Time for a new Horizontal Hit and Miss engine

[Brian Rupnow]

Thank you for that information Jason. I have carbided a counterbore to hold a spring where the blue dashed lines are. it wasn't that hard a job. The big trick now will be to choose a spring of the right size and strength.---Brian

 

[Brian Rupnow]

Quick question--I want to do some rework on my camshaft which is made from 01 material, and is flame hardened and oil quenched. I think I can return it to a softer state by flame heating it to cherry red, then letting it air cool. I have to tap a couple of #4-40 holes in it, then harden it again. I think I can just reheat it to cherry red and oil quench it again to reharden it, but I haven't done that before.---Brian

 

[Nerd1000]

Quick question--I want to do some rework on my camshaft which is made from 01 material, and is flame hardened and oil quenched. I think I can return it to a softer state by flame heating it to cherry red, then letting it air cool. I have to tap a couple of #4-40 holes in it, then harden it again. I think I can just reheat it to cherry red and oil quench it again to reharden it, but I haven't done that before.---Brian

That should work, but you'll need to temper it again as well.

It's best to avoid repeated heat-quench cycles because they tend to remove the carbon from the upper layers of the steel, reducing the surface hardness.

 

[Sparky_SC]

a quick search found this recipe on a steel manufacturers site for annealing O1 steel. Sounds like the proposed torch method may still leave it quite hard.

Annealing​

Annealing must be performed after hot working and before re-hardening.


Heat at a rate not exceeding 400°F per hour (222°C per hour) to 1425 -1450°F (802-816°C), and hold at temperature for 1 hour per inch (25.4mm) of maximum thickness; 2 hours minimum. Then cool slowly with the furnace at a rate not exceeding 50°F per hour (28°C per hour) to 1000°F (538°C). Continue cooling to ambient temperature in the furnace or in air. The resultant hardness should be a maximum of 212 HBW.

 

[Charles Lamont]

If you have some vermiculite in your potting shed you could bury the red hot part in that, so that it cools more slowly.

 

[Gordon]

Quick question--I want to do some rework on my camshaft which is made from 01 material, and is flame hardened and oil quenched. I think I can return it to a softer state by flame heating it to cherry red, then letting it air cool. I have to tap a couple of #4-40 holes in it, then harden it again. I think I can just reheat it to cherry red and oil quench it again to reharden it, but I haven't done that before.---Brian

Put it in your kiln and let it cool in the kiln. That will make uniform heating.

 

[Brian Rupnow]

I just put the cam shaft in my vice and heated it to cherry red, and I'm leaving it to air cool. I don't have any vermiculite. ---I do have another unhardened piece of 01 steel, so if I need to I can make another camshaft. After this one cools, I will let you know how much success I had threading very small holes in it.

 

[Brian Rupnow]

And the story is---No, it didn't work for me. The part is still very hard. I could turn a bit off the o.d. with a carbide cutting tool, but no way was I going to be able to drill and tap it for #4-40 threads. That's okay. I have lots of unhardened 01 to make a new cam shaft, and I've learned something today.---Brian

 

[L98fiero]

I just put the cam shaft in my vice and heated it to cherry red, and I'm leaving it to air cool. I don't have any vermiculite. ---I do have another unhardened piece of 01 steel, so if I need to I can make another camshaft. After this one cools, I will let you know how much success I had threading very small holes in it.

DRY kitty litter/Floor Dry works for larger pieces pretty well, too, or put it in with another, larger piece beside the one you want annealed.

 

[Brian Rupnow]

No cat, so no kitty litter. I will remake the camshaft and cam, they are not complex shapes. If this had been a really complex part with a lot of hours in it, I would have taken it to one of the local machine shops and had the threads edm'd in. As it is, it will only take a couple of hours to remake the part.

 

[trlvn]

I just put the cam shaft in my vice and heated it to cherry red, and I'm leaving it to air cool. I don't have any vermiculite. ---I do have another unhardened piece of 01 steel, so if I need to I can make another camshaft. After this one cools, I will let you know how much success I had threading very small holes in it.

