Mortising machine--what am I doing wrong??!

[wood_newbie]

I have a newly purchased Delta 14-651 hollow-chisel mortiser, and I am using the included bit set.

No matter where I set the bit clearance, no matter how fast/slow I feed the bit, and no matter how deep I go per pass, my bit clogs with material almost instantly.

I'm using well-dried cherry, and the 5/16" bit seems to do okay. But as soon as I step up to the 3/8" bit, it clogs. Same with the 1/2".

I know the included bit sets aren't the highest quality, but I'd like to investigate technique mistakes before I go blaming my tools. (And sending more $$ to LV for their Japanese set!)

Any help would be mondo appreciated!!

BTW, thanks to charlieb web page about clearance setting!

[else24]

I've never used a mortise machine but I've always assumed they were a modified drill press, beefed up in spots.

Therefore, some adjustments might be in order. Like maybe, rpm? Is it adjustable, and have you tried slower or faster speeds to see if that made any difference?

[fredfighter]

Is the bit oriented so that the chip ejection slot empties into the part of the mortise that has already been made?

[wood_newbie]

I can't even get the first "hole" made...within the first 3/8" of plunge, the bit is already clogged. So far a second hole is out of the question!

[fredfighter]

Is the bit oriented so that the chip ejection slot empties into the part of the mortise that has already been made?

[Anonymous]

Is the bit FIRMLY locked up in the chuck ?? or is it slipping ??

[Leon]

Nope no adjustable speeds at least on the ones that I have seen.

[Leon]

Strange problem that I have never heard of. The bit should be turning FAST. Is it? YOU ARE CHANGING the bit when you change chisels aren't you. The bit is still spinning fast when actually drilling? And lastly, have you tried these chisel and bits on another type wood?

[wood_newbie]

Nope...chucked-up to within an inch of its life. When the bit clogs, it usually stalls the motor. (And if it doesn't stall it, I pretty much get that seemingly ever-familiar scent of burnt cherry...)

[Leon]

Is the waste stringy? How much does the bit stick out past the chisel? Is the bit a relative close fit inside the chisel? The chips should not be getting stuck between the insides of the chisel and the bit.

[Edwin Pawlowski]

You have to hone the chisel and sharpen the bits. On a stone, smooth the outside of the chisel. One the inside, Lee Valley has a tool for sharpening it. It is a cone shaped wheel. Take a small file to the bit and file the same angle as on the bottom of the cutting blade and on the side.

If you don't do these two steps, you will never get a good mortise. There may be better chisel and bit sets around but these as they come from the factory are crappy.

[charlie b]

I'm going to go with a dull bit. Not the spur that severs the grain at the outside of the hole, but the edge that peels off the wood for the hole. If dull it would tear out chunks instead. Chunks can clog things up whereas shavings won't.

If necessary file the edge then refine with slip stones. The sharper that edge the easier the drilling. The easier the drilling, the easier it is for the chisel to do its job.

As for the Forty Cent Method for setting the bit to chisel spacing - thank the Fisch rep. I just did the illustration and put it up on my site. That said - you're welcome. Pass it on when you can.

charlie b

[markm]

So you set the bit right? On mine it says to set the chisle 1/16" from seated then set the drill to seat, then move the chisle up to seated. Mine is a Powermatic and I have to feed it pretty fast and hard in short increments, going slow just starts to burn.

[wood_newbie]

I get very little waste before the jam, so it's hard to say, but best I can tell it's not stringy at all. And of course the material I clean out of the chisel is a wadded mess.

I've been using the technique on charlie b's site for setting the clearances, but I even tried huge swings either way on clearance and it didn't help.

As for how the bit fits inside the chisel, everything _seems_ okay, although I will say the machining on the bit itself is beyond horrid.

[wood_newbie]

Upon further inspection, if I had to guess, I'd say this is the problem. Nothing about these bits is sharp. Not one edge. Too, the machining marks left behind are a disgrace. The chisels themselves seem okay, but again, not great.

When I get home from work this evening, I'm going to chuck-up just the bit and leave the chisel off altogether and see how far I get.

Which is the hard part. Hell, the Fisch rep just told a story! Again, thanks for all the good info on your site...I mine that on a regular basis.

[Bigpole]

Are you sure you have the correct drill bit for the chisel?

[wood_newbie]

No question about it.

[Leon]

If you have rough spots along the bit the waste could be getting caught up on that. The bit should be smooth.

[Teamcasa]

As others have said, the bit itself is the culprit. They (mine) came from the factory virtually useless. After sharpening the bit, smoothing the waste flutes and honing the chisel, it works very well. I do use a bit of bees wax as a lubricant as well. This keeps the chips from getting stuck between the waste flutes and chisel.

Dave

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[charlie b]

Don't use just the bit. These puppies ARE NOT as beefy as their "dedicated just to making holes" cousins. To increase shavings/chip removal, the gullets (for want of a better term) are deeper than their cousings, and while they can take compression well, they can deflect more. Deflect enough and they snap - which is not good.

In fact, too much torque will also shear them into two parts - also not good.

charlie b