Boring Noise & Finish

[Roger B]

Some interesting experiments   

Another option for small holes is to use an end mill as a boring bar. I set the cutting edge level and on centre height.

[Vixen]

What is the diameter of the finished hole? Is it still the 10mm diameter that caused the original problem, or larger?

Mike

[PaulR]

Some interesting experiments   

Another option for small holes is to use an end mill as a boring bar. I set the cutting edge level and on centre height.

That would seem to be a very rigid alternative but it begs some questions!...

1 Does it give a good finish?
2 It looks like you've got it in a square holder, is that right?
3 What sort of depth of hole could you get with a 6mm end mill?
4 Would a starting hole of say 7mm suffice?

[PaulR]

What is the diameter of the finished hole? Is it still the 10mm diameter that caused the original problem, or larger?

Mike

I started with a 10mm hole (max size in tailstock chuck). I mentioned earlier in the thread that I made a mistake in the OP - it's a 6mm bar not 8mm so a starter 10mm hole should be ok. I didn't measure the final hole, I just kept cutting until I achieved a decent finish as it was just an experiment on some scrap... which has been returned to the scrap bin as I'm sure I'll find a use for it 

[Roger B]

That would seem to be a very rigid alternative but it begs some questions!...

1 Does it give a good finish?
2 It looks like you've got it in a square holder, is that right?
3 What sort of depth of hole could you get with a 6mm end mill?
4 Would a starting hole of say 7mm suffice?

I have used this technique successfully and got a good finish in holes from 3mm diameter upwards. I got the idea from Jo or Jason, I don’t remember who.

I have a square holder for 6mm diameter shanks that came with a set of HSS boring bars and a homemade rectangular holder for 3mm shanks.

I am not sure how deep I have gone, maybe 15mm, but this was limited by the size of the job not the technique. The cutter needs to be offset a few degrees so that only the tip will cut.

7mm would work with a 6mm end mill. I always remove as much as possible by drilling.

HSS end mills will be less likely to chip or break than carbide however I use Proxxon carbide end mills for 2 and 3mm cutters as they have 3mm shanks and are easier to use in small spaces.

[PaulR]

That would seem to be a very rigid alternative but it begs some questions!...

1 Does it give a good finish?
2 It looks like you've got it in a square holder, is that right?
3 What sort of depth of hole could you get with a 6mm end mill?
4 Would a starting hole of say 7mm suffice?

I have used this technique successfully and got a good finish in holes from 3mm diameter upwards. I got the idea from Jo or Jason, I don’t remember who.

I have a square holder for 6mm diameter shanks that came with a set of HSS boring bars and a homemade rectangular holder for 3mm shanks.

I am not sure how deep I have gone, maybe 15mm, but this was limited by the size of the job not the technique. The cutter needs to be offset a few degrees so that only the tip will cut.

7mm would work with a 6mm end mill. I always remove as much as possible by drilling.

HSS end mills will be less likely to chip or break than carbide however I use Proxxon carbide end mills for 2 and 3mm cutters as they have 3mm shanks and are easier to use in small spaces.

Thank you Roger, that's very helpful, I'll pick up an end mill and give it a try.