Thread: Tablesaw - Stuck Lock Knob Bolt

Try tightening it first, then try heat (as much as you can without melting the plastic knob. Maybe try to rotate the wheel assembly to try and unscrew it from below?

Does the shaft that the wheel is attached to still slide in the housing? Looking at the diagram the adjusting screw isn't attached to that shaft so it should just slide out if it's free. If you can get it out you would be able to see what the thread inside looks like to see if there is any damage from a previous owner. Maybe the end of the thread has been flared out and they have tried to screw the thread out and jamming it.

Originally Posted by Greg Q

Try tightening it first, then try heat (as much as you can without melting the plastic knob. Maybe try to rotate the wheel assembly to try and unscrew it from below?

The wheel assembly spins freely on the end, so not sure that can work. I tightened the nut and tried to over tighten to see if it would back out, but that doesn't work.
Will look to pick up a propane torch..

Originally Posted by Treecycle

Does the shaft that the wheel is attached to still slide in the housing? Looking at the diagram the adjusting screw isn't attached to that shaft so it should just slide out if it's free. If you can get it out you would be able to see what the thread inside looks like to see if there is any damage from a previous owner. Maybe the end of the thread has been flared out and they have tried to screw the thread out and jamming it.

I tried to yank it out, but no luck. That's why I thought it might be attached to the bolt. But it could just be 30years of tightness..Will keep trying to brute force it out with the side nut off.
Yes, I think it is bent so stuck in...cant get to it from the top because of the part around it.

Find a nut that should be the right thread and cut it into two halves with a thin cut-off disk.

Place each half in position on the thread and clamp using vice-grips then, using a spanner on the existing nut, tighten it down onto the clamped one as a 'locking nut.' There have been times I've tack welded the nut back together but, given a hefty pair of vice-grips, tacking is often not worth the effort.

That may give you the leverage needed to 'wiggle' the thread back'n'forth until you can get movement. Simultaneously tapping with a hammer can help.

This is a technique I've used with varying degrees of success (and failures! ) before I move on to riskier or more labour intensive alternatives.

WD40 is not really designed to loosen seized bolts. Try some Reducteur H72.

This might be a good one to post in the metal category . Pretty sure they would have a sure way to free it.

Originally Posted by woodhog

This might be a good one to post in the metal category . Pretty sure they would have a sure way to free it.

I tried to register on the metal forum but didn't get an activation email..

Originally Posted by Skew ChiDAMN!!

Find a nut that should be the right thread and cut it into two halves with a thin cut-off disk.

Thanks for the tip, will try this

I’d be trying to take the plastic knob off the top and then take the nut off the threaded rod almost all the way . Get it at the top slightly above the thread of the rod then tap with a hammer . Using the nut to protect the thread . If there is nothing in the welded nut down low against the shaft inside , like a broken bolt , then it should move .

It doesn’t make sense looking at that that it’s the turning of the plastic knob that raises and lowers the wheel . Otherwise shouldn’t there be a shoulder or a welded on washer on the threaded rod .
My guess is the threaded rod may be welded onto the internal shaft and the turning of the nut below the plastic knob raises the wheel . Gravity when it’s well oiled lowers it . And the knob is there for protection of the top or your hands ? Seems an odd set up and I’m probably wrong . Trying to get the knob and nut off would test that theory though .

Originally Posted by auscab

I’d be trying to take the plastic knob off the top and then take...

Half following what you're saying, but I think the nut is on just to lock it in place..

The fact that the shaft won't budge and the bolt won't budge, seperatly - makes me thing the bolt is threaded into the top of the shaft and is stuck. The winding bolt moves it up and down.
Having the side bolt too would seem overkill then.
But it also seems weird if the winding bolt is just sitting ontop of the shaft to set it's height...

I assume the saw below is the same or similar to yours. The adjusting screw will only be threaded through the bracket and not into the top of the sliding shaft that the wheel is attached to as turning the plastic knob would do nothing if it was. Just having the threaded stud pushing on the top of the shaft would cause it raise and lower the whole assembly as there is weight sitting on it at all times. You will need to get that shaft free and sliding. The screw that comes in from the side will be for locking the shaft when the correct height is reached and it probably locates on a flat machined up the side of the shaft to stop the shaft turning when you use the adjusting screw.

Woodman MBS300.JPG

Well, half a result today - The bolt is free, the shaft is not
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Managed to use a bigger pair of vice grips and wiggle the bolt back and forth and eventually got it to back out. The thread was just rusted and mangled..

The shaft though, is still stuck fast. I tried using a hammer and steel rod to bang it out, nothing moved and I can't build a lot of momentum as the frame is in the way of a good swing.
I then tried using a bit of steel rod and a car jack to try and force the shaft out and it wouldn't budge...the jack started bending

So somehow the shaft that should be free-sliding is wedged in. Must be some rust, but wow it must be some thing to be that rock solid..

You will be amazed how much grip a rusted shaft will have in a hole especially if it's a very neat fit. Best thing to do at the moment is squirt some penetrating fluid in the hole now you have the bolt out to fill the cavity and let it soak for a few days. Top it up if the level goes down during the soaking period. If the shaft has a flat machined down the whole side you could tightly wrap some insulation, duct or masking tape around the bottom so the penetrating liquid doesn't just flow straight out.
I don't suppose you have a small hydraulic bottle jack that would fit in the space and a very short piece of steel bar or high tensile bolt. If you have these you could try again after a few days of soaking. As said earlier by Bohdan, WD40 is not much good as a penetrant so get yourself something better. If worst comes to worst you may have to use a heating torch on the outer tube while applying pressure on the shaft to expand the tube creating a bit of clearance between the two.

Just a bit of an update - Success!
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There was a lot of rust as you can see. But there were also some small metal 'nibs' that were catching in the tube.

I used Seafoam Deep Creep and then once out was able to sand and dremel down to create smooth spots.

I have been able to put it all back together. Currently struggling with getting the sliding table parallel through the whole travel...but am working on it.

Thanks all for the help and suggestions.

Great job. By the look of that shaft its had moisture in there for some time to cause that much erosion. Trust you lubed it up well before reassembling to ensure it doesn't happen again. Sounds like you will be a convert of Seafoam now.