hollow chisel morticer problem

[mike s]

hi i have a multi-co pm12 and im experiencing a buzzing noise in the chisel
it seems that the drill is slightly out of line with the chisel causing it to rub against the inside and make a squeeking noise that makes the chisel extremely hot
i have tried with 3 bits and the problem is consistent
the drill bit and chisel are properly installed and the bit is the right depth in relation to the chisel
what am i doing wrong?
is there any way to fix this problem?
thanks

 

[Kane]

If you've tried several bits maybe the chisel is distorted ....

 

[Teckel]

Try a different chisel and see how you get on.

 

[mike s]

no what i meant was i tried various morticing chisels with bits

 

[Teckel]

Did this only just start lately.??

 

[mike s]

no it was like it when i bought it (second hand a few weeks ago) but it seems to have got worse :S

 

[mike s]

it is ok with a small chisel and drill but anything over 10mm rattle

 

[kirkpoore1]

no what i meant was i tried various morticing chisels with bits

So you've tried various chisel & bit sets? Then ruling out a bent chisel or bit, or we can assume one of two things--either the rotational axis of the motor isn't lined up with the center of the bit, or mounting point for the chisel is tilted a little and so the bit isn't parallel with the inside of the chisel. A similar problem would be if the chisel bushing is bored off center or at a tilt. (I don't know what your mortiser looks like, so I can't say if it uses a chisel bushing.) Does your machine use a drill chuck to hold the bit, or do you have bit bushings? If it uses a chuck, it might not be seated correctly. Any of these could be wrong, but I think the poorly seated chuck would be easiest to fix, followed by the off center/tilted bushing, then the tilted chisel mount. The out of alignment motor motor & chisel bore would be toughest.

Can you post some pictures?

See if you can determine where the rubbing is happening. You may be able to take a felt tip pen and coat the outer surface of the drill bit, then put the chisel & bit into the machine and turn it on briefly. The rubbing will wear off the ink. You may be able to turn the bit by hand to see or feel the rub point.

After that, we'll have more info to help with the diagnosis.

Kirk

 

[Teckel]

This will happen me when the bit is fitted up to close to the chisel. Also I'll get it with long periods of use. I just give it a shot of wd40. That shuts it up for a while.

Teckel

 

[kirkpoore1]

This will happen me when the bit is fitted up to close to the chisel. Also I'll get it with long periods of use. I just give it a shot of wd40. That shuts it up for a while.

Teckel

Teckel is right, if you have the bit mounted too high up in the chisel. And a little rubbing is to be expected even when properly set, since the bit will deflect a little as it cuts into the wood. But if your chisel or bit are getting hot enough to get discolored, you've got an issue.

Kirk

 

[9fingers]

What clearance between chisel and auger to you class as adequate? I use the thickness of a 2p coin - about 1.5mm I guess.

In order to get the chisel hot, I can only think that the clearance gap is closing under the pressure of cutting. Has the main thrust bearing worn?

Bob

 

[tomatwark]

Does it have a drill chuck or a grub screw to hold the auger in.

If it has a grub screw it may be the pressure of this is distorting the auger or not gripping it enough making the auger move up into the chisel in use, even after you have set it up correctly.

The 2 p trick is a good one but I have found that most new chisels have a groove machined into them where they but up to the bush which is the thickness of a 2p and I just use that as a guide.

The mulitco I use to have had a flat filed onto the augers that came with it for the grub screw to grip onto.

Tom

 

[dickm]

Probably a stupid comment, but are you sure the noise comes from the chisel? On my PM12, there is occasionally a buzz/rattle from the wings of the cover over the chuck which resonate with something; what you describe doesn't sound quite like a noise you'd get from the chisel.

But blueing of the bit/chisel does suggest something is very blunt.....

 

[mike s]

the noise is definitely from the chisel
its not the depth of the bit either, i have had the bit as low away from the chisel as i can and it still rattles.
i cant just make do with spraying wd40, it heats up so much that the wd40 would evaporate before long!
the rattling reduces a little when in a cut, it is very loud when not in a cut.
i will take some pictures tomorrow
the auger drill is held in a drill chuck and the chisel is held into the frame with a grub screw inside a bushing that is interchangeable for different sizes of bits (yes i am using the correct bushing for the chisels)
i will try removing and replacing the chuck and see if it fixes the problem, what is the best method to do so?
thanks

 

[9fingers]

Rattling is normal as far as I'm concerned between cuts but I can't see how you are generating significant heat by that process alone.

Rattling whilst cutting is normally when an auger has a point off centre either by being a cheap auger or poor sharpening.

Bob

 

[mike s]

it is more of a buzzing noise as the rattling is so fast and loud
trust me it gets hot, i dont know how but it does

 

[Benchwayze]

Mike,

If your bits are overheating, then you know you must be getting friction.


If setting the bit protrusion a bit more doesn't work, I would chuck a good drill-bit in the machine, and turn it by hand, with a dial-gauge against the shank of the drill. I can't give you any figures, but if there's obvious run-out, I would say that's the problem. Apart from 'budget' chisels, I don't know what could cause run-out, other than a bent shaft, or a faulty chuck.

When I bought my first Hollow-Chisel morticer, I had the overheating problem. I ruined a couple of bits, before I realised the setting was wrong. My Axminster model needs something a little thicker than a 2p coin, but I found an old washer that was ideal. I bought some good quality bits, and have not had a problem since.

Although, for larger, centred mortices, I do like to use a big router with a fence on each side of the timber. That way I get plenty of support, and I can centre the mortice just by turning the router through 180 degrees. I make another pass, and then cut the tenons to fit, using the bandsaw.

HTH

 

[Bradshaw Joinery]

When setting the bit, do you turn by hand before starting as i have used some chisel bit combos that when set in one poision and then turned the gap is tighter. After quarter turn.



Does it buzz from the off? Or after the first cut?

 

[tomatwark]

Phil

Is the heating up happening when you are making cuts or just by running the machine?

And what make of chisels are you using?

Tom

 

[Teckel]

Have you ran the machine without any bit in it?
I would suggest buy another chisel and bit of a size that is most common to your work and try that.
Put up a short video of the problem for us to see.