Author Topic: Arnold's take on the MEM Corliss  (Read 134635 times)

Offline black85vette

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Re: Arnold's take on the MEM Corliss
« Reply #15 on: January 20, 2013, 12:39:44 AM »
Very cool to see you start this.   I like the design but it is much better for us less experienced to see how to go about it and what it is "supposed" to look like.

Offline zeeprogrammer

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Re: Arnold's take on the MEM Corliss
« Reply #16 on: January 20, 2013, 01:12:19 AM »
He he. Not that there's any pressure Arnold.  ;D

I can't help but feel you've stepped in it...but unlike some of us...you'll come out clean.

Very much looking forward to your build.
Carl (aka Zee) Will sometimes respond to 'hey' but never 'hey you'.
"To work. To work."
Zee-Another Thread Trasher.

Offline propforward

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Re: Arnold's take on the MEM Corliss
« Reply #17 on: January 20, 2013, 01:30:34 AM »
I shall be following your build as well Arnold. You have a great writing style, informative and easy going, and modest as well. You really turn out some great work, and your explanations are exceptionally helpful to the novices among us. Much appreciated.
Stuart

Offline metalmad

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Re: Arnold's take on the MEM Corliss
« Reply #18 on: January 20, 2013, 01:33:02 AM »
Every Arnold Build is Fun to watch
Will be taking along
Where does the Spark plug go??
Pete
A little bit every day, sometimes the same little bit

Offline swilliams

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Re: Arnold's take on the MEM Corliss
« Reply #19 on: January 20, 2013, 02:29:21 AM »
I'm watching Arnold. This will be fun

Steve

Offline NickG

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Re: Arnold's take on the MEM Corliss
« Reply #20 on: January 20, 2013, 09:26:31 AM »
Agree with everyone else, this will be great to watch. Well done Arnold  :ThumbsUp:

Offline arnoldb

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Re: Arnold's take on the MEM Corliss
« Reply #21 on: January 20, 2013, 05:31:16 PM »
Wow - what an overwhelming response - thank you everyone  :praise2:

Vince, yes, I'll be using the 24 factor for all dimensions.  That brings nearly all measurements to easy-to-use metric sizes for drilling, reaming and fasteners.  1/4" -> 6mm and 1/8" ->3mm etc.

Carl may be very right about me stepping in it...  I'm already wishing my cylinder block was a bit of cast iron rather than this horrible mild steel I have going.  But then, I have been known to do things the hard way sometimes...

I finished boring the cylinder to size, but got a really cruddy finish - the thin boring bar flexed far too much and I just could not get a nice even finish with it - no matter what I tried with cutting fluid and feeds and speed changes:


So stuck the Dremel's flex shaft on the toolpost with a grinding stone.  The flex shaft handle is long and thin, and easily provided enough range to grind up the entire length of the cylinder bore to a better finish.  The bore will require some lapping later on though:


Off to the mill and rotary table with the chuck.  I used a DTI to locate one side of the workpiece parallel to the X axis and zeroed the RT there:


This is an important face on the workpiece - as this face is very square to the cylinder bore, I want to mount the cross-head on it, so the bolt holes must be on the bigger circle as on the  "right view" of the cylinder block on the plans.
I nearly started drilling the holes with just the 19.5mm offset dialed in on the X axis for the bolt circle and cranking the RT 45o for each hole...  Something nagged at the back of my mind though.  I've come to pay attention to these nagging thoughts.  So I checked things, and I would have drilled the holes 22.5o out of position.  It's not a biggie, but the bottom and top hole could possibly go into the area needed for the steam ports if drilled slightly too deep.  So I just made a new list of angles to drill each hole at to get them in their proper locations.  I used a permanent marker to roughly dot where each hole should approximately be to help prevent any brain fart, and then drilled the holes:


The workpiece was still a bit long, so I moved things back to the lathe and flipped the workpiece in the chuck and faced it off to length.  I didn't bother to clock it up true in the chuck.  If I wanted to drill the bolt circle for the cylinder head using the RT I should have, but I'll use the DRO's PCD function later to drill these holes:


Shop time stopped there for today - it was only a short session:


I'll see if I can get anything done during the week, otherwise there won't be any progress till next weekend.

