Criterion Boring Head Questions

[rwm]

Mine had a BB under the center screw from the factory but I can't argue with your logic.

 

[rronald]

I put a couple of BBs in yesterday. On both ends of the ways (the outer two screws in the set of three)..

It didn't seem to work. There were no recesses in the end of the set screws and the balls would not sit on the ends. I tried dropping them in place, but that resulted in a rough feel when moving the offset. So I gave up.

Without the BBs, the action is silky smooth. Absent some revelation about another way to install the BBs, I'm going to leave them out.

 

[RaisedByWolves]

The tolerances of the hole in the boring head and the diameter of the boring bar are pretty tight. Thus, if the setscrew holding the boring bar in creates a burr on the bar, which it will, that can make it tough to get out. Force helps.

This.

Someone either shoved a galled up bar in there or it has a burr from the set screw.

As what boring bar to use?

An endmill.

 

[RaisedByWolves]

I have reduced my shank/arbor length by about 50% and I pressed out the old boring bar. The problem with getting it out is that there was a cover (perhaps a dust cap) in the head bar holder on top of the hole for the bar. Seemed like the cover was pressed sheet metal. I mangled that cover, but I'm pretty sure it's not a problem to leave it out. And the boring bar slides in and out nicely now.

I'm trying to pick an indexable boring bar, perhaps based on the recommendations in this thread. But, I've been looking at pictures and I'm pretty sure that the original bar I got with the head is Right Handed. And, the 1/2" one linked to is Left Handed.

Do I have the "hand" correct? And, if I do...are you running your boring head using a left hand bar? Do you need to run the spindle with the opposite rotation from normal milling cutters and such?

The trouble you will encounter without that cap is if you insert a bar too far into the head it will contact the screw and bugger up the threads.

 

[rronald]

This.

Someone either shoved a galled up bar in there or it has a burr from the set screw.

As what boring bar to use?

An endmill.

I'll bite on this.

My question is.....how do I hold that end mill. I'm thinking of a 4mm endmill so I can make accurate holes down to 5mm or so. Or even 1/8th end mills for holes above ~ 3.5mm.

On the boring head, I could get a 1/2" shank ER20 holder that would slip into my boring head. That's getting a bit long, but it ought to work OK.

On the lathe, I'd want this mounted on the tool post. Not sure how to do this?

RR

 

[RaisedByWolves]

I'll bite on this.

My question is.....how do I hold that end mill. I'm thinking of a 4mm endmill so I can make accurate holes down to 5mm or so. Or even 1/8th end mills for holes above ~ 3.5mm.

On the boring head, I could get a 1/2" shank ER20 holder that would slip into my boring head. That's getting a bit long, but it ought to work OK.

On the lathe, I'd want this mounted on the tool post. Not sure how to do this?

RR

Modify an old 1/2" endmill would be the simplest option.

 

[rronald]

Modify an old 1/2" endmill would be the simplest option.

But that 1/2" end mill won't be very helpful in boring a 5mm hole. Unless I do a ton of grinding to reduce it to a 4 mm endmill with a 1/2" shank.

I guess a collet block could be mounted on the tool post.

 

[Firstram]

But that 1/2" end mill won't be very helpful in boring a 5mm hole. Unless I do a ton of grinding to reduce it to a 4 mm endmill with a 1/2" shank.

I guess a collet block could be mounted on the tool post.

Just make a 1/2” x 4 mm bushing with slit sides!

 

[Chipper5783]

Over a period of time and with numerous projects you will end up with all sorts of tooling for your boring head. It depends on the bore size, depth, obstructions, ID or OD and so on. Of course different tools will drive using different methods of holding (a sleeve, an intermediate bar etc). An end mill makes a good boring tool, especially for small holes - you don’t spin the EM, you use it like a single point tool, oriented so one tip engages the work piece (that EM trick works great on a lathe too - can easily bore holes down to 0.1”).

 

[RaisedByWolves]

But that 1/2" end mill won't be very helpful in boring a 5mm hole. Unless I do a ton of grinding to reduce it to a 4 mm endmill with a 1/2" shank.

I guess a collet block could be mounted on the tool post.

I have an entire drawer in my box at work full of tools that took me hours to make that have only seen minutes of use.

It’s all part of the game.