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  1. Ramon

    Nalon Viper 2.5cc CI Engine

    Excellent link Ken, I do climb mill to eliminate burs but it does look like I've been doing it wrong for too long🙄 Not quite so sure that would be the answer on thin workpieces but for blocks that really looks worth a try. 👍 Tug
  2. Ramon

    Nalon Viper 2.5cc CI Engine

    This might be of use to others Pat so repeating it here. Hi Pat - just come in for a coffee! Make the ring first, say .5 mm larger than the housing and about 2mm wall thickness, face one end square to the bore and chamfer the outer diameter. Set the part on the mandrel and bore until the ring...
  3. Ramon

    Nalon Viper 2.5cc CI Engine

    Morning Patrick, now off for a day in the garden for a change but before I go ........ The mandrel wants to fit the rear bearing housing as a plug gauge would - the front portion of the gauge is the part that does the gripping - a 2 BA/4mm cap head would be fine for the expanding screw. The...
  4. Ramon

    Nalon Viper 2.5cc CI Engine

    Well it's not as bad as you might think Patrick and yes you can learn from it - not only the mistake but how to rectify it. Fit the front bearing and try the shaft and rear bearing - if theres any form of misalignment don't force it just remove the bearings. Turn a ring of ally say .5mm bigger...
  5. Ramon

    Nalon Viper 2.5cc CI Engine

    Good progress Patrick but if you get the front and rear bearing in line concentrically and parallel with each other on a four jaw set up you will be a lucky. I'm not saying it can't be done but there is no way of knowing exactly where the rear housing is in a four jaw set up. For the tolerances...
  6. Ramon

    Nalon Viper 2.5cc CI Engine

    Andrew A link to the book (disc) designs for free down load are actually on here courtesy of Ken Croft, one of the engine boys. A quick google found this Go to RCLibrary : Motor Boys International Model Engine Plan Book title : download free vintage model aircraft title That should help...
  7. Ramon

    Nalon Viper 2.5cc CI Engine

    Agreed - if you are making your own the expanding area needs only to be sufficient to provide the grip. The rest of the mandrel should be as close a tolerance as you can get and particularly so when doing the front bearing housings either on a case or a separate crankcase front - the plain part...
  8. Ramon

    Nalon Viper 2.5cc CI Engine

    Hello Peterha I always cut the slits with a standard hacksaw (or a junior one if very small - I have made them as small as 1/8 diameter but just the one slot in that case) On a couple of larger diameter ones made I cut three slots but most at two at 90 degrees by eye. I was shown this tip many...
  9. Ramon

    Nalon Viper 2.5cc CI Engine

    Hello Patrick, In answer ..... 1, Yes best if done with a 45* cutter having gashed the slot with an endmill to relieve the bottom. Do the groove and clamp first. Turn a piece of steel to a parallel dimension (no taper) and clamp the part to it then face the bolting face with very light cuts...
  10. Ramon

    Nalon Viper 2.5cc CI Engine

    Hi Pat, I'm not keen on using a block to hold in the four jaw for a couple of reasons. Even with careful set up there is no 'absolute guarantee' that the shaft is co axial so the pin could, might, be off to the shaft. However slight that is not a good thing to have. Obviously it would have far...
  11. Ramon

    Nalon Viper 2.5cc CI Engine

    Hi Patrick, Yes good to see you back on this again. Re the mandrel. You will get a far better grip if you put four cuts in rather than two. Secondly it's best if the cuts do not go past the work piece. I always turn the mandrel over size then tap and deeply centre before cutting - the actual...
  12. Ramon

    Back Spot Facing Tool

    Hello Mark - I remember it well - work that is, and how it could get in the way of more 'important' things ;) If you made your cutter from silver steel did you quench it in water ? (as you are normally supposed to) I ask as I find it's much better to do it in oil and not to temper it - very...
  13. Ramon

    Back Spot Facing Tool

    Mark - I have made the McOnie but didn't spotface the cylinder bolt holes - used studs instead. Here's a reverse spotfacer made recently - The drive is the pin held inplace with the blob of blue tack! I have a sometime made a reverse countersink for something just loctited to an 8BA bolt...
  14. Ramon

    Nalon Viper 2.5cc CI Engine

    A good start Patrick 👍 Given that you are making two a drill jig that could fit both case bore and front and back housings would be a well considered way to ensure compatability. Second option would be to wait until after the bores are done then do them on the mill using co-ordinates - much...
  15. Ramon

    Squaring off the bottom of a blind hole

    Well I did say I was a dynasaw :) I'm speaking from a home workshop point of view based on working experience with non CNC machines. With the advent of CNC which after all from a production point of view is a relatively recent but incredible advance in machining techniques and particularly so...
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