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Discussion Starter #1 (Edited)
I have a small grizzly mill/drill. it has some bells and whistles like DRO in the Y and tilting head.the taper is R8 and the machine itself has been ran hard and put away wet by others. i think the bed is worn. i try to keep it clean, oiled, and the ways adjusted tight-ish, but it obviously is not a quality machine and so somewhat frustrating to use at times. getting a metal lathe is not really in the cards, so I am considering trying to do some light turning with it. I have already done stuff like strange bolts and some random brass pieces by clamping a bastard file or angle grinder in the vice and putting the bolt in a collet or drill chuck. I have been doing this method for years with everythng from cordless drills to my large rockwell drillpress but the mill allows for cleaner cuts and tighter tolerances for this kind of thing. I am not trying to build a spaceship but I am trying to get tolerances in the range of say .005. what I am looking to do right now specifically is machine the inside of a 1.625x.083 4130 tube for a press fit for a sealed bearing. as well as other sizes, mainly for press fits for bearings or other tight tolerance type fits. i would probably try to clamp the cutting tool into the vice in such a way that I could down feed for the cut and control the size of the cut with the X. FWIW I have not used a lathe since highschool metal shop so I don't remember any specifics really. I have been using the hell out of my mill though.

Here's a few questions if anyone wants to take a crack at them.

-what kind of attachments, if any could be used to chuck up pieces of 1-2" OD tubing into my mill?(R8 spindle)

-am i risking damaging the mill in any way with this kind of operation? it probably needs new bearings as it sits. the spindle bearings(i think) are noisy but there is no discernable play if I grab a drill chuck mounted to it.

-what type of cutting tools should i be looking at getting? you can buy just the tool stock and custom grind it correct?

-what are the chances I will be able to get the tolerances I am looking for with this setup?

-how deep of passes could i make with this type of setup?
 

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how long of tube are you talking about counter boring for the seal?

what you are thinking of can be done and has been done quite a bit. i've done a little bit of it on my cnc mill. even on a worn machine, holding a tolerance shouldn't be too hard if you approach the work correctly to get the backlash on the other side of your lead screw (or ball screw). spindle bearings may cause an undesirable surface finish and could make it tough to hold a tolerance.

there are r8 3 and 4 jaw chucks available. if i can find a link to them i'll post it up. you are going to be limited on stickout though. a chuck attachment with a r8 attachment isn't going to be as rigid as a direct spindle mount chuck on a lathe. i don't think i'd push the 2.5 x diameter stickout you typically can with a lathe.

i buy small solid carbide boring bars that have a flat on the top of the mounting area. these could be easily mounted vertically in a mill vise. i'd get the largest one you can and the shortest length of cut that you can get away with. if you mount the tool at the correct angle, you should be able to face the part too.

personally, i'd mount the tool so your cuts are in the x axis so it's easier to see what is going on. i'd find the center in the y axis and lock it down if you can.
 

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in my opinion, you are probably pushing it with a 6" long tube. the chuck is already going to be sticking several inches from the spindle.

edit: most of the stuff i have turned with my mill i had held directly in a r8 collet.
 

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I have done a decent amount of boring large holes on mills ranging from your typical Bridgeport to a 70-ton dual rail head mill.
Always used a boring head to within .001" easily.

With a boring head, you will be able to clamp the tube in the vise and just bore out the end with no problems.

Check out this video. BORING ON THE BRIDGEPORT MILL part 3 Criterion Head tubalcain - YouTube

Edit: Just so you don't think I'm bs'ing you. This is the big mill and a job boring a bearing hole. We did stuff like this all the time. Yes, it is being done horizontally, but the same thing still applies to doing it vertically.

IMAG0004.jpg

IMAG0002.jpg
 

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probably 6" max total length of tube. bearing race depth about 18mm deep into the tube, either side.
You would need to hold that mat'l on the table and use a boring bar or find someone with a lathe.
Dont think there will be enough room on that little mill.

Also you will need to hold the tolerance to less than .005" for any press fits.
 

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I have done a decent amount of boring large holes on mills ranging from your typical Bridgeport to a 70-ton dual rail head mill.
Always used a boring head to within .001" easily.

With a boring head, you will be able to clamp the tube in the vise and just bore out the end with no problems.

