Flathead hit and miss engine???

[Brian Rupnow]

Rdean---isn't is funny how another persons ideas can influence an entirely new train of thought. That happens to me a lot. I've always maintained that I can design anything, but the real trick is thinking of WHAT to design.---Brian

 

[Brian Rupnow]

So, half a day and a ton of swarf later, I have the inner hub of the flywheel half machined. Thats a lot of passes on a lathe that isn't happy with more than 0.015" depth of cut!!!

 

[Jasonb]

You should be able to take more than that off Brian, have you got it in low range?

 

[Brian Rupnow]

Yes, that is in low range cutting mild steel.

 

[Jasonb]

Mine is basically the same machine and will do 30-40thou on that sort of diameter steel, go about 450-500rpm with carbide

 

[Brian Rupnow]

I can only manage about 0.015" depth of cut. Of course that takes 0.030" off the diameter. Running at 700 rpm with carbide cutting tool.

 

[Brian Rupnow]

Now, if I just had 8 vanes in there, I'd have a finished flywheel/fan. I'm going to put the 8 slots into the center portion of the flywheel using a 1/8" slitting saw. I have to make a jig to hold things at 45 degrees for 8 successive cuts. There was probably more machining in this than there will be in the rest of the engine.

 

[Brian Rupnow]

Family (There are 14 of us now) are all coming for "family day" lunch. This morning I have sneaked away downstairs to add a bit to my engine design. My new flywheel is heavy. Too heavy to support with only one 1/2" bearing. I have added a bolt on box to the flywheel side of the engine and added a second ball bearing there to help support the flywheel load. I've also had to reduce the flywheel hub length to 0.8" because that is the length of the broaching guide that is supplied with my broaching kit for cutting keyways.

 

[Vietti]

Broaching guides are easily made.

 

[Brian Rupnow]

 

[awake]

Any thoughts on how you will index it?

 

[Brian Rupnow]

The yellow mark at the top of he red fixture is my index point. The actual part being milled will have a center mark every 45 degrees. Loosen the nut, then turn the part by hand, then tighten the nut. This is not a really critical part, so if I'm off by 1 degree either way it won't matter.

 

[Brian Rupnow]

I'm really pleased with the way this worked out.

 

[ShopShoe]

Brian,

I really like your fixture for slotting the flywhel hub.

--ShopShoe

 

[Nerd1000]

I can only manage about 0.015" depth of cut. Of course that takes 0.030" off the diameter. Running at 700 rpm with carbide cutting tool.

How fast are you feeding? A lathe that size should be able to handle more than that, unless your feed rate is way too high. For reference I run my Southbend clone at 50 thou DOC when roughing, and would usually feed somewhere around 6 thou per rev on steel. With carbide I usually just crank the spindle up as fast as the (1hp) motor can drive it in the cut I'm doing. I generally run out of torque before the carbide is even breaking a sweat.

If you're having lots of chatter problems it might be worth checking the spindle bearing preload, along with the fit and gib settings on all your slides etc.

 

[Brian Rupnow]

I'm not having problems with chatter. On any cuts in steel deeper than 0.015" the motor bogs down. I don't have a lot (any) experience with other lathes. This lathe has been like this since I bought it brand new. It's not really a problem unless I have a lot of hogging to do.

 

[Brian Rupnow]

Today is cylinder day at my house!!! That $50 piece of cast iron is being transformed from an ugly piece of cast iron into a beautiful (I hope) cylinder and cylinder head. The cylinder is almost finished turning--I have to turn it around in the chuck to get in with my parting off tool and finish tapering the fins. I didn't go with an aluminum cylinder with a cast iron liner----It is much easier to make the entire cylinder from cast iron. Hope to finish cylinder and cylinder head tomorrow.

 

[Brian Rupnow]

I can't get close enough to the chuck to use my parting off tool to cut the angle on some of the fins. Okay, time to do some thinking. The cylinder has a notch cut in the bottom for con rod clearance.---So---I'll fit the cylinder onto a longer 1" diameter steel rod and put a cross dowel thru the 1" steel rod and the notch to act as a drive dog. A drilled center in the end of the steel rod will let me support the outboard end with a live center in the tailstock. This will allow me to get in and finish off the fins.

 

[Jasonb]

Brian how are you holding the cylinder to the crankcase? looks like it will be difficult to get screws up from inside the case and you have nowhere fort a head and wrench from above.

Also on the previous drawing how will the crank be fitted?

 

[Brian Rupnow]

Jason--the bolts go up thru the crankcase from the bottom to screw into the cylinder.--Very long counterbores in the crankcase. The crank fits in thru the bearing hole.