# How do I drill small holes straight? (I made a suppressor adapter)



## strantor (Feb 10, 2020)

A friend brought me this cheap little .22lr pistol, wanted me to come up with a way to adapt a suppressor to it. This is what I came up with. Turned down the end of the barrel and threaded it 7/16-20, then made this adapter with a 7/16-20 internal thread and a 1/2-28 outer thread. Worked well, after going through 4 failed blanks where the bore was crooked. Drill bit wander. How do I get better than a 20% success rate? I have somehow avoided learning this lesson; everything I've drilled/bored thus far has been larger diameter. The bigger bits don't wander as bad, and I'm usually going in with a boring bar afterwards anyway so it doesn't matter. I plan to do this again and I want to do it better, more predictable outcome. Is there a different tool I should be using other than a drill bit? I know a better ground drill drills a straight_*er*_ hole but what drills a *straight* hole?


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## GL (Feb 10, 2020)

1.  I like stub length drill bits, less deflection.  2. Bore the hole - less wonder, but you have to start with a hole so .22+a little is a small boring bar (assuming that is the wonky hole) 3. As you suggested, good grind helps a lot. This also assume your lathe is all squared up and wants to drill straight holes, sometimes they don't, which is a PITA but fixable usually.


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## graham-xrf (Feb 10, 2020)

I once came across one of these among a flea market batch of stuff. It was about 5" long, and at first I did not know what it was. Turns out it is called a "gun drill", for the obvious reason.




It still lurks somewhere lost in the garage. There is something about the cut in the end that makes it able to drill deep holes without wandering off, provided you keep blowing air or pumping liquid up it up it to clear the swarf.

The wiki explains it. These are not so common as regular spiral flute drills, so I would guess they might be expensive. If I can find it again, and it happens to be 0.22", you are welcome to it gratis. From memory, it might be about that size.

https://en.wikipedia.org/wiki/Gun_drill


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## GunsOfNavarone (Feb 10, 2020)

I'm all about this subject...don't get me wrong...but can you even do more than hypothetically discuss this subject? If nothing else, I've had far larger drill bits wander even after a spot drill... interested in the problem.


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## graham-xrf (Feb 10, 2020)

The wiki mentions drill-to-diameter ratios of 90:1 and 300:1
If there is any run-out at all, it will tend to flex the end. The article does mention that on lathes, it is practical for hole depths less than 50mm, but does not say why. I just followed some of the references - and got distracted!

Looking at it, it would seem that it has a single cutting edge, and then quite a large fraction of the remaining circumference is devoted to being a perfectly round guide, and that "round guide" extends back a little before it gets to the rod relief. This I get from looking at the close-ups of the business end.

--> LINK


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## strantor (Feb 10, 2020)

graham-xrf said:


> I once came across one of these among a flea market batch of stuff. It was about 5" long, and at first I did not know what it was. Turns out it is called a "gun drill", for the obvious reason.
> 
> View attachment 313276
> 
> ...


 There you go, gun drill! This has the faint odor of something I once knew, long since triaged in favor of other information. Yeah, I don't have any gun drills. Looking at them online now. You're correct, they're not cheap or easy to find. I haven't found exactly what I'm looking for and when I do, I estimate it will be around $75 (+/- $25) so if you've got one you don't need or want, I would gladly lighten you load. I appreciate the offer. 

P.s. it doesn't need to be exactly .22 for what I'm doing. Anything between .22 and roughly .30 would work to make this adapter. Just as long as it makes a straight hole, I can work with it.


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## strantor (Feb 10, 2020)

GunsOfNavarone said:


> I'm all about this subject...don't get me wrong...but can you even do more than hypothetically discuss this subject? If nothing else, I've had far larger drill bits wander even after a spot drill... interested in the problem.


Are you saying it's against the laws of physics to drill a straight hole, or that it's against the rules of the forum (and possibly local governments) to discuss gunsmithing?

