1/4 Galloway crankshaft

[blockmanjohn]

Hi, I am currently building a 1/4 scale Galloway hit or miss engine with castings from Ministeam. I have made built up cranks for steam engines from drill rod and flat stock securing the webs and rods with loc tight and pins. These were very low power engines, and they worked very well.

My question is, could I use this system to build up the crank for the Galloway? The rods are 1/2 inch, and the rpm's would be low, but the power would be much higher than the steam engines.

I would like to use this method because of the fine finish on the drill rod which fits nicely into a 1/2" reamed bushing. Ministeam offers a lost wax, investment casting, steel blank, but I am not sure of being able to turn the rods to a fine enough finish. I'm not even sure how fine a finish would be needed. Grinding, maybe just emery paper?

I would really like to hear from any one with experience in this matter. Thanks in advance, John.

 

[kuhncw]

John,

My 1/4 scale Galloway crank is 609 Loctite and tapered pin construction, It has never given a problem. I had no luck pressing the joints together as I could not maintain alignment. I made the shaft to crank throw joints a light slip fit and made a fixture to keep the whole crank in alignment while the Loctite was curing. Once cured, I drilled and pinned the joints.

Please let us know how this works out for you.

Chuck

 

[blockmanjohn]

Chuck,

Thanks for the reply. I was hoping this had been done before with good results. Did you make the crank webs wider than the .625 specified on the prints?

 

[Jasonb]

On my 1/3 scale one I use precision ground mild steel which has the same finish as drill rod and is on size, silver soldered the joints and then pinned them as the kick when it hits is quite forceful.

 

[kuhncw]

Chuck,

Thanks for the reply. I was hoping this had been done before with good results. Did you make the crank webs wider than the .625 specified on the prints?

John,

Yes. My crank webs are 0.835 wide and 0.322 thick. Odd numbers, but that is the way it worked out. The 0.835 width looks good. I think my webs are 12L14 steel and I used 1045 TGP (turned ground polished) steel bar for the shafts. I used two tapered pins at each shaft to web joint and placed them so they went through the shaft and web at the OD of the shaft. Hopefully, that makes sense.

I also extended the cylinder liner all the way to the face of the cylinder block, to eliminate the step in the cylinder block bore. I did not use the liner casting supplied, but used cast iron bar. This means drilling the ignitor passage through the liner, but that is no problem. I have a bad habit of modifying these model engines.

Chuck