Inside boring and threading
- Thread starter adamsgt
- Start date
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mike in co
Guest
short holes can be done with std tooling, boring bars for depth, inside threading tools for threading....they all fit your quick type change holders. bigger boring bars have special holders.( pre bore with a drill bit, bore to finished size)
typically you thread on the "front" side of the material,
there are guys that turn thier tools over and thread on the backside so they can see better.
micro makes nice cutters, grind your own, and then there are inserts.
typically you thread on the "front" side of the material,
there are guys that turn thier tools over and thread on the backside so they can see better.
micro makes nice cutters, grind your own, and then there are inserts.
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JerrySharrett
Senile Member
Two major differences in inside vs outside 1) you can't often see your stopping place, so make allowances like a dead-stop, digital readout, groove, etc. and 2) ID machining requires much more heel clearance on the tool you are using.
adamsgt
Jerry Adams
Just to make sure I understand that. Depending on the size of the cutting bit, the depth of the thread and the inner diameter of the workpiece, the bit could rub before reaching the bottom of the desired thread?
Mike. who is micro?
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mike in co
Guest
"micro 100"..do a google search or your local/online machine tool supplier.
lots of carbide cutters, some solid carbide.
lots of carbide cutters, some solid carbide.
JerrySharrett
Senile Member
If the heel clearance is insufficient, the tool will rub instead of cut EVEN at the top of the thread. A simpler to see thing about internal machining is tool overhang.
On OD machining it is easy and prudent to keep tool overhang to a minimum, on ID machining the tool must overhang enough to reach the desired depth. This means that depth of cut and feedrate must be greatly reduced.
All this stuff is easy to see after you think about it. It's just starting out, some things are not seen that may be critical to the desired outcome.
adamsgt
Jerry Adams
I guess I was being somewhat vague to entice a larger scope of responses. I have the latest MSC flyer and saw some Accupro solid carbide internal threading tools. These appear to be self-explanatory as each size tool has a specific range of threads it will cut. I also seem to remember something about indexable threading tools and here I think I know enough to be incredibly dangerous. My experience so far has been to grind and use square HSS lathe bits for external turning and facing. I know pretty much nothing about all these different cutting inserts and their associated holders, indexable or otherwise . Maybe all I can hope for at this time is a pointer to some source documents I could use to educate myself on the use, care, and feeding of these instruments.
Mike, googled micro 100 and got a lot of hits. Travers had lots of info, thanks for the tip. Interesting how "google" has become an acceptable verb.
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mike in co
Guest
std right hand threads are typically cut with the lathe runing "forward", and left hand done in "reverse"
a ground tool held in a boring bar can be used to cut internal threads.
a "fish" ...60 degree alignment tool is almost required. on internal threads i always feed straight in, but on external i often do a 29/30 degree feed.
get a chunk of alluminum and practice, then do the same with a chunk of the material you plan work on.......practice, like in shooting tends to produce a better end product.
i measure and mark "S" start, "F" finish on my handwheels....if you have done external, have you practiced stopping at a specific point.....its not hard, and necessary on some internal threading....
mike in co
a ground tool held in a boring bar can be used to cut internal threads.
a "fish" ...60 degree alignment tool is almost required. on internal threads i always feed straight in, but on external i often do a 29/30 degree feed.
get a chunk of alluminum and practice, then do the same with a chunk of the material you plan work on.......practice, like in shooting tends to produce a better end product.
i measure and mark "S" start, "F" finish on my handwheels....if you have done external, have you practiced stopping at a specific point.....its not hard, and necessary on some internal threading....
mike in co
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Adam
I have a few small accupro solid carbide boring bars and have been very happy with them.
I also have a couple small boring bars of another brand (possibly circle but I don't recall for sure at the moment)that according the MSC item description are solid carbide but actually have a cement insert. They are functional but I prefer the accupros.
James
I have a few small accupro solid carbide boring bars and have been very happy with them.
I also have a couple small boring bars of another brand (possibly circle but I don't recall for sure at the moment)that according the MSC item description are solid carbide but actually have a cement insert. They are functional but I prefer the accupros.
James
Randy Perkowski
New member
ID Boring And Threading
I will usually use the largest boring bar that fits into a hole for both boring and threading. The biggest issue with ID work is getting clearance for the the bar, any clamping hardware on the bar, and not running into the face of the part on blind holes. A slightly above center condition usually stops any insert interference in bores. For small hole threading I use a triangular, 1/4" I.C, (inscribed circle) insert with (3) cutting edges, and a bar that gives ample room to pull out of the cut at proper depth.
When cutting into a shoulder where a relief groove is acceptable, I will sometimes use a left hand threading bar and start the tool in the relief groove and chase the tool out of the part. The lathe is set to run in reverse (clockwise) This produces a right hand thread and takes away the problems associated with crashing the bar and insert into your part. A positive stop on the carriage is used to find the relief groove for the remaining passes.
I will usually use the largest boring bar that fits into a hole for both boring and threading. The biggest issue with ID work is getting clearance for the the bar, any clamping hardware on the bar, and not running into the face of the part on blind holes. A slightly above center condition usually stops any insert interference in bores. For small hole threading I use a triangular, 1/4" I.C, (inscribed circle) insert with (3) cutting edges, and a bar that gives ample room to pull out of the cut at proper depth.
When cutting into a shoulder where a relief groove is acceptable, I will sometimes use a left hand threading bar and start the tool in the relief groove and chase the tool out of the part. The lathe is set to run in reverse (clockwise) This produces a right hand thread and takes away the problems associated with crashing the bar and insert into your part. A positive stop on the carriage is used to find the relief groove for the remaining passes.
Wayne Shaw
Active member
Randy is right on. If at all possible, I inside thread from the inside out, in reverse. The set up he describes is right too. IMHO.
The first time I made internal threads, I read the instructions in the machining book, and then ignored them. I figured I was smart enough to figure it out.
The threads would not fit.
I had made left hand threads.
It turns out that is common. Guy thinks he is smart, but gets left hand internal threads the first time.
What does it all mean?
I should have followed instructions.
The threads would not fit.
I had made left hand threads.
It turns out that is common. Guy thinks he is smart, but gets left hand internal threads the first time.
What does it all mean?
I should have followed instructions.
JerrySharrett
Senile Member
Real men don't follow instructions. Women lay everything out in order then read the instructons. BALONEY!!