Machining metal parts

[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 ;-)