Polish hole drilling (using a mill as a gang lathe).

Nathan the Machinist

Nathan the Machinist

KnifeMaker / Machinist / Evil Genius
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This is a rather unusual technique to drill holes in the mill, work piece is in the spindle and the bit is held in the vice. My "Polock" drill rig:

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I'm turning the shouldered pins for attaching scales to the handle in a mill

First thing I do is center drill, to prevent the bit from walking

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Then I drill my hole

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The I finish turning the pin and part it off (there is a lathe tool insert held in the vice).

34.jpg


This makes these shouldered scale pins. I'm aware the finish is lousy. Believe it or not, this technique can create a finish that almost looks honed, but in this case I *want* a rough finish for the epoxy to sit in.

35.jpg
 
excellent. So the male/female parts of the pin halves are just pressed and epoxied together? No threads? How are the drill chucks fixed in the vise?

Nathan - I just came across your thread where you mill the bevels - THANK YOU - it was great. I was thinking that you would mill the blade with the blank in the X-Y plane (i.e. flat on the table). Now I see that you can mill the blank while it's clamped in mid-air because only a small corner of the cutter is contacting the workpiece. Amazing.
 
patriqq said:
excellent. So the male/female parts of the pin halves are just pressed and epoxied together? No threads? How are the drill chucks fixed in the vise?

Nathan - I just came across your thread where you mill the bevels - THANK YOU - it was great. I was thinking that you would mill the blade with the blank in the X-Y plane (i.e. flat on the table). Now I see that you can mill the blank while it's clamped in mid-air because only a small corner of the cutter is contacting the workpiece. Amazing.
Click to expand...


The drill chucks are mounted on straight shanks. Those straight shanks fit 5/8" holes bored in the vice jaws. You can get the picture by looking at the vice jaws on the larger vice, the holes are present, though there is nothing in them.


The rough areas of the pins are a bit of a press fit between the scales, tang and the other side of the pin. I epoxy everything up and squeeze the pins together with a pair of pliers, though not so hard that I squeeze all the epoxy out of the joints. The one pin is pressed into the other 1/8". With the small barbs and the epoxy that is a strong joint. I then put a spring clamp on each pin and set the knife aside to cure, which takes 24 hours.
 
slick. When you bore the vise jaws, do you have a spacer in-between them, so when you tighten the vise, the jaws bottom out on the chuck shank, as opposed to bottoming-out on eachother?
 
patriqq said:
slick. When you bore the vise jaws, do you have a spacer in-between them, so when you tighten the vise, the jaws bottom out on the chuck shank, as opposed to bottoming-out on eachother?
Click to expand...

That is the general idea. These were done a little differently. Everything was machined from the face surface so the mounting holes could be done in the same setup, but the clearance you're referring to is there.

Often, when making a fixture to hold a round part, you make it a triangular clamping setup so you have three distinct contact lines, prevents the vice from closing up and contacting the part in just two lines, allowing it to rock. (This is a difficult concept to explain). But these were done this way because they were originally being used to hold copper (fuel injector gasket prototypes for Siemens I believe) and I could not hold the parts with flats without risk of deforming the soft copper, so round it was.
 
A: It is useful to show folks that you can turn in a mill. Turning something in a lathe wouldn't really be "start a thread" worthy. Lots of folks here have a mill, but no lathe, and may not have considered they could turn a part in it.

B: A CNC mill is better than a manual lathe when you have 40 parts to turn (which I did). Lots of folks are in that boat.

C: I have a CNC gang lathe. But in this case, for me, it was simpler to use the mill this time.


D: it gave me the opportunity to use the epithet "Polock" on a public forum.
 
I did my rings that way before I got my CNC lathe. Seems to work fine, although it's not as stiff as using the lathe and chucking right at the end of the bar.
 
Thanks for another great thread, Nathan! I envy your machines, If I could I would probably spend all day at the milling machine or one of the lathes at school.

Quick, dumb question about cnc mills: how does the machine know how deep it has cut?
 
