Machining metal parts

[3Ts]

In the Drill Press Cross-Feed Table there were some posts where I learned some things to look for in tools. I'm interested in doing some machining as in making some of my own parts, especially if I can't find a replacement, but have never done any machining. There is one machinist in town that I can ask questions of, but he has a business to run and I don't want to interfere with his paying job. So since y'all have been helping one another on this forum I'm going to ask some questions about machining. Keep in mind that my knowledge of this is that I can stick 2 pieces of metal together with a welder and drill holes with a drill press. I also know that there are different alloys of steel, some are not machinable, some can be hardened after machining. Beyond that - not much. So:

Let me start by asking what I should look for in a mill. Ummm, no. First question is what is a mill used for? I think it can be used for cutting slots and keyways, trimming edges once a piece is cut to approximate size, and with a ??? (a circle thingy with a crank) can make circular parts. I believe it would be the first tool in a machine shop and that it should have an R8 chuck. I realize this is a wide open question and I really don't know where to start so comments and guidance is appreciated.

 

[LouNY]

I'm not a machinist by any stretch of the imagination,
I do have my Bridgeport mill it is a small low power one it has a 1 hp 120 volt single phase motor on it.
I have a few milling cutters for it and have managed to make a few pieces and clean up some parts to be reused.
Surfaced a couple of exhaust manifolds so they would seal better, just minor things.
My most common use is as a drill it works so much nicer then any drill press I have ever had.
Plus I picked this up for $500 with several collets and bits and a drill chuck.
Then I have a small very old lathe, it is a South Bend C9-10JR I picked this up for $100 a few decades ago,
I turn a few shafts down and made bushings to weld on them to bring them back to size, made a few little pieces and parts.
Some bronze bushing to fit backhoe pins and tighten up the slop in worn pins and holes.
Even made a puller for pulling engine sleeves on a Allis Chalmers WD45.
The last few years U-tube has been a helper on doing things before that I used old manuals and military training guides.

 

[ultrarunner]

Have a small shop set up with Southbend 10" Lathe and Bridgeport NC Mill, rotary table, 12" disk sander, Belt Sander, a couple of welders, etc

All used in restoring cars and for a time a small side business fabricating Monel and 316 shafts for antiques.

Mill is great... Lathe could be larger...

Sadly not much use the last 20 years but handy none the less.

When I bought in the 80's prices were high but as manufacturing left the SF Bay Area machine tools plentiful and even cheap... sometimes scrap cheap.

One thing is many are three phase which means a convertor or swapping motors.

Lots of three phase is heavy duty but many home shops pass.

 

[Root Cause]

For starters, a mill is often used to make bar stock into mostly square shapes.

The real beauty of a good milling machine is that you can make accurate square or (whatever) blocks and then accurately drill holes and ream them to very accurate sizes. Holes can be accurately spaced apart, from an edge, or from the center of your work. This enables one to take multiple parts, bolt or dowel them together to make a machine or ????

You are correct, with other equipment, you can make round parts or various hole patterns.

I loved running a lathe (mostly to make round parts). it is the only machine that can duplicate itself. It's history goes back to the British Navy needing bolts and nuts. It's off topic but imagine those craftsmen who sat at a vise every day making bolts and matching nuts with a file for their entire lives.

R8 might be the most common but other sizes work just as well. Once you have that determined, then you want to buy collets, drill chucks and other items that will fit. For that reason, R8 is a good choice because it is easy to find accessories for it. Good luck.

 

[Jims1025R]

I had a nice 20 book encyclopedia set of books all about machining, they would answer your questions! I am a machinist. If you could make your questions a bit more specific, they'd be easier to answer. But, we're here to help in any case...

A milling machine will turn a cutter (expensive to break off) which will cut a flat surface or slot, or locate a number of holes with fair precision. Endlessly useful tool, though you can spend as much on accessories (a vice, rotary table, clamp kit, dividing head, boring head, collets, mills, etc.) as the mill costs. and you'll need some measuring tools to know where you're cutting.

A lather turns things so you can make them round, or drill concentric holes down the middle. Also very useful for cutting male threads, but skill required for that.

