Model Engine Maker

Engines => From Kits/Castings => Topic started by: Chipmaster on October 01, 2019, 02:15:40 PM

Title: Retlas "Manchester" Dynamo
Post by: Chipmaster on October 01, 2019, 02:15:40 PM
Quote from Doncaster Show post (reply 11)  by Alyn Foundry

“The AGB Dynamo....

Andy has a set of castings for the Retlas " Manchester " dynamo, Vincent and I developed this around the early Eighties. Once " fine tuned " we were able to light a 55W car headlamp bulb with no problem........

Cheers Graham”

So here are some pictures of the castings.

This is the base casting Graham gave me, he also gave me the keeper or top, I had them shot blasted and sprayed them with primer straight away. It might be another year before I can start work on this.

(https://live.staticflickr.com/65535/48826593757_e321aef688_z.jpg) (https://flic.kr/p/2hoD4ep)image (https://flic.kr/p/2hoD4ep) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

Graham also gave me the two brass oil reservoir covers and name plate. At the time he thought the armature would be very expensive.... The two bearing supports were cast by the AJD  Foundry  using patterns I borrowed from Graham.

(https://live.staticflickr.com/65535/48826439487_9fd9708b30_z.jpg) (https://flic.kr/p/2hoCgnz)Building Retlas 1034 (https://flic.kr/p/2hoCgnz) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

With the Retlas engine in the background.

(https://live.staticflickr.com/65535/48825909768_c92623983d_z.jpg) (https://flic.kr/p/2hozxUu)Building Retlas 1035 (https://flic.kr/p/2hozxUu) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

(https://live.staticflickr.com/65535/48825909633_1c00a8928e_z.jpg) (https://flic.kr/p/2hozxSa)Building Retlas 1037 (https://flic.kr/p/2hozxSa) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

(https://live.staticflickr.com/65535/48826285176_258089a593_z.jpg) (https://flic.kr/p/2hoBtv3)Building Retlas 1038 (https://flic.kr/p/2hoBtv3) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

(https://live.staticflickr.com/65535/48826285321_5014008f05_z.jpg) (https://flic.kr/p/2hoBtxx)Building Retlas 1039 (https://flic.kr/p/2hoBtxx) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

(https://live.staticflickr.com/65535/48826439262_f8578e8de0_z.jpg) (https://flic.kr/p/2hoCgiG)Building Retlas 1040 (https://flic.kr/p/2hoCgiG) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

Pattern Lucas C40 armature obtained for £27.00 inclusive from a supplier in Warwickshire, England  :whoohoo:

(https://live.staticflickr.com/65535/48826439202_d6391322aa_z.jpg) (https://flic.kr/p/2hoCghE)Building Retlas 1041 (https://flic.kr/p/2hoCghE) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

(https://live.staticflickr.com/65535/48826285186_dce599d091_z.jpg) (https://flic.kr/p/2hoBtvd)Building Retlas 1042 (https://flic.kr/p/2hoBtvd) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

Picture of the plan, the 'Keystone effect' is because the plan was large and I was using a hand held camera in Graham's kitchen

(https://live.staticflickr.com/65535/48826487812_ee3de0f7c5_z.jpg) (https://flic.kr/p/2hoCvJL)Retlas Dynamo 1 (2) (https://flic.kr/p/2hoCvJL) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

Andy
Title: Re: Retlas "Manchester" Dynamo
Post by: Alyn Foundry on October 01, 2019, 04:32:52 PM
Hi Andy.

It's nice to see all the parts together in one place!

I was quite shocked by how cheap the armature was but they are probably being mass produced in the far East. There were literally millions in use on cars here in the UK before the alternator became popular. If you're a purist car restorer then the Lucas Dynamo is a must.

As you can see from one of your photos the armature will need some modifications, Vincent " upped " the shaft diameter to 3/4" and lengthened them too.

The final  touch was to " serve " the windings with a thin woven string using super glue dabbed here and there then he used Brown shoe polish to get the desired colour. A final coat of Shellac was given to improve the look and insulation.

I'll be following your progress when you start Andy. Please don't hesitate to ask for advice.

Cheers Graham.
Title: Re: Retlas "Manchester" Dynamo
Post by: Jasonb on October 01, 2019, 04:41:51 PM
Looks interesting Andy

Can I ask what the OD of the armature is, I got one that is a little on the small sid efor the main motor I was going to build at 27.5mm, cheap at under £10 and hiding inside a RS 755 motor. Would really like something about 38-40mm.

Nice to know another expert advocates the use of string ;)
Title: Re: Retlas "Manchester" Dynamo
Post by: Chipmaster on October 01, 2019, 06:59:33 PM
Hi Jason,
The diameter of the armature is  2.376” / 60.34mm.

https://www.autoelectricalspares.co.uk/c40-dynamo-armature-12v-22a-replaces-lucas-227271-3770-p.asp

Andy
Title: Re: Retlas "Manchester" Dynamo
Post by: Chipmaster on October 01, 2019, 07:02:32 PM
Hi Graham,
I’m sure I’ll take up your offer of advice when the time comes.
Cheers
Andy
Title: Re: Retlas "Manchester" Dynamo
Post by: Alyn Foundry on October 01, 2019, 07:29:59 PM
A little history.

A few will know that my background was in electrical engineering and with a passion for vintage machinery.

I had the privilege of both seeing and working on a wide range of " machines " that spanned nearly a century. North Wales has many hydroelectric stations one in particular dated at 1905 was the oldest that I had seen. The turbines and alternators now replaced by a single and highly efficient replacement.

After Vincent had completed his Retlas he found that a load " softened " the rather erratic running nature so we discussed various means towards this end. A dynamo was the obvious choice as you can easily place a given electrical load in the form of lightbulbs.

Vincent's choice was a " Manchester " style as they were of very simple construction. The base becomes one pole, either North or South and the two field coils are wired to provide the electromagnetic influence to the top and bottom. The choice of a Lucas dynamo armature was twofold, they were very common and cheap because nobody wanted them and a low output voltage was safe in the usually wet rally field environment.

The prototype was a very plain affair, a simple cross at the bottom and the top is the only bit that wasn't remodelled. All the other patterns were redone after the Dynamo was proved to work. I've forgotten who wound the coils but I think we scavenged the Copper wire from the donor machine. This ensured that we had the correct resistance.

You will notice that the " brushgear " can be rotated about the axis of the commutator. This was a method used on early DC machines to combat something called " armature reaction " . This effect happens as more load is placed upon the generator, bending the magnetic flux which, in turn moves the best output from the commutator. As a result arcing occurs which, if left unchecked quickly burns the segments. The operator would then rotate the brushgear to find the point of least arcing.

The Retlas Dynamo was also fitted with Brass gauze brushes and ring oilers for that extra look of authenticity. The overall finish was such that Vincent's Dynamo fooled many an expert eye over the years few believing that it was home made.

Cheers Graham.
Title: Re: Retlas "Manchester" Dynamo
Post by: Chipmaster on October 01, 2019, 10:06:41 PM
Here are pictures of two Retlas dynamos that I copied from the Internet some time ago, I don't have any details about them.
Andy

(https://live.staticflickr.com/65535/48828864671_c55589706e_o.png) (https://flic.kr/p/2hoQGi6)rd2[1] (https://flic.kr/p/2hoQGi6) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

(https://live.staticflickr.com/65535/48828864616_56c44a542b_o.png) (https://flic.kr/p/2hoQGh9)rdj2[1] (https://flic.kr/p/2hoQGh9) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr
Title: Re: Retlas "Manchester" Dynamo
Post by: steam guy willy on October 01, 2019, 11:55:45 PM
Hi , Interesting project..I was also an electrical engineer in the Army and they had quite a few old 'Machines" that the y use to start up.  including one with the handle for adjusting the brush position !!  Also there is a black wire connected to the frame  ? is this part of the electrical circuit ?? and are the  4 middle connections able to reverse the polarity of the output  ?...and on the green one the rotor wire seem to be coloured slightly red and black...havent seen that before ??


willy
Title: Re: Retlas "Manchester" Dynamo
Post by: Alyn Foundry on October 02, 2019, 10:08:14 AM
Good morning Willy.

Like Andy I've seen these pictures before but the builders and their methods are unknown.

With the Black one I surmise that they have only isolated one of the brushes and the frame becomes a return to the terminal block.

I'd never noticed the different colours in the enamel insulation before, well spotted. The armature is however " proprietary " so this is something that the manufacturer might have used to designate the coil termination to the commutator?

Cheers Graham.

Title: Re: Retlas "Manchester" Dynamo
Post by: Admiral_dk on October 02, 2019, 11:45:58 AM
To me it looks like it is a "Bifilar Winding" - means that there are two (or more) parrallel wires, wound together as if there where one. There can be several reasons for this - in this case, to easier to get the coils into place after they are wound.
Title: Re: Retlas "Manchester" Dynamo
Post by: Chipmaster on October 28, 2020, 10:11:01 PM
After a twelve month gap in this thread I have started to build the dynamo. Here are extracts from Grahams drawings that I photographed back in 2017.

(https://live.staticflickr.com/65535/50542028521_6e0a47f4ab_z.jpg) (https://flic.kr/p/2k1e7dR)Dynamo Base (https://flic.kr/p/2k1e7dR) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

(https://live.staticflickr.com/65535/50541304528_67479c4e37_z.jpg) (https://flic.kr/p/2k1ap1d)Dynamo side view (https://flic.kr/p/2k1ap1d) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

(https://live.staticflickr.com/65535/50541305718_8920eb9332_z.jpg) (https://flic.kr/p/2k1apmJ)Dynamo end view (2) (https://flic.kr/p/2k1apmJ) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

(https://live.staticflickr.com/65535/50541304533_c815f5fb97_z.jpg) (https://flic.kr/p/2k1ap1i)Dynamo bearings (https://flic.kr/p/2k1ap1i) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

There are a some differences between my castings and the drawings.
1. My two pedestal castings have lugs on each side for bolts or studs whereas the drawings show two bolts 1.1/2" apart coming up form the underside of the base.
2. The base casting isn't quite as long as the drawing.
3. The height of the pedestal castings and the pads they sit on had to be reduced to ensure the keeper or yoke would be a reasonable thickness after machining it to clear the armature and eventually look right.

In this picture I had machined the mild steel field coil cores to a height of exactly three inches then determined the height of the armature shaft.
 
(https://live.staticflickr.com/65535/50542169277_41457f595f_z.jpg) (https://flic.kr/p/2k1eQ4F)IMG_2116 (https://flic.kr/p/2k1eQ4F) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

(https://live.staticflickr.com/65535/50542170327_c6b11341db_z.jpg) (https://flic.kr/p/2k1eQnM)IMG_2103 (https://flic.kr/p/2k1eQnM) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

Milling the underside of a pedestal flat.

(https://live.staticflickr.com/65535/50542170382_bd946e1189_z.jpg) (https://flic.kr/p/2k1eQoJ)IMG_2100 (https://flic.kr/p/2k1eQoJ) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

I spotted through the base into the keeper casting.

 (https://live.staticflickr.com/65535/50541305588_c04c37c4c6_z.jpg) (https://flic.kr/p/2k1apju)IMG_2118 (https://flic.kr/p/2k1apju) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

Tapped the base and the field coil cores 1/2" Whitworth and used short studs in the base and short bolts through 1/2"
holes in the keeper to hold it together.

(https://live.staticflickr.com/65535/50542170287_aa5fba9e0d_z.jpg) (https://flic.kr/p/2k1eQn6)IMG_2119 (https://flic.kr/p/2k1eQn6) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

(https://live.staticflickr.com/65535/50541305513_f7a910d9fe_z.jpg) (https://flic.kr/p/2k1apic)IMG_2121 (https://flic.kr/p/2k1apic) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

Andy
Title: Re: Retlas "Manchester" Dynamo
Post by: Alyn Foundry on October 29, 2020, 12:29:08 PM
Hi Andy.

As always, excellent workmanship....  :ThumbsUp:

The Retlas Dynamo evolved, please see my earlier post. It moved from a practical working machine to something, I hope could be considered, nice looking?

As members of the FB group will know we've been discussing the field coils. The Lucas unit has field coils that had, in general around 6 Ohms resistance per coil.

I've been doing a little mathematics and a 1Kg  spool of 22SWG which is approximately 0.75 mm ECW has a resistance of 0.04 Ohms per Metre. This equates to 10.1 Ohms. I'm of the opinion that each bobbin will require 500 grams of wire for a close match to the original machine.

Looking forward to the next instalment Andy.

Cheers Graham.
Title: Re: Retlas "Manchester" Dynamo
Post by: Dave Otto on October 29, 2020, 04:11:43 PM
Interesting project Andy,
I'm looking forward to following along.

