Profiling

[90LX_Notch]

Much like my 0-80 single point experiment, this is one of my "experiments" that I didn't think would work, but it did. So, unfortunately, I didn't take pictures and only shot a video once I realized how well it was working.

I am building Gail Graham's "Lobo Pup Twin" as my current project. The crankcase calls out for a .469 radius at the bottom. I don't have a rotary table and was going nuts trying to figure out how I would machine it. For my own learning purposes, I do not look at other people's build logs; so I don't know how Gail did it.

I scribed the radius and roughed it out as well as could in the mill by repositioning it in the vise a bunch of times. I then made an arbor and mounted it in the lathe. My original idea was to use the lathe as a pseudo shaper and whittle away at the crankcase with a tool bit. That idea didn't work well. My next idea was to use my Dremel. This worked far better then I ever hoped.

I mounted the Dremel Flex Shaft in a block of aluminum and mounted it on the compound. A 1/8 endmill was set perpendicular and on center with the centerline of the crankcase. The part was indexed by hand very small increments after each pass. I should note that I held the chuck in position by hand while I cranked the carriage back and forth. Very light cuts are necessary due to the crappy bearings in the Flex Shaft but the end results are worth it. Because the endmill is cutting on the tangent point and small increments were used while indexing, a very good surface finished resulted with little tool marks. I sanded the part with 100 grit paper for less then a minute to obtain the finish in the video.

-Bob

[ame]http://www.youtube.com/watch?v=EXw-VoGucOg[/ame]

 

[Herbiev]

Great job Bob. Thanks for the video :bow:

 

[compspecial]

Great video, 90LX, and a great idea too. Its a wonder its not used more.
Stew.

 

[Mawitö]

Thanks for sharing Bob, is a great idea.

 

[Tin Falcon]

I mounted the Dremel Flex Shaft in a block of aluminum and mounted it on the compound. A 1/8 endmill was set perpendicular and on center with the centerline of the crankcase. The part was indexed by hand very small increments after each pass. I should note that I held the chuck in position by hand while I cranked the carriage back and forth. Very light cuts are necessary due to the crappy bearings in the Flex Shaft but the end results are worth it. Because the endmill is cutting on the tangent point and small increments were used while indexing, a very good surface finished resulted with little tool marks. I sanded the part with 100 grit paper for less then a minute to obtain the finish in the video

.


cool stuff. I have also used my dremmel flex shaft in the lathe and done milling. did you set up und stops for travel or go by eye
Tin

 

[woodnut]

Great idea, will have to remember this for later.

Thanks for the video.

John.

 

[90LX_Notch]

Thanks for the comments.

Tin- No stops were necessary on this particular part. The radius blended with rest of the crankcase by the time the ears came around.

 

[hobby]

Very good idea,
That was a good video for learning a new technique.

 

[rake60]

When I ran a CNC turning center we had programs written to do exactly that.
I never thought about doing it on a manual lathe.

Great idea Bob! Thm:

Rick