Yes, there is all kinds of steel. The most handy thing to save you wrecking an expensive end mill, is a cheap file. If you can't file it, you can't mill it.

Chucks hold drills, usually 1" diameter and smaller. Larger drills have a morse taper shank (there are exceptions, but this is common). Collets hold end mills, and certain size drills. Collets are much more precise, and long term precise than chucks.

I hope that's a small start for you. Youtube is your friend....

 

[LD1]

I have a Monarch 16x54 lathe and a Bridgeport 2hp knee mill that was formerly a CNC mill (nice ball screws on everything).

Pretty much good advise so far on what a mill can do. Not much to add.

If you are considering shopping/purchasing one.....you need more knowledge/education than can be done on an internet forum. I'd go to the machine shop you have in town....even offer to pay a few $$$ but shadow whoever is running the mill for the day and ask questions. There are lots of Do's and Donts that pertain to safety. And hands on and seeing someone do those things in person....and explain to you why would do way better than me telling you on a forum.

 

[MickeyDBC]

Welcome to the very heavy hobby of machining where one day your wife will look at all of the crap you have accumulated and hopes that she dies first and does not have to deal with it. I got back into it about 20 years ago and now make a living with it after abandoning the IT industry for another one with almost as much tech but weighs much more.

Youtube is your friend, search for something you want to do and there are probably 50 videos of instructions. Subscribe to their channels and you will constantly be presented with new videos. Join the Home Shop Machinist web forum and subscribe to their magazine. Resist the urge to buy chinese equipment - most of it is junk with very hard to replace parts. Have a good pickup that you are not afraid to abuse. Keep some cash rat holed at home because screaming good deals always come along when the banks are closed for a three day weekend. And always remember to have fun.

 

[jwmorris]

Depends what you want to do, if you want to have an awful finish, tiny cuts and greatly increase your chance of breaking your drill press you could use one as a mill.

A mill has many uses but might as well be a rock if you don’t have tooling and some are not much more than a drill press with a stronger method of holding the tooling that a taper mounted Chuck.

Personally I would be on the lookout for a used but not beat up Bridgeport series 1 or clone. Buying used equipment often comes with extras that can turn out to be more valuable than just a machine.

As you noted a rotary table or index can add versatility but the last one I bought also came with things like DRO, rotary 3 ph converter, power feed, collets, end mills, drills, 5c collet fixtures and collets, that if bought on their own, would have cost more than just the mill.

That said, often a lathe is the most useful of the two. What kinds of things are you trying to make?

 

[Root Cause]

Depends what you want to do, if you want to have an awful finish, tiny cuts and greatly increase your chance of breaking your drill press you could use one as a mill.

A mill has many uses but might as well be a rock if you don’t have tooling and some are not much more than a drill press with a stronger method of holding the tooling that a taper mounted Chuck.

Personally I would be on the lookout for a used but not beat up Bridgeport series 1 or clone. Buying used equipment often comes with extras that can turn out to be more valuable than just a machine.

As you noted a rotary table or index can add versatility but the last one I bought also came with things like DRO, rotary 3 ph converter, power feed, collets, end mills, drills, 5c collet fixtures and collets, that if bought on their own, would have cost more than just the mill.

That said, often a lathe is the most useful of the two. What kinds of things are you trying to make?

Well said.
Like most hobbies, the machine, tractor, or ATV is just a downpayment on all the stuff that you buy after you thought you had something.

 

[s219]

I worked in a machine/model shop part time during my college years -- started cleaning machines at the end of the day and gradually moved up to basic machining tasks on a Bridgeport and lathe. Got lucky that one of the model makers saw something in me and took me under his wing. By the end I could make almost anything and it was a wonderful feeling.

So many times over the years I wished I had my own machines because they give you a high level of independence and capability to fabricate and repair stuff. I still use machines at work occasionally when we get into a pinch, but have never been able to find the space/need to have my own machines at home. I figure it will be a good retirement project someday.

I'd say if you have any inclination, go for it. It's a great way to start as a hobby that turns into a valuable life skill.