Dave
Title: Re: Retlas "Manchester" Dynamo
Post by: Chipmaster on October 29, 2020, 05:34:59 PM
Thank you very much Graham and Dave.

I hope I haven't painted myself into a corner with my sequence of operations, my concern was how to machine the pole pieces and have a minimal air gap between them and the armature. The only way I can machine the pole pieces is to use a between centres boring bar with the dynamo mounted on the lathe cross slide. However, I will need to be able to check the gap with the assembled armature and the dynamo remaining on the cross slide. The outcome will be dependent on how well the armature shafts fit and run in their plain bronze bearings.

I decided to mill the surfaces of the two pedestals so that I could bolt them in turn, directly to an angle plate and faceplate to ensure the centre heights matched. There were differences between the pair of pedestal castings which meant I had to compromise on the thickness of the bearing housings but perhaps JB Weld or Milliput can be used if necessary.

(https://live.staticflickr.com/65535/50542029226_c9aec40688_z.jpg) (https://flic.kr/p/2k1e7r1)IMG_2127 (2) (https://flic.kr/p/2k1e7r1) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

Boring out the pedestals to 1".

 (https://live.staticflickr.com/65535/50542029191_4c678fa06f_z.jpg) (https://flic.kr/p/2k1e7qp)IMG_2140 (https://flic.kr/p/2k1e7qp) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

 (https://live.staticflickr.com/65535/50541305363_bdc020eb7b_z.jpg) (https://flic.kr/p/2k1apfB)IMG_2144 (https://flic.kr/p/2k1apfB) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

Being able to rotate a length of 1" diameter ground bar mounted in the pedestals without binding confirmed that the centre heights matched.

(https://live.staticflickr.com/65535/50542029121_8748f16109_z.jpg) (https://flic.kr/p/2k1e7pc)IMG_2151 (https://flic.kr/p/2k1e7pc) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

In this picture you can see what I meant about compromising on the thickness of the bearing housings.

(https://live.staticflickr.com/65535/50542029081_ff2dfe9b47_z.jpg) (https://flic.kr/p/2k1e7ov)IMG_2154 (https://flic.kr/p/2k1e7ov) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

To reduce the height of the armature I milled away the pads that the pedestals sit on, that gave me about 0.09".

(https://live.staticflickr.com/65535/50541305253_f9dd5f288f_z.jpg) (https://flic.kr/p/2k1apdH)IMG_2156 (https://flic.kr/p/2k1apdH) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

(https://live.staticflickr.com/65535/50542169967_acddce7a71_z.jpg) (https://flic.kr/p/2k1eQgz)IMG_2158 (https://flic.kr/p/2k1eQgz) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

The faces and underside of the base and keeper castings were flat and in the same planes / in line before I started machining them so I assume they had been machined years ago before they acquired the 'special coating'.

(https://live.staticflickr.com/65535/50542170432_abcb14cff1.jpg) (https://flic.kr/p/2k1eQpA)image (https://flic.kr/p/2k1eQpA) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

Unfortunately the 1" precision ground steel bar isn't long enough to be used to position the dynamo between centres on my lathe so another one has been ordered. However, it was sufficient for keeping the pedestals lined up as they were bolted down to the base.

(https://live.staticflickr.com/65535/50542028601_3ba05c9359.jpg) (https://flic.kr/p/2k1e7fe)IMG_2191 (https://flic.kr/p/2k1e7fe) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

Andy

 
Title: Re: Retlas "Manchester" Dynamo
Post by: Roger B on October 29, 2020, 08:16:11 PM
Looking good  :ThumbsUp:  :ThumbsUp:  :wine1:

I am following along  :)
Title: Re: Retlas "Manchester" Dynamo
Post by: Chipmaster on October 30, 2020, 10:10:32 PM
The pattern Lucas C40 armature shafts are 15mm diameter and far too short for this dynamo.

(https://live.staticflickr.com/65535/50542169937_a827856081.jpg) (https://flic.kr/p/2k1eQg4)IMG_2161 (2) (https://flic.kr/p/2k1eQg4) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

So 3/4" diameter precision ground mild steel bar was bored out to fit over the 15mm shafts .

(https://live.staticflickr.com/65535/50542169877_63bbca3fc5_z.jpg) (https://flic.kr/p/2k1eQf2)IMG_2168 (2) (https://flic.kr/p/2k1eQf2) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

The results of boring out of the 3/4" bar were surprising, far better than expected, the fit is so good that the air trapped inside acts like a spring, but its not tight. Perhaps I'll have to file a small flat on the shafts otherwise most of the Loctite 638 will be blown out when I push the shafts home.

I hope to use the 3/4" shafts as the are, just shortened a bit.

(https://live.staticflickr.com/65535/50541304918_75f297ff1a_z.jpg) (https://flic.kr/p/2k1ap7W)IMG_2173 (2) (https://flic.kr/p/2k1ap7W) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

Andy

Title: Re: Retlas "Manchester" Dynamo
Post by: Admiral_dk on October 31, 2020, 07:20:02 PM
Quote
Perhaps I'll have to file a small flat on the shafts otherwise most of the Loctite 638 will be blown out when I push the shafts home.

Thinking out loud - how about drilling a very small hole in from the side or the other end to let the air out and keep the perfect alignment ...?
Title: Re: Retlas "Manchester" Dynamo
Post by: Chipmaster on October 31, 2020, 07:59:49 PM
Yes Per that's probably the best solution. I cleaned the parts with acetone in case there was an oil film but still had the same result, reckon my Colchester Chipmaster lathe surpassed itself on this occasion.

This afternoon I machined the two bronze bushes that fit in the bearing pedestals. They're 1" od 3/4" id and 2.1/2" long.

(https://live.staticflickr.com/65535/50551240338_1c70fdf7f1_z.jpg) (https://flic.kr/p/2k23jzh)IMG_2206 (https://flic.kr/p/2k23jzh) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

(https://live.staticflickr.com/65535/50552104907_acb0dba28e_z.jpg) (https://flic.kr/p/2k27KzD)IMG_2208 (2) (https://flic.kr/p/2k27KzD) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

(https://live.staticflickr.com/65535/50551976206_dc8a9594c2_z.jpg) (https://flic.kr/p/2k276jE)IMG_2210 (2) (https://flic.kr/p/2k276jE) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

(https://live.staticflickr.com/65535/50551976146_d02a494fec_z.jpg) (https://flic.kr/p/2k276iC)IMG_2213 (2) (https://flic.kr/p/2k276iC) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

(https://live.staticflickr.com/65535/50552104717_d9c2e4e981_z.jpg) (https://flic.kr/p/2k27Kwn)IMG_2214 (https://flic.kr/p/2k27Kwn) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

So far so good, the bushes line up and the length of 3/4" ground steel bar rotates freely, I hope the armature will line up and revolve freely with it's extended shafts.

Andy
Title: Re: Retlas "Manchester" Dynamo
Post by: crueby on October 31, 2020, 11:04:48 PM
Fascinating project, following along....   :popcorn: :popcorn: :popcorn:
Title: Re: Retlas "Manchester" Dynamo
Post by: Chipmaster on November 04, 2020, 09:04:52 PM
Cheers Crueby and Roger  :cheers:

I have shortened the extension shafts for the armature to the required lengths and centre drilled the ends.  With the shorter extension I carried on with a thin long series drill right through the centre to allow air to escape and prevent the hydraulic problem I was having.

Here is the armature with it's extension shafts and bronze bearings.

  (https://live.staticflickr.com/65535/50566615348_6c0f5f05e0_z.jpg) (https://flic.kr/p/2k3p82E)IMG_2228 (https://flic.kr/p/2k3p82E) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

Over to the lathe, I could now remove the topslide and prepare the cross slide for line boring the dynamo.

Two 30 x 20 x 300mm bright drawn mild steel bars were fastened using two of the 5/16" UNC rear tool post mount threaded holes and the two holes vacated by the top slide mount. the centre drilled 1" precision ground mild steel (PGMS) bar lined up the whole job when supported between centres.

 (https://live.staticflickr.com/65535/50567502917_f6484acc26_z.jpg) (https://flic.kr/p/2k3tESz)IMG_2232 (https://flic.kr/p/2k3tESz) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

There are two holes in the base which I will use to hold it down, one is arrowed in this picture.

(https://live.staticflickr.com/65535/50566615273_113f3785fd_z.jpg) (https://flic.kr/p/2k3p81n)IMG_2233 (https://flic.kr/p/2k3p81n) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

Ready

(https://live.staticflickr.com/65535/50567366801_8a40fdf9c7_z.jpg) (https://flic.kr/p/2k3sYpK)IMG_2234 (https://flic.kr/p/2k3sYpK) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

Packing was used to raise the dynamo to the required centre height and the cross slide gibs tightened up to keep it in line.

(https://live.staticflickr.com/65535/50566615603_cca93482d2_z.jpg) (https://flic.kr/p/2k3p874)IMG_2236 (https://flic.kr/p/2k3p874) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

The two bearing pedestals have been removed and I'll convert the one inch PGMS bar into a between centres boring bar tomorrow when I've found a suitable piece of round high speed steel for the tool bit.

(https://live.staticflickr.com/65535/50566615608_97fd8a5c14_z.jpg) (https://flic.kr/p/2k3p879)IMG_2237 (https://flic.kr/p/2k3p879) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

Two reels of 0.75mm copper wire for the two field coils were delivered today. These 500g reels equate to approximately 142 metres or 465 feet per reel. That should be enough for at least 300 turns per field coil.
However, I also need to find something that can be adapted for the bobbins on which to wind the coils that will slip over the field coil steel cores.

(https://live.staticflickr.com/65535/50567366361_5651077051_z.jpg) (https://flic.kr/p/2k3sYha)IMG_2239 (https://flic.kr/p/2k3sYha) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

Andy


Title: Re: Retlas "Manchester" Dynamo
Post by: Alyn Foundry on November 05, 2020, 11:40:00 AM
Hi Andy.

You're set up for what is most likely the trickiest part of the whole job, looking good.

Don't forget that the clearance between the " Pole pieces " to the Armature is but a few Thousandths of an Inch. If you underbore the diameter you can always use some shim Steel and if you overbore well you can take a little off each core.

For the bobbins there are a number of ways. PVC household water waste pipe with discs of plastic glued at either end is one method. Alternatively there are many plastics available in billet form so you could carve out a couple from the solid.

For me it was the " aesthetics " that mattered most. Once the coils were wound we used PVC electrical tape to hold them in place but then rolled on several layers of heavy duty Brown parcel paper to build up the bobbins. We then used White butchers string to " serve " the finishing layer. Boot polish was used to get the colour right and then a couple of coats of Shellac to finish.

The finishing touch was to sleeve the Copper wire with a cloth looking sheath.

Cheers Graham.
Title: Re: Retlas "Manchester" Dynamo
Post by: Chipmaster on November 05, 2020, 09:17:00 PM
Yes Graham, quite tricky, here's some line boring video.

https://www.youtube.com/watch?v=gqwiIp2joHs

When I stopped work for dinner this evening the distance between the poles was two inches. In the picture below you can see how the machining hasn't yet reached the full width of the lower pole piece end nearest the camera but it should be ok when the diameter of the armature 2.376" is reached if my estimate is correct, the machined surface of the upper pole piece is fine.

(https://live.staticflickr.com/65535/50570855106_65bc366a11_z.jpg) (https://flic.kr/p/2k3LRmW)IMG_2249 (https://flic.kr/p/2k3LRmW) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

Andy
Title: Re: Retlas "Manchester" Dynamo
Post by: Dave Otto on November 05, 2020, 11:21:52 PM
Looking good Andy!
Graham, that is a great idea using the butcher paper to even out the coils and make a nice foundation for the cord covering. I have always admired the how nicely the coils were finished on the old dynamos.

Dave
Title: Re: Retlas "Manchester" Dynamo
Post by: Alyn Foundry on November 06, 2020, 02:11:08 PM
Thanks for the " boring " video Andy....  :)

A video like that is worth several thousand words of text !

I have only ever done " between centres " boring a couple of times myself, doing the main bearings for Vincent's Retlas engine. My Le Blonde RP has a very long front to the saddle, I simply drilled and tapped 4 holes to suit the base casting and bored away.

Going back to the bobbins I should have mentioned that they could also be printed too.

Your final job after the correct diameter is reached will be to take back/flat off the roughness of the pole pieces. This will ensure the magnetic field is transferred into the armature proper.

Cheers Graham.
Title: Re: Retlas "Manchester" Dynamo
Post by: Alyn Foundry on November 06, 2020, 02:53:10 PM
As Andy plugs away at the pole pieces I'll provide some information for the next stage of operations.

All DC generators will act like a motor if a DC voltage is applied to them. This knowledge will be useful in setting up the machine.

