I Wanna Build Something

[Ken Fitzgerald]

Paint it white...or somebody we know will whine a lot!

[Andy Hoyt]

Waa waa waa

[Bill Wyko]

Well, being a deisel I'm sure it has torque up the wazoo. My diesel ram has over 1000lbs of torque with minor mods. Diesels are made to load up so you should be able to turn a tree trunk if you get the right speed.

[Glenn Clabo]

Don't tempt him with the tree trunk idea...it is John "impossible just takes a little larger" Hart ya know. I'm sure he's already picked out his first tree in the back forty...eh John?

[Paul Engle]

John, on the gear reduction, a 13 speed truck trans works very well...The hydrualic shop test stand I work on in the ship yard at Long Beach Ca we used a 5 speed truck tranny coupled to a 200 hp electric motor from one of the ships Fire fighting supply pumps , and one of the test stands had a brownie attached 5/3 speed , thats some pretty low greaing and you could run that thru a 2 speed differential and go even lower and still not loose any torque . Granted you would have to get very close in the coupling and use air to change ranges but boy you could slow it down and the thing would handle oh say 80,000 lbs no sweat. with the right carrage you could put a whole tree on it and have lots to turn . Plenty of wrecking yards in the area , you could hook the diesel to the tranny by belt or chain or direct drive coupling even the tranny from a say C60 would give you 4 speeds or use one with pto and run it hydrualicly , 1st thru 4th Generation Vickers stuff is not that expensive , and a tilt / swash plate A unit would give you infinite speed control ,just don't spring a leak ...ugh been there done that .

[John Hart]

Yeah...why stop at just the trunk. Lets go for the whole tree! I'm sure the engine can handle what I intend to throw at it. Picture 4 amish guys running a powermatic planer, TS, and jointer simultaneously while running a 5 HP compressor...all off the same engine. It might be ugly but it sure knows how to go round and round.

Paul...I've given some thought to the transmission idea and I'm very open to the idea. You really think I can get a scrap tranny that'll work? I gotta hook up a kill mechanism though. I want this thing to stop when I get skeered.

Just down the road a piece, there's a bunch of trees that someone is clearing. Huge stumps. easy pickin's. There's also a sawmill nearby...little family operation. I walked around there on Sunday and they throw the burls away in a big pile.....Burls that are 2-3 feet in diameter. Gotta go talk to that guy.

[Christopher Zona]

Damp out the vibrations. It could get really ugly if your lathe hits your building's natural frequency.

[Christopher Zona]

I was thinking more about this today. It’s a bit long too.

Wow, where to begin? You mentioned 1800 rpm, is that at idle, or is the idle lower? Something to consider here is the engine’s own torsional vibrations, which typically are worse at idle. Just watch a tensioner on the accessory drive of a car. An engine doesn’t run at a constant rpm, but rather in a range, say ± 50 rpm due the cylinder firing.

The front end accessory drive is excited because of the inertia of the alternator rotor. Without getting too technical, the engine rpm and the alternator rpm can be and usually are out of phase with each other. What we design, where I work, to eliminate this is to allow the alternator to decouple from the system momentarily. This allows the alternator to speed up and slow down as required. Did I loose you?

Where am I going with this? The diesel’s own torsional vibrations can end up transmitting through whatever drive system you make. They may or may not magnify when you get to the spindle.

I think it may have been mentioned, but if you're using auto wrecker stuff, it would be a great way to solve a few problems.

Use the PTO from the diesel into a tranny, from the tranny to a belt drive to the head stock shaft. Use some sort of spring styled automatic tensioner like those found on a car. A tensioner usually will have some method of torsional damping in it. This will help to reduce the effects of the engine torsionals.

Plus, a tranny can do two other things (1) give a speed range while having the diesel at a constant rpm and (2) it will allow a means to ramp up the turning piece speed instead of giving the system a shock load. This will ease the torque applied to the spindle on start-up.

I imagine that a hydraulic master cylinder could be hooked up some how and then attach a disc and caliper to the spindle shaft.

Sorry that I was so long winded, but my mind was racing today about this.

[Bill Boehme]

Use the PTO from the diesel into a tranny, from the tranny to a belt drive to the head stock shaft. Use some sort of spring styled automatic tensioner ...... tranny can do two other things (1) give a speed range while having the diesel at a constant rpm and (2) it will allow a means to ramp up the turning piece speed instead of giving the system a shock load. This will ease the torque applied to the spindle on start-up.

I do hope that you guys realize that this may take woodturning into an entirely unanticipated direction -- I can see it now -- at some AAW Symposium in the future, immediately following the keynote address, the voice crackling on the public address system announces over a hushed crowd, "Gentlemen, start your lathes"! That can only lead to the obvious next step -- tailgate parties at the Symposium.

Bill

[Gary DeWitt]

What about air brakes from a semi? Seems they would be safest if you could figure out a way to shut off the power so as to not wreck some part of the "drive train" when emergency stopping. While we're being automotive, how about a pedal operated clutch? Linkage would be interesting, perhaps you could rig it with a rod near the floor, paralell to the ways, with a pedal that would slide along the rod making it possible to put the clutch in easy reach wherever you were turning at the time. On the other hand, perhaps you don't want to be anywhere near your spinning tree when you need to stop it turning!!
Glad to see this thread reactivated, this is fun!

