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Deep Boring Holes

ThatGuysFarm

Plastic
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Nov 28, 2023
I am needing to bore holes in a 15" DOM tube. We have been boring these out on a lathe and then weld them to the part. I'm wanting to set the entire part up in a large boring machine to get the ends both bored in line with each other. I'm looking for ideas, or setups that others have did. The DOM tubes ID starts about 2" and we are boring it out to 3.1" and its 14.875" long. The first picture is the Boss and the second picture is the entire assembled part. The complete part is about 87" long.
PG34 03-2 0006 Link Boss.pngPG29A-ForumPic.png
 
A fixture on a boring mill with enough travel will do it. If it has a big enough rotary table, you can go from both sides and have a boring bar half as long.

Yep that's what I do using my horizontal boring mill. Perfect machine for the job.

I did this recently making a rudder tube. Stainless weldment, flanges, drilled holes etc then on the HBM to bore the ends coaxial for the bushes. Quite straightforward.

PDW
 
Rotary table on an HBM and bore from both ends; or line bore if you don't have a large rotary. Could probably poke it through from one end with the right single-ended bar and tool geometry, but if you don't know how to do this already, you might find it taxing.
 
Drill it out then bore the last 20 thou or so with 3" Devlieg bar using cartridge insert.

I would bore from one side at that length to Dia ratio.
 
Can you rough the bores on the lathe first? Seems like that would be a lot faster than using a boring mill to rough them. Then again I haven't seen a boring mill operate in 20 years and those were super old DeVlieg's at the time.
 
I am needing to bore holes in a 15" DOM tube. We have been boring these out on a lathe and then weld them to the part. I'm wanting to set the entire part up in a large boring machine to get the ends both bored in line with each other.
Five'll getcha ten that at the price of tubing, you can bore the whole thing in a lathe from solid and come out ahead. No reason not to stick with doing it in a lathe unless you are trying to get away from weld distortion.

Even if that's the case I'd still make the tube instead of buying it, then maybe a finish pass in an hbm or even a portable boring machine. Or just a hone after welding should make it all back to round. Making your own tube is going to be cheaper and easier to get.
 
I don't know the tolerances allowed, but boring from both ends never seems to be worth it....the two halves won't be the same and if they are .... you spent a ton of time making them the same and that's money. Bore from one side only IMO.
 
I don't know the tolerances allowed, but boring from both ends never seems to be worth it....the two halves won't be the same and if they are .... you spent a ton of time making them the same and that's money. Bore from one side only IMO.
That is true. But since he said size isn't an issue, he might be able to bore from both sides and then run a ream thru it.
 
Yep that's what I do using my horizontal boring mill. Perfect machine for the job.

I did this recently making a rudder tube. Stainless weldment, flanges, drilled holes etc then on the HBM to bore the ends coaxial for the bushes. Quite straightforward.

PDW
Do you have any pictures of your setup? Sounds slick
 
Can you rough the bores on the lathe first? Seems like that would be a lot faster than using a boring mill to rough them. Then again I haven't seen a boring mill operate in 20 years and those were super old DeVlieg's at the time.
Right now we are lathing the bores before welding them onto the part. It is working fine, but I would like to bore it on the part so the bores on both ends and 100% square. The bore on the one end goes to a large ball bushing that has 20 degrees of motion both ways so there is some forgiveness there since in the real world when the arm is moving it should never move more then 8 degrees, but I always want to improve on the process and make it the best we can.
 
to get the ends both bored in line with each other.
This here is going to be the slightly challenging part. Either need to find a way to line up off the side of the part for each end or an HBM with more than 87” X travel. Neither is much difficulty to overcome. Boring the DOM end would be no big deal.
 
Another option for finishing is a shell reamer. If there's a bunch to do, she'll reamer would be the way to go.
 
I would either buy the tubing closer to size, or drill from solid and rough it from both ends like has been said. Plenty of choices to remove the last 1/16" from the bore depending upon available tooling or what you are willing to spend on tooling.
 
Five'll getcha ten that at the price of tubing, you can bore the whole thing in a lathe from solid and come out ahead. No reason not to stick with doing it in a lathe unless you are trying to get away from weld distortion.

Even if that's the case I'd still make the tube instead of buying it, then maybe a finish pass in an hbm or even a portable boring machine. Or just a hone after welding should make it all back to round. Making your own tube is going to be cheaper and easier to get.


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
 
Yup, even on manual machines I don't bother getting quotes on tubing anymore.
The last few quotes were $10+/lb for 1026 tube, and $1.86/lb for 4140 solid bar.

I'd rather pay myself $300 to make a 4"d x 6" long hole than pay the metal man.
 
I just ran some 2-5/8" x 1/4" wall DOM.
That was the first DOM that penciled out to bother buying tube in a long time!

We make a LOT of tubing here! (from solid)
I can always make a good rate drilling solid bar.
I despise dooing $2 work to $5 material.
The other option is dooing $5 work to $2 material.
Finished part costs the same .. well ... actually it doesn't, b/c I would charge at least $3.5-$4 even for that $2 of work if the ratio was that bad, so ...

Besides, you can count on being able to git solid a whole lot more than that tube size!


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Think Snow Eh!
Ox
 
There are times when it makes sense and times when it doesn't. That's what experience will teach you. I used to use a few specialty suppliers that had really good prices for tubing, but I'm pretty much out of the purchasing game these days.
 
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
 








 
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