Fairbanks 80HP 3 Cylinder Model

[kadora]

CHUCK
Special vise is excellent idea i have to do one for my needs too.
Juraj

 

[cfellows]

Is the side milling fixture a vise jaw with a clamp on top? I might have mounted the rods through the holes with tight-fitting bolts, but I love your solution.

No, the side milling fixture is just made up from some scrap pieces of hot rolled steel.

Thanks, Barry, Thanks Juraj. I can post some additional pictures and dimensions if anybody is interested.

After a couple of days of mulling things over (and catching up on yard work :cussing, I decided to make the cam from solid.

I lined up the block on my lathe carriage and clamped it in place so I could enlarge the camshaft bore to 5/16".

The boring job went well and after reaming, a 5/16" drill rod fits through with no slop. The aligment is off about .015" from one end to the other, but it's not really noticeable and I can live with it.

Here I've got the cam blank mounted in the lathe and am in the process of turning down the diameter between the journals and the lobes to .150".

And here's a shot of the blank with all the turning done.

And the camshaft blank shown in the engine.

I left the cam lobes about .25" wide and while I want them to look beefy, I think I'll narrow them down some till I find a width that looks suitable.

Now to figure out a cam grinding fixture. I don't want something that will grind every cam I every build from now on, but I do want something that will give me a pretty accurate profile and finish without putting a whole lot of work into it.

Chuck

 

[kadora]

Chuck more pictures please.
I am pretty curious how you design cam grinding fixture.
Juraj

 

[cfellows]

I have he beginnings of a plan to cut the profiles on the valves. I'm going to rough them out using an end mill then smooth them up on a grinder.
Here is the jig I fabricated to hold the cam while I'm working on it.

I can turn the nylon bolts to adjust the tension on the camshaft making it turn easy, not so easy, or not at all. Next, I'll fabricate an indexing mechanism to adjust the angles on the cam lobes, probably a worm gear against the cam gear.

Chuck

 

[kilocharlie]

It looks like you could slap a degree wheel on the end of your fixture and pre-cut the cam very, very close before final grinding.

The only cam grinding machine that I have seen had the grinding wheel on an arm not unlike a chop saw and was geared to the lead screw.

 

[cfellows]

Think I'm about ready to start cutting the cam profiles. I finished the attachment and have it set up in the mill.

Chuck

 

[cfellows]

Moving right along, I screwed up my courage and tackled the cam this evening. I mounted the fixture in my milling vise and used a 1/4" carbide cutter (with some broken teeth it turns out). I made 3 passes taking .020" per pass to create the flat on one side of the first cam lobe.

Then, leaving the tool height where it was, I repeatedly turned the worm wheel crank one turn and made a pass with the end mill. I repeated this 25 times around the blank until I had the lobe point formed.

Then I turned the worm crank until the cam as position back to the start of the first lobe.

Then I cranked the blank 120 degrees and moved to the next lobe where I repeated the steps for the first lobe.

After I finished the third cam lobe, I removed the cam from the fixture and dressed it up with a needle file followed by a touch up with 400 grid emery cloth. And here's the result.

I'm definitely in the home stretch now. My scale model nuts and hex rod arrived from American Model Engineering Supply today. So tomorrow I expect I'll be back doing some drilling and tapping.

Chuck

 

[aonemarine]

Nice job on the cam! This is something I still need to to put some thought into making. I have some kind of indexing attachment for something that is very similar to what you have constructed. Just need to give it a whirl and test it out.
Chuck, you make it look too easy.

 

[Niceonetidy]

Chuck,

That is a really neat setup, the cam blank is self supporting too, very good idea,

Thanks for sharing,

Colin

Moving right along, I screwed up my courage and tackled the cam this evening. I mounted the fixture in my milling vise and used a 1/4" carbide cutter (with some broken teeth it turns out). I made 3 passes taking .020" per pass to create the flat on one side of the first cam lobe.

Then, leaving the tool height where it was, I repeatedly turned the worm wheel crank one turn and made a pass with the end mill. I repeated this 25 times around the blank until I had the lobe point formed.

Then I turned the worm crank until the cam as position back to the start of the first lobe.

Then I cranked the blank 120 degrees and moved to the next lobe where I repeated the steps for the first lobe.

After I finished the third cam lobe, I removed the cam from the fixture and dressed it up with a needle file followed by a touch up with 400 grid emery cloth. And here's the result.

I'm definitely in the home stretch now. My scale model nuts and hex rod arrived from American Model Engineering Supply today. So tomorrow I expect I'll be back doing some drilling and tapping.

Chuck

 

[deverett]

Bit late now, Chuck, on your excellent camshaft making, but Steve Huck also described the cutting of cams for his small V-8 with a grinding fixture.

However for others... Have a look at http://www.homemodelenginemachinist.com/f31/small-v8-8892/index74.html#post139850 reply 734

Dave
The Emerald Isle

 

[kadora]

Thanks Chuck for pictures of cam fixture.
Really professional job.
I have built this simple fixture but producing a camshaft
is time consuming .
Juraj

 

[cfellows]

Thanks for the comments, guys. Always appreciated.

