Author Topic: Pottyengineering Horizontal Mill Engine - Imperial - Mike's 3rd Engine  (Read 8060 times)

Offline mikehinz

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Re: Pottyengineering Horizontal Mill Engine - Imperial - Mike's 3rd Engine
« Reply #30 on: November 19, 2018, 01:02:15 PM »
Mike,
I was thinking about building this engine next. Nice work. Where do you get those little tap handles?

I got them from Little Machine Shop.  Search on their website for 'Tap Wrenches, Miniature'.  You get qty 2 of them, one small and the other one very small both for about $12!  To be honest, I also have the two smallest Starrett tap wrenches and i prefer the little tap handles from LMS at the smallest sizes, that is 6-32 and smaller.  Even the smallest conventional tap wrench is too large and unwieldy with too much leverage, at least to me, for tapping small holes.

FYI.

Mike

MIke
Wichita, KS, USA

Offline mikehinz

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Re: Pottyengineering Horizontal Mill Engine - Imperial - Mike's 3rd Engine
« Reply #31 on: November 22, 2018, 01:56:38 AM »
I was able to spent a bit of time in the shop over the last couple of days and made some good progress on the cylinder's 'tricky bits'.  I spent quite a lot of time thinking about the setup needed and the order of operations.  I'll try to illustrate what I came up with in the pix.

Since the 2 flat areas on the cylinder have to be at 90 degrees to each other, the easiest way that i could accomplisht that was to simply place the first milled flat against the fixed jaw of the vise and then space it up with some parallels and just to be sure I didn't mar it, I used a small piece of AL between the cylinder and he moveable jaw.  Then it was a simple matter of cutting the flat to dimension.  i did have to slide the parallels out to get a mic across the part as needed.


Then the other tricky bit that took me a bit of time to figure out was how to get the holes on the flat properly located, since the cylinder is no longer round.  What I ended up doing was to insert a piece  of 5/8" drill rod thru the cylinder and indicate on that and that operation enabled me to move to the centerline of the cylinder on the DRO pretty easily.  The other problem I had is when i drew the part in Fusion 360, there are some strange limitations on where you can put 0,0 when using ordinate dimensions.  So I had to pay attention and offset everything properly in order to get the holes placed correctly.  This pix just shows edge finding on the drill rod and the end of the cylinder.


Then on to drilling the air passage holes from the face and spotting the locations for the piston valve block mounting bolts.


Finishing up drilling the #50 holes to be tapped 2-56.  Since I had qty 8 holes and was worried about drilling too deep, I carefully setup the quill stop so as to avoid any tragedies at this point.


Then tapping all 8 holes 2-56.  Note the spring loaded tap follower and my massive 1.5" long tap wrench!  I tapped as deeply as possible with a plug tap and then follow up with a bottoming tap in each hole. 


Checking the fit of each tapped hole with a 2-56 bolt.


Then on to the operations on the front end of the cylinder.  I didn't take a pix of it, but I did center up the mill on the cylinder hole using a DTI.  This shows starting to drill the 1/8" hole to intersect the air passage hole from the side mounting area. 


Then spotting the 4 locations for the cylinder cover mounting tapped holes.   Since there were only 4 holes and the geometry allowed reference from the center, I just put some linear dimension on the print to work from vs having to rig up the rotary table to do this.


Drilling each spotted location with a #43 drill in prep for tapping.  RPM was about 500, no lubrication and went to a depth of .375"


Then tapping each hole 4-40 using my massive 2.5" tap wrench!


Then the last operation on this end of the cylinder.  I milled a 1/8" slot from the cylinder ID to the air passage.   This is to allow air pressure to flow into the cylinder from the drilled passage.  I used a 1/8" 4 flute carbide end mill running about 2400 rpm.  Once I touched off, I raised the table about .020" per pass and made several passes from the center of the cylinder to the center of the drilled hole until I got to the required depth for the slot.  This worked fine and I could have probably been more aggressive but I didn't want to snap off the only 1/8" end mill that I had on hand!  Sorry about the focus.  I didn't notice that my camera had auto-focussed on the quill rather than the work.