[John Hart]

Here's a little information about the current setup with the engine. This 22 HP diesel has a clutch that is currently operated by a lever with linkage out to the shop. I bring the engine up to operating speed of 1800 RPM, then engage the clutch. Idle is somewhere around 700. The output shaft of the clutch drives a 6" 3-groove pulley, that drives the line shaft out to the shop. This line shaft used to drive all the woodworking equipment in the shop...but now only drives the air compressor and a 10 KW Generator on demand. Originally, I thought that I could engage a tensioner pulley to drive a Reeves-style pulley for ramp up and speed control. I also figgered that I could use a pneumatic 1/4 turn actuator to disengage the clutch in an emergency. This is the total depth of my thoughts on this subject so far.
The transmission idea is intriquing, but I have no money to sink into the project. (all funds must go to the renovation of the new house ) So, innovation must win the day here.

As far as speed stability, the generator has been my greatest source of data on this. When the generator is operating under a nominal load, everything is nice and steady. When demand from the house increases, like when the water heater kicks in and the microwave turns on and someone is blowdrying their hair, the generator puts a huge load on the engine (nearly 20 HP required sometimes). When this occurs, there is a total speed loss of 50 rpm at the generator driven pulley. I run some wave-form sensitive equipment as well, and it functions nicely with the generator, so that is a nice indicator of the frequency fluctuations. When I was monitoring heavily, I noted a 55 to 65 Hz fluctuation...all dependent on devices in the house randomly varying the load.

Vibration damping is of huge concern to me. Considering the mounting method of these structures and the high over-hung load of the wood on the spindle, I'm going to need some reinforcement. I fear that a rigid strut might come loose from it's mount due to vibration and stress, so I'm wondering about air-shocks for dampening at the top of the headstock.

[John Hart]

What about air brakes from a semi? Seems they would be safest if you could figure out a way to shut off the power so as to not wreck some part of the "drive train" when emergency stopping. While we're being automotive, how about a pedal operated clutch? Linkage would be interesting, perhaps you could rig it with a rod near the floor, paralell to the ways, with a pedal that would slide along the rod making it possible to put the clutch in easy reach wherever you were turning at the time. On the other hand, perhaps you don't want to be anywhere near your spinning tree when you need to stop it turning!!
Glad to see this thread reactivated, this is fun!

This is a good point Gary. If I had an emergency clutch disengagement with a pneumatic actuator, the same air system could operate a braking system simultaneously.

[John Hart]

I do hope that you guys realize that this may take woodturning into an entirely unanticipated direction -- I can see it now -- at some AAW Symposium in the future, immediately following the keynote address, the voice crackling on the public address system announces over a hushed crowd, "Gentlemen, start your lathes"! That can only lead to the obvious next step -- tailgate parties at the Symposium.

Bill

The tailgate parties have already begun. No facepaint as yet....but it's early.

[Glenn Clabo]

John,
Just to keep the juices flowing...
There are some surplus shock mounts out there...and may be around you at the local junk yards in the form of engine mounts. Here is one that gives you two options...http://www.surplussales.com/Cab-Rack...hockmount.html
The "Vibration Pads" may (I don't know the loads you are figuring on) work like they do here... http://www.vibrodynamics.com/english...ammers.htm#MRM
Or the "Giant Shock Mount" could work if you can figure it into the mounting scheme. They are rated for 550lbs each.

[John Hart]

Great links Glenn. Thank you. Now I have to do some calculations. Here's the dilemma: (And I'm going to talk in terms of centrifugal force, even though the experts say that centrifugal force is not a real force, it still can be calculated and it's easier to understand than centripetal force)

The equation m w**2r, describes the force that is exerted outward, from center, offered by a spinning object. m = mass, w = Angular Velocity in Radians per second, and r = radius of the object.

We also have to consider the aspect of the wood itself. If the world were perfect, then a piece of wood would have equally distributed densities and it would spin as a balanced mass, exerting force equally in all directions, thereby running smoothly. But, in our not so perfect world, a 100 pound piece of wood...perfectly round...will have unequal distribution of density and cause the lathe to wobble. If there was, say, a 5% disparity on one side, this would equate to a 5 pound weight, swinging on a string, (the diameter of our 100 pound piece of wood.)

Applying the formula at 200 RPM and 20" diameter wood, we get... 5 pounds * (20.94 Radians/sec)**2 * 10" = 21,924 lbs of radial force.

at 100 RPM the force is 5483 lbs
at 50 RPM, the force is 261 lbs
at 25 RPM, the force is 130 lbs

200 Rpm seems a tad out of the question, but only if the imbalance/weight exists. As the piece is turned, the disparity is decreased, and the weight is reduced, then it can be cranked up. The necessity to do this calculation...even roughly, is going to be a high priority methinks. Especially since, I'm going to have a 5 foot swing .

So.....what shock absorber will work? In Glenn's link, there's one rated at 500 pounds, and the headstock weighs more than that....but then, I would use more than one, and equally distribute them. Or, are you thinking, just for the support members?


No...I don't intend to put a 5 foot diameter piece of wood on it....But I think I need to design for the possibility.