One of the coolest things I remember was all the different materials we worked with. I'd say most of the work I did was with aluminum, which cuts very nicely. But in a model shop we worked with everything, including plastics and composites. I machined some real nice parts out of urethane and delrin. Delrin is a great material for all sorts of uses and machines beautifully on a Bridgeport and lathe.

Definitely be prepared for the cost of materials and tooling. Whenever I have looked at used machinery, I tend to focus on the machinery cost, but procuring material and keeping up with tooling, cutters, and supplies can be very expensive. You'll also need maintenance supplies, lubricants, way oil, etc.

 

[jthibodeau89]

Deals are out there. Watch forums, marketplace, auctions. I picked up a 3hp ACRA 10x54 knee mill for $1375. After selling my Enco round column to a buddy and upgrading to a 6" import vice, my net cost was $500. Beware most industrial equipment is 460 3ph. The 3ph requires either a phase converter or a VFD. The bigger issue is the 460v. Most motors can be reconfigured from 460 to 230, but a 380-480v VFD will not run on 230v. I also had to get a 230v VFD for the mill until i come up with the 230-460v step up xformer. I already have a 230v 7.5hp RPC.

 

[LD1]

I still use machines at work occasionally when we get into a pinch, but have never been able to find the space/need to have my own machines at home.

Sounds like someone is overdue for building themselves a big ole shop

 

[LD1]

Deals are out there. Watch forums, marketplace, auctions. I picked up a 3hp ACRA 10x54 knee mill for $1375. After selling my Enco round column to a buddy and upgrading to a 6" import vice, my net cost was $500. Beware most industrial equipment is 460 3ph. The 3ph requires either a phase converter or a VFD. The bigger issue is the 460v. Most motors can be reconfigured from 460 to 230, but a 380-480v VFD will not run on 230v. I also had to get a 230v VFD for the mill until i come up with the 230-460v step up xformer. I already have a 230v 7.5hp RPC.

Yep, you get something 460-480 only you are kinda screwed. You can always use a step up xfmr but for the cost you might as well get a new motor.

ALWAYS check the nameplate and make sure it can run on low voltage 3ph.

IF no nameplate pop the cover and hope to see 9 wires coming out of the motor and not 3

 

[MickeyDBC]

Yep, you get something 460-480 only you are kinda screwed. You can always use a step up xfmr but for the cost you might as well get a new motor.

ALWAYS check the nameplate and make sure it can run on low voltage 3ph.

IF no nameplate pop the cover and hope to see 9 wires coming out of the motor and not 3

480 volts is your friend because people are scared of it. Watch out for a decent used transformer that will run up to 10HP and it will let your run a lot of equipment that is heavily discounted because it is 480. Here is a good rule of thumb on three phase motors - if it is dual speed (say 1725/3450 rpm as an example) you cannot change the voltage on it. A lot of single speed machines can have the motor taps changed to change the voltage.

 

[ultrarunner]

Don't overlook community college or vocational school classes.

There were.guys that signed up for shop time to work on their own projects...

No idea in the era of Covid because it is hands on...

 

[big bubba]

agree w/above
you'll get a lot of good info in this forum as well.... highly recommend taking something like an adult ed evening class, etc. to get a start on basic machining. i wouldn't start sinking money into machines you're not sure about. you'll get lots of ideas on this thread, but personally i'd get some hands on 1st. usually high school & post secondary vocational programs have adult night classes for the public. let us know how you do....

 

[jthibodeau89]

Yep, you get something 460-480 only you are kinda screwed. You can always use a step up xfmr but for the cost you might as well get a new motor.

ALWAYS check the nameplate and make sure it can run on low voltage 3ph.

IF no nameplate pop the cover and hope to see 9 wires coming out of the motor and not 3

Motor is fine, 230/460. But the variable speed is via OEM VFD. VFD is 380-480 3ph input. No worries, as i plan to get a 20~15kVA step-up xformer. That way i can have both 230v 3ph and 460v 3ph from my 230v RPC.