I wanted Vincent to go the whole way with his by fitting wire gauze brushgear. But Vincent didn't want to be messing and carved up the donor Lucas Dynamo for its Carbon brushes and springs. The very early machines all used gauze and used the natural spring in the material to keep them in contact with the commutator. This meant that the gauze had to be placed at a near right angle to the commutator instead of the direct on position of Carbon brushes. The drawing shows a rectangular housing with knurled " pinch screws " that hold the gauze layers in place and another screw to lock the housing to the support pillar.

The design suggests a Negative earth situation so that only one, the Positive brush, needs isolation from the frame.

This machine will be used in a " shunt wound " configuration which means that the Armature will be in parallel to the field coils. We shall have to wait and see if we need to use a shunt field resistance when the time comes.

Cheers Graham.
Title: Re: Retlas "Manchester" Dynamo
Post by: Chipmaster on November 06, 2020, 09:38:19 PM
I continued hacking away at the dynamo pole pieces this afternoon but the job was delayed by having to dig up dahlia tubers because of frost so I still haven't finished. A diameter of 2.3185" was reached by 5.15. About 65 thou left to reach the required diameter. The boring gar is removed periodically to measure the job with a telescopic gauge.

Using speeds of between 50 to 100 rpm with a high feed rate and ten to fifteen thou cuts, the finish is pretty good. With this set up I can leave the dynamo mounted on the cross slide, remove the boring bar and check clearance for the armature by mounting it between the lathe centres. I can also assemble the dynamo with the pedestal bearings to check the armature to pole piece air gap

So far I have guessed the cut  but if I want to increase the cut precisely I loosen the retaining grub screw and advance the tool bit by lightly tapping it from behind. The movement is measured by a dial test indicator.

 (https://live.staticflickr.com/65535/50573194673_c2cf64130e_z.jpg) (https://flic.kr/p/2k3YQQi)IMG_2253 (2) (https://flic.kr/p/2k3YQQi) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr


Nearly done.

(https://live.staticflickr.com/65535/50573941401_5507185114_z.jpg) (https://flic.kr/p/2k43ENV)IMG_2256 (https://flic.kr/p/2k43ENV) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

(https://live.staticflickr.com/65535/50573194518_f416f4f2a9_z.jpg) (https://flic.kr/p/2k3YQMC)IMG_2260 (https://flic.kr/p/2k3YQMC) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

Hi Graham,  "Your final job after the correct diameter is reached will be to take back/flat off the roughness of the pole pieces. This will ensure the magnetic field is transferred into the armature proper."

Does that apply to just the horizontal surfaces such as arrowed in this picture or all over?

(https://live.staticflickr.com/65535/50574073582_277fd6505c_z.jpg) (https://flic.kr/p/2k44m6U)IMG_2259 (https://flic.kr/p/2k44m6U) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

Andy
 

 
Title: Re: Retlas "Manchester" Dynamo
Post by: Alyn Foundry on November 07, 2020, 10:55:23 AM
Good morning Andy.

Yes, those are the areas to pay attention to. Just remove as much metal so as to clean up the faces.

As the armature will be in really close proximity to the magnetic flux generated by the field coils you don't need to worry about " air gap " at the sides.

Cheers Graham.
Title: Re: Retlas "Manchester" Dynamo
Post by: Jasonb on November 07, 2020, 01:15:39 PM
Graham, is the direction that the wire is wound in critical on a dynamo, I know it can affect the bi-polar motors?

I cut my bobbins for "lecky" from Delrin but they were quite a bit smaller so Grahams suggestion of tube with glued on ends sounds best.
Title: Re: Retlas "Manchester" Dynamo
Post by: Alyn Foundry on November 07, 2020, 03:01:41 PM
Hi Jason.

Not super critical because the magnetic polarity can be reversed electrically but it would be best if both coils were wound in the same direction.

What is different about the Manchester style is that the frame becomes one pole, either North or South and the top cover becomes the opposite magnetic pole. With this in mind if both poles are wound in the same direction they will both exhibit the same magnetic polarity with the same DC ( Direct Current ) voltage applied to the wires.

Cheers Graham.
Title: Re: Retlas "Manchester" Dynamo
Post by: Chipmaster on November 07, 2020, 07:10:51 PM
This afternoon I finished machining the poles to clear the armature. In this first picture the armature is mounted between the lathe centres with one of the shaft extensions.

(https://live.staticflickr.com/65535/50576120858_e2cb3bdab8_z.jpg) (https://flic.kr/p/2k4eQFL)IMG_2261 (https://flic.kr/p/2k4eQFL) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

The clearance was close, I could hear slight rubbing as I turned it by hand and the thickness of a cigarette paper was enough to jam it.

(https://live.staticflickr.com/65535/50576987252_4899d28932_z.jpg) (https://flic.kr/p/2k4jheA)IMG_2267 (https://flic.kr/p/2k4jheA) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

I advanced the boring tool by 0.0015" to add 0.003" to the diameter then tested the air gap with the armature mounted with the extended shafts running in the pedestal bearings.

(https://live.staticflickr.com/65535/50576125108_6318e7e139_z.jpg) (https://flic.kr/p/2k4eRX3)IMG_2276 (https://flic.kr/p/2k4eRX3) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

The result seems pretty good, you can hear the rubbing sound in the first part of this video.

https://www.youtube.com/watch?v=ltWfr5HliUE

My next jobs will be milling oil chambers in each of the two pedestals and a surface for the armature reaction compensator to rotate on the pedestal adjacent to the commutator. At this stage the bronze bearings are a push fit in the pedestals, I will use a Loctite retainer to keep them in place after the oil chambers are completed. The little holes for returning excess oil to the chamber look challenging, there may not be enough pedestal casting to do that.

(https://live.staticflickr.com/65535/50577068837_657af3d928_z.jpg) (https://flic.kr/p/2k4jGue)Oil chamber (https://flic.kr/p/2k4jGue) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

Andy
Title: Re: Retlas "Manchester" Dynamo
Post by: samc88 on November 08, 2020, 09:41:46 PM
Nice work, I didn't realise how big this was until I saw the body mounted on your lathe
Title: Re: Retlas "Manchester" Dynamo
Post by: Chipmaster on November 09, 2020, 08:30:08 AM
Yes Sam it’s quite heavy, I hope my Retlas engine will be capable of driving it.

Andy
Title: Re: Retlas "Manchester" Dynamo
Post by: Roger B on November 09, 2020, 11:08:11 AM
That's looking good :praise2: As Sam says it's quite a beast  ::)
Title: Re: Retlas "Manchester" Dynamo
Post by: Chipmaster on November 09, 2020, 06:42:59 PM
Thanks for the compliment Roger, fortunately for me the dynamo is pretty straightforward compared with the exacting standards with your injectors and carburettors which I follow.
Andy
Title: Re: Retlas "Manchester" Dynamo
Post by: Chipmaster on November 09, 2020, 09:56:13 PM
Almost finished milling the oil chamber in one of the pedestals this afternoon. I used a 1/2" slot drill taking 0.015" to 0.020" deep cuts forming the slot which is 1.375" wide reaching a depth of 1.75" after about two hours, a slow process but I prefer to take it easy.
I will have to settle for a chamber slightly smaller than the drawing, there isn't enough pedestal casting for the chamber to have a length of 1.5". Tomorrow I'll deepen the chamber to 2" which is as deep as my slot drill can reach.

(https://live.staticflickr.com/65535/50584829471_db09ed749c_z.jpg) (https://flic.kr/p/2k51tsg)IMG_2292 (2) (https://flic.kr/p/2k51tsg) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

(https://live.staticflickr.com/65535/50584089913_ebabd2049c_z.jpg) (https://flic.kr/p/2k4WFBg)IMG_2293 (2) (https://flic.kr/p/2k4WFBg) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

(https://live.staticflickr.com/65535/50584829456_e800f37f0f_z.jpg) (https://flic.kr/p/2k51ts1)IMG_2302 (https://flic.kr/p/2k51ts1) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

Andy
Title: Re: Retlas "Manchester" Dynamo
Post by: Roger B on November 10, 2020, 07:41:12 PM
Thank you Andy  :) Although I know there are people following along with these things I am doing I sometimes feel like the strange kid playing on his own in the corner (mind you that sums up my school life  ::) )
Title: Re: Retlas "Manchester" Dynamo
Post by: Chipmaster on November 11, 2020, 09:34:42 PM
Having finished the long job of milling the oil chambers in each of the two pedestals I decided to use ring oilers as shown in the drawings. Originally I was going to use the 2.5" long plain bronze bearings with an oil hole in the centre for lubrication.

Here's a view down into the oil chamber,

(https://live.staticflickr.com/65535/50591432671_be4a4f07d7_z.jpg) (https://flic.kr/p/2k5Ajmx)IMG_2315 (2) (https://flic.kr/p/2k5Ajmx) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

The drawing,
(https://live.staticflickr.com/65535/50591604737_37fdd19832_c.jpg) (https://flic.kr/p/2k5Bcvc)Bearing and oiler (https://flic.kr/p/2k5Bcvc) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

I'll need to machine a small internal groove in each of the four ends of the pedestals and drill small holes for escaping oil to flow back into the chamber. The length of my bronze bearings will have to be reduced and a suitable slot milled across the centre for the oil rings.

(https://live.staticflickr.com/65535/50591432591_cb0c4c43ee_z.jpg) (https://flic.kr/p/2k5Ajka)IMG_2328 (2) (https://flic.kr/p/2k5Ajka) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

I wanted to make sure  that the oil chambers were large enough. Looks promising, I intend to run the 3/16" wide rings in a 5/16 or 3/8" slot.

 (https://live.staticflickr.com/65535/50591432631_cdf36c83e2_z.jpg) (https://flic.kr/p/2k5AjkR)IMG_2326 (2) (https://flic.kr/p/2k5AjkR) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

Andy
Title: Re: Retlas "Manchester" Dynamo
Post by: Jasonb on November 12, 2020, 07:10:55 AM
Is the idea that the shaft will cause the ring to slowly rotate thus bringing up a fresh supply of oil from the bottom of the pocket?

Unlikely to be a factor on a model but on something that may have run for many hours was there a risk of wearing a groove into the shaft?
Title: Re: Retlas "Manchester" Dynamo
Post by: Chipmaster on November 12, 2020, 08:20:51 AM
Hi Jason, yes the ring’s lower end dips in oil, as it rotates the oil is carried and deposited on the top of the shaft then travels out into the bearing. The rings are light so I agree, they’re unlikely to wear a groove into the shaft. Ring oilers are said to be common in slower stationary engines. I used to own a Lister A type stationary engine that used ring oilers on the main bearings.

Andy
Title: Re: Retlas "Manchester" Dynamo
Post by: Alyn Foundry on November 12, 2020, 11:39:25 AM
Wonderful !

I think this might be a " first " Andy.

In my youth I came across many machines lubricated in this manner. The Water company had many pumps still running from the early part of the 20th century. Some had ornate Glass and Brass covers so you could see them working.

I'm beginning to wonder if I haven't given enough " meat " on the casting to provide room for the oil return passage? The answer will soon be apparent, methinks....

Cheers Graham.
Title: Re: Retlas "Manchester" Dynamo
Post by: Chipmaster on November 12, 2020, 12:50:01 PM
Hi Graham. if drilling the oil return hole looks as though it would break out of the casting an alternative could be to form a small channel - like a gutter, in the bore of the iron casting directly beneath the bronze bearing. That should return oil to the chamber assuming the dynamo is level. I would use a tiny grinding point in a Dremel to do it, what do you think.

There might be other possibilities perhaps involving external pipe work but that may be difficult to seal.

A web in the casting below the bearings would make drilling the oil return hole safer.

Andy
Title: Re: Retlas "Manchester" Dynamo
Post by: Alyn Foundry on November 12, 2020, 02:14:08 PM
Hi Andy.

Agreed, you could also mill a corresponding channel on the underside of each Bronze tube too.

The " flow " will be viscosity related, if too small a hole is provided then the oil will capillary rather than run.

Thirty four years on and we're still in the development stage lol.... :)

Cheers Graham.
Title: Re: Retlas "Manchester" Dynamo
Post by: Chipmaster on November 12, 2020, 08:47:10 PM
This afternoon I machined the grooves to catch surplus oil and drain it back via 1/16" holes into the oil chambers inside the pedestal castings. It is almost two weeks since the pedestals were bored out to 1". I left the angle plate undisturbed on the faceplate in case I decided to attempt the ring oilers in the drawings.

It didn't take long to machine the four grooves, I decided to make them 0.080" square.

