of brass or plastic between the device and the mill head makes no difference.

I'm not sure. I suspect an awful lot of the 3D printers bought are being used to print things from the internet (Thingverse, Yeggi, Instructibles etc.). The learning curve for 3D design is steep, and the risks inherent in metal cutting are also far higher than for 3D printers.

Be careful what you wish for. If 3D metal cutting tools become "cheap" and mass market - watch out for the H&S brigade to be close behind.

The other issue that I suspect will get in the way is tool changing. Commercial CNC setups have some very sophisticated tool changing capabilities, difficult to replicate at any reasonable cost. what proportion of hobby lathes have a capstan turret? How may of them could be automated?

On machines designed for drilling (most small mills and drills) there are two ways to lower the drill bit towards the work. One is to move the whole head down, the second is usually a rack and pinion or similar arrangement that moves the spindle holding the drill bit relative to the head. This parts that move within the head and allow this is known as the quill. If a machine does mot have a quill, then the only way to drill with it is to move the whole head down to feed the drill into the work.

The Sherline & Taig small mills don't have a quill, and to lower the drill into the work you would need to wind the vertical (Z axis) leadscrew down. Accurate in terms of Z position for milling, but slow and cumbersome for hole drilling. You can use a sensitive drilling attachment, but that limits the size of drill (the Sherline unit has a maximum of 4mm).

Using a lathe with a vertical slide for milling doesn't mean turning the work. You mount the workpiece on a vertical slide fitted to the saddle of the lathe, and put the milling cutter in the lathe chuck (use a collet). So the work stays still and the lathe motor rotates the cutter. It's like a small mill laid on its back. If you search "vertical slide" on Warco's site you will see an example fitted to their version of the small lathe.

Two points.

As far as I am aware either the Taig nor the Sherline mills have quills for drilling. Both rely on the Z-axis leadscrew for such motion, and that makes drilling on them a little tedious I suspect. That's one reason I bought an SX1LP rather than a Taig (I have a Taig lathe) or Sherline mill.

If most of the work you want to do is small scale and milling is more important than drilling, have you thought about a small lathe with a vertical slide. I have done small scale milling on my Taig lathe before getting the SX1LP, and would suspect that it is at least as good at milling as the small Proxxon. It is also considerably lighter and easier to put away than any capable mill. Axminster do the C0 which weighs 13kg, the C2 weighs 37kg. My Taig weighs about the same as a C0 . It has the side benefit that you also get a lathe!!

Not historian, but I have a general interest in (and too many!) clocks.

I suspect you will not find a definitive answer. Features such as the flat spring and catch detent clicks on clocks will have varied between makers over a long period of time. Changes will have started in the higher end clocks, and only very gradually percolated to cheaper or more provincial makers.

I would guess that the first makers to use the flat spring would be those that made 8 day and/or fusee clocks - both of which typically use that style of click. They would have had the parts available/designed and consequently used them on any higher end 30 hour clocks. I would expect the first ones to be made in the early 1700's.

30 hour clocks with circular springs were still being made into the 1800's. I recently cleaned my French lantern 30 hour clock which dates to 1820, and that uses circular clicks. They would probably have stopped being made only when factory made mass production clocks became commonly available in the middle of the 19th century.

So say between 1710 and 1850 would be the changeover period.

You could try asking on the NAWCC forum (you don't need to be a member to sig up), or one of the clock forums on the internet.

Edited By Peter Cook 6 on 30/03/2021 14:17:42

Could you not fill the boss with a bit of casting material - plaster of Paris, silicone rubber or casting resin - after a light coat of the appropriate release agent.

Let it set, pull out the casting, and you have an exact copy of the thing you want to make.

Clock dial engraving is filled with black engravers wax ( a.k.a elephant wax). That might work OK. It is applied by heating the engraved Item to melt the wax into the engravings. Squeegee excess wax off using a knife while soft. let it harden then remove the film of wax left using wire wool or fine wet and dry. Then polish.

A new steel rule might be cheaper and far quicker

By watchmaking standards those are fairly big. If you look up arbor turning, or arbor repivoting you might get some ideas about the tricks and techniques used, but I think Howards advice is correct.

And it's not just cars!!

After the dishwasher failed recently, I went looking for a new one. Guess what they all connect to the interweb and are designed to allow you to control them via a mobile phone "app". WHY?