Annealing a hardened piece of O1 shouldn't be difficult. It needs to get slightly above critical temperature (non-magnetic) and stay there for a little while (minutes with a small piece like this). It probably cooled too rapidly in the air. Another old timers solution is to bury the hot piece in fireplace ashes while cooling. Even dry sand will work. Not wet sand--red hot metal plus moisture equals "A Bad Thing".

Craig

 

[Brian Rupnow]

Today is a "no work day". Both of our boys have a birthday in December, so today is family feast day with all of our kids, spouses, and grandchildren coming at noon for birthday celebrations. I am currently doing a bit of rework on the camshaft to get a better "hit and miss" situation going, on advice from Jason. This view with the camshaft removed shows the roller bearing that fits into a hole in the near sideplate to support the new camshaft.

 

[Brian Rupnow]

This is a cross section thru the governor shown in its "engaged" condition. A hit and miss governor should engage at about 500 rpm. engine speed. The strength of the governor spring should hold the governor in its "not engaged" position until the engine rpm reaches about 500 rpm, at which point the governor should engage and start the engine into its "miss" cycles. Since my governor is driven off the camshaft, then my governor should begin to engage at 1/2 that speed, so my governor should engage when it reaches 250 rpm. It is a lot of work to get at that governor spring to change it, so I will do a mock up on my milling machine which has an rpm readout on the quill, and drive the governor at 250 rpm. and use that as a basis for the governor return spring that I use.

 

[awake]

Asking out of ignorance ... would increasing the weights of the governers also slow down a hit-n-miss engine?

 

[Brian Rupnow]

So----It did take more than a "couple of hours", but I have a new camshaft and a new big collar where the swinging counterweights pivot from. All seems to be well, and I will be making my test tomorrow driving it with my milling machine to determine what strength of compression spring it needs . Andy--Increasing the weight of the governors make them swing out sooner due to centrifugal force, so yes, it would slow the engine down. The more you play with governors, the more you begin to see the interdependencies between governor weights, governor rpm, engine stall speed, engine recovery speed and governor return springs. I see that on the original Hercules engines that used this type of governor, the governor was driven from a small gear and spun much faster than it would if it had been ran directly of the cam gear like mine is. Tomorrow I will get to see if I can achieve the same results running of the cam gear but with a much lighter governor return spring.

 

[awake]

Ah, it just now clicked for me that you are running the governor on the cam shaft, not the main shaft. That surely makes it much more challenging to get the weights and springs and such set just right, since you're turning half-speed.

 

[Brian Rupnow]

Today we are going to build a test rig to test the optimum spring strength for my governor. The grey part will be made from aluminum with a 0.875" hole in it to match my camshaft diameter and the bottom of it will be held in my milling machine vice. The green part will be turned from a piece of aluminum and bolted to the face of the 60 tooth gear. A second pulley of the same diameter will be held in my milling chuck and a 0.1" neoprene drive belt will connect the two pulleys with a 1:1 ratio. Whatever rpm my spindle is turning, the governor will turn at the same rpm. I want to find a spring that lets the governor actuate at 250 rpm.

 

[Brian Rupnow]

This test was one of those things that worked good in theory.---In practice, not so much. The rubber o-ring drive belt kept stretching and slipping, and the camshaft kept finding tight spots, then loose spots in the aluminum bar which is supporting it. No good conclusion could be reached from this test, but I THINK that the spring I have in the governor right now is way too stiff. I had the mill rpm turned up to 500 rpm, but couldn't see any visible movement of the center pin in the governor, which is supposed to move at 250 rpm. Tomorrow I will repeat this test, but will couple the camshaft to my mill spindle with a short driveshaft with two universal joints that I built a few years ago, and a set of 90 degree bevel gears mounted in a carrier that I built a few years ago. Hopefully that will work better, as there is nothing to slip.

 

[Jasonb]

Why don't you pull the crankshaft gear off the engine and mount that on a stub held in the lathe. alter the height of your bracket so you can mount the governor on the cross slide as you have a read out on the lathe too.

 

[Brian Rupnow]

I thought of that Jason, but the rpm readout on my lathe doesn't work.