 (https://live.staticflickr.com/65535/50594742891_c0d74004ab_z.jpg) (https://flic.kr/p/2k5Thni)IMG_2330 (2) (https://flic.kr/p/2k5Thni) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

(https://live.staticflickr.com/65535/50594742856_62a6e61585_z.jpg) (https://flic.kr/p/2k5ThmG)IMG_2331 (https://flic.kr/p/2k5ThmG) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

It was necessary to form a notch using a Dremel with a grinding point so that I could get the best angle for the 1/16" drill. The angle was by judgement depending on how thick the casting appeared to be, I think I was lucky, the set up was extremely dodgy! Reckon the 1/16" holes are very close to the surface of the castings so no fettling in this area, will probably add a layer of Milliput or JB Weld to achieve a smooth surface.

 (https://live.staticflickr.com/65535/50594005433_c4f18b4a99_z.jpg) (https://flic.kr/p/2k5Pv9v)IMG_2335 (https://flic.kr/p/2k5Pv9v) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

Green wire to show where the oil drainage holes emerge in the oil chamber.

(https://live.staticflickr.com/65535/50594742831_f0155f3ddf_z.jpg) (https://flic.kr/p/2k5Thmg)IMG_2332 (https://flic.kr/p/2k5Thmg) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

Andy
Title: Re: Retlas "Manchester" Dynamo
Post by: Chipmaster on November 13, 2020, 09:25:29 PM
This afternoon I completed the bearings. The bronze bearings were reduced from 2.1/2" to 1.1/2" - the distance between the oil collecting grooves in the pedestals. 5/16" Slots were then milled across the centre of the bearings down to about half their diameter. This gave ample  contact to have the oil rings rotate with the shaft.

 (https://live.staticflickr.com/65535/50598386031_be904d8f91_z.jpg) (https://flic.kr/p/2k6cXm4)IMG_2349 (https://flic.kr/p/2k6cXm4) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

In this picture looking through the bearing the oil ring is resting in the slot
(https://live.staticflickr.com/65535/50597641818_91f82489e6_z.jpg) (https://flic.kr/p/2k6997N)IMG_2356 (https://flic.kr/p/2k6997N) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

(https://live.staticflickr.com/65535/50597641773_35a6eeb185_z.jpg) (https://flic.kr/p/2k69972)IMG_2363 (https://flic.kr/p/2k69972) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

The bronze bearings can be pushed into the pedestal casting by firm finger pressure, 4BA grub screws keep them in place at the moment but I may use a low strength grade of Loctite for the final assembly.

(https://live.staticflickr.com/65535/50598506387_d77e08a82e_z.jpg) (https://flic.kr/p/2k6dz8a)IMG_2366 (https://flic.kr/p/2k6dz8a) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

Andy 
 
Title: Re: Retlas "Manchester" Dynamo
Post by: Johnmcc69 on November 13, 2020, 10:11:42 PM
 :ThumbsUp:
 Looking good Andy! Lot's to be learned here!
  :popcorn:
 John
Title: Re: Retlas "Manchester" Dynamo
Post by: Alyn Foundry on November 14, 2020, 03:15:06 PM
Some " hand chased " lubrication grooves to finish Andy ?

 :)
Title: Re: Retlas "Manchester" Dynamo
Post by: Chipmaster on November 14, 2020, 09:22:38 PM
Thanks John, reckon I'm always learning with these projects.

Hi Graham, I was thinking along the same lines myself. I'll see how the bearings perform in action in order to see if oil grooves are needed. Is there an established pattern for oil grooves?
However, if a reasonable amount of oil appears to be travelling through the bearing I'll leave it alone.

Here's a view of the dynamo with the oil rings on show.

 (https://live.staticflickr.com/65535/50602169796_12ff09564d_z.jpg) (https://flic.kr/p/2k6xm8o)IMG_2368 (https://flic.kr/p/2k6xm8o) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

Then I took it apart to machine the section of pedestal that the Armature Reaction Compensator will be mounted on. A smooth surface will be necessary to enable rotation of the compensator for fine tuning.

Great care was necessary because of the close proximity of the 1.160" diameter oil collection groove inside the pedestal, machine  too much off the external surface and the end of the pedestal casting would fall off!

(https://live.staticflickr.com/65535/50602285067_f3264c628b_z.jpg) (https://flic.kr/p/2k6xWoP)IMG_2372 (https://flic.kr/p/2k6xWoP) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

(https://live.staticflickr.com/65535/50602285027_d6e90932ec_z.jpg) (https://flic.kr/p/2k6xWo8)IMG_2373 (https://flic.kr/p/2k6xWo8) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

I settled for an od of 1.2", some slight pitting remained on a small section which shouldn’t have any detrimental effect, after all the compensator won't be moved frequently.

(https://live.staticflickr.com/65535/50602284952_f0e85d0d82_z.jpg) (https://flic.kr/p/2k6xWmQ)IMG_2374 (https://flic.kr/p/2k6xWmQ) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

(https://live.staticflickr.com/65535/50602284907_7c99e9e6ed_z.jpg) (https://flic.kr/p/2k6xWm4)IMG_2375 (https://flic.kr/p/2k6xWm4) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

Andy
Title: Re: Retlas "Manchester" Dynamo
Post by: MJM460 on November 15, 2020, 07:37:29 AM
Great detailing on the oil ring lubrication.  I am so glad that you did not resort to plain bushes.

Now you just need a lip type oil and dust seal each end.  I wonder if these can be bought as commercial items of a suitable size.

I am really enjoying the whole build.

MJM460

Title: Re: Retlas "Manchester" Dynamo
Post by: Alyn Foundry on November 15, 2020, 11:29:35 AM
Where " ring lubrication " was used there was almost always a " thrower " ring fitted too. These rings were made to form a conical shape and as the oil left the bearing it would naturally try to find the highest point. Centrifugal force would then " throw " the oil into the groove and be returned to the reservoir.

In the " old days " thick Felt would be used to gently seal the openings to prevent both leakage and ingress of dirt.

I'm curious about the next phase Andy, obviously a nice Brass casting for the Armature reaction compensator would have been most helpful ! For " one offs " you can really appreciate the kind of work that Jason shows from the CNC department.

Cheers Graham.
Title: Re: Retlas "Manchester" Dynamo
Post by: Chipmaster on November 15, 2020, 12:23:04 PM
Hi MJM460 and Graham,
Lipped oil seals are available with an od of 1” and I’d of 0.75” so they are an option if necessary.
It just so happens that last week I was thinking of using felt washers and ordered some from this firm,

https://hardy-hanson.co.uk/product/1-od-x-3-4-id-x-1-5mm-thick-felt-washers/

At the price of £2.50 inclusive for 200 it’s worth having a go.

For the Armature Reaction Compensator I intend to machine a brass clamping ring 1.2” id and approximately 1.5” od with lugs either side of a gap. This ring will be silver soldered to the diamond shaped body of the compensator along the lines of the ignition timing adjuster I made for the Retlas engine in the picture below. I’m waiting for some 1/4” thick brass plate that I ordered a week ago, no cnc here I can shape the brass plate with the tools I have.

Andy



Title: Re: Retlas "Manchester" Dynamo
Post by: Jasonb on November 15, 2020, 01:11:52 PM
It's interesting that the trouble is taken to catch any oil that migrates outwards with the groove and drain hole in the outer side or the ring but there is nothing to catch oil moving towards the armature. I have an vertical Hit & Miss that uses the similar groove to return oil from the outside of the bearing all the way back into the crankcase which is OK but this could get a bit messy.

Not sure if a generator would have quite such as fancy reaction compensator as you see on some of the bi-polar fans etc which can get quite elaborate but it would not be hard to make those two triangles look a bit more interesting even if it were only drilling three holes and joining up the dots to get a triangular cut out that could be milled of filed.

had the bearings been split ones it's not so hard to machine oil grooves with a flycutter or between ctrs boring bar but I wonder if it's really needed on the model.
Title: Re: Retlas "Manchester" Dynamo
Post by: Alyn Foundry on November 15, 2020, 01:46:49 PM
Hi Jason.

The bearing housings have " catchers " on either side, I think Andy posted a picture on the previous page.

With DC motors the brushgear is, in most cases, permanently fixed by the manufacturer. With a DC generator, particularly of early design the operator had to manually find the " sweet spot " where commutator arcing was minimal. This is because the magnetic flux gets twisted by the electrical load current and in doing so moves the maximum voltage developed in the armature to different commutator segments.

As time progressed they started fitting " interpoles " these additional coils placed at 90 degrees from the main poles had the load current pass through them. This had the effect of straightening the main magnetic flux back to the correct place for the now " fixed " brushgear.

Cheers Graham.
Title: Re: Retlas "Manchester" Dynamo
Post by: Chipmaster on November 15, 2020, 01:56:25 PM
Hi Jason I hope I understand your point about there being nothing to catch oil moving towards the armature.
 There is, I cut the oil returns on each side of the pedestals - four in total.

Regarding the reaction compensators on generators, the few pictures on the Internet of vintage dynamos appear to have nicely crafted compensators, I attach some pictures below. I assume these are dynamos not motors.

Andy
Title: Re: Retlas "Manchester" Dynamo
Post by: Alyn Foundry on November 15, 2020, 02:14:42 PM
Some absolute beauties there Andy.... And yes, all dynamos.

The middle one had me reminiscing, most of the big water pumps I worked on were made by Mather and Platt of Manchester. The largest were powered by 450 HP electric motors made by British Thopmson-Houston or BTH for short.

Cheers Graham.
Title: Re: Retlas "Manchester" Dynamo
Post by: Alyn Foundry on November 15, 2020, 03:43:53 PM
Obviously, looking ahead Andy.   ;)

I found this on eBay....

https://www.ebay.co.uk/itm/Gold-Silk-Covered-Cable-Double-Insulated-3-Core-x-0-75mm-Sold-Per-Metre/310793117501?hash=item485cb69f3d:g:PiEAAOxyXDhSgR4R

Coincidentally the seller backs onto the road where my Uncle had his auto electrical business. The very place I saw an " Armature growler " tester for the very first time.

Cheers Graham.
Title: Re: Retlas "Manchester" Dynamo
Post by: Chipmaster on November 15, 2020, 05:43:52 PM
That wire has an attractive retro look Graham, thanks.

Now for some oil ring action,

https://www.youtube.com/watch?v=3Rt8hJyXYaw

The pedestal oil chamber was empty during the video, it gets a bit messy when dismantling which happens frequently at the moment.

I made two collars this afternoon to restrict end float. They are either side of the pedestal bearing, made of mild steel, for retention each collar has two 2BA grub screws at 120 degrees.

Here's another pair of vintage dynamos in a picture found on the Internet.

(https://live.staticflickr.com/65535/50606012117_9358f30ea0_c.jpg) (https://flic.kr/p/2k6T3ji)Two bipolar dynamos (https://flic.kr/p/2k6T3ji) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

Andy
 
Title: Re: Retlas "Manchester" Dynamo
Post by: Roger B on November 15, 2020, 07:52:51 PM
I do love all these old machines  :)  :)  :wine1: I await your first trials with interest. I have been using commercial permanent magnet motors as loads for my engines and it is interesting how bad the declared efficiencies are  ::)
Title: Re: Retlas "Manchester" Dynamo
Post by: Alyn Foundry on November 16, 2020, 11:47:08 AM
Good morning Andy.

Some more beauties from when the " Art " was young.

You can see that wood was used to make the sheaves for the coil bobbins perhaps this " wood " be the way to go?  :)

Some nice looking hardwood turned and polished then pressed onto a plastic sleeve that slips over the cores. You could also turn a register near the outside diameter to place the thick cardboard to form the outer serving. Take a look at the armature on the left, with its string serving, that's exactly what Vincent did with his.

Thanks again for presenting this build log, it shows a different side of Alyn Foundry.

Cheers Graham.
Title: Re: Retlas "Manchester" Dynamo
Post by: Chipmaster on November 18, 2020, 08:51:47 PM
I agree with Graham that the polished wooden sheaves for the coil bobbins look attractive in the picture of the old Edison Bipolar Dynamos so I made four this afternoon. A piece of what I believe is teak which came from a ten foot length of school laboratory work top that I acquired about 45 years ago is the toughest wood I have and I happened to have a hole saw that produced 2.75" cores, just about the right diameter.

 (https://live.staticflickr.com/65535/50618319226_306e252482_z.jpg) (https://flic.kr/p/2k7Y7MQ)IMG_2395 (https://flic.kr/p/2k7Y7MQ) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

The centre was drilled and bored out to 40mm to fit over some waste pipe that also slides over the field coil cores.

(https://live.staticflickr.com/65535/50618319111_9a32c78bbe_z.jpg) (https://flic.kr/p/2k7Y7KR)IMG_2394 (https://flic.kr/p/2k7Y7KR) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

(https://live.staticflickr.com/65535/50618319206_7b0831d817_z.jpg) (https://flic.kr/p/2k7Y7Mu)IMG_2402 (https://flic.kr/p/2k7Y7Mu) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

The outer edges of the flanges were rounded over with a form tool.

