Technical ENLARGING A HOLE

who know how to enlarge a hole in 7 leaves of a spring,

I could only find a center bolt for a Model A Spring a little to big, or very small.

How do I enlarge the hole in each leaf?

 

I’d use a step drill bit. One leaf at a time ?

 

One leaf at a time with a carbide masonry bit at slow speed.

 

Quality drill bit. Cobalt?

I tried to drill a hole in a '37 Ford bumper ( can't recall why I wanted to do this) and the bits I had wouldn't even scratch the tough, springy material. Cobalt bit pissed through it!

Chris

 

Have you considered turning down the bolt instead? Tried Graingers or McMaster-Carr?

 

THIS^^^^^^^^ is the right answer

 

Rat Tail File

 

I have no idea what your buggy needs for a centering bolt so may I suggest an allen bolt?

 

Thats actually what I have used in the past now that you mention it.......

 

Are we talking about the head of the bolt, or the diameter of the hole.
If it’s the head of the bolt, I’ve made the head of a grade 8 bolt “round” on a bench grinder many times for the locator.

 

As above, you can grind or turn down the head of an Allen head bolt to suit the hole.

 

I got mine from Napa after finding the part number via their web site. Though this last time I did have trouble finding one for a rear and used an Allen as @Tman suggested

 

I've drilled more leaf springs than I can recall, and it's surprising how easy they drill, even without carbide bits!! That said, why does the hole need enlarging? If it's because the centering bolt doesn't fit, just buy a smaller size bolt. I buy Allen head cap screws in either 3/8" or 5/16" to use as centering pins.
If it's just a case of needing to relocate the axle, all you really need is to drill the main leaf for the new location, and then add the other leafs to it. I've done this on several occasions to move the rear axle, and only occasionally needed to trim one end of the next longest leaf off. They cut easily with my Milwaukie portaband saw also, so no need to buy new, or redrill more than one leaf.
My drill bits are Drill Hogg, and with cutting fluid they go through leaf springs like butter.

 

If you drill, turn the bit slow, with heavy pressure.



Bones

 

Drill bit RPM = (CS x 4)/Drill Dia.

CS is cutting speed of the material, be safe and use 80, mile 1018 steel is 100. So if the drill is .375" your RPM will be around 850.

 

I used a 5/16" grade 8 bolt on my stock 31 spring. No drilling required.

 

You gave me a flashback of a JC 101 machine shop class!

 

https://thirdgenauto.com/ford-bolts/
Spring Center Bolts
R-93-01 1932-1934 Front Spring Bolt and square Nut $ 5.95/pkg
R-93-02 1932-1934 Rear Spring Bolt and square Nut $ 5.95/pkg
R-93-03 1935-1948 Front Spring Bolt and square Nut (fine thread) $ 5.95/pkg
R-93-04 1935-1948 Rear Spring Bolt and square Nut (fine thread) $ 5.95/pkg

 

This beats trying to drill springs in my opinion.

 

he probably just needs to grind out the rust and dirt making his hole too small

 

been there, done that

 

Drill springs has always been an art to me . The masonry bit slowly has always done the task for me , I always had the weld shop resharpen the bit to a steel bit shape before trying , the task . They had a diamond sharpener to grind the Tungsten , for TIG torches .

 

I learned this 42 years ago.

 

With a regular drill, go even slower, treat it like a cutting speed of something harder, go down to 60 which puts the RPM at 600. If you have a decent countersink, do that first to make it easier on the drill.