Doxford opposed piston engine model

[bytewise]

As mentioned in my intro. I am building a 1/10 scale model of a Doxford opposed piston diesel engine. The engine I am modeling was a single cylinder prototype built in 1914.
My source of information was the web site www.oldengine.org/members/diesel/marine/doxford.htm and pictures of the Doxford factory and engines. There are a number of posts on the web about the Doxford company and engines.
I am using the TurboCad prgram and have made over a hundred drawings for the project. I had to design the details from fairly crude source information.
I have made a few test pieces of some critical gears in the cam shaft drive. These are both 1:1 ratio. Pics attached.
I am now ready to get materials and start making chips. I have made a couple of patterns and am negotiating with a casting company to cast them. This is my first attempt to make patterns for casting. I will post progress and pictures from time to time.
Hugh

[Don1966]

Those are some nice looking gears Hugh. How do you go about making the spiral cut in them? I have never made any like that. I will be tagging along with you, this should be a very interesting build.

Don

[b.lindsey]

Quite an interesting and challenging project. Have you found other that the cross section drawings to scale from? While they are good, that would still be a difficult task I would think with lots of room for interpretation.

Bill

[Dan Rowe]

This will be very interesting. I worked on both Sulzer and B & W marine diesels as a ships engineer. I never had a chance to sail with a Doxford but It would have been fun.

Dan

[bytewise]

Cutting helical gears requires a universal horizontal mill and dividing head. The table is turned to the helix angle and the dividing head is geared to the table feed screw. The first three pictures show the setup for a gear of 45 deg. helix angle.
One of the gears I needed had to have a helix angle of 63 deg. The mill will only go to 45 deg. So, I used a rather tricky setup using a vertical milling head on the horizontal machine. The last two pictures show the setup. Thee table angle was at 0 deg. The vert. head was set to put the cutter at 63 deg. The div. head was geared to the table to get the proper helical lead. The mating small gear cutting used the conventional setup with a helix angle of 27 deg. The helix angles of the gears must add up to 90 deg.

Re: sources of info. The pictures of the Doxford shops showed me the shape and proportions of the parts. I had to use my imagination and design the details for myself. I have been working on the drawings for about a year and have about 120 done. I am now starting to get materials and start cutting.
Hugh

[ths]

Hi Hugh,

Exciting stuff! Great machinery and really interesting setups. Those photos have finally caused the universal milling penny to drop for me. I look forward to seeing more of what seems to be a fairly major project.

Cheers, Hugh. (no, not a self congratulatory post!).

[steamer]

Nice Hugh!   You don't see that set up too often!

Dave

[Don1966]

Hugh, thanks for the excellent photos and explanation of how the gears were done. I look forward to more of your progress.

Don

[smfr]

Wow, that's quite the setup. Will be watching this one with interest!

Simon

[DennisWA]

Hugh...This looks to be a most interesting and challenging project! What make is your milling machine - is it the Becker mentioned in your intro post?

For those interested there is a lot on Doxfords on http://users.telenet.be/doxford-matters/
and the pictures of the machining and assembly at the Doxford works in Sunderland are fascinating http://users.telenet.be/doxford-matters/#index.

Dennis

[bytewise]

Dennis: The mill used for making the gears is a B&S Uni. Horiz. #2 from about 1914. The div. head is also B&S and fits the mill exactly. I did have to make the set of gears for differential and spiral milling. With gears in addition to the code plates, you can cut ANY NUMBER of teeth up to 350.
Thanks to all for the encouraging comments.
Hugh

[DennisWA]

Hugh:  Thanks for clarifying the mill used.

I saw your intro post and misread the "B&S univ. horiz. mill and dividing head(1913)" as being the dividing head only!

Have you had any contact with Alfons Verheijden http://users.telenet.be/doxford-matters/? He seems to have a lot of enthusiasm for Doxfords and has posted on the Ships Nostalgia website as well.

Cheers
Dennis

[bytewise]

Dennis: Yes. He had several posts of useful detail information. There are quite a few posts about the Doxford company and their engines.
Hugh

[Dan Rowe]

Hugh you might already know this but there is a page about this engine in "Diesel's Engines" by Lyle Cummins. There is a close up of the operating controls that has arrows pointing to the various devices. The photo of this engine was used as ad copy in the 1920's. Here one of the ad pages:
http://www.flickr.com/photos/averheijden/2310134743/in/pool-doxford/

Here is the brief description of the engine from page 592 of the book:

   "The prototype closely followed the functional features of a Junkers single-opposed
design. The bore was 500 mm and the stroke of each piston was 750 mm. With an out-
put of 500 bhp and 190 rpm the bmep was high, for a 2-stroke, of 90 psi. During a five
week test under Lloyd's supervision the engine was stopped for minor repairs only five
times, and the output never fell below 470 bhp. Fuel consumption using a Mexican oil
with a .91 sp gr. never went above 0.43 lb/bhp/hr. The engine ran at speeds as low as 35
rpm with no misfiring.¹²¹"

The chapter reference is "The Doxford Opposed-piston Marine Oil Engine", The Motor Ship and Motor Boat June 3, 1915, p. 17 of Doxford reprint.

Dan

[bytewise]

Yes, the photo in the 1920 ad. is the engine I am modeling.
Status: My patterns were accepted by the foundry and will be cast next week. These are a flywheel and end plates for the crankcase. I will post pictures when I get them.
Hugh