(https://live.staticflickr.com/65535/50618319151_fb2e5b25d6_z.jpg) (https://flic.kr/p/2k7Y7Lx)IMG_2406 (https://flic.kr/p/2k7Y7Lx) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

Then parted off

(https://live.staticflickr.com/65535/50617583488_26b4e332ab_z.jpg) (https://flic.kr/p/2k7Um5G)IMG_2403 (https://flic.kr/p/2k7Um5G) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

The wooden flanges slide over the plastic waste pipe, I haven't glued them together yet.

(https://live.staticflickr.com/65535/50618427522_28fa49d662_z.jpg) (https://flic.kr/p/2k7YEZ1)IMG_2398 (https://flic.kr/p/2k7YEZ1) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

Here are some pictures of the bobbins on the dynamo.

(https://live.staticflickr.com/65535/50618427682_2325c37724_z.jpg) (https://flic.kr/p/2k7YF2L)IMG_2407 (https://flic.kr/p/2k7YF2L) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

(https://live.staticflickr.com/65535/50618427412_7d4fce6a96_z.jpg) (https://flic.kr/p/2k7YEX7)IMG_2410 (https://flic.kr/p/2k7YEX7) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

200 felt washers were delivered today, I might use a few as dust seals and they may help to stop oil escaping from the bearings.

(https://live.staticflickr.com/65535/50617583023_9f0fdfaf46_z.jpg) (https://flic.kr/p/2k7UkWF)IMG_2418 (https://flic.kr/p/2k7UkWF) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr
(https://live.staticflickr.com/65535/50617582993_579ebdf781_z.jpg) (https://flic.kr/p/2k7UkWa)IMG_2419 (https://flic.kr/p/2k7UkWa) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

I'm almost ready to wind the two field coils, the brass to make the Armature Reaction Compensator was delivered today, better buy some brass gauze for the brushes.

Andy

 
 
Title: Re: Retlas "Manchester" Dynamo
Post by: MJM460 on November 18, 2020, 09:16:46 PM
It makes sense that felt disks would be used as shaft wipers and dust seals in the period of this machine.  The lip seals I am more familiar with would be much more recent technology.

Good to see that you were able to purchase them, even if you do now have many lifetimes supply.

Nice job on the teak ends for the wire bobbins.  That bench top looks like it may have been made from alternating layers like ply wood, but with teak layers.  Interesting.  Glad it didn’t go in the bin.

MJM460
Title: Re: Retlas "Manchester" Dynamo
Post by: Chipmaster on November 18, 2020, 09:50:37 PM
Hello MJM, yes the lip seals would be from another era. I was pleasantly surprised that so many felt washers could be bought so cheaply.
The old ten foot long laboratory benchtop consisted of 6" wide planks joined by lengths of plywood glued into grooves along the edges. I made a table with half of the benchtop and stored the rest. It is beautiful wood but I had to work around the gas tap holes and it needed a lot of scraping and sanding to get rid of the initials scrawled into the surface.
The laminate appearance was caused by the action of the hole saw - I had to stop every now and then when it started smoking!

Andy 
Title: Re: Retlas "Manchester" Dynamo
Post by: Twizseven on November 18, 2020, 10:43:48 PM
Andy,

That's going to be a beautiful model when completed.

Colin
Title: Re: Retlas "Manchester" Dynamo
Post by: Chipmaster on November 19, 2020, 09:50:45 AM
Thanks Colin, I feel pretty confident at this stage. At least there aren’t the concerns with piston fits and sealing valves that we have with engines. Achieving a vintage appearance for the field coils is my current task.

Andy
Title: Re: Retlas "Manchester" Dynamo
Post by: Chipmaster on November 24, 2020, 09:27:20 PM
I have made progress with the field coil bobbins or reels, the teak flanges were glued to the white polyethylene waste pipe using an aliphatic glue which did the job on a test piece. After assembling the bobbins I gave the teak a coat of Rustins Sanding Sealer.
Here are my bobbins left drying on a broomstick
(https://live.staticflickr.com/65535/50642617062_7fa53126b1_z.jpg) (https://flic.kr/p/2ka7DG3)IMG_2453 (https://flic.kr/p/2ka7DG3) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

(https://live.staticflickr.com/65535/50642617167_29813b559e_z.jpg) (https://flic.kr/p/2ka7DHR)IMG_2454 (https://flic.kr/p/2ka7DHR) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

A narrow radial slot has been sawn in the inside of each flange as a route for the copper wire leading to the first layer of the windings. A small rebate was also cut around the inside of each flange which should help to achieve a neat finish when the coils have an outer layer of string serving.

I also started making the Armature Reaction Compensator.

(https://live.staticflickr.com/65535/50642747287_b7fe969f1a.jpg) (https://flic.kr/p/2ka8jpi)Armature Reaction Compensator (https://flic.kr/p/2ka8jpi) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

This is going to be fabricated.
First a brass ring 1.5" od 1.2" id x 0.375" machined to be a sliding fit over the end of the pedestal.

(https://live.staticflickr.com/65535/50642561521_cdc3e5ed2c_z.jpg) (https://flic.kr/p/2ka7nbr)IMG_2443 (https://flic.kr/p/2ka7nbr) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

Followed by a piece of 1/4" thick brass plate to be silver soldered to the brass ring.

(https://live.staticflickr.com/65535/50642639887_0532a6260b_z.jpg) (https://flic.kr/p/2ka7Ltz)IMG_2437 (https://flic.kr/p/2ka7Ltz) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

(https://live.staticflickr.com/65535/50642561556_78e5d7fe30_z.jpg) (https://flic.kr/p/2ka7nc3)IMG_2442 (https://flic.kr/p/2ka7nc3) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

(https://live.staticflickr.com/65535/50641779678_500b6ec128_z.jpg) (https://flic.kr/p/2ka3mLo)IMG_2445 (https://flic.kr/p/2ka3mLo) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

(https://live.staticflickr.com/65535/50641779528_29008c25a3_z.jpg) (https://flic.kr/p/2ka3mHN)IMG_2447 (https://flic.kr/p/2ka3mHN) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

(https://live.staticflickr.com/65535/50642617252_a28bafd576_z.jpg) (https://flic.kr/p/2ka7DKj)IMG_2448 (https://flic.kr/p/2ka7DKj) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

(https://live.staticflickr.com/65535/50642617217_b7de35595d_z.jpg) (https://flic.kr/p/2ka7DJH)IMG_2449 (https://flic.kr/p/2ka7DJH) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

That was it for today.

Andy
Title: Re: Retlas "Manchester" Dynamo
Post by: Alyn Foundry on November 24, 2020, 10:15:54 PM
Those bobbins really look the " business " Andy, well done.     :ThumbsUp:

This is going to be one of the nicest Retlas dynamos I've ever seen.

Cheers Graham.

Edit....

Re your email....

http://www.modelenginemaker.com/index.php/topic,9323.msg228168.html#msg228168
Title: Re: Retlas "Manchester" Dynamo
Post by: Jasonb on November 25, 2020, 07:21:11 AM
Silk, now that is posh ;)

I've used these people for period lighting cable in the past, they don't do singles but you can untwist the 2 core

https://www.urbancottageindustries.com/light-fixtures/lighting-and-power-cable

Also look at some of the vintage and classic car electrical suppliers who will have cotton braided single strand in various gauges, this is what I use on the Hit & Miss engines
Title: Re: Retlas "Manchester" Dynamo
Post by: Bluechip on November 25, 2020, 09:45:53 AM
Wires ?

https://www.wires.co.uk/

D.
Title: Re: Retlas "Manchester" Dynamo
Post by: Chipmaster on November 27, 2020, 09:32:11 PM
Wire?
Yes D thanks for the information.
I have their copper wire for making the field coils,
(https://live.staticflickr.com/65535/50567366361_5651077051.jpg) (https://flic.kr/p/2k3sYha)IMG_2239 (https://flic.kr/p/2k3sYha) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr
 
I had also noticed that they sell the silk and cotton covered wire but haven't decided which wire to use yet, I have been referred to a few sources. I would like to wind up curly leads the same as seen in this picture of an early Crompton dynamo copied from the Queensland Energy Exhibition Centre website.

 (https://live.staticflickr.com/65535/50654280996_ce4af849af_o.jpg) (https://flic.kr/p/2kb9qYm)EARLY CROMPTON DYNAMO (https://flic.kr/p/2kb9qYm) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

Over the last couple of days I have continued fabricating the Armature Reaction Compensator by silver soldering pieces of brass together then using a slitting saw to make a gap for a pinch bolt.

(https://live.staticflickr.com/65535/50653672347_6475aaee56_z.jpg) (https://flic.kr/p/2kb6j3p)IMG_2460 (https://flic.kr/p/2kb6j3p) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr
(https://live.staticflickr.com/65535/50653672272_5b0275e34d_z.jpg) (https://flic.kr/p/2kb6j27)IMG_2467 (https://flic.kr/p/2kb6j27) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr
(https://live.staticflickr.com/65535/50652844288_02da4d90ba_z.jpg) (https://flic.kr/p/2kb24Tw)IMG_2463 (https://flic.kr/p/2kb24Tw) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

While awaiting delivery of copper braid for the brushes it seems I should get on and wind the field coils. Mounting the brushes should be straightforward and I might have a go at making a wooden handle and covers for the oil chambers.

Can anyone advise whether I should limit the number of turns or just keep going until I run out of copper wire. I calculate that I have enough wire to put between 300 - 350 turns on each coil, also assume the number of turns on each field coil should be the same. I bought this stroke counter from RS Components which I intend to use to count the windings.

(https://live.staticflickr.com/65535/50653614683_c37e4a2bec_z.jpg) (https://flic.kr/p/2kb61Uc)IMG_2490 (2) (https://flic.kr/p/2kb61Uc) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

Andy


Title: Re: Retlas "Manchester" Dynamo
Post by: Roger B on November 28, 2020, 08:06:45 AM
Use all the wire or as much as you can fit on the bobbins. More wire will mean a higher resistance and less current through the coils for a given voltage but there will be more turns so that the ampere turns value will be much the same. Less current through the field coils will mean more for the load and less heating of the coils. The downside is you may need a higher voltage to achieve full excitation, but without full details of the system it will be hard to estimate. You also have the option to connect the coils in series or parallel (make sure that the phasing is correct  ::) )
Title: Re: Retlas "Manchester" Dynamo
Post by: Chipmaster on November 28, 2020, 09:54:06 AM
Thanks Roger, I hope to be posting pictures of the wound coils later today.

Andy
Title: Re: Retlas "Manchester" Dynamo
Post by: Chipmaster on November 28, 2020, 09:13:18 PM
The field coils were wound using my lathe this afternoon,

The set up, first a video taken at the wrong angle.

https://www.youtube.com/watch?v=pwbh7Ar3dRI

(https://live.staticflickr.com/65535/50657923627_80820994ba_z.jpg) (https://flic.kr/p/2kbt6Nk)IMG_2494 (2) (https://flic.kr/p/2kbt6Nk) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

(https://live.staticflickr.com/65535/50657832816_a2723c9ce4_z.jpg) (https://flic.kr/p/2kbsCNC)IMG_2496 (https://flic.kr/p/2kbsCNC) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

I used a hot glue gun to keep the copper wire in the wooden flange so I could start with a little tension on the wire simply holding it between finger and thumb.

For the first coil the lathe was set to it's slowest speed of 35 rpm, I was expecting to have enough wire for 350 turns on the coil taking about ten minutes. The first three or four layers were very neat not a turn out of place but as the job progressed I couldn't maintain the standard and things became untidy. As the stroke counter went past 400 and there was plenty of wire left on the spool it was clear that my elementary calculations were rubbish. After about 25 minutes the copper wire ran out and I had just over 800 turns on the coil. As I had overshot my estimate by nearly 500 turns I was concerned that I had gone too far. I phoned Graham (Alyn Foundry) for assurance that 800 turns was ok and he agreed with Roger B, "Use all the wire or as much as you can fit on the bobbins".

Winding the second coil went the same way as the first first few layers rather neat then it went a bit free form, not a tangle but I forgot to take picture before I covered it up with masking tape.  :embarassed:

I tested the coils with a 12v battery, they are certainly powerful electro magnets.

Here are the coils back on the dynamo.

(https://live.staticflickr.com/65535/50657832796_0226957745_z.jpg) (https://flic.kr/p/2kbsCNh)IMG_2497 (https://flic.kr/p/2kbsCNh) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

(https://live.staticflickr.com/65535/50657923522_dfe7582bb7_z.jpg) (https://flic.kr/p/2kbt6Lw)IMG_2498 (https://flic.kr/p/2kbt6Lw) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

They will receive their cosmetic treatment ( cardboard and string serving) after I have attached suitable lead out wires.

