Help - table saw rise and fall isn't working

[ScottGoddard]

Hi All,

The rise and fall isn't working on my Deft table saw (it's a Harvey HW110SE) and i can't work out why. I have taken pieces apart for the rise and fall, and it now works a little (see video), but for the life of me, I can't understand why it's getting stuck.

 

[DBT85]

Did it work before you took it apart or did you take it apart just to ry and get it working? Since it appears to be rotating the gear ok I have to assume some part of the mechanism is binding on something somewhere else preventing it from going any further. If you try and assist the up/down movement does it go any better? With one of the gears removed are you able to manually make it rise and fall correctly?

 

[MARK.B.]

Might be just my eyes but that top rod looks to be moving up and down a little when you change direction

 

[ScottGoddard]

Did it work before you took it apart or did you take it apart just to ry and get it working? Since it appears to be rotating the gear ok I have to assume some part of the mechanism is binding on something somewhere else preventing it from going any further. If you try and assist the up/down movement does it go any better? With one of the gears removed are you able to manually make it rise and fall correctly?

It was working fine and then stopped, hence trying to 'fix' it

The unit (not sure of the correct term) that moves the blade up and down runs freely as had to move it when i took it apart.
The wheel and gear used to move the unit up and down spin freely
the rod that move the unit up and down - this i cant move by hand - it needs the key and gear in place, but turns fine for a couple of turns as you can see,

 

[ScottGoddard]

Might be just my eyes but that top rod looks to be moving up and down a little when you change direction

There is a small amount of play - but why would it stop after several full turns?

 

[baldkev]

I had a similar thing with my p/t rise and fall. Mine has a horizontal shaft from the rise/ fall and it joins a section just like yours. The vertical shaft goes up through the body with a nut and bolt on the top which was binding.
I found that by lifting the bolt it feed up the mechanism. I bought the machine second hand and its likely it previously had some kind of washer that dissapeared or broke down before i got it.

I now have a block of oak under this nut and washer and it works much better. I didnt get photos of the mechanism after the fix ( its about 300kg and i was in a hurry to not get crushed ) but i would guess the idea of the joint is the shafts probably need to cross each other centrally. Your top shaft is off to the right

 

[Illy]

If there is a a threaded rod (called a worm drive/gear ?) you might find the thread has worn so the raising element keeps slipping ? This happened to my fathers table saw. I think grease and sawdust can be quite abrasive over time.

 

[Stevekane]

I dont know anything about tablesaws but just from a general point of view it does apear that the top gear is running off centre, its too far forward as can be seen by the grease marks and its position,,so my guess would be that there is a thrust washer or bearing somewhere on that top shaft thats missing/ worn away. I think that those type of gears, worm drive, do need to be quite accuratly set in relation to each other to work well.
Steve.

 

[LJM]

I’d suggest we need to the the whole mechanism to diagnose; all we can see there is some gears working essentially ok, but what’s happening further down the line?

 

[Henniep]

It was working fine and then stopped, hence trying to 'fix' it

The unit (not sure of the correct term) that moves the blade up and down runs freely as had to move it when i took it apart.
The wheel and gear used to move the unit up and down spin freely
the rod that move the unit up and down - this i cant move by hand - it needs the key and gear in place, but turns fine for a couple of turns as you can see,

By the look of things the gear teeth are fairly fine and the play in the shaft is effecting the mesh. Methinks you've misplaced a very thin (shim) washer whilst stripping. True aligInment of the two gear is normally crucial.

 

[cowtown_eric]

I have only recently learned (today) that what I would call a shim washer, was also called an arbor washer

Eric

 

[Stevekane]

Just an afterthought, have you tried pulling on the rise and fall wheel whilst trying to turn it? if it is something like a thrust washer missing you would likely find that the shaft would be able to move back towards you.
Steve.

 

[ScottGoddard]

thanks all. Ill have to try and source a diagram of the correct setup and see if anything is missing or in the wrong place.

 

[baldkev]

Catch hold of the horizontal shaft and see if it moves in and out. If it does, just work out where to shim it so it centres over the cog below, then test it

 

[ScottGoddard]

Catch hold of the horizontal shaft and see if it moves in and out. If it does, just work out where to shim it so it centres over the cog below, then test it

Thanks, i didnt mess with the horizontal shaft at all, just the vertical one.

 

[ScottGoddard]

Catch hold of the horizontal shaft and see if it moves in and out. If it does, just work out where to shim it so it centres over the cog below, then test it

I couldn't get the shaft to move at all. Then last night it did and i have it all working now......however, still need to work out what is lose/missing or what happened to force it out of alignment. I am thinking that either a dust build-up or i knocked it a little to bind it. Then i probably forced it too much and that moved it completely out of alignment..


thanks all for your help

 

[baldkev]

I guess if it goes up and down freely, you'll have to wait until it fails again.... i was expecting you to say the horizontal shaft was loose