Check out this video. BORING ON THE BRIDGEPORT MILL part 3 Criterion Head tubalcain - YouTube

Edit: Just so you don't think I'm bs'ing you. This is the big mill and a job boring a bearing hole. We did stuff like this all the time. Yes, it is being done horizontally, but the same thing still applies to doing it vertically.

View attachment 643018

View attachment 643019


Ahh, the good old boring head. Have done this type of operation on a mill thousands of times. Love using a boring head. You can hold a few tenths if done right, even with a thousands set boring head. I have held .0003/.0004 total tol. many many times with a .001 set head. It's all technique and experience and knowing your tools and tooling and knowing how to get the right surface finish desired or required per drawing. Of course you can turn an OD with a boring head as well. I have done bores as small as 1/8" and as big as probably 8" to 10"

If done wrong though you can sure get into a world of hurt quickly. If using one for the first time make damn sure you have been taught by someone more experienced then yourself. It will save your ass indeed. This type of opperation is not for a beginner machinist to just fool with.
 

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While it can be done, there is a point in time where one must realize that not using the correct tool/machine will not give the best results.

Go buy a lathe. The worst Chi-Com lathe will be easier to set up and conduct the operation than fighting with a milling machine.

Once you get the lathe, you'll be amazed at how often you needed ti and didn't know it.
 

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While it can be done, there is a point in time where one must realize that not using the correct tool/machine will not give the best results.

Go buy a lathe. The worst Chi-Com lathe will be easier to set up and conduct the operation than fighting with a milling machine.

Once you get the lathe, you'll be amazed at how often you needed ti and didn't know it.


Yep, agreed. A lathe AND a mill is good to have. You can do milling on a lathe and turning on a mill but thats not what they're for. A lathe is for making round stuff round, and a mill is for milling & drilling.
 

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While it can be done, there is a point in time where one must realize that not using the correct tool/machine will not give the best results.

Go buy a lathe. The worst Chi-Com lathe will be easier to set up and conduct the operation than fighting with a milling machine.

Once you get the lathe, you'll be amazed at how often you needed ti and didn't know it.
mills can make excellent lathes for small parts and aren't hard to setup at all. i wouldn't try to turn a part larger than the largest milling cutter you would use though. for the size of the op's part, a lathe is definatly the best option with a boring head in the mill being next.
 

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mills can make excellent lathes for small parts and aren't hard to setup at all. i wouldn't try to turn a part larger than the largest milling cutter you would use though. for the size of the op's part, a lathe is definatly the best option with a boring head in the mill being next.
With all due respect, I disagree.

How can you support one end with a tailstock and still move the cutting tool?

Granted, this is a boring process, not really a turning process, and if the piece of tubing isn't too long, there's no reason to not use a boring head.

In this case, there is the issue of having a large enough spindle bore.
 

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With all due respect, I disagree.

How can you support one end with a tailstock and still move the cutting tool?

Granted, this is a boring process, not really a turning process, and if the piece of tubing isn't too long, there's no reason to not use a boring head.

In this case, there is the issue of having a large enough spindle bore.
that's why i said small parts, not larger than the largest tool you would use in the mill's spindle.

this is not my video but i think it shows how well a mill can work as a lathe. if i didn't have a lathe and only had a mill, i'd have no problem turning with it, within reason. the op's part is too big in my opinion but i wouldn't say turning with a mill is a bad idea.

Tormach Vertical Lathe turning and threading - YouTube
 

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i wouldn't say turning with a mill is a bad idea.
I will, that part could have been made faster, less expensively and with a less trained operator on a screw machine, swiss, or manual lathe and quick-change tool post.

How long would it take to set-up that machine to bore the hole through the center of that fitting, compared to if it had been done with a lathe?

Yes, we can make just about anything with any machine if we take the time.

As was said earlier, lathes are for making round parts and mills are for making round parts other than round (paraphrased).

Yeah, I'm usually the one finding an exception to every rule, but this isn't one of them Using a lathe as a mill and a mill as a lathe). And, for the record, I'd love to have a worn-out mill drill, it would beat the Hell out of the file/hacksaw I used for the better part of 40 years and much better than the milling attachment on one of my lathes.

Lathes are such handy pieces of machinery that I'm certain the OP would not be disappointed to have one in his shop.
 

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I will, that part could have been made faster, less expensively and with a less trained operator on a screw machine, swiss, or manual lathe and quick-change tool post.