Andy

Title: Re: Retlas "Manchester" Dynamo
Post by: Dave Otto on November 28, 2020, 09:27:27 PM
Nice progress Andy!

Dave
Title: Re: Retlas "Manchester" Dynamo
Post by: Jasonb on November 29, 2020, 07:02:52 AM
It's coming together well. I had similar problems when I did my little electric engine with the first couple of layers going where you want and then it starts to go down hill as the wire wants to drop into the "U" formed by the previous layer rather than run over the top.
Title: Re: Retlas "Manchester" Dynamo
Post by: Alyn Foundry on November 29, 2020, 11:29:10 AM
Does it motor yet, does it motor yet ??  :)

Seriously, the coils look great Andy. Don't forget to mark up the starts and finishes so you won't get the polarities mixed up. Are you going to bring the pairs out of a single hole? Or one at either end?

Because you have some room to spare before the final serving you can now firmly secure the windings with either PVC electrical tape, hot glue or even Shellac and Indian cloth tape ( purist approach ) lol.

The important point is a decent electrical connection between the solid Copper magnet wire and the more flexible output wires. I'd suggest soft solder but please use the 60% Tin 40% Lead  ( TinMan's ) grade. Once soldered sleeve and firmly anchor the connection to the bulk of the coil. Any wire that carries a current will try to move towards a magnetic field, a firm, mechanically strong fixing is recommended.

Cheers Graham.
Title: Re: Retlas "Manchester" Dynamo
Post by: Chipmaster on November 29, 2020, 02:49:22 PM
Thanks for the comments Dave and Jason - nice to know that someone else had the same experience winding coils.

Patience patience Graham  :)
I had an unsuccessful motor test this morning. One field coil was connected to a 12v battery and wires from a separate battery were held against the opposite sides of the commutator. The armature certainly jerked but the sparks would have damaged the commutator if I’d persisted. I have ordered some copper braid and Tufnol so I’ll test it again when the dynamo has the proper brush gear.
The solid copper and flexible output wires will be soldered together. I have cored 60/40 solder, is that ok or should I use plain 60/40 blowpipe solder ? The pairs of wires emerge together from the top of the coils, at present it is easy to identify each wire but I appreciate the need to ensure they aren’t mixed up when the windings are secured and served.
I have an old Hammant and Morgan model railway controller left over from my childhood, using a lower and variable voltage would lower the risk of damage to the commutator, would that be suitable for the motor test?

Andy
Title: Re: Retlas "Manchester" Dynamo
Post by: Alyn Foundry on November 29, 2020, 03:41:57 PM
Hi Andy.

Yes, that flux cored 60/40 Tin/Lead solder will be ideal.

You could definitely try using your variable DC controller but I fear the current demand might be too great, but it's worth a shot.

When all is done the voltage and associated current will be shared between the armature and field for motoring and should reduce the arcing that you're seeing now. But from your description I would say you're well on the way to a working DC machine.    :ThumbsUp:

Cheers Graham.
Title: Re: Retlas "Manchester" Dynamo
Post by: Roger B on November 29, 2020, 03:55:25 PM
Copper mesh brushes will always arc. The resistance of graphite brushes is chosen to smooth the current transition between the commutator segments.

Depending on the friction you will probably need 1 or 2 amps to get it motor so the H+M controller may work.

Layer winding of coils is tricky. The wire needs to be guided very close in and most modern systems use CNC machine principles to control the pitch and more importantly the reversal points.

Long ago we rewound the field coils of a C40 dynamo as a series motor for a battery electric locomotive. My father decided to try a wire twice the size of the original which reduced the resistance of the coils to 1/4 of the original value. This ran on 24V with currents between 5 and 25A.
Title: Re: Retlas "Manchester" Dynamo
Post by: Don1966 on November 29, 2020, 05:24:54 PM
I have no clue to how much current you will be drawing with your motor but it is important to make the brush holder adjustable for proper commutation. The neutral plane setting is were you have the least sparking and the induced short circuit current created because of brushes being in the wrong plane. This will reduced the sparking to a minimum. Proper brushes and brush seating are also important.


Regards Don
Title: Re: Retlas "Manchester" Dynamo
Post by: Chipmaster on November 29, 2020, 05:40:56 PM
It motors !

https://www.youtube.com/watch?v=J5pYfgjsZZs

I couldn't resist having another go and after a few sparks off it went on only one field coil.
Thanks for the advice Graham, Roger and Don - better not do any more of this jury rigged stuff in order to preserve the commutator. However, it seems more likely that the dynamo will work. The field coil was luke warm having been powered for a few minutes, I wonder if that's because only one was connected?

Rather pleased

Andy 
Title: Re: Retlas "Manchester" Dynamo
Post by: Dave Otto on November 29, 2020, 05:47:55 PM
Congrats!
That's pretty cool!

Dave
Title: Re: Retlas "Manchester" Dynamo
Post by: Alyn Foundry on November 29, 2020, 06:36:27 PM
Well done Andy.... :ThumbsUp:

Just a few steps away from a Dynamo.

If it motors it WILL generate.

Cheers Graham.
Title: Re: Retlas "Manchester" Dynamo
Post by: Roger B on November 29, 2020, 07:02:28 PM
 :ThumbsUp: :ThumbsUp: :ThumbsUp:  :wine1:
Title: Re: Retlas "Manchester" Dynamo
Post by: Don1966 on November 29, 2020, 07:38:43 PM
 :drinking-41:


Don
Title: Re: Retlas "Manchester" Dynamo
Post by: Chipmaster on December 11, 2020, 09:38:10 PM
A little progress - mainly cosmetic.
After winding approximately 800 turns on to each of the field coils the surfaces were rather uneven. They started off well but it was impossible to maintain even layers.
I treated the windings with several coats of shellac in order to consolidate the coils.

(https://live.staticflickr.com/65535/50692624777_a0c2bb12d8_z.jpg) (https://flic.kr/p/2kewXf2)IMG_2574 (2) (https://flic.kr/p/2kewXf2) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

The next treatment was to add a couple of layers of multi purpose filler to form a level surface.
 
(https://live.staticflickr.com/65535/50691801158_8375e7a647_z.jpg) (https://flic.kr/p/2kesJpG)IMG_2575 (2) (https://flic.kr/p/2kesJpG) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

Followed by plastic bands cut from 500cc hand soap dispensers (Tesco and Baylis & Harding) which were cut to a close fit and the ends joined by a piece of insulating tape. Retro cloth covered auto flex was soldered on to the ends of the windings at this stage.

(https://live.staticflickr.com/65535/50706547186_33c87187bb_z.jpg) (https://flic.kr/p/2kfLiTy)IMG_2590 (https://flic.kr/p/2kfLiTy) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

I was then ready to serve the coils with polished flax stitching twine sourced from my wife's upholstery kit. A hot glue gun was used to stick down the free ends and add support to the 0.75mm copper wire as it emerged from the coils.

(https://live.staticflickr.com/65535/50705812438_9c3712fcec_z.jpg) (https://flic.kr/p/2kfGxtu)IMG_2593 (2) (https://flic.kr/p/2kfGxtu) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

Ronseal wood stain was painted over the string to make it more durable and enhance the appearance, additional coats may be necessary.

(https://live.staticflickr.com/65535/50706539038_d9a2d86398_z.jpg) (https://flic.kr/p/2kfLgt5)IMG_2596 (2) (https://flic.kr/p/2kfLgt5) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

(https://live.staticflickr.com/65535/50707274166_cc3dca6039_z.jpg) (https://flic.kr/p/2kfQ2ZG)IMG_2597 (2) (https://flic.kr/p/2kfQ2ZG) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

The piece of sapele sitting on top of the upper pole piece was shaped with a router, it will be fitted with brass terminals and the brass 'Retlas Dynamo' plaque.
I have also added a few brass and Tufnol parts to the armature reaction compensator which will carry the brushes, but haven't decided on the type of brush holder yet. There are plenty in old photographs to copy. 

(https://live.staticflickr.com/65535/50707497647_c0d0a56c9e_z.jpg) (https://flic.kr/p/2kfRbqP)IMG_2580 (2) (https://flic.kr/p/2kfRbqP) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

I'm planning to use copper braid supported by brass strip, the braid is very flexible.

(https://live.staticflickr.com/65535/50707497652_196ff95d2f_z.jpg) (https://flic.kr/p/2kfRbqU)IMG_2577 (3) (https://flic.kr/p/2kfRbqU) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

Andy


Title: Re: Retlas "Manchester" Dynamo
Post by: Alyn Foundry on December 12, 2020, 11:35:26 AM
Good morning Andy.

WOW what a difference, when finished it could become a worthy exhibit at any Technology museum.

Are you going to try and " serve " the armature ends in a similar fashion?

I noticed that you'd insulated both brush support pillars, I'm in favour of that because it means the frame is electrically isolated. Not much of a problem at 12 Volts but could be dangerous at higher voltages.

Eagerly awaiting the rather tricky portion, the brush carriers....

Cheers Graham.
Title: Re: Retlas "Manchester" Dynamo
Post by: Chipmaster on December 16, 2020, 09:24:10 PM
The model dynamo is quite heavy so I fitted a paid of lifting eyes to mimic full size practice, size M8 stainless steel from first4magnets.com. The eye of the M8 size is large enough for my index finger. I don't have any M8 threading kit so I bored them out and re threaded them 3/8 Whitworth. The heads of the two 1/2" bolts holding the upper pole casting were reduced to a height of 1/8" then bored and threaded 1/4" Whit. Recesses were routed in the underside of the wood to accommodate the bolt heads. Two brass stepped studs threaded 1/4 and 3/8" Whit were made to secure the woodwork and the lifting eyes. I used Brass and stainless steel to avoid the parts becoming magnetic which might cause problems.

(https://live.staticflickr.com/65535/50711318961_94e76ab525_z.jpg) (https://flic.kr/p/2kgbLnx)IMG_2606 (https://flic.kr/p/2kgbLnx) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

(https://live.staticflickr.com/65535/50711402997_76c6cef943_z.jpg) (https://flic.kr/p/2kgccmr)IMG_2607 (2) (https://flic.kr/p/2kgccmr) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

(https://live.staticflickr.com/65535/50711318946_9aa8908e74_z.jpg) (https://flic.kr/p/2kgbLnh)IMG_2612 (2) (https://flic.kr/p/2kgbLnh) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

I also made four brass terminals, in this picture they are just sitting on the woodwork alongside the brass plaque that there is just enough room for.

 (https://live.staticflickr.com/65535/50724361321_e06b2a1b2d_z.jpg) (https://flic.kr/p/2khkBpP)IMG_2653 (2) (https://flic.kr/p/2khkBpP) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

Then on to the brush carriers that Graham is eagerly awaiting.

I have looked at several pictures of vintage dynamos that appear to use metallic braid for brushes and the carriers seemed straightforward. I used 3/8" square and 9/16" diameter brass bar milled and silver soldered together to form the slots for the brushes.

 (https://live.staticflickr.com/65535/50724360931_1b2208b5e6_z.jpg) (https://flic.kr/p/2khkBi6)IMG_2655 (https://flic.kr/p/2khkBi6) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

The copper braid I chose being very soft and fine which I thought would go easy on the commutator. However, I find it is prone to fraying. So, I soldered up the ends using a 120 watt soldering iron, I tried using a flame but it made a mess of it. The braid is tubular so I was able to put a strip of brass inside to stiffen it. There is space in the carriers for extra strips of brass should more support be required.

 (https://live.staticflickr.com/65535/50724447497_94d928b33e_z.jpg) (https://flic.kr/p/2khm42B)IMG_2656 (https://flic.kr/p/2khm42B) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

(https://live.staticflickr.com/65535/50726686423_d50ece5a39_z.jpg) (https://flic.kr/p/2khxwzM)IMG_2665 (2) (https://flic.kr/p/2khxwzM) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

 (https://live.staticflickr.com/65535/50727415921_6541be9a26_z.jpg) (https://flic.kr/p/2khBgrk)IMG_2666 (2) (https://flic.kr/p/2khBgrk) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

The copper braid brushes are extra long to allow for wear, I am doubtful they will last long but I'll try them out. I have the appropriate carbon brushes in stock.

To complete the brush carriers I need to drill and thread them so that they are adjustable and held in position on the armature reaction compensator. A means of securing the brushes themselves is also needed.

