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Member postings for Nigel (egi)

Here is a list of all the postings Nigel (egi) has made in our forums. Click on a thread name to jump to the thread.

Thread: The sneering detractors
23/05/2020 16:54:56

I've been a model maker for over 40 years, taught by my dad, but never formally taught engineering. I use the wrong words and I'm sure there are some who would cringe if they saw me in my workshop, but what does it matter. My days in the workshop calm my mind and relax me after some long and difficult weeks at work. This is a hobby that brings me peace. I make models, I have fun researching and sketching ideas for new models to make.

It's very easy to criticise someone else, it's much harder to add worthy comments that help and encourage more people to enjoy this wonderful hobby.

My dad always said "it's very easy to break something, but if you make models it is unlikely you will break anything as you will understand what it takes to create" (words as I remember them and not as said as he died nearly 20 years ago).

Let's help the next generation, Nigel

Thread: 5 Cylinder Rotary Air Engine
23/05/2020 16:39:13

With lockdown I've been running more of my old engines and thought this was rather fun, the 5 cylinder rotary runs on what is effectively not much more than a fishtank pump, in this case it's the air pump for the lumbar support in a car seat.

I need to create some drawings as it runs so well.

Thread: 1/20th Scale Traction Engine
09/05/2020 20:37:49

The rims now have the right cross-section

traction engine front wheel rims

The front wheels have a single bead and the spokes crossover side to side. Will be making the hub and spokes next, the hubs will be made from PB or brass at the front as they will also be bearings for the front axle.

27/04/2020 20:00:56

I cut the front wheel rims out of a piece of 70mm diameter mild steel

However, they just looked rather large compared to the rear wheels, some this is down to the fact that these are the roughed out rims and when I machine the outer rim to the proper section they will look much lighter.

Overlaid on the image that I'm using to design the traction engine from and they perfectly just cover the front wheel rims.

I'm spending too many hours just looking at the parts I've made so far.....

Thread: Anyone Got a Warco WM240B?
23/04/2020 20:27:39

So I bought a Soba 3-jaw chuck that is meant to be front mounted, didn't have access to long caphead bolts and so tapped the chuck body casting and fixed from the backplate side.

The runout is now significantly better than the original chuck. Plus it's good across the range from internal to external jaws. The only slight issue was the chuck key itself needed a little bit of finishing to get the square key to fit all of the locations on the chuck.

This Soba chuck from Chronos is rather nice and a real improvement overall on the original Warco chuck.

Very happy with the result, Nigel

16/04/2020 07:43:14
Posted by Ronald Morrison on 15/04/2020 21:17:21:

I just checked something on my lathe as I was getting a step when I tried to cut from both ends. I cut one end, turned the stock around and leaving just enough sticking out to run the dial indicator on found the runout and the location of that. I loosened the chuck and started slipping different feeler gauges in where the indicator showed the lowest, then tightening to check the runout. Eventually I got the runout to nearly zero. When I then turned the second end there was no step noticeable. I don't have a 4 jaw for that lathe so this is a poor man's way to compensate.

Hi Ronald, that works fine, but the compensation on my chuck is different at different diameters and although I can shim each time that is a pain I don't need. The Hobbymat is 2 thou out and so ok for a lot of items and I just mark the bar and chuck if I rotate. Cheers, Nigel

15/04/2020 16:15:04
Posted by Tony Pratt 1 on 15/04/2020 15:41:33:

Nigel,

Although not ideal is the run out a problem?

Tony

Hi Tony, It's just a pain if you want to turn the part around and machine both sides. OK, for really accurate work I use a 4-jaw independent chuck, eg for the wheel rims on my traction engine, but for normal use the runout is too significant to be able to re-chuck the part. Mainly though it's just irritating. Best regards, Nigel

15/04/2020 14:31:22

The runout on the 3-jaw chuck has finally got the better of me, I think the issue is due to me behaving like a gorrilla some time ago and over-strecthing the scroll. Anyway, I measured the runout at a number of diameters:

  • Dia=22.35mm Runout=0.140mm
  • Dia=41.3mm Runout=0.120mm
  • Dia=100mm Runout=0.234mm

This compares to my Hobbymat with a 3jaw that has a runout at Dia=22.35mm of 0.054mm

Obviously zero is the best runout and unlikely to get to that level on a 3 jaw chuck. I thought about buying the Pratt-Burnerd chcuk as a replacement, but the reviews on here and other places didn't look good. So I've ordered a much cheaper Soba 125mm 3-jaw.

Thread: 1/20th Scale Traction Engine
29/03/2020 10:06:19
Posted by bricky on 24/03/2020 00:03:22:

Nigel have you tried the Burrell museum in Thetford for information on your engine,if it is still there.

Frank

Hi Frank, thanks, I looked at the museum online, will drop them a line. Best regards, Nigel

29/03/2020 10:05:00

I now have an input power of 128.7 Watts and an engine output power of 3.3 Watts, the Steam Engine and Boiler Efficiency is a ratio of the output and input:

Steam Engine and Boiler Efficiency = Output Power / Input Power

Miniature Traction Engine Efficiency = 3.3 / 128.7 = 0.0256 = 2.56%

So, my calculated efficiency is 2.56% that feels very high for this small system and I expect a lot more losses when I put this into practice.

