Deep Boring Holes

[ThatGuysFarm]

Does the bore need to be only at the ends or is it needed for the full length. Folks seem to assume the accurate bore needs to be full length for some reason. Easier if the middle is hogged out roughly a bit over size as long as you have good collars at each end.
BilLD

It needs to be full length for a pin. At least on the 15" bore.

 

[Ox]

It needs to be full length for a pin. At least on the 15" bore.

Your terminology and my ears (and likely most here) are at odds.

A 15" bore, is a hole that is 15" in diameter.

Per your drawing in post #1, you are apparently referring to a 3.1" bore that is 15" through.


The bore of a 350 Chivy is not 3.48".



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Think Snow Eh!
Ox

 

[Zeuserdoo]

What tolerance is on the bore, and what is the surface finish requirement?

 

[ThatGuysFarm]

Your terminology and my ears (and likely most here) are at odds.

A 15" bore, is a hole that is 15" in diameter.

Per your drawing in post #1, you are apparently referring to a 3.1" bore that is 15" through.


The bore of a 350 Chivy is not 3.48".



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Think Snow Eh!
Ox

Sorry my bad on terminology, Yes I was talking about the 3.1" bore that is 15" deep through the part. It should be 3.1" the entire length.

 

[Mtndew]

Sorry my bad on terminology, Yes I was talking about the 3.1" bore that is 15" deep through the part. It should be 3.1" the entire length.

It's ok we knew what you meant.

 

[Ox]

Absolutely!
Start from solid all day long!

A) Order up some Hot Rolled bar
B) While you are waiting on that, call Allied and tell them what you are dooing, and they will set you up with the proper tooling to knock that out a lot quicker than a boring bar! Roughing from both sides may be a good plan.
C) Finish from one side with a 2.5" De-Vibe bar.

You just saved $50/part compared to what you were gunna doo!


Now - your post eludes to there being 2 tubes on a weldment, and in that case, I understand your wanting to hit it on a HBM. I have no experience with boring that L/D on a mill, so IDK if that is a good plan or not. But it will certainly cost a boat load more than just finishing it in the lathe. Maybe better to invest in more better welding fixtures?


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Think Snow Eh!
Ox

Note:

When I mentioned contacting Allied, I mean that they have ways to git to 3.1" that is easier than a spade drill.
They can knock that out purty quick with some newer type tools, so call them and ask...


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Think Snow Eh!
Ox

 

[StinkyDan]

Cheaper option than a boring mill might be hanging it off the side of the table on a radial drill and using drills and a reamer, if the size is important. If u have 2 bores on one part that need to be in line w each other, then u could bore one, make a pin that size, bolt the pin to ur table and put the bored end on that, locate on that pin vertically inside the bore, then when u cut the other bore they'll be in line.

 

[ThatGuysFarm]

I priced out solid stock vs DOM. The C1018 6" solid is about 20% more then the DOM. I'm starting to lean toward drilling the hole in the DOM with a 3-1/16" drill bit. I talked with engineer and he is ok with the 3.0625" instead of 3.1". Anyone have experience with these big drill bits and what kind of tolerances/finish do you get with them? I've never been around them. Thanks

 

[Ox]

Wow - I'm surprised that those are that close in cost!

You are talking about "multi-insert" drill here correct?

I have a 3" and a 3.5" I think, but it's actually been a few years since I have used either, but not much to talk about that I can think of, as long as you have enough machine behind it.


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Think Snow Eh!
Ox

 

[ThatGuysFarm]

Wow - I'm surprised that those are that close in cost!

You are talking about "multi-insert" drill here correct?

I have a 3" and a 3.5" I think, but it's actually been a few years since I have used either, but not much to talk about that I can think of, as long as you have enough machine behind it.


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Think Snow Eh!
Ox

I was looking at large twist bits, but I'm open to ideas. Would be great to get a good enough finish in one pass!

 

[Ox]

I was looking at large twist bits, but I'm open to ideas. Would be great to get a good enough finish in one pass!

You can't be serious?
Can you even buy such a thing today?
Regardless, DON'T go that route!

Here is my 3.5" drill.
Looks like it lost an insert the last go.
This one would drill 1/2 of your part at a time.
3" shank I think.





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Think Snow Eh!
Ox

 

[ThatGuysFarm]

You can't be serious?
Can you even buy such a thing today?
Regardless, DON'T go that route!

Here is my 3.5" drill.
Looks like it lost an insert the last go.
This one would drill 1/2 of your part at a time.
3" shank I think.

View attachment 418833



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Think Snow Eh!
Ox

Pardon Our Interruption

This is the one that got me thinking about it. If we can't make a full pass I'm not sure if it would be worth while changing up our current setup. I've never been around bits these big so i don't know.

 

[gbent]

Do I have these right, you are buying 6" tubing, 2" wall, and boring to 3.1? Why not start with something closer to finish size?

 

[ThatGuysFarm]

Its 6"x2" DOM, 6" OD x 2" ID. We have been getting that because it is a "stock" size from our steel vendor.

 

[Ox]

Well, a 1.5" wall would leave you with just running a de-vibe boring bar down-hole.
Material prolly wouldn't be any cheaper, but ...

On the other hand, if you are getting DOM for only $20 more than solid, you are obviously getting some really cheap DOM (India) so you are gunna take what you can git.

I had a job a few years ago that we bored out some 4.5 and 5" DOM to just over 3" as well as it had 1/4" (?) too much wall. Those parts were 3' long tho.


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Think Snow Eh!
Ox

 

[Mtndew]

Pardon Our Interruption

This is the one that got me thinking about it. If we can't make a full pass I'm not sure if it would be worth while changing up our current setup. I've never been around bits these big so i don't know.

If you're going from 2" to 3-1/16" get a 3 or 4 flute drill if you can.

 

[ThatGuysFarm]

Well, a 1.5" wall would leave you with just running a de-vibe boring bar down-hole.
Material prolly wouldn't be any cheaper, but ...

On the other hand, if you are getting DOM for only $20 more than solid, you are obviously getting some really cheap DOM (India) so you are gunna take what you can git.

I had a job a few years ago that we bored out some 4.5 and 5" DOM to just over 3" as well as it had 1/4" (?) too much wall. Those parts were 3' long tho.


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Think Snow Eh!
Ox

No the DOM is 20% cheaper than solid. 4' DOM is around $1000 and 4' of 6" solid is around $1200. Its from an American mill, at least that's what the supplier tell me.

 

[Ox]

6" HRR 1018 should not be more than $100/foot at any volume.

Are you just buying 4'?
I was under the impression that you had many of these to run.
Shirley you wouldn't be gitting this deep into the weeds over 3 pcs?


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Think Snow Eh!
Ox

 

[Ox]

If you're going from 2" to 3-1/16" get a 3 or 4 flute drill if you can.

Known as a "Core Drill".
They still make those?
I s'pose the doo, but you likely have to look harder than 30 yrs ago.


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Think Snow Eh!
Ox

 

[ThatGuysFarm]

6" HRR 1018 should not be more than $100/foot at any volume.

Are you just buying 4'?
I was under the impression that you had many of these to run.
Shirley you wouldn't be gitting this deep into the weeds over 3 pcs?


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Think Snow Eh!
Ox

I was pricing to compare apple to apples basicly, we are doing on average 1.5 of these bores a week in production.