DIY sawmill build

[Mesquite cutter]

I found some sheaves on surpluscenter for a pretty good price.  I am concerned about the maximum RPM for a 19" sheave.  They state 1325 rpm is the maximum for this size of a sheave.  Would that be too slow for a sawmill?  The predator more has a maximum rpm of 4000. 

Are the sheaves from Linn Lumber rated for a higher RPM?  Their website does not state that specs. 

[JRWoodchuck]

I have the same sheaves in my mill and have not had any issues running them faster than that. 

[Ianab]

Generally you gear down the drive from the motor with different sized pulleys to get the band speed you want. 1,000 rpm on 19" band wheel will give you about 5,000 feet/min on the band, which is the sort of number you want. So you pick your drive pulleys to gear down from ~3500 (where the motor is happy to run all day) to ~1,000 which is "in spec" for the sheaves. 

[RAYAR]

I found some sheaves on surpluscenter for a pretty good price.  I am concerned about the maximum RPM for a 19" sheave.  They state 1325 rpm is the maximum for this size of a sheave.  Would that be too slow for a sawmill?  The predator more has a maximum rpm of 4000.

My sheaves are the same size and I believe have the same RPM rating. My 13 HP engine has a 4-3/4" pulley and I believe that runs it under 1000 RPM for about 4500 FPM. Works just great.

[Mesquite cutter]

Okay so I would want the sheaves to be at about 1000 rpm and the motor at about 3000 rpm or max rpm?

[Mesquite cutter]

Also, I selected 1 7/16" bore for the sheaves but could not find a keyed shaft in that size.  The shafts go from 1 3/8" to 1.5".  

[Crusarius]

I have 19" wheels from Linn Lumber. I have a 4" pulley / clutch from engine to a 14" driven wheel. I have no idea what my rpm's are but it works perfectly. I also have the tapered bushings. I do not have a keyed shaft. I have had no issues at all with any of it.

oh yea, also running a 22 hp predator.

[JoshNZ]

Mine are all tapered bushings too. 22hp running 19" wheels through a double sheave jackshaft. The taper bushes gave me the willies too but they seem to work great.

[Crusarius]

once it was trued up and tightened I have no issues with them. I tried to remove the wheels one day so I could paint the shafts. It was not an easy task on the one, the other I didn't even try.

[Mesquite cutter]

Then if I use the tapered bushing from surplus center I will not need the keyed shaft?  The bushing comes with a slot to accommodate the key correct?

[Crusarius]

yes, it does. I am not sure why I did not put a key in mine. Maybe I did and forgot. but I have not noticed any issues without it. The engine bogs and I do not get any slippage of the band wheel

[JRWoodchuck]

Thanks to Ianab for the math refresher mine are right around the 5000' fpm. So 1000 rpm. Also don't remember using any key stock with my tapered bushings. 

[charles mann]

Not saying it wont hold, bc it seems its working for some folks. But the only thing a person is relying on to make things spin, it just the bushing. The key will help prevent it from spinning out 1 day. It wont hurt to put a key in it, and it keeps the environment out of the keyed slot. Better to have it and not need it, than need it and not have it. 

[Crusarius]

Think about a drill press. Majority of drill presses out there the only thing retaining the chuck is a taper and friction. There is no other threaded fastener. How often does your drill chuck fall out? Does it ever spin?

The tapered bushings have screws to tighten them up more than just friction.

[charles mann]

Think about a drill press. Majority of drill presses out there the only thing retaining the chuck is a taper and friction. There is no other threaded fastener. How often does your drill chuck fall out? Does it ever spin?

The tapered bushings have screws to tighten them up more than just friction.

Im not saying DONT put a key in it. Im saying its better have it, than not. 
Along the lines of a drill press, mine has MT4 and i have spun the housing around the tapered chuck. 
So in that instance, a keyed chuck would have been better. 

[JoshNZ]

Mine don't even have slots for keys. Are we talking about the same thing?

I'm using these below. Sleeve slides on shaft, pulley slides over bushing taper and ring bolts to pulley, on the other taper and snugs it all up. I've removed and replaced them a dozen times or so over building.



 

 

[Mesquite cutter]

But wouldn't I still need a keyed shaft for the pulley on the backside so the belt from the motor can spin the shaft?  Or do I use a tapered bushing on the back side also for the drive pulley?  

[Crusarius]

Do a search for split taper bushing on google and look at images. They have flanges and keys. They are only inserted from one side but hold the wheel incredibly well. alignment is as easy as tightening the bolts till the wheel runs true.

You can use the same type of bushing for the drive wheel. You can choose to use the key or not. I do not remember if I installed the key. Since I have a spare key in my leftover parts bin I do not think I did. 

The tighter you make the bolts on the split taper bushing the more the taper is jammed into the wheel. It will not move.

[Mesquite cutter]

Anybody know what size belt I would need for an 18.75 OD sheave from Surplus Center?

[RAYAR]

Anybody know what size belt I would need for an 18.75 OD sheave from Surplus Center?

I believe it's a 56" for a tight fit and a 57" for a looser fit, in a "B" belt.

[RAYAR]

The tapered bushing for this size pulley generally has six holes. Three are drilled holes that the bolts pass through and thread into the pulley, therefore, tightening (pulling) the bushing into the pulley.

The barrel of the split tapered bushing is split in two places and is keyed to the shaft. The barrel OD is also keyed to the drive component as well. The advantage of the split tapered bushing is it will hold, even if the fasteners become loose. Split tapered bushings are interchangeable between manufacturers.

To remove (release) the bushing and pulley from the shaft, remove the three screws and insert them into all threaded jack screw holes. Loosen the bushing by first tightening the screw furthest from the bushing saw slot, then, alternately tighten remaining screws. Keep tightening the screws in small but equal increments until the tapered sprocket/sheave and bushing disengage.

[Mesquite cutter]

Anybody know what size belt I would need for an 18.75 OD sheave from Surplus Center?

I believe it's a 56" for a tight fit and a 57" for a looser fit, in a "B" belt.

Will the loose fit still hold or should I use the tight fit to keep it from spinning on the pulley?

[Steve Crook]

I am using the 56,s and when it is time to replace I will switch to 57,s they go on and off easier and I still get sawdust behind them that is not easy to clean out. the 57,s will make it a little easier

[ktm250rider]

Anybody know what size belt I would need for an 18.75 OD sheave from Surplus Center?

I believe it's a 56" for a tight fit and a 57" for a looser fit, in a "B" belt.

HMMM I used a 59" type B56

[Mesquite cutter]

Anybody know what size belt I would need for an 18.75 OD sheave from Surplus Center?

I believe it's a 56" for a tight fit and a 57" for a looser fit, in a "B" belt.

HMMM I used a 59" type B56

How does the 59" work.  Is there slippage?