Model Engine Maker

Help! => Specific Engine Help => Topic started by: kellswaterri on June 09, 2015, 10:53:20 PM

Title: james coombes.
Post by: kellswaterri on June 09, 2015, 10:53:20 PM
Hi  folks...back  in the shed and finally have the Coombes finished...the little compressor unit is  basically only for tyres or air beds and has not   the power to turn over the  engine,   although it did give a few kick overs about half a rev...a few questions if I may ask...what pressure will i need to turn it fast enough ...   2nd  &  3rd  questions are related to the drawings...I started the build with the original first drawings...then a long break of a few years...when I got back in the shed the first drawing had faded with the sun new drawing had some valve gear linkage problems....so current situation ...not enough air pressure   (run on steam)???...valve gear dimensions ...or possibly the occillator dimensions ...please can any one supply those dimensions from an engine which has been running...Cant be all that wrong if it tries to start???
                                                              all the best for now,
                                                                            John...lancelot.
Title: Re: james coombes.
Post by: Jo on June 10, 2015, 08:07:26 AM
 :pics:

We don't accept excuses  ;)

Sorry I don't have a copy of the Coombes drawings  :disappointed:

Jo
Title: Re: james coombes.
Post by: Ian S C on June 10, 2015, 01:03:28 PM
Sounds as though you just need a compressor with a bit more capacity,  I found that the Stuart Turner S9 would just give a bit of a kick when hooked up to the 12v car tire compressor.  My home made workshop comperssor had a job keeping up with the volume of air required, it only needed 10/20psi, just quite a bit of it.  The James Coombs should only need about that pressure, maybe a fraction more until it frees up.
Ian S C
Title: Re: james coombes.
Post by: kellswaterri on June 10, 2015, 03:21:32 PM
Hi Jo and Ian...thank you for the speedy reply...I ran it on steam this after noon ...not a blooming twitch!!!It turns over quite freely I am beginning to believe that the throw dimension for the valve gear con rod is wrong and the steam valve is not getting enough movement in either direction...
a little bit of further work still...
                             John.                                                                                                                                                                                                                                                                                                   
Title: Re: james coombes.
Post by: kellswaterri on June 13, 2015, 07:14:52 PM
hi folks...on further checking I got loan of larger compressor...made up a set of fittings for inlet.... checked for linkage looseness to valve gear applied pressure...the flywheel whipped round about just over 1/2 way...no amount of fiddle with eccentric sheave helped ...the problem I am fairly certain is the throw dimension in the new drawing I am working to supplements all previous ones including the build book ...(giving   11/64'')...THE NEW DRAWING HAS IT AT 9/64''   which is what I made the part to...I can now see that 11/64 '' is the more likely measurement  so I will have to make a new one ...could anyone confirm 11/64''as the right dimension...
                                                         this would be most appreciated...
                                                                           John.
                                    Sorry  Jo   the photo machine is not playing fair at moment will keep trying...
Title: Re: james coombes.
Post by: smfr on June 13, 2015, 09:54:04 PM
My 1977 plans for the James Coombes show the eccentric throw as 9/64". I haven't built it yet, so I can't verify that this is correct!

But if you throw is wrong, it should just affect the valve travel. Is the valve fouling the inside of the valve chest, or is there interference on the outside? A bit of inspection while turning it over by hand should tell you why it's not running.

Simon
Title: Re: james coombes.
Post by: kellswaterri on June 14, 2015, 08:33:37 PM
Hi Simon...my drawing is 1993 issue and still gives 9/64'' as throw... the valve s are ported in the cylinder already when kit was supplied  inlet valves   3/32''   with 3/8'' between top and bottom...the exhaust port is 3/16''   (careful...right on centre line of centre two stud holes for the valve chest...
                       LOVELY......cheers...John.
Title: Re: james coombes.
Post by: AOG on June 14, 2015, 11:14:46 PM
Hi Simon...my drawing is 1993 issue and still gives 9/64'' as throw... the valve s are ported in the cylinder already when kit was supplied  inlet valves   3/32''   with 3/8'' between top and bottom...the exhaust port is 3/16''   (careful...right on centre line of centre two stud holes for the valve chest...
                       LOVELY......cheers...John.

have you checked that there is no moulding sand in the passage ways? Pull the end covers off and try to blow air into the ports and see if you can feel it come out the cylinder. If not the ports are probably blocked with sand. Get a piece of wire and clean them out.

