Subject: Re: Darex Drill Doctor experience

From: Glenn Day <[email-masked]>
Date: Fri, 20 Sep 1996 07:16:34 -0700

Mike
  I have had similar problems with the Drill Doctor also add that the
problems seem worse with small drills 3/32, 1/8 etc  then bigger drills
like 3/8. I also had problems getting the drill point centered. A
problem with small drill sizes is they are hard to align in the chuck. 
You can't reach the back of the drill to turn it to align it with the
setting pawls.  The instructions have a work-a-around for short drills
but it is a not real good.  Something to grip the end of the drill kind
of like a mechanical drafting pencil would be handy.  I have not talked
yet to Darex so there may be something I am doing wrong.

---

From: Mike Rehmus <[email-masked]>
Date: 20 Sep 1996 05:03:07 GMT

Well, after a three week wait, not two as promised, I got my new Drill Doctor.

I might be wrong (hope I am) but it doesn't seem to work all that well.

1.  The 22,000 rpm will burn the drill bit.

2.  The aligning device for positioning the drill in the collet is a bit tricky to 
operate.  It is somewhat easy to get the drill out of position.  Then you get no or a 
reverse clearance.

3.  The drills I sharpened all were ground with too little clearance.  Looks pretty 
good for brass, maybe too little for steel.  (however, one drill I tried cut 
reasonably well.  my eyes could be miscalibrated)  Whatever, this is where the setup 
seems the shakiest.

4.  The diamond wheel is quite rough and the ground finish on the drill bit is not 
what I'd call smooth.  (perhaps it will smooth out after some use.

5.  The grinding process leaves a fair burr behind the cutting edge which must be 
stoned off.  (this has never been a problem when free-hand grinding drill bits)

6.  The depth stop that sets clamping depth in the collet seems a bit too shallow on 
drills that have some damage.  Especially if the cutting edge has rounded off and a 
fair amount of material has to be removed.  You have to free-hand grind the tip into 
some semblance of proper geometry first.

Tomorrow, I'll call Darex and see what they have to say.  I'd like this thing to work 
so I don't have to save for a 'big professional model'.  More later.

Best regards,

Mike Rehmus

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From: anderson <[email-masked]>
Date: 21 Sep 1996 07:15:47 GMT

Mike Rehmus <[email-masked]> wrote:
Mike-
Mike called us at Darex, both Dave Bernard (the company president) 
and I have had good conversations with Mike who has been very helpful 
with his critique and with his questions.  In fact, we will re-do our
 operations manual because of his comments.  Most of this Mike 
already knows because of our phone conversations.  However it may 
help other Drill Doctor owners.

> 1.  The 22,000 rpm will burn the drill bit. #1 Yes, it can burn the 
point if you turn the chuck to slowly.  A brisk turning motion is
best.

> 2.  The aligning device for positioning the drill in the collet is a bit
tricky to operate.  It is somewhat easy to get the drill out of position.  
Then you get no or a reverse clearance. #2 At first the chuck and 
alignment may seem unfamiliar.  Easily overcome with some practice.
  
> 3.  The drills I sharpened all were ground with too little clearance.
Looks pretty good for brass, maybe too little for steel.  (however, 
one drill I tried cut reasonably well.  my eyes could be 
miscalibrated)  Whatever, this is where the setup seems the shakiest.
#3 The standard drill clearance (relief angle) produced is varies 
somewhat drill styles from around 10 to 12 degrees.  As Mike pointed 
out the drill cut “reasonably well."  The three settings allow for 
some clearance adjustment.   Mike agreed to let us examine some of 
the drills he sharpened.
 
> 4.  The diamond wheel is quite rough and the ground finish on the 
drill bit is not what I'd call smooth.  (perhaps it will smooth out 
after some use) #4 Again Mike is correct.  The 180 grit diamond wheel 
is an  electroplated wheel. Ideally, the diamond grit is slightly 
more than half-way submerged into the plating--thus held tight.  Of
course, a small percent of the diamonds are not submerged enough--
thus they protrude too much--causing roughness.  Initially, the wheel 
will feel rough  and grind rough until 20 or so "break-in" sharpenings.
The "sticking-out" diamonds are soon knocked off.  The remaining grit 
is all at same level (depth) thus producing a smooth finish.  
As Jim Donnelly of this newsgroup will attest the finish is very 
smooth, even on the split point facet.

> 5.  The grinding process leaves a fair burr behind the cutting edge 
which must be stoned off.  (this has never been a problem when 
free-hand grinding drill bits) #5 Mike is right but it doesn’t need 
to be stoned because the first turn it takes cutting material the 
burr falls off.  I flick the burr off with my fingers.   A thick burr 
indicates to me that Mike may be pushing too hard--therefore taking 
off too much material with each pass.  Anyway good point, Mike, we 
will explain this in the instructions.  

