jeff2wings Posted February 26 Author Share Posted February 26 Found time to make inlet and transfer covers would have preferred to make the inlet out of brass but didn't have any in the right size Quote Link to comment Share on other sites More sharing options...
Andy Stephenson Posted February 27 Share Posted February 27 I noticed, the last time I took a diesel engine apart, which was an PAW.55, that the transfer ports were machined into the bore of the cylinder rather than on the outside. Is this common practice with small engines or is this exclusive to PAW engines. Quote Link to comment Share on other sites More sharing options...
Paul De Tourtoulon Posted February 27 Share Posted February 27 No local boatyards where you could pick up a bit of brass from an old prop shaft ?. Quote Link to comment Share on other sites More sharing options...
jeff2wings Posted February 27 Author Share Posted February 27 'Modern ' diesel engines, as in '50's onwards used this method for the transfer ports probably as it makes the production of the casing easier. Quote Link to comment Share on other sites More sharing options...
911hillclimber Posted February 27 Share Posted February 27 What were the differences in the Sparey port dimensions please? Made mine to the supplied 2010 drg (+/- half a house brick) and getting ready to solder the port covers. Would like to know the difference incase I need to 'adjust' the position(s). Graham. Quote Link to comment Share on other sites More sharing options...
jeff2wings Posted February 27 Author Share Posted February 27 Original drawings show transfer and exhaust at 21/32 to the centre of the port,Hemingway drawings measure to the bottom of the port, and inlet at 13/32 to centre Quote Link to comment Share on other sites More sharing options...
911hillclimber Posted February 27 Share Posted February 27 Thank you. My drgs show the exhaust and the transfer @ 21/32 to their centres and the inlet 13/32 to it's centre from the same base surface/datum. I therefore think this is as per the original design? Quote Link to comment Share on other sites More sharing options...
jeff2wings Posted February 27 Author Share Posted February 27 Hemingway drawings Aeromodeller 46-47 And the book they came from Quote Link to comment Share on other sites More sharing options...
911hillclimber Posted February 27 Share Posted February 27 Phew! The dimensions on my drgs are the same as the original drg. Hemmingways have changed them at some recent time I presume. Quote Link to comment Share on other sites More sharing options...
jeff2wings Posted February 29 Author Share Posted February 29 Had a free afternoon so spent the afternoon on the lathe, basically bringing the o/d to final size and parting off to length and then deciding that the thread form wasn't exactly too my liking and taking another cut. also found the offcut of brass I was looking for so made another intake Next I will need to lap the cylinder and size the piston and c/p to size after soldering the intake and transfer on cylinder for second engine boring to size and as I need to make another crankshaft for the Speary, may as well make a couple for the Westbury atoms 2 Quote Link to comment Share on other sites More sharing options...
jeff2wings Posted March 1 Author Share Posted March 1 Made some useful progress today, hopefully will have it completed tomorrow Quote Link to comment Share on other sites More sharing options...
brokenenglish Posted March 1 Share Posted March 1 Shame the photo cuts off the top of your Owat. Quote Link to comment Share on other sites More sharing options...
911hillclimber Posted March 1 Share Posted March 1 About to start the crank on my Sparey also. Will be very interested to see your method to machine the crank pin, but I think that is what the above set-up is for? Quote Link to comment Share on other sites More sharing options...
jeff2wings Posted March 2 Author Share Posted March 2 It's based on a design from Hemingway ,your best bet is to machine between centers unless you have a piece of 2" aluminium bar stock to make an offset fixture Quote Link to comment Share on other sites More sharing options...
jeff2wings Posted March 2 Author Share Posted March 2 All sorted and ready to start making crankshafts! Quote Link to comment Share on other sites More sharing options...
911hillclimber Posted March 2 Share Posted March 2 Started my crank/crank pin turning this afternoon. Your Vee block gave me the inspiration, and it has worked well, albeit nowhere near the elegance, but I'm working with limited facilities (my best excuse). 2 Quote Link to comment Share on other sites More sharing options...
jeff2wings Posted March 3 Author Share Posted March 3 In total it took me 9 hours to make but the ease of setting up and surcurity of holding the crankshaft more than make up the expenditure of time. One of three to be made for Westbury Atoms Minors 1 Quote Link to comment Share on other sites More sharing options...
911hillclimber Posted March 3 Share Posted March 3 (edited) Started my crank/crank pin turning this afternoon. Your Vee block gave me the inspiration, and it has worked well, albeit nowhere near the elegance, but I'm working with limited facilities (my best excuse). Can I ask Jeff how you get such good surface finishes? Seems you use HSS tools, not replaceable carbide tips, is that the secret/ I'm struggling to keep the tips good machining the En8. Edited March 3 by 911hillclimber Quote Link to comment Share on other sites More sharing options...
jeff2wings Posted March 3 Author Share Posted March 3 Speed,feed and depth of cut,l'm running 200 rpm 20 thou cuts and hand fed face cut,I prefer hss as it seems more tolerant of interrupted cuts and of course you can regrind/shape them too suit,btw when you put a cut on how do you measure it as there are no graduations on your cross slide ? are you using a dial indicator? Quote Link to comment Share on other sites More sharing options...
911hillclimber Posted March 4 Share Posted March 4 Found the Hemmingway design on the web page, nice approach. The cuts I use are by instinct, 1/4 turn to 1/2 turn seems to be about 10 thou and I can cut 2 to 3 " in about 10 to 15 seconds all by hand turning the center screw on the round bed. I have a dodgy digital caliper to use to see how i'm progressing and down to the final pass. All a bit by touch and sound! Oddly, there is a graduated dial under the cross slide to set the angle od a taper cut, but you need a torch to read it. That is the only graduated control. Quote Link to comment Share on other sites More sharing options...
jeff2wings Posted March 11 Author Share Posted March 11 Having finished making the six crankshaft blanks made a bit more progress with the Speary 2,0 2 Quote Link to comment Share on other sites More sharing options...
jeff2wings Posted March 12 Author Share Posted March 12 Intake tube done and exhaust ports opened out, once I've made the N/V it's onto the piston/liner that's the hardest and most important part of the build Quote Link to comment Share on other sites More sharing options...
KEITH BEAUMONT 1 Posted March 13 Share Posted March 13 Jeff, When you say you are making Sparey 2,0, Doyou mean the 0.63cc Diesel? It certainly looks like it,but I am puzzeld by the apparent two piece crankcase? Presumably you have put another layer on so that you can machine the front transfer,rather than solder on a cover? Keith. Quote Link to comment Share on other sites More sharing options...
jeff2wings Posted March 13 Author Share Posted March 13 No,that would be this anonymous lump from Woking precision models (?) The following pictures should help explain, basically it's based on the Swiss Dyno construction 1 Quote Link to comment Share on other sites More sharing options...
jeff2wings Posted March 22 Author Share Posted March 22 A cNot had a great deal of spare time but have made a bit of progress on the second Speary although I needed to do some reworking in order to correct a mistake I made and one made previously by the guy that I bought the casting sets from. so wot happened was,I screwed the rear cover in and it got stuck, like proper stuck so I had to machine the hole thing out and then repair the damaged threads and the previous mistake by welding Once squared up I cut the recess and then brought it out to size and re-cut the thread ,then too take an actual step forward, soldered the intake and transfer on also found time to fixthe broken and missing timer arm on the Ok super 60 1 Quote Link to comment Share on other sites More sharing options...
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