Author Topic: Tangler's Air Cooled Farm Boy  (Read 3351 times)

Offline tangler

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Re: Tangler's Air Cooled Farm Boy
« Reply #15 on: July 31, 2019, 10:42:49 PM »
Of course, It didn't go quite that smoothly.



On the third attempt I forgot to allow for the cutter width on my drawing and made the big end too narrow  >:(  C'est la vie

The big end needs a 1/16" hole to allow oil to get to the bearing.  This little gizmo is very useful on my mill since have only a rising knee and no quill



The big end bearing was cut from an over size lump of bronze and each side faced



The 2 halves were then joined together with solder paste



The lump was the rotated in the 3 jaw chuck until the centre was on the split line



The bearing was drilled and reamed before mounting on a mandrel.  I turned the smaller diameter with a 1/16" HSS parting tool.



The bearing needs a pair of semi circular grooves 180 degrees apart to allow clearance (and anti-rotation location) for the studs holding the bearing cap.  There also needs to be a 1/16" hole in the bearing to allow penetration of oil at 90 degrees.  I mounted the bearing, still on its mandrel on the dividing head on the mill and then carefully located the split in the bearing on the spindle centre.  I seem to have forgotten to take any pictures of the actual machining - sorry.



It wasn't, of course, my first attempt so here is a picture of one I made earlier but in the wrong orientation



Cheers for now,
Rod









Offline Craig DeShong

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Re: Tangler's Air Cooled Farm Boy
« Reply #16 on: July 31, 2019, 11:41:03 PM »
Hi Rod.  Just picked up on this build.  I have to say that CNC machining must present it’s own set of problems.  Being a programmer for an occupation you’d think I would have gravitated to this type of machining but I guess i’m just old school.  :old:

I also like that you’re showing your attempts.  We’re not infalable ( at least not me) and I appreciate you honesty in showing your previous attempts.  I think it helps the newer guys in seeing that none of us are perfect. 

Watching this build with interest.  :popcorn: :popcorn: :popcorn:
Craig

Offline tangler

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Re: Tangler's Air Cooled Farm Boy
« Reply #17 on: August 01, 2019, 08:06:00 PM »
Craig,

Thanks for the comments.  It's nice to know that someone is looking in  :)

I wasn't entirely idle during the period that I have been wrestling with Fusion 360, although we did have a nice holiday on The Isle of Mull



I've made the crankshaft by fabricating from ground silver steel (drill rod) and Bright Mild steel for the webs.  I drilled and reamed the webs on the mill to get good location using the DRO



I put an accurate centre into each arm of the shaft for use later



The crankshaft was then assembled using Loctite retainer. A couple of Jo Blocks were used to keep the spacing correct.



After a couple of days to let the Loctite cure I drilled and reamed for taper pins





I then released the piece of crankshaft between the webs



Again, I've tried to get rid of the "made from barstock" look by rounding the ends of the crankwebs.  I used half of a cylinder as a filing guide for the crankshaft pin



The other end of the webs was much easier using my toolpost mill and the GHT HDA



There are still some keyways but the bulk is done



It only needed one attempt - things are looking up  ;D

Thanks for looking,

Rod





Offline Admiral_dk

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Re: Tangler's Air Cooled Farm Boy
« Reply #18 on: August 01, 2019, 10:02:37 PM »
There are more looking in / following your build - though admittedly not saying much so far.

I can fully relate to certain CNC errors as it took me two hours today, to get a simple rectangular "slot" in a piece of plywood right - it was a "jig" to hold the boxes I needed to "drill" for some prototypes at work  :facepalm:
« Last Edit: August 02, 2019, 10:55:40 AM by Admiral_dk »

Offline Roger B

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Re: Tangler's Air Cooled Farm Boy
« Reply #19 on: August 02, 2019, 08:00:01 AM »
Glad to see you back on this one  :ThumbsUp:  :ThumbsUp: I hope you can sort out your CNC problems  :killcomputer:
Best regards

Roger

Offline Johnmcc69

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Re: Tangler's Air Cooled Farm Boy
« Reply #20 on: August 02, 2019, 03:19:08 PM »
There are more looking in / following your build - though admittedly not saying much so far.
:popcorn: :ThumbsUp:
 john

Offline rudydubya

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Re: Tangler's Air Cooled Farm Boy
« Reply #21 on: August 02, 2019, 10:11:04 PM »
There are more looking in / following your build - though admittedly not saying much so far.

Indeed there are, Rod.  Following along quietly.

