Shopsmith Forums

What stalls a motor? Insufficient torque(a by product of available horsepower).

Now when slowing it down, slower feed rate is necessary to derive the benefit.

Yes slower feed rate will help without slowing it down.

Slower feed rate will help with faster saw blade.

Slowing feed allows more gullets to carry away the swarf.

Inertia does not help over time when a steady speed is involved. Flywheels work best when power is pulsing.(hit miss gasoline motors etc.)


Regardless it requires a given amount of torque to cut however is is supplied. If you want inertia, attach a steel sanding disk to the rear shaft! I do not think it will help ripping thick stock with a combination blade after the initial cutting.

Just to be clear, when I say I need to use a slow feed rate to prevent stalling, I mean slow as in "nearly imperceptible". Maybe a ripping blade is the answer

JPG wrote: Tue Nov 02, 2021 12:06 pm What stalls a motor? Insufficient torque(a by product of available horsepower).

Now when slowing it down, slower feed rate is necessary to derive the benefit.

Yes slower feed rate will help without slowing it down.

Slower feed rate will help with faster saw blade.

Slowing feed allows more gullets to carry away the swarf.

Inertia does not help over time when a steady speed is involved. Flywheels work best when power is pulsing.(hit miss gasoline motors etc.)


Regardless it requires a given amount of torque to cut however is is supplied. If you want inertia, attach a steel sanding disk to the rear shaft! I do not think it will help ripping thick stock with a combination blade after the initial cutting.

Thanks JPG. I am okay with being wrong, but I just felt like I had to ask the question. I totally get how slower feed rate helps with binding, though it does increase the risk of burning. For me, my intuition tells me that I should speed up the saw blade, not slow it down to help with binding (after all other binding "fixes" have been applied). I know some things are counter-intuitive and this may be one of those. My logic mind easily sees how increased torque due to lower rotational speed could help with binding. Not trying to make too big a deal out of this, but I just thought it was worth challenging the assumption that lower sawblade speeds are preferred when binding happens. I certainly don't want to do any experiments in this as it could lead to unsafe conditions, e.g. kickback. Just curious if anyone has already attempted this, e.g. raising vs. lowering sawblade speed during binding?

HopefulSSer wrote: Tue Nov 02, 2021 9:33 am My Mk V is an earlier one with the 3/4 hp motor. I know later they uprated the motor to 1.125 hp which implies to me that mine will be somewhat underpowered. But how underpowered?

My Mk 5 500 has a 3/4hp motor also, and I cut 2x4s just fine. I do have to be conscious of speed, but I don't have to go that slow. I have also cut them on my 10ER with a 1/2hp motor and that machine bogs down easily, but I could still do it. Even then it never seemed like I had to go "imperceptibly" slow. I do use a rip blade though.

My Mk 5 bogged down a bit the other day when I was cutting 1" MDF, but I think that was partly due to trying to keep it straight against the fence. Being 24"x48" it was a bit bulky, but I was able to do it. I cut it down to 32" wide for my router table. I used a platform sitting on my woodworking bench for outfeed support.

HopefulSSer wrote: Tue Nov 02, 2021 12:25 pm Just to be clear, when I say I need to use a slow feed rate to prevent stalling, I mean slow as in "nearly imperceptible". Maybe a ripping blade is the answer

Based on my experience, it should work way better than that. Even with a combo blade as long as it is reasonably clean and sharp. You should not always be on the edge of stalling, and it sounds like you are. Is it a carbide blade? If not, I would switch to a carbide blade even if it meant starting with a cheap one.

It's not a perfect test, but if you run your headstock at full speed it places more load on the motor. Will yours run at full speed? Don't try this with anything on the spindles unless the attachment is rated for full RPM.

- David

It's not a carbide-tipped blade. And yes, "always on the edge of stalling" is a good way to describe it.

The motor will run at full speed. If I do something I know I'm not supposed to -- turn it on with the dial set to full speed -- it takes it a while to come up to speed but it eventually gets there. (Nothing on the spindles)

Just ran an experiment. I cleaned the blade thoroughly with lacquer thinner and then waxed it. I cut some 1 ft lengths of 2x4 to rip. At a speed setting of 'R' and feeding it as fast as possible without significantly dragging down the motor, it took about 20 seconds to rip it in half. At a speed setting of "slow" I gave up after about 25 seconds and had only cut about 3 inches into the piece.

Aha. I think it's the blade. With the SS unplugged I put kerf in the partially-ripped piece onto the blade. It's very tight. It's a thin-kerf blade with no set so maybe some drag in normal, but it's tighter than expect. (Not that I really know what to expect -- I've never tried putting a blade like this onto its kerf)

HopefulSSer wrote: Tue Nov 02, 2021 2:43 pm Just ran an experiment. I cleaned the blade thoroughly with lacquer thinner and then waxed it. I cut some 1 ft lengths of 2x4 to rip. At a speed setting of 'R' and feeding it as fast as possible without significantly dragging down the motor, it took about 20 seconds to rip it in half. At a speed setting of "slow" I gave up after about 25 seconds and had only cut about 3 inches into the piece.

This kind of confirms my suspicion (faster sawblade is better than slower for not binding), but not completely. Wow, 20 seconds to rip a 1 ft long 2x4 is painstakingly slow, so I can see your concern. Wondering if you went up to "U" from "R" if the binding is the same or improved. By "slow" do you mean you had the speed dial turned all the way down? I don't think that is quite what the other forum members had in mind. I don't know what speed letter they would recommend, but "slow" might be too far down the speed dial to attempt ripping anything. My guess is you need a new blade, but don't forget to check the belt tension and whether it has slipped while doing these rips.

"slow" is waaaaytooo far down!

Thin kerf and ripping do not cohabitate.