In the case of the former, there's always the "there's no such thing as a perfect circle" argument which holds water if we're talking about sub-micron tolerances (which I'm not).

In the case of the latter, I seem to remember there used to be a gunsmithing sub forum here. Am I wrong? Was that another forum? Pretty sure it was here. Did it get taken down? Am I in breach of some new TOS? I'll have to look into that. As far as local gun laws, I only know the ones for my locale, and AFAIK I'm not in breach of those. Note that I did not machine that suppressor; it's a commercial unit. All I did was thread the end of a barrel and machine a thread adapter.


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## MontanaLon (Feb 10, 2020)

For a piece that short, I'd drill it and then bore it with a solid carbide boring bar. 

There is nothing illegal about making an adapter unless it has oil filter threads on one end and then ATF has ruled that is a suppressor itself.


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## graham-xrf (Feb 11, 2020)

strantor said:


> There you go, gun drill! This has the faint odor of something I once knew, long since triaged in favor of other information. Yeah, I don't have any gun drills. Looking at them online now. You're correct, they're not cheap or easy to find. I haven't found exactly what I'm looking for and when I do, I estimate it will be around $75 (+/- $25) so if you've got one you don't need or want, I would gladly lighten you load. I appreciate the offer.
> 
> P.s. it doesn't need to be exactly .22 for what I'm doing. Anything between .22 and roughly .30 would work to make this adapter. Just as long as it makes a straight hole, I can work with it.


This is something I know I have, and it is in there somewhere. For a while at least,  the whole garage, (and everything I play with involving machines), is at present being messed up by a building operation that will create a washing/utility room and hopefully leave me with a nice man-space for my lathe activities. I will have serious look for it, but I don't promise it is not stashed a bit far to get at easily.

Like a gun-drill, a boring bar also cuts at only one place relative to the rest of the machine, and the forces and support are constant direction.

As to ethics, notice that it is not the makers nor users honestly out in the open that are the problem, regardless those who apply laws as if they were the guilty. The bad guys will acquire them anyway, and they won't be on a public forum. Here (UK) one is in serious trouble if anything to do with a handgun, which is seen as having only one possible illegitimate purpose. Strangely, it is however, legal to be a licensed gunmaker, the various goods often for export also. I am not sure the position on handguns specifically.


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## SLK001 (Feb 11, 2020)

It could be your drilling technique.  I start a hole with a center drill that I continue to drill with until I'm as deep with it as I can go.  If the hole is larger than 1/8", I start there.  It's a PITA, because you have to clear it FREQUENTLY.  But this creates a straight hole that I can now put a drill WITH THE SAME DIAMETER as the center and continue drilling.  The hole created by your center will perfectly guide your twist drill and minimize wondering.  Peck drill a hole with no thru pilot.  Clear the bit frequently.  Use adequate oil.  If you need a larger hole, step drill in small increments up to close to your finished size.  Bore to final size, if straight is your goal (and it usually is).

That's the technique I use for drilling (mostly steel).


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## strantor (Feb 11, 2020)

SLK001 said:


> It could be your drilling technique.  I start a hole with a center drill that I continue to drill with until I'm as deep with it as I can go.  If the hole is larger than 1/8", I start there.  It's a PITA, because you have to clear it FREQUENTLY.  But this creates a straight hole that I can now put a drill WITH THE SAME DIAMETER as the center and continue drilling.  The hole created by your center will perfectly guide your twist drill and minimize wondering.  Peck drill a hole with no thru pilot.  Clear the bit frequently.  Use adequate oil.  If you need a larger hole, step drill in small increments up to close to your finished size.  Bore to final size, if straight is your goal (and it usually is).
> 
> That's the technique I use for drilling (mostly steel).


I did use a center drill first. On the first two blanks, just to make a divot to start the twist drill in the center. On the second two, thinking along your same lines, I decided to take the center drill as deep as I could. Broke two center drills. I think I did not evacuate chips often enough and they bound up.