Keith a CNC machine has measuring devices on all the axis of travel so it knows how far it has moved in any direction. You have to zero each tool so the machine knows that.
 
Thank you Jim. Sorry to be slow Keith.

Just as Jim said. The machine doesn't know how deep it is in a cut. Pretty much all it knows is where it is on its axis travels. The machine goes where you program it to at whatever feed rate you instruct. If there is a cutter, and material to be cut, you get chips. If there is a vice or the table, you get a crash. The mill doesn't care much regardless.

On a part like this with different tools you can measure the location of the tools (with a coaxial indicator on dowel pins for the chucks, with a touch probe on the lathe tool) and enter their locations relative to machine zero in an offset table in the controller. Then you can call those offsets during the program so all your cutting takes place at 0,0,0 in the programs even though the tools are at different physical locations. But the long and short of it is, it goes where you tell it.
 
Thanks Nathan. It is an excellent solution I surely will try it tomorrow or so. :thumbup:
 
ib2v4u said:
Keith a CNC machine has measuring devices on all the axis of travel so it knows how far it has moved in any direction. You have to zero each tool so the machine knows that.
Click to expand...

Nathan the Machinist said:
Thank you Jim. Sorry to be slow Keith.

Just as Jim said. The machine doesn't know how deep it is in a cut. Pretty much all it knows is where it is on its axis travels. The machine goes where you program it to at whatever feed rate you instruct. If there is a cutter, and material to be cut, you get chips. If there is a vice or the table, you get a crash. The mill doesn't care much regardless.

On a part like this with different tools you can measure the location of the tools (with a coaxial indicator on dowel pins for the chucks, with a touch probe on the lathe tool) and enter their locations relative to machine zero in an offset table in the controller. Then you can call those offsets during the program so all your cutting takes place at 0,0,0 in the programs even though the tools are at different physical locations. But the long and short of it is, it goes where you tell it.
Click to expand...

Thanks guys, I use the old milling machine at school a lot, I wish we had proper fixtures, cutters and measurement tools (closest thing is the vernier callipers I brought from home- which is a bother since I am a perfectionist). So it is a little odd to see a machine start at the centre of it's travel and goes over and makes a perfect cut with any length cutter.

It is neat to see all the things you can do in a milling machine, the people in my class use it just as a rough surfacer for their bubbly aluminum castings, which I find sad.
 
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Kieth, Hey I am a real hack with one. I know very little. My cousin is a CNC guy who made body replacement parts for a long time. IE knees, hips, bone screws etc. He now makes stuff for the high tech industries. I have seen him work and some of his pieces. It is flat amazing what you can do with a mill. You keep at it and learn as much as you can and then go to a good trade school. I think that there will always be a place for skilled machinist and metal workers. Don't become a machine operator, Become a real machinist. CNC is the best but, learn how to actually make things not just run the machines. If you can make say a progressive threaded taper or a replacement worm gear you will be valuable. If you can only set up a machine to run someone elses programs etc you will not be. Be a responsible, thinking, productive worker and you will always have good work and be able to pick your jobs after the word gets out about you. Jim
 
Thanks, Jim. I don't mean to hijack this thread.
Even though I like machining, I am not sure if that is what I want to do as a career for a few reasons. Is there any money in machining? It seems like it would be hard to find a high paying job in a shop, and risky to eventually open your own.
Also, is there a level of creativity in working in a machine shop and can it get repetitive? Thanks.
 
Where I work the machinist make a bit over $30 an hour and have excellent benefits. Some of the stuff they do is boring I am sure. Some of it must be interesting. Most of them are far beyond machine operators. Innovators and problem solvers often hand in hand with the engineers. Same with the shop I work in. (metal skills) But, no matter, remember, the hard thing for an employer to find is a thinking, responsible person, who wants to get the job done safely, correctly, efficiently and timely. They all go hand in hand. Enjoy your metal shop and remember this things and no matter what you decide to do. Be skilled. Jim

PS, You know you are just above me so If you ever come down to the states on I5 call me ahead of time and stop by
 
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