1-1/2 hp on a 1951 Delta Milwaukee?

[00lightning]

I currently have an old Delta 3/4 hp, 1725 rpm motor that appears to be original. Is the frame structure strong enough to run a 1-1/2 hp motor, 3450 rpm motor? I realise I will have reduce the motor pulley to maintain blade speed.
My main concern is rigidity of the frame. I have a newer 14" Delta X5 that has a 1-1/2 / 2.0 hp motor rated at 14 amps. The frame appears to be the same. Thoughts?
Thanks
Gilbert

[daddo]

I wouldn't worry about it. Belt tension will be the same, the only difference is starting torque.

As long as you can reduce the speed. Easiest is if the drive pulley can be reduced by 1/2.

[R Clark]

That's a good looking old saw!  

[fredhargis]

No problem at all with what you want to do, have at it...it will make the saw much more capable. I had the 28-245 (IIRC) and switched to a 1 HP motor from the 1/2 OEM, I wish I had went with 1.5 HP.

[Mike in kc]

I put a 3 horse and riser block on this HF saw several years ago and resawed LOTS of oak panels for projects, and its never cause a bit of problems.   I'm sure its not any more substantial as your delta, so I wouldn't worry about a 1-1/2 horse motor.

[TDKPE]

You won’t be able to reduce the drive sheave enough to run the saw at the design speed.  You’ll have to increase the driven sheave size also.  

Even if you could reduce it enough, there wouldn’t be enough contact area between the belt and sheave to be able to transmit the belt tension to drive the saw.  I think, from memory, that the drive sheave is 2-3/4” OD, which would make for a tiny sheave even if they made one that small, which I don’t think there is.

And remember that you’re doubling the rated continuous power, which means the short-time output power is considerably higher than that, too.  Better to use an 1800 rpm motor, or if you have to buy sheaves, change both, or even better, just double the size of the driven sheave (pretty big, though).  If you’re changing both, look into 3VX belts, which are actually thinner, but have a much higher power rating for a given drive sheave size than the common 4L or “A” belt.  I believe they can also bend tighter on smaller sheaves, especially the clogged style, which is what the “X” indicates.  Powermatic uses (or used, don’t know about now) 3VX belts on their contractor and cabinet saws.  The wedge angle is steeper, so they don’t work on sheaves designed for common 1/2” belts like 4L (fractional HP) or “A” (integral HP).

I think Semper Fi Mac looked into this a few years ago - he’s got the Shovel Head Harley thread going right now, which makes him easy to find.  



As to the frame, Delta had a 2 hp offering some years ago, and I can’t imagine anything was different with the frame as it was just a motor option.  If anything, the frame would have gotten lighter over the years, not heavier, so I wouldn’t worry about the structure being able to handle it.

[fredhargis]

Oops, missed the RPM part....TDPKE is on top of things (no surprise there).

[00lightning]

I calculated the blade speed on the original setup and it came to 2172 rpm. Isn't the desired speed arsound 3000sfpm? Or is it a function of available hp. Speed on X5 bandsaw is 3089 with 2 hp

[TDKPE]

I calculated the blade speed on the original setup and  it came to 2172 rpm.  Isn't the desired speed arsound 3000sfpm?  Or is it a function of available hp.  Speed on X5 bandsaw is 3089 with 2 hp

My 1961 catalog shows 3000 rpm blade speed, with a no. 5275 motor sheave which is 2-3/4” OD.  You may have different sheaves than what my catalog shows, but AFAIK, 3000 rpm is the number Delta has used for many decades.

14” and 3000 fpm is 818.5 rpm wheel speed, which is about a 2.11:1 reduction ratio for a 1725 rpm motor.  With a 2.75” OD motor sheave, which has a pitch diameter of around 2.6”, the arbor sheave would be about 5.5” PD, or 5.65” OD.  The catalog shows a 6” OD arbor sheave.  They may be calculating blade speed on the unloaded motor speed, which is a hair under 1800 rpm, which works out to about 820 rpm arbor speed using just the sheave OD numbers.

Close enough.

[00lightning]

On the Milwaukee I have 1724 motor, 2 75" on motor sheave and 8 " on top pulley. I calculate 2172 rpm. On X5 I have 3450 moter, 2.18" motor sheave and 9" top shreave. I calculate 3089 fpm