# Cutter Position Question



## Rick H (Jan 26, 2015)

I have a question for you Pro's and Pro-Am's that perhaps someone can give me an answer to.  I have been practicing cutting small dovetail slots in some aluminum blocks.  From what I have seen and read, the proper way to do this procedure is to use a straight cut end mill to take out as much material as possible and then switch to the dovetail cutter to put the dovetail slot in.  Where I am having some difficulty is in re-establishing the positioning of the dovetail cutter after swapping it out with the end mill cutter.  What seems to invariably happen is that my dovetail cutter is either too high or too low which in turn messes up the final cut.  Is there some solution I am unaware of in order to re-position the dovetail cutter after changing it out with the end mill keeping it at the same height the end mill was at?  I have tried several different ideas that I had, but the only one that came close was to put machinist dye on the slot in the work piece and come in very slowly with the dove tail cutter until I saw the dye just beginning to be removed and then make the final cut.

Thanks in advance for any help on this!!

Rick H.


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## Wreck™Wreck (Jan 26, 2015)

I believe that you have answered your own question if you are using a mill with the tools held in collets.


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## Rick H (Jan 26, 2015)

So using the dye and slowly coming in and/or down on the work piece is the correct procedure?  I had one idea that didn't work out due to the collet moving up as it was tightened.  

Rick H


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## caster (Jan 26, 2015)

You can also put paper or foil between the cutter and work and bring the cutter closer.  When the paper jams you are within the width of the paper.

Caster


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## Rick H (Jan 26, 2015)

I should have mentioned in my original post that I have a Grizzly G0729 and it uses R-8 collets for the end mills.  Thanks for the responses.  I thought there might be a more "scientific" way of doing this that was unknown to me.

Rick H.


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## Wreck™Wreck (Jan 26, 2015)

Rick H said:


> I should have mentioned in my original post that I have a Grizzly G0729 and it uses R-8 collets for the end mills.  Thanks for the responses.  I thought there might be a more "scientific" way of doing this that was unknown to me.
> 
> Rick H.


You can use a toolsetter but it will not be much faster then the way that you are doing it now, it will also cost more.


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## Vladymere (Jan 26, 2015)

Caster's method of using paper or foil is a good method.  Cigarette paper works very well for this due to it's thinness.

Vlad


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## JimDawson (Jan 26, 2015)

I use paper or dye depending on the situation.  Normally paper on the mill.  Most note book paper is 0.003, so it makes a good gauge.  Many times on the surface grinder I'll use dye.


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## Ulma Doctor (Jan 26, 2015)

for down and dirty, quick off- i use this method,

after switching tooling, just snug the endmill and return it to the work.
 put paper on the work, lower the cutter to the paper and tighten up the endmill, 
set and check the X and Z then,
back the tool form the work, fire up the mill and take the cut without looking back.


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## Rick H (Jan 27, 2015)

Thanks for the responses guys, I appreciate the help.

Rick H.


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## rgray (Jan 27, 2015)

Sometimes the step is intentional. Like the dovetail on a QCTP holder. Might be able to work that into your design at times.


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## Billh50 (Jan 27, 2015)

I use the paper method. It gets you within .003 of the surface. Sometimes, depending on what the dovetail is for, that is good enough.


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## chips&more (Jan 27, 2015)

Yes, the paper and dye work. I have also used chalk with good results…Good Luck, Dave.


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## digiex_chris (Jan 28, 2015)

Sometimes I use a feeler gauge. Leave the mill off, and lower the cutter till you feel a slight drag on the feeler gauge. Pull the feeler gauge out, and lower it the thickness of the gauge. 

I often setup my roughing cut with a normal endmill so that it's a few thousandths high, and use the dovetail cutter to clean up the bottom of the cut slightly the whole way across the dovetail as well.


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## uberlinuxgeek (Jan 28, 2015)

Hello,
I make many tool holders and qctp, what I do is touch off the top of the work with the end mill and hog out the material to the depth I want on the dro or you can use just the dials if that is all you have and leave 5 thou. The I pull that and put in the dovetail cutter again touching off the top of work again and bring down to final depth on dro or dial and make/enter the final cut. I at times leave more than 5 thou so I can have a finishing cut of 2 thou for a smooth surface. By always touching off with the cutter at the top you know where you are. Use a feeler gauge or paper or I at times will actually touch in a to future to be removed material.


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## kd4gij (Jan 28, 2015)

I Always gut 2 or 3 thou deaper with the endmill than I wan't to go with the dove tail cutter. It lessens the loade on the dove taile cutter. Most qctp holders are cut that way for that reason.


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## Rick H (Jan 29, 2015)

Well thanks for all the replies.  It helps me out a lot.  I never thought of the chalk idea.  I made a bunch of "practice cuts" in different material trying to come to a reasonably, repeatable way of doing these but my cuts were always slightly too big no matter what I did.  I kept thinking it was somehow related to the depth after switching to the dovetail cutter.  The cutter came from Grizzly and was marked as a 3/8" dovetail cutter.  I finally measured the cutter and it was actually .3865".  So the cutter I assume is too big to make a true 3/8" dovetail.  I ordered a better quality cutter today so I will see how things go after it arrives.

Rick H.


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## caster (Jan 29, 2015)

Rick,

I am currently making QCTP Holders and have a description in SHOP MADE TOOLING / QCTP -Tool Holders.  Take a look at the posting maybe it will help.


Caster


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## digiex_chris (Jan 29, 2015)

There's a method for measuring dovetails with dowel pins you could use to hit that dovetail dead on. Don't go full width, go about 3/4 then measure, then you know how much wider you need to go. You can then sneak up on it, to the point that you're a few thousandths under, then take tiny cuts till it fits well (or you hit your measurement if you trust it) Then the cutter diameter and spindle runout and other factors don't matter. Unfortunately I'm on a phone, so its hard to type math. Should be easy enough to search though.


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## digiex_chris (Jan 29, 2015)

Oops yeah, you'll need a cutter that's not the same size as the dovetail, you'll need one that's smaller so you can clean up both sides.


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## Rick H (Jan 30, 2015)

Ditto on the undersized dove tail cutter.  I guess I put too much trust in Grizzly sometimes and should have checked the actual cutter width before I started making cuts.  I just never guessed the cutter would be that much larger than 3/8 of an inch as stated in their catalog and on the cutter.

Rick H.


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## digiex_chris (Jan 30, 2015)

If you cut deeper, that cutter would work. Usually its the face above the dovetail that sets how deep the male end sits in it.


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