Andy
Title: Re: Retlas "Manchester" Dynamo
Post by: samc88 on December 16, 2020, 10:57:36 PM
Looking really good, interesting seeing the braid used as brushes, not seen that before.I wonder if it was a cheaper alternative to making carbon brushes back in the early days of electricity
Title: Re: Retlas "Manchester" Dynamo
Post by: Alyn Foundry on December 17, 2020, 02:07:03 PM
Hi Andy.

Sorry for not posting sooner, Internet issues.

I'm not happy about the use of soft solder on the braid in contact with the commutator, this will probably lead to it melting and effectively ruining the segments.

Perhaps a compromise? I have a box full of Copper coated Carbon rods, those used for electric Brazing. They measure roughly 3/8" in diameter. By carefully paring one down you could solder onto the Copper coating and present a Carbon face to the commutator segments?

If you can't find any local to you I could send one on in the post, let me know?

Cheers Graham.
Title: Re: Retlas "Manchester" Dynamo
Post by: Chipmaster on December 17, 2020, 04:14:04 PM
 I agree Graham, only the last 1/8" of the braid is soldered and I intend to adjust the brushes so the solder doesn't contact the commutator. Along the lines of the brushes in these pictures of vintage dynamos copied from the Internet. Do you think that will be ok?

(https://live.staticflickr.com/65535/50730267812_df3587bccb_z.jpg) (https://flic.kr/p/2khRTcS)Dynamo Fabius Henrion Nancy type 000 (https://flic.kr/p/2khRTcS) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

(https://live.staticflickr.com/65535/50730162731_559cc3f303_z.jpg) (https://flic.kr/p/2khRkY8)Clipboard04 4 (https://flic.kr/p/2khRkY8) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

(https://live.staticflickr.com/65535/50730161376_28b289352e_z.jpg) (https://flic.kr/p/2khRkyL)Clipboard03 3 (https://flic.kr/p/2khRkyL) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

Hello Sam,
I don't know the history, I assume Braid was probably used before carbon brushes were developed.

Andy

 
Title: Re: Retlas "Manchester" Dynamo
Post by: Roger B on December 17, 2020, 05:08:04 PM
Looking really good, interesting seeing the braid used as brushes, not seen that before.I wonder if it was a cheaper alternative to making carbon brushes back in the early days of electricity

The clue is in the name. Early dynamos and motors used copper brushes to contact the commutators. These were hard to keep under control but caused less damage to the commutators than solid copper contacts. I think that braids followed this for small units. Interestingly the German word for brushes is Kohlen (carbons). 'Carbon' brushes are quite complex things with often conflicting requirements for electrical resistance and mechanical strength. If the resistance is too high there is too much loss and heating. If the resistance is too low there will be too much sparking when they short two commutator segments.
Title: Re: Retlas "Manchester" Dynamo
Post by: Chipmaster on December 19, 2020, 09:53:19 PM
I have made a few essentials over the last couple of days,

- A wooden and brass handle for moving the Armature Reaction Compensator.
- Knurled brass thumbscrews to clamp the brushes in the carriers
- Extended pins with tommy bars to clamp the carriers in position.
- The tommy bar also serves as a marker for positioning the brush to ensure the soldered ends don’t touch the commutator.

(https://live.staticflickr.com/65535/50737657961_e79f2d982e_z.jpg) (https://flic.kr/p/2kivL3e)IMG_2670 (2) (https://flic.kr/p/2kivL3e) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

(https://live.staticflickr.com/65535/50737657851_7a48fb6041_z.jpg) (https://flic.kr/p/2kivL1k)IMG_2672 (2) (https://flic.kr/p/2kivL1k) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

(https://live.staticflickr.com/65535/50737657886_a4fb07ebc9_z.jpg) (https://flic.kr/p/2kivL1W)IMG_2674 (2) (https://flic.kr/p/2kivL1W) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

(https://live.staticflickr.com/65535/50737765882_1baafae196_z.jpg) (https://flic.kr/p/2kiwj7W)IMG_2676 (2) (https://flic.kr/p/2kiwj7W) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

Making covers for the oil chambers is going to be awkward requiring a lot of fiddling to make something that is easy to check the oil level but won't fall off. I think brass would be in keeping with style.

Andy
Andy
Title: Re: Retlas "Manchester" Dynamo
Post by: Alyn Foundry on December 20, 2020, 11:25:22 AM
It just gets better and better Andy.   :ThumbsUp:

You will be able to use some thin Brass strip to " pair " the Armature to the Field coil terminals. Future testing will ascertain whether you'll need to either parallel or series connect the field coils.

Many stationary engines had a small chain attached to oil covers to enable inspection and reduce the risk of loss, just a thought.

Cheers Graham.
Title: Re: Retlas "Manchester" Dynamo
Post by: Chipmaster on December 21, 2020, 09:20:18 PM
Still work on progress but I had another motoring session this afternoon.

https://www.youtube.com/watch?v=CwwWnn8iapk

I was unable to find the flat belt I wanted to use to drive it as a dynamo, it’s somewhere in my garage  so I’ll have to look again tomorrow.
When connected to a multimeter the dynamo will register almost one volt if the armature is turned quickly by hand so that's encouraging.

Andy


Title: Re: Retlas "Manchester" Dynamo
Post by: Alyn Foundry on December 23, 2020, 06:44:51 PM
I really wish Vincent could see the fruits of your labour Andy, worthy of any museum....

With the brushgear in place I couldn't detect any serious arcing at all. Have you tried altering the position whilst motoring? You would notice a marked increase in arcing and decrease in speed.

Now.... I'm sure all of us " electrically " oriented folk would love some vital statistics.... :)

Applied Voltage and Current consumed whilst motoring. This will provide us with the means to calculate its consumption in Watts.

When the day comes to generate we would like to know the Voltage and Current when applied to a fixed, resistive load, like a lightbulb for instance.

Cheers Graham.
Title: Re: Retlas "Manchester" Dynamo
Post by: Chipmaster on December 23, 2020, 10:06:20 PM
Yes Graham the effect of moving the Armature Reaction Compensator ~ brushes whilst motoring is significant, slows it down, arcing and sounds rough. Am I right in thinking the rotation would be reversed if I moved the brushes far enough? To me it sounds at bit rough or harsh when motoring, what do you think?

I'll have to make a suitable coupling in order to drive the dynamo if it is mounted back on the cross slide of my lathe. Otherwise pulleys will be machined and a suitable rubber flat belt ordered after Christmas.

Andy
Title: Re: Retlas "Manchester" Dynamo
Post by: Admiral_dk on December 25, 2020, 07:26:50 PM
Quote
Am I right in thinking the rotation would be reversed if I moved the brushes far enough?

As far as I know that will be right - think of the extreme case, where you rotate it 180 degree from optimum running, and you effectively have a polarity reversal of the Armature -> opposite running direction.

Really nice work and appearance  :cheers:

Per
Title: Re: Retlas "Manchester" Dynamo
Post by: Alyn Foundry on December 26, 2020, 11:17:34 AM
Merry Christmas Andy.  :cheers:

If memory serves no, the polarity change will affect both Armature and Field coils together.

To reverse the direction you'd need to alter either the field polarity or the armature polarity with respect to each other. With modern, permanent magnet field motors a polarity change will also change the direction.

The machine sounds pretty good to me Andy. I could detect the " ringing " of the oilers but if you're concerned try using a " listening stick " ie a long shafted screwdriver to pinpoint the noise. It might just need a touch of " dynamic balancing "  ;)

All the very best, Graham.
Title: Re: Retlas "Manchester" Dynamo
Post by: Admiral_dk on December 26, 2020, 12:12:24 PM
In my comment you only get the polarity change on the Amature and not the Field Coils => reversal of running direction.
Title: Re: Retlas "Manchester" Dynamo
Post by: Alyn Foundry on December 26, 2020, 01:19:42 PM
In my comment you only get the polarity change on the Amature and not the Field Coils => reversal of running direction.

Hi Per.

The machine is " Shunt " connected so the field and armature are in parallel, a change in armature polarity would see the field do the same.

Cheers Graham.
Title: Re: Retlas "Manchester" Dynamo
Post by: Admiral_dk on December 26, 2020, 06:59:03 PM
Hi Graham

I do not see how this works as I did not change the wires to the Field Coil - but only changed the ones to the Armature in my example -> change in Armature magnetic orientation, but not in the magnetic orientation of the stationary Field Coil ....

I believe that you think I swap the wires / polarity to the whole assembly - but this is not what I do - if I did, I would have to agree with you.

Best wishes
Per
Title: Re: Retlas "Manchester" Dynamo
Post by: Alyn Foundry on January 01, 2021, 03:33:05 PM
Happy new year Andy.

Eagerly awaiting your next instalment, but in the meantime I discovered the only picture of Vincent's Dynamo. You should easily see how primive the MK 1 design was with respect to your own?

Thanks to a group member, Phillip Gallimore who has a complete collection of Stationary Engine magazines he photographed an article that I wrote back in 1991. Amongst the pictures was Vincent's Dynamo.

Just for laughs here's the trio, yours truly on the left and Martin in the middle, Vincent to the right. Placed nicely behind is Martin's 59 BMW with Stieb sidecar. We never knew how he managed to get everything into that chair of his to attend the rallies, the word TARDIS springs to mind.

Cheers Graham.
Title: Re: Retlas "Manchester" Dynamo
Post by: steam guy willy on January 01, 2021, 04:00:21 PM
Nice Photo ..is that an Earles fork BMW behind you ??

Willy
Title: Re: Retlas "Manchester" Dynamo
Post by: Alyn Foundry on January 01, 2021, 04:17:28 PM
Hi Willy.

I'm absolutely clueless, all I remember is that it was built in 1959, oh and a knuckle whitening ride in the chair....

The funniest moment was when Martin rolled onto a Petrol station forecourt with the sidecar literally covered in ice up to its waistline. He discovered that the bottle of Propane he was carrying had, had the valve knocked open and the liquid gas froze everything. The whole station was immediately in panic and the local Fire brigade called to deal with the emergency. Those were the days lol....

Cheers Graham.
Title: Re: Retlas "Manchester" Dynamo
Post by: Chipmaster on January 01, 2021, 07:49:28 PM
Hi Graham, happy new year and thanks for adding the picture of the original Retlas dynamo.
 I haven’t spent much time in my workshop recently due to cold weather. However, whenever I go out there I motor the dynamo and sit looking at it thinking about how to finish it off - I’m still chuffed that it works. It has settled down and runs pretty smoothly.
In particular I’m thinking about sorting out pulleys, what rpm will the dynamo need to be driven at, the direction of rotation, drive belt, covering the oil chambers, tidying up the wiring, filling and painting.
The Retlas dynamo and engine are too long to set up in line on my workbench and it’s too cold to take them outside on my six foot long engine table. I don’t kneel on floors because of replacement knees - problems problems. Perhaps I could set up two Workmates side by side.
I assume to generate the dynamo will have to be driven in the same direction that it is motoring in which case I will need to reverse its rotation to suit the engine if the two are to be in line so I’ll try changing the armature polarity as you suggested.  I’m looking at 1.25” wide x 1mm thick rubber flat belts from Bearings r us that would be long enough to pass around the 10.5” Retlas flywheel and a one or two inch pulley on the dynamo. My Retlas engine also has a 3.5” diameter pulley that may be enough to drive the dynamo and generate a modest voltage. Unfortunately i haven’t measured the Retlas engine revs range, I’d guess four to five hundred rpm which should be enough.
Cheers everybody
Andy

Title: Re: Retlas "Manchester" Dynamo
Post by: Alyn Foundry on January 01, 2021, 09:39:07 PM
Hi Andy.
I'm glad you found the photograph interesting.

The Dynamo will generate in either direction so no worries on that count.

To test Vincent's we used my horizontal milling machine with a pulley and tensioned the belt using the table to hold the machine. Using this means of drive will enable you to get an idea of output by using the different speed settings of the spindle. You will then be able to sort out pulley ratios etc.

Cheers Graham.
Title: Re: Retlas "Manchester" Dynamo
Post by: steam guy willy on January 02, 2021, 02:05:33 AM
Hi Willy.

I'm absolutely clueless, all I remember is that it was built in 1959, oh and a knuckle whitening ride in the chair....

The funniest moment was when Martin rolled onto a Petrol station forecourt with the sidecar literally covered in ice up to its waistline. He discovered that the bottle of Propane he was carrying had, had the valve knocked open and the liquid gas froze everything. The whole station was immediately in panic and the local Fire brigade called to deal with the emergency. Those were the days lol....

Hi, this is my BMW outfit and yes left hand bends are deadly  this was a few years ago and so the excitement is still happening !!!
Title: Re: Retlas "Manchester" Dynamo
Post by: Alyn Foundry on January 02, 2021, 12:13:06 PM
Good morning Willy.

That's a lovely photograph.

