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Old 05-22-2020, 10:03 AM
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johnbright johnbright is offline
Join Date: Aug 2010
Location: Newport News, Va
Posts: 436
Default re-sharpening the reamer is necessary

I successfully reamed for the tapered pin:
  • I'm not a machinist, YMMV.
  • Sharpening the reamer with a stone was necessary and worked great. I have a Norton FF724 stone that looks like the one ebay calls "knife blade file sharpening" "stone" or "file". Should be ~$20.
  • Should have sharpened reamer sooner than I did.
  • Drilling was done with a hand drill.
  • Lubricated generously. I used a mix of engine oil and STP because I had it. Type of lubrication might not be critical; perhaps pipe thread cutting oil is a good choice.
  • Reaming was done with a T-handle mechanic's wrench with a 1/2 to 3/8 adapter followed by a 3/8 to 1/4 adapter followed by a 12-point 10 mm socket. I figure the t-handle prevents side force compared to a ratchet handle.
  • A large mechanics T-handle is important IMO (but I've seen photos where others used a tap wrench, which is smaller); it allows adequate force and torque to be applied versus a tap handle; the T on mine is 9" long.
  • Be careful not to go too far once you get close. Sharpening the reamer makes it move much faster than when it's dull and it could surprise you. 1/2" per foot taper means taking off 2.6 thousandths" on the diameter moves the reamer 1/16".

Photos here

  • Cleaned up the hole in the gear leg with a 5/16 drill bit which removed paint and burrs.
  • Cut and scraped powder coat from the edges of the bearing surfaces of the gear leg with a razor blade.
  • Cleaned powder coat from the upper bearing ID of the engine mount using MEK and Q-tips where the powder coat blew thru the bolt hole.
  • Cleaned up the holes in the engine mount with a 5/16 drill bit in assy with the gear leg. Both had powder coat and one was small.
  • Drilled the engine mount and gear leg assy with an 11/32 bit. Inserted a 5/16 AN bolt from the opposite direction to line up the assy; the drill bit pushed it out as it progressed. Ran the drill slowly and pushed hard so it was always cutting to prevent heat hardening the material.
  • Reamed the hole thru the assy of the engine mount and gear leg until pin shoulder protrudes 1/16" when it's pulled down with the nut. Cleaned chips out of reamed hole with Q-tip. Counterbore in taper pin washer is 1/8".
  • Removed, cleaned, relubricated the reamer frequently. It cut well at first with the assy on a bench attached to a wall, pushing up to maybe 30 lbs (much less at first before the cone is developed), then it stopped cutting. I put the assy on the floor so I could push harder, over 100 lbs I guess, and it cut. It stopped cutting when I was almost finished so I stoned the reamer and then it cut so fast I had to be careful not to go too far. I went back and forth about 3/4" with the stone eight times on the inside of each flute which worked great but I'm thinking fewer strokes would have worked.
  • You can hear when the reamer is cutting and of course you get chips.
  • Tightened the nut just enough to get the slack out, more than finger tight but less than snug. Then went to the next flat that lined up the nut slot with the cotter pin hole.
  • Removed .016 from the AN320 nut bearing face, to get the the cotter pin in, with a vixen file because I didn't want to ream too far. Slid the nut on the stationary file while rotating frequently rather clamping the nut and moving the file. Figure eighted the nut face with sandpaper and broke hex edges with Scothchbrite wheel. Maybe an AN310 nut would be better but having some regular and thin washers on hand would be good in that case.
John Bright, RV-6A, N1921R, at FWF
O-360, 8.5:1, vert sump, dual SDS EFI EM-5-F
Z101 as a template, links

Last edited by johnbright : 11-18-2020 at 08:39 PM.
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