Uses for a 5HP motor?

[Matt Day]

I can get a 5hp single phase 3450 rpm motor for $75 that came off an old Rockwell wedge bed planer. What could I use it for?

I'd like to replace my 3hp 3ph motor in my 20" bandsaw but that I'm sure would take some mounting plate mods, and the existing motor spins at 1720rpm. So if need to buy new pulleys to keep the same blade speed.

Any suggestions on what tin use it for?

[Jesse Busenitz]

I just bought one to put on my 16" jointer but it already had a homemade motor mount that was really simple to modify. I'm thinking I paid over 300 for my Leeson so if you think you might possibly have a use for it, I'd say grab it.

[Mike Henderson]

A 5HP single phase motor in good working condition is a deal at $75 (assuming it will run at 240V). I'd buy it immediately and then figure out what to do with it.

Mike

[ian maybury]

If you run the bandsaw at the same RPM with the 5HP as with the 3HP motor you won't see any very obvious difference - not unless on the smaller motor the saw is bogging in heavy cuts or something and able to take advantage of the extra torque. To get real benefit in terms of cutting speed it would likely require raising the blade speed to that of saws running 5HP and similar blade types. Which would likely require a change of pulley ratio.

Even that might be a bit of waste - depending on the construction of the saw. In that the ability to run heavy blade tension is important if the aim is to resaw thicker material. This to resist the extra tension in the blade arising from the increased torque/need to pull harder to get the balde through the cut, and also to keep the band accurately straight and the wheel coplanar. A flexi chassis might struggle to properly use the extra power and torque...

One common usage for a 5HP/3,450 RPM single phase motor is on a properly sized dust system running 6in ducts and a cyclone - a system to the same broad layout as the Clear Vue can be built DIY to the drawings on Bill Pentz's dust collection website for example….

[Allan Speers]

3450 rpm?

I think that limits your applications somewhat, as big pulleys don't always fit, plus good ones can be quite expensive.

It would make a very nice dust collector, attached to a 15" + blower.

[Matt Day]

Thanks for the input all. I think I might get it.

Ian: the big brother of my saw, the 24" version, comes with a 5 HP motor. I'm pretty sure mine is beefy enough for the 5HP. Link:
http://www.powermatic.com/us/en/p/20...0-460v/1791258
If anything, installing the 5HP would free up the VFD I currently use on it if i can get the blade speed right. What should I be aiming for? I could use the VFD on future machines I may need it for. Id need a new 5hp mag switch too, so I'll see if the seller has the switch or it will cost me another $80 for it from Griz.

A DIY cyclone project sounds like a great idea/alternative too. Might be better to design around the motor rather than trying to
Make it work on an existing machine.

[Bruce Wrenn]

Owning a Rockwell 13" planer, I can tell you this motor is about the size of a five gallon bucket.

[Mike Heidrick]

Keep the 3hp 3ph and add a VFD - you would then have awesome variable speed on an amazing saw. If you have bog down issues you need try a different blade. You would be foolish to swap it to a 1ph 5hp motor with the wrong rpm and mount.

[Mike Schuch]

Double check to make sure it has a standard shaft on it. A shaft for direct coupling to a pump will reduce it's usefulness in re-purposing.

[Mike Cutler]

Matt

You have no use for that motor, and you should tell me where it's at, so I can save you, and put it on the 16" Jointer I am restoring.,

All kidding aside, I would buy that motor and just store it until you find a use for it. The scrap copper value in it is half what it's being sold for. The value to someone restoring a piece of equipment could be even more, especially if it has the Rockwell logo on it.
Buy the motor.

[ian maybury]

Hi Matt. I'm not familiar with the Powermatic saws, and a quick look in the manual on your link didn't throw up a lot about the construction - but judging my some of the fittings like the fence suspect they are probably lighter than the heavy duty Italians like the Minimax/Centauro CO series, or the Agazzani N'RA.

It's hard to tell - most bandsaw makers seems to resist quoting weights despite it probably being a significant indicator of heft and hence (to a degree/presuming good design) of blade tensioning and vibration absorbtion capability. Powermatic only quote a shipping weight. (including the crate, tools - everything?) For what it's worth the heavy duty Italians tend to run hefty steel fabrications with heavy cast iron wheels and other parts. They then tend to offer one and possibly even two lighter and lower cost models in parallel - sometimes down to one with aluminium wheels and fences for example at the light end. There's no need for a hefty saw for e.g. tensioning narrow blades to cut profiles in thinner materials, and wheels with more camber may tolerate less precise set ups and be able to track very narrow blades.

TBH I was intending to suggest that there might not be a lot of benefit to fitting the bigger motor to your saw, and potentially some problems. It'd certainly need careful working through. The 5hp model PM seems despite the visual similarities to have a bigger chassis and could be a significantly stiffer saw. Why do it unless you have a definite problem or need? One definitely to watch out for is the reduction ratio on the belt drive - if the motor pulley is small there may be a risk of slip and/or premature wear. It'd need sitting down with a belt selection catalogue and running the numbers to sort out a good choice of pulleys. Space/fit of the motor might be an issue too. Then wiring/amp rating of cables, switches etc.

More blade speed in principle ups the cutting speed, and since wood isn't hard to cut very high speeds are tolerated by even ordinary carbon steel blades. As they run faster the bands get longer - so there's better cooling too. I'm no expert, but short of having noticed a very significant increase in cutting speed and hugely improved smoothness and tracking stability going from a medium duty 400mm to a heavy duty 600mm (24in) saw (an Agazzani NRA) am not aware of any great requirement to hit a particular number.

Saws vary widely, but the bigger and heavier models tend to run much faster. Lower blade speed if nothing else is a major cost saving on cheaper saws - it requires less HP to run a given blade and depth of cut. Less HP = less tension in the blade/permits a lighter construction. Plus balancing etc are much less critical.

An entry level 'toy'/modelling saw could run as low as 2,500ft/min, a reasonable quality but still hobby 16in model 3,500 ft/min or a bit more. Heavy duty Italians might run 4,200ft/min on a 20in saw, 5,100ft/min on a 24in and almost 6,000ft/min on a 32in. The big saws potentially have to handle much thicker work/longer cuts and hence need the extra speed, but it could be too that the much longer band (cooling) permits these higher speeds on basic blades - that they might not be advisable on a smaller saw with a shorter band...