Regards,
Rudy

Offline tangler

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Re: Tangler's Air Cooled Farm Boy
« Reply #22 on: August 03, 2019, 06:35:30 PM »
Thanks for the love guys  :)

The next job is to bore the holes in the body for the main bearings.  To do that I need to make the bearing caps so it was time to glue the 2 halves of the body together with JB Weld.  I did that yesterday so today I took a skim across the bottom



I was quite leased with that - I could feel it sticking to the surface plate.  The caps are just some bits of ally which I squared up in the mill and used the DRO to get the hole spacing which I've drilled for 5mm tapping



The caps were then clamped to the body and drilled through



I've come to really like these spiral flute taps, almost as much as the tea fairy who appeared at an opportune moment





The caps were fastened in place with some temporary cap head screws.  The bearing caps are taller than they need to be at the moment and I'm thinking that I will give them some fancier shape rather than leaving them square.  The crankshaft needs to be nicely aligned with the cylinder so I clamped the body to an angle plate and then squared it up in both the Y and Z directions



The distance from the centre line of the crankshaft to the front face of the body is also reasonably critical so I Used an edge finder against the front face and used the DRO to find the correct distance to spot on the split line of the caps and then drilled through the upper cap 1/4"



I then used a long centre drill to spot the lower cap



A succession of holes where then drilled using a stub drill for the upper hole and a jobber for the lower where I had the right drills





The last drill was 12mm of which I only had a jobber length.  I had now run out of headroom using the ER chuck but was able to use a one of the Myford patent collets which are 2mt with a securing nose piece which screws on to the nose of my mill.  I've done a bit of buying and selling part sets of these collets on ebay to acquire some useful sizes in both metric and imperial



The final operation was to ream using a 1/2" machine reamer which, oddly, has a 10mm shank



Cheers,

Rod



Offline Jasonb

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Re: Tangler's Air Cooled Farm Boy
« Reply #23 on: August 04, 2019, 01:19:29 PM »
It's progressing well Rod. The bearing caps will look nicer with a bit of shape to them rather than the boxy drawing shape.

Keep up with the Fusion I'm slowly getting the hang of it and like you my spiral flute taps are the ones I reach for first especially now that Uncle Ketan has topped up the sizes I already had together with a set of spiral point ones.

Offline tangler

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Re: Tangler's Air Cooled Farm Boy
« Reply #24 on: August 04, 2019, 04:59:27 PM »
Thanks Jason, I'll give it some more thought.

I had an hour to make the main bearings this morning, They are simple turning jobs from bronze



The overall shape was parted off and the reversed into a 1/2" collet before drilling and reaming



My 3/8 reamer is of unknown tolerance but I know from experience that it is too tight for a running fit in bronze so I have made a simple D bit from 3/8" silver steel that works very nicely to enlarge the hole. That hardened end has swollen with the heat treatment and measures 0.376" - the untreated bit is a true 0.375



This is how the bits go together



Thanks for stopping by,

Rod


Offline tangler

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Re: Tangler's Air Cooled Farm Boy
« Reply #25 on: August 06, 2019, 09:45:54 PM »
I've made a start on the flywheels today.  I  bought these a few years ago from College Engineering Supply.  They were being sold off at £25 for the pair and were actually the genesis of the idea of making the Farm Boy.  They are not particularly good quality, I think they were essentially seconds.  They're good enough - nothing that JB Weld can't fix  8)

I mounted them on a faceplate with some sacrificial pads behind the rim and then centered them as best I could on the inner rim which will not be machined



I turned the rim and sides and faced the central boss.  Then drilled and reamed the central hole for the crankshaft.



I then turned it around on the faceplate, centered it according to the rim and faced the other side



A little bit of novel excitement now.  I took advantage of a couple of recent discount offers from ARC and Machine Mart to buy a 2 and 3mm set of push broaches and a small arbor press.  The drawing calls for 1/8" key way but I think that 3mm will be fine.  I did need to make a new guide to suit the 3/8" hole in the flywheel.



And so I got to play with the press as well.  It all went very smoothly.



Rod



« Last Edit: August 07, 2019, 09:25:03 AM by tangler »

Offline Johnmcc69

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Re: Tangler's Air Cooled Farm Boy
« Reply #26 on: August 06, 2019, 10:16:36 PM »
Nice work Rod!
 Is the broach secured in the arbor press? I have a small press & have often thought about adding some sort of block or chuck to hold tools.

 John

Offline b.lindsey

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Re: Tangler's Air Cooled Farm Boy
« Reply #27 on: August 07, 2019, 02:33:59 PM »
Its beginning to look like an engine now Rod. Nice work on all the recent parts!!

Bill

Offline Don1966

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Re: Tangler's Air Cooled Farm Boy
« Reply #28 on: August 07, 2019, 03:01:45 PM »
Just finish catching up on your build Rod always great work and setups. What I am surprised about is you haven’t build the micrometer dial for the Mayford tailstock yet. ...... :praise2:


 :cheers:
Don

Offline tangler

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Re: Tangler's Air Cooled Farm Boy
« Reply #29 on: August 07, 2019, 03:54:15 PM »
Hi Chaps,

John,  The arbor press just has plain end.  I've only used it for the broaching and pressing in the bearing on the little end of the connecting rod.  I'm sure it could be modified if required.

Don,  I have been tempted. Gray, as usual, has designed a very elegant solution but I have been satisfied with my own fix for a few years now and it's dual reading   8) :



I've been doing some sums today.  Jerry's drawing calls for 48DP 72T and 36T gears to provide a half speed drive for the cam.  I have set of 0.5MOD gear cutters.  PCD of the 72 T gear is 1.5" which is 38.10mm.  PCD of 0.5MOD 76T gear is 38.0mm.  Good enough.  Jerry also calls for the larger gear to be made of brass or bronze with the smaller gear being steel.  Good engineering practice but surely not usual in full size engines.  Anyway, I haven't got a suitable bit of brass or bronze so both will be made from FC steel  :o

Cheers for now.