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Member postings for Glyn Davies

Here is a list of all the postings Glyn Davies has made in our forums. Click on a thread name to jump to the thread.

Thread: Cutting a slot in a screwhead
30/07/2022 13:52:33

I mounted a cheap 3 jaw chuck to an angle plate and leave it permanently set up on my D-W miller. No DRO, so I turn a piece of scrap 1/4" rod to form a pip whose diameter equals the thickness of the slitting saw. Then align by eye. If using small countersunk Allen screws, I slot them to allow them to be removed if the hex socket becomes rounded.



Thread: LED lamp help please
11/07/2022 19:57:07

Thanks for the additional replies - I've learned a lot! In the short term, I've ordered some SR160 diodes to replace the BAT41s and as a longer term fix, have ordered from China the multipurpose charger circuit. When I get that, I'll connect a battery to the output and see if there's any voltage at the input. If there's none I can presumably ditch the blocking diodes altogether.

For interest, here's the lamp as first built running on propane:


And here's the LED conversion:


11/07/2022 00:31:17

Thanks for the replies. I had some LEDs and diodes spare so I used my power supply to test the actual resistance of the diode. With the voltage set to 5V (the max open circuit voltage of the solar cells), with no diode, the current is 67mA; with a diode in circuit, the voltage across the LED is 4.4V and the current is 45mA. With the voltage set at 3.6V and no diode, the current is 31mA. With a diode, the voltage across the LED is 3.0V and the current is 9mA. So by my reckoning, the diode resistance is .6/.045 = 13 ohm at 5V and .6/.009 = 66 ohm at 3.6V. I tried two diodes in parallel and the voltage and current were the same as with one diode.
I have no data sheet for the solar cells (off ebay) - is there a way of finding if there is a blocking diode in them without causing damage? The cells are 100mm x 172mm and are rated at 2W at 5V. I measured the 270K by putting my pocket multimeter across a diode.

10/07/2022 20:13:47

I have been asked to convert a propane eternal flame to solar powered LED. This is the set up I have built and it seems to be working well, with the batteries powering the LED as daylight fades.circuit.jpgMy question concerns the diodes. I just measured the forward resistance of a BAT41 diode at 270K ohms. I thought diodes were low resistance in the forward direction. Would the set up work better if I replaced a single diode with two or more diodes in parallel? Are there any other improvements that could be made to the circuit? My electronics knowledge is limited! Thanks.

Thread: Lidl Bench Grinder
04/05/2022 21:16:35

Lidl is currently selling 6" bench grinders for £21. These have a 200W 2980rpm induction (I think) motor, which is a bit weak for 6" grinding wheels, but I bought one with a view to re-purposing it. I removed the motor end caps and extracted the spindle and cut off both ends. I then turned the right hand end to 12mm and cut an M8 thread to take an angle grinding adapter.

The result is shown in the photos and allows accessories such as sanding discs or the thin cut off wheels to be mounted. These latter are useful for roughing out HSS lathe tools to be used for parting or screwcutting.

I extended the tool rest by drilling a couple of 3/16 holes in the original and clamping a piece of 2" x 1 1/2" x 1/16" plate to it. I then filled the holes using a stick welder, sticking the extension plate to the original rest.

I think the motor is a gem for the money - very quiet and smooth running and enough power to drive angle grinder tooling.


Thread: Gauge Ball Sets
11/02/2022 10:44:35

I found these gauge ball sets for sale:

gauge balls.jpg

They come in metric or imperial and contain pairs of balls up to 1" or 25mm diameter. Can anyone tell me what they are used for in industry? All I can think of is measuring internal cone angles or measuring dovetails.


Thread: Monocular lenses
08/12/2021 11:43:47

Thanks Michael, I'll give it a go.

08/12/2021 09:58:39

I just bought a nice compact 12X monocular off eBay. It cost £10 and offers quite good imagery but the body is plastic. I'm curious to know if the lenses are glass or plastic. Is there any way to tell, other than trying to scratch them? Thanks.

Thread: Metric Screwcutting on Super 7B with 127 Tooth gear
01/11/2021 12:05:12

I don't have a 127 tooth gear, but looking at my gearing spreadsheet and using the metric conversion set, with:

Tumbler stud - 30t

Gearbox input gear (gear X) - 127t

First stud driven - 60t

First stud driver - 80t

Gives exactly:

A1 - 1mm pitch

B1 - 0.5mm pitch

C1 - 0.25mm pitch

A4 - 0.8mm pitch

B4 - 0.4mm pitch

C4 - 0.2mm pitch.

