Building a model Drag Saw

[Brian Rupnow]

This morning I even found room for a gas tank. I also changed the two members that reach from the engine up to the log. I originally had them as 1/2" round rod, but all of the drag saw videos show them as being rectangular wood. I'm getting close to the point where I start cutting metal.

[Brian Rupnow]

Today I finished most of the detail drawings and machined the gear half of the dog clutch. It may prove interesting to make the other half.

[Brian Rupnow]

Something in my black old heart tells me that both parts of the dog clutch should be hardened, then "drawn back" to a point where they are tough but not brittle. My heat treat capabilities are limited to oxy-acetylene torch and my wifes kitchen oven. I already had the gear, made from 1018 mild steel so can't heat treat it, but I am going to machine the drive dog tomorrow, and it just happens that I do have a piece of o1 material the right diameter. I will machine it to size, heat it to cherry red with my torch, then drop it into a container of oil. Then 2 hours in my good wifes kitchen oven at 350 degrees F for two hours.

[zeeprogrammer]

I've been watching. 

A drag saw (not that I knew about them before) is a wonderful model of times past.

[Johnmcc69]

 
 
Very cool Brian.

 John

[Jasonb]

Brian, you could case harden the mild steel gear which will give a hard wear surface but the core will remain soft.

[Brian Rupnow]

Jason--I would like to do that, but I would have to send it out and have it done somewhere, as I have neither casenite nor a heat treat oven.----Brian

[Jasonb]

I do it with my propane torch, your Oxy one would do it too. There are some home brew mixtures if you don't have the powder using things like leather and bone.

As you are only heating to red, dipping in the powder and then quenching the heating is no different to how you harden your O1 but as it needs no tempering afterwards you don't even need to bother the wife about using here oven

[Brian Rupnow]

Hark Hark--The dogs bark!!! Dog clutch is finished and will engage and disengage as I had hoped. A lot of fussy set-up, but turned out great. Pictures show it engaged and disengaged.

[Brian Rupnow]

All the gears that will be used in the drag-saw are finished. The largest and smallest were "repurposed" from the walking beam project. The center gear was just finished 15 minutes ago, and I'm done for the day. My back is killing me and I have to go across town and pick up some aluminum from my supplier.

[Craig DeShong]

Interesting project Brian. 

I've seen a few of these in full size.  The model will be interesting.

[Brian Rupnow]

Hi Craig--I haven't seen one before either, only YouTube videos. I did see one at a steam show in Milton last weekend, but it was a different style than the one I'm making, and it wasn't operating. I have just about ran out of ideas for things to run with my engines, so I welcome a new project.---Brian

[crueby]

This build has inspired me to finally go back and figure out how the valving works on the Ransome Tree Feller, which is a simaler setup to this but steam powered - had never been able to figure out the valving till now. At some point I will model it up in Fusion as a 3D model from the patent drawings (probably during some cold snowy week this winter).

For now, really enjoying this build!
 

[Brian Rupnow]

Hi Chris--Thanks for your interest. I follow your thread every day. Now that I have the basics of the dog clutch finished and the gears cut, my next step will be to make the two plates which support the engine and the shaft for the gears. I want to start the engine and see how it handles the load of the gears alone, although I think it shouldn't have a problem.---Brian

[Brian Rupnow]

So far today, it has been "work like Hell and not accomplish much" kind of a day. I did drill and ream holes in a piece of scrap at the calculated gear centers, and all seems to be fine. Gears mesh with no binding. In the picture they are running in the mill with lots of oil on them. I will let them run for 15 minutes or so before tearing the set-up down. Now, I have a calculated number for the sprocket centers, and will test the chain and sprockets the same way, after I have shortened the chain to the appropriate number of links.