Making and measuring small holes (<8mm)

[WobblyHand]

Reamers are good for their intended purpose but they have two limitations. First; They will only created the size hole they were made to create. And more importantly, they will follow the hole. Ream a crooked drilled hole and you'll get a crooked reamed hole. Only by boring can you make straight concentric hole that is any size you need it to be.

Yes, but there are limitations with boring as well. If the boring bar is narrow compared to the hole depth one can have some errors due to bar deflection. (I learned that the hard way.) Carbide bars deflect less than steel, but for length to width ratios greater than 6:1, even carbide deflects. 10:1 and higher ratios are tough. Long skinny precise holes are not easy. Possible with good techniques, but it takes a bit of skill.

Need a precise hole, drill to remove the bulk, then bore. Possibly ream at the end. I have found that boring with a sharp insert (0.002" Nose radius) gives really nice precise results. I'm forever in gratitude for Mickey's tutorial on boring. Learned a whole lot from him. RIP.

 

[Janderso]

Great, more tools that I didn’t realize that I should have on hand for that time in the future I might actually need it.
Then do I get two sets, one for my home shop toolbox, and one for my work tool box. Decisions, decisions…

Unfortunately, the four pack was $9.89 in my cart. Guess they know that they have me on the hook already, and do not need to entice me with the super cheap intro deals.
But, I’ll probably go with the 10 piece set for $24 anyways.

One thing nice about building up my home retirement shop, while still working, is my budget is a bit more flexible now. When I retire, if I ever do, ( hopefully slow down quite a bit at least, I figure I will work til the day I die) my budget will be going on a huge diet.


Sent from my iPhone using Tapatalk

After the first $50,000 it gets much easier.

 

[Janderso]

Yes, but there are limitations with boring as well. If the boring bar is narrow compared to the hole depth one can have some errors due to bar deflection. (I learned that the hard way.) Carbide bars deflect less than steel, but for length to width ratios greater than 6:1, even carbide deflects. 10:1 and higher ratios are tough. Long skinny precise holes are not easy. Possible with good techniques, but it takes a bit of skill.

Need a precise hole, drill to remove the bulk, then bore. Possibly ream at the end. I have found that boring with a sharp insert (0.002" Nose radius) gives really nice precise results. I'm forever in gratitude for Mickey's tutorial on boring. Learned a whole lot from him. RIP.

You are preaching to the choir.
I have struggled with a taper while boring until I figured out it was deflection.
A lesson I learned as well.
Wobbly, you got this man.

 

[epanzella]

Enter the God of skinny holes. The spring pass.

 

[Parlo]

If you don't have a reamer.
Stone a small radius on the corners of both of the cutting edges on a twist drill to cut nearer the drill size when opening out a hole.

For your 6mm hole, use a piece of 6mm steel & polish a slight taper a few thou under at the end. The further into the hole it goes the nearer the size you get. No accurate machining required for the gauge.