Elmer's 36 Reversing Wobbler - 2x - Imperial - Mike's 2nd engine

[mikehinz]

Today, I had another fairly long day in the shop.  i didn't get quite as much done as I'd hoped as there was a challenging (at least for me) setup involved.   In any case here's the pix and some explanation for each of them:

First up, truing up the flywheel so that it runs completely concentrically with the crank.  I hate wobble in flywheels!  Just before this shot, I'd taken a very light facing cut without the live center in place.  I didn't have to take off much, maybe .004 before that side was true.


This was the setup for facing the 'inside' of the flywheel.  This worked well as that's 1/2" drill rod for the crank being held in a 5C collet and supported with a live center at the other side.   It turned out that between the 2 faces, I only ended up taking about .008 to get the faces running true.  On the OD, I ended up taking about .030 off the diameter, but most of it wasn't wobble, it was mostly taking off the rust and rough finish on the material that I was using.


First pix of the completed crankshaft / flywheel / crank pin.  I don't have any pix of the fitment of the crank pin, but as with the crankshaft, i'd frozen the pin overnight and then applied Loctite 603 and pressed it in place quickly.  This took a bit more effort than the crankshaft but I managed it using my shop vise.  I was wishing for a hydraulic press!


Pix of the other side of the assembled flywheel.  Prior to taking it out of the lathe, I spent a bit of time with emery cloth and Scotbright trying to get a fairly good finish.  I oiled it up so hopefully it won't rust immediately. 


Now onto working on the remaining operations on the cylinder.  These pix are a bit out of order as I did the same setup on the face of the cylinder and for the bore.  Basically the same process. I indicated with a DTI on just inside a centerhole I'd put in while the block was in the mill.  I also checked if the face was running true using a dial indicator. 


and


Starting to turn the radius on the cylinder.  I think this is purely decorative, but I followed Elmer V's original intent.


Turning the smaller diameter using a 3mm carbide turn/groove tool.  This worked really well.  I'd turned down the rpm to about 260 and took fairly light cuts.  Very nice finish when it was done.


Going back and finishing off the larger diameter.  Using a carbide CCGT insert.  RPM was still 260 and cuts were light, about .015 on radius.  No issues during this operation.  Also, i took a very light skim cut on the cylinder face to make sure it was true and square.  It took no more than .002 or .003 to get it flat and square.


Drilled the pivot shaft hole, then threaded the bottom .3125 5/16-24.  First I used a plug tap, then followed that with a bottoming tap The first .3125 was drilled and reamed to .376 to make sure the pivot shaft is well-aligned, hopefully!


This pix shows reaming the first .3125 of the hole to .376.  Ran the lathe slow and the reaming seemed to go fine.


Trial fit of the pivot shaft into the cylinder.  Success!


And finally, the cylinder is back on the bench, ready to reinstalled in the lathe tomorrow to start drilling and boring for the actual cylinder bore.


All for today!  I think I'll have some time tomorrow afternoon to work on this again.  I'd love to be able to complete the cylinder and get a good start in make all the holes in the column.

FYI.

Mike.

[mikehinz]

All, I have a quick technique question:

What's the best way to center rectangular pieces with off-center hole in a 4 jaw chuck?  As above, what i attempted was to put in center holes at the required locations using the mill and then using a DTI, make that center hole run true.  This seems very slow to me.  I'm sure some of it was lack of familiarity with the process but using a DTI in a very small hole like that is tedious.  It's hard to get it close to on axis and generally a pain!   

So, any input regarding a better process is greatly fully appreciated!

Thanks.

Mike.

[crueby]

I normally use a dti on the sides of the part, make the first two opposing sides have the same reading, then the other two.

[zeeprogrammer]

Sorry Mike. I can only see the last two pictures.
I hope this isn't too frustrating...and I'm beginning to question my browser but I haven't had this issue before.

[propforward]

I can only see the last two pictures also. Great work in them though.

[gary.a.ayres]

Mike - same here - last two pictures only.

The cylinder looks great though!

gary

[Jo]

Hi Mike,

What's the best way to center rectangular pieces with off-center hole in a 4 jaw chuck?  As above, what i attempted was to put in center holes at the required locations using the mill and then using a DTI, make that center hole run true.  This seems very slow to me.  I'm sure some of it was lack of familiarity with the process but using a DTI in a very small hole like that is tedious.  It's hard to get it close to on axis and generally a pain!   

If the item was solid to start I would have marked it out and only centre popped the hole position then used a centre in the tailstock to hold it against something parallel while mounting it in the four jaw.

If you are talking about your bearing and lets say there is a rough hole already in there but possibly out of line I would start by marking the horizontal and vertical centre line of the hole I intended on boring out. Making sure the item is square in the chuck - centre those lines on the two opposite jaws of the chuck. Always worth checking with a square and a Vernier calliper to check it looks right.  Depending on how much metal has to come off you could adjust the location after the first cut.

Better still use a jig to mount the bearing on and then you will get the centre on the second bearing in exactly the same place

Jo

[mikehinz]

Mike - same here - last two pictures only.

The cylinder looks great though!

gary

Ok, I've redone all the links one more time, making double sure that I'm using the pix from my shared album.  What's driving me crazy is that everything looks good from my side when i check using a different computer.  It might be an account permissions thing where somehow my credentials are cached on the various computers I use even though i'm trying to use different accounts to check. 