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## strantor (Feb 11, 2020)

GL said:


> This also assume your lathe is all squared up and wants to drill straight holes, sometimes they don't, which is a PITA but fixable usually.


If I suspected my lathe was at fault, how would I confirm/fix?


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## rgray (Feb 11, 2020)

The gun drill will need a hole to enter to work.
I use an end mill for that purpose. stiff and makes straight start hole.
Gun drill machines use a guide bushing for that purpose.
Lathe alignment is still needed as the start hole needs to be straight. The gun drill will follow the start hole and  continue in the same direction.

For doing it with out a straight hole, you could drill the hole then use a tapered mandrel between centers to do the outer machining and threading.
That way the hole is now straight with the body of the part.
You would have to be real sure the part didn't slip on the mandrel. That would make a mess of you're threads.
I use super glue sometimes. It holds well and releases easy with heat. Downside of the releases easy with heat is if you heat it up in the machining process it will release. I use flood coolant to avoid that.
If I don't have the right size mandrel I just make one for the part. But then I have a cylindrical grinder for that.


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## strantor (Feb 11, 2020)

rgray said:


> For doing it with out a straight hole, you could drill the hole then use a *tapered* mandrel between centers to do the outer machining and threading.
> That way the hole is now straight with the body of the part.


I'm glad you mentioned that. I also have been planning to build a spider to align the barrel better, get more accurate threads there, and I've been looking at these range rods to indicate the bore. They are tapered as well. That seems odd to me, as does your suggestion of a tapered mandrel. Why tapered? It seems to me that you want them uniform. it seems to me that a taper would leave room for slop on one end or the other. At the risk of sounding totally stupid and unqualified; the bore of a firearm barrel isn't tapered.... right?


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## nnam (Feb 11, 2020)

I know everyone here are more experienced machining than I am.  But may I add.

Taper probably gives a center alignment, like tail stock center.

You can machine a press fit arbor and press it in to hold if you can make a good straight part for that instead.


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## strantor (Feb 11, 2020)

nnam said:


> I know everyone here are more experienced machining than I am.  But may I add.
> 
> Taper probably gives a center alignment, like tail stock center.
> 
> You can machine a press fit arbor and press it in to hold if you can make a good straight part for that instead.



The difference (as I see it; still waiting for confirmation) between inserting a tapered mandrel into a straight gun bore, and inserting a tapered tool holder into a tapered tailstock is, the tapered tailstock is tapered just like the tapered tool holder. As an extreme example, you know those conical paper cups used at the water cooler or for sno-cones? take one of them and nest into another conical paper cup (tailstock) - self aligning. Now take the paper cup and nest it into a toilet paper roll - self _centering_ on one end, and free to flop around on the other.

I know I'm missing something here; tapered mandrels/range rods wouldn't be the recommended method if I knew what I was talking about. Would like to know where I'm going wrong in the logic.


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## SLK001 (Feb 11, 2020)

strantor said:


> I did use a center drill first. On the first two blanks, just to make a divot to start the twist drill in the center. On the second two, thinking along your same lines, I decided to take the center drill as deep as I could. Broke two center drills. I think I did not evacuate chips often enough and they bound up.



If you broke two center drills, you need to clear the chips more often.  At MAX, you can probably get 0.050" before you need to clear.  I know that it takes time, but it will drill a very straight hole.  It will also provide the guide for the twist drill OF THE SAME SIZE.


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## strantor (Feb 11, 2020)

SLK001 said:


> If you broke two center drills, you need to clear the chips more often.  At MAX, you can probably get 0.050" before you need to clear.  I know that it takes time, but it will drill a very straight hole.  It will also provide the guide for the twist drill OF THE SAME SIZE.


I will try to muster some more patience next time 

But what about one of these options? Might one of them achieve the same straightness with less patience required?






						1/4" Carbide Tipped Die Drill
					






					www.msdiscounttool.com
				









						1/4" Solid Carbide Straight Flute Drill - USA
					






					www.msdiscounttool.com
				









						1/4" Carbide 4F Single End Mill - Extra Long Length
					






					www.msdiscounttool.com


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## rgray (Feb 11, 2020)

strantor said:


> At the risk of sounding totally stupid and unqualified; the bore of a firearm barrel isn't tapered.... right?