Kind regards, Arnold
Building an engine takes Patience, Planning, Preparation and Machining.
Procrastination is nearly the same, but it precludes machining.
Thus, an engine will only be built once the procrastination stops and the machining begins!

Offline NickG

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Arnold's take on the MEM Corliss
« Reply #22 on: January 20, 2013, 05:38:45 PM »
Nice work Arnold, I hadn't realised it was quite so big. Cast iron is generally much nicer to work with. I always struggled getting a good surface finish on steels, think the grade of steel plays a large part. Not so bad on the Harrison now but boring is always harder too.

Offline tel

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Re: Arnold's take on the MEM Corliss
« Reply #23 on: January 20, 2013, 07:05:17 PM »
Yes, I agree about the cast iron - and went tro great lengths to use it on my version.

Have you considered how the holes for the cover are going to impact on the valve bores laid out that way Arnold? I oriented mine the other way to minimise it. I also used the 'big' bolt pattern on both ends of the cylinder as being more in keeping with 'real' practice.



« Last Edit: January 20, 2013, 07:12:03 PM by tel »
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Offline arnoldb

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Re: Arnold's take on the MEM Corliss
« Reply #24 on: January 27, 2013, 06:03:50 PM »
Thanks Nic.  The type of steel can make a big difference to surface finish.  Unfortunately, I have to make do with what I can find locally, otherwise I have to order in at huge expense...  There's one up side though; trying my best to get good finishes in the mostly poor steel I can get has taught me a lot about  what's involved - I'm pretty happy with the finishes I can get in most non-ferrous metals, 303 stainless and silver steel now  :) .  And yes, it's a big engine - more than double the size of the Popcorn I built.

Tel, thanks mate; yes, I did consider the holes' impact on the valve bore, and drilled them just shy of it.  Looking at your photo, I can now see that I must have had a brain-malfunction when I thought the bolts at the top and bottom holes would interfere with the steam passages, so it might just be better locating the bolt holes like you did  :ThumbsUp: .  I was also considering drilling the bolt patterns both ends with the bigger bolt pattern.  I see you re-arranged the bolt pattern on the steam chest cover as well...

I had a bit of a rough week, and was feeling out of sorts yesterday, so stayed away from the shop and did some menial tasks around the house.  This morning, I decided I'll face the heat and set off to the shop to drill some holes.

After deciding which side of the steel block would become which, I drew some markings on it (to prevent a brain-fart), and set it up in the mill on top of two of my crude home-made parallels to raise it a distance off the vise bed.  This is so that there would be room to pass a reamer through the valve bores.  Then I located it's center on the DRO and also set the vise back-stop up to keep position, as it would be rotated a couple of times.  I started off machining on the "Front" face; this is where the valve gear would be mounted, and I wanted things as accurate as possible here.  My main concern was that the holes for the valve bores might wander slightly as they pass through the block, and I want them accurate at the valve gear side, mostly for the fact that each valve gets a cover with a through-hole on this side, and I want to keep these to a close tolerance.  The valve covers at the "Back" side are just flat plates, and if the hole wandered a bit, it would not matter.
Better stick a photo in, before you get too bored:


I've so far enjoyed having the DRO on my mill very much, but today, I really appreciated it.  It's bolt circle function got a good workout; first was the holes for mounting the valve gear - a four hole bolt circle for tapping M3 to mount the valve pivot smack bang in the center of the face.  With the DRO's absolute coordinates set to 0 there, it was easy to move to each of the valve hole centers, set relative coordinates to zero, and drill 5.5mm through, followed by 5.9mm and finally the 6mm reamer.  My reamer is a bit short to completely do each hole though...  At each hole, this was followed by four 1.6mm holes (to tap M2 later) in the valve cover bolt circles.  Everything went well up to the second last 1.6mm hole for the face...  While drilling it, I shifted position slightly, and momentarily applied too much pressure to the feed arm.  SNAP - one broken 6mm drill, with a section stuck in the hole  :facepalm2: :


It's the first drill I've broken in a long time.  It was due to happen at some point, so no use getting upset at it.  Santa arrived very late in my house this year, but brought a nice package full of new milling cutters of all shapes and sizes from Hong Kong about two weeks ago.  Amongst that are ten 1.5mm carbide slot mills that "Peter" popped in free of charge, so that was one option to get rid of the bit of drill left in the hole.  However, that could be messy, and with a tiny bit of the broken bit left sticking out, I decided to gently try and coax it out with a pair of needle-nosed pliers.  After dropping a bit of tapping fluid on it to help lubricate in the hole, I lightly closed the pliers on it while simultaneously twisting the pliers anti-clockwise.  On the second grab, I felt something give, and the bit of drill had twisted out just enough to get a better grab on it to remove it:

I was very careful not to drop the bit of drill, as I wanted to see if it was the entire piece.  By carefully checking the end, I could see that it was the entire bit, and thus there were no other significant bits left in the hole.

