3/5 of an inch forstner bit?

[Cabinet Monkey]

Vortex Tool will make a 3/5 bit for you if you have that many to do.

https://www.vortextool.com/?srsltid=AfmB...-G_JD1e7Gv

Anyone know why Singer used such a odd size hole instead of something standard ?


 
 

[Bob Vaughan]

I have a metal lathe, I’ll just have to come up with a makeshift tool post grinder.

A Dremel tool.

   

   

   

[Bob Vaughan]

Anyone know why Singer used such a odd size hole instead of something standard ?


 
 

That sewing machine head hinge design has been around since the late 1800s.  At that point in manufacturing history, there were very few "standard" sizes in manufacturing.  Besides, "sole source supplier" is an age-old concept.

[agerlach]

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-ad..._s_jv9-9Ke

[Roly]

Did you yourself measure the hinge part yourself as  I remember them being larger than 0.6" diameter .  The pin length was about that 0.6" you mention.   Are these what you are trying to recess ?   These are 1 1/8".  Roly

[JDuke]

Roly. I think your talking about the hinges for the cabinets.

Those are bigger and I believe they are a more standard size.
The ones you’re talking about secure from the top with a single wood screw into the cabinet.


The ones I’m talking about are the ones for the portable bentwood cases. And yes I have measured several of them to be sure they are a consistent size.
These have a machine thread that screws into the hinge from underneath.

[Cabinet Monkey]

That sewing machine head hinge design has been around since the late 1800s.  At that point in manufacturing history, there were very few "standard" sizes in manufacturing.  Besides, "sole source supplier" is an age-old concept.

Fractional inches were adopted by the U.S. government around 1830.

Sole /OEM suppliers will make whatever you want and are willing to pay for.

Your “no standards” explanation doesn’t sway me. 

[Roly]

Roly. I think your talking about the hinges for the cabinets.

Those are bigger and I believe they are a more standard size.
The ones you’re talking about secure from the top with a single wood screw into the cabinet.


The ones I’m talking about are the ones for the portable bentwood cases. And yes I have measured several of them to be sure they are a consistent size.
These have a machine thread that screws into the hinge from underneath.

You are correct as I missed the part about the bentwood case as I never seen one.  Roly

[BrentDH]

What about using your cnc to make a “guide” with the exact size hole you need and then using a router with a pattern bit following the guide?

[kencombs]

I found a forstner bit on amazon that was listed as 3/5” but it’s actually a 15mm bit.

3/5 or 0.6 inches is closer to 15.24mm

Why you may ask do I want  a 3/5 inch forstner bit.  
I am making a copy of the base of a bentwood case for a singer sewing machine, and the hinges that they used were 0.6 inch or 3/5
And need couple holes in the back of the case that are right around 0.6 inch.

15mm is to small and 16mm is too big.

I did try to grind a 16mm steel bit down to 15.24 and it was enough that it took most of the teeth off the forstner bit.

I also have ordered a 16mm carbide bit, and am going to try grinding the carbide down a little bit to get to the 15.24 or 15.25mm diameter.

Anyone have any other suggestions on how to get a good flat bottomed hole other than the above?

Thanks in advance.

Duke

End mills are available in 29/64 which is about .001 oversize.   Should work well in a drill press, mill or CNC.