By continuing to use this site, you agree to our use of cookies. Find out more
Forum sponsored by:
Forum sponsored by Allendale Jan 24th

The Post Man Cometh.

James Coombes Engine

All Topics | Latest Posts

Search for:  in Thread Title in  
Nigel McBurney 123/11/2014 22:44:47
avatar
779 forum posts
3 photos

To drill holes on a pcd, for example 6 or 8 holes in a cylinder cover,aquire a vertical indexing chuck with 24 positions, which provides most of the useful pitches ,and use it mounted on the vertical mill table.Its accurate and there is no backlash error or indexing of the mill table.

Nick_G23/11/2014 23:10:58
avatar
1808 forum posts
744 photos
Posted by Nigel McBurney 1 on 23/11/2014 22:44:47:

To drill holes on a pcd, for example 6 or 8 holes in a cylinder cover,aquire a vertical indexing chuck with 24 positions, which provides most of the useful pitches ,and use it mounted on the vertical mill table.Its accurate and there is no backlash error or indexing of the mill table.

Thanks for that. smiley

I did consider this option. But a 1/2 decent one would cost as much as a DRO setup. And a 'decent' one many times more.!

Cheers, Nick

Nick_G26/11/2014 21:57:14
avatar
1808 forum posts
744 photos

.

I am now 4 weeks into this my first build. - But sorry Jason still no PCD holes yet.! wink

Carved out the holes in the plates. Diverted from the drawing slightly as I want to give the engine a 'personal touch' with more rounded corners. (I will use that excuse later when I make a cock-up cheeky)

The hole is larger on the bottom plate than the drawing says due to me having an a-la Baldrick " cunning plan"

The bearings are drilled, tapped and fitted. Although they do need dressing. Nice snug fit but rotate nice and free with a dab of lubrication on the crankshaft.

While on that subject what is a good oil for running in.? (when the time comes)

.

I wonder the stage I will be at in another 4 weeks.? - Maybe even some PCD holes eh Jason.! laughsurprisecheeky

Nick

Martin Cottrell26/11/2014 22:06:51
297 forum posts
18 photos

Nick,

It looks to be coming along very nicely, a fine job by any standard let alone a first attempt! It looks like quite a big engine or is that just the perspective of your photo with the engine in the foreground, what diameter is the flywheel?

Regards Martin.

Nick_G26/11/2014 22:13:30
avatar
1808 forum posts
744 photos
Posted by Martin Cottrell on 26/11/2014 22:06:51:

what diameter is the flywheel?

Regards Martin.

 

 

Thanks for the nice remark Martin. Much external advice though. - It's a 7" dia flywheel.

Here is the spec on the Stuart site. :- **LINK**

 

Regards, Nick

 

Edited By Nick_G on 26/11/2014 22:16:33

JasonB27/11/2014 07:43:29
avatar
Moderator
19587 forum posts
2150 photos
1 articles

Nick looking at your marking out you could just mark, punch and drill the holes as you seem quite capable of accurate marking out. Any light oil will do but not steam oil.

J

lancelot05/12/2014 11:18:50
avatar
63 forum posts
4 photos

Hi Nick...how are you getting on with the Coombes ? I found that there were a few mechanical fouls on my build (possibly due to working with outdated and then the latest drawing)...

Keep her cuttin Nick...

John.

Nick_G05/12/2014 23:25:24
avatar
1808 forum posts
744 photos

.

Hi John,

OK-ish I think. Not done so much this week but I have made the eccentric strap.

I first sliced the casting and soldered it back together before placing it in the 4 jaw. I 'tinned' the 2 halves and used spring bulldog clips to hold it together in alignment. This snapped the parts together nicely when the solder remelted.

They came apart easily after the machining was done with little heat.

The remaining solder cleaned off.

.

The next thing I intend to make is the crankshaft eccentric and would like a little bit of advice please on the best way to go about it. The supplied stock is quite short in length but I do have a longer length already if it would make things simpler.

So guy's what is the best machining order to produce the eccentric part below :-

Many thanks, Nick

Mike Poole06/12/2014 01:58:13
avatar
Moderator
2849 forum posts
67 photos
Posted by Nick_G on 26/11/2014 21:57:14:

While on that subject what is a good oil for running in.? (when the time comes)

Graphogen is good for motorcycle engine rebuilds, applied as an assembly compound. Their website recommends its use for all fine machinery.

Mike

Nick_G06/12/2014 10:39:53
avatar
1808 forum posts
744 photos
Posted by Michael Poole on 06/12/2014 01:58:13:

Graphogen is good for motorcycle engine rebuilds, applied as an assembly compound. Their website recommends its use for all fine machinery.

Mike

Thanks Mike.

Nick

Neil Wyatt06/12/2014 12:22:56
avatar
Moderator
18416 forum posts
718 photos
78 articles

I use good ol' 3-in-1 for running it, largely as its pretty clean and innocuous when you get it on your fingers, clothes etc... and also because a spouted can makes it easy to get into small spaces (although we all ought to be making Mogen Kilde's oilcan!