Finally a couple of pix of the cylinder.  First pix is of the flat area that will mount the piston valve block. 


Last pix is the front end of the cylinder with all the operations completed on that end.  Notice that I've marked 'F's all over it to avoid confusing myself on the orientation.  That either proper cautious behavior or a sign of my ever-increasing age, I'm not sure exactly which it is!


All for now.  Tomorrow is a holiday with a later dinner with our daughter and family but I hope to get the cylinder finished up and move on to the cylinder covers, piston valve block, and many parts beyond over the long weekend.

All for now.

Enjoy!

Mike.
MIke
Wichita, KS, USA

Offline crueby

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Re: Pottyengineering Horizontal Mill Engine - Imperial - Mike's 3rd Engine
« Reply #32 on: November 22, 2018, 02:17:15 AM »
Beautifully planned out and done!!


 :ThumbsUp:

Offline Kim

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Re: Pottyengineering Horizontal Mill Engine - Imperial - Mike's 3rd Engine
« Reply #33 on: November 22, 2018, 06:38:56 AM »
Your cylinder is looking great, Mike!
There's a surprising amount of work in those cylinders, isn't there?
Kim

Offline mikehinz

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Re: Pottyengineering Horizontal Mill Engine - Imperial - Mike's 3rd Engine
« Reply #34 on: November 24, 2018, 02:02:44 AM »
Question - Machining a cast iron flywheel - What's the correct process / order of operations?

I started working on the cast iron flywheel that i've for this engine today.  I finished all the cleanup/fettling work on it and started to mount it in the 4 jaw chuck on my lathe.  I reversed the jaws to grip it on the OD of the rim as there's no way to grip it on the ID of the flywheel as my chuck jaws are just too large for this 4 1/2" flywheel.

The question I have is:  What's the best way to go about machining the flywheel so that it runs as true as possible given that it's a casting and there are some bits that just won't ever be true. 

Here's what I'm thinking but please correct me as necessary.

- Mount the flywheel in the 4 jaw by the OD
- Roughly center the OD
- The use some sort of an indicator or fixed pointer on the carriage to get the ID of the rim running as true as possible.  I'm thinking that this area is the most important to true up as it's impossible to machine that area.
- It looks like I'll have a little more than 1/2 the thickness at the OD available to turn. 
- Turn the available OD to get the rough finish off and close to the required diameter.
- Face off the face of the rim to get it cleaned up
- Face off the hub to get flat
- Turn the OD of the hub to get it running true and to the required diameter
- Spot drill, drill thru and ream thru the hub to fit a mandrel, in my case it will be 5/16".  Make sure that the mandrel is a good fit before dismounting the flywheel.
- Turn the flywheel over in the 4 jaw and take the rough surface off the other 1/2 of the OD and the hub and the outside rim of the flywheel.
- Then install the mandrel in the flywheel and remount in the lathe.
- True all surfaces with the flywheel running on the mandrel. 

Please critique the above process.  I'm slightly worried in that I did mount up the flywheel in the 4 jaw and did attempt to center up on the ID of the rim.  But after that it still looks to me like the ID of the flywheel is running out more than I expected, but it's extremely hard to tell with all the other wobbling going on. 

So please give me your input!

Thanks in advance!!

MIke
MIke
Wichita, KS, USA

Offline AOG

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Re: Pottyengineering Horizontal Mill Engine - Imperial - Mike's 3rd Engine
« Reply #35 on: November 24, 2018, 04:05:40 AM »
In my opinion you are looking at this the wrong way around. Your reference isnít the rim itís The hub. More specifically it the shaft your spinning the flywheel around. I would roughly center the hub and clean up one side just enough to make it round and flat on the end so you can get a good grip on it. Then I would flip it around in the chuck and take the other side of the hub to size and drill out the center. Put the flywheel onto an arbor (expanding or superglue what ever you have) and clean up the OD, sides and the other hub. That way everything is concentric to the bore and it wonít appear to wobble.

