Project 2: Fly Cutter

[Rex Walters]

I've never used it, but maybe 410 stainless? Obviously not 300 series since it's magnetic.

 

[durableoreo]

View attachment 458911

This setup looks good to me. Probably best for Y-axis motion, like you've done.

The only other setup I can think of is a square collet block.

 

[pontiac428]

I decided to cold blue my fly cutter. I dropped it into a cup of oxpho-blue with giddy excitement and anxiously awaited the chemical reaction. I've had great success with this stuff in another project and really liked the way that turned out.

10, 20, 30 seconds go by and nothing was happening. This is used bluing that I had rebottled. I thought to myself maybe it has gone bad or inert or something. I test a piece of known cold rolled and it blackened almost instantly.

It appears I unknowingly made this fly cutter out of what I assume is stainless steel of some variety. I find this kind of funny because I was nervous about working with stainless steel. I understand it can be more difficult to machine. This is also means I have a 2" round over a foot long of stainless stock, which is good to know.

You clearly have some 400 series, just look at the color of the stock in the bandsaw. Then the stringy chip again says stainless. I was excited when you said you'd blue it, because I knew you would find out then- and you have. Cheers!

 

[JRT]

I really enjoyed this post. I want to make one of these now! What size set screws did you drill and tap for?

 

[jmiller]

I really enjoyed this post. I want to make one of these now! What size set screws did you drill and tap for?

1/4 -20 x 3/8. I bought one of those set screw assortments on Scamazon and that size just fit the piece well.

I would recommend making one. Not sure what your experience level is. I'm new to this hobby and found the project not too challenging.

 

[Rex Walters]

I'm no expert and suspect it doesn't make a huge difference, but somebody once told me to use fine threads for things like tool and work holding whenever possible (1/4-28 vs 1/4-20). More secure and finer adjustment.

 

[JRT]

Cool, thanks. I’m pretty new too but research things way too much when I get into them so I think I could make one. I just made a vise stop that I posted this morning, which is what led me here in the first place! Now I just need to determine what steel to use… Thanks.

 

[durableoreo]

I'm no expert and suspect it doesn't make a huge difference, but somebody once told me to use fine threads for things like tool and work holding whenever possible (1/4-28 vs 1/4-20). More secure and finer adjustment.

The minor diameter is larger on fine-thread screws, which is somewhat stronger than the coarse-thread.

 

[jmiller]

The minor diameter is larger on fine-thread screws, which is somewhat stronger than the coarse-thread.

All the threads are engaged on this setup for the length of the 3/8 set screw. They snug up real nice and give that satisfying SNAP when you pop them loose. But good information though, thank you. I'll keep that in mind for future projects.

 

[Rex Walters]

The minor diameter is larger on fine-thread screws

True. But I looked it up and there is only a 0.0175”difference in minor diameter between 1/4-20 UNC and 1/4-28 UNF.

If bolt strength was a concern for the application (not here, of course) it would make sense to bump up to 3/8” screws regardless of the pitch.

If I understand correctly, fine pitch threads are better for work/tool holding because of the shallower ramp of the thread (more secure and finer adjustment) not because the bolts are slightly stronger.

Somewhat counterintuitively, I was told coarse threads are better for thinner materials (sheet metal screws have coarse threads).