Shaper boring bar holder

[ErichKeane]

I've been meaning to do this project for a while (or something like it!) But until @lesrhorer asked me to cut a keyway for him, I didn't have the motivation.

Traditionally there are a few ways to make an internal shaping tool, but they tend to have the downside of only working with a single size bar, which limits the jobs you can do. Like a lathe boring bar, you want it as thick as possible to resist flexing.

I saw Fireball Tools do this project, which is to weld a 5c collet block to a bar and use that instead! I had also recently acquired a spare collet block set, so it was basically kismet. This makes it so I can use the cheap and highly available lathe boring bars of any size I want, up to the 1 1/8 5c collet I have.

First, I went to the local shop and picked up some 1"x2.5"x12" stock, which I then flattened and squared on the shaper. The small ends were done on the mill.

Then today, I spend a few minutes setting it up and welded it together. Looks like it will work a treat!

I DID screw up one thing, the set screw for the anti rotation pin I managed to get facing the wrong way, so it is now inaccessible. I considered cutting it apart and starting again, but the screw is retracted completely and hopefully won't cause problems in this configuration.

I also left the bar a little long, I might be cutting it down in the future if it is a problem.

 

[francist]

Have you had a chance to try it out yet? I’m interested to see how it cuts, I’ve only ever seen them with the cutting bit at 90 to the bar.

-frank

 

[ErichKeane]

I haven't, but that is a 45/90 degree bar, so I can flip it around to get a 90 degree bit. I just tossed it up to mock that up to make sure I had enough room behind the head for it to move and retract all the way.

 

[benmychree]

How do you plan to lock the clapper box for internal shaping?

 

[ErichKeane]

How do you plan to lock the clapper box for internal shaping?

I have a hydraulic tool lifter with a spring to keep it closed. You can see the flat head bolt at the top of the clapper.

 

[benmychree]

It will take more than a spring to hold it closed, it must be solidly locked down, it can be done by using a small machinist's jack between the upper part of the shank and the clapper box, but most shapers that I have seen have a setscrew through the lower bottom of the box into a recess in the clapper, done so that the setscrew tends to pull the clapper to seat solidly. My shaper is set up that way, it was done before I got it from government storage, I do not know if it was a factory job or was done later. Cutting keyways in a shaper is a PITA for many reasons, that is why I finally bought a Mitts & Merill keyseater for my shop downtown, it would cut up to a 1 1/4 keyseat 12" through.

 

[ErichKeane]

It will take more than a spring to hold it closed, it must be solidly locked down, it can be done by using a small machinist's jack between the upper part of the shank and the clapper box, but most shapers that I have seen have a setscrew through the lower bottom of the box into a recess in the clapper, done so that the setscrew tends to pull the clapper to seat solidly. My shaper is set up that way, it was done before I got it from government storage, I do not know if it was a factory job or was done later. Cutting keyways in a shaper is a PITA for many reasons, that is why I finally bought a Mitts & Merill keyseater for my shop downtown, it would cut up to a 1 1/4 keyseat 12" through.

That spring is pretty darn stout. It kept the clapper closed when trying to run the head backwards and accidentally had the tool extended. It outlasted my 5/8" cobolt cutting tool, which snapped.

The tool doesn't even really lift at all with any tension on the spring unless I have the lifter on.

That said, worst case I can put a piece of steel/aluminum/etc inside the spring to prevent it from moving.

 

[benmychree]

The problem is that with the overhung tool extending so far out from the hinge of the clapper is that the tool dragging in the cut on the return stroke tends to want to lift and try to jam up even more, begging to break something. I am a bit skeptical that the collet will be able to keep the bar tight without slipping axially. There is another type of bar that mounts directly in place of the tool post hele in place with a nut on the outside.

 

[ErichKeane]

The problem is that with the overhung tool extending so far out from the hinge of the clapper is that the tool dragging in the cut on the return stroke tends to want to lift and try to jam up even more, begging to break something. I am a bit skeptical that the collet will be able to keep the bar tight without slipping axially. There is another type of bar that mounts directly in place of the tool post hele in place with a nut on the outside.

Yep, I get the picture I think it ends up putting a few tons of force on the tool lifter, and I can overpower it with the spring, so I'm hoping thats enough. Otherwise I'll pop a piece of material down the center to lock it out.

I'm a little concerned about the collet/bar spinning as well, though the Fireball Tools guy made this and seemed happy with it. I figure worst case, I can pin the bar in place or something.

I made that other kind of bar for my 7" logan, which didn't have much room on the knee, so the 'drop' style seemed like it would take up too much space. That one did the internal shaping just fine, but I ended up wishing I'd made a few in a half dozen sizes. The hope here is I can swap out the bars for whatever size I need, its annoying to have made a 1/2" bar just to need to shape inside a 7/16" hole

 

[lesrhorer]

Wow! That is one boadacious shaper! Many thanks, again, for all your work on this.