> 6.  The depth stop that sets clamping depth in the collet seems a 
bit too shallow on drills that have some damage.  Especially if the 
cutting edge has rounded off and a fair amount of material has to be 
removed.  You have to free-hand grind the tip into some semblance of 
proper geometry first. #6. The drill should clean up if set properly. 
My guess is the chuck was not tight enough and the drill was pushed 
back during sharpening.  Also as you may be able to visualize, if 
the old drill point angle is more acute than either the 118 or 135 
degree setting, your drills will be "champhered" until ground more.
 
Regards,
Curt Anderson
http://www.drilldr.com
http://www.darex.com

---

From: Mike Rehmus <[email-masked]>
Date: 21 Sep 1996 16:46:45 GMT

I called Darex Friday morning.  By 4 PM, they had called me twice. 

First the Marketing Manager called me to discuss the problems.  Was very concerned that the device work 
correctly.  He offered to swap the unit or refund my money if we could not make everything work correctly.

Second, an engineer called to discuss the issues.  I have been asked to sharpen a drill and mail it to them 
for evaluation.

These guys are interested in the product working correctly.  What a refreshing experience!

One interesting point (I think I've heard it before somewhere) is that a drill sharpened on any Darex machine 
will not look like those purchased off the shelf at the local hardware store.  They have a different approach 
to drill sharpening.  Apparently even their $600 or $3000 machines turn out drills with the same approximate 
characteristics.

>1.  The 22,000 rpm will burn the drill bit.

     Well, if you don't press too hard it seems OK.  Still it is a bit disturbing to hear the blender sound so 
close to one's prize drills.
>operate.  It is somewhat easy to get the drill out of position.  Then you get no or a 

This is still suspect.  It is also designed for drills of 'nominal' twist.  A high spiral drill is likely to 
be ground a bit 'off' using this alignment technique.  So would a non-twist drill.
>reasonably well.  my eyes could be miscalibrated)  Whatever, this is where the setup 

Tried a few more in a demo at the monthly club meeting last night.  Still, the clearance is
very small.  I sharpened a drill that had been abused by someone.  It took two passes because the corners were 
severly rounded.  The drill cut steel pretty good, however.

>what I'd call smooth.  (perhaps it will smooth out after some use.

It is starting to smooth out, just as Darex claimed.
>stoned off.  (this has never been a problem when free-hand grinding drill bits)

This is caused by the direction of the grind, the wheel sweeps toward the cutting edge from the back.  This 
doesn't seem to be much of a problem as the burr breaks right off when the first hole is drilled.
>some semblance of proper geometry first.
Always going to be the case.

>so I don't have to save for a 'big professional model'.  More later.

End of saga number two.  Overall, I'd guess the Drill Doctor will turn out to be a keeper.
Club members who own the more expensive grinders think this is a pretty good value and it
does more than their high-priced versions.

Best regards,

Mike Rehmus

---

From: Mike Rehmus <[email-masked]>
Date: 21 Sep 1996 16:46:43 GMT

Best regards,

Mike Rehmus

---

From: "Randolph Lee" <[email-masked]>
Date: 22 Sep 96 18:31:01 -0500

Well I am glad to see that others got theirs... still waiting for mine
ordered on the 27th or so... and due in a week they said... Yesterday I got
the bill via Smail with the actual flimsy for the CCarddated the 19th so
perhaps I will see it soon but I am bothered a bit by the rough wheel to
start with...

>smooth, even on the split point facet.

Mr Anderson in a letter to me answering my questions on the 26th said

>> about how many drills (say 1/4") will the wheel last for? 
> ------A mix of
>all drills from 3/32" to 3/4" on our larger capacity model has yielded
400+
>sharpenings on average in our in-house testings.  We did not test for only
>1/4" drills, but I'd expect similar numbers.  One sharpening service who
>tested one of the first DD's said he's gone past 500 sharpenings without
any
>sign of the wheel wearing down.  He did a mix of HSS and carbide drills. 
In
>other words, each sharpening removes 5 cents of the wheel's life.    
>>
>> and how much is a new wheel and how hard is it to change it?  
>------$20.
>Not hard at all.  The black cover pops off revealing the wheel.  The wheel
>is held on with two Phillip head screws.  We supply a wrench to hold the
hub
>as you turn the two screws.  

thus about 5% of the life of the wheel is given over to breaking it  in ...
Mike are these first 20 drills so rough that they need to be stoned or
quickly resharpened? is it in fact about 20 till it smooths out? or are we
tossing away a buck or two of the wheel life right off the bat?

perhaps it would be best to take 20 of your worst 'almost scrap' burned and
chipped drills and clean them up... then do them again and you would be up
and running... esp as that $20 new wheel will be about $25 or more with S&H
I bet...

90% of getting results out of the Martex drill sharpener was in aligning
the drill in the collet and not having the drill slip in the nylon collet
once it was set... that and well dressed wheel and it worked fairly well...
but the need to carefully check what the drill setting jig had done and
reset by hand when it was not right ment that I sold the unit on... That
and noise from the old electric drill I was running it on...... I hope for
better from the Drill Doctor.

well in any case I hope I get use mine before I go off line (and out of my
shop) for the month of Oct... otherwise I wont get much use out of that 30
day Money back clause they offer...

I will report on mine when I get it If time permits before I take off for
the UK on the 2ed...