If I'm not standing by the dishwasher I can't put stuff in or take it out. I only start it when it's full, so why would I want to fill it, go away and then start it using my mobile phone sometime later?

Assuming the table has a central hole (mine has an MT2 taper), put a centre in the hole. Put another centre in the chuck and line up the points - use a magnifier to get it accurate on x & y.

Mount the work centrally on the table using the centre in the chuck to centre the work - without moving the table.

Now the work and table are all centred. move the x (or y) axis by the pitch circle radius. The centre of the chuck is now on the PCD. Rotating the table will now allow the chuck to trace out the PCD.

Does it buzz on load?

It sounds like you are getting a switching transient on the output which may be an artefact of the fact that there is no load on the triacs. The spec sheets call for a minimum current of 250ma.

If you have an oscilloscope available have a look at the output of the relay.

If it doesn't buzz on load, try wiring an incandescent lamp (60w will probably do) across the output to provide a baseload.

Edited By Peter Cook 6 on 25/03/2021 18:51:52

Scheibe SF-25 Falke - Touring motor glider

I was thinking of the second kind. I used a green (silicon carbide?) one the other day to take the point off an M4 HSS tap, so 1mm mild steel is going to be no problem. You might want something to dress the wheel with to keep it square, but a bit of HSS steel would probably do although at the price I would be tempted to swap the wheel if it showed signs of wear.

In answer to Q1 I was thinking of the small 20mm diameter grinding wheels that fit on a mandrel and are used in Dremmel tools. At the cheap end 8 wheels plus a suitable 3.17mm mandrel cost £3.45 from a well known auction site. Better ones are no doubt available elsewhere.

For Q2, for the volume you are planning to make I was thinking of making the table from a small piece of Plywood, MDF or other suitable smooth material that was big enough to cover the base of the proxxon. Glue or screw a strip of thin timber or plastic (say 10mm wide & 5mm thick) to that base. Then place it on the proxxon base and clamp it down (depends on what clamping arrangement the Proxxon has) at the correct distance from the grinding wheel.

Put a grinding wheel in the proxxon drill. Set the (a) fence at 90 degrees to where you have it now and the correct distance from the wheel.

With the grinding wheel flat you could do the back edge, Tilt the wheel to 45 degrees reset the distance to the fence and grind the chamfer. You should have enough power for 1mm steel sheet.

Edited By Peter Cook 6 on 22/03/2021 23:36:14

I considered one for my workshop which has a wooden floor on bearers. I went with a concrete slab because the level of precision (flatness and level) needed in the surface on which the plastic stands needs to be very high if you want a long term stable base to put the bearers on. The one I looked at recommended a couple of inches of well tamped and carefully levelled sand on top of the soil. Any subsidence in the underlying soil will also cause problems.

I suspected getting the base level and flat would not be worth the effort. A concrete slab only needs the underlying surface to be roughly level, the shuttering round the edge so far easier to get level. Then the concrete is fairly self levelling.

If you do use a wooden floor get one constructed from treated timber.

My elf likes the very small taper pins used in clocks. (0.2mm diameter and 4-5mm long). Once they squirt out of the tweezers I can rarely find them UNTIL I have searched hard, given up, made a new one and fitted it. At that point the elf returns the missing pin in an entirely obvious place.

Edited By Peter Cook 6 on 20/03/2021 12:50:08

My watchmakers lathe is driven by a simple sewing machine "universal" motor.

I implemented a speed controller to replace the crude foot switch (3 speeds and off*) using a standard 400W lighting dimmer switch. It was very cheap from fleabay and works fine.

* The three speeds were full power, half wave rectified and half wave rectified with series resistor. The pedal applied power then  shorted out (in sequence) the resistor then the diode.

Edited By Peter Cook 6 on 19/03/2021 13:13:30

A really cheap 25mm travel DRO can be created from a digital tyre guage.

This is one in use on my SX1. Screwed to the holes for the guard. Connection to the quill is a tiny neodymium magnet glued to the end of a plastic rod. Works well.

That's definitely one reason. The bells in our church park mouth down so that the clock hammers can hit them when its chimes and strikes. There are wires to pull the hammers off the bells before rotating them to mouth up at the start of ringing.