# Large Radius on a Mill



## Stan (Dec 6, 2009)

Many weeks ago I asked for suggestions on hw to cut an 18" radius on my small mill. There were several suggestions and in particular Jason showed pictures for two methods. Some calculations showed that neither would work on my mill because the work required exceeded the size of my mill. I had to revert to my original idea of moving the workpiece with a leadscrew. Since I could use the leadscrew in the final project, a lot of work went into making the pieces. The screw is 316 SS single point threaded for a tight thread in the tapped hole in the steel follower which has to align with the reamed hole in the brass post.






The workpiece was clamped to a piece of 1/2" aluminum plate which was in turn mounted to the table on a pivot spaced above the table for the leadscrew to fit.





The slot was first cut with a ball end 1/4" carbide endmill and then opened up with a reground 3/8" HSS endmill and both edges cut to final size. The whole thing was a hairy-scary operation. No way to hold things solidly and to get the job done in a reasonable time I drove the leadscrew with a battery powered drill.





The rest of the project will go in another thread.


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## vlmarshall (Dec 6, 2009)

Impressive! :bow:


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## black85vette (Dec 6, 2009)

Gotta love innovation and solving problems in creative ways. Very nice.  Thm:


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## mu38&Bg# (Dec 6, 2009)

Is that a Benchman mill? I see them occasionally on Ebay. Is it fairly capable and accurate for it's size?


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## Stan (Dec 6, 2009)

The correct name is Benchmaster. They originally came as a vertical, a horizontal or both combined. Mine is just vertical with all the mounting holes to adapt the horizontal. They are a 6 x 36 knee mill with one serious drawback. They have no quill, so all vertical movement has to be done with the knee. I have owned it for about fifteen years and it has removed a lot of metal.

I made two mods to mine. I enlarged the spindle bore to MT3 from MT2 so I use MT3 collets and I drive it with a 1/2 HP industrial model DC motor with infinite speed control.


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## Hal (Dec 6, 2009)

Stan

Clever


Hal


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## mu38&Bg# (Dec 7, 2009)

Ah yes, Benchmaster. There is a company called Benchman that currently produces small CNC mills. I got the two confused.


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## 4156df (Dec 7, 2009)

Stan,

Very nicely done despite the hairy-scary aspect of it. Particularly liked the use of the drill for power feed.

By the way, the Benchmaster is the mill Rudy Kouhoupt used to build his models. It appears in all of his milling videos.

Dennis


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## Stan (Dec 7, 2009)

I was buying HSM magazine when Rudy was a regular contributor and noticed his Benchmaster (without a power feed) and his South Bend 9C which I was also using. Too bad that I never came close to duplicating Rudy's work when I had the same tools!


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## Quickj (Dec 8, 2009)

Here are some pictures of my Benchmaster.
It has the more normal 18" bed, all original paint etc.
I picked it up at an auction several years ago for $300.00, on this stand and with some tooling.
the only thing I have done to it is replace the Timkin roller bearings in the head and clean it up some.
I have a full set of 2 MT collets which I hardly ever use. 2 full sets of 2 MT endmill holders, a Kurt 4" vice,
An original 6" Benchmaster Rotary table, etc. It may not have a quill, but it has a knee.









http://s617.photobucket.com/albums/tt256/quickj_photos/Benchmaster/
More Pictures on my PhotoBucket page 

I don't think I would be able to do the same large radius on mine.


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