You asked if it was an Earls fork, would there have been a largish Black plastic handwheel between the top fork clamps? This is one of the few things I remember about Martin's BMW. The only other thing I remember was that he had fitted an hydraulic brake lever just where your left foot is resting in the photo.
This was for " emergency " stops with a probably seriously overloaded sidecar. As time progressed he fitted a tow hitch and pulled a small, homemade trailer.

The BMW was his main transport having never passed his car driving test. He also ran a Yamaha RD 400 for fun. When his children came along the BMW was changed for a Reliant three wheeler and like all of Martin's vehicles got heavily modified to suit his tastes. The White one turned from a car to a pile of ash in just 20 minutes due to a carb " spit back " despite our valiant efforts with a couple of fire extinguishers.

Cheers Graham.
Title: Re: Retlas "Manchester" Dynamo
Post by: Chipmaster on January 30, 2021, 05:11:15 PM
I haven't been able to spend much time on model engineering lately and my projects are rather delayed.
However, here are some recent pictures of the dynamo mounted on a temporary wooden base. It now has six home made brass terminal posts mounted on the hardwood top, a two inch aluminium pulley and is paired up with the Retlas engine. 

(https://live.staticflickr.com/65535/50888735311_ebfc14bd95_z.jpg)[/url]

(https://live.staticflickr.com/65535/50888854727_48c8e59286_z.jpg) (https://flic.kr/p/2kwS558)

(https://live.staticflickr.com/65535/50888020988_c9b0b88fd0_z.jpg) (https://flic.kr/p/2kwSFz2)

(https://live.staticflickr.com/65535/50888735156_05532fdd75_z.jpg) (https://flic.kr/p/2kwNpJd)

(https://live.staticflickr.com/65535/50888020783_e62d464ba1_z.jpg) (https://flic.kr/p/2kwS52s)

(https://live.staticflickr.com/65535/50888020838_25732150a9_c.jpg) (https://flic.kr/p/2kwNpEF)

Here's a video of the dynamo being driven by the engine.

https://www.youtube.com/watch?v=FN4ARGutcls

The first part of the video shows the dynamo generating approximately six volts when driven by a flat belt on the engine's eleven inch flywheel. My multimeter was set to fifteen volts full scale deflection which can be seen on the video at times - unfortunately the quality of the video is poor. With this set up the engine didn't run well and struggled to pick up speed. The dynamo was running at approximately 575 to 600 rpm when it produced 6 volts, I couldn’t measure current because the fuse in my multimeter had blown.
The engine handled the load with ease when I used it's three and a quarter inch diameter pulley to drive the dynamo. At the reduced speed of 400rpm the dynamo produced approximately two volts / one amp and can be seen powering five 2.2V bulbs wired in parallel.
I didn't know how the dynamo should perform at these low speeds but I found this video of a C40 dynamo being bench tested interesting (same armature that I used). Half way through the video he appears to get 1.39 volts at about 600 rpm and 13 volts at 1,179 rpm. My dynamo appears to doing well by generating 2 volts.

https://www.youtube.com/watch?v=iX-PJZaOOGQ

Occasionally the engine runs away and things get rather hairy as it violently jumps and shakes whatever it’s clamped on. When it runs away the bulbs become much brighter as expected but it’s like a white knuckle ride and I had to kill the engine without noting the meter readings. I haven’t worked out why the Retlas occasionally runs away when it is driving the dynamo. Anyway it’s a good job I fitted a kill button in the ignition circuit. The Retlas engine runs very nicely at speeds of up to 600 rpm so I want to try a larger pulley. A cast iron Mini brake drum will be the basis of a larger pulley attached to the flywheel because there there isn’t much crankshaft projecting beyond the flywheel hub.

Here are two views of the current 3.25" diameter pulley that I machined from cast iron bar followed by the 7" diameter Mini brake drum which cost only £14.75 including post on eBay. Hope this will be an easier way to machine a larger diameter crowned pulley but waiting for delivery of a 125 x 6mm disc to machine a flange that will fit in the centre of the drum.

(https://live.staticflickr.com/3845/33132714312_d49e182bb8_w.jpg) (https://flic.kr/p/2kwNpFC)

(https://live.staticflickr.com/760/32445369614_b7f84d4535.jpg) (https://flic.kr/p/StPPD3)

(https://live.staticflickr.com/65535/50891273702_d9221632fd_w.jpg) (https://flic.kr/p/Rr611o)

(https://live.staticflickr.com/65535/50891157876_c3ab988b92_w.jpg) (https://flic.kr/p/2kx65Du)

Andy
 (https://flic.kr/p/2kx5udu)
Title: Re: Retlas "Manchester" Dynamo
Post by: Roger B on January 30, 2021, 05:32:07 PM
Good stuff  :praise2:  :praise2:  :wine1:

I hope you can sort out why the engine runs away on load  :headscratch: Something in the governor sticking when it is running in a different range  :thinking:

When you get things settled it will be interesting to see the effect of having the field coils in series and parallel  :)
Title: Re: Retlas "Manchester" Dynamo
Post by: Chipmaster on January 30, 2021, 07:05:54 PM
Hello Roger, thanks for your post. There are a few areas both mechanical and electrical that can be tuned so it may take a while for me to achieve optimum results, warmer weather and more time is required.
I prefer to have the engine gently chugging in the range up to 600 rpm so I hope it will cope with the seven inch diameter pulley. I’m happy to have an unstressed engine/dynamo set up powering a string of low voltage light bulbs but I would prefer an output closer to six volts if possible.
The ‘running away’ phenomenon is perplexing, the engine has been a docile runner since I built it a few years ago. I’ll try to focus my handycam on the governor if it runs away again and perhaps watching the video in slow motion will enable me to sort it out. The engine gets much hotter now it’s doing some work, could that be a factor?
Andy
Title: Re: Retlas "Manchester" Dynamo
Post by: Alyn Foundry on January 30, 2021, 07:23:44 PM
Hi Andy.

Absolutely stunning display, that should turn a few heads at any function, very well done.   :cheers:

I'm surprised to read that your Retlas is running so fast but if it's happy at that speed then it's probably OK. So some simple mathematics should get you at the 2000 RPM required at the Dynamo pulley.

You might recall our recent telephone conversation when I asked you about ignition advance and retard? You said it didn't make much difference, that was also a surprise to me. However, you're using an electronic ignition system, could the magnet be too strong so as you can't make adjustments? Just a thought....

Cheers Graham.

Title: Re: Retlas "Manchester" Dynamo
Post by: Chipmaster on January 30, 2021, 09:13:27 PM
Hi Graham, thanks for the posting, nice of you to say that  :ThumbsUp:
It has also become quite a heavy display, not far off taking a small engine to a stationary engine rally thank goodness it won’t need a trailer.

I hope I’m reading my rev counter correctly, I’ll check it tomorrow. Without driving something the engine normally runs at between 350 to 400 rpm if it goes past 600 rpm it becomes too lively. What speed do Retlas’s run at in your experience?

If the man testing his C40 dynamo in the YouTube video generated 13 volts at 1179 rpm I’m hopeful the engine will have the power to run the new seven inch pulley at 400 rpm and drive the two inch dynamo pulley at 1400 rpm ... in theory.

My set up permits adjustment of the ignition timing up to 90° BTDC and about 30°After TDC . While the engine is running I can adjust it to the extent that the engine stops running,  It surprises me the range of ignition timing that the engine will run with. The setting does affect whether you get the knocking/pinking sound or a very docile tick over. I’ll try to stage a video to demonstrate.
Cheers
Andy
Title: Re: Retlas "Manchester" Dynamo
Post by: Twizseven on January 30, 2021, 09:39:47 PM
Andy,

You have made a fantastic job of that dynamo.  It looks stunning with the engine belted up.  Hope you sort your overspeed issues.

Regards,

Colin
Title: Re: Retlas "Manchester" Dynamo
Post by: Chipmaster on January 30, 2021, 10:21:22 PM
Thanks for the compliment Colin.
I'm pleased that it generates, even if it's only a couple of volts at a low speed.

Andy
Title: Re: Retlas "Manchester" Dynamo
Post by: Alyn Foundry on January 31, 2021, 11:48:35 AM
Hi Andy.

Don't worry about a demo, it seems I misunderstood your remarks. The timing is adjustable but doesn't seem to have much effect, correct?

The 350/400 RPM range is good even slower would be better as the crankshaft doesn't have any counterbalance weights.

Cheers Graham.
Title: Re: Retlas "Manchester" Dynamo
Post by: Chipmaster on March 05, 2021, 10:19:39 PM
During the current cold weather it's impractical to use the Retlas gas engine to drive this dynamo in my garage with the doors closed so I decided to test drive the dynamo using a spare single phase electric motor from my Meddings pillar drill. The motor runs at 1500 rpm which seems a reasonable speed for the dynamo. A two inch diameter crowned aluminium pulley was machined and held on the motor shaft by two 1/4" whit grub screws spaced at 120 degrees. The dynamo pulley is also two inches in diameter.

Here's a YouTube video of the dynamo this afternoon March 5th.

https://www.youtube.com/watch?v=bjpAj8K0wtk

The dynamo is turning at 1500 rpm, the old analoge multimeter recorded 10 volts and the LCD multimeter recorded a high of 4.7 amps with the Armature Reaction Compensator adjusted for the optimum output. It was interesting to hear the effect of changing the load on the dynamo by adding and removing bulbs - the whine increased with the load. It was good to see the ring oilers doing their job and not flinging oil out of the chambers which happened when I 'motored' the dynamo and it reached about 2000 rpm - covers for the oil chambers required.

I was impressed with the brightness of the bulbs, only after the test did I find I had been using six instead of twelve volt bulbs, no wonder they heated up so quickly.

The dynamo seems to be performing very well nothing gets warm - windings or bearings and I haven't seen any sparks from the copper braid brushes so I must tidy the model up finish the details and paint it. I also need to devise a suitable base for mounting the model, wood is probably the easiest.

Andy

 
Title: Re: Retlas "Manchester" Dynamo
Post by: Chipmaster on May 19, 2023, 09:36:23 PM
Pictures of the dynamo in its finished state. I should have posted these last year.

 (https://live.staticflickr.com/65535/51894932912_af8420b384_c.jpg) (https://flic.kr/p/2n4M6yC)IMG_E3762 (https://flic.kr/p/2n4M6yC) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

(https://live.staticflickr.com/65535/51896231119_ff452de416_c.jpg) (https://flic.kr/p/2n4TKtv)Clipboard01 (https://flic.kr/p/2n4TKtv) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

(https://live.staticflickr.com/65535/51894932947_3b4032a318_c.jpg) (https://flic.kr/p/2n4M6ze)Clipboard02 (https://flic.kr/p/2n4M6ze) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

(https://live.staticflickr.com/65535/51894932862_0458b227e7_c.jpg) (https://flic.kr/p/2n4M6xL)Clipboard04 (https://flic.kr/p/2n4M6xL) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr
Title: Re: Retlas "Manchester" Dynamo
Post by: Kim on May 19, 2023, 11:12:41 PM
That's beautiful!  I love the wood, brass, and black that you've used.  It looks great together like that!  :ThumbsUp: :popcorn:
 
Kim
Title: Re: Retlas "Manchester" Dynamo
Post by: Alyn Foundry on May 20, 2023, 01:04:21 PM
Many thanks for the pictures Andy.  :ThumbsUp:

It’s great to see the final results. How many have been “ fooled “ with regards to its age I wonder?

 :cheers:  Graham.
Title: Re: Retlas "Manchester" Dynamo
Post by: Roger B on May 21, 2023, 07:02:20 AM
Looks magnificent   :praise2:  :praise2:  :wine1:

Have you driven it with the engine yet?
Title: Re: Retlas "Manchester" Dynamo
Post by: SteamR on May 21, 2023, 07:26:35 PM
A nicely build dynamo and a masterpiece.
Congratulations

Richard
Title: Re: Retlas "Manchester" Dynamo
Post by: Chipmaster on May 22, 2023, 08:34:56 PM
Thanks Richard, Graham and Kim.
Hi Roger, I did drive it with my Retlas engine on just one occasion back in January 2021 and haven't used it since. I began making a large pulley to fit on the Retlas engine using a Mini 7 inch brake drum to speed up the dynamo but haven't got round to finishing the job. My how time flies, so many unfinished projects.
 
(https://live.staticflickr.com/65535/50888020783_e62d464ba1_c.jpg) (https://flic.kr/p/2kwNpEF)P1090600 (2) (https://flic.kr/p/2kwNpEF) by Andy (https://www.flickr.com/photos/116764188@N08/), on Flickr

Here's a YouTube video.
https://www.youtube.com/watch?v=FN4ARGutcls

Andy
SimplePortal 2.3.5 © 2008-2012, SimplePortal