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How to cut a scope base

DaveTooley

Gold $$ Contributor
Making a scope base today. I thought some of you could use this. Pretty simple and you're only limited by your imagination. I make Remington bases using the actual offset from front to rear. I use a stacked feeler gage to get the desired cant.
I'm making a base for a 1 1/2" diameter action with a 1" cutter.
1 divided by 1.5=.66
.66=41.3 degrees.
I know from my notes 41.5 works.


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Making a scope base today. I thought some of you could use this. Pretty simple and you're only limited by your imagination. I make Remington bases using the actual offset from front to rear. I use a stacked feeler gage to get the desired cant.
I'm making a base for a 1 1/2" diameter action with a 1" cutter.
1 divided by 1.5=.66
.66=41.3 degrees.
I know from my notes 41.5 works.


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View attachment 1520437
Dave,
How many MOA is the scope base cut for?
 
Like the feeler gauges for MOA.

I use the arc function on the DRO. Just a few passes with a 1.250 core box cutter makes a nice smooth arc.

I hate trammin' that head back in.
 
Marv Klotz has a free software calculator for these types of radius cuts. This type of operation actually cuts a slight ellipse but if you use the recommended cutter it minimizes it. RADIUS.ZIP is the file you want.

Like the feeler gauges for MOA.

I use the arc function on the DRO. Just a few passes with a 1.250 core box cutter makes a nice smooth arc.

I hate trammin' that head back in.
I use a mill very little. More of a drill press now for me. I have fluted probably 300+ barrels on it.
 
Yea smaller is better to a point on the cutter. I started with a 1" cutter and have never explored anything else for round actions. Use what you have thing. The rear bridge on a Remington, 1.940" radius, takes a larger cutter. I think I use 1 3/4".
I've never had a problem with all the bases I've made over the years. Very slightly undersize and you get a good fit. I've thought about a relief cut down the center but I've never seen the need. A couple of trial cuts on a piece of scrap to fine tune the angle is all that's needed.
 
Thank you Dave
Had I looked closer at your chart I would had seen the formula
Interesting way of doing the job.
In all my years as a job shop and maintance machinist I've never seen or heard a radius being cut that way.
 
Dave,
Very cool! Haven't seen this done for many moons. Very ingenious the things people come up with over the years. The head on my mill will not tilt! Damn it. I have also seen it done vertically with a fly cutter as I am sure you have too. Fun stuff!
Paul
 
Dave,
Very cool! Haven't seen this done for many moons. Very ingenious the things people come up with over the years. The head on my mill will not tilt! Damn it. I have also seen it done vertically with a fly cutter as I am sure you have too. Fun stuff!
Paul
I have a fly cutter I made in the late 80's. It cuts ever so slightly an undersize radius for Remington actions. I use it to radius the bedding pillars I use. I bed with the pillars attached so the majority of the contact patch is on the outside. Acts kinda like V-blocks.
 

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