Author Topic: Pottymill horizontal engine build  (Read 79558 times)

Offline Roger B

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Re: Pottymill horizontal engine build
« Reply #135 on: April 13, 2015, 07:55:08 PM »
That's a good result after a lot of handle turning  :ThumbsUp:  :ThumbsUp:
Best regards

Roger

Offline arnoldb

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Re: Pottymill horizontal engine build
« Reply #136 on: April 13, 2015, 08:46:52 PM »
Very well done Todd - machining out a flywheel like this for the first time is quite a challenge, but you did everything right by going about it slowly and methodically  :ThumbsUp:
You'll find it's much easier the next time around  ;)

As to mounting it - yes, the simplest way is a grub screw, and I was about to point you to this post of mine showing drilling and tapping at an angle for a grub (set) screw...
However, going back through your posts, I don't think you'll be able to hold the flywheel in your vise as shown in my post, as it seems a bit too big for your vise.  So you might have to devise a way to clamp the flywheel directly to the mill table at an angle, and as I'm not sure what you have available in your shop, that might prove a mission on its own to figure out  :)
Anyway, if you decide to go the grub screw route, an angle of about 30 degrees from vertical works nicely to allow for clearance for tooling.  It also complements the tapered tip on most grub screws causing less scarring on the shaft when it's tightened.  Just use a small center-cutting milling bit to spot a flat face before spot drilling and drilling the hole to threading size to prevent the drill bit wandering.

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 sbwhart

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Re: Pottymill horizontal engine build
« Reply #137 on: April 14, 2015, 06:32:47 AM »
Great job with the flywheel Todd  :ThumbsUp:.

I just threaded the end of the crank shaft then just a couple of washers and a nut is all you need to bolt it to the shaft.

Like this




If you want to go the grub screw route, glue it to a suitable size shaft and hold onto the shaft in the vice at a suitable angle as Arnold suggested, drill and tap, then heat the shaft up a little to release the glue a sharp tap with a drift should than knock the shaft out, clean away any glue residue:- job done.

Hope this helps

Stew
A little bit of clearance never got in the way

Offline 90LX_Notch

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Re: Pottymill horizontal engine build
« Reply #138 on: April 14, 2015, 11:02:56 AM »
Todd-

This is coming along nicely.  The blue tape idea is a great one.

-Bob
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My Engine Videos on YouTube-
http://www.youtube.com/user/Notch90usa/videos

Offline NickG

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Re: Pottymill horizontal engine build
« Reply #139 on: April 15, 2015, 07:25:53 PM »
Nice work, I used the method Stew described which was good, nice and easy and better grip than the grub screw but on yours I would probably do the grub screw now as it would put stress on the crank when threading.

Offline tinglett

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Re: Pottymill horizontal engine build
« Reply #140 on: April 19, 2015, 03:18:03 PM »
Much prefer your flywheel to my casting from RDG. Lot of
Work in it mind you. Have you thought about running around the spoke edges with a 45 dog angles cutter? I haven't got one but have seen used to good effect - tried with a csk bit to put chamfered edges on but that didn't really work!

I did have a thought about this.  I think I'd make the spokes thicker and then a chamfer all around, or roundover, or perhaps ball nose mill or even a straight mill could make a nice effect around the spoke opening.  But for now I decided the flywheel was complex enough for me :).   Maybe next time.

I think I can do the math for curved spokes, too.  That would be challenging (and fun!).  Don posted about this in January: http://www.modelenginemaker.com/index.php?topic=4601

Todd

Offline tinglett

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Re: Pottymill horizontal engine build
« Reply #141 on: April 19, 2015, 03:39:22 PM »
Mounting the Flywheel

I decided to go with the grub screw.  I could thread the flywheel and shaft and I can still go with that as a plan B.

Here's my initial setup.  I bolted down an angle plate at the back of my X table and rested the flywheel against it.  The flywheel is held tight in the the recess of the table with a single hold down.  I thought this should be stable enough for drilling.  I couldn't shift it with my hands, anyway.


