110v single phase bridgeport motor swap

[stanglou]

I have a line on a really cheap used bridgeport mill. The problem is that i can only run 110V single phase tools. has anyone ever swapped a bridgeport motor out for a single phase motor? What would be the pros and cons of it? Also, where would i get that type of motor? Suggestions on brands and sites to purchase it from?

[NC Cams]

Buy the mill and don't mess with the motor..

You can buy phase converters to go from 110/220 single to 3 phase from many places. "Home Shop Machinist" magazine has all kinds of adds for them.

Perhaps someone can provide a link to a site where you take a surplus 3 phase motor, a capacitor or two and self generate 3 phase. I've seen it described but a schematic would be VERY helpful to the neophyte - especially how to "start" the 3 phase motor on single phase.

[mxtras]

Just use a VFD. Google or search this site.

Scott

[Al_The_Man]

I agree with scott, if it has a three phase motor, you can usually pick up a VFD on ebay and you get the advantage of programmable spindle speed.
Al.

[vacpress]

these VFDs on ebay confuse me. 95% seem to be 220V or higher.

I have this issue also.. 110v 1-phase.. cannot goto 3phase without great difficulty and cost...

ive seen some interesting things on ebay, in the rotary-converter department... but these are usually at least $1,100.. More than my 3-phase tool is likely to be worth...

can someone maybe do a quick scouting and show us which of the non-rotary VFDs would work?

i am really considering swapping the motor for a 1-phase. I REALLY want my nice big table saw with it's bad-ass fence and extension table! I have been using it as a drill-press stand since I moved!

Thanks!

[Al_The_Man]

Most 3phase VFD's start at 220v because most 3phase motors start at this voltage range, almost every household in N. America has 240v 1ph so voltage is not usually an issue.
I would not even look at any inverter that is 1ph in 1ph out, as 1 phase motors do not take to variable frequency that well.
3 phase motors are superior to 1ph so I would not change unless you have to.
The High speed 3 phase spindles (~10,000rpm & up) are expensive due to the quality construction, bearings etc required, these also require a high frequency VFD.
The cheap way of achieving High speed spindle is 120v Universal motor.
Al.

[vacpress]

hey al,

what about this:
http://cgi.ebay.com/Saftronics-VSM-m...QQcmdZViewItem

it looks jsut like the VFD i have used in a medium sized commercial router... but the inputer voltage is still 220\240 3phase? this means it cannot run a 120v 1-phase motor, yeah?

thanks..

[Al_The_Man]

It cannot run a 1 phase motor, period.
The problem with 1ph VFD is that the motor usually has to be capacitor start/capacitor run, i.e. no centrifugal starting switch. Also they tend to drop out of run if taken too low on load.
I am talking squirrel-cage induction motor, not the brush Universal type.
Al.

[mxtras]

I have a quick question for those of you that say that you only have 110: you realize that you do have 220 to your house, right? It may not be in your shop, but it's in your house. Why can you not run a sub-fed panel to your shop and end your handicap? It's not really all that difficult. Is it because of too much expense, too much trouble or not enough need?

Just thought I'd ask. I cannot image shop life without 220.

Scott

[Al_The_Man]

its too bad that this part of the world went with the 120/240 centre tapped idea for distribution, In many parts of the world, 3ph & neutral is distributed to residential areas with each group of homes fed from a single phase ~240 and neutral, it was relatively easy to get three phase in, at the time I lived there, the power company insisted on putting in three phases and neutral when I wanted a large electrical heating load.
Al.

[vacpress]

Well. I dont live in a house, I live in a strange industrial building's once-used offices... Loft-like place..

Anyways, generally all the tools I have seem to be either 120v 1-phase, or it is my single 3-phase tool, a big table saw. I was told years ago that to get 240V from any house-wiring, you take '1 wire' from each of 2 different circuits, and the 2 are then 240V, i could be forgetting that you have to tie the other 2 wires together, but i am not certain, and would be extremely afraid to try...

what good would 240v 1-phase do for someone who need 3-phase?


Thanks.. I know this gets discussed all the time, but sometimes searching threads is counter intuitive!

[NC Cams]

Vacpress: cut your current draw in half which usually results in less voltage drop and resultant even higher current when equipment starts.

Thus, if you have 1 phase 110 and draw 20 amps, you'll only draw 10 amps if you rewire the motors capable of doing so to run 1 phase 220. If you could go to 440, current would drop to 5 amps.

All commercial and residential buildings that pass code inspections for single phase that I've seen been in lately with my business interests were wired for 110/220.

In these cases, they bring in 220 (110 on each leg of transformer) and half the circuits are run off of 1 leg and the other half off the other leg. This ballances loading of transformer

If you install a 220 breaker into a properly wired 110/220 service panel, it automatically connects to the 2 legs and, wah lah, 220.

BTW, my old house was built in the ealy 1900's and wired with knob and tube. Yet the breaker panel was 110/220 (redone sometime in the 50's). I'd be really surpised if your loft, unless it has really butchered wiring, is any different.