I'm starting on what is hopefully the final "hard" piece(s), the rocker arm stands. There isn't much room, only about .160" between the top of the valve cage and the outside edge of the head. To maximize the thickness of the stand, I wanted to make it curved to match the profile of the head. So, I started with a piece of 1.25" 12L14 steel in the lathe. Also, the pivot of the rocker arm will be right over the edge of the valve cage, so the top of the stand will have to be offset inward from the base.

The plan is to make 4 stands (1 extra) from the perimeter of the rod. I'm starting by boring out the center. In the next photo, I've finished boring out the center. The smaller diameter at the bottom of the bore will form the offset on the top of the stand.

I'm now laying out the center the outside lines of each stand. In this photo I'm doing two of the stands.

Next I stand the vice on end to rotate the bar 90 degrees so I can lay out the other two stands.

Now I've got the bar mounted in the 4 jaw chuck and my rotary table which I have standing vertically.

Using a 1/4" end mill I'm milling out the waste on each side of the stand. I'll first mill all the left sides, rotating the rotary table 90 degrees for each one, then move the end mill to the other side and mill out the right side of all 4 stands.

After cutting out all the edges, I went back cut an inset on each side of each stand so the bottom of the stand will flare out 1/32"

Here you can see the profile of the stands.

Now I'm milling the slot at the top of each stand that will hold the rocker arm.

Gotta run out now and have some dinner with my honey, but I may get back to these later this evening. Next I'll drill the cross hole that holds pivot pin for the rocker arm.

Chuck

 

[stevehuckss396]

genius! Great idea!

 

[cfellows]

genius! Great idea!

Thanks for the high praise. Probably not deserved, but certainly appreciated!

Here's picture of the stands mounted on the heads. The bad news is that I had to use socket head cap screws. The good news is that the are pretty well hidden, recessed in the middle of the rocker arm opening.

They look a little bit blocky to me and I may try to slim them down some.

Chuck

 

[cfellows]

Not a very exciting day in the shop today. Still these things need to be done for the engine to run.

I made the valve keeper washers and fitted the springs to the valves. So the valve assemblies are done. I also made the exhaust manifold fittings and milled the flats for them in the heads.

Chuck

 

[cfellows]

Another brief update for today. I started on the rocker arms. I'm making them a little more complicated that originally intended. I think the results will be worth it.

I started with a piece of 3/16" thick cold rolled steel. I cut the width down to .8". The length is much longer than needed, but it's more about having a piece that's big enough to hold in the vise and other fixturing setups.

I've clamped the piece in my small horizontal vice which in turn is clamped in my milling vice so I can use a 3/32" clitting saw to put a groove in the sides.

Here I've turned the piece around to mill a slot in the other side. I've also put a piece of 3/32" drill rod in the finished slot so it won't be crushed shut by the holding vise.

And the piece with the slots finished. I made them a little deeper than I needed to, a case of the journey going so well, I lost sight of the destination! :

I've changed setups here and milling the waist that will be on each side of the rocker arms.

Here's the piece with the waist and slots finished. Next I'll need to part off the individual rocker arms and drill the cross holes.

Chuck

 

[jwcnc1911]

Very nice cam fixture Chuck! Is that a "standard" or you have to make one for every cam? I am definitely going to make something like this in the future. How are you clocking the cam? Counting revs on the handle and knowing the gear pitch? That is quite fascinating.

 

[Niceonetidy]

Chuck,

That is some great tooling you're making here. and the engine of course.

Look forward to more,

Thanks

Colin

Another brief update for today. I started on the rocker arms. I'm making them a little more complicated that originally intended. I think the results will be worth it.

I started with a piece of 3/16" thick cold rolled steel. I cut the width down to .8". The length is much longer than needed, but it's more about having a piece that's big enough to hold in the vise and other fixturing setups.

I've clamped the piece in my small horizontal vice which in turn is clamped in my milling vice so I can use a 3/32" clitting saw to put a groove in the sides.

Here I've turned the piece around to mill a slot in the other side. I've also put a piece of 3/32" drill rod in the finished slot so it won't be crushed shut by the holding vise.

And the piece with the slots finished. I made them a little deeper than I needed to, a case of the journey going so well, I lost sight of the destination! :

I've changed setups here and milling the waist that will be on each side of the rocker arms.

Here's the piece with the waist and slots finished. Next I'll need to part off the individual rocker arms and drill the cross holes.

Chuck

 

[cfellows]

Very nice cam fixture Chuck! Is that a "standard" or you have to make one for every cam? I am definitely going to make something like this in the future. How are you clocking the cam? Counting revs on the handle and knowing the gear pitch? That is quite fascinating.

Thanks, JW, this is the first one I've made and I used the cam and the timing gear from the engine that it's going into. I should be able reuse the same fixture with future cams. I may have to make or buy a worm gear for general purpose use.

Chuck

 

[cfellows]

I spent the day today working on the rocker arms. These fiddly little bits take a lot of time and the results are not as polished as I'd like.

Here are the rocker arms cut off from the one large piece I machined yesterday.

Here I'm parting off the 3/16" diameter rollers that will ride on the valve stems.

Here are the shaped and drilled rocker arms along with the rollers.

And here I've got the rollers installed in the rocker arms.

I cheated a little bit and used roll pins to secure the rollers.

Next I guess I'll tackle the pushrods and the adjusters at the top end for the valve clearance.

Chuck