Member postings for Russell Eberhardt

... and physics!

Russell.

Agreed, and the more turns the better such as the secondary of a microwave oven transformer. I don't think anyone here has suggested using one with the primary still connected to the mains. I would hope that anyone on this forum would have more sense.

Russell.

BTW., can anyone explain the theory behind these little permanent magnet with holes demagnetisers?  I don't see how they can work.

Edited By Russell Eberhardt on 07/07/2013 11:04:26

I haven't measured one but connecting the secondary to the mains will result in a lower current due to the higher inductance while producing a stronger magnetic field than the primary at the same current. Thus it will reduce the power dissipated in any current limiting resistor.

A microwave oven transformer only produces dangerous voltages if the primary is connected to the mains.

Russell.

The emails informing us that a new digital issue has arrived are still telling us to click on a non-existant menu item!

Russell.

Assuming that you bought it as a private individual and not as a business you have up to 6 years to raise problems with him under the sale of goods act. You are entitled to a product which is fit for purpose and the supplier should rectify it at his expence including postage.

Russell.

Note that, as the bearings heat up, the spindle expands so it's best to make any adjustments after it has run for over half an hour. The instructions for my lathe (not a Colchester) suggest adjusting until the end-float is reduced to zero and then tightening the adjusting nut a further 1/16 turn. Of course that will depend on the pitch of the adjusting nut thread.

Russell.

Note that, as the bearings heat up, the spindle expands so it's best to make any adjustments after it has run for over half an hour. The instructions for my lathe (not a Colchester) suggest adjusting until the end-float is reduced to zero and then tightening the adjusting nut a further 1/16 turn. Of course that will depend on the pitch of the adjusting nut thread.

Russell.

Now then, just where did I put my violin

You going busking?

Russell.

Well, if that comes to pass I shall be very annoyed having recently thinned out my collection of back issues knowing that they will remain available on line. I'll have to seriously reconsider my subscription when renewal time comes around being a pensioner on a limited budget

Russell.

Yes, I went on to them later. Much easier to edit your programs, just swap a few cards. It was a b****r when you dropped a big stack of them though!

Russell.

Just received an email from MyTimeMedia to say that the latest Digital Issue had arrived. It said,"If you are viewing via a PC, once you have logged in using your username and password, go to the My Account box and click on Digital Issues."

I went to "My Account" only to find that the "Digital Issues" entry had disappeared! After some time checking that my subscription was up to date I discovered that the "Digital Issues" had been replaced by "Online Archives".

Why change it? If it's changed then it should be changed in all references to it in emails etc. It seems to be another case of the left hand not knowing what the right hand is doing

Russell.

I expect I'll be shot down in flames by the boiler experts but:

The safety valve on these should be set to 15 psi. So for safety let's assume it can go to 30 psi. At that pressure water boils at 135 C so ordinary soft solder should be adequate.

Russell.

Line printers? New fangled devices! I used to feed the punched tape output from my programs into a Teletype machine, a sort of punched tape driven typewriter

Russell.

Every scientist/engineer relies on the discoveries of their predecessors. It's impossible to mention them all in a programme like that.

BTW. Hans Oersted discovered electro-magnetism before Faraday.

Russell.

You can also use lost PLA rather than lost wax casting. Good video here.

Russell.

Sounds like the stencils we used to use with a typewriter to print our catalogeus back in the seventies.

Russell.

You might find this useful: **LINK**

Russell.

You need to check the "leveling" ie., twist in the bed. Google "Rollie's Dad's method" for a straightforward explanation.

Russell.

An expensive RepRap variant compared to this for example.

Russell.