| The Shop > Metal Stuff |
| Slowly casting up parts for a steam twin marine engine |
| << < (15/27) > >> |
| Artie:
Hi all, the eccentrics are finished and pictured here mounted on a piece of the rod to be used for the crank. Some finishing required to remove fine burs and smooth/polish it all out. A 4mm grub screw locks them to the shaft. I had to make a new tap holder for the tapping tool as this size tap had a larger shaft than the first 4BA tap (see here http://madmodder.net/index.php?topic=2929.0). I didnt take pics but the first eccentric took 45 mins (make tool etc) and the rest took only 10 mins each to finish. This entailed, mill flat, change tool for drill, then change again for tap pilot. This ensured that the alignment didnt alter. So I had to do this whole process 4 times. This required setting the eccentric to its required orientation, mill a small flat at 4mm, then drill to 3.2mm and the tap in the holder to 4mm by 0.75mm pitch. I am making the crank in two parts with a joiner in the centre. This was decided when I wasnt sure whether to use the water pump which Edgar T describes as possibly necessary for his design. This requires an eccentric sheave much the same as those for the valve gear mounted at the centre of the crank. If my crank is one piece it must be added now. If two piece I can add it later if necessary. Therefore I need a joiner. I am also making the shaft that mounts the paddle wheels as as seperate units and these will run on bearing blocks mounted in the hull. These joiners will allow shock reduction (not necessary) but more importantly are flexible and will allow misalignment if I happen to build some in unwittingly. You can see how these will look once done. These will be mounted to a one piece shaft as seen here, some release agent will be used to coat the shaft and then RTV silicone injected into the gaps and smoothed out. Once set this will supply a flexible one piece joiner. I had the RT mounted on the mill and the 4 jaw on it. A shaft is centred in this and the aluminium blanks are tapped with grub screws and mounted on this shaft. A 3mm end mill used to machine most of the material away to leave 4 'blades' which fit into corresponding blades on the mating piece. I was going to be moving onto the rods which mount on the sheaves (eccentrics) but decided to stray... hence the joiners today. Until next time... cheers all.... Robt T |
| Artie:
I finished the flexible couplings last night and a couple of pics to show how they turned out.... I used wax as a release agent and alos cleaned everything with brake cleaning chemicals. Stuff is aggressive as hell but removes all oils and greases. Then positioned everything ont he shafts and lightly nipped up the retaining screws, injected the rtv silicon and smothed over with a wet finger.. the crank webs make great holding jigs... And now set.. will leave in shaft for a few days to ensure its as strong as possible. |
| Stilldrillin:
Really enjoying this build Rob. :thumbup: Love your flexi couplings. Well done! :clap: David D |
| Artie:
Thanks Dave, Im really happy with the result.... and I should mention that I machined the aluminium rod up from a piece I had cast up some tiem ago. No pin holes nice and smooth to machine... this is that 6061 that I got as scrap fire extinguishers..... truly rolling my own..... :) I got the idea from the rear wheel of my Ducati when taking it off to change a tyre... cush drive? ..... mmmm....... Tonight I had a play with the crankshaft... remember this will have one of these couplings in the centre as well so this is assembled way too wide and Ill cut it down to suit when Im ready to do so.... Progress..... This is lightly pressed together, not enough to ensure it wont move though, so ...... do I drill tap and fit grub screws (leaning that way, makes it dismantleable for whatever reason)? Or do I silver solder? If I solder Im going to have to relieve the fit so the solder can penetrate.... I am after advice here folks.... thanks in advance..... Cheers Rob T |
| Artie:
A brief pic...just to prove that the wax worked as a release agent.... as I had hoped.... relieved..... these seem strong and quite flexible.. Ive pulled bent twisted them.... Ive have started to think that they may well work... never in doubt..... Next couple of weeks are they travel/work cycle... Ill be quiet for a while..... until I get back... Cheers Rt |
| Navigation |
| Message Index |
| Next page |
| Previous page |