Vertical Mill inletting tools

[Pablo]

Was curious if you guys would fill me in on the tooling used in a vertical mill to do inletting and opening up barrel channels? I recently bought a mill and don't have any tooling specifically for this.

 

[tobnpr]

Nothing more than typical straight and ball endmills for me.
HSS or carbide depends on stock material.
What else do you think you'd need?

 

[dskogman]

You can also use 1/2" drive core box router bits. They come in large radius sizes. I have no idea why the call them core box

 

[Wirelessguy2005]

+1
core box bits work awesome for opening up barrel channels

You can also use 1/2" drive core box router bits. They come in large radius sizes. I have no idea why the call them core box

 

[sean68]

+1 for router bits.

 

[hpshooter]

" I have no idea why the call them core box"

Goes back to them being used in foundry pattern shops to make core boxes to produce cylindrical cores. Mill two half round cavities, fit the halves with locating dowels, book them together, clamp them securely and fill with your choice of core sand, open the box, remove core (place it in a contoured "drier if oil bonded sand and bake to cure. Chemically bonded sands using urethane binder systems cure at room temperature. Some core sands are cured by gassing before removing from the core box.

A core is set in a mold cavity or assembled with other cores to produce areas of a casting that can't be drawn from the pattern. Think intake and exhaust ports on traditional IC engines or cooling water passages in engine blocks. They come in all sizes and shapes.

30 years of pouring liquid metal into holes in sand or 20 foot water cooled molds to make ductile iron water pipe to 90,000 lb ocean going diesel engine blocks and 1lb brake cylinders.

 

[Dusty Stevens]

" I have no idea why the call them core box"

Goes back to them being used in foundry pattern shops to make core boxes to produce cylindrical cores. Mill two half round cavities, fit the halves with locating dowels, book them together, clamp them securely and fill with your choice of core sand, open the box, remove core (place it in a contoured "drier if oil bonded sand and bake to cure. Chemically bonded sands using urethane binder systems cure at room temperature. Some core sands are cured by gassing before removing from the core box.

A core is set in a mold cavity or assembled with other cores to produce areas of a casting that can't be drawn from the pattern. Think intake and exhaust ports on traditional IC engines or cooling water passages in engine blocks. They come in all sizes and shapes.

30 years of pouring liquid metal into holes in sand or 20 foot water cooled molds to make ductile iron water pipe to 90,000 lb ocean going diesel engine blocks and 1lb brake cylinders.

My first machine shop job was at a pattern shop making sand molds. Never seen so many bridgeport mills and every attachment ever made in one spot.

 

[Roeder]

Was curious if you guys would fill me in on the tooling used in a vertical mill to do inletting and opening up barrel channels? I recently bought a mill and don't have any tooling specifically for this.

One thing to be aware of: The helix angle on conventional end mills tends to lift the material as it cuts and may contribute to chipping and splintering when machining gel coated fiberglass. The glass also dulls high speed steel tools quickly. Straight fluted carbide router bits are better and there are special tools designed for fiberglass that cut a very clean edge. There are also reverse helix (down cutting) tools that work well for this application as long as you aren't machining a closed pocket. There's a lot of stuff out there.

 

[Pablo]

Thanks for the suggestions guys, really appreciate it. It's been 35 years since I touched a mill, and back then we mostly made brackets to mount different hydraulic, and power steering pumps on various engines some offroad nuts were putting in mostly Jeeps. Have never touched a stock with one, was curious about what tool to use to cut a nice radius on the bottom of a barrel channel.

 

[SBS]

If you are going to be inletting fiberglass stocks, such as McMillan, look up "routing end mills for composites; fiberglass routers; diamond cut". These are solid carbide and the up/down small diamond cut produces very smooth results in such material. Be sure to run at fairly high speed and run a continuous vacuum to remove the dust and cool the tool. Shank sizes run from 1/8" to 3/4". The 1/4" shank/diameter cut works well for inletting the action area and for cutting the edges of the barrel channel where needed. Ordinary endmills do not cut the fiberglass cloth cleanly. I think the brand I use is ONSRUD; have also used ATRAX.

 

[Pablo]

If you are going to be inletting fiberglass stocks, such as McMillan, look up "routing end mills for composites; fiberglass routers; diamond cut". These are solid carbide and the up/down small diamond cut produces very smooth results in such material. Be sure to run at fairly high speed and run a continuous vacuum to remove the dust and cool the tool. Shank sizes run from 1/8" to 3/4". The 1/4" shank/diameter cut works well for inletting the action area and for cutting the edges of the barrel channel where needed. Ordinary endmills do not cut the fiberglass cloth cleanly. I think the brand I use is ONSRUD; have also used ATRAX.

SBS, do you know if these tools work well on wood also?

 

[SBS]

Pablo, don't know about using these for wood. I suspect that the small clearances between the diamond shaped cutting surfaces would get clogged with wood particles and perhaps with resin from the wood. Never tried wood with them as is not a recommended application. I have used sharp high speed end mills, either 2 or 4 flute with good results on wood; again as high a speed as possible without getting the wood too hot.

 

[tobnpr]

For wood laminates, carbide for me. The epoxy/glues are extremely hard and will dull HSS whether woodworking router bits or endmills, in short order.

 

[SBS]

For wood laminates, carbide for me. The epoxy/glues are extremely hard and will dull HSS whether woodworking router bits or endmills, in short order.

I agree, that's my experience on laminated wood also.

 

[Preacher]

I've used a lot of core box cutters on laminates over a lot of year's and never sharpened one yet..

 

[SBS]

I've used a lot of core box cutters on laminates over a lot of year's and never sharpened one yet..

Thanks for the recommendation, just never tried them, but I'll try them on a laminate next time I order some tooling.

 

[Ledd Slinger]

Is there a manufacturer that produces a 1.250" and 1.350" core box bits? Preferably carbide?

I found and ordered 1.125" and 0.5" core box bits on ebay. I figure I'll just make more passes for the time being. Be nice to open up straight 1.250" and 1.350" barrel channels with less passes and not having to adjust Y axis on the mill. Thanks

 

[dskogman]

Try amazon
https://www.amazon.com/dp/B01NAVAKKA/?tag=accuratescom-20

 

[Dusty Stevens]

Is there a manufacturer that produces a 1.250" and 1.350" core box bits? Preferably carbide?

I found and ordered 1.125" and 0.5" core box bits on ebay. I figure I'll just make more passes for the time being. Be nice to open up straight 1.250" and 1.350" barrel channels with less passes and not having to adjust Y axis on the mill. Thanks

Wouldnt you need a 1.5” one to open a barrel channel big enough?

 

[Ledd Slinger]

Wouldnt you need a 1.5” one to open a barrel channel big enough?

I suppose it would depend on the rifle and if the core box bit was ran to full depth. I know they come in different depths as well as different widths. My 700's and other factory actions are 1.200"-1.250" or less with 1.200" barrel shanks or less. Most customs are 1.350" and I run 1.250" barrel shanks. Probably wouldn't want a barrel channel opened up to a full 1.5" width if that's what you are implying.

Would want one with short depth and desired width so I would be able to tune the depth of the channel while maintaining vertical sidewalls on the inletting