Member postings for Brian O'Connor

Thank you, John and Andrew, very reassuring. I now feel confident to raid the piggy bank and give myself a Christmas present of a range of carbide 3-flute cutters.

Brian

Thanks for all your responses chaps, but I'm still not clear what disadvantages there are, if any, of ditching all my old and blunt 2 and 4 flute cutters and using only centre cutting 3-flute ones (which I won't be able to resharpen) from now on.

Brian

I have quite a large collection of milling cutters, both two and four flute, that are blunt or at least well past their best. I also have a few three-flute carbide cutters which I find stay sharp for much longer. I have no means of sharpening the cutters so my question is this: can I replace all my two and four flute cutters with carbide three-flute centre-cutting cutters or are there some circumstances where a two-flute or four-flute cutter would be advantageous? I am particularly keen to get rid of the two-flute cutters as I find that even with a fairly substantial mill (VMC) and everything locked down I still get appreciable vibration when using the larger sizes.

Regards, Brian

The calibration tool is just a small 'C' spanner. the small projection of which engages in a small hole at the back of the barrel. If you can't get the correct tool it should be a simple matter to make something tha would do the job.

B

Yes, it has a ratchet. There is a simple procedure for aligning the two readouts. When I set mine to zero, using the ratchet, both readouts read exactly zero. I highly recommend it.

B

Curses, my link didn't come out as **LIMK**. There must be an istruction for doing so somewhere but I haven't been able to find it.

B

I have one of these:

http://www.mitutoyo.co.uk/small-tool-instruments-and-data-management/micrometers/193-111

As you can see it has mechanical digits, so no battery, and it also has the vernier scale as a cross check on accuracy.

Brian

To all of you stargazers out there who don't know of it already, there is a website called Astronomy Picture of the Day (search APOD on Google). As its name suggests, each day there is an astronomy or atmosphere related picture accompanied by a commentary provided by an expert. I have used it as my home page on Firefox for many years and it has taught me a lot, or at least it would have done if I could have remembered all of it.

B

Neil,

I was at Cranwell from August 1950 until November 1952, when the school moved to RAF Locking. I don't recall an instructor named Wyatt but then I'm not sure I can recall any of their names, it was such a long time ago.

B

No Ian, I learnt about Eccles-Jordan flip-flops as an RAF apprentice at No 1 Radio School, Cranwell. It was many years later that I first worked on digital computers, up till then they had all been analogue. My first bit of programming was on a GP4-B, made by Link to drive their flight simulators. It had a drum instruction memory and 8K of core random access memory. 8K!!!

B

Fitted a dash-cam to my car today and am amazed at the quality of the HD video from such a tiny camera. But what really blows my mind is the physical size of memory these days, the 32Gb memory in the camera is the size of a fingernail. When I first started in electronics a single bit of memory was formed by a double triode connected as an Eccles-Jordan flip-flop. To make a 32Gb memory out of these, ignoring all of the ancillary circuits, would require 4,800,000,000 amps at 12v just for the heaters, which would probably make my battery struggle a bit.

B

Anyone contemplating buying a Mitutoyo caliper should be aware that there are many fakes out there. If you Google 'fake Mitutoyo calipers' you will fiind several sites describing the differences between genuine and fake calipers. Although there are several differences the easiest way of telling them apart is to look at the digits on the inch scale. The genuine one has four full size digits after the decimal point whereas the fake one has a half size last digit.

Brian

David,

I too have the MES abrasive band machine, one of my most used tools, a real metal shifter. You can get Norton aluminium oxide belts 50 x 1000 (which fit the machine) in various grades from

www.bndabrasives.co.uk

Regards,

Brian

I bought a VMC from Warco and asked them to install it in an interior room of my house. Access to this room was only just possible, involving making a ramp up to the front door, skirting around the bottom of the stairs and then in through an interior door. Because of the narrowness ot the door the table had previously been removed. This had all been planned for and I had had to wait for the availability of a mechanic to remove the table and then refit it once the mill was in its final resting place. It all went fairly smoothly and before leaving the mechanic checked that everything was in order following his refitting of the table. Satisfied customer.

Roger, Jo is right. The circuit I sent you is an exact copy of the one supplied by Transwave in their pendants. As Jo says, all you need to do is put another normally on push button in the +24v line from the inverter in series with the existing Off button.

Brian

Ordinary sea water will soften iron given long enough. I recovered some (I think 16th century) cannon balls off the sea floor at Fowey and you could cut them with a knife. They eventually just fell apart.

Brian

Neil,

I have sent you the circuit diagram of my Jaguar remote pendant via email. The relay is there as a safety device. When the Start button is pressed the relay operates and holds itself on, maintaining the power to the machine. If power is lost the relay drops out and the machine can only be started again once power is restored by pressing the Start button. Without the relay, if power is lost and the operator forgets to switch off, then when power is restored the machine will start on its own, just as one's grandson is saying "What's that bit for, Grandad?"

This crappy website strikes again. I have tried opening the image in my above post and find that I am unable to, so presumably no-one else can either. I put it there by pasting the image from the clipboard. When creating the posting the only way that I could view what I had pasted was to click on the icon, select copy and then paste into a blank document, but once posted clicking on it has no effect.

Does anyone know how to get round the problem? I have the diagram as a Word document and as a PDF. If all else fails I could always send it to anyone interested via a PM.

Brian

I'm afraid that I'm unable to help Len P, but for Neil here is the circuit diagram of the remote pendant that I made for my Jaguar Cub VFD. In addition to the usual switches and a 5K pot you will need a 24v single-pole relay.

Come to think of it, perhaps Len can rig up something similar for his VFD.

Brian

I have Transwave ‘Cub’ VFDs on both my S7 and VMC mill and can assure Paul that torque is maintained right down to the lowest speeds. I regularly run mine from up to 100Hz (double speed) down to15Hz (less than one third speed - wonderful for large radius fly-cutting!) and even at the lowest speeds I cannot stop the chuck with my hand.

They will actually run at 10Hz, but not for long. The problem is that as frequency is reduced the reactance of the windings (their resistance to AC current) reduces proportionally and so the current increases until the VFD finally says “enough is enough” and cuts out. Another problem is that at low speeds, the increased current along with the reduced cooling from the motor fan results in motor temperature rising. Luckily, for most model engineering tasks the motor is just ambling along and I have never found it a problem, but it is obviously something to keep an eye on.

Brian