Thread: Morse tapers
27/03/2020 22:09:59

 

Just thought I would copy this table in from my page on this subject to complete the list:

Morse Taper No. Gauge Depth (inches) Gauge Diameter (inches) Hang (inches) Taper per inch 1/2 included angle °
0 2 0.252 1/8 0.05205 1° 29′ 30”
1 21/8 0.369 1/8 0.04988 1° 26′
2 29/16 0.572 3/16 0.04995 1° 26′
3 33/16 0.778 3/16 0.05020 1° 26′ 15”
4 41/16 1.02 1/4 0.05194 1° 29′
5 53/16 1.475 1/4 0.05263 1° 30′ 30”
6 71/4 2.116 5/16 0.05214 1° 30′
7 10 2.75 3/8 0.052 1° 30′

Edited By JasonB on 28/03/2020 06:50:56

Thread: 1/20th Scale Traction Engine
23/03/2020 22:17:41

I've been approximating the amount of fuel used and steam produced, my simple calculation for a boiler fired by methylated spirit and driving an engine at 12mm bore and stroke at 300rpm gives:

1.38g water per minute => 0.26g fuel / minute

the steps are given in more depth here, but wanted to share the high level numbers for this 1/20th scale traction engine.

09/03/2020 21:48:49

Had to share the pair of rear wheels with the bolts riveted over and the spokes soft soldered to the hubs. The alignment is superb as I used a jig to align the hubs and held in place whilst I heat jig and wheel to solder. All of the stages of building these wheels has taken me some time (around 8 weekends worth), but the final result is quite rewarding.

I need to machine the outer face of the spokes on the hub to get a clean, parallel finished surface onto which I can fit the hub cap. I'm a tad nervous of this machining step.....will let you know, Nigel

08/03/2020 16:11:43
Posted by Richard S2 on 08/03/2020 14:19:41:

Very nice to see more small scale work. Another one here in agreement of drawing by hand. Have to get the use out of my 40 year old drawing set made in czechoslovakia. Keep the updates coming.

Richard

Just been looking at the photographs of the Minnie TE that you've made, fantastic workmanship.

08/03/2020 13:08:21

Miniature Traction Engine Parts

I will have to arrange another photo of the set of parts I have with the general elevation drawing.

This does show the section through the boiler and firebox as I was talking about in the earlier post. Hope this all helps set the scene for this engine.

The plans are hand drawn using a Rotring drawing table, I've played with CAD, but at the end of the day this is a hobby that relaxes me and drawing using an old fashioned board works well. The drawings are progressing and I will make them available, just not sure quite how to do that as yet...might be as pdf's, might be free as long as people send me updates and make the updates free, I thought about charging for them, but think that would just be a token amount to cover some costs - if you have experience of selling plans or giving them away for free then do let me know

08/03/2020 11:26:54
Posted by Bill Chugg on 08/03/2020 11:15:13:

Nigel.

Menbership of the TRACTIONTALK forum may be worthwhile.

It is traction engines only, full size and minatures.

I am sure a question on there ref full size spec will provide you with the info.

Bill

Hi Bill, thanks for that, will have a look and post a thread. Best regards, Nigel

08/03/2020 11:08:09

I wasn't really making this to a scale, it was more to the drawing that I found online. I think this Burrell is just one of the best looking engines in terms of proportions.

Burrell Traction Engine Drawing

I scaled this to roughly fit a sheet of A4 paper and keeping the rear wheel rim and treads under 4 inches in diameter. The angle was me roughly looking at the angle of the boiler. I have since then worked out the scale from the specifications of some other models of this engine and it is somewhere around 1/20th in scale. I would love to find the specifications of this actual fullsize engine, from my searching I could not find the original drawings. But this is more about something that looks right and at this scale I will have to make a number of simplifications for me to be able to make it.

I have some concerns around the clearance of the crank above the top of the firebox on my current design, but this is not unsolvable. The boiler design is simple and the firebox is a steel construction that the boiler fits into. This means you get heat on the bottom rear of the boiler and through the tubes. Not perfect, but this is a tiny boiler and this makes it easier. I will continue to add items here as I go, if you want the real detail and access to drawings then please visit my blog. Thanks, Nigel

Edited By Nigel (egi) on 08/03/2020 11:25:21

07/03/2020 20:10:49

I've started to design and build a miniature traction engine. My first idea was to ensure the elevation fits onto a sheet of A4 paper. This next image shows a rear wheel that is 97mm in diameter:

The spokes are 0.9mm thick brass - a great trick is to add an MDF table to the bandsaw so that you can support the brass sheet whilst cutting it.

That's it for now, will add more details as I go, Nigel

Thread: Round indexable tips.
27/01/2019 11:39:45

I've been using a round tipped lathe tool from Glanze, quite useful for profile fillets:

**LINK**

The downside is they can chatter as the cutting width is quite long

Thread: 5 Cylinder Rotary Air Engine
27/01/2019 11:34:57

This was the limit of the plans that I constructed - really just to check the master and slave conrod clearances

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