My closest mandrel is .2185 on the small end and .2205 on the large end with the tapered part being approx 3 inches long and overall length is 3.75.
The ends are smaller and have a flat for the driving dog.
smallest mandrel I have is .1245 small and .126 large end. Taper on it is 1.9 inch long.
It's a very slight taper and a part that fits wedges on tightly.
It's very easy to miss the size and your part almost tightens up, In that case I have used superglue or built my own mandrel to fit.

I built my first mandrel on my lathe. So don't be afraid to do that.

No taper in barrels.
Range rods I think used to be built with slight taper changing to more taper to wedge in the barrel.
Now (pacific tool) is building them with replaceable bushings on the end. You find the correct bushing that fits your barrel and it goes 
on the end of the rod and when pushed in it bottoms on a slight taper so is centered in the bore.

If you use a mandrel without superglue (or maybe even with) your cutting pressure should be in the direction of forcing the part 
farther onto the taper as opposed to pushing it off the taper.

Purchased mandrels are hardened and may even be HSS . The part is driven onto the mandrel with a deadblow hammer.
Usually I'm driving the mandrel into the part actually.


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## pacifica (Feb 11, 2020)

strantor said:


> A friend brought me this cheap little .22lr pistol, wanted me to come up with a way to adapt a suppressor to it. This is what I came up with. Turned down the end of the barrel and threaded it 7/16-20, then made this adapter with a 7/16-20 internal thread and a 1/2-28 outer thread. Worked well, after going through 4 failed blanks where the bore was crooked. Drill bit wander. How do I get better than a 20% success rate? I have somehow avoided learning this lesson; everything I've drilled/bored thus far has been larger diameter. The bigger bits don't wander as bad, and I'm usually going in with a boring bar afterwards anyway so it doesn't matter. I plan to do this again and I want to do it better, more predictable outcome. Is there a different tool I should be using other than a drill bit? I know a better ground drill drills a straight_*er*_ hole but what drills a *straight* hole?


I've good success with a gun drill, (try ebay for good deals) also start with a spot drill _and drill from both ends_ to control deviation and drift.
If you put the drill in your tool post holder you can perfectly center it on the hole you want drilled(don't trust your tailstock for precision).
Under drill by .01 and ream to desired diameter if you don't want to use a boring bar.


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## mikey (Feb 11, 2020)

Late to the party but I had some thoughts.

Without question, if the hole has to be sized precisely and have straight sides and a clean finish, the best way to do that is to bore it. It's not clear to me from your post but how big is the bore? If it is close to 0.200" ID then a 3/16" solid carbide bar with an insert with a small nose radius will do it, provided the bore is not more than about 1.875" - 2.00" deep. It is also possible that Micro 100 may have a solid carbide boring bar that will do it.
If you have a good twist drill, you can follow it with a good reamer. A reamer can straighten a hole that is not out more than 0.005" so it's possible that a reamer might do it. If you try it and it works, the advantage is that you can make a lot of parts just like it faster than with any other method.
Similar to a gun drill, D-bits, made from hardened and tempered drill rod, are known to drill straight, precise holes. I haven't tried them myself but I will when the need arises. These are what were used back in the old musket days and sounds like a very good solution. Plus, its cheap! Tons of info on D-bits on the net.


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## graham-xrf (Feb 11, 2020)

strantor said:


> If I suspected my lathe was at fault, how would I confirm/fix?


Step 1 is to dial indicate the outside of your chuck relative to the bed (checking the spindle).

Step 2 is to dial indicate to a drill, or ground bar known to be straight, a test bar, whatever, ( checking the chuck).
  If the chuck was 4-jaw - this may be not be relevant.
Find out if there is wobble on round reference stuff put in the chuck.

