Flat belt circle mill drive ???

[backpacker]

I am still working on the assembly of my circle stud mill, using the 10hp, make and break engine.
Has anyone got suggestion(s) on a belt tension device? I plan to have the belt slack and slip
when not using the mill, as in starting/cool down periods. 
With approx a 15 to 20 ft spacing between driving and driven pulleys, i can assemble a flat pulley, 
tensioner, that either pushes down on top of the drive belt going to the blade arbor or pushes up on the return side of the belt .
would of liked to have a sliding engine type of tension device, but the weight is too much to have an easy moving unit.
tks for all suggestions.

[miro]

Longer  the belt, the better  at lest 20 ft between engine and driveshaft.
I think 10HP might be a bit weak - maybe OK for smaller logs . The engine will be all make, no break when cutting. Belt tensioners using a pulley usually don't work well, better to get te belt tensioned with engine position adjusters.
Sharp blades will save quite a bit of your limited HP

[captain_crunch]

Don't know how big your blade is but 10 hp ain't going far I run a 46" blade and it makes a 50 hp tractor grunt if I were to build another mill I would PTO power it that way you're mill power could be used for other things when you're not sawing newer tractors 🚜 have Independent PTO rope and a couple really small pulleys and you got whoa and go
Brian

[Ron Wenrich]

Rule of thumb - 5 hp/inch of wood.

[OldTractorMan]

Not sure what a "circle stud mill" is, but if it's a circular saw type blade I agree with captain-crunch, 10 HP sounds a bit weak. I ran a 54"  "Frick" left hand mill for years. I never used tensioners.  I changed the flat belt to PTO and never looked back.

[moodnacreek]

Use what you got but flat belts are only really good for certain situations like feed belts that have to slip all the time. A twisted belt is the worst, last resort only.  Today with imported shivs and vee belts it is much cheaper than when I started and flat belting is expensive.  The more power you can get on a sawmill the better, makes it run smooth.

[Al_Smith]

If "make and break" means an old oil field pumping engine with a big flywheel you'd be surprised of how much running torque they have .You'd also be surprised how much they weigh,a bunch  .The way they rated them years ago was different than today . It probably wouldn't be my choice but good luck .

[Gearbox]

I ran a 50 inch saw with a 3 71 Detroit turned to 100 horse that would bury the saw at full stick if I could keep the belt hooked up . I also ran the same mill with a S C Case it would saw but not much . Like the guy said that had a 6 71 on his mill there ain't nothing better than brute horsepower .

[ButchC]

If "make and break" means an old oil field pumping engine with a big flywheel you'd be surprised of how much running torque they have .You'd also be surprised how much they weigh,a bunch  .The way they rated them years ago was different than today . It probably wouldn't be my choice but good luck .

In some circles make and break is used to describe what most call a hit-miss engine.
I am not familiar with the terminology circle stud mill but agree that 10HP is pretty weak if your going to cut much wood.

[backpacker]

Morning gentlemen, Yep the hp available is not the greatest, and to explain a bit of "why" i want
to do so...The engine [Acadia Gas Engine], was used on a good older friends mill that he  used to cut lobster trap material.
I retrieved it but the mill was a bit toooooo homemade and scary to use, so i picked up a proper old 8ft stud mill,to go with it.
Its more of a hobby, memories, display, and a place/item to collect stories/tales/lies from the locals..
Not looking to go into mass production with it, i have the band-saw mill for that.
Originally the owner would start the engine and then hand feed the belt onto the engine pulley, all in the name of that's how we always did it......and guide it off when finished with a piece of wood, which is nicely smoothed and shaped over the years to be just the right piece of wood for the job.
I have looked at the sliding engine plan, but the weight and thumping of the unit would be a problem? 
Lots of time yet to think of a design, and if one doesn't work, try the next one..good to learn stuff.
Tks for the reply's 

[moodnacreek]

Putting a belt on running is something you don't want to get caught up in. The right way to do it is with double idlers. Thats not going to happen. If the belt is not to heavy it can be held and put on with 2 sticks. Otherwise you need to rig up some way so you keep your hands away. If you ever get caught by a running belt it will happen very fast . Also don't think gloves will protect you as they only make it worse [more traction and less warning]

[Magicman]

This one is set up at a customer's location for display.  You can see my sawmill and logs at 1:36 in the video.
DSCN2191 - YouTube

[Al_Smith]

Try as I might I can't find any conversion charts showing HP ratings on these antiques to modern examples .I will say a buddy has either a 10 or 15 HP rated Cooper-Bessemer he found in an abandoned pumping shed in Michigan.It's trailer mounted for display and uses a 5 HP for a pony motor to start it .Under a load like a "baker fan" it hits on every revolution and will spin that fan nearly as fast I could with a 34 HP John-Deere model 70 gasser .That thing has a piston the size of a coffee can with a scavenging air cylinder as well as the larger power cylinder  .I think that example is grossly under rated .

[backpacker]

Have no fear of me putting a belt on a running engine.....the old guy also did the old trick on putting his foot on a wheel arm to use his weight to turn it over.....bad enough just pulling it over with the flywheel itself by hand.
We'll keep our sticks on the ice and stay safe.