Well, I hadn't thought about the forces of an end mill, though.  I used a 2-fluted end mill to form a flat for drilling and found the flywheel was tending to shift.  Before I had a disaster, I stopped to consider how to make a more rigid setup.


I didn't have room for a clamp along the top edge of the flywheel.  I found the mill was trying to force it to the left, so instead I bolted supports in place on the right/left sides to keep it from rolling.  This was enough.  For good measure I used a small quick-grip clamp to squeeze it together.  This probably wasn't needed, but the clamp was handy.  I didn't have a C-clamp big enough.


Now on to milling the flat.  Easy enough.  I had plenty of room for the mill head at this angle.  In fact, I probably could have put a spacer behind the top edge of the flywheel to tip it a bit more vertical.


I drilled and tapped for an 8-32 set screw.  It's hard to believe just a few months ago tapping was difficult for me, and here I am tapping a steel part that had a lot of time put into it.  As I type this, I realize I had no concern at all about this was I was doing the tapping.  Nice.



Hmm...time to head to the home center for a shorter set screw.  But looking good.


And here we go with the proper sized screw.  I chopped up a couple pieces of pine as a stand.  Nothing is bolted down, yet it balances well.  I'll probably go with a simple black walnut stand to match the other engines I've made so far.  It'll look like this, though the bottom piece will probably be a little bigger and chamfered to match the others.


Thanks for checking in.  Not a complicated task today, but important.  I want to keep that flywheel from rolling out the door!   Next is the eccentric mechanism.

Todd

Offline tinglett

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Re: Pottymill horizontal engine build
« Reply #142 on: April 22, 2015, 04:21:38 AM »
The Eccentric

This looked like a particularly fun part to make, and this turned out to be true.   I didn't get a nice consecutive set of hours in the shop, but with a little time here and there over the past few days I managed to get it done.

Its design is a sandwich, much like an Oreo cookie where the "good stuff" is a ring that is able to wobble back and forth without spinning while the outer parts of the cookie are attached to the shaft.  I was thinking it would look particularly snazzy if the ring was made of brass, so this is where I started the journey.

This bit of brass is a little too large, but was close enough.  I had parted it from the flywheel during my pipsqueak engine of a few months back.  That seems so long ago now.  I faced it and drilled a 5/16 inch hole to fit the arbor that I used for turning the flywheel.  The inside of the ring will be bored out later.


On the arbor I was able to turn it down to 30mm diameter.  The thicknesses and diameters aren't that important, but I stuck to the original dimensions anyway.  I didn't want to find I was wrong about this the hard way.



While still on the arbor, I cleaned up the sides and narrowed it to 6mm.  While doing this that darn brass managed to grab and gouge a little.  Grrr.  But still, it will be sandwiched so I decided not to worry about that too much.  I only needed to clean up the sides for part of the diameter because I'll be boring it out to 20mm inside.



After drilling to 9/16 inch (my largest bit) I switched to a boring bar and finished it to approximately 20mm.  I simply used a ruler for most of the measurements, but then switched to a caliper as I neared the end.  I still haven't purchased any tools to measure an inside bore like this.  But this is why I turned the ring first -- I will turn the next part to fit the ring.


And here's the ring.


Now for the outside parts.  The next part will be turned to 30mm diameter also and turned down to fit the ring I just made.  It's CRS (bright) steel that started as 1.25 inch diameter.  I ended up placing it in the inner part of the outer jaws (how else do you say that?).  I probably could have used inner jaws and spaced it out, but this setup was nice and solid -- though I had to worry about those outer jaws spinning around.  I faced it on both sides and got it to final thickness of 8mm.




Again, I drilled 5/16 inch to fit the arbor.  The arbor was a useful thing to make for this project!  I turned it down to 30mm diameter.



Next I turned down 6mm of the thickness.  The goal was to get a nice slip fit for the brass ring I made earlier.  I measured until I got close to 20mm, and then I started using the ring to test as I took off 5 thousandths at a time.


