Another chainsaw dyno...

[Red97]

Have you looked into Thomson Shaft? If I remember correctly it has pretty tight tolerances. We used it in the machine shop I used to work at. I believe a lot of what we got was 1045 case hardened but if I remember correctly you could get it in 4140. I am unsure of the pricing on it though.

I had thought about that, could always grind through the hard and put in the keys. May be an option. Have to see how true this other one is.

 

[JimBear]

I had thought about that, could always grind through the hard and put in the keys. May be an option. Have to see how true this other one is.

That’s what we would do, mill in key ways.

 

[Red97]

That’s what we would do, mill in key ways.

Cheaper too... Might have to get a stick just to try out. Could just put the keys where i need them. Would hold up to the bearings a lot better.

 

[Red97]

Quick service.

Much better bearing fit.

All within .0015"

Have to make the outer support yet.

 

[srcarr52]

View attachment 250448

Quick service.

Much better bearing fit.

All within .0015"

Have to make the outer support yet.

I don't think you need an outer support. Then you'd have 3 bearings on the same shaft and it would be over constrained.

 

[Dieselshawn]

(Raises hand) Mr. Red97, I have a quick question if you don’t mind.

Is it possible to move the chain pulley next to the bearing post?

That would most likely get rid of your vibration and shaft flexing unless that’s already been done?

Then it’s possible a 3rd bearing post is not likely needed?

 

[Red97]

I don't think you need an outer support. Then you'd have 3 bearings on the same shaft and it would be over constrained.

I keep going back and fourth... This shaft with the proper bearing fit sure showed the misalignment in the bearing blocks.

(Raises hand) Mr. Red97, I have a quick question if you don’t mind.

Is it possible to move the chain pulley next to the bearing post?

That would most likely get rid of your vibration and shaft flexing unless that’s already been done?

Then it’s possible a 3rd bearing post is not likely needed?

View attachment 250453

I am moving it over about 1". It will start to crowd the tq arm and controls on some of the larger powerheads. For running and starting the saws.

I couldn't believe how much the shaft flexed with some of the stronger saws...

It's not really a vibration I am trying to get rid of. It is excessive runout/wobble at the shaft. That keeps the whipping motion out of the arm. This should be 10x better than before.

 

[spencerpaving]

More bearings would make more friction losses....But it shouldn't matter because all saws would be on the same playing field

 

[Red97]

More bearings would make more friction losses....But it shouldn't matter because all saws would be on the same playing field

It could add just a touch, but not sure if it would even be measurable. Being all the runs are done from full speed down.

Not sure if that bit of deflection under load is really a problem or not?

 

[wcorey]

I am moving it over about 1". It will start to crowd the tq arm and controls on some of the larger powerheads. For running and starting the saws.

Can you move the bearing block over toward the sprocket instead?
And/or move the torque arm to vertical (up or down)...

 

[wcorey]

Not sure if that bit of deflection under load is really a problem or not?

It doesn't only deflect from the sprocket to the bearing, can translate wobble/resonance out through the whole length of the shaft...

 

[huskihl]

I’d be willing to wager that an extra bearing outside the sprocket would show less loss than flexing that shaft and losing it to harmonics.

 

[Nutball]

If you could keep the bearings lubed with something like WD40 there should be no noticeable losses from extra bearings. It's amazing how much longer bearings will spin for when WD40 is used.

 

[wcorey]

View attachment 250448

Quick service.

Holy chit, that was fast...!

 

[Dieselshawn]

A perfectly balanced setup frees the most hp.

An auto tech that I know of that had a car with a 425 hp 426 hemi in it.

He disassembled the engine, balanced all the pistons, cleaned the crank and polished the rods.

The end result without any other mods was 500 hp at the wheels and the engine ran a lot smoother.

 

[spencerpaving]

If you could keep the bearings lubed with something like WD40 there should be no noticeable losses from extra bearings. It's amazing how much longer bearings will spin for when WD40 is used.

We used to use that on the rear axle cassette on our racing carts....Lubed them after every heat with wd40....They spun free and would last the whole season

 

[Nutball]

How long was a season? I only trust WD40 as a use right after application kind of oil. It seems to dry up quick.

 

[Red97]

Can you move the bearing block over toward the sprocket instead?
And/or move the torque arm to vertical (up or down)...

It doesn't only deflect from the sprocket to the bearing, can translate wobble/resonance out through the whole length of the shaft...

Holy chit, that was fast...!

I could move the bearing over, but then I wouldn't have the room for a 3rd bearing.

Believe they want the tq arm as close to horizontal as can be. That way you can calibrate properly. I'd have to double check the manual, buy I'm pretty sure it is something along those lines.

That deflection is part of my concern. But also some saws are way easier to slip the chain over the power head. That 3rd bearing will make chain removal/sprocket change harder.

Was very surprised to see the shaft on the porch today.

A perfectly balanced setup frees the most hp.

An auto tech that I know of that had a car with a 425 hp 426 hemi in it.

He disassembled the engine, balanced all the pistons, cleaned the crank and polished the rods.

The end result without any other mods was 500 hp at the wheels and the engine ran a lot smoother.

This shaft showed a good bind when tightened down, had to do some shimming.

We used to use that on the rear axle cassette on our racing carts....Lubed them after every heat with wd40....They spun free and would last the whole season

I give the bearings a squirt occasionally. Seem nice and free still.

 

[spencerpaving]

How long was a season? I only trust WD40 as a use right after application kind of oil. It seems to dry up quick.

Season. Was a bout 4 months...it is a use right away application....Also sprayed wd40 on the tires to keep them soft

 

[wcorey]

I could move the bearing over, but then I wouldn't have the room for a 3rd bearing.

The sprocket being right next to the existing bearing should eliminate the need for a third bearing...