The arrangement looks like it will fit the standard metric conversion banjo.

The standard metric conversion set using the 63t gear gives an error of .00125mm per 10mm of thread length in all the metric pitches.

Thread: Warco milling machine speeds
25/10/2021 20:51:08

On my 2017 VMC, this is the speed sticker on the belt guard:


This is the pulley arrangement:


This is the speed table I constructed having measured each speed with a tacho:


Thread: How to turn this bush
08/07/2021 10:46:44

I have reamed Delrin with a mild steel D bit reamer and it cut to size. I turned the reamer to size and put about a 1mm chamfer on the front end before milling it to a D form. I'd obviously ream the bore before turning the OD.

Thread: Machining Cylinder Head Chamber Roof - DIY or Shop Tool
01/07/2021 10:43:08

If I understand the task here, it's to produce some flat area in the chamber that is a defined distance from the top face of the cylinder head so as to provide a guide when using a mounted point on a flexible shaft grinder to fully profile the chamber. Why not set the depth on your pillar drill and use a small diameter end mill (~5mm) to create a number of spot faces in each chamber? Or just use a 5mm drill instead of the end mill.

If the valve seats are already cut, you could make a pair of dummy valves that protect the seats and sit in the seat at the correct depth to act as a further guide when grinding.

I still have my 1973 Vizard's guide to cylinder head modification from my 998cc Mini days and scanned the 1275 Midget template:

scan 01 jul 2021_1.jpg

Edited By Glyn Davies on 01/07/2021 10:46:59

Thread: Adept No 1 or Mal-adept?
06/05/2021 09:10:58

Here are pics of the No1:r0010040.jpg

adept advert.jpg

Thread: Digital Callipers - again
24/02/2021 16:52:52

I set up an experiment some time ago with my Aldi calliper where I powered it from an external 1.5v source so I could measure the current drawn. I forget the value of current (very small) but it was exactly the same whether the display was on or off.

Thread: Rufforth Metal Man
25/01/2021 12:04:04

Found this old card, could be your man:


Thread: Air Compressor Warning
25/01/2021 09:46:24

Since I have a 150psi, 50 litre compressor under my bench, this post gave me a bit of a fright. Mine's an Airpower similar to that shown in one of the later videos. At 3mm wall thickness, the hoop stress in the tank at 10 bar is 44MPa, giving a 5x safety factor against the 2% proof stress value for MS. And way below the fatigue limit for MS. Even at 2mm thickness, the SF is still about 3.5.

In the OP's video, he thinks the failure initiated at a seam, not where the worst rust from condensate was, and I saw that the delivery pipe from the pump seemed to have blown off the unloader valve. So I wonder if the failure was due to overpressure.

Thread: Warco VMC mill wiring diagram
21/01/2021 16:12:34

This is the wiring diagram for my 2018 VMC:

wiring diagram.jpg

Thread: Myyford gearbox strip down
15/01/2021 22:01:36

These gearboxes are so beautifully made that I don't think any part needs much force to dismantle. Put the inner shaft with the long spline back and refit the input gear and use that gear to stop the pinned gear rotating. I think the pin In the gear cluster shaft will knock out easily.

15/01/2021 20:50:49

The taper pin seems to be in a through hole, not a blind one, so why can't you drift it out from the small end? Maybe take out the gear cluster shaft with the long key in it from the right hand end to get some more room. They put it together, so it must come apart!

Thread: Bending small copper tube
29/10/2020 13:03:04

I also needed to make some tight bends close together on 5/32 tube. I bought the Dubro and its former wheel groove diameter is 11mm, so 5.5 mm +5/64" cl radius. The disadvantages of the Dubro are that it needs 12mm or so of straight tube before and after the bend and its plastic body means that it will only bend annealed tube.


I then wondered how I could make the simplest possible tool and came up with this:



Took half and hour to make and although restricted to 90 degree bends, it works a treat on un-annealed tube. Groove diameter of the former is 7.5mm. Make sure the groove is deeper than half the diameter of the tube so the tube is positively prevented from going oval during bending and the groove in the clamping block needs to be shallow enough that the tube is solidly clamped when in the vice.

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