Here I was very close as the ring almost fits.  One more pass.


I got a fit.  Now I needed to clean up the shoulder as it was pretty sloppy.  That's shown in the second photo.



Then I took it off the arbor, chucked it, and bored it to 16mm.  Again, I drilled to 9/16 inch and finished with the boring bar.



And here is the pair.



I'll finish logging this one in another post.   The other half of the cookie fits inside this 16mm bore and has the offset for mounting on the shaft.

Thanks for looking in!

Todd

Offline b.lindsey

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Re: Pottymill horizontal engine build
« Reply #143 on: April 22, 2015, 01:14:13 PM »
I still really like the looks of this engine and the design in general Todd. And on top of that your photos are excellent!!  Looking forward to seeing the completion steps and getting her running too.

Bill

Offline tinglett

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Re: Pottymill horizontal engine build
« Reply #144 on: April 23, 2015, 03:07:00 AM »
Thanks for following along Bill...I am getting near the finish line.  Everything is a little stiff and I fear I may need to remake the piston rod and maybe even the valve rod.  We'll see.  But it's looking as nice as I could ever wish.  Maybe this weekend I'll make a real wood base for it, too.

Todd

Offline tinglett

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Re: Pottymill horizontal engine build
« Reply #145 on: April 23, 2015, 04:06:04 AM »
The Eccentric (part 2)

I was hoping to get this written earlier today, but better late than never :).

In the last post I was building the eccentric which is an Oreo cookie-like arrangement of three parts that fit together.  The good stuff in the middle is a ring that will be drilled and tapped for the eccentric push rod that operates the valve.  In that last post I made the ring out of brass, for the sex appeal of course, and made the simple side of bright steel.   Here I make the other side which includes the eccentric offset.

As with the other side, I started with a hunk of 1.25 inch CRS (bright) steel.  This one is a bit longer as the finished part will be 15mm thick.  I faced both sides roughly and then needed to chuck it with enough material exposed to turn down an 8mm section.  Perhaps I should have used a longer length and parted it off, but instead I decided to give this a try.  I had to space it out and keep it square so I used (literally) my square and couple parallels as reasonably accurate spacers.  Of course I had the power off while getting it setup!  I was a little concerned about the short grip, but I was able to really tighten it down because the other end will be turned and any marks will be long gone before I'm done.



As before I turned it down, but this time was shooting for 16mm to fit the other CRS part I made earlier.  I was careful not to overshoot this time.  I stopped as it got real close to fitting (the second photo).



Now I had to go real slow.  I followed a process I've used a few times on this engine.  First turn a portion of the length down an extra thousandth and test for a fit.  If it didn't fit, I'd finish the pass and repeat.  Eventually the other part fits the portion and I know the rest (about 2/3rd of the length) is one thousandth over.   Unlike the brass ring which was ok to be a sloppy slip fit, I really wanted this part to be a press fit with the other part.   Worse case if I screwed up I could glue it up with loctite, but my goal was to press.  And I didn't want to press too thick a fit because the material needs to go somewhere and I didn't want the brass ring, which fits between these two parts, to seize up in the space.  So it was careful work here.


As I've often done on this engine, I finished up the shoulder with my parting tool.  It was ok to run a little extra deep because the inside of this part won't be seen.  I probably should grind an HSS cutter for this work...but the parting tool worked ok.


Looking A-OK.  But I can't press it now, of course.


Now I flipped it around to do the eccentric part.  The first step, though, is to turn the diameter to 30mm to match the other half of the Oreo cookie.  We wouldn't want the sides to mismatch, would we?  I used my 3-jaw for this since there is no offset, and of course the 3-jaw chuck was already in the lathe.


It's time for the eccentric turning and I had to switch to my 4-jaw chuck.  It's a 5 inch chuck and a little big for this lathe, but working good so far.  I centered it first, and then I pushed it for a 3.5mm offset.  That's 138 thousandths of an inch, so my dial indicator ended up at a full turn and 38 thousandths extra (second photo).