Neil

NJH06/12/2014 14:18:15
avatar
2314 forum posts
139 photos

Nick

Chuck the stock, face off, then use the strap you have just made as a gauge for turning the outside dia. of the sheave to fit ( don't forget 1 1/8" first to fit the recess in the strap then 1 1/16" for the rest - easy to get it the wrong way round and produce a "scrapper!) . It's best to leave the 1 1/8" a little large at first and concentrate on getting the fit on the 1 1/16" good. Easy to take a bit more off the ridge later to get a good fit. Face off then remove from the lathe and, from the centre ( which will be apparent from the turning marks), scribe a line 9/64" below the centre and centre pop. Put back in the 4-jaw and adjust so that the centre mark runs true. Centre drill, drill and ream 7/16" then reduce the O/D of the boss to 11/16" dia. Lastly remove from the lathe and cross drill and tap for the grub screw.

It worked for me- I've not made this one but I did make the "Real" , which uses the same parts, years ago.

 

Good luck!

Norman

Edited By NJH on 06/12/2014 14:24:21

Ian S C07/12/2014 10:28:35
avatar
7468 forum posts
230 photos

From what I can find 3in 1 oil is similar in make up to WD-40, a better oil is sewing machine oil.

Ian S C

Neil Wyatt07/12/2014 11:54:36
avatar
Moderator
18416 forum posts
718 photos
78 articles

> 3in 1 oil is similar in make up to WD-40

They are utterly different! 3 in 1 is spindle oil so excellent for lubrication, while WD40 is a penetrating and water displacing product.

Neil

JasonB07/12/2014 13:20:10
avatar
Moderator
19587 forum posts
2150 photos
1 articles

The other two parts of the 3 in 1 oil are not really needed eg anti rusting and cleaning properties, so teh sewing machine oil that is all oil is a better choice for small parts.  I just use a light machine oil, the same as goes into my lathe gearboxs

Edited By JasonB on 07/12/2014 13:21:16

Neil Wyatt07/12/2014 15:04:21
avatar
Moderator
18416 forum posts
718 photos
78 articles

I don't think they do any harm, and are probably beneficial in terms of getting a film of oil on the bright parts of models and tools.

It's nothing to do with me growing up on a diet supplemented by 3 in 1

Neil.

Nick_G12/12/2014 10:21:20
avatar
1808 forum posts
744 photos

.

I managed to make a right 'dogs danglers' of the eccentric on my first effort. blush

So with some new steel I had another dabble with lessons learned and a clearer mind.

.

Think I will go over to the valve chest next during the weekend. yes

And especially for Jason perhaps even some PCD holes. wink

Nick

Roger Williams 212/12/2014 11:42:37
331 forum posts
1 photos

Nick G, lovely work and photos. For doing your PCD's, have you considered making a simple dividing head like this one , that uses changewheels. I made this one years ago for my Myford (regrettably sold recently !), so made a raising block for this lathe. It bolts on either way in a couple of minutes, so handy. Has a 48T changewheel on at the minute. Cheers.dscf1016.jpg

Nick_G12/12/2014 11:45:48
avatar
1808 forum posts
744 photos

.

Hardinge lathe.!!!! ......................................... Drooooooooooool.!!!! smile psmiley

Thanks for the tip.

Regards, Nick

Nick_G14/12/2014 20:02:07
avatar
1808 forum posts
744 photos

.

Valve chest has been today.

I faced off the sides in the 4 jaw on the lathe both the chest and it's cover.

Then into the 3 jaw to drill for the valve rod. There is a slight offset on to one side for this.!

A long series drill was needed to drill the valve rod guide pocket.

Advice was sought and excellently given to me on another thread about the use of super glue to keep the parts in the correct position for drilling the studs.

The tapping dia was run through the cover, valve chest and cylinder castings.

The guide holes were then opened out in the chest and cover.

This worked out very well so thanks for the super glue tip and to all the others who have assisted me thus far.! laugh

 

Nick

Edited By Nick_G on 14/12/2014 20:03:30

All Topics | Latest Posts

Please login to post a reply.

Magazine Locator

Want the latest issue of Model Engineer or Model Engineers' Workshop? Use our magazine locator links to find your nearest stockist!

Find Model Engineer & Model Engineers' Workshop

Latest Forum Posts
Support Our Partners
emcomachinetools
ChesterUK
EngineDIY
cowells
Warco
Eccentric July 5 2018
Eccentric Engineering
Subscription Offer

Latest "For Sale" Ads
Latest "Wanted" Ads
Get In Touch!

Do you want to contact the Model Engineer and Model Engineers' Workshop team?

You can contact us by phone, mail or email about the magazines including becoming a contributor, submitting reader's letters or making queries about articles. You can also get in touch about this website, advertising or other general issues.

Click THIS LINK for full contact details.

For subscription issues please see THIS LINK.

Digital Back Issues

Social Media online

'Like' us on Facebook
Follow us on Facebook

Follow us on Twitter
 Twitter Logo

Pin us on Pinterest