Tony
Title: Re: james coombes.
Post by: smfr on June 15, 2015, 12:27:55 AM
Hi Simon...my drawing is 1993 issue and still gives 9/64'' as throw... the valves are ported in the cylinder already when kit was supplied  inlet valves   3/32''   with 3/8'' between top and bottom...the exhaust port is 3/16''   (careful...right on centre line of centre two stud holes for the valve chest...

Those dimensions agrees my my plans too. Any luck?

Simon
Title: Re: james coombes.
Post by: kellswaterri on June 15, 2015, 10:43:57 AM
Hi Folks...just off  the phone to Stuarts ...picking their brains  ...after checking what was done and my description of how the engine reacted to pressure    he said it should work just fine on 9/64''.....but he thought same as you Tony      sand possibly partly ckocking the port passages.
back soon...with good news I hope...John.
Title: Re: james coombes.
Post by: Jo on June 15, 2015, 10:52:52 AM
back soon...with good news I hope...John.

AND PHOTOs  ;)

Jo
Title: Re: james coombes.
Post by: Stuart on June 15, 2015, 12:44:20 PM
John

If you are a win doze user ( I am not )

This site will help with the valve gear dims

First lot are DOS. But the windoze  :toilet_claw: files are lower down

They will show with reversing ,but put in the dims and see if it will work try both sets and look at the difference

Stuart
Title: Re: james coombes.
Post by: kellswaterri on June 17, 2015, 12:03:12 PM
not possibly the correct thing to do ...having some difficulty ...latest photo  to go.....

C:\Users\John\New folder (2)ME ONLY\2015-05-17\Phone\DCIM\Camera\20150426_170825_2.jpg
Title: Re: james coombes.
Post by: Jo on June 17, 2015, 01:05:58 PM
John you need to insert that link into the add attachment box below the box where you type in your messages before posting. The we will be able to see the Photo  ;D

Jo
Title: Re: james coombes.
Post by: kellswaterri on June 17, 2015, 02:19:27 PM
trying this''......head sore now ...think I will go and lie down...... :noidea:
Title: Re: james coombes.
Post by: Jo on June 17, 2015, 02:32:26 PM
 :whoohoo:

Looking all nicely engine shaped  8).

Now that you have worked out how to do it  :naughty: Could we have a couple of others  :-X  ;D

Jo
Title: Re: james coombes.
Post by: kellswaterri on June 17, 2015, 02:52:53 PM
 :old: :headscratch: :noidea: :embarassed: :Mad: :cussing: ;)
Title: Re: james coombes.
Post by: Jo on June 17, 2015, 04:15:10 PM
 :facepalm: I do that: link to the same photo twice  :old:

Do you have any.. different photos of it ;)

Edit: that's better you can see the whole engine  8)

Jo
Title: Re: james coombes.
Post by: kellswaterri on June 17, 2015, 08:43:55 PM
some more as i can catch them......
Title: Re: james coombes.
Post by: kellswaterri on July 22, 2015, 09:40:59 PM
Hi folks,...i have put the Coombes to bed for a while and have cleared the decks to do some work on building the corliss......milled one of the bed plates to size after marking out the points to mill to...a lot of working out the dimenions ...definetly not a stuart and turner jobby...went to one of our local Dentists and Scrounged about a dozen tiny little Tungsten ( i think ) ball ended rotary burrs ...they are perfect for spotting or starting holes in awkard positions I used the Cowells mill with a cutter normally used for cutting Carbon fibre ...like a knife through butter the set  up for the slide bed will be some what tricky  I think,
                                      Cheers ,
                                                John.
Title: Re: james coombes.
Post by: Jo on July 23, 2015, 07:27:48 AM
John are you going to start a seperate thread about your Corliss engine?

You might even convince me to get on with building my  :o huge one .

Jo
Title: Re: james coombes.
Post by: kellswaterri on July 23, 2015, 08:57:58 AM
I will more than likely do just that...invested in a descent calculator and a couple of (crap,o cad)  Pukka pads one pocket sized...I have a brand new Bosch industrial l electronic \router, which i am going to make a rig to allow for more  milling ops ...will see how that works...currentlu browsing fora build sequence ...if I can find one.