Next I drilled for the 5/16 inch shaft I'm using.  I thought drilling was best as a start so I can easily see it was offset the way it should be.  The shaft actually measures at about 0.306 rather than 0.313, so I drilled to an N bit and then reamed it to 0.3115.  I figured it wouldn't hurt to be closer in diameter because the 5/16 inch drill bit will probably go oversize.  I'm sure drilling would have been fine.   This was a "what the heck" thing:).




And now I could check the fit using the engine itself.  Power is off of course.


Now I started turning down the outer edge.  It was already located correctly so this was just a matter of dealing with an intermittent cut until I got down to 16mm, which was a fairly arbitrary measurement anyway.  That is, it looks nice.


And here are the three parts now.  The new one on the right should press fit inside the one on the left.


The new part needs a set screw to clamp onto the shaft.  I used a 3/16 inch end mill to make a flat, then drilled and tapped as shown in these photos.  I had to use an undersized starter drill to avoid running into the side of the part.  I tapped it using an 8-32 set screw to match the flywheel.





Before pressing the assembly together, I needed to drill and tap the brass ring to accept the eccentric rod which I haven't created yet.  I decided to go with a 4-40 thread, even though 5-40 would be better.  I don't have 5-40 taps and dies yet.  They don't seem to be very common, though I do plan to buy a set soon.  I plan to use a 1/8 inch rod which would be a perfect fit for a #5.  But 4-40 should work fine.





Now for the big moment.  It's time to press the assembly together.  I used my mill vise and as I turned the vise crank I kept spinning the brass ring around to make sure it stayed loose.  It did.  If it hadn't, my plan was to stop quickly and pull it apart before I was at the point of no return.  Well, that was the plan...no proof it would work.



Perhaps I should have made the spacing between the outsides a little tighter, but I didn't want to trap the brass ring too tight.  And I really think the brass make it look nice.


And here it is installed on the engine.   This baby is wanting to run pretty soon now!


My apologies for the volume of pictures, but I know you guys like to see them, and I thought it's good once in a while to show I really do go through all the steps with starter drills, drilling, tapping, etc.  This build log is for the beginners out there after all.

Todd

Offline tinglett

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Re: Pottymill horizontal engine build
« Reply #146 on: April 23, 2015, 02:06:55 PM »
It occurs to me now that in recent posts I've been saying arbor when I should be saying mandrel.  In my copious free time I'll go back and fix those references.

As far as I can tell the word "mandrel" is most used as a shaft that holds spinning work while the word "arbor" is a shaft that holds a spinning tool.  In my case I was holding a flywheel or eccentric disc which is the work.  I know the words are nearly interchangeable, but I may as well get it right for future readers :).

Todd

Offline b.lindsey

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Re: Pottymill horizontal engine build
« Reply #147 on: April 23, 2015, 02:08:34 PM »
That's one handsome engine Todd...can't wait to see it running ...soon as you say!!

Bill

Online Jo

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Re: Pottymill horizontal engine build
« Reply #148 on: April 23, 2015, 02:21:48 PM »
It occurs to me now that in recent posts I've been saying arbor when I should be saying mandrel.  In my copious free time I'll go back and fix those references.

The Hardinge Operator manual uses the term "arbor" to refer to the mounting for the work, so that is good enough for me.

Jo
Enjoyment is more important than achievement.

Offline tinglett

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Re: Pottymill horizontal engine build
« Reply #149 on: April 23, 2015, 02:44:53 PM »
It occurs to me now that in recent posts I've been saying arbor when I should be saying mandrel.  In my copious free time I'll go back and fix those references.
The Hardinge Operator manual uses the term "arbor" to refer to the mounting for the work, so that is good enough for me.

Well that's official enough for me to use an excuse for avoiding edits when I should be working on the engine! :)

Todd

 

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