Renovating Circular saw mill / learning what i dont know

[Don P]

You all have more experience with this. I'm splitting hairs but if the engine is fixed it might be worth exploring. I've found with mine I don't want to be aligned dead straight with my pto shaft and mandrel. The pto shaft seems to bounce on the U joints less if I park the tractor just an inch or two off of straight in line. Mine has shear bolts and I buy them 10 or so at a time, a slip clutch would be a better setup there.

I plan to switch over to a stationary engine with pto and clutch, there is a 12" flat belt pulley on it and then a hub and 36" tire on the mandrel to do the step down and reversal. The slip and shaft side load will be adjusted coarse by sliding the engine and then fine with tire pressure. I'm hoping all that dials in within the stiffness of the mandrel and bearings. I'm wondering if the engine is better upstream or down of the mandrel or if it matters, I'm thinking lead "distortion" there more than anything.

[00frick]

You didn't say what brand it is or the size. A 371 G.M. will be fine on a smaller mill but yours sounds kind of fancy with air dogs. I probably would not try to push anything much bigger than a 48 inch saw. Maybe a little more. It is a common motor on older mills.  I have seen a number of responses as to the connection method. Which ever you use, you need a weak link. I prefer belts as I have had a wreck on of these and the belts worked. An exhaust extension on a Detroit is wonderful. Their sound alone will make you work. Engine position will depend on engine rotation (they were made both ways) and whether the mill is right or left handed. Regardless of all this, look at this thing and if you even start to think it needs a guard, build it. Think about the little things. Use your safety glasses, ear plugs, and hand gloves. These units can be very intimidating, as they should be. A big learning curve. My best to you and yours. Enjoy.   

[newoodguy78]

Any ideas?  Note the flat carbide we are pointing at.


Mike I'm not positive but I think those are edger blades 

[mike_belben]

 

Sorry for the hijack

[Haleiwa]

You all have more experience with this. I'm splitting hairs but if the engine is fixed it might be worth exploring. I've found with mine I don't want to be aligned dead straight with my pto shaft and mandrel. The pto shaft seems to bounce on the U joints less if I park the tractor just an inch or two off of straight in line. Mine has shear bolts and I buy them 10 or so at a time, a slip clutch would be a better setup there.

I plan to switch over to a stationary engine with pto and clutch, there is a 12" flat belt pulley on it and then a hub and 36" tire on the mandrel to do the step down and reversal. The slip and shaft side load will be adjusted coarse by sliding the engine and then fine with tire pressure. I'm hoping all that dials in within the stiffness of the mandrel and bearings. I'm wondering if the engine is better upstream or down of the mandrel or if it matters, I'm thinking lead "distortion" there more than anything.

That tells me that you have one or two worn bearings in the universal joints.  A properly aligned u joint should have no bounce, but if there is backlash in it, you will see a bounce, which is your shaft's way of telling you that it is waiting for the right time to fly apart.  The slight misalignment is simply creating tension on the driveline, which muffles the vibration.  Worn splines will do the same thing, but joints are the first place to look.  One other thing that will create chatter is if the yokes on either end of the shaft are oriented opposite each other, but most shafts nowadays have an asymmetry that will prevent that.

[moodnacreek]

2 things; The motor is mounted on the board end of a sawmill to sorta counter act the force of the saw in the log cutting. Drive shafts with U joints are not meant to run straight or said another way the joints should work. These rules are broken all the time.

[mike_belben]

Lay the shaft on a flat table and be sure the joints are in phase.. Meaning they both lay flat.  

I built a lotta driveshafts.  Its news to me that they cant run straight and im kinda not buyin it. They dont like being out of phase and they dont like unequal angles.. IE one yoke straight and one at 10*..  Thatll cause acceleration at one end and none at the other, the tube will not allow the two ends to experience difference acceleration rates and will wear out every part as quick as it can to let them become independant ends.

  Single cardan shafts like equal angle on each yoke.  If only one is gonna be straight then youll want a double cardan at the other end.  

[bandmiller2]

For your own sanity its good form to build a doghouse around the Detroit. Have enough doors for ventilation and in the winter direct the warm fan wash towards you and your off barer. Good place to lock up tools peaveys and cant hooks. Frank C.

[moodnacreek]

I ran a drive shaft straight for quit some and didn't have any trouble.  A very experienced  mechanic took the drive shaft [shafts] vibration out of my tandem axel, 2 transmission log truck. He showed me the formula and all the shafts had to be on angles.  It was said that the drive shafts are never to run straight.

[Don P]

My shaft has acted the same for over 20 years so I'm not thinking the u joints are about to crater. I've also heard the same thing about U joints needing to work, not saying that is right or wrong but I can wrap my head around it. The tractor is old enough to draw SS so the splines are certainly not great. The way I park the tractor it is in line with the mandrel but offset slightly, which means the angles are about the same. Now when I run the bush hog I have set it up with the tail high many times when I'm backing into roses and heavy brush... the pto shaft is running at many offsets and the u joint angles are dissimilar. I've worn out u joints but nothing like flying apart on it. From what I think I'm hearing Mike, you are saying with a single u joint on each end of the pto shaft the drive and driven shafts have to be parallel to avoid excessive wear. If you want to run them at anything other than parallel, as in turning a corner somewhat, you need a double U joint at one end?

[mike_belben]

[Cliff notes.  If you have 2 joints you need two equal bends.  If you have one end lined up straight and one end bent, you want a double cardan at the bend. ]

What you can get away with on a 540 rpm tractor and a shaft you do not sit ontop of is a lot different than a 5000+ rpm driveshaft on say a racecar, that has components strapping it essentially under your butt, especially if it is a 2 piece shaft with carrier bearing.  

Consider a single universal joint.  If you have zero angle on a joint then both halves will run at exactly the same speed across the joint, like a lovejoy jaw coupler.  The needle bearings wont move.  As you add angle to the joint, the joint caps and needle bearings get a lot more active, and there is a fraction of a second where the slaved side of the joint is moving faster than the master that is driving it.. This is the acceleration i was describing.  The more angle the more acceleration.  Now to cancel this out we need another joint at the other end to have an equal angle so it is also marching to the same beat at the same time.  With single cardan at each end you halve the total angle between the two joints so that the acceleration is even along the entire shaft.  Phasing joints is important so that the acceleration starts and ends at the same time for both joints, they are sync'd.  

When you use a double cardan shaft you have 3 joints. The solo universal has zero angle (shaft and yoke are inline) and the other end has two joints each sharing half the bend degree for the reason described above.  

In automotive applications, vibration can be from out of balance tires and shafts and so forth.  But if everything is truly zero balanced and there is still a bunch a shakin going on.. Its usually the driveline.  New joints, tight slip yoke, good carrier bearing, zero balance on the machine.. Still shimmy?  Get your magnetic angle finder out.  The output and input flange faces are probably a few degrees off.  Shim the rear or lower the trans and itll clear up.