How long would it take to set-up that machine to bore the hole through the center of that fitting, compared to if it had been done with a lathe?

Yes, we can make just about anything with any machine if we take the time.

As was said earlier, lathes are for making round parts and mills are for making round parts other than round (paraphrased).

Yeah, I'm usually the one finding an exception to every rule, but this isn't one of them Using a lathe as a mill and a mill as a lathe). And, for the record, I'd love to have a worn-out mill drill, it would beat the Hell out of the file/hacksaw I used for the better part of 40 years and much better than the milling attachment on one of my lathes.

Lathes are such handy pieces of machinery that I'm certain the OP would not be disappointed to have one in his shop.
you're crazy if you think that someone could make a pipe threaded part on a manual machine faster than he did on this. that part wouldn't be any quicker to setup on a lathe than it would on this. drilling and boring the hole would be cake in this setup. in fact, it's probably better for chip evacuation while drilling in this method (provided he made provisions to get the coolant up in the part). using gang tooling like he does, the part has the same cycle time as it would on a cnc lathe. the same feeds and speeds are used whether it's being spun vertically or horizontally.

i'm guessing the guy in the video doesn't have a cnc lathe and probably doesn't need one bad enough to justify the cost and real estate it would take up. i can guarantee that those parts couldn't be made cheaper if you had to go out and spend $30k+ on a new lathe. probably along the same reasons the op doesn't already have a lathe.

i am sure you know that a vertical mill is just a lathe turned on it's side. even the axis stay the same. you aren't going to hurt it if you keep the part size reasonable.
 

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you're crazy if you think that someone could make a pipe threaded part on a manual machine faster than he did on this. that part wouldn't be any quicker to setup on a lathe than it would on this. drilling and boring the hole would be cake in this setup. in fact, it's probably better for chip evacuation while drilling in this method (provided he made provisions to get the coolant up in the part). using gang tooling like he does, the part has the same cycle time as it would on a cnc lathe. the same feeds and speeds are used whether it's being spun vertically or horizontally.

i'm guessing the guy in the video doesn't have a cnc lathe and probably doesn't need one bad enough to justify the cost and real estate it would take up. i can guarantee that those parts couldn't be made cheaper if you had to go out and spend $30k+ on a new lathe. probably along the same reasons the op doesn't already have a lathe.

i am sure you know that a vertical mill is just a lathe turned on it's side. even the axis stay the same. you aren't going to hurt it if you keep the part size reasonable.


Agreed.
 

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OK, I watched the video through to the end. They didn't do the through-drilling-that I think would require the longest set-up, getting a drill aligned with the center line of the fitting.

A nice heavy lathe should be able to do that nearly as quickly, and could certainly do the through drilling with much simpler set-up.

And, a mill is not a lathe on its side, by definition, a lathe turns the workpiece while tools are introduced to the workpiece, in milling, the tool moves and the workpiece remains stationary-yeah, there are exceptions, but it's the rule, not the exception.

I don't have a real mill, I can't see not having a lathe though as there are so many things I can do with the lathes that I don't think I could do as well with a mill.
 

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OK, I watched the video through to the end. They didn't do the through-drilling-that I think would require the longest set-up, getting a drill aligned with the center line of the fitting.

A nice heavy lathe should be able to do that nearly as quickly, and could certainly do the through drilling with much simpler set-up.

And, a mill is not a lathe on its side, by definition, a lathe turns the workpiece while tools are introduced to the workpiece, in milling, the tool moves and the workpiece remains stationary-yeah, there are exceptions, but it's the rule, not the exception.

I don't have a real mill, I can't see not having a lathe though as there are so many things I can do with the lathes that I don't think I could do as well with a mill.
finding the center of the drill isn't any harder than finding the center of a round part mounted in a vise. granted, we're straying from the op's question here, but with a gang tooling setup on a cnc like in the video, you find the tool center one time and store the offset in the control. the machine always knows where that tool is. you need to locate the tool in a cnc mill the same way.


so, have you ever done any simple milling with your lathe because you don't have a mill?
 

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Discussion Starter #20 (Edited)
very interesting stuff. I did look into some lathes but the ones I could begin to afford right now dont quite have the capacity I would want. I am fairly set on spending about 1500 on a good used real lathe when I do. for this project I am getting a cheap boring bar set and a adjustable reamer set. thanks very much to everyone who replied.
 
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