Step 3. Set up a centre in the chuck, and deliberately turn a fresh point onto it. That will automatically be on the spindle axis. Put another centre in the tailstock, and bring up the tailstock to try and touch the points together.
Use a small steel rule, or metal shim strip, and try and gently grip it between the centre's points.
If it is misaligned even slightly , the strip will tip in a very obvious way.

Step 4. Even the centres are aligned, the axis through the tailstock might be tilted. To check this requires a test bar set into the tailstock, checked with a dial indicator set up on the carriage, and moved along both the side of the test bar, and along the top of the test bar.

So far, this is about the "confirm" part.
The "fix" part depends on what you find. There is tons of stuff on this forum about that. Pretty much all of it involves swallowing hard and reaching for a stiff drink at some stage as you read through it

I would think there are plenty of ways to be breaking drills, or making messed up holes by technique, even if the lathe is perfect!


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## GunsOfNavarone (Feb 11, 2020)

@strantor  I ani't saying/suggesting anything. I'm reading about machinist disscusing the physics of making a perfect drill hole...unless I'm mistaken...and I'm sure I'm not.
As you were gentlemen!


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## GL (Feb 11, 2020)

Got to thinking about this today.  The original question was about making a straight hole.  The adapter doesn't seem long enough to be talking gun drills and  very long diameter to depth ratios or even wild excursion off track.  Threads often make poor mechanisms or features to keep things square to each other.   Is the problem that the hole in the middle isn't straight or that the assembly isn't straight with the bore of the barrel?  The adapter screws to the outside of the barrel, does it seat square of a shoulder or tighten against the last half thread or something similar?  Same with the suppressor, the male thread screws into the tube. The last bit of thread becomes the index point and could pitch the bore alignment.  The other thing I was thinking about was how the part was made - it seems plausible that you turned the part around to do the other end.  Getting things to get exactly (or a reasonable approximation of) concentric and bore aligned on a 3 jaw for this kind of part would be optimistic so assumed you used a 4 jaw.  A gauge pin, range rod, the drill bit you used to make the hole to let you align the bore to the spindle before the outside threads get made may help.  Maybe you already have it covered, but just trying to turn the problem around, maybe the issue is on the outside instead of the inside.


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## strantor (Feb 12, 2020)

GL said:


> Got to thinking about this today.  The original question was about making a straight hole.  The adapter doesn't seem long enough to be talking gun drills and  very long diameter to depth ratios or even wild excursion off track.  Threads often make poor mechanisms or features to keep things square to each other.   Is the problem that the hole in the middle isn't straight or that the assembly isn't straight with the bore of the barrel?  The adapter screws to the outside of the barrel, does it seat square of a shoulder or tighten against the last half thread or something similar?  Same with the suppressor, the male thread screws into the tube. The last bit of thread becomes the index point and could pitch the bore alignment.  The other thing I was thinking about was how the part was made - it seems plausible that you turned the part around to do the other end.  Getting things to get exactly (or a reasonable approximation of) concentric and bore aligned on a 3 jaw for this kind of part would be optimistic so assumed you used a 4 jaw.  A gauge pin, range rod, the drill bit you used to make the hole to let you align the bore to the spindle before the outside threads get made may help.  Maybe you already have it covered, but just trying to turn the problem around, maybe the issue is on the outside instead of the inside.



Ok I see your point. The adapter registers against a shoulder turned on the barrel, and the suppressor registers against a shoulder turned on the adapter. The threads are not used for alignment. Or at least not the primary method of alignment. But the inner threads and outer threads of the adapter do need to be concentric.

I think you may have touched on a flaw in my thought process. See, my original plan was to drill out the blank, thread the barrel-side, thread it onto the barrel, and from then on treat the barrel+ adapter as one piece. Put the barrel back in the lathe with the adapter installed on it, between centers, and machine the OD and threads of the adapter so as to ensure that the suppressor would be concentric to and square with the barrel. That's why it mattered that the hole be straight. 

