Boring a Deep Hole

[PixMan]

Doing this on a mill with a boring head is certainly going to be "less risky" Ed. The piece can be done on a lathe, though you'll be running slow (under 500 rpm) to keep it from moving. There's going to be vibration from the out of balance condition.

What I forgot to ask is how many of these do you need to make? That's a big part of the decision too.

If you do this in the mill, do you have a boring head? If so, what diameter shank does that boring head use?

[EdK]

(07-17-2013, 06:23 AM)PixMan Wrote: Doing this on a mill with a boring head is certainly going to be "less risky" Ed. The piece can be done on a lathe, though you'll be running slow (under 500 rpm) to keep it from moving. There's going to be vibration from the out of balance condition.

What I forgot to ask is how many of these do you need to make? That's a big part of the decision too.

If you do this in the mill, do you have a boring head? If so, what diameter shank does that boring head use?

Ken,

I like the "less risky" aspect. I will be making one of these, assuming I don't screw up the first one.

I do have a 2" boring head. It takes 1/2" shank boring bars.

Ed

[TomG]

Ed,

That part isn't too long to just grab with a four jaw. Save the change of underwear for your boring adventures.

Doing it in the mill would require a larger boring head. If you tried doing it with a 1/2 bar and if you could find one long enough, it would probably sing like the church choir. A boring bar held in the lathe would be a lot more rigid.

Another option, just because there are many ways of doing this, would be to mount the block on a faceplate in the lathe. That would be even more rigid than a four jaw, and you could couterbalance it. Just a thought.

Tom

[PixMan]

Tough decision tree there Ed. I believe you should first try the mill, at least get the hole started that way.

Of course the lathe allows you use a larger boring bar, but that rigidity is lost when you have a workpiece flopping around.

I have had pretty good success over the years using boring bars that are larger then turned down for a short length to fit into a boring head. I agree that you really should have a 3" or 4" boring head that takes at least 3/4" bars. Check this photo and see the long bar in the middle with a turned down end. That bar has a 3/4" end diameter which fit into my crappy Chinese boring head and holds a 1/4" HSS or brazed carbide bit.



You want something similar. It's a quicky to make Ed, and cheap. Use the 1144 material you got.

[EdK]

(07-17-2013, 06:44 AM)TomG Wrote: Ed,

That part isn't too long to just grab with a four jaw. Save the change of underwear for your boring adventures.

Doing it in the mill would require a larger boring head. If you tried doing it with a 1/2 bar and if you could find one long enough, it would probably sing like the church choir. A boring bar held in the lathe would be a lot more rigid.

Another option, just because there are many ways of doing this, would be to mount the block on a faceplate in the lathe. That would be even more rigid than a four jaw, and you could couterbalance it. Just a thought.

Tom

I've been wanting to get a 3" boring head for quite some time now so maybe this is the justification I need to finally pull the trigger. A 3" boring head takes 3/4" shanked boring bars thus reducing the choir decibels.
The faceplate idea is not a bad option also.

Thanks Tom!

Ed

[PixMan]

Strapping it to faceplate is good, though I find you never seem to have slots or fixing points in just the right place.

Funny is that I've got a 15" face plate in integral D1-6 mount which has never been mounted to the spindle. It still has the cosmolene on it.

The problem with a faceplate mounting is that you often add at least 1xD more to your boring bar length to get past the clamps.

[EdK]

(07-17-2013, 07:00 AM)PixMan Wrote: Tough decision tree there Ed. I believe you should first try the mill, at least get the hole started that way.

Of course the lathe allows you use a larger boring bar, but that rigidity is lost when you have a workpiece flopping around.

I have had pretty good success over the years using boring bars that are larger then turned down for a short length to fit into a boring head. I agree that you really should have a 3" or 4" boring head that takes at least 3/4" bars. Check this photo and see the long bar in the middle with a turned down end. That bar has a 3/4" end diameter which fit into my crappy Chinese boring head and holds a 1/4" HSS or brazed carbide bit.

You want something similar. It's a quicky to make Ed, and cheap. Use the 1144 material you got.

Ken,

Not a bad idea. I think you and Tom have hit on a good strategy to use the mill with a boring head suitable for the task. The quill stroke on my mill is rated at 5" but I'll need to verify that. I can always lower the head for the last bit if necessary.

Thanks guys!

Ed

[TomG]

Ken,

I have a faceplate that is littered with 5/16-18 tapped holes that works great for stuff like this, as you say the slotted type can definitely be a pain. It sounds like Ed needs to buy a new boring head.

Tom

[doubleboost]

You could always mount the job on the lathe cross slide and put the boring bar between centres
This is how I bore my engine cylinders
Use a big drill from the headstock first










John

[EdK]

(07-17-2013, 02:54 PM)doubleboost Wrote: You could always mount the job on the lathe cross slide and put the boring bar between centres
This is how I bore my engine cylinders
Use a big drill from the headstock first

John

Hi John,

I thought of that also. Isn't that called line boring?

I wondered how well it would work on a 1.5" hole. I thought that size hole might be too small for line boring, but I don't know.

Ed