My two pennies

Tony

Offline john mills

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Re: Pottyengineering Horizontal Mill Engine - Imperial - Mike's 3rd Engine
« Reply #36 on: November 24, 2018, 06:27:24 AM »
when you set the casting up you must look at all the cast surfaces that you cannot machine when it is turning
that is what you see after it is fitted to the crank shaft.All the surfaces you can machine in this setting will run true
and look true but you must bore the hole to make sure it is straight and concentric and it must, be a push fit on the shaft  by hand at least if it is loose or sliding fit when you use a tapper key or grub screw will push it to one side.You can use reamer to finally finish the hole ,the reamer will follow the bored hole .the shaft should then be turned to a push fit.when the second side parts you could not get at in the first setting are to be done if it is on a mandrel then machine the mandrel ,don't move it push the casting on or use locktite only move it when it is finished.preferable that all the visible faces were done in the first setting the rest are not as visible and are not so noticeable .if you move the casting before finishing it s very difficult to reset even using dial indicators.inital setting should be done with a pionter an by eye ,you don't use dial indicators on rough cast surfaces if you value your indicator.

Offline sbwhart

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Re: Pottyengineering Horizontal Mill Engine - Imperial - Mike's 3rd Engine
« Reply #37 on: November 24, 2018, 06:58:30 AM »
I always set it up first in the four jaw chuck and using a pointer on the inside of the rim get this running true as you can taking into consideration its a casting, then set to work on the hub face it up and true its outside diameter up then put in a big centre and drill/bore the centre out. then lightly skim up and shamfer as much as the outside diameter of the rim as you , remove from the chuck. Turn up a mandrel that's a good fit on its bore, mount the wheel on this finish off the other side, and the rim. If you follow this procedure it will be running as true as well as the casting will allow.

Stew
A little bit of clearance never got in the way

Offline Gas_mantle

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Re: Pottyengineering Horizontal Mill Engine - Imperial - Mike's 3rd Engine
« Reply #38 on: November 24, 2018, 07:14:39 AM »
Mike the way I turn wheel castings is as follows.

1) Hold the casting by the outside of the rim in the 4 jaw.
2) Get it running as true as possible at the inside of the rim.
3) Machine everything you can on the exposed face and as much of exposed rim as you can (leave the rim very slightly oversize for now)
4) Drill and ream the centre hole to its its final size.
5) Once happy with the appearence of the exposed face remove from the chuck.
6) Place a piece of scrap rod in the chuck and turn a mandrel to be a very close fit in the hub. Centre drill it for tailstock support if necessary
7) Once the mandrel is turned do not remove it from the lathe until the entire task is finished.
8 )Secure the casting on the mandrel with the unmachined face exposed (Loctite 638 works well).
9) You should now be able to turn all the exposed face and true up the rim across its full width.
10) Finally with everything machined remove from the chuck and apply heat to break the bond and remove the mandrel.

I guess there are other ways to achieve the same thing but that's how I do it and I find it gives good results provided the mandrel is made as a good close fit.

Edit - Stew beat me to it but said pretty much the same thing 😀
« Last Edit: November 24, 2018, 07:17:58 AM by Gas_mantle »

Offline mikehinz

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Re: Pottyengineering Horizontal Mill Engine - Imperial - Mike's 3rd Engine
« Reply #39 on: November 24, 2018, 02:18:05 PM »
Thanks to everyone for the advise!  I'll get out to the shop as soon as it warms up and a bit and will get the flywheel finished, one way or another!  I'll post pix of the results later today.

Mike.
MIke
Wichita, KS, USA

Offline mikehinz

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Re: Pottyengineering Horizontal Mill Engine - Imperial - Mike's 3rd Engine
« Reply #40 on: November 24, 2018, 11:16:23 PM »
Since I managed to do a fair bit of work over the past couple of days, I'm going to break this into 3 different posts just to avoid too much of a long run-on.

First up is the piston valve block.  I started with a piece of .75" x .75" AL cut to rough length.  I ended up with AL for this by default as I couldn't find any reasonably priced smaller rectangular or square CI bar stock.  I want to look around a bit more as it would be handy to have on hand.  I figured though since this engine will probably only run on air and only intermittently, AL would be OK.

