# Shop-made dovetail cutter from drill rod



## DaRiddler (Mar 5, 2014)

More as an exercise than anything else, I'm thinking of making a dovetail cutter to be used on a project in my mill.  Plan to make it out of water-hardening drill rod -- harden & temper it after making it.

I've forgotten where I got it, but the one photo shows the general idea.  Seems to me that one could either put the drill rod into a spin indexer and mill out four flats (see drawing #1) OR one could put the rod on end, drill four holes in the end, then turn it down, exposing four cutting edges.  One could even mill some relief on it (see drawing #3).

Has anyone here done this? or has anyone seen a write-up by someone who has done it?  by the way, yes, that is a napkin on which I made my cheesy sketches . . .


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## bvd1940 (Mar 5, 2014)

DaRiddler said:


> More as an exercise than anything else, I'm thinking of making a dovetail cutter to be used on a project in my mill.  Plan to make it out of water-hardening drill rod -- harden & temper it after making it.
> 
> I've forgotten where I got it, but the one photo shows the general idea.  Seems to me that one could either put the drill rod into a spin indexer and mill out four flats (see drawing #1) OR one could put the rod on end, drill four holes in the end, then turn it down, exposing four cutting edges.  One could even mill some relief on it (see drawing #3).
> 
> ...



do a search for diy dovetail cutter here and on Google and you will find lots of post,s on that subject and some will be with index-able inserts)


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## DMS (Mar 5, 2014)

Here is one I made a couple years ago. It looks familiar 

Material is W1 drill rod. There is no relief on the cutter. It did cut, but was pretty slow. I recommend adding some relief. You can do it with just a file if you are careful, and do it before filing.


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## xalky (Mar 6, 2014)

bvd1940 said:


> do a search for diy dovetail cutter here and on Google and you will find lots of post,s on that subject and some will be with index-able inserts)


 If you make it with inserts, Hardening it wont be an issue. You could probably make it out of mild steel.


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## Hawkeye (Mar 6, 2014)

As Marcel said, an indexable dovetail cutter will save you having to heat treat it. I made this one when I was doing my X2 CNC conversion. The shank is 7/8", for size reference. The pictures pretty much explain the process.






The rotary table is attached to the mill table rotated 30[SUP]o[/SUP] counter-clockwise to cut the recess for the insert. The endmill is set to the centre-line of the work, plus the thickness of the insert (below centre), so that the cutting face is on the centre.


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## JoeSixPack74 (Mar 7, 2014)

My to-do list keeps getting longer and longer...


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## Barnesrickw (Mar 7, 2014)

Let me know how that works.  Have some drill rod just begging to be made into one. 


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## Barnesrickw (Mar 7, 2014)

DaRiddler said:


> More as an exercise than anything else, I'm thinking of making a dovetail cutter to be used on a project in my mill.  Plan to make it out of water-hardening drill rod -- harden & temper it after making it.
> 
> I've forgotten where I got it, but the one photo shows the general idea.  Seems to me that one could either put the drill rod into a spin indexer and mill out four flats (see drawing #1) OR one could put the rod on end, drill four holes in the end, then turn it down, exposing four cutting edges.  One could even mill some relief on it (see drawing #3).
> 
> ...



I love napkin engineering.  Some amazing things have been designed on a napkin.  


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## John Hasler (Mar 7, 2014)

Barnesrickw said:


> I love napkin engineering.  Some amazing things have been designed on a napkin.
> 
> 
> Sent from my iPad using Tapatalk



I like that.  I could use that technique to make HSS cutters if I ever  get my ECM machine finished.  Use ECM to drill the holes, then use ECM  or grinding to reduce the diameter and grind with a die grinder in an eccentric fixture to get the relief.  Two or three flute would be easier.  Might be good enough for low-precision work in aluminum and non-metals.


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## docn8as (Mar 8, 2014)