That was the last of my brand new 1.6mm drill bits, so I grabbed a more-used one, and finished drilling the holes; a lot more carefully!


After flipping the workpiece 180o on it's X axis, I drilled the bolt circles for the Back face around the valve holes:


Another 90o flip, and I drilled the bolt pattern for the top steam chest cover:


I was about to change the drill chuck for the collet chuck to start milling out the steam chest, when I decided I could just as well finish all the holes on the bottom as well, so I did that:


While the workpiece was oriented this way, I started milling out the bottom "exhaust" chest.  Good practice for doing the steam chest on the top, and I got to play around with another new bit from "Peter" - a 10mm carbide slot mill.  I'd decided on getting rid of most of the metal with a 10mm mill leaving lighter machining clearances for a 6mm mill to form the final size of the pocket.  Here I paused to test the depth of the pocket with my once-shiny home-brew depth gauge.  Back when I made it Marv suggested I add a threaded hole to it to screw a bolt through to measure pockets in cases just like this.  Thanks Marv! :

It's important that both the steam and exhaust pockets on this design are done to the correct depth, as it influences the timing of the engine.

You'll see in the photo above the pocket looks too short - and it was.  I deducted the whole cutter diameter from the needed X dimensions, rather than just half the diameter   :-[ .  After milling out that bit more with the 10mm mill, and switching to a 6mm mill, the pocket was machined to size and final depth (45x12x7.5mm):


I felt tempted to mill the top steam chest as well, but it was really hot here and I was getting a bit tired, so I decided not to tempt fate with more machine work.  So I finished hand-reaming the valve bores in the big vise:


It's starting to look like a block of Swiss cheese, and there's another bolt circle to drill for the cylinder cover on the left face, as well as the steam ports.  And somehow I feel I should have built a tapping stand first  :facepalm2: :


I'll see what I can get done next weekend; machining during this week will be out, as I'm going on a business trip.

Kind regards, Arnold
Building an engine takes Patience, Planning, Preparation and Machining.
Procrastination is nearly the same, but it precludes machining.
Thus, an engine will only be built once the procrastination stops and the machining begins!

Offline Jo

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Re: Arnold's take on the MEM Corliss
« Reply #25 on: January 27, 2013, 06:19:45 PM »
Excellent progress Arnold  8)

And a good save on that drill. You didn;t even have to move the work. :ThumbsUp:

Jo
Usus est optimum magister

Offline tel

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Re: Arnold's take on the MEM Corliss
« Reply #26 on: January 27, 2013, 06:56:01 PM »
Going along nicely Arnold! Alas, mine is still sitting untouched where it has been for several weeks - I seem (as is usual this time of year) to have grown a tractor on my Gluteus maximus.
The older I get, the better I was.
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Offline swilliams

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Re: Arnold's take on the MEM Corliss
« Reply #27 on: January 28, 2013, 11:02:55 AM »
Looking good Arnold. Yours too Tel, hopefully you get that bucolic boil off your bum soon and get back in the shop  :Jester:

Steve

Offline black85vette

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Re: Arnold's take on the MEM Corliss
« Reply #28 on: January 28, 2013, 02:30:24 PM »
Wow.   That is an extreme amount of drilling.   Glad you recovered the broken bit!  :cheers:

I see that you drill first and then tap later.   I have broken enough taps (poor technique no doubt) that I drill and then tap each hole one at a time so I am sure that my tap is lined up and vertical.

Looking good.

Offline b.lindsey

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Re: Arnold's take on the MEM Corliss
« Reply #29 on: January 28, 2013, 02:50:30 PM »
Both of these are coming along well!!  Seeing that crosshead attached to the cylinder really makes it start looking like an engine too!!  Heres to getting more shop time and or extricating tractors from posterior areas for both of you :)

Bill