After so many failures I attacked it a different way. I machined the adapter 100% separately from the barrel. I turned a section of 1" bar stock down to .750", cut it off, and put it in a MT3 draw collet in my headstock. There I drilled it with an end mill almost half way (deep as I could go), turned it around, and drilled it from the other end with the same end mill, almost meeting in the middle, and finished the bore off with my best twist drill. Then proceeded to do my turning and threading. It worked. But since it wasn't my original plan, it felt like a compromise, a last resort that just wasn't "right." I've been obsessing over how to do it "right" ever since. But maybe the first idea isn't the right idea. Maybe I did it "right" in the end, and I should just leave well enough alone. "Right" is whatever works?

But it still bugs the heck out of me that I can't drill a 1/4" hole through 2" of stock without veering off course by an amount painfully obvious to the naked eye.


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## Cadillac (Feb 12, 2020)

Did you try and see where the problem exist on the bad parts? Chuck back up and center, then take a .0001 gauge and see at the end of the hole is centered. Then run the tip of indicator as deep as you can in hole and see if the readings match.


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## strantor (Feb 12, 2020)

I wasn't wrong; there is a gunsmithing subforum. I just didn't look hard enough.








						GUNSMITHING & FIREARMS
					

Show us your gunsmithing & firearm projects and accessories here. Discuss any topics regarding gunsmithing here.




					www.hobby-machinist.com


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## GL (Feb 13, 2020)

My Craftsman lathe drills holes like that.  Test bar showed the spindle centerline ran uphill and away.  Have not fixed it yet.  Fixed problem by getting a new PM1340GT.  Now can mess with old lathe without not having a lathe.  Not an option for some, but it was time to upgrade  anyway.   See threads above for how to check ( graham-xrf and mikey) as a start point.  Remember Rule 1: never let inanimate objects kick you butt.  I share your pain, good luck with the search.


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## graham-xrf (Feb 14, 2020)

strantor said:


> But it still bugs the heck out of me that I can't drill a 1/4" hole through 2" of stock without veering off course by an amount painfully obvious to the naked eye.


Reading Connelly "Machine Tool Reconditioning", (which you can get on this site), I see Sec.14.16 page 105 mentions a cause why a machine will no longer bore a straight hole. Hmm.. the text did say "bore" as opposed to "drill", so I may be wrong about mentioning this.

The lathe may have developed a "wind" where the line of the ways are no longer parallel to each other, this, apparently by the bed having stood for a period not level, or under some stress.

A lathe bed is a big chunk of strong steel, and I would have thought the ways acquiring a "twist" sounds unlikely, but I recall a post on this site mentioning how a lathe bed casting can "take a set" for being out of level, and how it can take time to unbend when again set up level. To check this, you do need a machinist's precision level, and possibly more bits to check it properly. Across the tops of inverted V ways may be OK because they are often a convenient unworn surface.

I don't say this is definitely the cause of the hole going off centre like in your picture, but it is is worth a check if you have not already been there.


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## graham-xrf (Feb 14, 2020)

GL said:


> Fixed problem by getting a new PM1340GT.


 Ohoooooo - YUMMY!



https://www.precisionmatthews.com/shop/pm-1340gt/
OK - I am now nursing some serious symptoms of "other guy's machine" envy.
I dare say @strantor will consider this to be a somewhat OTT fix to his off-centre hole drill problem!


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## GL (Feb 14, 2020)

Thank you, yes, but a man has to do what man has to do...  Off topic, but with similar envy, get the 1440GT with 650lbs more mass.  But turning with the new one is still really cool, especially for a hobby guy used to a Craftsman 12x36 I've had for 30+ years.  The 1340GT is orders of magnitude better


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## strantor (Feb 14, 2020)

I have another lathe. I need to get it running. It's an old 18"x80" lathe, big (ish) boy. It's next in line after I finish my mill refurb. Hopefully it will drill straight holes. If it doesn't, I'm going to look for another hobby.


