Maudslay Marine Engine

[Ramon Wilson]

Jason - if this is made right you don't need a spring as well.

The fatter section O ring serves as this as well as providing the seal.  Letting the faces float may be a benefit but it's much better to ensure the squareness of the face to the pivot - in my opinion 

Tug

[cfellows]

I've changed gears here.  Instead of the rotary reversing valve, I'm changing over to a simple, sliding spool valve.





The inlet will be the middle of the edge and the exhaust will be out each end.  Not as elegant as the rotary valve, but a lot simpler and, hopefully will work without leaking.

I think the problem with the o-rings was that the groove wasn't deep enough and was keeping the rotary disk from fully contacting the stationary block.  The only problem I can think of with the prior design, without the o-ring, is that one of the surfaces must have been dished or warped.  Hard to diagnose.

[cfellows]

I got the spool reversing valve installed and it works without any leakage.  But I'm back to the original problem with the rotary engine valve.  Air is  leaking from the high pressure side directly across the valve thru to the exhaust side.  I thought I had a pretty good fit on the valve but maybe I can make it better.

Chuck

[cfellows]

Just wanted to let you guys know I'm not done with this thing.  I ordered a set of Flexolaps and some lapping compound.  I'm going to remake the rotary valve and lap it as well as lapping the valve bore in the valve block.  I'm hoping by lapping everything I can eliminate the o-rings. 

Chuck

[Johnmcc69]

 
I've never seen you leave anything unfinished Chuck, take your time...

 You'll get it. I admire your perseverance & patience.

 
John

[cfellows]

I've got the valve block bore lapped, I think.  And now I've cut the new rotary valve to about .001" over-sized.  At some point I'm going to have to cut the inlet and exhaust groves in the rotary valve body. 



The question is this, do I cut the grooves in the valve body before or after I've lapped it to match the bore of the valve block?

Kind of need all the help I can get at this point.

Thx.. Chuck

[Craig DeShong]

No expert here Chuck, but I would think the lapping should be yours last step?

[cfellows]

On advice from another forum, I have decided to sleeve the valve block with a steel sleeve.  I think lapping the steel sleeve will be a lot more controllable and there are a lot more options for material to use for the lapping tool.  And, if I screw it up, I don't have to make a whole new valve block.



The sleeve is made from drill rod, is 7/16" OD and 3/8" ID.  It's been reamed to .375", but hasn't yet been lapped. 

Chuck

[b.lindsey]

No advice to speak of, but still interested and following Chuch.

Bill

[10KPete]

I think that is an excellent move, Chuck. Having to remake the cylinder would really be a pain.

Watching 'til the thing runs,

Pete

[cfellows]

Thanks, guys.  I started working on the ID of the sleeve.  I first used 400 grit, then 600 grit wet or dry sanding strips wrapped around a piece of slotted aluminum rod.  That removed pretty much all the machining marks left by the reamer.

Then I began lapping with the brass barrel lap and diamond paste.  I got as far as 14 micron by the end of the day.  The finish looks really good.   The bore, as near as I can measure, is perfectly circular and of uniform, .376" diameter.  Tomorrow I'll examine the bore more closely to see if there are any imperfections.  I'm kind of stabbing in the dark with this process and have limited ability to measure results. 

If anyone has any suggestions on how to measure my progress or improve my chances of success, I'm open to suggestions.

Chuck

[cfellows]

This is the kit of diamond paste I'm using.  Bought it a number of years ago and haven't used it very much.



This is a set of Starrett bore gauges that I have. 



I'm using the largest one, which goes up to 1/2 inch to measure the bore.  It passes through the bore with consistent resistance, one end to the other, that's why I think the bore is uniform diameter.

Tomorrow I might try the 10 micron diamond paste to see if it shows up any imperfections.

[cfellows]

I got the new, lapped valve installed and the engine back together.  With all the trials  and tribulations with the lapping, I wasn't at all confident that I had accomplished anything.  But, I gotta say, I'm thrilled with the results.  The amount of leakage throughout the engine is now pretty minimal, far better than before I started modifying it to be reversible.  And, in the end, I didn't use any o-rings on the rotary valve.  I may not be an expert at it, but I am definitely a big fan of lapping now.

Video coming next.

Chuck

[zeeprogrammer]

I got the new, lapped valve installed and the engine back together.  With all the trials  and tribulations with the lapping, I wasn't at all confident that I had accomplished anything.  But, I gotta say, I'm thrilled with the results.  The amount of leakage throughout the engine is now pretty minimal, far better than before I started modifying it to be reversible.  And, in the end, I didn't use any o-rings on the rotary valve.  I may not be an expert at it, but I am definitely a big fan of lapping now.

Video coming next

  Looking forward to the video. It's a really good looking engine.

[cfellows]

Thanks, Zee, probably one of the best models I've created.  I'm really, really happy with the way it turned out.

Here is a picture of the lapping tools I made and used.  A bit crude, perhaps, but boy did they work!



The top image is the OD lap.  It's a 13/16" brass disk, 3/8" thick with a .385" hole in the center.  I made the slits with my 4x6 bandsaw.  I used a die holder to hold it and squeeze it together to adjust the diameter.  To lap the stainless steel valve, I started with fine, clover silicon carbide lapping compound, then moved on to 20 micron diamond paste for the finish.  I was able to get get the diameter to within about a tenth across the 5/8" length and got a nice finish.

The ID lap was made from a piece of 3/8" diameter aluminum rod.  I used a .032" slitting saw to make the axial slits in from both sides.  The slits connect for about 75% of the length.  I center drilled a #29 hole from the end thru to the center of the slit.  Then I tapped it for an 8 -32 SHCS.  The short piece of sharpened rod is 1/8" drill rod.  By inserting the drill rod and the screw, the point pushes the slits apart when it reaches the end of the center drilled hole.  I found this to be very nice lap, able to adjust the diameter in pretty fine increments.  I had tried many different lapping compounds on this piece, but in the end, finished it up with some Timesaver yellow lapping compound that Terry Mayhugh had given me.  I mistakenly mixed the powder with water instead of oil, but it seem to work fine and give me a nice, uniform finish. 

I was concerned about the fit because when I was all done, the valve slipped into the valve block with little or no resistance.  But I must have gotten a good fit because it isn't leaking any air that I can tell.

Chuck