Easiest &  cheapest  is to just  mill a centered flat  on the angled  end  of the   bar ..then  grind relief on the   two  two cutting  edges .like a  a flat  wood  bit ..if you  want  to  gild  the  lilly , file  some  slight  rake  on the  opposite  sides...harden in the drill press at 200 rpm ...quench while  running by  bringing  up the  brine  if  w-1 or  lite  oil  if  0-1 ( less  warpage  bt  vertical  quench  &  especiall 0-1 ..i makeing  rifle  cahmbering  reamers my  warpage  allowandce   for  grinding was  cut  in  1/2  this   way  .....draw at 375  in kitchen  oven ofr  0-1 ...put in  heated  oven  for  one  hour  ..shut it & let  coll .. Stone  edge  &  u r .done !
  Speed  is  1/2  of  high  speed fpm ..always  take  out  as  much  as  possible  w/ an  end mill before  using  a  dovetail  or  T slot  cutter  !
  best  wishes
doc
PS  for  multiflute  cutters  , a square  collet  block that  nolds  5 C  collets  is th e simplest  ..mayv abt $35 ??? fo hex & square ...OR you can MAKE a square bloclk w/ grub  screw  for the size  shank you have  ...great  accuracy  not  required ..in  fact  may be  better  if  a  tad  off ..irregular  flueted  cuitters  tend to  chatter  less.....i still have  two , nade  before the cheap china ones i  tempted  me to go against  my depresion  era  instincts ...


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## docn8as (Mar 8, 2014)

Fwiw ..while  at it  , you can  make  slotting  mills ,  ROUnd noes  mills  , taps , angle reamers, counter bores , what ever .....i still have a  set  of removable  pilot c/bores  i  made 40 yrs  gao ...# 4,6,8,10, 1/4 in .5/16 .3/8& 1/2 inch .
   ..but  cheap  china  stuff is  ruining  my  fun ...last  14 mm tap i made  cause i remembered them  costing so much  years  ago , took abt  2 hours  ....looked in catalog  ...on sale  for $12 ...back to  working  for  #5  /hour  again 
  best  wishes
doc
 oh  yeah  , in another  life  i made a  6x48 die  for some screws  for colt  45  grips ....screws  were a tad  tight  but  still went ok ....did not   knwow that  that a ten thou  oversize  tap  shud have been  used ..i just  used  teh  6x48 ace  tap that i  had 
 never  had  formal instruction , & therefore  made a  lot  of  scrap , but  the second  time  around  ,they  worked...i still keep a  worthless bannana shaped  reamer  from quenching  "flat "....never  again 

 i  mention this  only to tell you that while a  tool maker  apprenticeship wud  certainly  be  better  , you CAN  successfully come  in  the  back  door ...


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## Barnesrickw (Mar 8, 2014)

I think I like making the tools and jigs than the other projects.


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## DaRiddler (Mar 10, 2014)

Many thanks to each of you who responded to my original post -- I appreciate it!

Regarding dovetail cutters using inserts: I previously made a 60 degree dovetail cutter (see Bob Warfield's at cnccookbook.com or some posted above in this thread) but thought I'd make a 45 degree cutter for what is only occasional use.

I'll use the 45 degree cutter in another project (making a parting tool holder for QCTP) which I'll post here.  It uses a couple of 45 degree cuts; I haven't encountered a lot of those compared to 60 degree cuts, generally.

Thanks again for the feedback . . .


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## DaRiddler (Mar 11, 2014)

Doc, now you got me going . . . would the version of dovetail cutter you described involve milling a complete 180 degrees of the meat off of the business end of the cutter? ala a D-style reamer?  That's what I'm envisioning; correct me if I'm wrong. 

I have a square 5c collet block as well as a hex one. Here I was thinking of making it all complex using a spin indexer, while you have the faster way. Use a good vise stop and a collet block would make short work of it. 

I'm open to any more tips you have -- use this thread for whatever. For example, I didn't realize that quenching in a deliberate way (via drill press) yields less warpage!  Makes sense, I just hadn't heard about it. 

Is the general approach then to turn the drill rod to the right profile then mill flats, harden, temper, and stone?  Seems as if one could make anything from reamers to dovetail cutters to Woodruff cutters!  Not that the result would be art (in my case) but it might be fun and it might keep one going rather than stopped waiting for a purchased one to arrive. 

Doc, if you have pictures or any more tips on this, have at it. Same to everyone else who's been nice enough to read and/or respond in this thread.  I appreciate it.


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## JoeSixPack74 (Mar 11, 2014)

DaRiddler said:


> Many thanks to each of you who responded to my original post -- I appreciate it!
> 
> Regarding dovetail cutters using inserts: I previously made a 60 degree dovetail cutter (see Bob Warfield's at cnccookbook.com or some posted above in this thread) but thought I'd make a 45 degree cutter for what is only occasional use.
> 
> ...



I have been eying this 60° over on cnccookbook as of late.  How has it worked for you?  Did you use a TPGB or TNMP insert?


