Need boring head recommendations

[ARC-170]

I wondered the same thing until I tried one. It cuts just fine, but the adjustment is not consistent at all. One turn of the adjuster knob would result in different distances each time, rather than being exactly the same. I'm not sure if there's too much slop in the adjuster screw or something else. I even accounted for backlash by screwing it one direction only and not backing it out.

I was thinking of getting a Precision Matthews or LMS boring head (they are about $100), as they have better quality control, but everyone has recommended Criterion.

That's probably the varying production tolerance you get with "no name" tooling. My ebay special cuts fine and the adjustments on the tool itself are also accurate. At least accurate enough for the work I do. I can easily work my impost boring head to .001. But as I said, it's probably more luck than anything else that my unbranded one works as good as it does.

I checked the new (used) Criterion head I received today and the cheap import with a dial indicator. The Criterion was spot on. The import is graduated in metric, .01mm per mark, BUT, when I checked it with the DI, it moved exactly .020" each revolution. It was at exactly .100" after 5 turns, when it should have been at .098". That would explain why the last hole I bored was off just a bit. It's 0.0004" per mark, which is really close to the 0.0003937" it theoretically should be.

 

[mikey]

I received the boring head today. I cleaned it all up and put a few drops of 3 in 1 oil on the screw and dovetail.

There are no ball bearings under the set screws. Looks like they take 1/8" diameter balls?

There were actually two set screws missing. The one that was there was not the knurled cup point. I bought 25 on Amazon. McMaster-Carr had 50 for about the same price, but I was able to use a gift card balance so it was actually cheaper for me on Amazon.

Criterion uses a light coat of grease on the dovetails and leadscrew.

There should be a ball bearing under each of the three gib screws - check again?

I think you'll be happy with the KBC bars. They look identical to Borite bars but cost significantly less.

 

[jbaccell]

I have a Criterion boring head and a no name import which were both purchased used off of eBay. I never knew until reading this thread that there were ball bearings under the gib screws. I just had to check both heads to be sure they were there and sure enough, both heads have ball bearings under the gib screws. Who knew....

 

[Eyerelief]

Been there done that more than once!

I have a Criterion boring head and a no name import which were both purchased used off of eBay. I never knew until reading this thread that there were ball bearings under the gib screws. I just had to check both heads to be sure they were there and sure enough, both heads have ball bearings under the gib screws. Who knew....

I have an old Yuasa 2” that I dismantled and cleaned two years ago. Just found the last ball bearing on the floor a couple days ago. I think it returned to earth during the last lunar eclipse. They move through space into another dimension with amazing efficiency.
Amazon was my friend-

 

[ARC-170]

There should be a ball bearing under each of the three gib screws - check again?

Just checked again, and there is nothing there. I didn't drop any when I took this apart, either. It looks like the gib screws were removed and moved around at one point because the longer gib screw was in one of the shallower holes. Given that two of the set screws that lock the bit in place were gone, I'm not surprised this is missing pieces. But, I never would have known, so thank you for pointing this out. I really appreciate it.

The ID of the threaded hole is 0.154". They have 5/32 steel balls at the local big box store, which are too big (0.156"). They are about $4 for just one. McMaster has 9/64" (0.141") diameter balls, but I have to buy 100. They are about $6 for all 100. I'm going to check the local hardware store and see what they have.

 

[ARC-170]

I have an old Yuasa 2” that I dismantled and cleaned two years ago. Just found the last ball bearing on the floor a couple days ago. I think it returned to earth during the last lunar eclipse. They move through space into another dimension with amazing efficiency.
Amazon was my friend-

They go the same place as 10mm sockets and socks from the dryer.

 

[jbaccell]

I thought someone wrote that they were 1/8" balls?

 

[ARC-170]

I thought someone wrote that they were 1/8" balls?

That might have been me. I just looked though; when I measured, the holes were 0.154". They make 9/64" balls, so those should work. I'm going to take the head to the local hardware store and see what they have. 1/8" might work as well.

 

[Ken from ontario]

That might have been me. I just looked though; when I measured, the holes were 0.154". They make 9/64" balls, so those should work. I'm going to take the head to the local hardware store and see what they have. 1/8" might work as well.

As far as I remember they are 3mm chrome plated steel balls.
Correction on the size was just made.

 

[Ken from ontario]

I just went to my shop and checked the size, it's 3mm and not 4mm. I'm sorry about giving bad info,