 

[etpm]

In the Drill Press Cross-Feed Table there were some posts where I learned some things to look for in tools. I'm interested in doing some machining as in making some of my own parts, especially if I can't find a replacement, but have never done any machining. There is one machinist in town that I can ask questions of, but he has a business to run and I don't want to interfere with his paying job. So since y'all have been helping one another on this forum I'm going to ask some questions about machining. Keep in mind that my knowledge of this is that I can stick 2 pieces of metal together with a welder and drill holes with a drill press. I also know that there are different alloys of steel, some are not machinable, some can be hardened after machining. Beyond that - not much. So:

Let me start by asking what I should look for in a mill. Ummm, no. First question is what is a mill used for? I think it can be used for cutting slots and keyways, trimming edges once a piece is cut to approximate size, and with a ??? (a circle thingy with a crank) can make circular parts. I believe it would be the first tool in a machine shop and that it should have an R8 chuck. I realize this is a wide open question and I really don't know where to start so comments and guidance is appreciated.

Yeah, get a mill. If you have the space get a Bridgeport or a copy. You will appreciate the weight. And the versatility. Especially the versatility. Yes, it should have the R8 taper. In the USA R8 taper tooling is the most common by far. Offer to pay the machinist you know to look at any machine you want to buy. Bridgeport type milling machines are very versatile. The head can be tilted in two planes. The head is bolted to the ram. The ram slides in and out of the saddle. The saddle sits on and is bolted to the column. The saddle can be loosened and then rotated on the column. It can be rotated 360 degrees. Most folks never use all the features the mill has to offer, but they are there and you never know when you will need to use your machine for that really weird job. Mills are used for squaring parts up, machining them to length, cutting slots, drilling holes, tapping holes, broaching keyways, etc. With various attachments you can cut gears (dividing head), make round parts, or sections of a round part (rotary table), drill holes in the ends of very long parts (right angle head), and the list goes on.
Eric

 

[etpm]

I forgot to add that a variable speed head is by far the best. With larger tools, like big drill bits, the spindle speed needs to be llowered. A step pulley head just gives 8 speeds, 4 low and 4 high. You can use a VFD to lower the speed electronically but the torque stays the same as the speed is lowered. This means the power output drops. Larger diameter tools need higher torque, they need all the power the machine can put out. You can compromise with a step pulley head and a VFD, but it is a compromise. Most likely you will be looking at machines with 3 phase motors. Most likely you have single phase power only. No biggie. Just buy or make a phase converter. You can buy VFD that will make 3 phase from single phase but I wouldn't unless you need to vary the motor speed. Instead buy or make a phase converter. They are easy to make, there are plans all over the internet. They can be very simple, just a 3 phase motor that you spin up with a rope. I did this just for fun, but don't recommend it. You can also start a 3 phase motor spinning with a single phase motor and then disconnect the motors from each other once the 3 phase motor is spinning. Kind of a hassle but I have done it. The guy I did it for is still using the set up and it's been over 25 years since I made the set up. Even though all you need to make 3 phase is a 3 phase motor the power coming out will be unbalanced which leads to less than optimal performance of any motors powered by the phase converter. This can be fixed with capacitors. The reason a 3 phase induction motor can supply 3 phase power is because induction motors operate as a generator too. So when the motor is running it is not only consuming power it is also generating power. If a 3 phase motor is connected to single phase power it will just vibrate and overheat. But if the motor is first spun up and then single phase power is supplied it will continue to spin. And will generate power. In all three wires coming for the motor. You only care about the one wire not connected to the single phase though because you will be using that wire as one of the 3 needed for your 3 phase power. If you want to learn more about this all works, induction motors, you will need to look on your own. The subject is complex. I started over 40 years ago by reading books and was able to make my first phase converter without instructions, but now so many good folks have posted instructions online on how to make self starting and well balanced phase converters that you don't need to know anything about electricity to make a very good phase converter. Well, that's it for now. I went on too long, I hate typing on my tablet, and I want relax.

 

[CalG]

There is this,

https://bbs.homeshopmachinist.net/forums/3-General

fun bunch of eccentrics ;-)