(10-30-2024, 09:51 AM)JDuke Wrote: If it was just a couple, I might do that, but I have 56 sewing machines and several of them would be better in portable boxes when looking for a new home.

I have also thought of making a router jig that clamps to the box and use that to enlarge the hole, but if I can find or make a forstner type bit I think I will be better off not going through several steps to make the same hole.

I suppose the other option since I have several, is to program my CNC to do it.

Duke

(10-31-2024, 10:55 AM)agerlach Wrote: My initial thought would be an adjustable auger (do vintage, the new ones stink), but that wouldn't leave a perfectly flat bottom.

I did come across this however, https://toolstoday.com/carbide-tipped-adjustable-counterbore-bits.html?srsltid=AfmBOoqdsv1mVyIwjeGrJvEK2joiCk5bc88CQxOugdBG2-_s_jv9-9Ke

(10-31-2024, 07:36 PM)mike4244 Wrote: Duke ,I did not realize how many holes you need to bore. Mc Master Carr has a .06 reamer that you use after boring an undersize hole.
The teamer is expensive , $70.00 without shipping. Might be worth it for you. Other wise have a machinist make a D bit for you.
Easy enough job for a home shop machinist. Do a search for D- bit and you will see how it looks. The D-bit is used like a reamer but has no flutes. 
Since .6 is close to 5/8" you may need to have the chuck end turned down to 1/2" or 3/8" . 
After boring  the hole with an undersize Forstner bit the D-bit bores the exact size. You may have to peck bore as the bit has no flutes. Experiment some , the closer the hole is to final size the easier it is to ream.
mike

(10-31-2024, 02:20 PM)kencombs Wrote: End mills are available in 29/64 which is about .001 oversize.   Should work well in a drill press, mill or CNC.

(11-01-2024, 08:52 AM)JDuke Wrote: By my calculation 19/32 is a little closer to the 3/5 or 0.6 inch that I am looking for.

With 19/32 being 0.59375 inches so about 7 thousandths under the 0.6 that I need.  I am willing to bet my drill press has enough run out to make that close enough to 0.6 for government work.

I am still going to grind a forstner bit down to see how it works, but I will keep the 19/32 end mill as a way to clean up the holes if the forstner bit isn’t satisfactory.

Thank you 

Duke

(10-31-2024, 07:36 PM)mike4244 Wrote: Duke ,I did not realize how many holes you need to bore. Mc Master Carr has a .06 reamer that you use after boring an undersize hole.
The teamer is expensive , $70.00 without shipping. Might be worth it for you. Other wise have a machinist make a D bit for you.
Easy enough job for a home shop machinist. Do a search for D- bit and you will see how it looks. The D-bit is used like a reamer but has no flutes. 

(11-01-2024, 08:06 AM)JDuke Wrote: I may look at this if grinding a forstner bit to size doesn’t give good results.

The D bit looks like a decent option if grinding a forstner bit down doesn’t work as well as I want.
I have a mill and lathe, and my son heat treats the knives that he makes, so we could probably make a D bit if we need to.

Hadn’t thought of an end mill, Ill have to dig through my drawer of end mills and see if I have one just to test that idea out.

(11-01-2024, 08:52 AM)JDuke Wrote: By my calculation 19/32 is a little closer to the 3/5 or 0.6 inch that I am looking for.
With 19/32 being 0.59375 inches so about 7 thousandths under the 0.6 that I need.  I am willing to bet my drill press has enough run out to make that close enough to 0.6 for government work.
I am still going to grind a forstner bit down to see how it works, but I will keep the 19/32 end mill as a way to clean up the holes if the forstner bit isn’t satisfactory.

(11-01-2024, 09:21 AM)kencombs Wrote: Your size may be correct.   I didn't calculate, just looked at the end mill size table at Mcmaster.com.  My go to place for odd stuff and info.