                                                                                                       cheers,
                                                                                                                    John.
Title: Re: james coombes.
Post by: b.lindsey on July 24, 2015, 12:32:47 AM
Another Corliss....will be looking forward to that!!

Bill
Title: Re: james coombes.
Post by: kellswaterri on July 25, 2015, 11:27:57 AM
Putting the Coombes to bed for a while  ......Over to the Corliss build,
                 Good night folks.
                      Kellswaterri.
Title: Re: james coombes.
Post by: kellswaterri on September 15, 2015, 06:45:56 PM
Hi folks...back in shop again..Corliss cylinder on hold while i make a parellell long grinding tool from a tapered stone !!!I am going to try grinding out the hard spot'''anaway ,
now back on the ''James Coombes''...had to make a new ocillator sheave out of bronze...and make good fit to the big end.  some minor faffing about and then I gave itfull power from my new compressor...AMAZING!!!the reluctant sod actually works ...I ran it while yelling at top pitch for a photo or videoAll cloth eared ?***!!It eventually slowed down and stopped ...I found that the slotted  grub screw was notholding the sheave  so need to obtain someallen type grubs...
 The bit that I am happiest with is that my design changes work...
                                                 All the best for now...
                                                              John.
Title: Re: james coombes.
Post by: Admiral_dk on September 15, 2015, 08:20:08 PM
Great - looking forward to the video.
Title: Re: james coombes.
Post by: kellswaterri on September 16, 2015, 03:44:33 PM
Hi folks...I have just made a video of the engine running...I hope that I can show it here...

firstly not having posted a video to a forum , how do I go about doing so
                                                                  John    (kellswaterri)
Title: Re: james coombes.
Post by: Jo on September 16, 2015, 03:49:02 PM
Hi John,

A runner  8)

You need to host the video on something like Utube and then provide a link to the address (URL) in a post here if you look above the smilies there is a button which adds the characters to the address to make it work on the forum.

Jo
Title: Re: james coombes.
Post by: kellswaterri on September 16, 2015, 05:26:27 PM
_bvYfiyr9jc[/youtube1]

Hi folks ...as I have not tried this before ...Here's good luck...
                                                   Kellswaterri.
Title: Re: james coombes.
Post by: Jo on September 16, 2015, 05:33:11 PM
 :whoohoo:  A runner  ;D

I see you find focusing the camera as challenging as I do  ::) Is there an automatic focus setting I find using that helps no end.

Jo
Title: Re: james coombes.
Post by: Roger B on September 16, 2015, 06:11:58 PM
Well done  :praise2: A runner is always good  :ThumbsUp:  :ThumbsUp:
Title: Re: james coombes.
Post by: kellswaterri on September 16, 2015, 09:53:01 PM
Yes Jo,  it is both auto and manual focus ...i had  it set on manual with out checking ,it was mounted on a tripod behind me and i had to use a mirror to see what was on the screen,then switched over to auto ...U tube did a pretty good  job of tidying up my efforts ,...thanks U TUBE...i have just ordered some grub screws in BA  sizes...and am realizing that  BA material is almost a bad word to traders ...I could obtain a box of 200 easily enough 30 of them ...different story same with silver steel rod ...It is rather costly investing in new metric tooling.
                           cheers,
                                      John.   (Kellswaterri)
Title: Re: james coombes.
Post by: kellswaterri on September 21, 2015, 03:36:54 PM
S.O.S.####
                 Spent about 3 hours on the net , trying to obtain   NO 5BA...grub screws steel   allan key type could anyone tell me of a stockist or spare me a couple,,,the occilator sheave keeps slipping as those ruddy slotted ones are not up to holding. :Mad:
all the best ,
                  Kellswaterri   John.


Title: Re: james coombes.
Post by: Jasonb on September 21, 2015, 03:43:37 PM
http://www.ba-bolts.co.uk/grubs.html
Title: Re: james coombes.
Post by: kellswaterri on September 25, 2015, 10:53:43 PM
Hi Jasonb...just obtained some no 4   and no 5   grubs                                                                                                                                                 
          cheers,
                        John.