Two Questions: Mortise wallow and Tsaw overload

[Fred Bryant]

Question 1:
I have been trying to hand mortise ( 5/16 Narex Mortise chisel ). On shallow mortises it seems OK, but the top is wallowed out a little bit. On deeper mortises ( >2" ) the wallow is much worst. Now I understand that it is a developed skill, but I want to move from practice to projects. How much is OK?
On some 2 1/2" deep by 4" wide mortise, the top is wallowed out about 1/16" for a depth of ~3/8". Now the mortises very snug when I drive them home, so is that normal/OK?
I guess I can always peg them.
Question 2:
Talk to me about troubleshooting motor/motor overloads. I have been using a delta unisaw with a 3 HP motor. Hit the start button and the motor spins for a second and then the motor overload kicks out. Let the overload cool, and repeat. After two or three trys, the motor starts normally. It then will start and stop normaly for a while. After a long break ( lunch or overnite ) the overload kicks out again and I have to repeat the cycle. I have good voltage at the motor, but not sure how to measure inrush. The steady state running amps are good.
Thx's, Fred.

[Tony Wilkins]

I know there's smarter folks out there to trouble shoot but I'll get the ball rolling (at least on the first question). When you saw 'wallowed' are you talking about the 'sides' of the mortise or the 'ends' of the mortise. If the ends, is it due to bruising the end while prying out the waste? If so then be sure to leave a bit of room on either end until the final straight down chops to finish the mortise.

It it the sides I have a couple of ideas. First is positioning - be sure to put yourself at the end of the mortise where you can see if you are veering your chisel left or right to break down the sides of the mortise. Also, begin by paring down a pass or two with your mortise chisel to give a good place to register your chisel tip to begin chopping?

Smarter folks will be along soon I trust but there's my 2 cents.

[Fred Bryant]

side to side wallow. I keep back from the end and pare it straight as the last step.

[Tony Wilkins]

Then I definitely would try the paring to give a good registration. Do you think the error comes from holding out of square, from the striking, or from the pulling it out of the mortise? That said, if it's hidden by the shoulder it won't matter. I've even seen some that put a slight bevel on the end of the tenon and the top of the mortise to aid in assembly. The loss of end grain that effects won't effect the strength of the joint much and gives a place for glue squeeze out.

[Mike Henderson]

I drill out the mortise first, then pare to final size. I find it's easier and more accurate than chopping out with a pigsticker.

Mike

[harry strasil]

Some woodworking companies are offering and wood handle that you can insert and lock just the mortising chisel in and drill out or chop out the mortise undersize and then use the wood handled mortise chisel to finish it. Such as item 4208 from Peachtree Woodworking for example. zi can't remember where I got mine, but they were on an online short term sale .

As to your saw motor, you may have a bearing going out or if your motor is an open not enclosed motor it may have sawdust built up in it. You need to unplug it and roll the sawblade by hand, if it's hard to turn, you need to check the affor- mentioned things.

[Derek Cohen]

Question 1:
I have been trying to hand mortise ( 5/16 Narex Mortise chisel ). On shallow mortises it seems OK, but the top is wallowed out a little bit. On deeper mortises ( >2" ) the wallow is much worst. Now I understand that it is a developed skill, but I want to move from practice to projects. How much is OK?
On some 2 1/2" deep by 4" wide mortise, the top is wallowed out about 1/16" for a depth of ~3/8". Now the mortises very snug when I drive them home, so is that normal/OK?
I guess I can always peg them

Hi Fred

I suspect that you are driving your mortice chisel down in layers, and freeing it as you go deeper with a sideways wiggle. Perhaps you are not even aware of this as you work.

I go down as deeply as possible, which is aided by the technique of adding a clearance hole, and only clear with a backward pull.

See here: http://www.inthewoodshop.com/Furniture/MorticingByChisel.html

Regards from Perth

Derek

[Hilton Ralphs]

Fred, take a look at this video by Paul Sellers. He has a very no-frills approach to cutting mortises and the results speak for themselves.


http://www.youtube.com/watch?v=q_NXq7_TILA

[Jim Matthews]

It's important to note that Paul Seller's method is built on sharpening with a convex bevel.

There's a wedging action when driving a chisel that will force it to follow the angle of the front bevel.
If yours is not sharpened well, this can result in more tearing than chopping.

If you're having difficulty remaining on the straight (when chopping) use a spacer to register the exposed end of the chisel "above" the mortise.
That can be clamped in the vise with your workpiece, to maintain alignment.

This should be made from straight grained stock that's stiff and stable.
Laminate a piece of melamine countertop material for a bearing surface.

Every time you prepare to give the 'sticker a whack,
pull it snug against this spacer to keep things square.

FWIW - this is a task that my elbow finds intolerable, particularly on harder materials.
If the mortise is to be cut in oak, more than 1 inch deep, I use the method Mike mentioned.

******

I don't use a tablesaw, but would point to the starter capacitor on any motor that behaves this way.
A full cleaning (including a vacuum or compressed air clearance) of your motor windings should reveal anything that's loose.

If you can't find any binding, or misalignment that puts excess drag on the motor - have the starter cap checked.

Unplug any power tool before examining the workings.

[george wilson]

As said,your motor may be full of saw dust,but it could need a new starting switch(which is inside the motor),OR,the off-on switch may have a defective "heater" in it. A heater is a coil spring affair that gets hot when the motor is worked too hard,and flips the switch off.

Capacitor is another possibility. I'm not sure if your motor has a cap. or not. The old ones were repulsion induction,I think. But,I'm not an electrician.

You need to get this checked out. Your motor stopping in the middle of a cut can be quite dangerous. Don't get your fingers cut off to save calling an electrician.