This pix is just of taking the stock to the required dimensions using my old Valenite CentreDex end mill.  Old but it makes a nice finish!


Stock to size shown against the print.


About to do the end that takes the piston valve rod packing gland.  This also will be the start of the 1/4" bore for the piston valve.  Squaring up the stock in the vise.


I'd just drilled thru 1/64" under 1/4" in prep for reaming and just started drilling with a "J" bit to .200" depth for the packing glad.


Reaming thru the piston valve bore with a .250 reamer.  I plan to closely fit a bit a drill rod for the piston and lap the bore to achieve a good fit. 


Tapped the 2 holes for the valve rod packing 2-56 and checked the fit in this pix.


First end completed and shown on the print.


Starting on the exhaust ports on the bottom of the valve body.  After edge finding, and spot drilling, I just drilled thru to the main bore with a 5/32" bit.  Worked fine.


Just finishing the air inlet side.  I'm just finishing running a bottoming tap into the air inlet port fitting area.  I'm using my typical setup.  Spring loaded tap follower and my smallest tap wrench (1.5" long).



The air inlet side shown on the print.


Starting the trickiest side, that is the air passages to the cylinder.  This face will also have qty 8 clearance holes for the 2-56 bolts that will fasten the piston valve body to the cylinder.  Notice that I put a black mark here indicating 0,0 on this piece.  Since this part is machined from all sides, its important to make sure you're working from 0,0 on the print and that changes from lower left to upper left depending on which face your working.  Hence the reminder mark!   This shows drilling the qty 2 5/32" air passage holes.


I didn't show drilling all the thru holes but it went well.  Just had to pay close attention to the print and the DRO as I moved from hole to hole. Shown is one orientation on the print.


Showing an elevated view on the print.  You can see the air inlet on the top and the piston valve packing and piston valve bore on the front and the thru holes for mounting on the side. 


So this rather complex part is now done!  i did a quick check against the cylinder and it all seemed to fit correctly.

More in the next post.

Enjoy!

Mike.
MIke
Wichita, KS, USA

Offline Ye-Ole Steam Dude

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Re: Pottyengineering Horizontal Mill Engine - Imperial - Mike's 3rd Engine
« Reply #41 on: November 24, 2018, 11:44:37 PM »
Hello Mike,

Some really nice work and documentation with the photos.

Have a great day,
Thomas

Offline mikehinz

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Re: Pottyengineering Horizontal Mill Engine - Imperial - Mike's 3rd Engine
« Reply #42 on: November 24, 2018, 11:48:30 PM »
Next up are the front and rear cylinder covers. 

i started by mounting in the 4 jaw a scrap piece of 1.75" OD AL round bar that I had on hand.  Shown is after turning the major OD to 1.375" and establishing a 1/32" thick centering feature on the side that goes to the cylinder.


Then i drilled a shallow center hole on the inside just in case I needed it for centering later.  It turned out that i didn't need it, but it didn't hurt anything either.


This is the cover that the piston rod will go thru.  That protrusion will be threaded on the ID for the packing nut.  I'd already drill thru or the piston rod and I'm getting ready to drill the larger hole to be threaded.


Putting a bit of a bevel on the ID of the bore just prior to threading.  I find this greatly eases the tapping process.


Tapping 5/16-24 for the packing nut.  I just put the tap in the tailstock chuck and kicked the lathe out of gear and rotated the check by hand.  I'd drilled for 75% threads and used both a plug and bottoming tap on this op.


Breaking all the sharp corners and putting a slight bevel on the edges of the cover.


Parting off the bottom cover.  I did this dry at about 430 rpm.  Worked fine.  I left the part a bit long as I'll turn it around and finish it to length here shortly.     Parting tool is a 3mm width carbide insert type.


This is the cylinder cover that the piston rod goes thru.  I turned it around and gripped it with a 7/16" 5C collet.  Trimmed it to length and cleaned it up with a bit of Scotch Brite.