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## docn8as (Mar 12, 2014)

Dariddler 
             a D  bit  has  only  one  cutting  lip ........what i  described has  two ...the flat is  milled  from  both sidesafter  first turning  the point of teh bar to desired contour    the flat  is located  CENTRAL  on the  bar  end ..&  you essentially have  what wud  be a spear pointed  flat wood  bit  w/ out the spear  point but & shaped in a  flat  dovetail ........TWO  cutting  edges...
 re  quenching  vertical in  drill press...you have  not  heard of  this because it is  not in any  text i have  seen & most machinist  do not make  their  own reamers or  any  of  their  tooling  as  they  once  did ...& the  tool makers  do not  torch harden ...they  need to be  more  precise   industry  is  after  the  very  MAX number  of  parts  punched  out  before  retooling..be  prepared to  blow  out the  flame  if  you quench in oil (0-1)......
    i use the square collet  block for fluting taps w/ an endmill, as  well as special  multiflute cutters  when  needed......but the two lipped  cutter i  described is really easy  to  sharpen ..just  stone it 
 the  olde  tymers  wud take a  bar , heat  th e end & flatten it out which  expanded it  thne  shaped th e end like a flat  wood biit  w/ out the  spear point ///put a  center in teh  end ,mountd in teh  t/stock point ,th e flat  held w/ a  monkey  wrenc  & proceed to drill out  what  is  chucked  or  on a  face plate...there  were alos special holders  for th e flat  that  were mounted in  teh  tool post ....one  advantage  was  the  flat  bits  wud not grabinto the  material at  the  end  of  eh  cut  like a  twist  drill , but  any  real  depth  has to have  chips  blown  out ......
   FWIW  ...youcan  make  your own 2 lipped end mills  this  way ( slotting cutters )60deg ,,90degree pointed  cutters .....
 made a  corner  rounding mill this  way  once in aan emergency 
   best wishes 
doc
   i am getting  ready to take  some  3/8 flat stock 0-1 & make up a  short  flat  bit  head , insert it into a central slot of a  one in  bar &  rivet it  w/ 3  #16 nails ...make a 2 in & 1/2 in flat bit ....there  are  commercial  ones  but EXPENSIVE  that  use interchangeable  size SPADE bits ..
  best  wishes
doc


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## DaRiddler (Mar 13, 2014)

Doc, thanks for the clarification.  If you were to take some pictures of the project you mentioned, I think you'd find a lot of us would be interested.

JoeSixPack, I must admit I originally made the dovetail cutter with carbide insert thinking of the very common TNMG 322/321.  But that insert doesn't have any relief, and relief is necessary in this situation.  Here is a similar-sized insert on eBay that I'm going to pick up -- should fit the same way but with relief . . .

http://www.ebay.com/itm/TCGT-322-AN...164?pt=LH_DefaultDomain_0&hash=item29f0fb875c

From the several threads I've seen at Hobby Machinist and other blogs as well, the most common insert is TCMT -- being triangular, it provides three fresh points to use (not six, like TNMG, because TCMT isn't symmetrical front to back because of the relief).  I see TCMT 32.52 is used popularly.

Bob at cnccookbook.com has a nice writeup about making a dovetail cutter that uses an insert.  He says that he used TPGB because that's what he had on hand.  But he goes on to say that he wants to check out TCMT inserts as well.

Incidentally, the graphic that best explains insert sizes etc. to me is the following:


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## architard (Mar 13, 2014)

I too plan on making one of these. However when I started to look at what insert to build it for I looked at the commercial products. These all seem to use TDEX inserts. I don't see X on the chipbreaker section of DaRiddler's chart. After looking at some pictures of this type of insert I think X simply means it does not have a chipbreaker. They also don't seem to be used in anything but dovetail cutters. Has anyone else seen these types?

What would be the advantage of using a TDEX over a TCMT? 

I can see that the TDEX has greater relief, as well as since it doesn't have a chipbreaker you should be able to use both sides of it, if I'm correct in my understanding. 

I would assume using something less specialized than a TDEX means you can use it in another tool holder and you don't have to buy as many specialty inserts?

I'm still new to inserts and their are so many I tend to ask someone with more experience and just go with their preference.


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## ozzie34231 (Mar 12, 2017)

I recently posted a video on Youtube, 



 It is long, about 30 minutes and concerns making XL timing pulleys.
In the video I not only cut the pulleys, but *I show how to make the cutter from hardenable steel.* The cutter has 3 teeth and is properly relieved. I used my CNC lathe to cut the tooth form, but for a more common shape such as a dovetail or slotting tool, CNC would not be needed. Using CNC one could make any type of gear cutter needed.
Cheers,
Ozzie


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