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## GL (Feb 14, 2020)

At 18x80, I'd say you have arrived at the "I own a chunk of the gravity of the earth" class of lathe.  That's where if you don't own a forklift or a bridge crane or several football players you can't change chucks level.  And 1/2" deep is a good start at a roughing cut.  If you are that far in, and it won't drill straight, sell both, get something new, and smile before bailing.  But I understand the sentiment - you join the club, pay your dues, damn thing ought to do what I told it to do...all I wanted was 2" of straight, not asking for that much out of the deal.


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## graham-xrf (Feb 15, 2020)

GL said:


> At 18x80, I'd say you have arrived at the "I own a chunk of the gravity of the earth" class of lathe.  That's where if you don't own a forklift or a bridge crane or several football players you can't change chucks level.  And 1/2" deep is a good start at a roughing cut.  If you are that far in, and it won't drill straight, sell both, get something new, and smile before bailing.  But I understand the sentiment - you join the club, pay your dues, damn thing ought to do what I told it to do...all I wanted was 2" of straight, not asking for that much out of the deal.


Oops - I fumbled. This reply should have been for @strantor.  Sorry about that!
@strantor :
They can, and do, drill straight, but they have to be treated right. The bigger they are, the more prone they are to gravity. Just think gearbox you need a crane for, and the huge permanent force. The "settling" of the floor. The steady compression creep on whatever wedge you used under it. A big lathe is a great uncompromising thing that will lay it's will into what you cut with a satisfying unyielding firmness, but if allowed to fall into slight misalignment, it will assert that misalignment with the same firmness as when it was straight.

Given the kind of kit you cut metal for, I know much of this about measuring may be second nature to you. It is not so for me. I get upset that I can't make a tenths micrometer read the same measure twice. If not for you, then I put this stuff here for others going up the same learning curve as me.

Beyond leveling, there is the stuff we mentioned in post #22. Do not take fright. Take care with the checkouts, so you don't inadvertently walk yourself into giving up. Measuring this stuff such that errors in the act of measuring do not exceed the alignment error itself is the skill you acquire, mostly by making enough mistakes until you see a consistency that gives confidence.

Please forgive if this is stuff you already know. There are lots of videos on YT. (I almost use YT in place of normal search engine). Keith Rucker's LeBlond lathe example is useful.






Then - there is how to sort out a big lathe in extreme fashion.






If you don't have a 5 arc-seconds level, or a 0.0005" per foot machinist's level (about 9 arc-seconds), you can get there with a plumb bob method. (I was surprised too)!






That last one. He is a Brit from someplace well North of London and Watford. Expect some idiom expressions of a parochial nature - like "gnat's cock"!

P.S. My Dad, in his day, had a building constructions type plumb bob setup all in a 4" plastic drain pipe with a side view port cut-out - to stop air currents.


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## graham-xrf (Feb 15, 2020)

GL said:


> Thank you, yes, but a man has to do what man has to do...  Off topic, but with similar envy, get the 1440GT with 650lbs more mass.  But turning with the new one is still really cool, especially for a hobby guy used to a Craftsman 12x36 I've had for 30+ years.  The 1340GT is orders of magnitude better


Enough already.. Darn it - For PM-1440GT I get to envy what the other guy envies! Is that like envy*envy = envy_squared?
Seriously though, for new kit from Taiwan, and even though the price is out of my ball-park, it looks good value compared to similar quality high precision kit from USA or Europe.


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## John_Dennis (Feb 16, 2020)

Your hole drilling problem could be as simple as a worn misaligned tail stock.  Chuck a piece of bar stock in the lathe without using the tail stock and turn it to the exact dimension of the tailstock ram.  Then extend the tailstock ram and use a straight edge to compare alignment.


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## Cadillac (Feb 16, 2020)

The alignment could be as easy as a bad drill chuck in the TS. A bad jaw in the drill chuck will cock the drill bit. I have one that you can see daylight at the tip of one of the chuck jaws. Needs new jaws. Using a mt testbar In tailstock is your best alignment.


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