# 45 or 60 degree dovetail cutter for making homemade boring head



## 9t8z28 (Jul 28, 2018)

I am about to begin making a boring head for my SX2 mill.  I will be using one of the numerous plans available to build the boring head but I have ran into an issue with the dovetail angle.  Everybodys plans require a 45 degree dovetail be cut into the body and slide.  I do not have a 45 degree dovetail cutter but I do have a 60 degree indexable dovetail cutter that I made using a single TCMT style insert similar to what Randy Richards makes.  Can I cut the dovetails 60 degrees and not have any issues?  I have read one persons opinion on dovetails that 45 degree is better for slideways that get clamped and they hold better to the radial and axial loads but I haven’t really seen any proof.  I would assume that 60 degrees will be fine as long as my design allows for a proper amount of material to support the dovetail.  
What are your alls opinions on this?  All of the plans I have seen call for a 45 degree dovetail.  Has anyone built a boring head using 60 degree dovetails or has anyone seen any plans for one that uses a 60 degree dovetail?

My other option is to build another indexable dovetail cutter that cuts 45 degree dovetails using a TCMT style insert.  I see that Dorian makes a 45 degree indexable dovetail cutter that uses triangular inserts like the TCMT.   Link here>>> https://www.ebay.com/p/Dovetail-Mil...8%26rvr_ts%3De2bf799e1640a9c55117a2eafff7d0bb   I assume I could angle the insert to give me the correct angle but the bottom of the insert would only make contact on the outer edge.  Before anyone says it, I am not wanting to purchase a 45 degree dovetail cutter.  I am unemployed at the moment and would prefer to not spend anymore money on this project.  

Lastly, if anyone has any boring heads plans they would recommend similar to the 2” Criterion round style head please post a link or info to help me find it.


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## benmychree (Jul 28, 2018)

What would be wrong with buying a HSS dovetail cutter?  HSS would cut much more freely and likely accurately, as well.


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## 9t8z28 (Jul 28, 2018)

As I stated I am unemployed and also I am asking if 45 degrees is better suited than 60 degrees in this application.  I dont see how a HSS cutter would be more accurate than an indexable cutter.   If I use the same cutter for both parts than the dovetails will match.  If I used 2 different cutters for each part than I could see an issue of the dovetails not matching.  


benmychree said:


> What would be wrong with buying a HSS dovetail cutter?  HSS would cut much more freely and likely accurately, as well.


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## jdedmon91 (Jul 29, 2018)

If I was in your situation I’d just use the 60 degree cutter and make everything around it. Personally I don’t think it make that much difference got your personal use


Sent from my iPhone using Tapatalk


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## 9t8z28 (Aug 11, 2018)

Thanks for your reply JD.  So far I have cut the main bodies internal 60 degree dovetails.  My order of opperations has not let me do the external dovetails of the slide yet.  Here is all I have done so far on the Steve Campbell design boring head.  Although it cannot be seen in the photos, the dovetail turned out perfect.  Very smooth finish.  I only took .005” per pass to a depth of .092”.  It took a while to cut at those shallow depths but I was concerned with breaking it.  The cutter was not dulled one bit.  I also had to make the 6-40 leadscrew since no local stores carried 6-40 SHCS and I was not about to purchase a minimum quantity of 25 for $18.  It took me 2 attempts to get the threads right.  This was my first time cutting 40 TPI on a part .138” thick!  Very challenging and a lot of patience....


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## 9t8z28 (Aug 18, 2018)

Here’s the boring head if anyone cares to see it.  I have about 4 more things to do and then its done.  After I make the nut I will be able to tell if the 60 degree dovetails will work or not.


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## TomS (Aug 18, 2018)

Very nice!


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## Z2V (Aug 18, 2018)

Looks really good, let us know how it works!


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## Firstram (Aug 18, 2018)

If looks make a difference in the quality of the cut, I'm sure it will work beautifully!


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## tweinke (Aug 18, 2018)

Gorgeous work! That is one fine looking boring head.


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