If this doesn't work I may go for attachments directly to the email.  That way the pix are stored on the forum, but they are not inline with the text making understanding the workflow a bit more difficult. 

In any case, let me know if these pix are all now visible.

Again, sorry for the horrible posting attempts from me!

Mike

[zeeprogrammer]

Yep. All pictures there and they look great! 

[mikehinz]

Yep. All pictures there and they look great! 

Thanks for confirming!  I wish I knew what the exact difference was so that i could do it the same way each time. 

I'll most likely have a new batch this evening so I'll see if I can do this twice in a row successfully!

Mike.

[mklotz]

All, I have a quick technique question:

What's the best way to center rectangular pieces with off-center hole in a 4 jaw chuck?  As above, what i attempted was to put in center holes at the required locations using the mill and then using a DTI, make that center hole run true.  This seems very slow to me.  I'm sure some of it was lack of familiarity with the process but using a DTI in a very small hole like that is tedious.  It's hard to get it close to on axis and generally a pain!   

So, any input regarding a better process is greatly fully appreciated!

The method that works best for me is the use of what machinists term a "pump center".

Picture a rod with a male 60 deg point on one end and a female 60 deg recess on the other end.  The male end goes into the hole to be centered in the 4jaw and the female hole end is supported by a tailstock center.

As the 4J is rotated, the end of the rod near the part will describe a circle the radius of which is the offset of the hole from the lathe spindle axis.  A DI held in the tool post is used to track this motion of the rod.

Using the DI as an indicator, the 4J is adjusted until the DI shows no movement.  At that point the hole is centered.

If you're not comfortable with the 4J, you might want to read my treatise on centering work in it...

http://www.homemadetools.net/forum/centering-work-four-jaw-chuck-27241

[gary.a.ayres]

Looking good now...

gary

[mikehinz]

The method that works best for me is the use of what machinists term a "pump center".

Marv, that's exactly the information I was looking for!  I can center round stock up in a 4 jaw just fine, but the rectangular stock with a hole that needed to be offset from center was difficult for me.  The way I did it, as shown in my pix, using a DTI on the inside of a center-hole is tedious.  The 'pump center' will be much, much easier for me I'm sure. 

BTW, I did read your article on center in a 4 jaw and it's very good.

Again, thanks!

Mike.

[mikehinz]

Today's work.  Finishing the cylinder, successfully I think!

In yesterday's episode, we had a cylinder on the bench without a cylinder bore.  And here we start.  After reinstalling the cylinder in the 4 jaw and recentering it as per yesterday's process, drilling the bore commenced.  There was an existing 1/4" hole done on the mill, so I first went thru with a 1/2" bit and then with the 7/8" shown in the pix.  260 rpm.


Action shot of very even chips coming off both flutes on the drill.


Then commencing the boring operation.  That's a Sandvik bar with CCGT type inserts.  Very sharp for use on AL  Bumped up the rpm to 520.  The initial passes were .040 on the radius and then a couple of light passes of a few thousands to finish.  No issues with chatter.


Here's  pix of the overall setup.  8" 4 jaw chuck with homemade AL protectors on the jaws, AXA tool post and boring bar holder.  Sandvik insert type bar, Traveldial, and Unist MQL lubricator. 


Closeup pix of the cylinder very near the final ID.  Just wanted to show the detail of the setup.


The finished item pix 1.


The finished cylinder pix 2.


And finally the last pix o' the day.  I wanted to stay about .001 under size so to leave just a bit in case I have to lap or hone.  I got close enough for me!


I must say, I was quite thrilled to get this item done!  There were a number of operations that I'd not done yet so I was nervous during the entire operation!  Tomorrow I'll move back to the mill to drill all the holes for the air passages and drill and bore the large holes for the crank bearing housing and pivot shaft housing.  Should go ok, I think, but 2 of the holes require a #21 drill to 2.4" deep.  Wish me luck!

FYI.

Mike.

PS.  One quick question on the cylinder bore.  I achieved a pretty good finish on the cylinder bore ID just using the boring bar with a good sharp insert.  Does anyone think that there's a need to hone or lap that bore?  I have a small brake cylinder hone or I could purchase or make a lap.  So, is further finishing on the bore necessary and if so, would sort of operation should I try, lapping or honing?  I've decided to try a Noryl piston closely fitted.  As a backup to that, I also some cast iron bar and some SAE 660 bronze that I could try.  I'm also planning to just try a close fit.  If that fails, I'll cut an oring grove and fit a silicon or viton oring.  Thanks in advance for any help on this!

[Kim]

I'm sure that more experienced people will reply to you on this, but your finish looks pretty good on that bore.  Not sure you'd get a lot out of lapping it for an air or steam powered engine.  I see people doing IC and especially diesel engines doing a lot of lapping, so it must be more important there.  But I've not done any IC engines.  I have used a hone on a bore one time when the finish was really bad - that was back when I didn't have a boring head (didn't even know what one was) and I used a drill to make the cylinder.  The finish wasn't very good at all, and I used a little brake cylinder hone to clean it up.  That engine runs fine (though it does leak a little air, you can run it on breath power, so it can't be TOO bad, right? )

Kim