firing up woes

[runner42]

Jul 24, 2024 21:55:34 GMT jma1009 said:

Hi Brian,

For what it is worth here are my thoughts based on experience.

A decent electric blower fan ought to be able to get the water boiling and the safety valves lifting at working pressure on firstly charcoal soaked in paraffin (my preference is to use BBQ lighter fuel instead of paraffin) then charcoal alone. [It is/was a well known ‘trick’ in the UK IMLEC to reduce initial coal consumption].

So, from my perspective, you ought to be able to get to working pressure on just charcoal. So the quality of coal ought not initially come into the matter.

[The above IMLEC example is not what was my usual practice]

I found electric blowers very dependent on the voltage. 2 car batteries (can’t remember when in series or parallel) would make all the difference between getting steam up in 6 minutes compared to say 15 minutes!

The electric blower ought to be able to suck off the shovel a load of charcoal or small coal.

Try running your electric blower at 24 volts instead of 12 volts.

Cheers,
Julian

Hi Julian,

thanks for your advice, however you have provided the what but not the how. Firstly, running a 12 volt motor on 24 volts is not a good idea, I assume your motor is rated at 24 volts. The suck off test you describe  is remarkable and probably dependent on the speed of the motor and the size and number of the fan blades, so I am wondering what insight you can give into this part of your blower's design?

Brian

[jma1009]

Hi Brian,

From my time in the IWMES, Smiths car fan heaters were used. I had 2 of this type. Both had plastic fans within a aluminium body with the electric motor on top. They would only create a decent and effective draw on the fire if run at 24 volts.

Obviously, after years of use, the plastic fans would degrade and the motors less effective. Running them off a 12 volt car battery produced a similar effect to that which you described.

The IWMES had a control box in “No.1 shed” controlling the voltage to the steaming bays and this had 12 volts or 24 volts supply.

Other clubs such as Beech Hurst and Cardiff used an air compressor with a pipe down the chimney with a ‘u’ bend above the blast pipe - and these were more reliable.

I think if I were to make a new electric blower then I would ensure that the electric motor was not affected by the heat of the exhaust, and a proper fan out of metal blades in a metal casing used.

That said, if a club track had a compressor, I would use it as above for Beech Hurst or Cardiff.

Some might be surprised that steam can be raised on a copper boiler in 6 minutes. That is with 3.5”g and medium sized 5”g locos.

I am aware that Polly supplied electric blowers rated at 12 volts with a motor raised off the fan; a friend had one - but it wasn’t as effective as might be thought.

[chris vine]

I have a polly fan. Well made but I replaced the motor with one from a defunct makita cordless drill. Much better!
I run it off an old car battery charger and by choosing 6 or 12 volts and slow or fast charge settings I have plenty of control of the draught.
Cost nothing too!!
Chris

[steamer5]

Hi Brian,
Old school vacuum cleaners have aluminum fans in them…. I’m cleaning up dads & found 3 or 4 he had squirreled away for replacements if required…. Don’t think it’s going to be an issue! As I now have 2 blowers! Oh plus a 1” air mover. Both the blowers have X car fan heater blowers…. we had a fireman in the club & any excuses to play with there car cutting up toys on wrecks was jumped at to get 5he blowers out!

Cheers Kerrin

[runner42]

This is the end of my ME life. Yesterday I was trying to emulate Julian's suck off test and tried running the motor without the speed control device, after modifying it by adding a chunk of donut steel around the motor to keep it cool. The result was that the blower rotated whilst sitting on the chimney which caused the leads connected to the motor being twisted around due to the large rotation force being applied. I picked it up off the chimney whilst it was still running. This was a major mistake as I tried to turn it 90 degrees to unravel the leads the gyro effect caused it to slip from my grasp and my left hand index finger hit the rotating blades with the result that it was a bloody mess and the top of the finger is pointing down in an abnormal manner. At the A&E department of the QEH in Adelaide I was X rayed, photographed, given anti tetanus injection, a drip containing strong antibiotics, stitched up bandaged with an arm sling and sent home. Tomorrow, I have to attend the hospital for corrective surgery to repair severed tendons.  

My wife is very unhappy since she fears my shed time and thinks that at my age I am becoming more accident prone. So I am giving up this adventure in ME and reverting to my earlier interest in painting pictures as a pass time.

Brian

[steamer5]

Hi Brian,
Don’t give up! Take it as a learning experience, you sure as hell won’t try that again!
My dad took the end off his thumb while trying to single handed re-rail his loco, in his late 70’s, he only passed a couple of months back, he enjoyed every day in his workshop since retirement some 37 years.

Cheers Kerrin

PS… next version of the blower to have fully enclosed fan?

[flyingfox]

Brian, I was sad to hear about your mishap, and hope it is soon resolved.
as you now know, operating a fan without a guard is dangerous, but seems to be done all the time, which is something I advocated in an article in ME entitled "Why are they called blowers when they suck". I also advocate handles for removal.
Perhaps a read of that article will renew you confidence and cheer up "She who must be obeyed"
Regards
Brian B

[dhamblin]

Sorry to hear that Brian, hopefully the surgery does the job.

Take time to recover but please don't give up on the hobby. Use the time to think how the incident happened and redesign the blower to both prevent it from happening again and perform better. Humans are at their best in adversity - use it to your advantage. Paper and pencils are cheap so rough out as many redesign sketches as you like to test ideas/theories.

All the best,

Dan

[jma1009]

Hi Brian,

My very best wishes to you and for a speedy recovery from what must have been a nasty accident and very painful and shocking.

Cheers,

Julian

[runner42]

Thanks for your good wishes.

After a micro surgery operation which lasted 1 1/2 hrs I have had a another visit to the hospital and two more are scheduled. They like to ensure that their handiwork is not jeopardised. The special stitches that keep the tendons in situ are special and stay in longer than others. I had multiple fractures, all this in just the end part of the finger.

My home made blower was a problem due to the impeller being fabricated with galvanised sheet steel, which consisted of a round plate with six fan blades rivetted to the plate. This method caused slight variations in symmetry which when operated at 10,000 rpm plus caused significant vibrations to occur. Although I tried to balance the impeller it was never quite good enough for such high speed running.  

What is the relationship between fan speed and axial flow? Intuitively, I think that the relationship is not linear, i.e. doubling the rpm does not double the axial flow. Like a lot of things there is science behind it, not quite rocket science but complex enough for a PhD thesis.

Brian

[uuu]

I thought I'd look it up - this is probably not quite the right one but.... en.wikipedia.org/wiki/Axial_fan_design

I don't think I'm going to work through it. Life's too short.

Wilf

[tenor]

With a square law curve of resistance through grate,fire and tubes a rotodynamic fan will give a very nearly linear response of flow to rpm. The slight error is due to efficiency tending to increase slightly with speed.

Martin
35 years in pumps & fluid dynamics.

P.s. Hope the digit continues to heal. We all have a few battle scars from stupid mistakes. Never ask me for advice on how to traverse a speed bump on a 4" Burrell............

[JonL]

Jul 28, 2024 6:57:39 GMT flyingfox said:

Brian, I was sad to hear about your mishap, and hope it is soon resolved.
as you now know, operating a fan without a guard is dangerous, but seems to be done all the time, which is something I advocated in an article in ME entitled "Why are they called blowers when they suck". I also advocate handles for removal.
Perhaps a read of that article will renew you confidence and cheer up "She who must be obeyed"
Regards
Brian B

I've been meaning to add a wooden handle to mine for a while (so I don't have to keep wrapping my hand in my hat!). You've just encouraged me to finish the job.