Member postings for Ed Dinning 1

Transwave or similar switched capacitor units are probably your best bet. Some of these types work best with a pony motor (runs unloaded)/ balancer in circuit.

Possibly the lowest cost option too.

Note that they will nor run VFD's or any electronic gubbins, great with just a simple motor

Ed

Hi Gents, thanks for the replies. I didn't think I had had the sander that long, but time passes.

Son in Law killed it initially by thinking that the harder you press down the better it will sand. Then keeping it running for an hour or more !!!

I've not got a growler but all the other s/c armature coil symptoms are there, fireball comm etc

Cheers, Ed

Hi Folks, has anyone dealt with this company recently?

Plenty of ads on ebay for spare brushes etc, but trying yo contact them to get an armature for this belt sander and I get number unobtainable (01302 721791)

Any assistance appreciated

Ed

Hi Folks, a good article and resistivity is easy to measure, then getting to the correct alloy, but beware of second order effects such as surface texture and colour.

That set it is a very good engineering guide

Ed

Looks like the Ambrosia factory is suitably situated in the Yorkshire "rhubarb triangle"

Ed

Hi Folks, I seem to have prompted a lively discussion on these topics!

Summarising, we are engineers , used to thinking in a logical way and finding a solution to problems.

There is an Engineering saying, that "dross rises to the surface", from the preceding discussions I conclude that this has happened in public life; politicians of all shades, and their political advisors are guilty of this. From personal experience the higher echelons of the civil service are similarly mired.

It is a great pity there are not more Engineers going into public service, finance and the law or should that be justice?

Think carefully when you next cast your vote, but as Churchill said "Democracy is the worst system, apart from all the others!

Ed

Hi Folks, withe the current load noises over the pollution caused by fossil fuels and why we should, or should not use our own resources, it seem to be forgotten that only about 25% is converted to fuel for all forms of transport.

What will we do for lube oil?

Most of the rest is PETRO chemicals and used as feedstocks for plastics and a variety of other uses.

Coal can be used as a cheap form of carbon much more easily than "carbon capture"

A final thought about Ethanol in fuel:

Ethanol is much lower mass than normal petrol or diesel

The burning reaction is based on mass consumed

We by fuel by volume

So 1 L of Ethanol fuel weighs less than normal fuel and gives you less MPG; it is cheaper, but I doubt if it is proportionally so

Ed

Hi, there were a couple of designs in the 9/10 set and supermodels leaflets associated with Meccano in the 40's/ 50's.

These may be available on line

Ed

Hi Bernard, what sort of machine do you want the chuck to fit onto?

There may be a standard one available

Cheers Ed Dinning

The green snap lid boxes that the tablets/ small sachets of washing machine detergent come in are pretty robust and reasonably large.

One of the many sorts of boxes I use; these are mainly for nails and larger screws.

Photocopier boxes (A4 size ) are useful for my collection of electronic valves and larger, lighter stuff

Ed

Hi, a bit of an expensive option, but if you look at the RS ONline site they have Brushless DC motors (BLDC) and similar that will work on 6v as well as having a controller that allows speed control. Some of these units can easily top 18,000RPM

Ed

In a brushless machine the speed is set by the frequency of the driving waveform and the rotor locks to this frequency with a pretty high torque. On commercial machines this is often exploited for tight control of axis positioning. This causes motor heating and on those machines the motor is sized for it.

On a hobby machine there will not be so much "meat". Some of the energy will go into regen or freewheel diodes and some will still be lost in the motor windings.

Provided the speed is not taken from max to min with great rapidity there should be no problem, keep an eye on motor temps.

I always find it easier to turn the speed control up and down at starting and stopping, perhaps over about a second as it gives a smoother feel to things.

On older induction motors fitted with emergency stops it was the practice to inject DC into windings. This would give a PDQ stop and cause quite a lot of motor heating. A BLDC motor is a quite different beast

Ed

Hi Folks, modern irons with plated tips should not be filed.

Cleaning is don eon a damp sponge (not soaking) or the modern equivalent that looks like brass wool.

RS and others do a tip tinner/ cleaner paste in a small pot the was normally used about twice weekly in a production environment the gert the tip nicely bright after a lot of use (RS 507-8698)

Ed

Hi Liam, note that most of the threads will be Whit or BSF and you will need the appropriate spanners for them

Ed

Hi Folks, on a similar vein we needed to heat treat Ti at about 350C with a gas oven . As these were large pieces it was a large expensive oven and the Ti needed to be sheilded so that TiN would no form on the surface. This was a time consuming process, so we came up with the idea of passing a current through the Ti sheet; as Ti is quite resistive we needed about 3 to 5 volts at 300A.

An old high current mains transformer had its secondary rewound with 1.5 * .25 " Cu bar and connected to the Ti sheet by welding clamps. Heating under ceramic insulation took less than 10 mins with negligible TiN formation and aslo reduced the energy bill

Ed

Hi Gents, thanks for the inputs.

The application is a forced draught fan for a wood burning boiler.

Original equipment is a 250w cap run induction motor that is working well. It originally used an Italian made inverter as a 2 speed VFD.#This has died with no obvious faults and no way to get a schematic.

The PCB logo is (RD)² . It appears to have many more facilities for control than were needed, but no details of how to activate them so we can have full speed and about 1/2 speed,

I've since found Invertek drives and their Optidrive range has a single phase in, single phase out inverter for fan and pump use that can be configured as I need it, as well as many other features that I will never use.

Anyone familiar with this unit ?

Ed

Hi Gents, has anyone recommendations to make for the use of inverters on 230v. single phase, to run an induction motor(single phase, cap run, 230v); or have they successfully used them ?

Maker, supplier, likely price ?

A simple unit is all that is requires as the motor drives a fan and only 2 speeds are needed. One near max and the other about 1/2 speed.

Many thanks, Ed

Hi Steve, if you can get the electronic controller that went with this motor, many of your problems will be solved as it will give variable speed with a current limiting characteristic, so speed should not drop with load.

You will then need a fairly hefty mains to 24v DCpower supply unit.

Cheers, Ed

Hi, opaque or black plastic watering pipes will stop anything growing in the low water flows and the heat.

A header tank or resevoir and then a peristaltic pump for low flow rates, through chokes if necessary to equalise flows.

Ed

Hi Gents, I misread the original posting, possibly best way to proceed is to run the motor at about the proposed speed and see the output voltage. Depending on type LEDs often need about 1.5v per device. It should then be possible to see how many you can fit in a string. Several parallel strings could then be operated as they typically need about 10mA or so peer string.

Ed