James Coombes Engine
Nigel McBurney 1 | 23/11/2014 22:44:47 |
![]() 1101 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_G | 23/11/2014 23:10:58 |
![]() 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. 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_G | 26/11/2014 21:57:14 |
![]() 1808 forum posts 744 photos | . I am now 4 weeks into this my first build. - But sorry Jason still no PCD holes yet.! 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 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.!
Nick |
Martin Cottrell | 26/11/2014 22:06:51 |
297 forum posts 18 photos | Nick,
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Nick_G | 26/11/2014 22:13:30 |
![]() 1808 forum posts 744 photos | Posted by Martin Cottrell on 26/11/2014 22:06:51:
what diameter is the flywheel?
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 |
JasonB | 27/11/2014 07:43:29 |
![]() 25215 forum posts 3105 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 |
lancelot | 05/12/2014 11:18:50 |
![]() 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_G | 05/12/2014 23:25:24 |
![]() 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
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Mike Poole | 06/12/2014 01:58:13 |
![]() 3676 forum posts 82 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_G | 06/12/2014 10:39:53 |
![]() 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 Wyatt | 06/12/2014 12:22:56 |
![]() 19226 forum posts 749 photos 86 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 |
NJH | 06/12/2014 14:18:15 |
![]() 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 C | 07/12/2014 10:28:35 |
![]() 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 Wyatt | 07/12/2014 11:54:36 |
![]() 19226 forum posts 749 photos 86 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 |
JasonB | 07/12/2014 13:20:10 |
![]() 25215 forum posts 3105 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 Wyatt | 07/12/2014 15:04:21 |
![]() 19226 forum posts 749 photos 86 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_G | 12/12/2014 10:21:20 |
![]() 1808 forum posts 744 photos | . I managed to make a right 'dogs danglers' of the eccentric on my first effort. 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. And especially for Jason perhaps even some PCD holes.
Nick |
Roger Williams 2 | 12/12/2014 11:42:37 |
368 forum posts 7 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. |
Nick_G | 12/12/2014 11:45:48 |
![]() 1808 forum posts 744 photos | . Hardinge lathe.!!!! ......................................... Drooooooooooool.!!!! Thanks for the tip.
Regards, Nick |
Nick_G | 14/12/2014 20:02:07 |
![]() 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.!
Nick Edited By Nick_G on 14/12/2014 20:03:30 |
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