I have a Delta 14-070 drill press and a Delta 17-905 mortising
attachment. I am having lots of different problems in my first real
attempt at using the mortising attachment. At the moment I am using a
3/8" chisel. It is as sharp as I can make it.

1. I find it very difficult to clamp the collar of the chisel holder
around the split ring bushings in such a way as to keep it the split in
the bushings aligned with the split in the collar and to keep both
halves of the bushing aligned horizontally.

I have replaced the 5/16-18 nut and bolt supplied with a piece of
threaded rod and two pairs of jam nuts and it is better now, but still
slips from time to time.

2. I am running the drill press at its slowest speed (250 rpm) instead
of the recommended 650-2000 rpm because of the awful screeching noises I
get at the higher speed and the amount of heat generated at the chisel
tip. I actually have not tried any speed above 650 because my ears could
not stand it.

3. The interior of the chisel gets packed with the shavings from the
drill bit and not only don't the shavings fall out of the open side of
the chisel by themselves, they have to be pried out with an awl which
means that each 3/4" deep mortise takes 5 or 6 sequences of drill-stop
drill press-clear shavings-start drill press-drill. Really boring (pun
intended) and inconvenient.

I have waxed the inside of the chisel, basically by mortising a block of
wax. This helps, but not too much.

I have tried using this mortising attachment in pine, maple and matai.
All with approximately the same results. Are there tricks I should know?
I have RTFM-ed several times. Is this a bad mortising attachment? Should
I buy another model? Or should I go back to doing my mortises by hand or
router? (My current project involves several linear feet of mortise,
1/4" from the edge of the workpieces. This seems an ideal application
for a hollow chisel mortiser.)

Any advice appreciated.

Cheers,

Larry

You might want to sharpen the bit as well as the
chisel. You did sharpen the inside of the chisel
with one of those cone sharpeners right? And you
only polished the outside faces of the chisel, not
"sharpen" them?

If the bit isn't sharp it will tear out wood rather
than creating fine curlies. That may be why
all the clogging.

If you "sharpened" the outside of the chisel you
may have created a tapered chisel, narrower
on the cutting end and fatter above the area
that you "sharpened". That'll make pushing the
chisel down into the wood harder.

Then there's the gap between the bit and the
chisel. Too much and the bit may wander - and
rub the inside of the chisel. You can blow out the
bottom of a mortise that way. If the gap is
too small, the end of the bit rubs on the inside
of the end of the chisel, generating enough
heat to burn both the bit and the chisel. Try
The Forty Cent Method for setting the bit/chisel
gap.

http://home.comcast.net/~charliebcz/...tingTrick.html

If your stock isn't flat it can be hard to mortise,
the part moving as you apply pressure. Hollow
chisel mortisers don't do curved holes well at all.

If the stock isn't secured well and can move, even
a little, you've got the same problem. The hold
downs on the drill press mortising attachments
- how shall I say it - SUCK? Clamp the part if you
can - and as securely as you can.

charlie b

charlie b wrote:
You might want to sharpen the bit as well as the
chisel. You did sharpen the inside of the chisel
with one of those cone sharpeners right? And you
only polished the outside faces of the chisel, not
"sharpen" them?


Yes, I used a cone sharpener even though the Delta manual says not to.
On the outside all I did was break the burr off with a fine diamond stone.

I haven't sharpened the bit (yet).

Then there's the gap between the bit and the
chisel. Too much and the bit may wander - and
rub the inside of the chisel. You can blow out the
bottom of a mortise that way. If the gap is
too small, the end of the bit rubs on the inside
of the end of the chisel, generating enough
heat to burn both the bit and the chisel. Try
The Forty Cent Method for setting the bit/chisel
gap.

http://home.comcast.net/~charliebcz/...tingTrick.html

Thanks for this neat idea. Much better than the hit or miss method I was
using.

The hold
downs on the drill press mortising attachments
- how shall I say it - SUCK? Clamp the part if you
can - and as securely as you can.

I couldn't agree more. The work is well clamped with a toggle.

"Larry Spitz" wrote in message
...
I have a Delta 14-070 drill press and a Delta 17-905 mortising attachment.
I am having lots of different problems in my first real attempt at using
the mortising attachment. At the moment I am using a 3/8" chisel. It is as
sharp as I can make it.

And did you polish the 4 outer sides of the chisel also?



1. I find it very difficult to clamp the collar of the chisel holder
around the split ring bushings in such a way as to keep it the split in
the bushings aligned with the split in the collar and to keep both halves
of the bushing aligned horizontally.

Now you see why most that start out this way quickly graduate to the
dedicated mortiser if they continue.