For the other cover there's not a handy protrusion to grip so I used a 5C 'pot' collet.  Shown is boring it to 1.375" ID with the little 'stop pin' installed.  The collet is tightened at this point and brought to exact size.  Then when the collet is released and the stop pin removed, the part will be gripped correctly when the collet is tightened.  I bored about 1/8" deep which is plenty for some light facing cuts.  These sorts of collets are extremely handy for some operations.


The cylinder cover installed and being faced and the edges beveled.  Notice that i have plenty of clearance for any ops needed when using this sort of work holding.


Then to drill the holes in the covers, I mounted the pot collet in a collet block and squared it up in the mill after tightening the work in the pot collet. 


Centering up the work in the mill.


Drilling the thru holes for the mounting bolts.  This involved moving from 0,0 to each x,y position.  I'd put both the PCD and x,y coordinates on the print.  This seemed easier for just 4 holes.


Centering up the other cover.


The finished covers on the print.


And finally 4 pix of the assembled parts so far.
Pix 1


Pix 2


Pix 3


Pix 4


I like the appearance of this engine quite a lot so far.  I think the scale model fasteners with the brass washers under each one look good, if not exactly historically correct!  The fasteners in the pix are either 2-56 or 4-40, all from American Model Engineering Supply.

All for this post, standby for post 3!

Enjoy!

Mike
MIke
Wichita, KS, USA

Offline b.lindsey

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Re: Pottyengineering Horizontal Mill Engine - Imperial - Mike's 3rd Engine
« Reply #43 on: November 25, 2018, 12:13:02 AM »
Very nice work Mike. Looking forward to the third post now too.

Bill

Offline mikehinz

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Re: Pottyengineering Horizontal Mill Engine - Imperial - Mike's 3rd Engine
« Reply #44 on: November 25, 2018, 12:14:49 AM »
And finally the last post of today's work.  The dreaded cast iron flywheel! 

First of all, thanks again for all the great advise given earlier! 

I chose to follow Mr. S Hart's recommended work process, at least as best I was able to!

I mounted the casting in the 4 jaw with the jaws reversed.  I decided that the one area that would be impossible to machine was the ID of the flywheel between each spoke so I wanted to get that area to run as true as possible.  I got it close by eye and then tried a DTI just moving it in and out with the carriage.  That didn't work so well.  The casting is too rough.


Then I tried using a surface gage with the curved tip as a probe.  I set it on the carriage and moved it in out out between the spokes and just judged it by eye.  That seemed to work ok.


Closeup of how I used the surface gage pointer tip.


Pix after I faced off the outside of the rim and cleaned up most of the center hub.


Starting to cut the OD of the rim.  I set the lathe to turn at 260 rpm and was using a CCMG insert.  The casting cut very well, no hard spots and it didn't take all that much to clean it up.


Then I took a 3mm radius tool and started cleaning up the root of the hub.  This actually worked pretty well.  No chatter on the CI.


Then did the same cleanup on the inside of the rim.  I didn't try to get near the spoke webs as i figured disaster was sure to occur if I were to try that. 


Then I spot drilled the hub, drilled thru 19/64" and reamed to 5/16"   All with no cutting fluid and 260 rpm.


I was able to fit a piece of 5/16" drill rod by hand but it was quite tight so i think it turned out just right.


The 1/2 finished flywheel on the bench.


The unfinished side of the flywheel.


I made a mandrel out of a 4" piece of 5/16" drill rod.  i put a center hole in each end so i could turn it around as needed.  Shown is the mandrel inserted into the flywheel.  I cleaned both pieces with some spray brake cleaner and used some Loctite 603 retaining compound to secure the 2 pieces together.


And the last pix of the day shows the flywheel mounted in the lathe, ready for tomorrow's work.  I mounted one end with the 5C collet and the other end using a live center.  I want to let the Loctite cure for a full 24 hours before i try to finish it off.  I think the setup will be sufficient but I'll take light cuts and will see how it goes.  i did check and the flywheel runs quite true on the finished side. 


That's it for today!  Wish me luck for tomorrow's work on the flywheel! 

Enjoy!

Mike
MIke
Wichita, KS, USA