2. I am running the drill press at its slowest speed (250 rpm) instead of
the recommended 650-2000 rpm because of the awful screeching noises I get
at the higher speed and the amount of heat generated at the chisel tip. I
actually have not tried any speed above 650 because my ears could not
stand it.

The screech is normal. Dedicated mortisers do this also. A little TopCote
on the bit inside the chisel will help for a little while. Use hearing
protection. You should have hearing protection in your shop, right?


3. The interior of the chisel gets packed with the shavings from the drill
bit and not only don't the shavings fall out of the open side of the
chisel by themselves, they have to be pried out with an awl which means
that each 3/4" deep mortise takes 5 or 6 sequences of drill-stop drill
press-clear shavings-start drill press-drill. Really boring (pun intended)
and inconvenient.

I would start with running at the proper speed and then maybe considering
getting a better quality set.

"Larry Spitz" wrote in message
...
charlie b wrote:
You might want to sharpen the bit as well as the
chisel. You did sharpen the inside of the chisel
with one of those cone sharpeners right? And you
only polished the outside faces of the chisel, not
"sharpen" them?


Yes, I used a cone sharpener even though the Delta manual says not to. On
the outside all I did was break the burr off with a fine diamond stone.


You need to polish the outer sides of the chisel to a mirror finish. This
will greatly decrease friction when plunging.

Leon wrote:

Now you see why most that start out this way quickly graduate to the
dedicated mortiser if they continue.

OK, a question.

Plan on building a small table using M/T. It is going to be a one shot
deal so investing in a dedicated mortiser doesn't make sense.

Based on this thread, a drill press attachment is a loser, so what is
the best approach?

A router /w/ a jig, then clean out corners /w/ a chisel maybe?

Lew

"Lew Hodgett" wrote in message
...
Leon wrote:

Now you see why most that start out this way quickly graduate to the
dedicated mortiser if they continue.

OK, a question.

Plan on building a small table using M/T. It is going to be a one shot
deal so investing in a dedicated mortiser doesn't make sense.

Based on this thread, a drill press attachment is a loser, so what is the
best approach?

A router /w/ a jig, then clean out corners /w/ a chisel maybe?

Lew

Router and jig will work but I used to use a forstener bit in a drill press
to hollow out the bulk and clean up with a chisel. Be sure to use a fence
so that you holes go in a straight line.

Leon wrote:

Router and jig will work but I used to use a forstener bit in a
drill press
to hollow out the bulk and clean up with a chisel. Be sure to use
a fence
so that you holes go in a straight line.


Can do that.

Matter of fact, as soon as I hit the send key, the thought occurred to me.

Thanks.

Lew

Lew Hodgett wrote:

Plan on building a small table using M/T. It is going to be a one shot
deal so investing in a dedicated mortiser doesn't make sense.

Based on this thread, a drill press attachment is a loser, so what is
the best approach?

A router /w/ a jig, then clean out corners /w/ a chisel maybe?

There's nothing that says mortices need to be square (unless they're
visible, then it's a personal preference thing). For me at least,
rounding over the tenons to match the mortices is quicker than squaring
up the mortice.

Chris

Lew Hodgett wrote:

Leon wrote:

Now you see why most that start out this way quickly graduate to the
dedicated mortiser if they continue.

OK, a question.

Plan on building a small table using M/T. It is going to be a one shot
deal so investing in a dedicated mortiser doesn't make sense.

Based on this thread, a drill press attachment is a loser, so what is
the best approach?

A router /w/ a jig, then clean out corners /w/ a chisel maybe?

Lew

Not sure why they waste time and your money with those
"free" drill press hollow chisel mortising "accessories".

Why not go with loose tenons. Mortises are fairly easy
to do with a plunge router and a spiral bit. Mortise both
parts, make up a couple of feet of tenon stock to match
the length and width, round over the edges with the router
and a quarter round bit and cut off what you need.

Trend makes a M&T jig that is so so for doing the tenons
but real easy for doing mortises.

http://home.comcast.net/~charliebcz/...endMTjig1.html

Or, if you've got a good fence for your plunge router and
like to make jigs, consider making this one, or a variation of
it

http://home.comcast.net/~charliebcz/...TenonJig1.html

charlie b

Not sure why they waste time and your money with those
"free" drill press hollow chisel mortising "accessories".

Why not go with loose tenons. Mortises are fairly easy
to do with a plunge router and a spiral bit. Mortise both
parts, make up a couple of feet of tenon stock to match
the length and width, round over the edges with the router
and a quarter round bit and cut off what you need.


Have a good set of carbide forstner bits and a decent fence for the
drill press.

As Leon suggested, seems pretty straight forward.

What do you think?

Lew